Numerical Studying on the Influence of State of Charge and Internal Heat Generation on Lithium Battery Thermal Runaway

Abstract The widespread adoption of lithium batteries has raised concerns regarding safety due to the risk of thermal runaway. The mechanisms by which State of Charge (SOC) and internal heat generation influence thermal runaway in these batteries remain unclear. In this study, we utilize a three-dimensional electrochemical-thermal coupled model of lithium batteries to investigate the evolution of thermal runaway with increasing temperature by examining heat generation and temperature growth rate. Our findings indicate that: (1) both heat generation and temperature growth rate in lithium batteries during thermal runaway initially increase before eventually decreasing; (2) an increase in SOC leads to a reduction in lithium intercalation concentration at the negative electrode, resulting in decreased heat generation and lower peak temperatures during thermal runaway; (3) internal heat generation significantly impacts the critical time of thermal runaway, with higher heat generation associated with higher peak temperatures and increased risk. These results provide theoretical support for optimizing lithium battery safety and preventing associated fires and explosions.