I₃⁻-Mediated Oxygen Evolution Activities to Boost Rechargeable Zinc-Air Battery Performance with Low Charging Voltage and Long Cycling Life

An effective strategy to facilitate oxygen redox chemistry in metal-air batteries is to introduce a redox mediator into the liquid electrolyte. The rational utilization of redox mediators to accelerate the charging kinetics while ensuring the long lifetime of alkaline Zn-air batteries is challenging. Here, we apply commercial acetylene black catalysts to achieve an I₃⁻-mediated Zn-air battery by using ZnI₂ additives that provide I₃⁻ to accelerate the cathodic redox chemistry and regulate the uniform deposition of Zn²⁺ on the anode. The Zn-air battery performs an ultra-long cycle life of over 600 h at 5 mA cm⁻² with a final charge voltage of 1.87 V. We demonstrate that I⁻ mainly generates I₃⁻ on the surface of carbon catalysts during the electrochemically charging process, which can further chemically react with OH⁻ to generate oxygen and further revert to I⁻, thus obtaining a stable electrochemical system. This work offers a strategy to simultaneously improve the cycling life and reduce the charging voltage of Zn-air batteries through redox mediator methods.