Novel air-rechargeable aqueous Zn-based batteries with N-doped hierarchical-porous carbon as the capacitor-type cathode

Abstract

The existing air-rechargeable aqueous Zn-based batteries (AZBBs) possess an ultraslow air-charging speed, seriously restricting their further development. Herein, we innovatively constructed the capacitor-type air-rechargeable AZBBs based on KOH-activated and nitrogen-doped hierarchical-porous carbon (K-NHPC) cathode, completely breaking away from the customary thinking mode of electrode optimization and fundamentally breaking through the limitation of air-charging speed. As a result, K-NHPC cathode can complete an air self-charging process in a very short time of only 40 minutes and its average hourly air-charging capacity is high up to 248.9 mAh g⁻¹h⁻¹, benefiting from its ultrafast processes of charge desorption and oxygen reduction reaction (ORR). Compared with that of the existing air-rechargeable AZBBs, the air-charging speed of our capacitor-type air-rechargeable AZBBs has been significantly increased by an order of magnitude. The charge-storage and air-charging mechanisms are untangled in detail through a series of in-situ/ex-situ experimental characterizations and theoretical calculations. Especially, we first disclose that the redox reaction and charge redistribution can cause the air self-charging and the resultant potential rise of NHPC cathode. Furthermore, the multi-scenario application prospects (a wide temperature range, flexible devices and pouch cells) of our capacitor-type air-rechargeable AZBBs have been verified. This work blazes a new trail of AZBBs with an ultrafast air self-charging speed, which is of great fundamental and original significance.