Weak Solvation Effect Induced Optimal Interfacial Chemistry Enables Highly Durable Zn Anodes for Aqueous Zn‐Ion Batteries

Aqueous zinc‐ion batteries (AZIBs) are emerging as one of the most reliable energy storage technologies for scale‐up applications, but still suffer from the instability of Zn anode, which is mainly caused by the undesirable dendrite growth and side reactions. To tackle these issues, we formulate a new aqueous electrolyte with weak solvation effect by introducing low‐dielectric‐constant acetone to achieve H2O‐poor solvation structure of Zn2+. Experimental and theoretical calculation studies concurrently reveal that such solvation structure can: i) relieve the solvated H2O related side reactions, ii) suppress the dendrite growth by boosting the desolvation kinetics of Zn2+ and iii) in situ form solid electrolyte interface (SEI) to synergistically inhibit the side reaction and dendrite growth. The synergy of these three factors prolongs the cycling life of Cu/Zn asymmetric cell from 30 h to more than 800 h at 1 mA cm−2/1 mAh cm−2, and can work at more harsh condition of 5 mA cm−2/5 mAh cm−2. More encouragingly, Zn/V2O5 ⋅ nH2O full cell also shows enhanced cycling stability of 95.9 % capacity retention after 1000 cycles, much better than that with baseline electrolyte (failing at ≈700th cycle). An electrolyte with weak solvation effect is rationally developed for aqueous Zn ion batteries (AZIBs). Benefiting from the reduced solvated H2O, boosted desolvation kinetics and in situ formed solid electrolyte interface (SEI) layer, Zn anode cycled in this electrolyte can deliver enhanced cycling stability.