Comparison analysis on the thermal runaway of lithium-ion battery under two heating modes.

The thermal stability evaluation of materials in a soft-pack commercial cell is tested using C80 calorimeter, including anode, cathode, separator and full cell (mixing of the three materials including additional electrolyte). Thermal runaway characteristic of the commercial cell is tested on the accelerating rate calorimeter (ARC) with two heating modes, including internal heating mode and external heating mode. The results show that the thermal stability of internal material for tested cell follows the below order: anode<separator<cathode. The voltage drop is influenced by the consumption of cathode and separator, while the effect of anode consumption on the voltage can be negligible. Both onset temperature and critical temperature in external heating mode are larger than that in internal heating mode. Thermal runaway induced by high temperature of the tested cell can be divided into three stages: 1) the cell can work under normal mode and all the internal exothermal reaction can be ignorable, 2) the exothermal of anode which can be detected and the thermal runaway can be stopped by effective heat dissipation, and 3) the cathode reaction and separator melting which cause the cell voltage drop and thermal runaway of the cell is inevitable in this stage.