Highly Durable Oxygen Electrode for Rechargeable Zinc-Air Batteries - (PPT)

摘要

Energy storage system has attracted much attention due to the need for EV propulsion and stabilizing power grids with renewable energy integrations. Metal air battery technologies provide high theoretical energy capacities, being capable of fulfilling multiple needs for next generation mobile/stationary energy storage system. Moreover, most of them are also environmentally benign, inexpensive and naturally abundant, such as Al, Zn, and Fe-air batteries. However, the main issue associated with commercialization of such batteries is the development of air cathodes possessing both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) efficiently. In the present work, the bifunctional air electrode composed of alpha phase of manganese oxides, as ORR catalysts, grown on the surface of stainless steel mesh catalyzing OER, was fabricated via electro-deposition method. This as-synthesized oxygen electrode was used directly for zinc-air battery assembly without the need of polymer binders mixing for coating on a desired gas diffusion electrode such as carbon papers. Commonly used binders have low conductivity and suffer from detaching when immersion in alkaline solutions, leading to battery failure. Herein, the zinc-air battery was comprised of as-synthesized air cathode, 6M KOH and zinc foil anode. The battery was operated at the current density of 10 mA/cm~2 and its charge/discharge potential was 1.95V/1.15V, respectively. Most importantly, it showed stable performance with >80% coulombic efficiency over 1000 recharge cycles (～328 hours). Future works will focus on voltage efficiency improvement and detailed working mechanism study of air electrodes.