Polysulfides manipulation: Constructing g-C3N4 networks encapsulated into natural wood fibers for high-performance lithium–sulfur batteries

Lithium–sulfur batteries (LSBs) have become a dominant potential energy storage and conversion system because of their high theoretical specific capacity and energy density. Nevertheless, the shuttle effect and slow redox kinetics of polysulfides severely impede the wide application of LSBs. Herein, for polysulfide manipulation, a g–C3N4 network structure was creatively constructed in N, S co-doped carbonized wood fiber lumen (NSPCF@CN) using an etching induction strategy. Benefiting from the desirable characteristics endowed by the CN network structure, such as large specific surface area, special interfacial C–N–C bond, the composite with high activity improves the redox kinetics of polysulfides, alleviates the shuttle effect, and reduces the volume change during charging and discharging. As expected, the cathode made from NSPCF@CN–10 and sulfur composite (NSPCF@CN–10/S) possesses a remarkable specific capacity of 1590.8 mAh g−1 at 0.5 C, and a high-rate capability of 976.9 mAh g−1 at 2.0 C. More interestingly, a reversible capacity as high as 781 mAh g−1 over 1000 cycles at 1.0 C is achieved. Density functional theory calculations reveal that the synergistic effect of N, S co-doping and CN network structure can effectively improve the adsorption capacity of polysulfide. This approach of constructing the network structure in natural wood fiber lumen provides a new vision for addressing the complex problems associated with LSBs.