Thermal Runaway Characteristics of a Large Format Lithium-Ion Battery Module

The overheat abuse experiment of a 12S1P 37 Ah prismatic Lithium-ion battery module in a nominal energy of 1.65 kWh is conducted in this work. The cell behaviors and characterization in the process of thermal runaway propagation is investigated, including the gas eruption, the fire ejection, the flame combustion, the audio features, and the heat transfer, respectively. In the experiment, the central cell is heated on both sides until the pole temperature moves beyond 300 °C, the thermal runaway undergoes about 43 min and propagates from the central to both sides in the module, and all 12 cells burn. Results show that the first three runaway cells spout gas at first, and, then, emit sound with close amplitudes, frequencies, and energies, about 200 seconds earlier than the fire ejection. Then, the characteristic of the internal short circuit is the temperature rate zone of 1.0 K/s with time greater than 20 seconds. Moreover, the proposed thermal propagation coefficient is used to assess the thermal propagation capabilities of the runaway cells on their adjacent cells, and this explains the runaway sequence. It is anticipated that the experimental results can provide the deep understanding, thermal runaway warning, and evaluation method for the module safety design.