Integrated Composite Polymer Electrolyte Cross-Linked with SiO₂-Reinforced Layer for Enhanced Li-Ion Conductivity and Lithium Dendrite Inhibition

The rechargeable lithium metal battery with solid polymer electrolyte has high energy densities, desired safety, and extensive application prospect. However, its practical application is heavily hindered by dissatisfactory ionic conductivity and insufficient suppression of lithium dendrites due to poor mechanical strength. Achieving polymer electrolytes with high ionic conductivity and strong inhibition of lithium dendrites is a challenge. In this study, an integrated composite polymer electrolyte cross-linked with a SiO2-reinforced layer (P-RCL) was prepared by one-step in situ polymerization of vinylene carbonate, ethoxylated trimethylolpropane triacrylate, and methyl propenyl fumed SiO2. The P-RCL exhibited excellent room-temperature ionic conductivity (0.41 mS cm–1), high lithium-ion transference number (0.54), wide electrochemical window (5.1 V vs Li+/Li), and superior interfacial compatibility to Li metal. Moreover, the Li/LiFePO4 cell assembled with P-RCL electrolyte presented outstanding cycling performance (capacity retention of 79.1% for 1000 cycles at 2 C) and effective inhibition of lithium dendrites at room temperature. The reasonable design of advanced polymer electrolytes with integrated cell structure provides the possibilities for future high-energy lithium batteries.