Optimizing reaction pathways through inner surface ion confinement for high energy efficiency neutral zinc-air batteries

Abstract

Near-neutral rechargeable zinc-air batteries (ZABs) offer high energy density, safety, and economic benefits but suffer from higher polarization due to low-conductivity discharge products. Herein, we demonstrate an inner surface ion confinement effect within hydrophilic porous carbon to accelerate cathodic reaction kinetics of neutral ZABs. Operando electrochemical pH and in-situ XRD measurements reveal that microporous structure can temporarily store intermediate OH^-, shifting the reaction pathway to a more efficient electrolyte mechanism, similar to high-performance aprotic Li-O₂ batteries. This reduces basic zinc salt precipitation and ORR/OER overpotential, boosting energy efficiency from 46.0 % to 74.5 % at 0.1 mA cm⁻² and 2 mAh cm⁻². The resulting 10 Ah pouch cell and flexible belt-shaped cell offer scalable solutions for neutral zinc-air batteries across various applications, opening new avenues for high-performance metal-air batteries.