Manganese Oxide Catalyst Grown on Carbon Paper as an Air Cathode for High-Performance Rechargeable Zinc-Air Batteries

Manganese oxide is grown directly on carbon paper through a simple immersion process, and used as a catalyst-modified air cathode for rechargeable zinc-air batteries. The manganese oxide is distributed evenly within the porous carbon paper, which promotes a rapid three-phase reaction and high utilization of the active materials. Zinc-air batteries with the manganese oxide catalyst directly grown on the carbon paper exhibit improved performance compared with zinc-air batteries fabricated by using manganese oxide powder catalyst coated on carbon paper. The directly grown catalyst reduces the contact resistance and enhances the discharge/charge profile of the zinc-air batteries. Zinc-air batteries with the directly grown catalyst show a discharge voltage of 1.2 V at a current density of 15 mA cm^-2 and deliver a power density as high as 108 mW cm^-2 at an applied current of 168 mA cm^-2 . Furthermore, good cycling stability for up to 500 cycles is achievable during continuous discharge-charge tests without the need to replace the zinc anode or replenish the electrolyte; this outperforms most currently available bifunctional catalysts for rechargeable zinc-air batteries. This study illustrates a promising platform to enhance the cycle life of rechargeable metal-air batteries.