Investigation of thermal runaway propagation characteristics of lithium-ion battery modules under different trigger modes

Rapid thermal runaway propagation (TRP) in lithium-ion batteries (LIBs) can cause safety accidents such as explosions or fires in the systems employing these batteries. Hence, the TR is a critical issue for the safety of LIBs. In this study, the TRP behavior of LIB modules under three typical triggering modes (heating, nail penetration, and overcharge) is investigated and compared. First, the three triggering modes are used to induce TR on a modified cell. Then, the TR and TRP models for each trigger mode are established, and the model parameters are identified based on experiments. Third, the TRP characteristics of battery modules under the three triggering modes are investigated. Finally, the energy flow distribution is determined during the TRP. The main conclusions are as follows: (1) The differences in TRP time and triggering temperature are obvious under different trigger modes in the early stage of TRP, but these differences are gradually eliminated in the later TRP stage. Therefore, TR trigger mode selection is critical during the initial stage of TRP. Specifically, the nail penetration trigger has the shortest trigger time while the heating trigger has the best comprehensive performance, allowing for good LIB testing operability and incurring low costs. (2) The energy flow distribution shows that more than 60% of TR energy is used for battery self-heating and more than 26% of the energy is emitted during cell material explosions. Therefore, TRP can be inhibited or delayed by improving the structure of the battery pack to reduce the temperature of the eruption or expel the ejecta to prevent explosions. (C) 2021 Elsevier Ltd. All rights reserved.