Gel Polymer-Based Composite Solid-State Electrolyte for Long-Cycle-Life Rechargeable Zinc–Air Batteries

Developing high-performance, safe, and flexible solid-state electrolytes (SSEs) for rechargeable solid-state zinc–air batteries (ZABs) is becoming increasingly crucial but remains fraught with tremendous challenges. Herein, a novel multinetwork cross-linked composite gel electrolyte (PVAA-Cellulose) was constructed by introducing poly(acrylic acid) (PAA) and ultrafine cellulose to the poly(vinyl alcohol) (PVA) gel electrolyte. By virtue of the extensive porous network and hydrogen bonding, the PVAA-Cellulose SSEs achieve optimal water retention, thermal stability, and high ionic conductivity of 123 mS cm–1 compared with PVAA (mixture of PVA and PAA). The investigation of the effects of different SSEs on zinc anodes after ZAB cycling reveals that PVAA-Cellulose SSE can effectively inhibit dendrite growth and oxidation byproduct generation on zinc anodes, which contributes to the long-term cycling stability of ZABs. As a result, solid-state ZABs assembled with PVAA-Cellulose SSEs possess a high power density of 74 mW cm–2, a specific capacity of 724 mAh gZn–1, and a long cycle stability of 54 h as well as the outstanding flexibility exhibited by the flexible ZAB devices.