The Harwell Science and Innovation Campus, site of cutting-edge research into batteries
The hunt is on for the next generation of batteries that will power our electric vehicles and help our transition to a renewables-led future. In this talk, Serena Corr looked at the science behind batteries, discussing why we are hunting for new batteries and investigating what tools we use to pave this pathway to discovery. Serena showed how researchers at the Faraday Institution are developing new chemistries and manufacturing processes to deliver safer, cheaper, and longer-lasting batteries and provide higher power or energy densities for electric vehicles.
The Faraday Institution was founded in October 2017 as the UK’s independent institution for electrochemical energy storage science and technology supporting research, training and analysis.
Serena Corr obtained her BA (2002) and PhD (2007) in Chemistry from Trinity College Dublin. She completed her PhD work on New Magnetic Nanostructured Materials with Professor Yurii Gun’ko, where she developed new magnetic materials for biomedical applications. In 2007, she began working as a postdoctoral researcher in the Materials Research Laboratory with Professor Ram Seshadri at the University of California, Santa Barbara where she studied metal-insulator transitions in vanadates. After a lectureship at the University of Kent, Serena joined the School of Chemistry at the University of Glasgow as a lecturer in Physical Chemistry in 2013, was promoted to Reader in 2016 and made Professor and Chair of Energy Materials in 2018. In October 2018, she joined the University of Sheffield as Professor and Chair in Functional Nanomaterials, as a joint appointment between the Departments of Chemical and Biological Engineering and Materials Science and Engineering. Her research focuses on the design, synthesis and characterization of functional nanomaterials in particular for applications in energy storage, with an emphasis on understanding their intimate structure-property interplay. She is associate editor of the RSC journals Nanoscale and Nanoscale Advances, IOP journal Progress in Energy and sits on the editorial boards of Chemistry of Materials and Nanoscale Horizons.
She was Theme Coordinator for Energy Conversion and Storage for the Scottish Energy Technology Partnership until 2018 and is a member of the Supergen Energy Storage Hub and Science board. Serena also serves on the scientific and organising committees for a number of conferences (including the UK Energy Storage conference 2016; ISACS: Challenges in Inorganic Chemistry 2017; 16th European Solid-State meeting 2017). Serena was appointed to the EPSRC Strategic Advisory Committee in 2017, a post she will hold for three years. She has published over 50 refereed publications, including five invited book chapters. She was awarded the 2017 Royal Society of Chemistry’s Journal of Materials Chemistry Lectureship.
The following are notes from the on-line lecture. Even though I could stop the video and go back over things there are likely to be mistakes because I haven’t heard things correctly or not understood them. I hope Professor Corr, her colleagues and my readers will forgive any mistakes and let me know what I got wrong.
Lithium ion batteries have revolutionised the portable media industry.
Batteries are also being increasingly used in electric vehicles and large-scale energy storage,
Research into energy storage is vital if we want a reliable source of sustainable electric power.
The demand for lithium ion batteries is so strong that the cost of production is expected to exceed 73 billion dollars by 2025.
Research into batteries is important because the use of petrol and diesel should be phased out by 2035.
The search is on for even better batteries than the ones we have now.
A little quiz
1) How many AA batteries would it take to charge a mobile phone for a year?
Is it 8, 80 or 800?
The answer is 800
2) Which are there more of?
Is it dogs in the world, batteries thrown away each year or cars on the road in the UK?
The answer is batteries thrown away in a year. 3 billion are thrown away.
3) How many emperor penguins are equivalent to the typiccal mass of a car battery?
Is it 1, 5 or 10?
The answer is 10. A typical emperor penguin has a mass of 23kg
4) In which century was the electric car invented?
Was it the 1800s, 1900s or 2000s?
The answer is, surprisingly, the 1800s
Electric vehicles circa 1900
One of the many Fritchle electric cars manufactured in the early 20th century. 30003403, History Colorado
Oliver Parker Fritchle (September 15, 1874 – August 1951) was an American chemist, storage battery innovator, and entrepreneur with electric vehicle and wind power generation businesses during the early twentieth century.
The first mass-produced electric vehicles appeared in America in the early 1900s. In 1902, “Studebaker Automobile Company” entered the automotive business with electric vehicles, though it also entered the gasoline vehicles market in 1904. Around this time a third of all cars were electric. However, with the advent of cheap assembly line cars by Ford, electric cars fell to the wayside and due to the limitations of storage batteries at that time, electric cars popularity faded away.
Edison and a 1914 Detroit Electric model 47 (courtesy of the National Museum of American History)
Thomas Alva Edison (February 11, 1847 – October 18, 1931) was an American inventor and businessman who has been described as America’s greatest inventor.
Edison said “Electricity is the thing. There is no whirling and grinding of gears, there is no dangerous and evil smelling gasoline and there is no noise”.
In 1901 President McKinley was rushed to hospital in an electric ambulance after he was shot whilst visiting Buffalo, New York.
William McKinley (January 29, 1843 – September 14, 1901) was the 25th president of the United States from 1897, until his assassination in 1901.
In the 1800s you could travel 30 miles per charge but modern electric vehicles can do about 250 miles per hour, although this value is affected by how and where the car is driven,
Research into batteries is trying to improve this range despite the fact that the average car journey in 2018 was only 6.6 miles.
Batteries need improvement in their wattage per kg and the energy density because there is a limited range of batteries at the moment
Energy density is the amount of energy stored in a given system or region of space per unit volume. It may also be used for energy per unit mass, though the accurate term for this is specific energy. In this report energy density will be energy per kg and the term is used to rate batteries.
A lot of energy in a small mass is desired for a battery as this will make devices even more portable.
High powered batteries are not necessarily the same as high energy density batteries. High power batteries will deliver energy more quickly than low power batteries.
A large energy density battery is desired for a car in order to drive further on a single charge without having a large, heavy battery.
Professor Corr’s talk mostly concentrated on the chemical and material aspect of research into batteries, but designing and developing battery architecture is also an ongoing project. This is to improve energy densities.
So, what do batteries do?
Batteries are used to power portable devices and are being increasingly used in transport.
Research is also going on to make a fully electric aircraft.
An electric aircraft is an aircraft powered by electric motors. Electricity may be supplied by a variety of methods including batteries, ground power cables, solar cells, ultracapacitors, fuel cells and power beaming.
Small, electrically powered model aircraft have been flown since the 1970s, with one unconfirmed report as early as 1957. They have since developed into small unmanned aerial vehicles (UAV) or drones, which in the twenty-first century have become widely used for many purposes.
In 2016, Solar Impulse 2 was the first solar-powered aircraft to complete circumnavigation of the world.
Batteries are the most common energy carrier component of electric aircraft, due to their relatively high capacity.
What is the challenge and why are new batteries being hunted?
Well we know when we use our laptops, mobile phone and any other portable devices continuously during the day they will start to “fade”.
Also, after a few months these devices will not hold charge as well as they did when they were first bought.
The reason for these events is complex and there are many processes going on inside the battery and numerous materials involved.
Materials in the battery can degrade over time and this impacts negatively on its performance.
What the researchers are interested in is how the degradation processes happen. Understanding these can lead to ways of improving batteries.
Researchers also want to discover and develop new electrolytes that will improve battery performance and lead to better batteries in the future.
An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent. Electrically, such a solution is neutral. If an electric potential is applied to such a solution, the cations of the solution are drawn to the electrode that has an abundance of electrons, while the anions are drawn to the electrode that has a deficit of electrons. The movement of anions and cations in opposite directions within the solution amounts to a current. This includes most soluble salts, acids, and bases. Some gases, such as hydrogen chloride, under conditions of high temperature or low pressure can also function as electrolytes. Electrolyte solutions can also result from the dissolution of some biological (e.g., DNA, polypeptides) and synthetic polymers (e.g., polystyrene sulfonate), termed “polyelectrolytes”, which contain charged functional groups. A substance that dissociates into ions in solution acquires the capacity to conduct electricity. Sodium, potassium, chloride, calcium, magnesium, and phosphate are examples of electrolytes.
A polar molecule is one that has a net neutral charge but has positive and negative regions. A water molecule is a very good example
The research that Professor Corr is carrying out is done in association with the Faraday institution.
What is the Faraday Institution?
Founded in October 2017, the Faraday Institution is the UK’s independent institute for electrochemical energy storage science and technology, supporting research, training, and analysis.
Bringing together expertise from universities and industry, and as part of the Faraday Battery Challenge, the Faraday Institution endeavours to make the UK the go-to place for the research, development, manufacture and production of new electrical storage technologies for both the automotive and the wider relevant sectors.
The Faraday Institution funds application-inspired basic research in electrochemical energy storage. The most promising research coming out of the Institution will be developed for real-world use through the pipeline of innovation and application established through the Faraday Battery Challenge. This model will discover new materials, leading to game-changing tech breakthroughs.
The Faraday Institution brings together scientists, industry partners, and government funding with a common goal. We invest in collaborative research to reduce battery cost, weight, and volume; to improve performance and reliability; to develop scalable designs; to improve our manufacturing; to develop whole-life strategies from mining to recycling to second use; and to accelerate commercialisation.
They will develop a National Skills Framework for the auto sector, to prepare regional and national workforces for the transition to a fully electric future. This will provide new models of education and training for skilled workers while creating new and expanded employment.
Some of the activities the Faraday Institution is involved with
1) Extending battery life
The many possible causes of performance degradation in lithium ion batteries and the comprehensive suite of techniques being used to unravel their mechanisms.
