Synergistic Bimetallic CoCu-Codecorated Carbon Nanosheet Arrays as Integrated Bifunctional Cathodes for High-Performance Rechargeable/Flexible Zinc-Air Batteries.

ABSTRACT

The unremitting exploration of well-architectured and high-efficiency oxygen electrocatalysts is promising to speed up the surface-mediated oxygen reduction/evolution reaction (ORR/OER) kinetics of rechargeable zinc-air batteries (ZABs). Herein, bimetallic CoCu-codecorated carbon nanosheet arrays (CoCu/N-CNS) are proposed as self-supported bifunctional oxygen catalysts. The integrated catalysts are in situ constructed via a simple sacrificial-templated strategy, imparting CoCu/N-CNS with 3D interconnected conductive pathways, abundant mesopores for electrolyte penetration and ion diffusion, as well as Cu-synergized Co-Nx /O reactive sites for improved catalytic activities. By incorporating a moderate amount of Cu into CoCu/N-CNS, the bifunctional activities can be further increased due to synergistic oxygen electrocatalysis. Consequently, the optimized CoCu/N-CNS realizes a low overall overpotential of 0.64 V for OER and ORR and leads to high-performance liquid ZABs with high gravimetric energy (879.7 Wh kg-1 ), high peak power density (104.3 mW cm-2 ), and remarkable cyclic stability upon 400 h/1000 cycles at 10 mA cm-2 . More impressively, all-solid-state flexible ZABs assembled with the CoCu/N-CNS cathode exhibit superior rate performance and exceptional mechanical flexibility under arbitrary bending conditions. This CoCu/N-CNS monolith holds significant potential in advancing cation-modulated multimetallic electrocatalysts and multifunctional nanocatalysts.