Promoting Reaction Kinetics of the Air Cathode for Neutral Zinc-Air Batteries by the Photothermal Effect

Rechargeable neutral zinc-air batteries are attracting enormous research interest due to their long lifetime and low cost. However, the sluggish kinetics of the air cathode in the neutral electrolyte reduces the catalytic performance and impedes the power density and energy efficiency of zinc-air batteries. In this work, we propose a universal, sustainable, and effective approach to improve the kinetics of the air cathode through a solar-energy-induced photothermal effect. By illumination of the cost-effective carbon-black-based cathode, the temperature of the air cathode increases from room temperature to 40.5 degrees C, thereby accelerating the kinetics for the electrocatalytic reaction and reducing the interfacial resistance of the zinc-air battery. Attributed to the sunlight-promoted reaction kinetics, the neutral zinc-air battery exhibits a higher power density of 2.89 mW cm-2 and longer cycling durability over 250 h, 116 and 156% times the one without light illumination, significantly improved in contrast to the one without light illumination. Furthermore, we demonstrated solar energy-driven and solar-enhanced charging in the daytime and discharging at night, potentially applying in distributed energy storage applications. The proposed sustainable solar-energy-promoted reaction kinetics of air cathodes will drive the development of efficient zinc-air batteries and also inspire the rational design of electrocatalytic electrodes in other electrochemical devices.