Visual and thermal imaging of lithium-ion battery thermal runaway induced by mechanical impact

Abstract

In this work, a rig was constructed to conduct destructive impact tests on cylindrical lithium-ion battery (LIB). The rig was intended to simulate the loss of mechanical integrity of the battery structure that might arise from heavy load and high impact. Thermal runaway behaviour of LIB from the tests was recorded by visual camera, thermal imaging and thermocouples. The findings revealed that there were two main hazards from mechanical impact on LIB. The first hazard originates from the reactive metallic electrodes that reached a very high temperature as a result of short-circuit and thermal runaway. Thermography of the aftermath showed that the battery content reached a temperature higher than 800 °C. The second hazard is the flame erupted due to the ignition of flammable electrolytes and combustible gases produced by battery components. As shown by thermography, the flame temperature can be higher than 500 °C. Even though violent failure behaviour was observed from the impact test, the large amount of heat was unable to induce thermal runaway reactions in the neighbouring cells. Thermography showed that all the surrounding cells remained at room temperature after the impact. Limited contact surface area retards the heat transfer process and deters the propagation of thermal runaway to the neighbouring cells.