Electrochemically Modified Interface Promoting the Oxygen-Electrocatalytic Kinetics in Near-Neutral Zinc-Air...

The development of near-neutral zinc-air batteries (ZABs) has been hindered by the sluggish oxygen reaction kinetics, severely limiting energy efficiency and power output. While recent advances in catalyst design have improved the intrinsic activity of electrocatalysts, their overall impact on battery performance remains limited. Here, an electrochemical modification strategy is presented that simultaneously enhances the surface properties of both the gas diffusion layer (GDL) and the bifunctional catalyst. The process introduces oxygen-containing functional groups on the GDL to improve electrolyte wettability and induce hydrous phase formation and structural defects in the catalyst, enhancing redox activity. These interfacial changes collectively enlarge the three-phase reaction region and promote efficient oxygen reduction and evolution kinetics. As a result, the modified near-neutral ZABs achieve a peak power density of 58.1 mW cm^-2, nearly fourfold higher than the unmodified system (15.4 mW cm^-2), along with a high energy efficiency of 59% (discharge voltage: 1.15 V, charge voltage: 1.95 V) sustained over 400 h of continuous cycling. In contrast, the unmodified cell shows 47.5% efficiency (0.95 and 2.00 V) with notable degradation. This interfacial engineering approach is broadly applicable to various catalysts and electrolyte systems, providing a universal and scalable route toward high-efficiency, high-power ZABs.