Numerical Analysis of Gas Diffusion Characteristics during Thermal Runaway in ESS Battery Module

- Energy storage system(ESS) is an eco-friendly energy storage system but it has safety problems due to explosions and toxic gas. Because the fire in the ESS system is caused by the thermal runaway of the battery, early detection would be essential to avoid fire damage. Gas composition and gas diffusion during thermal runaway are important factors for early detection. Most of this research has been conducted in the battery cells. However, the ESS system consists of battery modules. The spacing distance between battery cells and the module shape affects the gas diffusion for modules. Therefore, the present study aims to numerically examine the gas diffusion characteristics during thermal runaway inside the battery modules, and estimate the time required for detection. Simulations were performed for three cases depending on the fire locations. Numerical results showed that the CO 2 concentration in EES modules reached 5,000 ppm as the criterion for detection, within 20 seconds after a fire occurs. In addition, faster detection would be possible when the sensors are installed adjacent to the cells at which thermal runaway occurs.