Polyrotaxane-based electrolyte with excellent thermal stability for quasi-solid lithium metal batteries

Despite the high-energy densities, the safety problem of thermal runaway in lithium-ion batteries (LIBs) severely hinders their further application. Therefore, as an essential part of LIBs, the separator should ideally have good thermal stability at high temperatures. Here, a novel polyrotaxane (PR)-based gel polymer electrolyte (GPE) with good thermal stability is made by a simple solution casting method. The thermal shrinkage of the PR is less than 20% even heated at 200 degrees C; in contrast, the commercial Celgard 2400 separator undergoes dramatic deformation above 140 degrees C. The gel polymer electrolyte presents excellent compatibility in the cells of LiFePO4 and LiNi0.5Co0.2Mn0.3O2 cathode. The cell composed of Li/GPE/LiFePO4 presents good discharge performance and excellent stored performance. The cell composed of Li/GPE/LiNi0.5Mn0.3Co0.2O2 presents excellent capacity retention of 85.9% in 300 cycles while discharging at the 0.5 C rate. This GPE is promising to be applied to Li metal batteries with high safety and good cycle life.

Automated summary

This study addresses the safety issue of thermal runaway in lithium-ion batteries (LIBs) by developing a novel gel polymer electrolyte (GPE) with good thermal stability. The GPE exhibits excellent thermal stability at high temperatures and demonstrates outstanding electrochemical performance in different types of cells. It shows great potential for applications in lithium metal batteries with high safety and good cycle life.