An all-in-one polymer electrolyte enabled by acrylate-grafted separator copolymerization for high-performance lithium metal batteries

Polymer electrolytes featuring flexibility, processability and compatibility with large-scale roll-to-roll fabrication processes have emerged as promising candidates for solid-state lithium metal batteries. Herein, we have designed and synthesized an all-in-one free-standing polymer electrolyte (ACSPE) through the copolymerization of acrylate-grafted cellulose separator. This synthetic strategy leverages the abundant hydroxyl groups in the cellulose separator, which are substituted with acrylate chloride to form an acrylate-grafted separator (ACS). The resulting ACSPE exhibits a high ionic conductivity of 1.78 × 10^-3 S cm^-1 at room temperature, improved oxidation stability (5.57 V) and enhanced mechanical strength (10.0 MPa), indicating its high compatibility with high-voltage cathode, Li metal anode and scalable roll-to-roll production processes. Li|ACSPE|NCM811 cells exhibit a long stable cycle life of 1000 cycles at 1 C with 75.6% capacity retention, achieving stable performance across a wide temperature range from 0 to 60 °C. Furthermore, when paired with a 50 μm thin Li foil, full cells using NCM811 cathode with a mass loading of 6 mg cm^-2 exhibit a high discharge capacity of 191.0 mA h g^-1 at 0.1 C and maintain excellent cycling stability with a retention rate of 93.3% after 100 cycles. This study provides valuable insights into the chemical modification and design strategies for improving the processability and performance of polymer-based solid-state batteries.