Polycarboxylate Functionalized Graphene/S Composite Cathodes and Modified Cathode-Facing Side Coated Separators for Advanced Lithium-Sulfur Batteries

Sulfur-hosting novel materials as a cathode for lithium-sulfur batteries are in the focus of many research to enhance the specific capacity and cycling stability. Herein, we developed composite cathodes consisting of polycarboxylate functionalized graphene (PC-FGF) doped with TiO₂ nanoparticles or poly1,5-diaminoanthraquinone (PDAAQ) and sulfur to enhance chemisorption property toward polysulfides. Additionally, PC-FGF/sulfur composite cathode functions as an efficient trapping site for polysulfides spices as well as contributes to facilitate electron and Li-ions movement toward or from the cathode. In the first experiment, the cell with sulfur incorporated TiO₂/PC-FGF cathode is assembled with three different cathode-facing side-coated glass fiber separators. At the second test, PDAAQ/PC-FGF cathode is assembled with the same separator materials as before. The best electrochemical performance observed was sulfur incorporated TiO₂/PC-FGF cathode with PDAAQ/PC-FGF-coated separator having a high discharge capacity of 1100 mAh g^{− 1} at 0.5 C after 100 cycles. It is found that the combination of TiO₂/PC-FGF/sulfur cathode and PDAAQ/PC-FCF separator could serve as promising cathode and separator material due to high cycling stability and rate capability for advanced Li-S batteries.