Numerical study on the critical characteristics of internal short-circuit hot spot in lithium-ion batteries

Abstract

High current density resulting from internal short circuit (ISC) in lithium-ion batteries leads to rapid local temperature rise, forming a hot spot. This study quantitatively characterized the critical properties of ISC hot spot in batteries. ISC hot spot in batteries exhibit two different evolution patterns. When the short circuit resistance approaches the internal resistance of the battery, the hot spot temperature reaches its peak at 1165 K. The thermal runaway characteristics of batteries vary depending on the short circuit resistance, with the hot spot growing and spreading rapidly when the resistance value is 30 mΩ. In addition, a modeling study was conducted to examine the critical characteristics of short circuit resistance. At a hot spot radius of 2 mm, the critical resistance was determined to be 281 mΩ, accompanied by a critical hot spot temperature of 562 K. Under subcritical conditions, the SEI film decomposes completely, while the electrolyte undergoes minimal decomposition. Interestingly, it was observed that the critical resistance and critical hot spot temperature decrease as the hot spot radius increases. Finally, the study quantified the effects of hot spot thermal conductivity, convective heat transfer coefficient, and hot spot position on the critical threshold of hot spots. These findings provide valuable references for the design of batteries with high critical thresholds.