Preparation And Performance Study Of Corrosion-resistant Oxygen Electrode For Rechargeable Zinc-air Battery

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,Ti C supported amorphous MnO_x?a-MnO_x/Ti C?is reported for the first time as electrocatalyst for the corrosion resistant oxygen electrodes of ZABs.a-MnO_x/Ti C 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 m A cm^-2for OER,which far outperforms the state of the art ORR catalyst?Pt/C?and OER catalyst?Ir O₂?,as well as the Pt/C-Ir O₂and a-MnO_x/C bifunctional catalysts.The excellent bifunctional activity of a-MnO_x/Ti C can be attributed to the efficient synergistic effect between the active amorphous MnO_xcatalyst and the highly conductive and stable Ti C support.More impressively,a-MnO_x/Ti C 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/Ti C delivers a greater discharge performance with a peak power density of 217.1 m W cm^-2than that of Pt/C-based ZAB,and a surpassing discharge and charge cycling performance and stability to ZABs with Pt/C-Ir O₂and a-MnO_x/C.Furthermore,a-MnO_x/Ti C can be applied for solid-state ZABs which exhibit excellent mechanical flexibility and cycle stability under their flat and bent states.Subsequently,an efficient bifunctional oxygen electrocatalyst based on?-MnO₂NWs coated by stable and highly conductive Ti C nanoparticles?NPs?was further prepared and applied for the first time.Ti C-coated?-MnO₂NWs?Ti C/?-MnO₂NW?delivers a remarkable bifunctional activity with a half-wave potential of 0.78 V for ORR and a low potential of 1.64 V at 10 m A cm^-2for OER,far exceeding the pristine?-MnO₂NWs.The ZAB with Ti C/?-MnO₂NW achieves a higher peak power density of 161 m W cm^-2and a better cycle performance.The a-MnO_x/Ti C and Ti C/?-MnO₂NW bifunctional electrocatalysts with extraordinarily high activity and electrochemical stability provide a promising approach for exploring corrosion resistant electrocatalysts for Zn-air batteries with high efficiency and long-term cycling stability.