Aqueous aluminum-zinc hybrid ion batteries with urea-based hydrated eutectic electrolytes

Aqueous polyvalent ion batteries are more suitable for large-scale industrial applications than non-aqueous polyvalent ion batteries due to their intrinsic cost-effectiveness and eco-friendliness. Developing new electrolyte and finding compatible anode and cathode materials are key to improve battery performance and reversibility. Herein, we present a novel aluminum-urea hydrated eutectic electrolyte (AUHEE) by coupling Al2(SO4)3·18 H2O and urea. Urea-assisted hydrated aluminum ions weaken the strong interaction between aluminum ions and water molecules, thus inhibiting hydrogen precipitation and anode passivation by suppressing water dehydrogenation. Unique solvation structure of electrolyte enables the V2O5/AUHEE/Zn cell to exhibit high discharge capacity (250 mAh g−1) and long cycle life (1500 cycles), providing new insights into the development of aqueous polyvalent ion batteries with high performance.