Boosting anion-cation coordination by anti-solvents towards durable hydrous organic zinc batteries

Hydrated fluoroborates offer excellent nonflammability and their spontaneous hydrolysis can generate a ZnF2-based solid electrolyte interphase (SEI) on Zn anodes in hydrous organic Zn batteries. However, uncontrolled hydrolysis can lead to thick and uneven SEI, as well as cathode collapse. Here, we propose using anti-solvents to regulate the hydrolysis of fluoroborate anions via facilitating anion-cation coordination, resulting in a thin but compact ZnF2 SEI. Consequently, Zn anodes maintain stable cycling for over 1400 h at 1 mA cm−2, a high Coulombic efficiency (CE) of 99.4 % and high-rate capability up to 15 mA cm−2. Even at a challenging temperature of 60 °C, the Zn anode demonstrates over 1000 h of stable cycling with a CE of 98.0 %. Furthermore, the modified electrolyte alleviates V2O5 cathode dissolution, enabling extended cycling lifespan with a high CE close to 100 % in Zn||V2O5 full cells at room and high temperatures. Our findings suggest an avenue toward electrolyte design for developing high-performance Zn batteries and beyond.