Mechanisms of sodiation in anatase TiO in terms of equilibrium thermodynamics and kinetics.

Anatase TiO is a promising anode material for sodium-ion batteries (SIBs). However, its sodium storage mechanisms in terms of crystal structure transformation during sodiation/de-sodiation processes are far from clear. Here, by analyzing the redox thermodynamics and kinetics under near-equilibrium states, we observe, for the first time, that upon Na-ion uptake, the anatase TiO undergoes a phase transition and then an irreversible crystal structure disintegration.