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

Abstract

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 SiOC 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.