Size-Complementary, High-Concentration Zincophilic Solute Molecules for Wide-Temperature-Range Aqueous Zinc Metal Batteries

To realize stable aqueous zinc metal batteries that can operate over a wide temperature range, simple introduction of organic solutes into the electrolyte is required. However, common solute additives are poorly soluble in concentrated electrolytes for low-temperature applications. Herein, a strategy of using mixed solute additives is developed based on size-complementary zincophilic molecules with electron-rich groups. In the bulk electrolyte, the high-concentration short-chain acetamide (5 mol kg–1) dominantly regulates the hydrated Zn2+ and the hydrogen-bonding network for suppressing active H2O; at the anode interface, the complementary short-chain acetamide and long-chain silk amino acids form specific-adsorption and pH-buffering layers. Furthermore, the size-complementary zincophilic molecules reconstruct the double electric layer and solid electrolyte interphase to inhibit the side reactions of the Zn anode. Consequently, the zinc metal batteries have excellent cycle life (3400 h), Coulombic efficiency (99.7%), and wide-temperature-range adaptability (−60 to 60 °C), making them attractive candidates for practical applications.