Carbon encapsulation of silicon via lignosulfonate/chitosan electrostatic assembly and glucose-coating for enhanced lithium-ion battery anodes

Silicon (Si) is regarded as one of the most prospective lithium-storage materials owing to its large theoretical specific capacity (4200 mAh/g) and low operating potential. However, during lithiation/delithiation processes, the tremendous volume change (~ 300%) and poor conductivity of Si materials restrict their large-scale application in the field of electrodes. Herein, a novel encapsulating strategy was proposed to prepare silicon/carbon composites (650-4-glu). The self-assembly process, driven by electrostatic interaction between lignosulfonate and chitosan, initially enwrapped silicon nanoparticles. Furthermore, glucose was introduced through simple grinding with the lignin-Si-chitosan assembly. After carbonization, physicochemical characterization revealed that the carbon framework derived from lignin-chitosan largely coated silicon and glucose-derived carbon served as a supplementary phase to enhance the encapsulation effect. The formation of Si-O-C linkages between carbon and silicon tightly bound the silicon particles, which was crucial for improving cycling stability and rate performance. Sample 650-4-glu exhibited an excellent specific capacity, retaining 734.3 mAh/g after 200 cycles at 0.5 A/g and 584.1 mAh/g after 500 cycles at 1.0 A/g. This work demonstrated a sustainable and effective approach for utilizing lignosulfonate, a byproduct in the papermaking industry, in high-performance lithium-ion battery electrodes.