Incorporation of Aniline Tetramer into Alginate-Grafted-Polyacrylamide as Polymeric Binder for High-Capacity Silicon/Graphite Anodes

The popular 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. However, the manufacturing process of conducing polymer-based electrodes requires environmental-unfriendly organic solvents such as n-methylpyrrolidone. In this study, a new design on polymeric binder is proposed for the high-capacity anodes. The effective addition of conductive aniline oligomers to adhesive alginate-<i>graft</i>-polyacrylamide binder improves the performance of the silicon/graphite composite electrodes. To do this, three-step <i>in situ</i> polymerization is adopted to synthesize adhesive and conductive alginate-<i>graft</i>-poly(acrylamide-<i>co</i>-acrylamide aniline tetramer). A small amount of aniline tetramer added to the binder, of 1.25 wt.%, is enough to enhance electronic and ionic transport through the silicon-based anode, while maintaining electrode adhesion. Consequently, the silicon/graphite electrode containing the alginate-<i>graft</i>-poly(acrylamide-<i>co</i>-acrylamide aniline tetramer) binder shows 701.2 mAh g^-1 after 200 cycles with excellent cyclic stability. This is significantly greater performance than that of commercial graphite electrodes.