Boosting bifunctional catalytic activity of perovskite nanoparticles for rechargeable Zn-air batteries

Abstract

Superior oxygen electrocatalysts take on a critical significance in the exploitation of Zn-air batteries. In this study, a bifunctional oxygen electrocatalyst based on La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF) was designed and synthesized using the hydrothermal method combined with chemical solution deposition. LSCF nanocubes provided more surface oxygen vacancies and catalytically active sites for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline solutions. In comparison, silver nanoparticles and graphene provided a fast pathway for electron transfer and mass diffusion since the electron transfer from Ag to LSCF can accelerate the adsorption of O2 and increase the length of O–O bond. The integration of Ag, LSCF and graphene leads to the formation of an efficient nanointerface and good bifunctional electrocatalytic performance with a charge and discharge potential gap of 0.71 V. The flexible Zn-air battery with Ag/LSCF@graphene as the cathodic catalyst exhibited a high power density of 99.62 mW cm−2, a large specific capacity of 583.4 mAh g−1Zn, as well as superior charge/discharge stability even at different bending angles. This study may lay a basis for the exploitation of precious metal-free electrocatalysts and the application of perovskite oxides in energy storage and conversion.