Experimental study on thermal runaway behaviors of 18650 li-ion battery under enclosed and ventilated conditions

Abstract

A novel study was done using a designed 6.7L chamber for experiments under both enclosed and ventilated conditions. Under enclosed condition, for LIB (li-ion battery) above 0% SOC (state of charge), the cases ruptured. Above 50% SOC, an explosion was even triggered. Though the analysis of collected gas from the enclosed condition, the flammable gas (e.g., CH4, CO) concentration increased as SOC increased, even a gas explosion occurred. Under ventilation, the tendency of case rupture decreased and the gas explosion risk was reduced. Whether the case rupture occurred was depended on the rate of generated gas venting. Fick's Law was adopted to describe this phenomenon. It was found that the external pressure was the key factor impacting the case rupture. This work studied the LIB thermal runaway behaviors from a novel perspective, and provided a reference for the safety protection of the LIBs.