A Tri-Salt Composite Electrolyte with Temperature Switch Function for Intelligently Temperature-Controlled Lithium Batteries

The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic vehicles. The emerging of intelligent control in kinds of devices brings new requirements for battery systems. The high-energy lithium batteries are expected to respond or react under different environmental conditions. In this work, a tri-salt composite electrolyte is designed with a temperature switch function for intelligently temperature-controlled lithium batteries. Specifically, the halide Li3YBr6 together with LiTFSI and LiNO3 works as active fillers in a low-melting-point polymer matrix (polyethyleneglycol dimethyl ether (PEGDME) and polyethylene oxide (PEO)), which is further filled into the pre-lithiated alumina fiber skeleton. Above 60 degrees C, the composite electrolyte exists in the liquid state and fully contacts with the working electrodes on the liquid-solid interface, effectively minimizing the interfacial resistance and leading to high discharge capacity in the cell. The electrolyte is changed into a solid state below 30 degrees C so that the ionic conductivity is significantly reduced and the interface resistance is increased dramatically on the solid-solid interface. Therefore, by simply adjusting the temperature, the cell can be turned "ON" or "OFF" intentionally. This novel function of the composite electrolyte has enlightening significance in developing intelligently temperature-controlled lithium batteries. A tri-salt composite electrolyte is developed by adding Li3YBr6, LiTFSI, and LiNO3 into PEGDME/PEO. It reversibly transforms between solid and liquid through adjusting the temperature, with lithium-ion conductivity and interfacial contact dramatically changed. Correspondingly, the cells are blocked or conductive as turning "off" and "on" reversibly and flexibly. This switch function shows great potential for developing intelligently temperature-controlled lithium batteries. image