摘要
Development of cost-effective highly efficient and robust bifunctional oxygen electrocatalysts is critical for practical applications of zinc air batteries (ZABs). Multi-metallic alloys, possessing versatile active sites, are promising candidates to tackle multi-step oxygen reactions involved in ZABs. Here, rationally designed singlephase Co-based quaternary alloy nanoparticles anchored on N-doped carbon nanosheets, CoCuFeNi@N-C, are developed as bifunctional oxygen electrocatalysts for high performance aqueous and flexible ZABs. The catalyst is grown in-situ onto a porous conductive substrate to fabricate 3-D composite binder-free air positive electrodes, allowing fast electron and mass transport to support accelerated oxygen redox kinetics. The CoCuFeNi@N-C based aqueous ZAB delivers an ultralow voltage gap of 1.644 V at 400 mA cm-2, an ultrahigh discharge peak power density of 301 mW cm-2 at 442 mA cm-2, and remarkable cycling stability of 3100 cycles (1033 h) at 5 mA cm-2 and 1650 cycles (550 h) at 10 mA cm-2, largely outperforming the Pt/C + RuO2 based one. The CoCuFeNi@N-C and PVA based flexible ZAB delivers an excellent discharge peak power density of 92.2 mW cm-2 at 132 mA cm-2 and operates stably under bending angles up to 180 degrees without performance decay. Rational alloying design for multi-metallic materials proves to be an effective approach for development of advanced bifunctional oxygen electrocatalysts for high performance ZABs.