Cellulose/PEGDA composite gel electrolyte with adjustable porosity and interfacial compatibility for lithium-ion batteries

Cellulose-based gel electrolytes used in Li-ion batteries have poor interfacial compatibility, leading to poor cycle and rate performance. Herein, the preparation of a cellulose/polyethylene glycol dimethacrylate (PEGDA) gel electrolyte, with good cycle stability, is reported. The interfacial compatibility, electrolyte uptake, and thermal stability of the gel electrolyte could be adjusted by changing the PEGDA content of the gel electrolyte. The porosity changed with the PEGDA content and the electrolyte uptake rate increased from 383.49 to 932.57%. The interfacial resistance of the cellulose/PEGDA gel electrolyte was 97.24 Ω, while that of the pure cellulose was 565.06 Ω. This can be attributed to the added PEGDA, which hinders the hydroxy activity of the cellulose, thus, improving the electrode–electrolyte interface performance. The excellent interfacial compatibility and high porosity led to excellent cycle stability. The capacity retention rate of the assembled battery after 100 cycles, at 0.5 C, was as high as 96.8%. In addition, the high electrolyte uptake rate from the 3D porous structure also improved the ionic conductivity and Li-ion migration number of the cellulose/PEGDA gel electrolyte.