Degradation mechanisms can occur on length-scales from the nano to the macroscopic, and timescales from seconds up to years; a full understanding of the causes and effects of degradation of lithium ion batteries for vehicle applications requires a collaborative investigation across these length and time scales and with the combination of many experimental techniques. In other words, understanding the process of degradation can lead to strategies that alleviate the problem.
2) Multi-scale modelling
To advance current models and develop design tools which can accurately predict the performance and lifetime of existing and future batteries requires a fully integrated and tightly coordinated programme, drawing together the key modelling capabilities into a multi-scale approach, across length and time scales.
The performance and lifetime of a battery in an electric vehicle (EV) depends not only on the underlying chemistry and physics. The way in which the cells are combined into a pack large enough to power an EV and the mechanism controlling the local environment of each cell within that pack also influence lifetime and performance.
Accurate simulations of batteries help to design advanced batteries without the cost of creating numerous prototypes to test every new material, or new type and configuration of the cells which make up a pack. Simulations also offer valuable insight into how existing materials work, enabling identification of the limiting processes and the development of rational strategies to overcome them or to the design of new materials, leading to significant improvements of battery performance and lifetime. Models for control will also enable the lifetime and/or performance to be extended and reduce the cost of existing and future packs.
3) Electrode manufacturing
Develop new methods of manufacturing electrodes to give a longer range and increased durability.
There are two major projects involved in this research. Finding alternative chemistries that could enable greater energy densities, a reduction in costs and prolonged lifetimes. Looking for alternatives to lithium ion electrodes. These include solid state batteries as using lithium metal could increase the range and make the batteries lighter
Schematic cross-section of a Li-ion battery electrode showing some of the smart possibilities to be investigated by Nextrode.
4) Lithium cathode material
The next generation of Li-ion batteries must have longer lifespans and increased energy density to increase the range of electric vehicles. The biggest performance gains are likely to arise from changes to the cathode chemistry. And crucially – because of the cost, sustainability and ethical concerns surrounding cobalt – battery technology must be based around alternatives to the traditional cobalt containing cathodes.
Some of the areas of research that FutureCat is particularly investigating are materials with controlled or ordered structures (that enable use of otherwise unstable materials, provide mechanical stability, increase battery durability or open new pathways for development) and synthesis methods that may be a route to new materials through inexpensive processes (reducing battery prices).
5) Sodium ions batteries
The sodium-ion battery (NIB) is a type of rechargeable battery analogous to the lithium-ion battery but using sodium ions (Na+) as the charge carriers. The development is being accelerated as it is expected to be a low-cost alternative to lithium batteries.
Most current generation rechargeable batteries for transportation are based on the use of lithium. However, the relatively high cost, the somewhat limited global abundance of lithium, and environmental concerns around the sourcing of lithium mean that there is demand for a lower cost alternative that would increase the uptake of energy storage technologies in a number of sectors. Sodium-based batteries could be such an option, particularly for static storage, where cost is a more important factor than weight or performance.
Milestones (to September 2023):
• Discover and develop innovative electrode materials for higher performance, lower cost Na-ion batteries.
• Discover and develop next-generation electrolyte materials, giving higher sodium mobility and therefore higher power.
• Refine the test and characterisation methods most applicable for materials for Na-ion batteries.
6) Solid state batteries
A solid-state battery is a battery technology that uses solid electrodes and a solid electrolyte, instead of the liquid or polymer gel electrolytes found in lithium-ion or lithium polymer batteries. Materials proposed for use as solid electrolytes in solid-state batteries include ceramics (e.g. oxides, sulfides, phosphates), and solid polymers. Solid-state batteries have found use in pacemakers, RFID and wearable devices. They are potentially safer, with higher energy densities, but at a much higher cost.
Challenges to widespread adoption include energy and power density, durability, material costs, sensitivity and stability
An all-solid-state battery would revolutionise the electric vehicles of the future. The successful implementation of an alkali metal negative electrode and the replacement of the flammable organic liquid electrolytes, currently used in Li-ion batteries, with a solid would increase the range of the battery and address the safety concerns. Current efforts to commercialise such batteries worldwide are failing and will continue to fail until we understand the fundamental processes taking place in these devices.
7) Lithium sulfur batteries
The lithium–sulfur battery (Li–S battery) is a type of rechargeable battery, notable for its high specific energy. The low atomic weight of lithium and moderate atomic weight of sulfur means that Li–S batteries are relatively light (about the density of water). They were used on the longest and highest-altitude unmanned solar-powered aeroplane flight (at the time) by Zephyr 6 in August 2008.
Lithium sulfur batteries are expected to give improvements in specific energy densities and can be used over an increased temperature range than other batteries. There are cost and safety benefits as well. The cost of raw materials is lower. There is also a reduced environmental burden associated with the cell materials.
8) A vitally important project underpinning all of the institution’s work is the recycling and re-use of batteries. This involves establishing the necessary technological, economic and legal structure that can support the recycling of materials that make up batteries.
The key components of the project are:
• a ‘triage’ system for used battery assessment
• fully autonomous gateway testing and robotic sorting
• an assessment of the relative engineering and economic gains for various second life applications
• the development of recycling technologies to segregate and purify the different materials into a useful form for re-use in batteries or other applications
• life cycle analysis and techno-economic assessment of each recycling route developed
• development of new business models to promote the collection and sorting of batteries
• review of the regulatory framework for battery recycling in the UK and analysis of which EU waste laws should be retained law in the UK after Brexit
• full characterisation of active materials from cells near and at end of life and recycled materials recovered from used batteries, with respect to chemical composition (elemental concentration and distribution), particle size and morphology.
The overall aim of the ReLiB project is to understand the conditions required to ensure the sustainable management of lithium-ion batteries when they reach the end of their useful life in electric vehicles.
Since many of the components in batteries are made from valuable elements with special properties, which should not be disposed of as waste, it makes sense to explore how these could be recovered from end-of-life batteries to develop a system for re-circulating this material for new battery production. This would reduce the demand for imported primary materials and would also enhance the security of supply and material efficiency.
9) There are exciting developments in computational tools that can help predict new materials and help in the understanding of the mechanisms of how new batteries can work as well as new characterisation and diagnostic tools for investigating batteries.
All the projects mentioned are bringing together hundreds of experts and researchers across the UK in a highly collaborative manner.
Professor Corr is leading one of the projects on next generation cathode materials called FutureCat.
– The Faraday Institution’s collaborative FutureCat project has set out to develop cathode materials to drive the transition towards electric vehicles –
– Developing cathodes that hold more charge and withstand prolonged cycling –
– Promote ion mobility to increase durability, range and acceleration for the electric vehicle market –
The group consists of over 50 researchers working on the next generation of lithium cathodes. Looking at new synthesis routes to cathodes, discovering brand new chemistries and applying advanced characterisation techniques and computational tools to understand and manipulate the materials involved.
The group is working very closely with industry to make sure the materials they are making and developing are actually meeting the needs of industry.
In order to understand where the research is going it is important to understand where it started from.
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell’s equations. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others.
1) Long before any knowledge of electricity existed, people were aware of shocks from electric fish.
Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, could be rubbed with cat’s fur to attract light objects like feathers.
2) Electricity would remain little more than an intellectual curiosity for millennia until 1600, when the English scientist William Gilbert wrote De Magnete, in which he made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber.
William Gilbert (24 May 1544? – 30 November 1603), also known as Gilberd, was an English physician, physicist and natural philosopher.
3) Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. In June 1752 he is reputed to have attached a metal key to the bottom of a dampened kite string and flown the kite in a storm-threatened sky. A succession of sparks jumping from the key to the back of his hand showed that lightning was indeed electrical in nature. He also explained the apparently paradoxical behaviour of the Leyden jar as a device for storing large amounts of electrical charge in terms of electricity consisting of both positive and negative charges.
Benjamin Franklin FRS FRSA FRSE (January 17, 1706 [O.S. January 6, 1705] – April 17, 1790) was an American polymath and one of the Founding Fathers of the United States.
A Leyden jar (or Leiden jar) is an antique electrical component which stores a high-voltage electric charge (from an external source) between electrical conductors on the inside and outside of a glass jar. It typically consists of a glass jar with metal foil cemented to the inside and the outside surfaces, and a metal terminal projecting vertically through the jar lid to make contact with the inner foil.
4) In 1791, Luigi Galvani published his discovery of bioelectromagnetics, demonstrating that electricity was the medium by which neurons passed signals to the muscles.
Luigi Galvani (9 September 1737 – 4 December 1798) was an Italian physician, physicist, biologist and philosopher, who discovered animal electricity.
Late 1780s diagram of Galvani’s experiment on frog legs
The beginning of Galvani’s experiments with bioelectricity has a popular legend which says that Galvani was slowly skinning a frog at a table where he and his wife had been conducting experiments with static electricity by rubbing frog skin. Galvani’s assistant touched an exposed sciatic nerve of the frog with a metal scalpel that had picked up a charge. At that moment, they saw sparks and the dead frog’s leg kicked as if in life. The observation made the Galvanis the first investigators to appreciate the relationship between electricity and animation—or life. This finding provided the basis for the new understanding that the impetus behind muscle movement was electrical energy carried by a liquid (ions), and not air or fluid as in earlier balloonist theories.
Galvani coined the term animal electricity to describe the force that activated the muscles of his specimens. Along with contemporaries, he regarded their activation as being generated by an electrical fluid that is carried to the muscles by the nerves. The phenomenon was dubbed galvanism, after Galvani and his wife, on the suggestion of his peer and sometime intellectual adversary Alessandro Volta. The Galvanis are properly credited with the discovery of bioelectricity. Today, the study of galvanic effects in biology is called electrophysiology, the term galvanism being used only in historical contexts.
