Sandwich-like honeycomb Co2SiO4/rGO/honeycomb Co2SiO4 structures with enhanced electrochemical properties for high-performance hybrid supercapacitor

Abstract Recent studies demonstrate that cobalt silicate-based materials are considered as the potential electrode materials for supercapacitors (SCs). However, improving the conductivity of Co2SiO4 remains a pressing priority. Herein, the sandwich-like honeycomb Co2SiO4/rGO/honeycomb Co2SiO4 structures are developed to improve the electrochemical capabilities of Co2SiO4 by using the sandwich-like GO/SiO2 as template and with a moderate hydrothermal method. Co2SiO4 nanosheets on the surface of rGO are interconnected to form the 3D honeycomb-like structures. This strategy, “Two for one” construction, means that we put the two-phase (Co2SiO4 and rGO) into one-phase (Co2SiO4/rGO integrated composite) to avoid the low electronic transmission problem of the traditional two-phase hybrid method. The s-rGO/Co2SiO4 electrode exhibits the specific capacitance of 429 F g−1 at 0.5 A g−1, which is superior to the capacitance of Co2SiO4 and rGO + Co2SiO4. The s-rGO/Co2SiO4//AC HSC delivers the areal capacitances of 651 mF cm−2 at 1 mA cm−2, and powers the bulb more than 300 s, which is strongly related to the energized capacitance s-rGO/Co2SiO4. This work not only proves that the s-rGO/Co2SiO4 can improve the electrochemical properties of Co2SiO4, but also provides a strategy for the synthesis of metal silicates/rGO/metal silicates sandwich-like structures with enhanced electrochemical performances for energy storage and conversion.