W ₁₈ O ₄₉ nanowires assembled on carbon felt for application to supercapacitors

For supercapacitor applications, W ₁₈ O ₄₉ nanowires have been extensively grown on graphitic carbon felt using a facile solvothermal method. The diameter and length of the nanowires are about 7 and 300 nm, respectively. The nanowires consist of monoclinic W ₁₈ O ₄₉ grown along the [010] direction, as shown by TEM and XRD analyses. The W ₁₈ O ₄₉ nanowires, assembled on carbon felt, exhibit a high capacity of 588.33 F/g at a current density of 1 A/g together with an excellent cycle performance, and a low internal resistance during the electrochemical tests. This outstanding performance may originate from the three-dimensional porous nanostructure of these W ₁₈ O ₄₉ nanowires, which leads to a reduction in the resistance and fast reaction kinetics due to the high specific surface area and electrolyte accessibility. Furthermore, sufficient oxygen deficiencies of the substoichiometric tungsten oxide can also contribute to the electrochemical activity, which can be confirmed by comparison of CV and EIS data with WO ₃ nanowires.