High-Entropy Electrolyte for Scalable Zinc–Iodine Flow Batteries

Zinc metal anodes offer high capacity and intrinsic safety for aqueous batteries but are limited by sluggish interfacial desolvation and dendrite-induced instability under high utilization. Here, we design a high-entropy aqueous electrolyte by introducing multiple water-affine, low-molecular-weight alcohols at a fixed additive content, enabling solvent diversity to be tuned independently of concentration. Temperature-dependent transport analysis and electrochemical characterizations reveal entropy-assisted Zn2+ desolvation with a reduced activation barrier and a cleaner electrode–electrolyte interface, as evidenced by minimal solvent retention during deposition. This entropy-enabled interfacial regulation promotes preferential Zn (002) growth, suppresses parasitic reactions, and improves plating/stripping reversibility. When applied in a Zn–I2 flow battery, the electrolyte delivers a volumetric anodic capacity of 1905 mAh cm–3 in a 100 cm2 cell, together with high Coulombic and energy efficiencies. This work demonstrates entropy engineering of solvent environments as a strategy for stabilizing zinc metal anodes in scalable aqueous energy storage systems.