Electrodes touch a frog, and the legs twitch into the upward position
5) Alessandro Volta’s battery, or voltaic pile, of 1800, made from alternating layers of zinc and copper, provided scientists with a more reliable source of electrical energy than the electrostatic machines previously used.
Alessandro Giuseppe Antonio Anastasio Volta (18 February 1745 – 5 March 1827) was an Italian physicist, chemist, and pioneer of electricity and power who is credited as the inventor of the electric battery.
He invented the Voltaic pile in 1799, and reported the results of his experiments in 1800 in a two-part letter to the President of the Royal Society. With this invention Volta proved that electricity could be generated chemically and debunked the prevalent theory that electricity was generated solely by living beings.
Volta realised that the frog’s leg served as both a conductor of electricity (what we would now call an electrolyte) and as a detector of electricity. He also understood that the frog’s legs were irrelevant to the electric current, which was caused by the two differing metals. He replaced the frog’s leg with brine-soaked paper, and detected the flow of electricity by other means familiar to him from his previous studies. In this way he discovered the electrochemical series, and the law that the electromotive force (emf) of a galvanic cell, consisting of a pair of metal electrodes separated by electrolyte, is the difference between their two electrode potentials (thus, two identical electrodes and a common electrolyte give zero net emf). This may be called Volta’s Law of the electrochemical series.
In 1800, as the result of a professional disagreement over the galvanic response advocated by Galvani, Volta invented the voltaic pile, an early electric battery, which produced a steady electric current. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and copper. Initially he experimented with individual cells in series, each cell being a wine goblet filled with brine into which the two dissimilar electrodes were dipped. The voltaic pile replaced the goblets with cardboard soaked in brine.
The voltaic pile was the first electrical battery that could continuously provide an electric current to a circuit. It was invented by Italian physicist Alessandro Volta, who published his experiments in 1799. The voltaic pile then enabled a rapid series of other discoveries including the electrical decomposition (electrolysis) of water into oxygen and hydrogen and, the discovery or isolation of the chemical elements sodium, potassium, calcium, boron, barium, strontium, and magnesium.
The entire 19th-century electrical industry was powered by batteries related to Volta’s cell until the advent of the dynamo (the electrical generator) in the 1870s.
Volta’s invention was built on Luigi Galvani’s 1780s discovery of how a circuit of two metals and a frog’s leg can cause the frog’s leg to respond. Volta demonstrated in 1794 that when two metals and brine-soaked cloth or cardboard are arranged in a circuit they produce an electric current. In 1800, Volta stacked several pairs of alternating copper (or silver) and zinc discs (electrodes) separated by cloth or cardboard soaked in brine (electrolyte) to increase the electrolyte conductivity. When the top and bottom contacts were connected by a wire, an electric current flowed through the voltaic pile and the connecting wire.
Volta had realised that different metals had different electrical effects, but at this time electrons, atoms, and ions were not known.
The combination of certain different metals gave an obvious electric current. Different metals had different electrical effects.
Schematic diagram of a copper–zinc voltaic pile. The copper and zinc discs were separated by cardboard or felt spacers soaked in salt water (the electrolyte). Volta’s original piles contained an additional zinc disk at the bottom, and an additional copper disk at the top. These were later shown to be unnecessary.
Volta did not consider the electrolyte, which was typically brine in his experiments, to be significant. However, chemists soon realized that water in the electrolyte was involved in the pile’s chemical reactions (the process was happening at the interface between electrolyte and metal), and led to the evolution of hydrogen gas from the copper or silver electrode
The modern, atomic understanding of a cell with zinc and copper electrodes separated by an electrolyte is the following. When the cell is providing an electrical current through an external circuit, the metallic zinc at the surface of the zinc anode is oxidised and dissolves into the electrolyte as electrically charged ions (Zn2+), leaving 2 negatively charged electrons (e−) behind in the metal:
This reaction is called oxidation. Now this might surprise some of you because no oxygen is involved. The term, in this context, means zinc is losing electrons and is becoming a positive zinc ion. While the zinc ion is entering the electrolyte, two positively charged hydrogen ions (H+) from the electrolyte (remember that brine is simply a solution of sodium and chlorine ions in water, and the hydrogen comes from the water) accept two electrons at the copper cathode surface, become reduced and form an uncharged hydrogen molecule (H2):
This reaction is called reduction. The electrons used from the copper to form the molecules of hydrogen are made up by an external wire or circuit that connects it to the zinc. This wire attached to both ends of the pile, produces a steady current. The hydrogen molecules formed on the surface of the copper by the reduction reaction ultimately bubble away as hydrogen gas.
The global electro-chemical reaction does not immediately involve the electrochemical couple Cu2+/Cu (Ox/Red) corresponding to the copper cathode. The copper metal disk thus only serves here as a “chemically inert” noble metallic conductor for the transport of electrons in the circuit and does not chemically participate in the reaction within the aqueous phase. The copper electrode could be replaced in the system by any sufficiently noble/inert metallic conductor (Ag, Pt, stainless steel, graphite, …). The global reaction can be written as follows:
The voltaic pile works on the basis that some elements are more electropositive than others. Electropositive elements lose electrons more readily than other elements. Copper is more electronegative because it attracts electrons more readily than other elements.
The electrochemical series above has the most electropositive element at the top and the least at the bottom. Zinc is higher in the electrochemical series than copper. So, electrons move away from zinc, along the external wire, to copper.
The more electrons that flow in the external wire the greater the current
A voltmeter can measure the potential difference across the pile. This a measure of the work needed per unit charge to move the electrons in the external wire. The electrons are moving away from zinc, through the wire, to the copper because of the potential difference (this potential difference arises because zinc and copper have different electrochemistry).
Different metals combined in an electrochemical cell can produce different potential differences (the unit of this is the volt, named after Volta).
The voltaic pile was important in that scientists has a ready source of electricity for the first time.
Batteries use chemistry (and because chemistry is just a minor branch of physics, they use physics too)
Batteries are a store of energy and the energy is stored in the chemicals inside them. The term that chemists use is chemical potential energy. Physics is in the process of changing energy definitions, but I am sticking with the chemistry.
When the battery is connected to an external circuit this energy can be transformed into other forms.
An analogy to this would be jumping in the air. Energy stored in the food you’ve eaten is transferred to gravitational potential energy when you have jumped up. So, in simple terms chemical potential energy has been transformed to gravitational potential energy.
Professor Corr visited a primary school and invited a class to do some jumping.
The formula for gravitational potential energy PE is mgh where m is the mass, g is the gravitational field strength (9.8N/Kg on Earth) and h is the height of the jump from the ground.
PE = mgh
Say the mass of one child is 20kg and the height the child jumps is 0.2m
So. PE = 20 x 9.8 x 0.2 = 39.2J per child
If there are 30 children jumping up
PE = 39.2 x 30 = 1176J
If all the children do 30 jumps the PE = 1176 x 30 = 35280J or 35.3kJ
Power is work done per unit time. The children did their jumps in 15 seconds so their power in kilowatts (kW) = 35.3kJ/15s = 2.35kW
Whilst Professor Corr was at the school she asked the children what batteries were used for. They mostly said that they were used for toys.
Batteries store energy for when it is needed. The children’s jumping was showing an energy transfer. Chemical energy used to provide kinetic energy for movement which is transferred to gravitational potential energy when the children jump up.
The 2.35kW of the children is equivalent to the average power consumed by an electric kettle.
Now it wouldn’t be ethical to get children to jump up to power a kettle so other methods of producing and storing electricity are needed.
Another energy transfer can be found in cars.
In a petrol/diesel run car the chemical potential energy store is the fuel. The car ignition provided the spark that allows the fuel-air mixture to burn. The chemical potential energy is converted to kinetic energy and the wheels move.
For an electric vehicle the chemical potential energy is inside the batteries, which when switched on, causes an electric motor to work and the wheels turn,
Battery powered car.
Electricity meets chemistry and physics
Charles-Augustin de Coulomb (14 June 1736 – 23 August 1806) was a French military engineer and physicist. He is best known as the discoverer of what is now called Coulomb’s law, the description of the electrostatic force of attraction and repulsion.
The SI unit of electric charge, the coulomb, was named in his honour in 1908.
7) Michael Faraday
Michael Faraday FRS (22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic induction, diamagnetism and electrolysis.
Electrochemistry is the branch of physical chemistry that studies the relationship between electricity, as a measurable and quantitative phenomenon, and identifiable chemical change, with either electricity considered an outcome of a particular chemical change or vice versa. These reactions involve electric charges moving between electrodes and an electrolyte (or ionic species in a solution). Thus, electrochemistry deals with the interaction between electrical energy and chemical change.
When a chemical reaction is caused by an externally supplied current, as in electrolysis, or if an electric current is produced by a spontaneous chemical reaction as in a battery, it is called an electrochemical reaction. Chemical reactions where electrons are transferred directly between molecules and/or atoms are called oxidation-reduction or redox reactions. In general, electrochemistry describes the overall reactions when individual redox reactions are separate but connected by an external electric circuit and an intervening electrolyte.
Faraday is best known for his work regarding electricity and magnetism. His first recorded experiment was the construction of a voltaic pile with seven British halfpenny coins, stacked together with seven disks of sheet zinc, and six pieces of paper moistened with salt water. With this pile he decomposed sulfate of magnesia (12 July 1812).
In 1832, Michael Faraday’s experiments led him to state his two laws of electrochemistry.
