Metalized Polyacrylates\nas Efficient Binder for a\nSulfurized Polyacrylonitrile/Polydopamine Active Material in Sulfur\nCathodes for Room Temperature Sodium–Sulfur Batteries

Abstract

Promising binder systems with special chemical and mechanical\nfunctions\nare under extensive exploration to cope with serious volume change\nand harmful shuttle effect occurring during charge/discharge cycles\nof a sulfur cathode in sodium–sulfur (Na–S) batteries.\nIn this aspect, sulfurized polyacrylonitrile (SPAN)/polydopamine (PDA)\nactive materials are combined with different metalized polyacrylates\n(MPAAs) to result in a SPAN/PDA/MPAA binder system with peculiar morphology\nand superior mechanical and interfacial strengths. As the outer layer\nof SPAN/PDA/MPAA, MPAA can extend its long chains to interact with\ncathode components and, moreover, metal ions of MPAA can participate\nin the beneficial electron transport process. The results suggest\nthat stability and electrochemical performance of the sulfur cathodes\ndepend on the applied metal ions, which become better and better as\nthe valence of metal ions change from mono (Na), di (Ca), and tri\n(Fe) to tetra (Ti). Cathode derived from SPAN/PDA/titanium polyacrylate\n(TiPAA) shows the best stability and electrochemical performance,\nexhibiting a rather high specific capacity of 1438 mAh g^–1 at 0.2 C for 100 cycles and 1271 mAh g^–1 at 1\nC for 300 cycles. Hopefully, this study can provide a foundation on\nhow to use different metal ions to manipulate the electrochemical\nperformance of sulfur cathode in Na–S batteries.