TiC supported amorphous MnOx as highly efficient bifunctional electrocatalyst for corrosion resistant oxygen electrode of Zn-air batteries

Zn-air batteries (ZABs) represent promising candidates for the next generation energy conversion and storage systems based on their superior features to those of lithium-ion batteries, including high theoretical energy density , low cost, and high safety. However, their further development and application is severely lagged due to the lack of high efficient and durable bifunctional oxygen electrocatalysts . The widely applied carbon-based catalysts are thermodynamically instable during battery charging. Herein, TiC supported amorphous MnO x (a-MnO x /TiC) is reported for the first time as electrocatalyst for the corrosion resistant oxygen electrodes of ZABs. A-MnO x /TiC delivers a remarkable activity and stability toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with a high half-wave potential (0.8 V) for ORR and a low potential (1.56 V) at 10 mA cm −2 for OER, which far outperforms the state of the art ORR catalyst (Pt/C) and OER catalyst (IrO 2 ), as well as the Pt/C-IrO 2 and a-MnO x /C bifunctional catalysts . The excellent bifunctional activity of a-MnO x /TiC can be attributed to the efficient synergistic effect between the active amorphous MnO x catalyst and the highly conductive and stable TiC support. More impressively, a-MnO x /TiC demonstrates an outstanding electrochemical stability in strong alkaline electrolyte under OER condition in contrast to the readily oxidized carbon-based a-MnO x /C catalysts. ZAB with a-MnO x /TiC delivers a greater discharge performance with a peak power density of 217.1 mW cm −2 than that of Pt/C-based ZAB, and a surpassing discharge and charge cycling performance and stability to ZABs with Pt/C-IrO 2 and a-MnO x /C. Furthermore, a-MnO x /TiC can be applied for solid-state ZABs which exhibit excellent mechanical flexibility and cycle stability under their flat and bent states. The a-MnO x /TiC bifunctional electrocatalyst with extraordinarily high activity and electrochemical stability provides a promising approach for exploring corrosion resistant electrocatalysts for Zn-air batteries with high efficiency and long-term cycling stability.