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

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.