Flexible Al₂SiO₅ Nanofiber Membranes for Thermal Insulation in Lithium-Ion Batteries

The performance loss in extreme environmental temperatures and thermal runaway (TR) is a major drawback of lithium-ion batteries (LIBs), raising significant concern. This study employed electrospinning to prepare flexible Al₂SiO₅ nanofiber membranes for thermal insulation in batteries. These membranes exhibited low thermal conductivities of 0.03487, 0.03512, and 0.07384 W/(m·K) at −25, 25, and 800 °C, respectively, indicating that these membranes are excellent for thermal insulation. With the fiber membrane in place, the cell surface temperature changed slower toward ambient temperature than the control group. During charging and discharging at −25 °C, batteries wrapped with the fiber membrane exhibited a significantly higher capacity than the control group. In the case of thermal abuse, the battery module with fibers exhibited a 1608 s delay from the heating start to the TR onset compared to the battery module without membranes, and the time gap between safety valve rupture to TR onset was also 503 s more than the battery module without membranes. The fiber membranes have less effect on the surrounding cells than the control group, thus significantly improving battery safety.