Safety Analysis of Traction Batteries Based on Micro Internal Short Circuit Damage

The internal short circuit of a traction battery is one of the most typical failure mechanisms that can lead to thermal runaway, potentially triggering thermal propagation across the entire battery system. This phenomenon poses significant safety risks, especially in electric vehicles and large-scale energy storage systems. Therefore, it is essential to explore and understand the internal short circuit behavior to mitigate these risks. One of the most effective testing methods for reproducing an internal short circuit is the penetration test, where specific test conditions must be carefully designed based on the failure behavior. Among these conditions, the penetration step length plays a crucial role, as it directly influences the short circuit dynamics. Despite the importance of penetration step length, there is currently no standardized test procedure that dictates how to select the appropriate step size for different battery samples. This gap in standardization complicates the ability to replicate internal short circuit behavior consistently across various battery chemistries and configurations. In this study, penetration tests were conducted using a thin nail with varying step lengths to better understand the impact of these parameters on the electrical and thermal responses during failure. The analysis of the evolution of electrical and thermal parameters under different conditions provides valuable data for developing a universal test procedure. Such a procedure would facilitate the accurate simulation of internal short circuits, ultimately improving battery safety by helping engineers design more resilient battery systems and establishing benchmarks for industry-wide testing standards.