Thermal runaway and combustion characteristics, risk and hazard evaluation of lithium‑iron phosphate battery under different thermal runaway triggering modes

A comprehensive understanding of the thermal runaway (TR) and combustion characteristics of lithium-ion batteries (LIBs) is vital for safety protection of LIBs. LIBs are often subjected to abuse through the coupling of various thermal trigger modes in large energy storage application scenarios. In this paper, we systematically investigated the TR and combustion characteristics of heating + overcharge and heating + short circuit at different temperatures and compared them with individual heating, overcharge, and short circuit. Additionally, we analyzed the TR and combustion hazards of different thermal triggering modes using Analytic Hierarchy Process (AHP). The results show that heating + overcharge has a shorter time of safety valve opening and TR, a lower thermal runaway temperature, a higher peak heat release rate (HRR), and is more hazardous than heating and overcharge. Compared with heating, heating + short circuit shortens safety valve opening time and increases peak HRR; versus short circuit, heating + short circuit lowers TR temperature and TR time, enhances peak HRR, and causes a higher hazard. The AHP analysis indicates that the TR temperature and fire growth index are the most critical parameters and that heating + overcharge has the biggest TR and combustion hazards; besides, heating + short circuit exists higher TR risk and hazards than short circuit and greater combustion risks and hazards than heating. The research findings can provide valuable guidance for protecting and preventing energy storage LIBs TR.