Effects of Aniline Tetramer-Co-Acrylic Monomer Grafted to Polysaccharide Backbone As a Conductive and Adhesive Binder for High Capacity Si/C Composite Anodes

Conducting polymers such as polyaniline and polypyrrole have been sometimes described as a potential candidate binder for high silicon anode materials due to its low price, high conductivity, and simple synthesis. The manufacturing process of conducing polymerbased electrodes requires environmental-unfriendly organic solvents such as n-methylpyrrolidone. Due to the drawback, natural polysaccharides blended with the conductive polymers have been often investigated as water-soluble, electronically conductive, and adhesive binder to improve the electrochemical performance of the high-capacity Si anodes. However, the polymer blends are still needed to modify their properties through functionalization with some additional groups, for example, grafting with adhesive monomers and crosslinking for high adhesion strength. In this study, we first prepared aniline tetramer-co-acrylic monomer (AT-Am) by two step polymerization using 4-aminodiphenylamine in acidic solution at ~ 0°C, and then AT was reacted with acryloyl chloride monomer at room temperature for 3 hours to produce AT-Am monomer. Finally, AT-Am and pure acrylamide (AAm) monomers with various weight ratios are grafted and polymerized to the backbone of sodium alginate (Alg). Here AT and AAm have roles of electronic conduction and strong adhesion, respectively. This water-treatable alginate-graft-poly(acrylamide-aniline tetramer) (Alg-g-PAAT) was used as a conductive and adhesive binder for Si/C composite anodes to improve electronic conduction and adhesion ability when compared to natural Alg and Alg-g-PAAm. As a result, the Si/C anode containing Alg-g-PAAT yielded 800 mAh g-1 after 200 cycles with maintaining high columbic efficiency when compared to Alg-g-PAAm and physical blend between Alg-g-PAAm and AT.