Nicotinamide Solid Cosolvent Enhanced Two-Electron Zinc Peroxide Chemistry for Stable Neutral Zinc-Air Batteries

Zinc-air batteries (ZABs) are promising energy storage systems due to their high energy density and sustainability. Neutral electrolytes effectively address the CO2 sensitivity and zinc corrosion issues in alkaline systems but face challenges such as hydrogen evolution reactions (HER) and sluggish oxygen reduction and evolution reactions (ORR/OER) dynamics. Herein, we introduce nicotinamide (NAM), a solid cosolvent with high donor number (DN) and acceptor number (AN) in neutral electrolyte. Due to its high DN, NAM readily coordinates with Zn2+ to weaken H2O’s dominance in the primary solvation sheath, reducing the required zinc salt concentration. NAM’s strong hydrogen bonding with H2O limits water mobility, suppressing HER and zinc corrosion. Its high AN enhances O2– affinity, enabling efficient two-electron zinc peroxide (ZnO2) chemistry. These advancements lead to remarkable stability, including nearly 2000 h in symmetric cells and 560 h in ZABs. Our electrolyte design highlights the potential of advancing neutral ZAB technology.