Lignin-Based Polymer Networks Enabled N, S Co-Doped Defect-Rich Hierarchically Porous Carbon Anode for Long-Cycle Li-Ion Batteries

The commercial graphitic anode with low specific capacity and serious lithium dendrite growth has limited further improvements of Li-ion batteries (LIBs). Here, we report a hierarchical porous hard carbon with N, S codoping (LSCF) that is synthesized using trifunctional sodium lignosulfonate (LS) from the pulp waste as the self-sacrificing template, carbon source, sulfur source, and natural chitosan as both the carbon source and nitrogen source. The strong hydrogen-bond interaction between the LS and chitosan enabled the robust stability of the carbon framework. And the self-template of sulfates and carbonates from LS enabled the formation of the hierarchical porous structure. First-principles calculations indicate that the hierarchical porous LSCF carbon with heteroatom doping has a lower diffusion barrier of Li+ and a higher electron conductivity. As an anode for LIBs, the LSCF delivers the specific capacity of 350 mAh g(-1) at 100 mA g(-1) with 85% retention after 1000 cycles. This work offers a one-step and low-cost method to fabricate the porous hard carbon anode for LIBs with dual-atom doping based on green natural polymers.