The future is electric – at least for cars. The only real question is when that future will begin. There are two million fully electric cars on the world’s roads. The latest forecast from Deloitte predicts this number will rise to 12 million by 2025 and to 21 million by 2030.
But the numbers will depend on the development of a new generation of batteries that don’t cost the earth and allow electric cars to travel as far and efficiently as their hydrocarbon-fuelled cousins.
This is no easy task. Battery chemistry is fiendishly complex and the engineering challenge of safely storing so much energy in such a small space is not for the faint-hearted. And yet scientists at one of the world’s leading chemicals and sustainable technologies companies say they’re creating the most advanced battery materials yet.
The company in question is Johnson Matthey, a global leader in science that makes the world cleaner and healthier. It produces the catalytic converters found in a third of all cars worldwide, it manufactures the components at the heart of fuel cells and it has increased the sustainability of many industrial processes, such as the refining of precious metals, as well as using its science to enable life-enhancing pharmaceuticals. Now the task of applying its science to build better batteries is one of its most significant areas of development.
One of the keys to a battery’s capacity and performance is the design of the cathode electrode, which contains lithium ions. When the battery is used, positively charged lithium ions flow into the cathode inside the cell. At the same time, electrons flow around the external circuit, also into the cathode.
When the battery is charged, these processes occur in the opposite direction. So the cathode must also be able to release the lithium ions and electrons without compromising its physical structure. And it must be able to repeat this charging cycle many times over.
So the cathode’s ability to release and accept lithium ions and electrons is a key factor in the battery’s capacity and performance. “The amount of lithium you’re able to shuttle back and forth is the battery’s capacity,” says Joanna Clark, Head of Product Development for battery materials at Johnson Matthey. “The more lithium the cathode is able to release without the structure becoming unstable, the more capacity and energy you have, and the more miles in your tank.” How quickly you can move lithium in and out of the structure is also important – this is the power performance, and in electric vehicles it relates to acceleration and how long it takes to recharge the battery.
Johnson Matthey has been developing and testing better battery materials. Recently, its researchers came up with a novel combination of cathode materials that should significantly improve the range and acceleration of electric cars, while also making them quicker to recharge. The breakthrough could help bring electric cars into the mainstream, by lessoning the need for car driver behaviour changes, marking an important turning point for the industry.
To keep the arrangement stable, cathode electrodes are typically layered structures with lithium interspersed with other metal oxides. “Think about the cathode structure as a big pile of Jenga bricks,” explains Clark. “Every time you take a lithium ion out, it’s like taking one brick out of the tower. You can only take so many out before the structure collapses.”
To reach the energies required to combat range anxiety and encourage the mass-adoption of electric vehicles, battery manufacturers are moving to high-nickel chemistries. Nickel provides energy, but it comes at the cost of stability – so it gives you the miles in your tank but limits the useful life of the battery.
The key to harnessing this energy is taming the nickel. A traditional choice of stabilising material in lithium-ion cathodes is cobalt. However, cobalt is expensive, which makes its use in large electric car batteries uneconomic.
Furthermore, ethical sources are in short supply. So to keep everything stable, it’s necessary to add small amounts of
cheaper metals, such as manganese or aluminium – but these do not bring some benefits afforded by cobalt, so there are trade-offs.
The trick that Johnson Matthey’s scientists have perfected is to find just the right combination and arrangement of metals. Their work involves experimenting with and simulating the physical and chemical properties of various formulations.
The result is a portfolio of new ultra high energy cathode materials, known as eLNO, which have high levels of nickel but low levels of cobalt. The nickel-rich mix ensures a high-energy product but the other metals ensure the stability and safety of the design.
This combination maximises two crucial aspects of a battery’s design–its energy density (the amount you get in a certain volume or mass) and its cycle life (how many times you can discharge and recharge the battery without significant loss of capacity). In engineering terms, it is the result of many incremental steps that together make a significant difference to the efficiency and economics of large-scale battery manufacturing.
Finding the right combination is only one part of the challenge. “You can only get so far looking at materials composition alone,” says Clark. “You also have to process it into an electrode and get the best out of it in that way. We have an understanding of that. You cannot design the best material unless you understand how it performs as an electrode and in a battery cell.”
The trick, she adds, was to find a way to use the smallest possible amount of cobalt to stabilise the highest possible amount of nickel, essentially by putting all the component metals in the right places in the cathode structure. “This was engineering at the atomic level.”
All this is possible because of Johnson Matthey’s decades-long expertise in catalysis and materials science. The company has a team with diverse scientific and engineering backgrounds who played a major part in the achievement.
Andy Walker, Technical Marketing Director at Johnson Matthey, adds: “The class-leading energy density of our eLNO technology enables a significant increase in the distance that electric vehicles can drive before needing to recharge, which will increase customer pull for these vehicles, accelerating the electrification of the automobile market.”
The future of the electric car market, and the speed with which consumers switch from petrol and diesel vehicles in favour of the cleaner alternative, will depend on several factors, including cost, safety, driving performance, the time it takes to ‘refuel’ and how far you can travel on a full tank.
Most batteries currently on the market tick one of these boxes, but the batteries of the future will have to tick them all. With its new eLNO technology, Johnson Matthey says it has taken a big step towards that goal.
Much more needs to happen: electric vehicle infrastructure such as charging points is still woefully inadequate, for example. But as Clark points out, with the right batteries, “the potential is limitless”.
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Article originally published by New Scientist