Engineering Amorphous/Crystalline Structure of Manganese Oxide for Superior Oxygen Catalytic Performance in Rechargeable Zinc-Air Batteries.

Although amorphous materials are popular in oxygen electrocatalysis, their performance requires further improvement to meet the need for rechargeable zinc-air batteries. In this work, an amorphous/crystalline layered manganese oxide (ACMO) was designed, and its unique amorphous/crystalline homogeneous structure activated its oxygen reduction activity with a positive half-wave potential of 0.81 V and oxygen evolution activity with a moderate overpotential of 407 mV at 10 mA cm -2 . Moreover, the amorphous/crystalline structure endowed ACMO with excellent stability. While employed as the air-electrode material for rechargeable zinc-air batteries, ACMO overcame the poor cycling stability of manganese oxide and cycled stably for 1000 cycles (≈17 days) at 10 mA cm -2 . Besides, it delivered a high power density of 159.7 mW cm -2 and a narrow voltage gap of 0.66 V. This work gives an insight into designing oxide materials with amorphous/crystalline structure and feasible guidance for harmonizing electrochemical activity and stability.