The phase-change evolution from surface to bulk of MnO anodes upon cycling.

Transition-metal oxides with low valence states are promising candidates as anodes for advanced rechargeable Li-ion batteries. Surprisingly, the capacities of such anode materials initially decrease and then increase after long-term cycling. Herein, MnO is selected as a representative material to study the structure-function relationship and elucidate the above-mentioned phenomena during long-term cycling.