Effects and Mechanism of Thermal Insulation Materials on Thermal Runaway Propagation in Large-format Pouch Lithium-ion Batteries

The large heat transfer area of large-format lithium-ion batteries primarily facilitates conduction heat, which is responsible for triggering the thermal runaway of adjacent cells. Therefore, the primary consideration is to utilize thermal insulation materials between cells in order to slow down or prevent the process of thermal runaway propagation. In this study, three varieties of thermal insulation materials were employed to insulate individual cells within a module comprising three large-format pouch cells. These materials include pre-oxygenated wire aerogel (AG-ST-POF), polymer-coated pre-oxygenated wire aerogel (PC-AG-ST-POF), and silicone (SI). The study experimentally examined the thermal runaway propagation (TRP) behavior of the battery module under conditions without insulation materials and with various types of insulation materials. The impact of thermal insulation materials on the TRP among cells was analyzed. The study revealed that none of the three materials completely suppressed the propagation of thermal runaway, although they did impede its progress. The overall impact of AG-ST-POF surpassed that of SI and PC-AG-ST-POF. Furthermore, the mechanism by which thermal insulation materials influence TRP was explored. The results of the thermophysical properties testing suggest that evaluating the impact of materials on TRP solely through thermal conductivity is not a reliable approach. Alternatively, the maximum service temperature and thermal diffusion coefficient are critical parameters for the selection of thermal insulation materials. This study can provide a valuable reference for process engineering design and application in the context of lithium-ion batteries, with the aim of mitigating the risk of TRP.