Montmorillonite-Containing Semi-interpenetrated Solid Polymer Electrolytes for High-Performance Lithium Metal Batteries

Solid polymer electrolytes (SPEs) have garnered significant attention due to their good structural tunability and processability. However, their application is still limited by low room-temperature (RT) ionic conductivity and poor compatibility with lithium metal anodes. A promising strategy to improve ionic conductivity involves designing semi-interpenetrating polymer networks, though it often results in compromised mechanical strength. The incorporation of clay minerals has proven effective in addressing interfacial compatibility issues arising from these mechanical deficiencies. Herein, we developed a composite solid electrolyte (MS-SPE) by integrating a semi-interpenetrated polymer with montmorillonite (MMT) nanosheets to simultaneously enhance ionic conductivity and Li anode compatibility. The resultant MS-SPE exhibits increased room-temperature ionic conductivity of 3.37 × 10–3 S cm–1 compared to 1.67 × 10–3 S cm–1 for the MMT-free SPE (S-SPE). Lithium symmetric cells with MS-SPE achieve an enhanced cycling stability at 0.3 mA cm–2/0.3 mAh cm–2, highlighting the optimized interfacial compatibility with the Li anode. Besides, LFP/MS-SPE/Li full cells retain 89% of their initial capacity after 1000 cycles at 1 C, outperforming the S-SPE based cells (72% retention after 1000 cycles). This strategy provides perspectives for addressing the challenge of the concurrent optimization of ionic conductivity and interfacial compatibility.