The thermal runaway of lithium batteries has become an urgent problem that needs to be solved today. In this study, polyimide aerogel materials with high temperature resistance and low thermal conductivity were prepared by supercritical drying equipment. Firstly, the activation energy distribution of the two pseudo-components of polyimide aerogels was calculated by TGA data at different heating rates, and then the optimal kinetic parameters were obtained. Secondly, a series of experiments were designed to study the blocking effect of polyimide aerogel films with different thicknesses (0.5 mm, 1 mm, 1.5 mm, and 2 mm) on the uncontrolled transmission of batteries, which showed that 2 mm film could successfully block the uncontrolled transmission of battery heat at 711.9 °C. 0.5 mm, 1 mm and 1.5 mm polyimide aerogel films can delay the thermal runaway of the battery, and the delay time was 182 s, 224 s and 259 s respectively. At the same time, the indicator gas was detected and analyzed, indicating that the barrier material can effectively reduce the content of CO2 gas and heat release rate. This study provides new enlightenment for the development of polyimide aerogels, and new ideas for the thermal insulation design of batteries.