Effect of thermal runaway propagation depending on Lithium-ion battery module shape and placement with numerical simulation method

Abstract

Lithium-ion batteries are widely used where rechargeable electric power is required, such as electric vehicles, due to their high efficiency and high energy storage density. As the use of large-capacity lithium-ion batteries have increased significantly, the risk of fire due to thermal runaway of lithium-ion batteries has become more prominent. In this study, a numerical method was used to predict the timing of battery thermal runaway, and the propagation of thermal runaway considering the combustion reaction in the free stream area was studied. The CONVERGE, specific engine CFD program, is used for physical phenomenon and combustion simulation. Converge is a commercial program mainly used for cylinder flow, droplet behavior, and combustion inside the engine, but the latest version expands its support area to provide Hatchard-Kim thermal generation model for battery thermal runaway analysis. Detailed formulas and descriptions of each term are described in each section below. In order to prevent the propagation of battery thermal runaway, the thermal design of battery modules is very important. As a result of the study, as a whole, the wider the gap between the batteries, the lower the amount of thermal energy by heat transfer, resulting in delayed battery thermal runaway. In addition, it was found that the wider the space between the battery and the module wall, the more the combustion space is secured, which has a positive effect on preventing the propagation of thermal runaway. By comprehensively analyzing them, conclusions about the geometric elements necessary for battery module design were presented.