Michael Faraday reported that the mass (m) of elements deposited at an electrode in grams (g) is directly proportional to the Charge (Q) in Coulombs. Charge = current (A) x time (s)
Here, the constant of proportionality Z is called the Electro-Chemical Equivalent (e.c.e) of the substance. Thus, the e.c.e. can be defined as the mass of the substance deposited/liberated per unit charge.
Faraday discovered that when the same amount of current is passed through different electrolytes/elements connected in series, the mass of the substance liberated/deposited at the electrodes in g is directly proportional to their chemical equivalent/equivalent weight (E). This turns out to be the molar mass (M) divided by the valence (v)
Capacity is a measure of charge stored in the battery and it depends on the mass of the active material in the battery. It is also the amount of electric charge it can deliver at the rated voltage. The more electrode material contained in the cell the greater its capacity.
The specific capacity is Amp-hours per gram = valence of the material (n) x Faraday constant (F)/number of moles (M)
Note: charge = current (Amp) x time and the time unit is normally in seconds. But for capacity the time unit is the hour.
Faraday’s work showed that the processes in the cell were chemical in nature following his work on electrolysis. He gave the names to the parts of the battery we know today. Electrode, cathode, anode, electrolyte, ions, cations and anions, He discovered that the source of electricity or emf was from the chemical reactions that were occurring at the electrode/electrolyte surface.
We can use Faraday’s laws to determine quantitative information about batteries today.
The equation above is used to calculate the specific storage capacity of a battery.
How do batteries work?
A battery is usually defined as containing two or more identical cells, each of which stores electric power as chemical energy. Each cell contains two electrodes separated by an electrolyte.
The electrode of a battery that releases electrons during discharge is called the anode; the electrode that absorbs the electrons is the cathode.
The battery anode is always negative and the cathode positive. This appears to violate the convention as the anode is the terminal into which current flows. A vacuum tube, diode or a battery on charge follows this order, however taking power away from a battery on discharge turns the anode negative. Since the battery is an electric storage device providing energy, the battery anode is always negative.
The cathode of a battery is positive and the anode is negative
The reaction between these electrodes is both electronic and ionic.
Chemical reactions cause a build-up of electrons at the anode. When the cathode and anode are connected to an external electric circuit the electrons can flow through this external circuit and perform a function such as lighting up a bulb. The electrolyte prevents electrons moving straight back to the cathode through the battery.
What about rechargeable lithium ion batteries? How did they come about?
The idea of rechargeable batteries is not new. In 1859, Gaston Planté invented the lead–acid battery, the first-ever battery that could be recharged by passing a reverse current through it.
In 1866, Georges Leclanché invented a battery that consisted of a zinc anode and a manganese dioxide cathode wrapped in a porous material, dipped in a jar of ammonium chloride solution. It provided a voltage of 1.4V and achieved very quick success in telegraphy, signalling, electric bell work and early telephones. However, it could not provide a sustained current for very long. In lengthy telephone conversations, the battery would run down, rendering the conversation inaudible. This is because certain chemical reactions in the cell increased the internal resistance and, thus, lowered the voltage. These reactions reversed themselves when the battery was left idle, so it was good only for intermittent use.
In 1899, a Swedish scientist named Waldemar Jungner invented the nickel–cadmium battery, a rechargeable battery that has nickel and cadmium electrodes in a potassium hydroxide solution; the first battery to use an alkaline electrolyte.
Experimentation with lithium batteries began in 1912 under G.N. Lewis, but commercial lithium batteries did not come to market until the 1970s.
Lithium batteries were proposed by British chemist M. Stanley Whittingham, now at Binghamton University, while working for Exxon in the 1970s
Michael Stanley Whittingham (born 22 December 1941) is a British-American chemist.
Exxon is the brand name of oil and natural resources company Exxon Corporation, prior to 1972, known as Standard Oil Company of New Jersey.
It might seem rather surprising that a fossil fuel company would be interested in rechargeable batteries, but there are several reasons why the 1970s prompted this research:
More battery powered equipment was becoming portable. If the batteries are rechargeable then you need a supply of electricity and in the 1970s fossil fuels were needed to produce the electricity;
By the 1970s it was realised that fossil fuels were running out so any fossil fuel company would be looking for new avenues to make money;
In 1973 Arab states led by Egypt went to war against Israel and the price of oil quadrupled. In the UK there were power cuts and the workforce embarked on a three-day working week. This prompted research into renewable energy resources.
In his initial research, Whittingham used titanium (IV) sulfide and lithium metal as the electrodes. He was interested in demonstrating that lithium ions could be reversibly inserted into the titanium (which is a transition metal) di-sulphide layers.
However, this rechargeable lithium battery could never be made practical. Titanium disulfide was a poor choice, since it has to be synthesized under completely sealed conditions, also being quite expensive (~$1,000 per kilogram for titanium disulfide raw material in 1970s). When exposed to air, titanium disulfide reacts to form hydrogen sulfide compounds, which have an unpleasant odour and are toxic to most animals.
Another issue with this battery were lithium dendrites, which could grow across the cell, through the electrolyte, touching the cathode and causing a short circuit. This was a potential fire hazard with the flammable organic electrolyte.
For these reasons, Exxon discontinued development of Whittingham’s lithium-titanium disulfide battery. Batteries with metallic lithium electrodes presented safety issues, as lithium metal reacts with water, releasing flammable hydrogen gas.
At about the same time as Whittingham was working on his battery John B. Goodenough (Oxford University) was experimenting with transition metal oxides to see whether a discharged state could be achieved with lithium and whether the lithium ions could be reversibly extracted. He also predicted that the cathode could have an even greater potential if it as made out of an oxide instead of a sulphide.
In 1979 Goodenough and Koichi Mizushima (Tokyo University), demonstrated a rechargeable lithium cell with voltage in the 4 V range using lithium cobalt dioxide (LiCoO2) as the positive electrode and lithium metal as the negative electrode. This innovation provided the positive electrode material that enabled early commercial lithium batteries. LiCoO2 is a stable positive electrode material which acts as a donor of lithium ions, which means that it can be used with a negative electrode material other than lithium metal. By enabling the use of stable and easy-to-handle negative electrode materials, LiCoO2 enabled novel rechargeable battery systems. They also demonstrated that with the LiCoO2 cathode half of the lithium could be extracted reversibly,
John Bannister Goodenough (born July 25, 1922) is an American materials scientist, a solid-state physicist, and a Nobel laureate in chemistry.
Koichi Mizushima (born January 30, 1941) is a Japanese researcher known for discovering lithium cobalt oxide (LiCoO2) and related materials for the lithium-ion battery (Li-ion battery).
In 1980 Rachid Yazami demonstrated the reversible electrochemical intercalation of lithium in graphite and invented the lithium graphite electrode (anode). The organic electrolytes available at the time would decompose during charging with a graphite negative electrode. Yazami used a solid electrolyte to demonstrate that lithium could be reversibly intercalated (inserted) in graphite through an electrochemical mechanism. As of 2011, Yazami’s graphite electrode was the most commonly used electrode in commercial lithium-ion batteries.
Rachid Yazami is a Moroccan scientist and engineer. He is best known for his critical role in the development of the lithium-ion battery, as the inventor of the graphite anode (negative pole) of lithium-ion batteries. He is also known for his research on fluoride ion batteries.
Batteries containing a lithium ion cathode and a graphite anode were used to power the early mobile phones.
Charging and discharging in lithium ion/graphite batteries
During charging the cathode is giving up some of its lithium ions (green circles), which move through the electrolyte to the negative graphite electrode. During this process the battery is taking in and storing energy.
When the battery is discharging the lithium ions are moving back through the electrode to the positive electrode. This produces the energy that powers the battery. In both cases the electrons are flowing in the opposite direction to the ions, in the external circuit. Electrons don’t flow through the electrolyte, only the ions do.
The processes are reversible and the battery is rechargeable.
This inspirational, pioneering work, which is still ongoing, is of enormous benefit for the human race. The Nobel prize for chemistry in 2019 was awarded for the research into these batteries.
The Nobel Prize in Chemistry 2019 was awarded jointly to John B. Goodenough, M. Stanley Whittingham and Akira Yoshino “for the development of lithium-ion batteries.”
Akira Yoshino (born 30 January 1948) is a Japanese chemist. He is a fellow of Asahi Kasei Corporation and a professor at Meijo University in Nagoya. He created the first safe, production-viable lithium-ion battery which became used widely in cellular phones and notebook computers. Yoshino was awarded the Nobel Prize in Chemistry in 2019 alongside M. Stanley Whittingham and John B. Goodenough.
The next 20-year targets for batteries
The image above shows the ongoing collaborative research topics
1) Reduce cost – reduce the reliance on expensive materials and move to cheaper, more sustainable materials
2) Safety – in 2016 Samsung galaxy note 7 had to be recalled because the battery overheated with a tendency to combust or explode
So, research is being carried out to make batteries safer.
3) Improvement in extending the first life of a battery
4) Improving the recycling of the batteries and the materials that make up the batteries
5) Energy density and power density are two parameters used to evaluate a battery’s performance.
If the battery is high energy density it is capable of storing a lot of energy. Mobile phone batteries are high energy density batteries. The phones can be used for most of a day without needing to be recharged. When they have completely rundown, they can be recharged in a few hours
Power density is a measure of how much power a battery can deliver on demand.
A high energy density battery doesn’t necessarily mean it has a high-power density.
