A comprehensive study on the impact of heating position on thermal runaway of prismatic lithium-ion batteries

Thermal runaway (TR) is a primary safety problem on the application of lithium-ion batteries (LIBs), while TR characteristics and mechanism of LIBs under varied heating positions are still unclear. In this study, the impact of heating position on TR is investigated employing an experimental approach. Due to the prismatic battery shape, the heated positions of LIBs are selected as the front, bottom and side surfaces. The results indicate the maximum temperature, peak temperature increase rate and mass loss rate of LIBs are significantly affected by heating position. The onset times of safety valve opening, internal short circuit and TR are almost consistent when the battery bottom and side surfaces are heated. The maximum jet flow velocity occurs at the instant of the safety valve opening, and the values are 74.79 m/s and 77.26 m/s for bottom and side surface heating, which are about three times that of front surface heating. Compared with front surface heating, bottom and side surface heating modes cause more significant damage on LIBs owing to higher mean thermal conductivities and more intense exothermic reactions. This study can provide guidance for the safe design of LIBs and the prevention of TR propagation between LIB modules.