Efficient and lightweight battery protection film with a bionic polar bear structure in extreme environments

The safety of Li-ion batteries in extreme environments (low or high temperature) is the first issue to be solved in the development, and passive thermal protection is the most cost-effective approach. Conventional aerogel insulation needs to solve the application's problem of falling powder and bending problem. We prepared a hollow SiO₂ protection film inspired by polar bear hollow hairs using the electrostatic spinning microemulsion method without complex coaxial spinning needles. We tested the thermal stability, insulation performance, mechanical properties, and bending fatigue of the insulation film and discovered that this lightweight hollow SiO₂ fiber film had low thermal conductivity and remained flexible. The temperature reduction of front and back the fiber membrane reached 82.9 % for the battery module 3C overcharge thermal runaway, which successfully prevented explosion spread. Also the bionic insulation could protect battery performance at low temperature, which had a positive effect on solving the battery safety problem in extreme environments.