Electric vehicle (EV) battery packs have undergone substantial advancements in recent years, driven by engineering design improvements, material innovations, and increasingly stringent regulatory enforcement. These developments have enabled battery packs to become more energy-dense, which is essential for extending driving range and improving overall vehicle performance. However, with increased energy density comes a heightened risk of thermal events, such as thermal runaway, which continue to raise concerns regarding vehicle safety, reliability, and long-term durability.
This review focuses on the critical role that thermal insulation materials play in mitigating the impact of such thermal events within EV battery systems. It presents an overview of commonly used thermal insulation materials, emphasizing their chemical composition, thermal resistance, and mechanical integrity under extreme conditions such as high temperatures and physical stress. The ability of these materials to maintain performance during thermal abuse is essential for protecting both the battery and surrounding vehicle components.
In addition to material properties, the review explores standard methods for evaluating flammability, including flame retardance tests like UL94. It also compares various torch and grit-type flammability tests to highlight differences in methodology and performance metrics. These comparisons are crucial for identifying insulation materials that can withstand severe thermal conditions without compromising safety.
Beyond flammability, high temperature, smoke, and other important considerations such as thermal properties, environmental durability, corrosion resistance, and dielectric strength will be discussed with examples. These factors contribute to the overall effectiveness and reliability of insulation materials in EV applications. By understanding and optimizing these properties, engineers can better design battery packs that are not only high-performing but also safe and resilient under demanding operating conditions.