Difference between energy and power
L’Alpe d’Huez is climbed regularly in the Tour de France. The yellow in the above image shows cyclists’ route but their potential energy simply depends on the vertical height (gain in altitude)
Potential energy of the cyclist = mgh
Mass of rider and bike = m = 90kg
Gravitational field strength = g = 9.8N/kg
Change in altitude = h = 1830m above sea level – 713m above sea level = 1127m
Potential energy gained by the cyclist = 90 x 9.81 x 1127 = 994000J = 994kJ
= the work done in climbing the mountain
It took the cyclist 1 hour and 52 minutes (6720 seconds) to do the climb
The average power of the cyclist = work done/time taken = 994000/6720 = 147W
The cyclist needs to keep his power output at a reasonable value because he is cycling for nearly two hours.
However, if the cyclist is exercising by sitting on a static bike and doesn’t want to sit on it for two hours, he can reach powers of between 500 and 1000W. Even a very fit cyclist can only maintain these powers for a few seconds.
High power density batteries can give short bursts of high power. This would be useful in a power tool.
Commercial lithium ion batteries are produced for either high energy density or high-power density.
Sometimes battery materials can be tailored by thinking about the morphology of the materials and how they might influence the power or energy characteristics.
To improve a specific characteristic like energy density, the materials used may need to be changed.
A material that is increasingly being used in electric vehicles is nickel.
Improving energy densities
The above structure of the NMC cathode looks like the lithium cobalt dioxide structure written about earlier.
The blue layers are made up of the transition elements, the oxygen ions are orange and the lithium ions, occupying the space between the layers, are green.
Cobalt can be replaced by other metals such as manganese, nickel and aluminium. This is important as it will reduce the dependency of expensive, toxic elements like cobalt
There is also the ethical concern in the mining of cobalt.
Manganese stabilises the structure of the NMC cathode.
Increasing the nickel content improves the energy density of the battery and increases the amount of lithium recycled in and out of the cathode.
Interview with Dr Beth Johnston
Developing new cathode materials for lithium ion batteries
1) Why is there such an interest in high nickel cathodes?
When the amount of nickel is increased the capacity of the cathodes increases. This can increase the energy density of the battery. Energy density is the key.
2) What about the other elements that are contained in the cathode material?
Modern batteries rely on nickel and cobalt and the drive is to reduce or remove cobalt. The reasons for removing cobalt is that it isn’t found in many places, it’s expensive, toxic, there are supply chain issues and there are ethical issues around its mining.
Removing the cobalt should make the battery production more sustainable. Increasing the quantity of nickel means the amount of cobalt ca be reduced
3) Is it as simple as removing cobalt and adding nickel. Increasing the amount of nickel in the cathodes using the same synthesis procedures.
No, not quite. As the nickel content is increased the synthesis has to slightly change. The chemistry of the material slightly changes and a few challenges occur along the way if more nickel is to be incorporated into the material. Facing these challenges and solving them is part of Dr Johnston’s research.
4) Explain some of the research you are doing to make some of these next generation high nickel content cathodes.
The research focuses mainly on the synthesis in these procedures that are used to make the materials and finding easier routes to the beautiful layered structures involving lithium and nickel. This is to enable the lithium ions to move easily in and out of the material during the charging and discharging of the battery. One of the ways this is being done is to investigate the use of microwaves during the synthesis process. Microwaves can really reduce the amount of side reactions to the main reaction, making the nice layered structures that lithium can move nicely in and out of.
Microwaves can also allow the desired reactions to occur at lower temperatures and shorter times, giving a more economical route to the synthesis which is important when scaling up the processes to make lots of cathode material. A key consideration for industry
5) Are there any other families of cathodes that the team is exploring?
Yes. An increasing interest in disordered, layered rock salt cathode.
These rely on manganese rather than cobalt and nickel. Manganese is abundant, cheap and very safe. There is interest because they will make more sustainable cathodes in the future.
At the moment it is an emerging cathode material but there are some challenges surrounding it stability and recycling. Dr Johnston’s research group is working with the Faraday institution on stabilising the disordered rock salts and creating more sustainable cathode of the future.
Back to Professor Corr
What are the issues with these new cathodes?
In reality lots of particles aggregate together which means there are grain boundaries as well as interfaces between the electrode and electrolyte. Also, there are often other materials like carbon in the mix. A highly complex system
There are many reactions occurring at the electrode-electrolyte interface.
When the battery is cycling there are often reactions happening at the interface and a layer can build up which is termed a solid electrolyte interface. It forms on the surface of the cathode as a result of the decomposition of the electrolyte.
The formation and growth of that kind of layer presents huge challenges to the research.
Can the nature of the layer be understood and can it be controlled?
Another important degradation process involves particle cracking. This can happen when a strain is placed on the cathode. The layers in the cathode have to move to accommodate the lithium ions passing in and out. This is what causes the strain on the cathode.
When cracks form, they start to expose more surface of the electrode and this gives more places for unwanted reactions to occur between the electrode and the electrolyte.
Research is finding ways of mitigating the cracking formation. A very rich area of ongoing research.
Dendrite formation is also a problem that needs to be faced if lithium metal is sued as the anode.
Lithium is very light and electropositive and to be able to use it could extend the range of the battery. However, using metallic lithium as an anode can result in the formation of dendrites, looking like whiskers of lithium that can grow from the anode through the electrolyte to the cathode. These can cause short circuits, with the possibility of fires.
With some emerging technologies there is the challenge of trying to understand the structures of the materials used. Sometimes these materials have atoms cropping up in some unexpected places exhibiting some disorder. Understanding the nature of this disorder and how it affects the battery’s performance is really important for realising new battery formation materials.
Ongoing research activities
Some examples of ongoing research are aimed at tackling specific challenges. They include things like finding new ways of making materials that can give control over the final particle’s shape and size.
Examples include looking at single crystal particles to see if that kind of morphology could mitigate or withstand cracking behaviour and protecting the cathode by adding a protective coating. It will be even better if this coating can actually be grown around the cathode.
In the above right image, the cathode is coloured orange and the protective coating is coloured purple/blue. The coating might prevent some of the unwanted side reactions and prevent the early aging of the cathode. This might prolong the battery lifetime and ultimately reduce the cost.
New ways of studying batteries
Advances are being made in how batteries are investigated whilst they are recycling. This will prevent the need to continuously recycle batteries and then take them apart in order to look at the small parts that are of interest.
The changes can now be monitored in the battery as they are happening, such as recycling.
Examples of investigations involve X-rays, which can follow the changes in the battery when it is recycling (not the same as taking batteries to the tip to be recycled).
Research is also interested in seeking out brand new chemistries. This is often done through chemical intuition but the power of computing really comes into its own here.
Interview with Professor Chris Pritchard
Interview about computational tools that can help with the search for new batteries
1) What sort of insights can computational tools give in the hunt for new batteries.
Over the last decade the amount of computing power available to all of us has grown astonishingly and it has allowed the computational studies of materials to be changed.
At the time of his PhD, Professor Pickard had to queue to use a workstation and was only able to work on one equation, that ended up being most of his PhD thesis.
The change came in the mid-2000s when many cheap high-performance computers became available and even standard computers could be used to do the calculations connected with material modelling calculations. Instead of doing just one calculation millions could be done. This computer modelling process was pioneered in the energy materials area of research by MIT, which became the materials project and inspired the materials genome initiative in the US.
Harnessing the power of supercomputing and state of the art electronic structure methods, the Materials Project provides open web-based access to computed information on known and predicted materials as well as powerful analysis tools to inspire and design novel materials.
The Materials Genome Initiative is a multi-agency initiative designed to create a new era of policy, resources, and infrastructure that support U.S. institutions in the effort to discover, manufacture, and deploy advanced materials twice as fast, at a fraction of the cost.
The modern quantum mechanical tools could allow screening through databases of known materials and pick out ones that had just the right properties. Several patented materials for new batteries have been taken out from this process. At the same time researchers, including Professor Pickard, in the field, mainly from physics backgrounds (yay) asked more fundamental questions. “How would an arrangement of atoms space themselves out if we knew nothing about the chemistry? Lets just let them operate under quantum mechanics processes and move around. Could we, without knowing anything, predict the structure of the different forms of carbon (diamond, graphite, buckyballs etc.)? This is known as structure prediction”.
There are different approaches to structure prediction but they are all based on the fundamental idea of building random structures and letting the computer use quantum mechanics rules to move them to their lowest energy configurations.
Doing this process once is likely to give a rubbish result, but doing it more than a thousand times will throw up more stable configurations. This allows the model to be tweaked and the low energy structures will become the common structure. This allows a confident statement to be made that the lowest energy configurations have been found along with some possible metastable phases as well, which are of interest.
For the last decade or so these structural prediction techniques have been used in high pressure physics. They were used to predict room temperature superconductors
Scientists have created a mystery material that seems to conduct electricity without any resistance at temperatures of up to about 15 °C. That’s a new record for superconductivity, a phenomenon usually associated with very cold temperatures. The material itself is poorly understood, but it shows the potential of a class of superconductors discovered in 2015.
The superconductor has one serious limitation, however: it survives only under extremely high pressures, approaching those at the centre of Earth, meaning that it will not have any immediate practical applications. Still, physicists hope it could pave the way for the development of zero-resistance materials that can function at lower pressures.
So high-temperature superconductors will be very useful if you intend having a trip to the centre of the Earth, but not really useful for everyday life.
Computation is easier with the high-pressure techniques that are encountered in batteries. He quantum mechanics and the approximations used in quantum mechanics is called density functional theory.
Density-functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body systems, in particular atoms, molecules, and the condensed phases.
