Crystal Phase-Controlled Modulation of Binary Transition Metal Oxides for Highly Reversible Li–O2 Batteries

Reducing charge–discharge overpotential of transition metal oxide catalysts can eventually enhance the cell efficiency and cycle life of Li–O 2 batteries. Here, we propose that crystal phase engineering of transition metal oxides could be an effective way to achieve the above purpose. We establish controllable crystal phase modulation of the binary Mn x Co 1– x O by adopting a cation regulation strategy. Systematic studies reveal an unprecedented relevancy between charge overpotential and crystal phase of Mn x Co 1– x O catalysts, whereas a dramatically reduced charge overpotential (0.48 V) via a rational optimization of Mn/Co molar ratio = 8/2 is achieved. Further computational studies indicate that the different morphologies of Li 2 O 2 should be related to different electronic conductivity and binding of Li 2 O 2 on crystal facets of Mn x Co 1– x O catalysts, finally leading to different charge overpotential. We anticipate that this specific crystal phase engineering would offer good technical support for developing high-performance transition metal oxide catalysts for advanced Li–O 2 batteries.