Tunable Heterogeneous FeCo Alloy-Mo_0.82N Bifunctional Electrocatalysts for Temperature-Adapted Zn-Air Batteries

The practical applications of temperature-tolerant Zn-air batteries (ZABs) rely on highly active and stable bifunctional catalysts that accelerate cathodic oxygen reduction (ORR) and oxygen evolution (OER) reactions. Herein, we successfully integrated fascinating transition metal nitrides and FeCo alloys through a simple coordination assembly and pyrolysis process. Importantly, the alloy-to-nitride ratio in the heterogeneous catalyst can be carefully regulated through the subsequent etching process. Moreover, the composition-dependent ORR/OER performance of the FeCo-Mo_0.82N catalysts was revealed. Aqueous ZABs using the optimized FeCo-Mo_0.82N-60 as a cathode exhibit a high peak power density of 149.7 mW cm^-2 and an impressive stability of 600 h with a low charge-discharge voltage gap decay rate of 0.025 mV h^-1, which exceeds those of most of recent reports. Furthermore, the FeCo-Mo_0.82N-60-based flexible ZABs display a small specific capacity degradation (3%) from 40 to -10 °C, demonstrating excellent temperature tolerance.