Low‐Cost, High‐Strength Cellulose‐based Quasi‐Solid Polymer Electrolyte for Solid‐State Lithium‐Metal Batteries

Abstract Solid‐state lithium‐metal batteries are considered as the next generation of high‐energy‐density batteries. However, their solid electrolytes suffer from low ionic conductivity, poor interface performance, and high production costs, restricting their commercial application. Herein, a low‐cost cellulose acetate‐based quasi‐solid composite polymer electrolyte (C‐CLA QPE) was developed with a high Li + transference number ( ) of 0.85 and excellent interface stability. The prepared LiFePO 4 (LFP)|C‐CLA QPE|Li batteries exhibited excellent cycle performance with a capacity retention of 97.7 % after 1200 cycles at 1 C and 25 °C. The experimental results and Density Function Theory (DFT) simulation revealed that the partially esterified side groups in the CLA matrix contribute to the migration of Li + and enhance electrochemical stability. This work provides a promising strategy for fabricating cost‐effective, stable polymer electrolytes for solid‐state lithium batteries.