Biomass Waste Walnut Shells Derived Silicon-Doped Carbon Rich in C─O─Si Bonds for Energy Storage Devices: Lithium-Ion...

Biomass waste conversion to energy storage devices has gained significant attention. Here, we report a silicon-doped carbon material (Si─WH─Carbon) rich in C─O─Si bonds, synthesized from walnut shells (WH) and SiCl₄ via an in situ doping strategy. This sustainable approach yields a dual-functional material. As a lithium-ion battery anode, Si─WH─Carbon delivers a high discharge capacity of 604.8 mAh·g^-1 at 0.05 A·g^-1 over 100 cycles, which is higher than 460.3 mAh·g^-1 for the undoped carbon, owing to C─O─Si bonds that buffer silicon's volume expansion. Additionally, in supercapacitor applications, the material achieves a specific capacitance of 322.9 F·g^-1 at 0.5 A·g^-1. Silicon doping introduces polar Si─O─C groups that enhance wettability and promote efficient electrolyte-electrode contact, thereby improving charge transfer efficiency. This work offers a novel, cost-effective strategy for developing biomass-derived carbon materials with superior dual energy storage capabilities.