Application of a New Co-Polyimide Binder Material to Improved High-Temperature Performance for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) have been widely used for mobile IT devices and various electric vehicles (xEVs). Especially, since large-format LIBs are operated in the severe environments like -30 or 60 ^oC, their electrochemical performances and safety should be secured for at least 10 years. Recently, Yoon et al. reported that the degradation was closely related to the contact loss at the electrode/current collector interface and between active material particles¹. Thus, the dimensional stability of electrode should be maintained even at high temperatures.

In this study, the effects of a thermally stable co-polyimide-based polymeric binder on the performance of a cathode electrode are investigated. The introduction of co-polyimide (P84) into a conventional polymeric binder system based on polyvinylidene fluoride (PVdF) enhances the cycle performance under high temperature conditions (60 ^oC). Because of the inherent mechanical and thermal stabilities of the co polyimide, P84 retains outstanding adhesive/cohesive strength within the electrode composite, as well as between the electrode composite and the aluminium current collector. These findings are further supported by electrochemical impedance spectroscopic analysis, scanning electron microscope, and studies using a Surface and Interfacial Cutting Analysis System (SAICAS^®) ².

References

[1] T. Yoon, S. Park, J. Mun, J.H. Ryu, W. Choi, Y.-S. Kang,J.-H. Park, and S.M. Oh, J. Power Sources 215(2012) 312-316

[2] B. Son, M.-H. Ryou, J. Choi, T. Lee, H. K. Yu, J. H. Kim, and Y. M. Lee, ACS Appl. Mater. Interfaces, 6 (2014) 526-531

Acknowledgements

This research was financially supported by Chungcheong Leading Industry Promotion Project of the Korean Ministry of Trade. The authors also thank Sungmoon Systech Corp. in Korea for SAICAS^® measurement.