Volume 54

Internal Microstructural Changes and Side Reactions Induced by Copper Impurity Particles in Lithium-Ion Batteries Shun Chen, Jufeng Yang, Guodong Fan, Siyi Ye, Bangjun Guo, Yansong Wang, Xi Zhang

Abstract

Lithium-ion batteries serve as crucial energy storage carriers due to their numerous superior properties. However, metal impurities introduced during the manufacturing process can affect battery performance. The intrinsic impacts of these impurities have not yet been fully elucidated. In this study, pouch cells containing copper particle impurities are investigated. The results show that cells with impurities not only experienced micro-short circuits but also exhibited higher polarization compared to normal cells. Various material characterization techniques reveal that the increase in impedance is due to factors such as cracking of the anode graphite layer and localized lithium plating on the anode. Furthermore, the experiments reveal that the aluminum current collector in the short-circuit area dissolves and diffuses to the anode surface, forming deposits, while deposits also form around the impurity particles in the cathode. These phenomena can further degrade battery performance. The findings of this study enhance the understanding of the deep-seated effects of impurities in lithium-ion cells and provide theoretical insights for the manufacturing and detection methods of internal impurities in lithium-ion cells.

Keywords lithium-ion battery, metal impurity, internal short circuit, polarization increasing, collector corrosion