A multi-factor evaluation method for the thermal runaway risk of lithium-ion batteries

To systematically and quantitatively establish a multi-factor evaluation method for the thermal runaway risk of lithium-ion batteries (LIBs), the fuzzy analytic hierarchy process was adopted in this paper. The own hazardous factor of battery, hazardous factor of vented gases, jet fire and high-temperature mixture (JFHM), ejected powder and their corresponding sub-factors were evaluated and analyzed. Combined with literature, the model of multi-factor evaluation method was established and the index system was determined. The pair-wise comparison matrixes for the thermal runaway risk were drawn, the triangular fuzzy method was used to calculate and the evaluation weight was obtained. The factors' ranges of the criteria risk grades were quantitatively determined. The risk of thermal runaway consequences under the selected abuse condition was analyzed with a case study. The result shows that the thermal runaway risk from LIBs under the selected abuse condition is level III: the LIB is more dangerous after thermal runaway. Meanwhile, in this method, the lower explosion limit of gas and the maximum height/ length of the JFHM are the two factors with the greatest weights. In the actual design and use process, people should pay attention to the protection of the runaway gas explosion and the harm of JFHM.