Thermal runaway hazard characteristics and influencing factors of Li-ion battery packs under high-rate charge condition

In a special environment such as a high-rate charge or discharge one, the positive and negative electrode materials of a lithium ion battery may undergo a chemical exothermic reaction with an electrolyte and a binder and release a large amount of heat to cause thermal runaway, resulting in harmful consequences. In this paper, high-rate charging experiments of different types of 18650 Li-ion battery packs were performed to study the behavior and influencing factors of Li-ion battery packs when thermal runaway occurred. Automatic test equipment with battery comprehensive parameters was adopted, and a Li-ion battery thermal runaway test device was designed and used to test a series of Li-ion battery packs under high-rate charging conditions. The series of tests were conducted under different conditions of different cell spacing, pick-up point positions and connection modes. Results showed that under the above three different conditions, the initial time and the initial temperature of the thermal runaway of the Li-ion battery packs, the maximum temperature of thermal runaway and the position where the first thermal runaway battery occurred showed some regular changes.