Experimental study on the effect of phase change material on thermal runaway characteristics of lithium-ion battery under different triggering methods

Although paraffin (PA) is a commonly used phase change material (PCM) for lithium-ion battery thermal management, its flammability may increase the risk of thermal runaway. This paper investigates the influence of PA on the thermal runaway, and the highly effective flame retardant hexa-phenoxy-cyclotriphosphazene (HPCP) was employed to suppress PA combustion and mitigate the thermal runaway hazard. Penetration and heating were used to induce thermal runaway. The battery surface temperature, the material temperature and the flame condition were recorded. The results show that penetration caused more violent reactions than heating, the battery temperature of penetration was 25 % higher than that of heating, while heating led to more harmful flame with a flame temperature over 1000 degrees C. PA delayed the onset of thermal runaway by 58.7 %, however, the higher temperature and longer burning time were a sign of increased danger. HPCP inhibited PA combustion, reducing the burn time by 35.7 %, while HPCP/PA delayed thermal runaway and controlled the battery flame, with a minimum of 43.5 % reduction in flame height. This study may provide a reference for the safe design of thermal management system for lithium-ion battery.