Biomass Waste Chitosan-Derived Carbon with Si Doping Rich in C–O–Si Bonds for Boosting Lithium/Sodium-Ion Battery Anodes

The valorization of biomass waste into advanced electrode materials presents a promising pathway toward sustainable electrochemical energy storage. Herein, a silicon-doped carbon material (Si-CTS-Carbon) is synthesized from chitosan via an in situ reaction with silicon tetrachloride (SiCl4) and subsequent controlled pyrolysis. When evaluated as an anode for lithium-ion batteries (LIBs), Si-CTS-Carbon exhibits a high reversible capacity of 509.2 mAh g−1 with 99% capacity retention after 100 cycles at 0.05 A g−1. For sodium-ion battery (SIB) applications, it achieves a stable reversible capacity of 155.4 mAh g−1 under identical conditions. Structural and electrochemical analyses reveal that the robust C–O–Si covalent network effectively accommodates volume variation of silicon and enhances structural integrity during cycling. Furthermore, the hierarchically porous architecture shortens ion diffusion pathways, leading to improved Li+/Na+ transport kinetics. This work demonstrates a viable strategy for fabricating high-performance battery anodes by synergistically doping silicon into biomass-derived carbon, enabling practical biowaste valorization for energy storage.