Abstract
In this work, we report the synthesis of hydrated and non-crystalline WO3 flakes (WO3−x) via an environmentally friendly and facile water-based strategy. This method is described, in the literature, as exfoliation, however, based on the results obtained, we cannot say unequivocally that we have obtained an exfoliated material. Nevertheless, the proposed modification procedure clearly affects the morphology of WO3 and leads to loss of crystallinity of the material. TEM techniques confirmed that the process leads to the formation of WO3 flakes of a few nanometers in thickness. X-ray diffractograms affirmed the poor crystallinity of the flakes, while spectroscopic methods showed that the materials after exfoliation were abundant with the surface groups. The thin film of hydrated and non-crystalline WO3 exhibits a seven times higher specific capacitance (Cs) in an aqueous electrolyte than bulk WO3 and shows an outstanding long-term cycling stability with a capacitance retention of 92% after 1000 chronopotentiometric cycles in the three-electrode system. In the two-electrode system, hydrated WO3−x shows a Cs of 122 F g−1 at a current density of 0.5 A g−1. The developed supercapacitor shows an energy density of 60 Whkg−1 and power density of 803 Wkg−1 with a decrease of 16% in Csp after 10,000 cycles. On the other hand, WO3−x is characterized by inferior properties as an anode material in lithium-ion batteries compared to bulk WO3. Lithium ions intercalate into a WO3 crystal framework and occupy trigonal cavity sites during the electrochemical polarization. If there is no regular layer structure, as in the case of the hydrated and non-crystalline WO3, the insertion of lithium ions between WO3 layers is not possible. Thus, in the case of a non-aqueous electrolyte, the specific capacity of the hydrated and non-crystalline WO3 electrode material is much lower in comparison with the specific capacity of the bulk WO3-based anode material.
Highlights
The increase in global energy consumption, caused by the rapid increase in population, forces the production of energy storage and energy conversion systems on a larger scale
The obtained yellow powder of WO3−x nanoflakes was dried at 80 ◦ C for 24 h and was used for the material characterization (TEM, SEM, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), FTiR), as well as for the electrode preparation for the electrochemical measurements performed in a non-aqueous electrolyte
The first two maxima may of Lix Wx (V) W(VI) x−1 O3, while the last maximum might be attributed to the lithium ion intercalation confirm the formation of LixWx(V)W(VI)x−1O3, while the last maximum might be attributed to the lithium into carbon black, which is one of the components of the electrode material
Summary
The increase in global energy consumption, caused by the rapid increase in population, forces the production of energy storage and energy conversion systems on a larger scale. Despite the various energy storage mechanisms, one can assume that transition metal oxides may be successfully adapted as electrode materials for supercapacitors as well as for batteries (for example, Co3 O4 , MnOx , TiO2 ) [5,6,7]. In the case of metal oxides, the exfoliation usually involves sonication in a surfactant solution and ion or polymer intercalation [38,39,40] The application of the latter method leads to obtaining single layers in a crystalline form, possessing the promising properties and gives large quantities of a dispersed nanomaterial.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
