Abstract: Thermal abuse and electrical abuse are the main reasons for triggering lithium-ion batteries into thermal runaway. In this paper, the thermal runaway experiments of LFP lithium-ion batteries were carried out by overheating using a plate and constant current overcharging with or without external sparks. The thermal runaway process and characteristic parameters such as temperature and voltage were collected and analyzed, the intrinsic thermal runaway characteristics of LFP battery cells and the combustion characteristics with external ignition source were elucidated. As the result shows, the tested LFP battery produced a lot of white smoke under overheating, with maximum temperature of 184 ℃. The LFP battery jet flame was observed ignited by external energy, and the maximum temperature was 740 ℃. The thermal runaway of the LFP battery under overcharge was more severe, and the maximum temperature was 450 ℃, but no flame was observed. The LFP battery jet flame was observed ignited by external energy, and the maximum temperature of the flame was about 1 000 ℃. The LFP battery fire ignited by the external ignition source was a B-type stable fire dominated by the electrolyte if it was not completely under thermal runaway. The violent jet flame was observed with the external heat or electricity adding again.

Key words: lithium-ion battery, thermal runaway, ignition source, combustion characteristic