Researchers take one step closer to super-fast-charging batteries

Diagram showing the atomic scale processes that occur within Wadsley–Roth phases during operation of a battery

Dr Andrew Morris’s research group from the School of Metallurgy and Materials at the University of Birmingham have explained, in an article in the Journal of the American Chemical Society, the behaviour of a new class of super-fast charging battery materials. The research was carried out in collaboration with scientists from the University of Cambridge.

A key technological challenge is to recharge an electric car in the time it takes to fill a petrol car’s tank. The lithium-ion battery has been at the forefront of vehicle electrification but further improvements are desired. To achieve a fast-charging, long-distance electric car we must discover new electrode materials which can hold more lithium and both absorb and release it quickly.

Many new materials have been proposed, but the vast majority suffer from cracking and disintegration as lithium is added and removed or they cannot be easily produced at the scale required for electric vehicles. Safety and sustainability are also critical requirements for new battery materials.

Last year, in research published in the journal Nature, it was shown experimentally that a family of materials known as Wadsley–Roth crystallographic shear phases exhibit a useful effect. At the University of Cambridge, Prof Clare Grey and Dr Kent Griffith found these materials behave very strangely as they are being filled with lithium. During filling they actually shrink in two of their three-dimensions, limiting their volume expansion and hence the damage on fast charging. This increases the lifetime of the batteries and improves the safety properties.

Can Koçer, a PhD student in Morris’ group, used the Midland’s supercomputer to model the atomic scale processes that occur within Wadsley–Roth phases during operation of a battery. He found that as lithium is added, distortions within the atomic structure of these materials are removed, which leads to the limited volume expansion. By studying fundamental mechanisms in energy storage materials, the Morris group’s work can help experimentalists improve materials performance even further. “Computational modelling is often the most direct way to look inside a material and see what is going on”, says Dr Morris. “This is especially true in materials with complex structures, like the Wadsley—Roth phases.”

By combining world-leading experiment with supercomputer modelling, we are one step closer to super-fast-charging batteries.