Improved Adhesion and Electrochemical Properties of Silicon/Carbon Composite Anodes By Using a Co-Polyimide Binder

Silicon (Si) is a promising anode candidates due to high theoretical capacity of 3500 mAh g -1 , which is approximately 10 times higher than the capacity of conventional graphite anodes. However, Si anodes have not been widely introduced into commercial lithium-ion batteries (LIBs), because they experience large volume expansion (~400%) during charge-discharge cycling. In order to alleviate this expansion during Li + insertion and extraction, the choice of binder for holding all of the components in the Si anode is very important. Although polyvinylidene fluoride (PVdF) has been widely utilized as a polymeric binder for commercialized LIBs over decades, lots of previous works have proved that PVdF could not provide the Si anodes with sufficient physical property to keep their original anode structure. To overcome the limitation of PVdF, a number of researchers have proposed new polymeric binder such as polyacrylic acid (PAA) [1], alginate [2] and polyimide (PI).[3-4] However, there is no LIBs adopting the only Si for their anode due to small but continuous electrolyte decomposition and pulverization for a long cycle life. Herein, we fabricate silicon/carbon (Si/C) composite anodes with highly adhesive and soluble co-polyimide (P84) binder. Their adhesion and electrochemical properties are evaluated by comparing conventional PVdF binder system. In addition, the loading level and density of electrodes are also changed to find an optimum binder contents or design parameters. Acknowledgements This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977). References [1] Magasinski, A.; Zdyrko, B.; Kovalenko, I.; Hertzberg, B.; Burtovyy, R.; Huebner, C. F.; Fuller, T. F.; Luzinov, I.; Yushin, G., Toward Efficient Binders for Li-Ion Battery Si-Based Anodes: Polyacrylic acid. ACS Appl. Mater. Interfaces 2010, 2, 3004-3010. [2] Ryou, M. H.; Kim, J.; Lee, I.; Kim, S.; Jeong, Y. K.; Hong, S.; Ryu, J. H.; Kim, T. S.; Park, J. K.; Lee, H., Mussel‐Inspired Adhesive Binders for High‐Performance Silicon Nanoparticle Anodes in Lithium‐Ion Batteries. Adv. Mater. 2013, 25, 1571-1576. [3] Choi, J.; Ryou, M.-H.; Son, B.; Song, J.; Park, J.-K.; Cho, K. Y.; Lee, Y. M., Improved High-Temperature Performance of Lithium-Ion Batteries through Use of a Thermally Stable Co-Polyimide-Based Cathode Binder. J. Power Sources 2014, 252, 138-143. [4] Choi, J.; Kim, K.; Jeong, J.; Cho, K. Y.; Ryou, M.-H.; Lee, Y. M., Highly Adhesive and Soluble Copolyimide Binder: Improving the Long-Term Cycle Life of Silicon Anodes in Lithium-Ion Batteries. Appl. Mater. Interfaces 2015, 7, 14851-14858. Figure 1