PVA-based high carboxyl group substituted modified cellulose nanofiber composite hydrogel for flexible new air battery

Zinc-air battery (ZAB) with high theoretical energy density and low-cost characteristics has become one of the future candidate energy storage devices for flexible and portable electronic devices. If the application of ZAB in this field is to be promoted, how to improve the performance of solid-state batteries (such as cycle stability, discharge capacity) is the main problem at present. Flexible solid electrolyte plays a vital role in it. In this work, Carboxyl modified cellulose nanofibers (C-CNFs) was prepared by controlling the degree of carboxyl modification, and polyvinyl alcohol (PVA)-based cellulose composite gel polymer electrolyte (GPE) was synthesized. The optimal PVA-based composite GPE was selected to exhibit high ionic conductivity (0.31 S cm−1), excellent water retention and good tensile mechanical strength under environmental conditions. The assembled flexible zinc-air battery (ZAB) exhibits excellent cycle stability, discharge performance and power density. ZAB based on PVA-C-CNFs GPE can work continuously and stably for 50 hours, and at the same time has high cost-effectiveness and safety.