Study on the comprehensive multisource thermal runaway failure characteristics and cooling effects of extinguishing agents in 280 Ah batteries

The safety of energy storage systems relies heavily on thermal runaway early warning protection and cooling intervention of fire extinguishing agents for large-capacity lithium iron phosphate batteries (LiFePO4). An integrated platform was established to trigger thermal runaway fires through heating abuse and coordinate with extinguishing agents at the cell/module level. Key indicators of the battery thermal runaway evolution process were constructed, identifying 16 multidimensional signal characteristics representing thermal runaway failure, with the hydrogen gas production rate and contribution ratio being highlighted as critical early warning signals. Based on the maximum voltage drop rate and duration of soft short circuits, the cooling effects of perfluorohexanone-based extinguishing agents were explored to reduce the risk index of thermal runaway explosion to the lowest level. Through gas concentration tests under various conditions, a three-level early warning mechanism for thermal runaway was established, setting thresholds for hydrogen, volatile organic compound, carbon dioxide, smoke, and gas temperature. The establishment of warning indicators and mechanisms is crucial for improving the early warning and protection strategies of energy storage systems against thermal runaway.