Enhancing Li+ transport kinetics of PEO-based polymer electrolyte with mesoporous silica-derived fillers for lithium-ion batteries

Abstract

Solid state batteries show great improvement of safety compared to batteries with liquid electrolytes. Polyethylene oxide (PEO) has been the most classic solid polymer electrolyte matrix. However, PEO based polymer electrolyte with lithium salt suffers from high crystallinity, poor Li+ transport kinetics and low ionic conductivity, especially at room temperature, which hindered its further application. Herein, a mesoporous silica derived active filler has been prepared with Li+ contained ionic liquid physically immobilized in the nanopore structure. PEO based solid polymer electrolyte with the active filler shows low crystallinity of 30% and a remarkable high ionic conductivity of 4.3 × 10−4 S cm−1 at 60 °C, at the same time maintaining a good mechanical strength of 1.28 MPa. The assembled lithium symmetric battery shows stable and long cycle performance. And the Li/LiFePO4 also shows stable cycling performance, maintaining 88.4% initial capacity after 80 cycles at 0.1C at 60 °C.