Durable bifunctional electrocatalyst for cathode of zinc-air battery: surface pre-reconstruction of La0.7Sr0.3MnO3 perovskite by iron ions

Abstract

The utilization of manganese-based perovskite in rechargeable Zn-air batteries encounters challenges related to low catalytic activity and inadequate stability. In this study, we have employed a surface pre-reconstruction technique to produce La0.7Sr0.3MnO3 nanoparticles adorned with iron ions (LSM/Fe-1.5). The optimized LSM/Fe-1.5 catalyst demonstrates an increase in ORR and OER intrinsic activities by 1.8 and 4.9 times, respectively, exhibiting ORR/OER bifunctional activity comparable to that of commercial Pt/C and RuO2. The Zn-air battery employing the LSM/Fe-1.5 catalyst exhibits a charge-discharge voltage difference of 0.89 V after 1500 cycles (500 h). The improved activity of ORR can be attributed to the selective dissolution of A-site cations, optimization of B-site electronic structure and oxygen vacancy concentration. The enhanced OER activity can be ascribed to the augmentation of adsorption energy of iron ions on the surface of perovskite, along with the synergistic influence of iron ions and surface oxygen vacancies. This study not only presents an effective approach for developing efficient and durable bifunctional catalysts for broader application in Zn-air batteries, but also broadens the influence of iron ions in the OER process to include manganese-based perovskite oxide.