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.