Polyanionic compounds are of great interest for energy storage applications because they are considerably safer than oxides since they do not release oxygen on decomposition, which can exacerbate thermal runaway when cells fail. While a large body of work has been dedicated to identifying and optimizing the electrochemical performance of these phases, a fundamental understanding of the mechanism for Li-ion transport in these materials is lacking. Unlike oxides, like LiCoO2 or LiMn2O4, which effectively exhibit isotropic changes to the oxygen sublattice, polyanionic electrodes respond to changes in Li concentration through cooperative rotations of subunits with rigid bond lengths.This talk will examine the way that different polyanionic groups rotate or distort in order to accommodate the local strain of ions moving through the lattice and how that affects the rate of ionic diffusion. In this context, recent results from our work to develop new transition metal silicates as well as fast Li-ion conducting garnets will be discussed.

Influence of lattice flexibility on ionic diffusion in materials for energy storage

251st National Meeting (2016)

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