There is one slight disadvantage. If all the atoms (ions) and electrons are squeezed close together and then the pressure is removed, dealing with the material under ambient conditions causes the charge density to go up and down very quickly/strongly and the approximation doesn’t catch the activity very well.
In energy materials, where transition metals and delocalised electrons are so important, density functional theory struggles. For a long while work using this theory wasn’t possible with the techniques available but now there are more quantum mechanical techniques that allow the energy calculations of these materials. The FutureCat Faraday project is biting the bullet by trying to deal with more complicated systems with more elements in them as battery materials typically have 3 or 4 processes going on at the same time. It is also trying to deal with difficult electronic structures. How electrons are arranged in the material.
A large amount of data is being generated by this research.
When the structure prediction was first started ten structures would be developed overnight and it was easy for one person to look through them, but now, hundreds of thousands are being produced and a single researcher can’t look at them all and sort by hand. This is where the new techniques in machine learning and AI come in to play. They give ways of summarising and reducing dimensionality of the data so they can be plotted on a screen allowing the possibility of inferences to be made based on the data.
2) What are the major challenges in the computational work with the sort of machine learning techniques outlined earlier? What challenges are the research group after?
The research group would like to help the experimentalists understand the experiments they have carried out. This is a responsive mode. The computation element can explain what has gone on.
The research group would also like to strike out on their own and carry out their own theoretical experiments on computers. This will allow mixing of all the elements that the experimentalist have stayed away from so far. They are hoping to show experimentalists that there is some promise of physical experiments from the computer experiments and they are hoping to encourage the experimentalists to carry out the experiments for real.
There is a challenge in dealing with systems with at least 4 elements in them. There are so many possibilities of different combination of elements together without getting into how they are arranged in space. What are the ratios that need to be considered?
Another challenge is that real battery materials are not made up of single crystals which means they have defects and grain boundaries.
A battery is made up of multiple different materials stuck together which means they have interfaces. Researchers would like to predict and understand the structure of these material interfaces, but this work involves a larger number of atoms than they’re used to and there are multiple ways in which the atoms are arranged. There is never enough computing power, at the moment, for them to solve this problem. The method does have a positive aspect because through different compositions the exploring of larger systems can be broken down into smaller chunks.
Supercomputers can usually cope with a multitude of calculations. Doubling the amount of computing power should double the amount of science discovered, but this isn’t always the case.
When a supercomputer is used to solve some problems in science, with more independent computing cores, some of the advantages are lost as time goes by. This isn’t an unsurmountable problem. Many different things can be tried.
Back to Professor Corr
Thinking about new chemistries and sustainable alternatives.
The smartphone is made up of some 30 elements – over half of which may give cause for concern in the years to come because of increasing scarcity. The issue of element scarcity cannot be stressed enough. With some 10 million smartphones being discarded or replaced every month in the European Union alone, care should be taken to properly recycle such items. Unless solutions are provided, many of the natural elements that make up the world around will run out – whether because of limited supplies, their location in conflict areas, or humans’ incapacity to fully recycle them.
Protecting endangered elements needs to be achieved on a number of levels. Do phones and other electronic devices need to be upgraded regularly? Recycling needs to be done correctly to avoid old electronics ending up in landfill sites or polluting the environment. On a political level, thee needs to be a greater recognition of the risk element scarcity poses, and moves need to be made to support better recycling practices and an efficient circular economy. Moreover, transparency and ethical issues need to be considered to avoid the abuse of human rights, as well as to allow citizens to make informed choices when purchasing smartphones or other electronics – as many of the elements required in electronics are imported from conflict zones.
The image above is an unusual depiction of the periodic table. It charts element sustainability. Green = plentiful supply; Orange = facing a threat from increased use; Red = very serious threat from increased use.
This knowledge allows suitable sustainable alternative battery alternatives to be found. One such alternative is an olivine structure.
Lithium iron phosphate (LFP) is an inorganic compound with the formula LiFePO4. It is a grey, red-grey, brown or black solid that is insoluble in water. The material has attracted attention as a component of lithium iron phosphate batteries, a type of Li-ion battery. This battery chemistry is targeted for use in power tools, electric vehicles, and solar energy installations. It is also used in OLPC XO education laptops.
Its structure is a useful contributor to the cathode of lithium rechargeable batteries. This is due to the olivine structure created when lithium is combined with manganese, iron, and phosphate. The olivine structures of lithium rechargeable batteries are significant, for they are affordable, stable, and can be safely stored as energy
The olivine structure is different to the layered structure described earlier There are channels through which lithium ions can move in and out during charging and discharging.
So far, the emphasis has been about batteries where the size is important. The sort of batteries needed for mobile phones. But what about large-scale energy stores? These sorts of batteries will be necessary for a more renewable energy future.
Stationary batteries need to be considered to provide greater flexibility in powering systems and enable the optimisation of renewable energy sources like solar photovoltaics or wind energy, after all it isn’t always sunny or windy.
A flow battery, or redox flow battery (after reduction–oxidation), is a type of electrochemical cell where chemical energy is provided by two chemical components dissolved in liquids that are pumped through the system on separate sides of a membrane. Ion exchange (accompanied by flow of electric current) occurs through the membrane while both liquids circulate in their own respective space. Cell voltage is chemically determined by the Nernst equation and ranges, in practical applications, from 1.0 to 2.43 volts.
The energy capacity is a function of the electrolyte volume and the power is a function of the surface area of the electrodes.
A typical flow battery consists of two tanks of liquids which are pumped past a membrane held between two electrodes.
Life-time and cost will be huge drivers of stationary battery research.
At Sheffield they’ve been developing a new microwave chemistry where they can make very small particles of lithium ion phosphate
The lithium iron phosphate battery (LiFePO4 battery) or LFP battery (lithium ferrophosphate), is a type of lithium-ion battery using LiFePO4 as the cathode material (on a battery this is the positive side), and a graphitic carbon electrode with a metallic backing as the anode. The energy density of LiFePO4 is lower than that of lithium cobalt oxide (LiCoO2) chemistry, and also has a lower operating voltage. The main drawback of LiFePO4 is its low electrical conductivity. Therefore, all the LiFePO4 cathodes under consideration are actually LiFePO4/C. Because of low cost, low toxicity, well-defined performance, long-term stability, etc. LiFePO4 is finding a number of roles in vehicle use, utility scale stationary applications, and backup power.
In the image below then are two images (a and b) which are electron micrographs of the material. c shows some electrochemical data used to evaluate the performance of the batteries.
Current is usually a measure of charge flowing per second but with batteries the time unit is the hour. Charge = current x time so the charge stored in a battery is measured in Ah
Charge and discharge rates of a battery are governed by C-rates. The capacity of a battery is commonly rated at 1C, meaning that a fully charged battery rated at 1Ah should provide 1A for one hour. The same battery discharging at 0.5C should provide 500mA for two hours, and at 2C it delivers 2A for 30 minutes. Losses at fast discharges reduce the discharge time and these losses also affect charge times.
A C-rate of 1C is also known as a one-hour discharge; 0.5C or C/2 is a two-hour discharge and 0.2C or C/5 is a 5-hour discharge. Some high-performance batteries can be charged and discharged above 1C with moderate stress.
Graph d is showing that the capacity of the battery drops as you decrease the time for the battery cycling (charging and discharging). The thick black line labelled 1C shows that even at 500 cycles the capacity does not drop for that battery.
Also, in the above image is a small picture of the Lab’s microwave “oven”. It is used to speed up reactions (not to heat up beans)
Beyond the lithium ion and more sustainable alternatives. An interview with Dr Nuria Tapia Ruiz.
Researching sodium ion batteries (NextGen)
1) What advantages do sodium ion batteries have over lithium ion batteries?
They are a low-cost alternative to lithium ion batteries. They are gaining importance because of concerns regarding increasing demand of electrification, the limited availability of lithium and problems with recycling.
At present only about 1% of lithium being used at the moment comes from recycling.
Sodium ion batteries are low in cost due to the abundance of sodium, which is the fourth most abundant element in the Earth’s crust. Also using aluminium/carbon connectors instead of copper decreases the cost as aluminium is 3 times cheaper than copper.
Sodium ion batteries have the added advantage of being safer so they can be transported and stored at zero volts – completely discharged without any safety issues.
However, there is a major disadvantage. Given the higher mass of sodium these batteries will only be used where the energy density is not a big concern i.e. large-scale energy storage necessary for renewable sources of electricity.
2) What are the major challenges with sodium ion batteries?
(a) To gain information about the solid electrode/electrolyte interface. It is complex and difficult to understand given the higher reactivity of sodium and the higher solubility of the solid electrolyte interface (SEI) products when compared to lithium, which makes it unstable and very difficult to characterise.
(b) Developing materials with high energy density. This is a problem because sodium is heavier than lithium and it gives a higher voltage. Therefore, a careful control of the material structure will be needed in order to deliver comparable energy densities of lithium ion batteries.
3) Could you talk about the consortium you work with on this at Lancaster University.
They are designing new electromaterials for cathodes and anodes with special focus on layered transition elements, using transition elements that are abundant and low cost, such as iron, manganese, titanium and copper, and have the potential to produce high energy densities and high power.
Recently the group started working with hard carbons which are currently the state-of-the-art anodes in sodium ion batterie. Mixing these with metals to deliver higher energy densities than hard carbon alone.
All these activities contribute to the research taking place at NEXGENNA, a Faraday institution funded project, which includes a few academic institutions such as Cambridge, UCL, Lancaster, Sheffield and the Diamond Light Source. There is also industrial collaboration with companies like AGM.
