Enhanced performance of supercapacitors by constructing a “mini parallel-plate capacitor” in an electrode with high dielectric constant materials

Abstract

As a class of highly stable materials, the application of high dielectric constant materials in the field of energy is hampered by their low electrical conductivity and poor energy storage capacity. To solve these inherent limitations, herein, a useful strategy was developed to improve the energy storage performance of high dielectric constant electrode materials by combining the characteristics of parallel-plate capacitors. A novel sandwich structure with a carbon fiber/metal oxide/metal oxynitride layer (CMM) were used to construct a “mini parallel-plate capacitor” in the electrode, and the capacitance was remarkably enhanced. In this structure, the metal oxides (SnO₂, Fe₂O₃, VO₂, and TiO₂) with different dielectric constants worked as the dielectric, while the carbon fiber and the metal oxynitride layer worked as the plate electrodes. As expected, the dielectric constant of the metal oxides was directly proportional to the capacitance increase. Specifically, the capacitance of TiO₂ was enhanced up to 11.75 times after the construction of this structure. Moreover, the relevant mechanism of the enhanced capacitance was investigated by the parallel-plate capacitor model. This novel strategy can provide new ideas for the study of high dielectric constant materials in the field of energy storage.