Vanadium telluride nanoparticles on MWCNTs prepared by successive ionic layer adsorption and reaction for solid-state supercapacitor

Vanadium telluride anchored MWCNTs for advanced flexible solid-state symmetric supercapacitor correlated with density functional theory (DFT). • The V x Te y /MWCNTs electrode shows capacitance of 470 F/g in three-electrode system. • Solid-state symmetric supercapacitor with a voltage window of 2 V is fabricated. • The device exhibits high energy density (34.5 Wh/kg) and power density (1.8 kW/kg). • Excellent stability and mechanical flexibility show the practical aspect of device. • The electrochemical performance is supported by Density Functional Theory (DFT). Anchoring of vanadium telluride (V x Te y ) nanoparticles onto the exterior layer of multi-walled carbon nanotubes (MWCNTs) has been successfully employed at room temperature (300 K) as first report by using successive ionic layer adsorption and reaction (SILAR) to yield V x Te y /MWCNTs surface architecture. Mutualistic contribution from ion insertion/extraction introduced non-stoichiometric vanadium telluride with electric double-layer involved MWCNTs have been unified to enrich excellent electrochemical performance. Three-electrode system configured V x Te y /MWCNTs electrode yields 16-fold enhancement in specific capacitance compared to the bare MWCNTs electrode. Achieved performance forced us to construct flexible solid-state supercapacitor device (FSS-SC). Symmetric electrode embedded with PVA-LiClO 4 gel mediator harvests remarkable 2 V voltage window to gain 34.5 Wh/kg energy density and 0.7 kW/kg power density. Cycling over 10000 replications confirms the pronounced (82.5 %) stability of designed device and growing LED enables practical evidence; demonstrating its capacity as efficient energy storage device. Correlated density functional theory (DFT) has been manifested to confirm synergistic interactions between the V x Te y and MWCNTs, and a corresponding enhancement in the electron density at the Fermi level of V x Te y /MWCNTs describes the insight origin for enhanced supercapacitance.