Jahn–Teller Assisted Na Diffusion for High Performance Na Ion Batteries

Na energy storage technology is strategically attractive for large scale applications such as grid energy storage. Here, we show that there is a clear relation between the Jahn-Teller activity of a transition metal ion at the end of charge and the mobility of Na in a cathode material. This is particularly important as mobility at the end of charge limits the capacity of current materials. Hence, by using this classical piece of physics in the battery world, it is possible to create higher capacity Na-cathode materials. Even more exciting is that the ideal element to impart this effect on cathodes is Fe, which is the least expensive of the transition metal oxides and can therefore enable low cost cathode materials.