The main goal is to work towards the production of a sodium battery prototype with a standard electrochemical performance in terms of energy density and power density.
Back to Professor Corr
Looking at safer sustainable batteries
The batteries in electric cars and smartphones are flammable
Research is taking place into solid state batteries, replacing flammable electrolytes with safer alternatives that can increase the voltage accessed by the battery.
The advantages of solid electrolytes are: high electrochemical stability; no need for a physical separator; higher, safer voltages.
The challenges include putting the right sides together. They won’t fix together if they are the wrong way round.
Asking two solids to meet and fit together can be a bit of a challenge owing to the difficulty of lithium ions moving from the solid electrode through the solid electrolyte.
A way round the problem is to put some polymer between the two electrodes that would allow the lithium ions to move between the two electrodes.
Using polymers or nice coatings to fine tune the crystal structure.
Matching materials that will work well together nicely and allow lithium ions to move more easily between the electrode and electrolyte
Instead of picking very different materials for the electrode and electrolyte in terms of crystal structure, which makes the lithium pathway difficult to navigate, Sheffield have been coming up with new families of electrolytes where they have doing crystal structure tuning.
Solid state electrolytes
The image above left is an electron microscopy image showing the anode material towards the top. Above right shows the layer coloured blue. It is sitting on top of the solid electrolyte.
The graph in the image above comes from a stability test to check the reactivity of electrolytes with lithium. Researchers would like to use metallic lithium as an anode, but if dendrites form this would be a problem. So far this hasn’t been seen with solid electrolytes.
How do we know what we’ve made?
The research team do all the synthesis, look at the results with electron microscopy and try to understand the morphology. This information helps them when they are trying to incorporate them into a battery
An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a higher resolving power than light microscopes and can reveal the structure of smaller objects. A scanning transmission electron microscope has achieved better than 50 pm resolution in annular dark-field imaging mode and magnifications of up to about 10,000,000× whereas most light microscopes are limited by diffraction to about 200 nm resolution and useful magnifications below 2000×.
Electron microscopes use shaped magnetic fields to form electron optical lens systems that are analogous to the glass lenses of an optical light microscope.
Electron microscopes are used to investigate the ultrastructure of a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, metals, and crystals. Industrially, electron microscopes are often used for quality control and failure analysis. Modern electron microscopes produce electron micrographs using specialized digital cameras and frame grabbers to capture the images.
X-rays are used to try and understand the structure of the material.
X-ray diffraction and electron microscopy are techniques that can be done in university labs.
X-ray diffraction and X-ray absorption spectroscopy
X-ray crystallography (XRC) is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information.
X-ray absorption spectroscopy (XAS) is a widely used technique for determining the local geometric and/or electronic structure of matter. The experiment is usually performed at synchrotron radiation facilities, which provide intense and tunable X-ray beams. Samples can be in the gas phase, solutions, or solids
X-ray diffraction computed tomography
X-ray Diffraction Computed Tomography (DCT) determines the 3D distribution of crystallographic orientations in a solid by detecting and interpreting X-ray diffraction spots and tracing them back to their origin point.
Collecting diffraction data and putting all the information of how these materials are atomically connected together into a computer. It spatially resolves the different materials within a battery.
Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material. A sample to be examined is placed in a beam of thermal or cold neutrons to obtain a diffraction pattern that provides information of the structure of the material. The technique is similar to X-ray diffraction but due to their different scattering properties, neutrons and X-rays provide complementary information: X-Rays are suited for superficial analysis, strong x-rays from synchrotron radiation are suited for shallow depths or thin specimens, while neutrons having high penetration depth are suited for bulk samples.
Neutron diffraction is useful if very light elements need to be investigated
Total scattering methods
The results of combining all the different methods of investigating a material.
Muon spin relaxation spectroscopy
Muon spin spectroscopy is an experimental technique based on the implantation of spin-polarized muons in matter and on the detection of the influence of the atomic, molecular or crystalline surroundings on their spin motion. The motion of the muon spin is due to the magnetic field experienced by the particle and may provide information on its local environment in a very similar way to other magnetic resonance[a] techniques, such as electron spin resonance (ESR or EPR) and, more closely, nuclear magnetic resonance (NMR).
Muon spin relaxation is a very sensitive method of detecting weak internal magnetism, that arises due to ordered magnetic moments, or random fields that are static or fluctuating with time. It is an active probe of ion diffusion in energy storage materials.
If muon spin relaxation spectroscopy is required the material is sent to the Diamond Light Source and the ISIS muon source in Harwell.
Diamond Light Source (or Diamond) is the UK’s national synchrotron light source science facility located at the Harwell Science and Innovation Campus in Oxfordshire. Its purpose is to produce intense beams of light whose special characteristics are useful in many areas of scientific research. In particular it can be used to investigate the structure and properties of a wide range of materials from proteins (to provide information for designing new and better drugs), and engineering components (such as a fan blade from an aero-engine) to conservation of archaeological artefacts (for example Henry VIII’s flagship the Mary Rose.
The ISIS Neutron and Muon Source is a pulsed neutron and muon source, established 1984 at the Rutherford Appleton Laboratory of the Science and Technology Facilities Council, on the Harwell Science and Innovation Campus in Oxfordshire, United Kingdom. It uses the techniques of muon spectroscopy and neutron scattering to probe the structure and dynamics of condensed matter on a microscopic scale ranging from the subatomic to the macromolecular.
Hundreds of experiments are performed every year at the facility by researchers from around the world, in diverse science areas such as physics, chemistry, materials engineering, earth sciences, biology and archaeology.
ISIS Neutron and Muon Source’s second target station.
A tour of ISIS and an interview with Dr Gabriel Perez
Research scientist, ISIS neutron and muon source
ISIS neutron and muon source is a world-class research facility where neutrons and muons are produced to answer some of the most interesting questions in various scientific disciplines. From chemistry, physics and biology to archaeology. Now neutron and muon instruments can be thought of as very powerful microscopes that allow scientists to look into the insides of matter and each different instrument and technique is designed to investigate and understand how atoms are arranged and how they move.
Looking into the inside of newly developed materials is crucial to understand them so that we can continue to improve them, and also use the information to design new materials. This is why neutron and muon facilities such as ISIS play a key role in the hunt for new battery materials.
ISIS is contributing in two ways to the FutureCat’s goal of developing the next generation of lithium-cathode materials. First, it is using neutrons to study and determine the atomic structure of the different materials that are developed by the FutureCat collaborators located across the country.
At the same time ISIS is developing new methods for measuring and analysing those materials so that it can improve researchers’ ability to study complex atomic structures much more effectively.
Now the other way in which ISIS is contributing into the FutureCat project is by using muons to determine how easily lithium ions move within the cathode materials. This is important as the researchers need to ensure that the newly developed materials will allow for fast charging and high-power discharge,
Images of ISIS Neutron and Muon Source experimental hall Target Station 1
Muon instrument stations:
In target station 1, 40 proton pulses are produced every second, 24 hours a day. They are directed towards a large piece of tungsten metal.
The protons are travelling very fast so they collide with the tungsten target very violently and this produces neutrons, about 20 neutrons per proton.
These neutrons are travelling at very high speeds, but they can’t be used like that so they are slowed down by a moderator.
At target station 1 the slowed down neutrons fly off to 17 different instruments, each one specialised for different purposes to study different aspects of matter.
Before the protons collide with the target they first pass through a piece of carbon. This process produces particles called muons which are directed towards five different muon instruments which are specialised for different purposes.
Polaris is a neutron diffractometer optimised for the rapid characterisation of structures, the study of small amounts of materials, the collection of data sets in rapid time and the studies of materials under non-ambient conditions.
Polaris is one of the neutron instruments being used to study the structure of the next generation cathodes that FutureCat is developing.
The sample goes inside the sample chamber and its specific atomic structure scatters the neutrons in different directions.
By studying the scattering patterns the atomic structure of the sample can be understood.
In order to do this the landing points of the neutrons need to be detected.
Schematic diagram below showing the layout of the Polaris beamline following its upgrade. A—direction of incident neutron beam from target station, B—t-zero chopper, C–beam defining adjustable jaws, D—crane (for loading sample environment equipment), E—sample position, F—detector module (1 of 38), G—cable routes to electronics cabin, and H—beam stop.
Above left shows the detector chamber. Above centre and right is the sample chamber
Above left the hand is pointing to where the neutrons enter the chamber. Above right the hand is indicating where the sample, which gets hit by the neutrons, is.
The neutrons are scattered and detected by the detectors shown below.
The detectors are positioned at different angles from the plane where the sample sits as neutrons will arrive from different directions.
The complete array of detectors is necessary to track the direction followed by every neutron.
The above images show the EMU instrument. It is a muon instrument being used to study FutureCat samples.
The hand in the image above is indicating where the sample is placed and the muons get implanted into it after a very short period of time. After about two millionths of a second the muons decay and positrons are emitted.
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1 e (it has a positive charge), a spin of 1/2 (the same as the electron), and has the same mass as an electron.
These positrons are detected and are analysed to understand how lithium ion diffusion occurs within the materials that FutureCat is developing.
Back to Professor Corr for questions and answers
1) We talk about massive improvements in battery power and performance but why does my smartphone still run out of “puff” by mid-afternoon?
It is really down to how you treat the battery in your phone. People tend to put their phone on charge and leave it connected even when it has charged. This is not a good thing.
A battery should not experience extremes. It should not be run down to 0V, but it shouldn’t be kept at maximum either. It puts the device under a lot of pressure. Keeping the charge between 50% and 80% might prolong battery life. New phones use a lot more power than older phones.
