Intercalation of alkylamines in layered MoO3 and in situ carbonization for a high-performance asymmetric supercapacitor

Abstract

MoO₃/C nanocomposites are synthesized by first intercalating alkylamines into layered MoO₃ and then in situ carbonization at high temperature. The possible arrangements of alkylamines in the interlayers of MoO₃ and the interaction between the inorganic host and the organic guest are discussed. The resulting MoO₃/C nanocomposite with a high degree of graphitization exhibits a high specific capacitance of 335 F g⁻¹ at a current density of 1 A g⁻¹ and an excellent rate performance (70% capacitance retained 70% capacitance retained from 1 A g⁻¹ to 10 A g⁻¹). In addition, the obtained nanocomposite can be matched well with expanded graphite to maximize the specific capacitance and also to extend the potential window, giving rise to an increased energy density of the cell. The assembled MoO₃/C//expanded graphite asymmetric supercapacitor can be cycled reversibly between 0 and 1.6 V with a specific capacitance of 88 F g⁻¹ at 1 A g⁻¹ and an energy density of 31.3 W h kg⁻¹ at a power density of 838.4 W kg⁻¹. Moreover, this supercapacitor exhibits a good cycling behavior with no more than 13.5% capacitance loss after 5000 cycles at 1 A g⁻¹. The excellent performance is mainly attributed to two aspects. On the one hand, opening up MoO₃ layers with conductive carbon can provide more redox sites for Faradaic reaction and promote transportation of electrons. On the other hand, MoO₃ and intercalated carbon layers form a sandwich-type hybrid nanostructure, which facilitates the penetration and diffusion of electrolyte ions. This work may pave the way for fabricating active electrode materials for high performance energy storage devices through intercalation and in situ carbonization.