Development of a zinc-air flow battery with acetonitrile-based organic electrolyte

Rechargeable zinc-air batteries are promising candidates for next-generation energy storage systems due to their high theoretical energy density, cost-effectiveness, and environmental compatibility. However, conventional aqueous alkaline electrolytes suffer from drawbacks, including hydrogen evolution, electrode corrosion, and limited electrochemical windows, hindering their long-term stability and application. We report a zinc-air flow battery using a non-aqueous acetonitrile (ACN)-based electrolyte with Zn(ClO₄)₂ salt. The low viscosity and moderate dielectric constant of ACN promote fast Zn2+ transport and facile desolvation, while spectroscopic analyses reveal strong Zn2+-ACN interactions forming a stable solvation structure. The dendritic Zn anode and carbon-based air cathode enhance interfacial kinetics, enabling reversible Zn plating/stripping and oxygen electrochemistry. In coin-cell tests, the Zn(ClO₄)₂-ACN electrolyte shows a low polarization gap (ΔV ≈ 0.92 V at 0.1 mA cm−2) and durable cycling over 360 h. A Flow-cell architecture allows evaluation under high-current and application-relevant conditions. The optimized flow battery delivers a peak power density of 53.3 mW cm−2 and stable operation for 200 h with a nearly ideal coulombic efficiency. These results demonstrate that ACN-based organic electrolytes can overcome the limitations of aqueous systems, offering a scalable pathway for developing practical Zn-air flow batteries with ACN-based organic electrolytes.