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

Abstract

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 H2 O-poor solvation structure of Zn2+ . Experimental and theoretical calculation studies concurrently reveal that such solvation structure can: i) relieve the solvated H2 O 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/V2 O5  ⋅ nH2 O 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).