Investigation on thermal runaway of 18,650 lithium ion battery under thermal abuse coupled with charging

Thermal runaway (TR) is the most critical safety issue of lithium ion battery (LIB), and more uncertain hazard factors may be introduced under working conditions. The TR under thermal abuse coupled with charging is investigated in this study. The thermal-induced TR processes at various current rates are analyzed, the results indicate that the cells present a higher thermal risk with lower TR onset temperature and higher maximum temperature with increasing current rate. As the charging rate increased from 1 C to 5 C, the proportion of charging heat in total heat production of the cell increased from 2.0% to 28.1% before TR, coupled with rich lithium in anode at high SOC, promoted the TR to be triggered prematurely. In addition, the average incubation time of TR experienced significant decrease of 51.6 s (7.7%) compared to cell that was heated after charging at 5 C, where it is found that the heat generation of charging promote the occurrence of electrical fault and thus shorten the TR incubation process. This work delivers an underlying analysis of TR under thermal abuse coupled with charging, and which is expected to provide reference for the safety of application of LIBs and thermal management system design of LIBs. •Thermal runway is synthetically studied under thermal abuse coupled with charging.•The cells present higher TR risk under thermal abuse coupled with charging.•Rich lithium in anode and charging heat impel the thermal runaway occurrence.•Charging heat promote the electrical fault and thus shorten the TR incubation.