Rapid ThermalShutdown of Temperature-Responsive ElectrolyteEnhancing the Safety Characteristic of Lithium-Ion Batteries

The safety issues of lithium-ion batteries (LIBs) with high energy density have received widespread attention in recent years. Here, a thermoresponsive electrolyte was fabricated and composed of a thermoresponsive monomer, 1,3,5-trioxane (TXE), and a conventional carbonate-based electrolyte, which got through a rapid liquid-to-solid phase transition upon a thermal-runaway process, offering a highly effective strategy to enhance lithium-ion battery safety. The dosage of TXE was optimized by giving consideration to the electrical performance and the thermal shutdown capability of the battery. The self-polymerization of TXE initiated by LiPF6 spontaneously took place at the thermal shock, which could form an effective heat shield that prevented short internal circuits and thermal runaway. The results showed that the LiCoO2||Li battery with the thermoresponsive electrolyte achieved shutdown within 500 s at 120 °C, while the cycling performance and rate capability at room temperature remained almost unaffected. This fast thermoresponsive electrolyte offered a pathway toward the design of intrinsically safe LIBs.