In situ generated iron silicate on porous carbon derived from rice husks for high-performance supercapacitor and full utilization of resource

The high-performance Fe₂SiO₄ electrode material is prepared for supercapacitor through KHCO₃ activating the carbon and simultaneously etching SiO₂ derived from rice husks and hydrothermal treatment process. The prepared electrode material has a 3D hierarchical interconnected pore structure, which provides abundant channels and shorter diffusion pathways for electrons and ions. The SiO₂ of rice husks is converted into Fe₂SiO₄ by loading Fe element, which provides the larger specific capacitance. The Si[sbnd]O[sbnd]C bond in the cell wall of rice husks can reduce the electron transfer barrier at the heterogeneous interface. The single electrode shows the specific capacitance of 534.345F·g⁻¹ at the current density of 0.5 A·g⁻¹, surpassing the silicate materials previously studied. The assembled solid-state asymmetric supercapacitor device of FeSi//activated carbon has a large energy density and power density, reaching 0.69 Wh·m⁻² at 13.50 W·m⁻². Additionally, the device presents good cycle performance for 8000 cycles with 85% retention. This work provides a new strategy for the green application of rice husks and promotes the development of low-cost electrode materials for supercapacitors.