Effect of discharge operation on thermal runaway incubation process of lithium-ion battery: An experimental study

As the most critical safety issue for lithium-ion batteries (LIBs), thermal runaway (TR) may occur during operation, but the characteristics of TR under such conditions are not clear yet. Hence, the TR processes are studied under discharge conditions in this work. Firstly, TR is investigated under thermal abuse coupled with discharge to obtain the critical parameters at the cell level, compared with the test without discharge operation, the onset temperature of TR shows significant changes based on the residual state of charge (SOC), but the maximum difference of TR incubation time is only about 3%. Subsequently, the effect mechanism of discharge on TR is analyzed by clarifying the heat source contribution of the cells, the heat generated by the cell becomes the main driving force of TR before the discharge ratio reaches its maximum value, and the difference in total heat accumulation is caused by the scale of exothermic side reactions of LIB under the influence of SOC. The lower the cell SOC, the more heat is generated by the cell itself to trigger TR. Lastly, the effectiveness of discharge to mitigate TR propagation also has been verified from various perspectives at the module level. The results are expected to provide a reference for the safe application of LIBs and TR disaster mitigation.