A New Conjugated Porous Polymer with Covalently Linked Polysulfide as Cathode Material for High-Rate Capacity and High Coulombic Efficiency Lithium–Sulfur Batteries

Lithium–sulfur batteries show high specific capacity and environmental friendliness. However, the shuttling effect and volumetric expansion of sulfur electrodes often lead to low Coulombic efficiency and C-rate capacity for the lithium–sulfur battery. In this work, we develop a novel sulfur-rich triazine-trithiophene-triacetylenicbenzene conjugated porous polymer cathode material (TBP-S) by a covalent linkage between a conjugated porous polymer and sulfur. The as-prepared material shows combinative features of the functions of supports, conductors, and adsorbents, resulting in the effective suppression of the shuttling effect. Specifically, the cell based on the TBP-80S cathode material shows outstanding C-rate capacity at the current of 5C (discharge capacity of 756 mAh g–1). Furthermore, the Coulombic efficiency of the cell retains up to 99.6% after 400 cycles at 0.5C. These results demonstrate that this type of sulfur-rich conjugated porous polymer has a great potential as excellent cathode material for a lithium–sulfur battery with high Coulombic efficiency and superior C-rate capacity.