Parametric Investigation of Thermal Runaway Mechanism in Lithium Battery Under Nail Penetration

The rapid progress and growing deployment of electric vehicles have elevated the safety of lithium-ion batteries to a top priority for both the public and the automotive industry. Among the various triggers of battery thermal runaway (TR), mechanical abuse stands out as a primary factor; yet, the internal physical and electrochemical processes occurring inside a cell during TR are still not fully understood. To bridge this knowledge gap and obtain a clearer picture of the cell’s internal behavior under TR conditions, a three-dimensional coupled electro-thermal model of a single battery cell is developed. Nail penetration simulations are performed under various operating conditions: nail radii of 3 mm and 5 mm, penetration speeds of 1.5 mm/s and 2.5 mm/s, initial state of charge (SOC) from 60% to 100%, surface heat transfer coefficients of 5–20 W/(m2·K), and different penetration locations (center, near electrodes, corners). The results show that a larger nail radius (5 mm) leads to a peak temperature of 538 K, and higher initial SOC (100%) results in a voltage drop of 0.8 V. The highest local temperature (480 K) occurs near the positive electrode. These findings offer a robust simulation-based approach for evaluating battery safety under nail penetration. This work offers a robust simulation-based approach for evaluating the safety performance of lithium-ion batteries under nail penetration scenarios.