Tri-Layer Nonwoven Separator with Thermal Shutdown Function Fabricated through a Facile Papermaking Method for High-Safety Lithium-Ion Battery

Lithium-ion batteries have long been plagued by the safetyissueof thermal runaway. Improving the thermal stability and developingthe thermal shutdown function of the separators are considered reliablesolutions. Therefore, in this work, a tri-layer structured nonwovenseparator with a thermal shutdown function has been prepared via thepapermaking method. The separator comprises a polyethylene fiber layer,a microfibrillated cellulose fibers layer, and a polyethylene terephthalatenonwoven fabric layer. The polyethylene fiber layer endows the separatorwith a thermal shutdown function at 135 degrees C. The middle polyethyleneterephthalate nonwoven layer provides support, while the microfibrillatedcellulose fibers adjust the pore size. The separators exhibit excellentthermal stability, no shrinkage after heat treatment at 200 degrees C,and a wide thermal shutdown temperature window, thereby enhancingbattery safety. This research provides an approach to fabricatinghigh-safety thermal shutdown separators.