Thermal runaway delay characteristics in high-capacity lithium-ion battery modules incorporating various inter-cell thermal barrier pad types

Abstract

With increasing air pollution and energy shortages, rechargeable batteries have become a key focus as alternatives to petroleum energy. However, lithium-ion batteries may experience thermal runaway caused by mechanical damage or internal electrochemical defects, resulting in gas venting, material ejecta, fire, and in some cases deflagration of the released gases. This study assembled a battery module using 16 medium-to large-sized cells having a capacity of 181.2 Ah. To mitigate heat transfer within the module, inter-cell thermal barrier pads (TBPs) were created by combining mica with silicone, polyurethane foam, or steel, resulting in four different configurations applied to the module. Pad thicknesses of 1.35, 1.60, 1.85, and 2.0 mm were tested, but no significant correlation between total pad thickness and thermal runaway delay was observed. However, increasing the thickness of mica, which has the minimal thermal conductivity (0.4 W/m·K) among the materials tested, extended the delay time. Based on these results, TBPs having at least 0.6 mm in thickness and below 0.4 W/m·K in thermal conductivity are recommended for improving safety by mitigating heat propagation between cells. These findings are expected to contribute to the stability of rechargeable battery systems, especially in applications like electric vehicles and energy storage.