Smart charging is a way of keeping the device at a sensible level and is becoming very important for electric vehicles.
2) A petrol car has a lead-acid battery. How do lead-acid batteries and lithium-ion batteries compare?
Early electric vehicles had lead acid batteries. One of them did an 1800-mile journey to New York in 20 days (with stops en-route for charging).
Lead acid batteries are still used for ignition, lights etc. in petrol/diesel cars and they are cost effective, but lithium ion batteries provide a better cycle life and give a better specific capacity. Lead is toxic so there is a movement to phase lead materials out.
Also, with lead acid batteries the charging and discharging has to be just right or the lead can be “eaten” away forming a crystalline phase of lead sulphate.
Normally lead sulphate would dissolve, re-emerge and dissolve etc. but if it isn’t recharged properly then more and more crystalline lead sulphate is permanently produced and this decreases the performance of the battery. Lithium ion batteries do not have this problem.
3) How do issues of heat evolution get addressed? What was the issue with the batteries in some laptops and phones catching fire?
There is a huge amount of work going on in heat management. Dendrite formation is being mitigated. It is hoped that solid electrolytes will help. Reducing the liquid electrolyte will reduce the liklihood of dendrites growing through the battery.
There is still a lot of work to be done on solid state batteries as they could produce high internal resistances. Lithium ions can’t get through. However solid state batteries are the future.
4) Do quasicrystals have a place in battery technology research?
A quasiperiodic crystal, or quasicrystal, is a structure that is ordered but not periodic.
Professor Corr wasn’t sure that they are being used for energy storage although she was aware they’ve been used for hydrogen storage.
There has been some work on superconductivity so there could be some storage applications there.
She wasn’t aware that lithium and sodium have a connection
5) I’ve read that lithium-air batteries could be the next big thing. What is the current stage of development?
It’s exciting because they have a very high theoretical capacity. Quite high energy densities. However, there are challenges to be overcome. Their cyclability needs to be improved and the discovery of new materials to make up catalysts in lithium-air batteries needs to be done before they are commercially viable.
They are an interesting technology with benefits.
6) Is there a use for graphene in batteries?
Yes, there is. Carbon sometimes needs to be added into the cathodes to improve conductivity. Using carbon atoms enhances the battery.
Also looking at the anode side of things. Lots of work on composites in anodes. Using the carbon graphene (single atom thick sheets).
Work is also being done on silicon anodes as they can provide a greater energy density. Interesting to see how carbon interacts with silicon atoms in the anode as silicon has degradation issues.
7) What material industries should we be investing in?
More sustainable technologies
Marriage of technologies
8) One of the electrolytes used in a coil battery is 1M LiTFSI + LiNO3
9) Galvani didn’t make a battery
Volta’s original pile models had some technical flaws, one of them involving the electrolyte leaking and causing short-circuits due to the weight of the discs compressing the brine-soaked cloth.
Another problem with Volta’s batteries was short battery life (an hour’s worth at best), which was caused by two phenomena. The first was that the current produced electrolysed the electrolyte solution, resulting in a film of hydrogen bubbles forming on the copper, which steadily increased the internal resistance of the battery (this effect, called polarization, is counteracted in modern cells by additional measures). The other was a phenomenon called local action, wherein minute short-circuits would form around impurities in the zinc, causing the zinc to degrade.
Modern batteries are safer, give a grater range of voltages and are smaller
Electric cars appear to have the edge in today’s environment, a number of manufacturers are still committed to hydrogen fuel cell cars – meaning that the technology may one day find its place in the motoring world.
Green technology news site CleanTechnica claims that hydrogen fuel cell cars are “several years behind battery electric vehicles in terms of innovation”, which is why they’re so expensive to own and run.
Given enough time and money, hydrogen vehicles may become the more accessible in the future. But electric cars are evolving at a rapid rate, too, and more environmentally-friendly battery options may open up in the future.
For now, though, electric cars appear to be the go-to mode of transport for those looking to do their part in cutting emissions.
11) Quantum mechanics is the theory which describes the interactions of light and matter on the atomic and molecular level
Quantum mechanics is the science of the very-small things. It explains the behaviour of matter and its interactions with energy on the scale of atomic and subatomic particles.
12) Research is needed on renewable energy. However reliable chargeable batteries are needed to store the energy for when the electricity is needed.
In the US it depends on the state whether hybrid is better than an electric car
14) Some sodium-based batteries do contain nickel
An atomic battery, nuclear battery, radioisotope battery or radioisotope generator is a device which uses energy from the decay of a radioactive isotope to generate electricity.
They are long-lived but they will run out. There aren’t many applications for them at the moment.
Muons are very sensitive probes of magnetic systems, often detecting effects that are too weak to be seen by other methods.
Muons do not rely on internal nuclear spins and do not require any radio-frequency technique to align the probing spins.
17) Photosynthesis is involved in producing biofuels and burning biofuels produces electricity, which could be stored in the batteries.
18) One way to reduce the cost of research and development is to optimize the design variables of existing electrode materials, such as porosity and thickness, for enhanced power and capacity
A betavoltaic device (betavoltaic cell or betavoltaic battery) is a type of nuclear battery which generates electric current from beta particles (electrons) emitted from a radioactive source, using semiconductor junctions. A common source used is the hydrogen isotope tritium. Unlike most nuclear power sources which use nuclear radiation to generate heat which then is used to generate electricity, betavoltaic devices use a non-thermal conversion process, converting the electron-hole pairs produced by the ionization trail of beta particles traversing a semiconductor.
Betavoltaic power sources (and the related technology of alphavoltaic power sources) are particularly well-suited to low-power electrical applications where long life of the energy source is needed, such as implantable medical devices or military and space applications
The primary use for betavoltaics is for remote and long-term use, such as spacecraft requiring electrical power for a decade or two. Recent progress has prompted some to suggest using betavoltaics to trickle-charge conventional batteries in consumer devices, such as cell phones and laptop computers. As early as 1973, betavoltaics were suggested for use in long-term medical devices such as pacemakers.
As radioactive material emits, it slowly decreases in activity (refer to half-life). Thus, over time a betavoltaic device will provide less power. For practical devices, this decrease occurs over a period of many years. For tritium devices, the half-life is 12.32 years. In device design, one must account for what battery characteristics are required at end-of-life, and ensure that the beginning-of-life properties take into account the desired usable lifetime.
Liability connected with environmental laws and human exposure to tritium and its beta decay must also be taken into consideration in risk assessment and product development. Naturally, this increases both time-to-market and the already high cost associated with tritium. A 2007 report by the UK government’s Health Protection Agency Advisory Group on Ionizing Radiation declared the health risks of tritium exposure to be double those previously set by the International Commission on Radiological Protection located in Sweden.
Electrical power is supplied by three MHW-RTG radioisotope thermoelectric generators (RTGs). They are powered by plutonium-238 (distinct from the Pu-239 isotope used in nuclear weapons) and provided approximately 470 W at 30 volts DC when the spacecraft was launched. Plutonium-238 decays with a half-life of 87.74 years, so RTGs using Pu-238 will lose a factor of 1−0.5(1/87.74) = 0.79% of their power output per year.
In 2011, 34 years after launch, such an RTG would inherently produce 470 W × 2−(34/87.74) ≈ 359 W, about 76% of its initial power. Additionally, the thermocouples that convert heat into electricity also degrade, reducing available power below this calculated level.
By 7 October 2011 the power generated by Voyager 1 and Voyager 2 had dropped to 267.9 W and 269.2 W respectively, about 57% of the power at launch. The level of power output was better than pre-launch predictions based on a conservative thermocouple degradation model. As the electrical power decreases, spacecraft loads must be turned off, eliminating some capabilities. There may be insufficient power for communications by 2032
Batteries offer a superior energy density and possess a higher breakdown voltage, while supercapacitors are lighter, have more robust operating limits, possess a longer life expectancy, and have an unparalleled power density.
Recently, a ceramic textile was developed that showed promise in a Li-S solid state battery. This textile facilitated ion transmission while also handling sulfur loading, although it did not reach the projected energy density.
Ceramics can be brittle. But the dense middle layer adds strength. It also makes the battery safer by blocking dendrites, which are tiny needles that can grow when lithium ions deposit on the anode unevenly, piercing the thin plastic separators in today’s cells and causing a hazardous short circuit. And the porous, aluminium oxide-coated layers allow lithium ions to move quickly into the electrolyte.
24) We are starting to mine landfill sites.
They don’t hold as much energy as a battery, but can endure many charge and discharge cycles.
They have a lower inner resistance, so they can output a great current.
Today’s lithium-ion batteries tend to use cathodes (one of the two electrodes in a battery) made of a transition metal oxide but batteries with cathodes made of sulfur are considered a promising alternative to reduce weight. However, sulfur tends to require a lot of extra materials, including an excess of electrolyte and carbon.
The mine, along with a new North American-based cathode manufacturing facility, would be two new additions to Tesla’s growing lineup of factories and operations.
Uses large batteries which would allow the plant to restart even in the event of a complete shutdown of the national grid.
Once running, at full flow, the station can provide power for up to six hours before running out of water. So, it isn’t a permanent renewable energy resource
At the end of 2019 the GB battery storage capacity was 0.88GWh. The forecasts suggest that it could be as high as 2.30GWh in 2025.
Organofluorine based electrolytes wouldn’t be flammable, but unless they could be cleverly recycled, they would be an environmental hazard.
I would also like to thank Sophie Noble as I have used some of her illustrations
Professor Corr videos
Faraday Institution videos