Research on the Characteristics of Internal Short Circuits in Lithium-Ion Batteries Under Complex Condition: Nail Penetration Coupled with Charge/Discharge

This study systematically investigates the internal short circuit (ISC) characteristics of lithium-ion batteries (LIBs) for electric vehicles under nail penetration abuse coupled with charge/discharge operations. By establishing a nail penetration coupled with dynamic charge/discharge experimental platform and using commercial NCM pouch cells as test subjects, it comprehensively analyzes the effects of different charge/discharge operations (charging, discharging, resting) and C-rates (0.2 C–3 C) on battery surface temperature, voltage, current, mass loss, and thermal runaway behavior. The research finds that a mutual inhibitory effect exists between discharge operation and ISC, manifested as reduced discharge current along with decreased surge current, temperature rise rate, and voltage drop, significantly lowering the battery’s thermal runaway risk. In contrast, charging operation exacerbates ISC severity, causing increases in surge current, temperature rise rate, maximum temperature, and mass loss with higher C-rates, substantially enhancing thermal hazards. The study further reveals the underlying mechanisms: during discharge, a “Li+ competition” effect suppresses the short-circuit current, whereas during charging, the external power source and the battery jointly form the short-circuit current, intensifying heat generation. This research provides important experimental evidence and theoretical support for the thermal safety design and risk assessment of LIBs under operating conditions.