A novel high-performance 3D polymer binder for silicon anode in lithium-ion batteries

Abstract

For high-capacity silicon (Si) anodes, the design of new binder is a feasible way to overcome the rapid capacity decay attributed to the large volume change of silicon (Si) anode in the repeated charging/discharging process. Here a newly designed binder with 3D structure was developed using CMC as the backbone, and acrylamide (AM), acrylic acid (AA) as the branch. The molecular structure was characterized by Fourier transform infrared (FTIR), and ethanol washing was applied for getting rid of unreacted monomers. The multifunctional binder with 3D structure and rich polar groups was prepared by cross-linking grafting. Polyacrylamide provides a strong adhesion and contributes to the formation of the solid electrolyte intermediate phase (SEI) layers on the surface of electrodes. The results show that CMC and polyacrylic acid with carboxyl groups not only strengthened the bonding force between the current collectors and the silicon nanoparticles (SiNPs), also improved the linkage among SiNPs. Therefore, the loading weight of commercial Si was about 0.75 mg cm−2, even after 150 deep cycles, and a high capacity of 1210.7 mAh g−1 was resulted in the Si anode. The prepared novel high-performance binder shows a potential application on the silicon anode in lithium-ion batteries.