Hydrothermally Grown Dual‐Phase Heterogeneous Electrocatalysts for Highly Efficient Rechargeable Metal‐Air Batteries with Long‐Term Stability

Metal‐air batteries as alternatives to the existing lithium‐ion battery are becoming increasingly attractive sources of power due to their high energy‐cost competitiveness and inherent safety; however, their low oxygen evolution and reduction reaction (OER/ORR) performance and poor operational stability must be overcome prior to commercialization. Herein, it is demonstrated that a novel class of hydrothermally grown dual‐phase heterogeneous electrocatalysts, in which silver‐manganese (AgMn) heterometal nanoparticles are anchored on top of 2D nanosheet‐like nickel vanadium oxide (NiV2O6), allows an enlarged surface area and efficient charge transfer/redistribution, resulting in a bifunctional OER/ORR superior to those of conventional Pt/C or RuO2. The dual‐phase NiV2O6/AgMn catalysts on the air cathode of a zinc‐air battery lead to a stable discharge–charge voltage gap of 0.83 V at 50 mA cm−2, with a specific capacity of 660 mAh g−1 and life cycle stabilities of more than 146 h at 10 mA cm−2 and 11 h at 50 mA cm−2. The proposed new class of dual‐phase NiV2O6/AgMn catalysts are successfully applied as pouch‐type zinc‐air batteries with long‐term stability over 33.9 h at 10 mA cm−2. The noble dual‐phase heterogeneous electrocatalysts derived by sequential hydrothermal reactions enable an increased surface area and efficient charge transfer/redistribution, resulting in a superior bifunctional oxygen evolution and reduction reaction (OER/ORR). These findings indicate that dual‐phase heterogeneous electrocatalysts may provide a unique opportunity to improve the performance of rechargeable metal‐air battery applications.