A comparative investigation of charging conditions on thermal runaway of lithium-ion batteries induced by different incident heat fluxes

Thermal runaway poses a great challenge for lithium-ion battery applications, an in-depth delve into the thermal characteristics and fire behaviors is paramount to battery thermal management system design and fire prevention. This work intends to investigated the thermal characteristics and fire behaviors of batteries when subjected to different charging rates and without charging treatment under different incident heat fluxes by using of a cone calorimeter. Experimental results indicate that the battery thermal risk increased with increasing charging rate, manifesting lower internal short circuit and onset temperature, as well as higher maximum temperature and heat release rate. It was observed that the flame extension length rose from 32.85 mm at 0.5 C to 68.85 mm at 3 C during the venting stage. In addition, the charging time terminated prematurely which led to the final SOC declined by 5.2%-22%. Thermal runaway onset time reduced by between 746 s and 962 s as the incident heat flux increased from 20 kW/m2 to 50 kW/m2. Furthermore, the increasing thermal runaway duration without charging treatment, suggesting the accelerating effect of charging current. Subsequently, a semiempirical ignition model was developed. This work aims to give a comprehensive understanding of thermal runaway characteristics in the presence of dual charging and heat flux conditions and hopes to provide meritorious references for the safety of lithium-ion battery applications.