Preventing thermal propagation in battery packs using enthalpy supported thermal barriers

Abstract The battery industry is driven by the need for an increased energy and power density in lithium-ion cells. Therefore, safety aspects are becoming increasingly important. Unfortunately, failure due to quality defects on cell level can neither be reliably predicted nor inhibited by the battery management system (BMS) forcing system manufacturers to implement safety measures in hardware on module level. In this paper, we investigate a novel thermal barrier placed between the individual cells to prevent thermal propagation (TP) in lithium-ion battery packs. A single cell failure may cause different exothermic reactions leading to an uncontrolled release of heat that can trigger subsequent reactions causing a thermal runaway (TR). In this case, the thermal barrier is able to protect neighbouring cells from overheating. Different test setups are used to characterize the functionality of the thermal barrier. Further experiments evaluate the influence of the energy distribution along different heat paths, for example via cell connectors, lateral contact areas and the cooling plate. The results illustrate the successful avoidance of propagation and the influence of the barrier thickness on the temperature behaviour but also show that the size of the setup (multi-cell vs. two-cell) used for propagation testing significantly influences the temperature behaviour.