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 acrylate-grafted cellulose separator polymer electrolyte (ACSPE) through the copolymerization of acrylate-grafted cellulose separator (ACS). This synthetic strategy leverages the abundant hydroxyl groups in the cellulose separator, which are substituted with acryloyl chloride to form an acrylate-grafted separator. 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|LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cells exhibit a long stable cycle life of 1000 cycles at 0.5 C/1 C with capacity retention of 75.6%, 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 mAh·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.