A study of expansion force propagation characteristics and early warning feasibility for the thermal diffusion process of lithium-ion battery modules

Abstract

Research on thermal runaway warning and thermal propagation mechanism is of great importance for improving the thermal safety of lithium-ion batteries. This article focuses on the battery modules and examines the feasibility of using expansion force as thermal runaway warning signals. Results show that the utilization of the expansion force can detect battery failure 1314.61 s earlier and provide thermal runaway warnings 26 s earlier compared to that of temperature. This suggests that the use of the expansion force at the battery module level still shows good feasibility. In addition, the fluctuation mechanism of the expansion force during thermal propagation is further discussed by conducting experiments on the thermal propagation of modules with different sizes. Experimental results show that the superposition effect of adjacent battery expansion forces is the main influencing factor causing expansion force changes with two peaks. The fluctuation mechanism of expansion force can characterize the gas discharge behaviors of thermal runaway at different stages, such as the opening of pressure relief valves and multi-stage gas discharge during thermal runaway.