Synergistic Effect of WN/Mo 2 C Embedded in Bioderived Carbon Nanofibers: A Rational Design of a Shuttle Inhibitor and an Electrocatalyst for Lithium-Sulfur Batteries.

To improve the innate shuttle effect and the sluggish redox kinetics of lithium-sulfur batteries, a composite made of a bimetallic compound embedded in nitrogen-doped carbon nanofibers (CNFs) is synthesized by employing biomass collagen fibers (CFs) as a structure template. Metal anions WO 4 2- and MoO 4 2- are grafted on plant polyphenol-modified CFs and then in situ converted into WN/Mo 2 C implanted in a matrix of CNFs (WMCNFs). The obtained WN/Mo 2 C is of quantum size and uniform distribution, exposing the active sites maximally. Further, the heterostructure of the bimetallic composite enables unique electronic interaction, thereby synergistically enhancing its adsorption capability toward soluble intermediates and activating its catalytic function for liquid-liquid and liquid-solid conversions. Combining these merits, when used as a separator modification material and a sulfur host simultaneously, the WMCNFs composite exhibits remarkable cycling stability with 91.45% capacity retention after 500 cycles at 2 C and also prominent rate performance of delivering 552.75 mAh g -1 at a current rate of 10 C. Meanwhile, the stable luminescence operation of LED lights powered by the assembled pouch cell demonstrates the application potential of this biomaterial-derived composite.