Vertical channel‐structured cyanoethylated bacterial cellulose/polyethylene oxide composite solid electrolyte for all‐solid‐state lithium batteries

Abstract Solid polymer electrolytes (SPEs) have gained remarkable development within the realm of new energy resources. With its improved electrochemical stability and environmental‐friendly sustainability, bacterial cellulose (BC) has emerged as a promising candidate for applications in SPEs. Herein, bacterial cellulose was chemically cyanoethylated and integrated with lithium bis(trifluoromethanesulphonyl)imide/polyethylene oxide (PEO) based SPE. Some vertical channels are formed when trace amounts (0.5 wt%) of cyanoethylated bacterial cellulose (BC‐CN) are added to PEO‐based SPE, as revealed by SEM. This formula's corresponding PEO‐based SPE presents the highest ion conductivity of 5.7 × 10 −4 S cm −1 at 60°C. The ion migration activation (Ea) deduced from the Arrhenius equation is 0.48 eV, lower than the value of 0.82 eV for the pristine PEO SPE. Besides, the Li + migration number of this modified PEO‐based solid electrolyte is calculated to be a relatively high value of 0.33, while that of its counterpart, the pristine PEO SPE, is as low as 0.06. The all‐solid‐state lithium battery with PEO/0.5%BC‐CN SPE can operate stably for 115 cycles, which is longer than the 80 cycles achieved with the pristine PEO SPE. This study introduces a novel strategy for creating modified BC composites PEO‐based SPE. Highlights Bacterial cellulose was chemically cyanoethylated. Cyanoethylated bacterial cellulose composite polyethylene oxide (PEO)‐based solid polymer electrolytes (SPEs) are prepared in DMF. Opening pores penetrate the surface of the PEO/0.5% cyanoethylated bacterial cellulose (BC‐CN) SPE membrane. PEO/0.5% BC‐CN shows ionic conductivity of 5.7 × 10 −4 S cm −1 at 60°C. Full cell with PEO/0.5% BC‐CN performs stably for 115 cycles.