Hyper-Cross-Linked Nanoparticle Reinforced Composite Polymer Electrolytes with Enhanced Ionic Conductivity and Thermal Stability for Lithium-Ion Batteries

Solid polymer electrolytes (SPEs) have been considered as promising substitutes for liquid electrolytes in lithium-ion batteries due to their flexibility and nonflammability. However, there are still significant challenges to be overcome, such as the low ion conductivity and undesirable lithium ion transference number ( t Li + ). In this study, we prepare poly(ethylene oxide)-based composite solid polymer electrolytes (CSPE-HCPs) using hyper-cross-linked SiO 2 @PMMA- co -PS nanoparticles as the reinforcement. In contrast to the conventional SPEs, CSPE-HCPs can maintain dimensional thermal stability up to 260 °C. Meanwhile, the ionic conductivity of CSPE-HCPs can be up to 1.13 × 10 –4 S cm –1 at 30 °C and the t Li + can reach 0.51 at room temperature due to the porous hyper-cross-linked polymeric shell. Furthermore, LiFePO 4 /CSPEs/Li cells possess excellent rate performance and relatively stable cycle performance in addition to their outstanding electrochemical window (up to 5.3 V). It is demonstrated that these solid electrolytes reinforced by hyper-cross-linked composite nanoparticles can be a promising component to improve the performance of all solid-state lithium-ion batteries.