Biowaste ligninsulfonate functionalized cathode of lithium-sulfur battery for immobilization and catalyzation of...

Lithium‑sulfur batteries (LSBs) have been appealing an increasing attention in last ten years with the overwhelming advantages of greatly higher theoretical energy density and specific capacity in comparison with traditional Li-ion batteries (LIBs). However, the commercial application of LSBs still confronts some intractable challenges, of which the shuttle effect and sluggish redox kinetics are reckoned as the most serious obstacles. Incorporation of polar sulfonate groups into cathode has been believed as an effective avenue to immobilize polysulfides and thus enables to alleviate the shuttle effect. Moreover, those grafted sulfonate groups create some more Li⁺ high-speed pathways and meanwhile catalyze the redox conversion of polysulfides, which as a consequence greatly expedites the redox kinetics of LSB. To circumvent the hazardous reagents and complicated procedures for the introduction of sulfonate groups, herein the biomacromolecule ligninsulfonate (LS), a high-yield biowaste from the classical sulfite pulping industry, is employed to host elemental S followed by blending with conductive carbon nanotubes (CNTs). After replacing by Li⁺ ions, the as-prepared S@LiLS/CNTs cathode exhibits high specific capacity (1265 mAh g^-1 at 0.2C), superior rate capability (629 mAh g^-1 at 5C), and stable cyclability (70 % capacity retention after 1000 cycles). This work paves the avenue of exploiting waste biological macromolecules in high-performance electrodes of advanced energy storage systems.