Comparative analysis of multidimensional signals evolution in prismatic and pouch LiFePO4 batteries under thermal abuse

Prismatic and pouch configurations are two distinct packaging formats for lithium-ion batteries, with significant differences in failure behavior. However, the effect of packaging formats on cell-level thermal runaway and its propagation at the module-level has not been thoroughly understood, especially from the perspective of multidimensional signal evolution. In this study, a comparative analysis of the failure behaviors in prismatic and pouch batteries is conducted under various thermal abuse scenarios, at both the cell and module levels. This study examines a range of multidimensional signals, simultaneously including expansion force, gas concentration, gas temperature, battery temperature, and voltage. Our findings reveal four distinct peaks in the expansion force of the prismatic cell, in contrast to only two for pouch cells. Both cell types display a consistent venting voltage of approximately 3.35 V, with gas emissions detected after venting. Notably, the venting force and temperature of the prismatic cell reach up to 5577 N and 121.2 °C, respectively, which are approximately 3000 N and 57.0 °C higher than those of the pouch cell. Especially, the abnormal rise rate in expansion force at 5 N/s emerges as the earliest detectable signal among the four signals regardless of the packaging formats, offering a lead time of over 80 s before venting occurs, and 444 s prior to the onset of thermal runaway at both cell and module levels. Additionally, a temperature rise rate exceeding 0.2 °C/s is a critical signal for an impending TR event. This study deepens the understanding of failure mechanisms unique to different battery packaging formats and guides early safety warning design for energy storage applications.