Boosting Cathode Activity and Anode Stability of Zn‐S Batteries in Aqueous Media Through Cosolvent‐Catalyst Synergy

Abstract Aqueous Zn−S battery with high energy density represents a promising large‐scale energy storage technology, but its application is severely hindered by the poor reversibility of both S cathode and Zn anode. Herein, we develop a “cocktail optimized” electrolyte containing tetraglyme (G4) and water as co‐solvents and I 2 as additive. The G4‐I 2 synergy could activate efficient polar I 3 − /I − catalyst couple and shield the cathode from water, thus facilitating the conversion kinetics of S and suppressing the interfacial side reactions. Simultaneously, it could stabilize Zn anode by forming an organic–inorganic interphase upon cycling. With boosted electrodes reversibility, the Zn−S cell delivers a high capacity of 775 mAh g −1 at 2 A g −1 , and retains over 70 % capacity after 600 cycles at 4 A g −1 . The advances can also be readily generalized to other ethers/water hybrid electrolytes, showing the universality of the “cocktail optimized” electrolyte design strategy.