A novel SWCNT-polyoxometalate nanohybrid material as an electrode for electrochemical supercapacitors

Abstract

A novel nanohybrid material that combines single-walled carbon nanotubes (SWCNTs) with a polyoxometalate (TBA)₅[PV^V₂Mo^VI₁₀O₄₀] (TBA-PV₂Mo₁₀, TBA: [(CH₃(CH₂)₃)₄N]⁺, tetra-n-butyl ammonium) is investigated for the first time as an electrode material for supercapacitors (SCs) in this study. The SWCNT-TBA-PV₂Mo₁₀ material has been prepared by a simple solution method which electrostatically attaches anionic [PV₂Mo₁₀O₄₀]⁵⁻ anions with organic TBA cations on the SWCNTs. The electrochemical performance of SWCNT-TBA-PV₂Mo₁₀ electrodes is studied in an acidic aqueous electrolyte (1 M H₂SO₄) by galvanostatic charge/discharge and cyclic voltammetry. In this SWCNT-TBA-PV₂Mo₁₀ nanohybrid material, TBA-PV₂Mo₁₀ provides redox activity while benefiting from the high electrical conductivity and high double-layer capacitance of the SWCNTs that improve both energy and power density. An assembled SWCNT-TBA-PV₂Mo₁₀ symmetric SC exhibits a 39% higher specific capacitance as compared to a symmetric SC employing only SWCNTs as electrode materials. Furthermore, the SWCNT-TBA-PV₂Mo₁₀ SC exhibits excellent cycling stability, retaining 95% of its specific capacitance after 6500 cycles.