Under the skin: How EV battery researchers are chasing material gains
Success would mean greater capacity than we have today but overcoming a lack of efficiency and poor cycle life have proved difficult to overcome beyond double figures. That said, scientists around the world are still on the case and, earlier this year, researchers at Japan’s National Institute for Materials Science claimed to have developed a lithium air battery with an energy density of 500Wh per kilogram, roughly twice that of the best lithium ion batteries.
Scientists at Illinois Institute of Technology said last year that they have succeeded in overcoming the problem, having achieved 1200 charge and discharge cycles in a prototype battery. Reduced cycle life is due to the other elements in air, such as carbon, nitrogen and water, which also react with lithium and produce a contaminating layer that prevents oxygen reaching the positive electrode and using up lithium.
Other technologies are gathering pace, too. Battery startup company Theion, whose CEO Ulrich Ehmes is experienced in industrialising battery production, has developed a lithium sulphur positive electrode that, it claims, can triple the range given by conventional lithium ion cells. Sulphur is an abundant element and in this case replaces nickel and cobalt.
Theion claims its sulphur-based technology is 99% cheaper to source and making battery cells using it consumes 99% less energy. The company says 16 patents are pending on processes to make the cathodes for what it calls its ‘Crystal Battery’, based on the fact that sulphur exists naturally as a crystal. Theion will build and supply batteries for testing by aerospace customers this year. Automotive use is expected for 2024 and gigafactory-scale production by 2025.