Inhibition effect on gas explosion of NCM pouch cell during thermal runaway by a novel efficient and economical aerosol explosion suppression agent

The explosion characteristics of gases generated from the overcharged thermal runaway (TR) process of NCM pouch cell were investigated. Specially, the gases mainly include H₂, CH₄, C₂H₄, C₂H₆, C₃H₆, and CO, and its maximum explosion pressure (MEP) concentration is 25% (volume ratio). The lower explosion limit of TR gas is 11.15%, and the upper explosion limit is 36.875%. To reduce the risk of an explosion from the TR gas, a unique aerosol explosion suppression agent (ASA) was prepared using simple three-component raw materials and a freeze-drying process. For the TR gas explosion at MEP concentration, the ASA-0.3 g can decrease MEP by 74.64% and maximum explosion pressure rate (MPR) by 97.67%. The ASA-0.5 g can completely inhibit the explosion. The mixed gas was 5.3 L, so the explosion suppression concentration of ASA is 0.095 g·L^-1. It is found that ASA consists of a gas mixture of N₂ and CO₂ and solid reactive particle (SRP). The anhydrous SRP contains 33% nanoscale KHCO₃ particles with a particle size mainly range of 0.1–1 μm. And the D90 of SRP is about 0.63 μm. The minimum extinguishing concentration of ASA is from 30 to 40 g·m^-3. Additionally, typical radiation spectra of potassium ions are found during the explosion suppression process, which indicates that potassium ions in SRP are involved in the reaction of ASA and TR gas during the explosion suppression process. Therefore, ASA can efficiently suppress the explosion of TR gas through its chemical inhibition mechanism, primarily by terminating free radical chain reactions.