Viscoelastic Soft Solid Electrolytes Enable Fast Zinc Ion Conductance and Highly Stable Zinc Metal Anode

Abstract Achieving both high ionic conductance and stable Zn metal anode simultaneously remains a challenge with current liquid and solid electrolytes. Here, a viscoelastic soft solid electrolyte (VSSE) strategy is presented that effectively balances Zn ion conduction and Zn anode stability. The VSSE is created by nano‐SiO 2 inducing a liquid‐to‐solid transition in a liquid solution containing Zn(BF 4 ) 2 salt dissolved in an oligomer (glycerol polyoxyethylene‐b‐oxypropylene ether, GPE) and water. The plentiful oxygen functional group in VSSE provides enough hydrogen bonding sites for water molecules to be completely hydrogen‐bonded to form a state without free water. The bound water serves as a Zn‐O coordination modulator that can weaken the strong Zn‐O coordination, lowering the dissociation energy for Zn ions, realizing fast Zn ion decoupling motion mode. Consequently, the VSSE gives impressive Zn ion conductance of (2.28 ± 0.07) ×10 −3 S cm −1 at room temperature 10–1000 times higher than reported solid polymer electrolytes. Simultaneously, the restricted molecular activity of bound water allows for excellent storage/cycle life of the Zn metal anode, which is confirmed by remarkably improved storage life (720 h), shelving‐recovery lifespan (850–1200 h), and cycling life (1400–2050 h). This study offers fresh perspectives on multifunctional electrolyte design strategies based on soft‐matter science.