High Performance Cross-Linked Composite Gel Polymer Electrolyte Using Mesoporous and Reactive SiO2 Nanoparticles for Lithium-Ion Polymer Cells

Abstract

The rapidly expanding use of rechargeable lithium-ion batteries has led to intensive research on electrolyte systems with high electrochemical performance. However, current lithium-ion batteries have risks associated with leakage and fire hazards due to the high flammability of the organic solvents. In addition, the polyolefin separators used in lithium-ion batteries may shrink and even melt at elevated temperatures, which may cause a short circuit between the two electrodes in cases where unusually high heat is generated. Therefore, there is a pressing need for safer and more reliable electrolyte systems. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures as well as ambient temperature.