Quantitative evaluation of thermal runaway in lithium-ion batteries under critical heating conditions to enhance safety.

Thermal stability in lithium-ion batteries is crucial for ensuring safety in energy storage systems and electric vehicles, where thermal runaway poses significant risks due to localized heating and the uncontrolled propagation of exothermic reactions. This study investigates the thermal dynamics in lithium-ion batteries under various critical heating conditions using a three-dimensional finite volume model. The research examines the effects of heating power, heating positions, and cell spacing on thermal runaway propagation patterns, focusing on both single-cell and multi-cell battery pack configurations. Analysis revealed that the direction of heat flow plays a significant role in thermal behavior, with side heating leading to faster runaway and central heating initially delaying initiation before accelerating at specific thresholds. Key findings indicate that lithium iron fluoride cathode materials exhibit superior thermal stability compared to nickel-manganese-cobalt-aluminum oxide types, and increasing cell spacing reduces the severity and timing of thermal runaway. A comparative evaluation of heating scenarios-side, central, and vertical-highlighted vertical 20 mm heating as the safest option. Moreover, the study details the heat release dynamics of different chemical processes: the negative solvent contributed the most significant heat generation (1.78 kW), while the solid electrolyte interphase layer produced the lowest (0.133 kW). Non-linear impacts of heating power were also observed, with a 7 kW/m configuration producing higher peak temperatures than 10 kW/m and resulting in an 18% reduction in thermal initiation time. These results improve the understanding of thermal runaway under varying conditions and provide insights for designing safer lithium-ion battery systems, with implications for thermal management in automotive, aerospace, and energy storage applications.