Thermal-responsive electrolytes for reversible self-protection of electrochemical storage devices at excessive temperature

With the significant improvement of energy density and power density of electrochemical energy storage devices, a large amount of heat will be generated during operation, and fire or explosion may occur due to high internal temperature. However, the traditional method of controlling thermal runaway is slow and irreversible. Here, we investigate a reversible electrolyte system based on thermal-responsive polymers consisting of Pluronic F127, ionic liquid (IL) [EMIM]BF 4 , and a lithium salt. Pluronic-IL electrolyte responds by sol–gel transformation above the lower-critical solution temperature (LCST), which inhibits electrochemical energy conversion and effectively prevents thermal runaway at 160 ℃. We investigated the effects of operating temperature, lithium-ion concentration, and Pluronic concentration on electrochemical performance and proved that by regulating the concentration of Pluronic, the loss rate of capacitance can reach nearly 70%. It can be seen that this is a green and efficient method to control thermal runaway and may be practically used in lithium-ion batteries in the future.