Experimental Analysis of Thermal Runaway Propagation Risk within 18650 Lithium-Ion Battery Modules

A series of reproducible and repeatable experiments on thermal runaway propagation are conducted in this work. The impact of parameters on the process of thermal runaway propagation is explored, including the heating power, the state of the charge (SOC) and the cell spacing in the module, respectively. The cylindrical heaters with varying heating power are used to trigger thermal runaway in this work. The shape and size of the heater are designed to be the same as the sample cells. Therefore, the heat transfer mode between the heater and the cell is similar to that of the cells, where the heater is regarded as a thermal runaway cell. The results show that the module with 50% SOC releases more gases while the dramatic jet flame occurs in the module with 100% SOC. Besides, it takes around 240–280 seconds to propagate the thermal runaway event between the different layers in the battery modules. It is expected that the results of this experiment can provide the deep understanding and basic data for the module safety design.