Thermal behaviour and thermal runaway propagation in lithium-ion battery systems – A critical review

A large number of Lithium-ion battery packs are used for electromobility applications in power electric vehicles. The battery cells are connected in series or in parallel depending upon the power requirements for types of cylindrical, pouch, and prismatic battery cells. Particularly under functioning condition of an electric vehicle, several charging and discharging cycles in battery cells results in heat generation inside a particular cell which have an influence in adjacent battery cells as well. Overheating can cause thermal runaway in one or more cell and the heat transfers to adjacent cells which results in thermal propagation. The higher the number of cells the higher chance of fire to propagate. To mitigate the thermal propagation in battery cells a number of prevention techniques can be employed. This study provides an overview of the challenges associated with thermal runaway to understand the internal defects within battery. In addition, generation, propagation of thermal runaway and the parameters affecting thermal runaway within lithium-ion battery have been elaborated. The importance of employing a number of cooling mechanisms or preventing strategies such as air cooling, heat pipe cooling, hybrid cooling etc. for the prevention of fire have also been discussed. Based on those criteria several advancements of cooling strategies including fire-resistant coatings, use of additives, use of positive temperature co-efficient materials, current interrupt devices, thermal fuse, insulation techniques have been introduced. Moreover, this study discusses on the mitigation strategies at system level by incorporating sensors and smart battery management system to monitor, control and enhance the performance of the battery modules.