Triple Cross-Linked Network Derived from Xanthan Gum/Sodium Poly(acrylic acid)/Metal Ion as a Functional Binder of the Sulfur Cathode in Lithium–Sulfur Batteries

The volume change and shuttle effect of sulfur are detrimental to the stability and electrochemical performance of the sulfur cathode in lithium–sulfur (Li–S) batteries. In this study, a triple cross-linked (TC) network system, containing a chemical covalent bond, physical hydrogen bond (H bond), and ionic bond, was designed and fabricated to deal with the shuttle effect and volume expansion of the sulfur cathode. The TC system was derived from a facile cross-linking reaction of xanthan gum, sodium polyacrylate, and Zn²⁺ metal ions at elevated temperature. The densely packed cross-linked network structure in the TC system provides the desired mechanical robustness for sustaining the volume change of sulfur during cycling, whereas the zinc ions in the TC system preferably react with lithium polysulfides to limit the detrimental shuttle effect. Thus, the corresponding TC binder constructed an efficient sulfur cathode with superior stability and excellent capacitance retention of 892 mAh g^–1 at 0.2 C for 100 cycles and 770 mAh g^–1 at 1 C for 300 cycles.