WHAT DOES THERMAL PROPAGATION MEAN?

Thermal propagation refers to a process in which the generated heat within a battery is spread to neighboring battery cells or modules. This can lead to a chain reaction effect in which overheating or a thermal runaway in one cell or module causes uncontrolled heating of the surrounding cells or modules.

Process and risks of thermal propagation

1. Trigger: The process often begins with a fault in a single battery cell, such as an internal short circuit, overcharging, physical damage or overheating. This fault leads to a rapid increase in temperature within the affected cell.
2. Thermal runaway: If the temperature in the cell exceeds a certain level, thermal instability can be triggered, in which exothermic chemical reactions in the cell take place in an uncontrolled manner. This leads to a further increase in temperature and the release of gases.
3. Heat transfer: The heat generated can be transferred to neighboring cells or modules. When these cells also exceed the critical temperature, a thermal runaway state occurs.
4. Chain reaction: This process can continue throughout the entire battery system, which can lead to a large-scale battery fire or even an explosion.

Meaning and measures

• Safety risk: Thermal propagation is a considerable safety risk, especially in large battery packs used in electric vehicles, energy storage systems and industrial applications.
• Design measures: To minimize the risks, modern batteries and battery packs are designed to limit the propagation of heat. This includes thermal insulation between cells, the use of cooling systems and the development of battery cells that are less susceptible to thermal runaway.
• Monitoring and protection systems: A battery management system (BMS) continuously monitors the temperature and other important parameters of the battery cells in order to detect anomalies at an early stage and take countermeasures before thermal propagation occurs.

Overall, controlling thermal propagation is a critical aspect of battery design and operation to ensure the safety of battery applications, especially those that store high amounts of energy.