NiCo alloy-anchored self-supporting carbon foam as a bifunctional oxygen electrode for rechargeable and flexible Zn–air batteries

Abstract

The design and fabrication of flexible, porous, conductive electrodes with customizable functions become the prime challenge in the development of new-generation wearable electronics, especially for rechargeable batteries. Here, the NiCo bialloy particulate catalyst-loaded self-supporting carbon foam framework (NiCo@SCF) as a flexible electrode has been fabricated through one facile adsorption-pyrolysis method using a commercial melamine foam. Compared with the electrode with Pt/C and Ir/C benchmark catalysts, the NiCo@SCF electrode exhibited superior bifunctional electrocatalytic performance in alkaline media with a half-wave potential of 0.906 V for oxygen reduction reaction, an overpotential of 286 mV at j = 10 mA cm⁻² for oxygen evolution reaction, and stable bifunctional performance with a small degradation after 20,000 voltammetric cycles. The as-assembled aqueous zinc–air battery (ZAB) with NiCo@SCF as a self-supporting air cathode demonstrated a high peak power density of 178.6 mW cm⁻² at a current density of 10 mA cm⁻² and a stable voltage gap of 0.94 V over a 540 h charge−discharge operation. Remarkably, the as-assembled flexible solid-state ZAB with self-supporting NiCo@SCF as the air cathode presented an engaging peak power density of 80.1 mW cm⁻² and excellent durability of 95 h undisrupted operation, showing promise for the design of wearable ZAB. The demonstrated electrode fabrication approach exemplifies a facile, large-scale avenue toward functional electrodes, potentially extendable to other wearable electronics for broader applications.