High-temperature resistant, super elastic aerogel sheet prepared based on in-situ supercritical separation method for thermal runaway prohibition of lithium-ion batteries

Thermal runaway (TR) propagation is considered the utmost safety issue of lithium-ion batteries (LIBs), which raised extensive concern. Using high-efficiency fireproof sheets to separate battery packs is one of the effective technologies to reduce the risk of TR propagation. Hence, we report a novel method, namely in-situ supercritical separation (ISS), to fabricate co-precursor aerogel sheets (CAS) based on an in-house device. ISS method can effectively reduce the preparation time of aerogel sheets to 3 h and greatly reduce the amount of solvent used without replacing or pressurizing additional solvent. More importantly, the proposed ISS method can effectively suppress the separation of the co-precursor heterogeneous substances, achieving homogeneous polymerization and improving the mechanical properties, high-temperature resistance and thermal insulation properties of the aerogel sheet. Specifically, CAS exhibits a compression strength of 638.5 kPa (50% strain), a low energy loss coefficient (0.238), and superior fatigue resistance (10,000 compressions). CAS has an ultralow thermal conductivity (i.e., 0.0197 W/(m·K)). The blocking functions of CAS are verified by a series of experiments where TR is triggered by abusive heating. Consequently, the TR propagation among fully charged LIBs with the highest temperature of up to 836.2 °C is successfully suppressed by 2-mm-thick CAS, yielding the maximum cell-to-cell temperature gap of 767 °C. Furthermore, it is proved that CAS with 35.7% wt aerogel is economical and capable of suppressing the TR propagation in the LIB module. The above results indicate that the CAS prepared by the ISS method is promising in applying to a safer LIB module.