Enhanced Detection of Metallic Foreign Matter in Lithium-ion Batteries via High-potential Testing

Foreign matter defects introduced during lithium-ion battery manufacturing are the primary causes of battery failure and thermal runaway, posing significant safety risks. The development of practical and reliable detection methods for such defects is therefore crucial for enhancing overall battery safety and reliability. This paper presents a comprehensive mechanistic investigation aimed at identifying foreign-matter defects using insulation-detection techniques. Finite element modeling was employed to systematically investigate the influence of various types of foreign matter on the electric field distribution and insulation performance of the battery separator. The simulations demonstrated that metallic foreign matter causes localized electric field enhancement and may trigger dielectric breakdown under high-voltage conditions. Based on the simulation results and the corresponding mechanistic analysis, an innovative detection method utilizing high-potential testing protocols is proposed. This approach leverages the characteristic voltage changes associated with defect-induced short circuits for precise identification. Comparative evaluations show that the proposed method significantly outperforms conventional techniques, achieving a 41.7% higher detection rate for metallic foreign matter and exhibiting strong potential for real-time integration into manufacturing quality control systems.