Janus-Typed Integrated Bifunctional Air Electrode with MnO_x-NiFe LDH/Ni Foam for Rechargeable Zinc-Air Batteries

Rechargeable zinc-air batteries (ZABs) are considered as some of the most promising electrochemical storage systems owing to their high energy density and low-cost. However, the low energy efficiency and poor cycle-life impede the further development of rechargeable ZABs. It is desirable to improve the performance of ZABs by developing highly efficient, long-life time bifunctional air electrodes. We propose a Janus-typed integrated bifunctional air electrode, which consists of MnO x and NiFe layered double hydroxide (LDH) by means of electrodeposition on Ni foam. The Janus-typed integrated bifunctional air electrode can avoid positive oxidation of MnO x owing to the spatial separation of the oxygen reduction and evolution reactions (ORR and OER). Moreover, based on the unique structure, the resulting air electrode exhibits better catalytic activity due to the combination of the unique advantages of MnO x and FeNi LDH, and the enhancement of active species transportation. This Janus-typed air electrode for rechargeable ZAB achieved an energy efficiency of 65.7% at 10 mA cm −2 , excellent stability over 110 h, and peak power density of 120 mW cm −2 . The Janus structure for the bifunctional electrode provides a valuable approach to develop high-performance rechargeable ZABs.