Layer by layer assembly of ultrathin V2O5 anchored MWCNTs and graphene on textile fabrics for fabrication of high energy density flexible supercapacitor electrodes

Abstract

Among transition metal oxides, vanadium oxides have received relatively modest attention for supercapacitor applications. Yet, this material is abundant, relatively inexpensive and offer several oxidation states which can provide a broad range of redox reactions suitable for supercapacitor operation. Electrochemical supercapacitors based on nanostructured vanadium oxide (V₂O₅) suffer from relatively low energy densities as they have low surface area and poor electrical conductivities. To overcome these problems, we developed a layer by layer assembly (LBL) technique in which a graphene layer was alternatively inserted between MWCNT films coated with ultrathin (3 nm) V₂O₅. The insertion of a conductive spacer of graphene between the MWCNT films coated with V₂O₅ not only prevents agglomeration between the MWCNT films but also substantially enhances the specific capacitance by 67%, to as high as ∼2590 F g⁻¹. Furthermore, the LBL assembled multilayer supercapacitor electrodes exhibited an excellent cycling performance of >97%, capacitance retention over 5000 cycles and a high energy density of 96 W h kg⁻¹ at a power density of 800 W kg⁻¹. Our approach clearly offers an exciting opportunity for enhancing the device performance of metal oxide-based electrochemical supercapacitors suitable for next-generation flexible energy storage devices by employing a facile LBL assembly technique.