Abstract
Herein, a one‐step protocol for synthesizing freestanding 20 μm thick cellulose paper electrodes composed of V2O5 ⋅ H2O nanosheets (VOx), carbon nanotubes (CNTs), and Cladophora cellulose (CC) is reported. In 1.0 m Na2SO4, the VOx–CNT–CC electrodes deliver capacities of about 200 and 50 C g−1 at scan rates of 20 and 500 mV s−1, respectively. The obtained capacities are compared with the theoretical capacities and are discussed based on the electrochemical reactions and the mass loadings of the electrodes. It is shown that the capacities are diffusion rate limited and, consequently, depend on the distribution and thickness of the V2O5 ⋅ H2O nanosheets, whereas the long‐term cycling stabilities depend on vanadium species dissolving in the electrolyte. The electrodes feature high mass loadings (2 mg cm−2), good rate performances (25% capacity retention at 500 mV s−1), and capacity retentions of 85% after 8000 cycles. A symmetric VOx–CNT–CC energy storage device with a potential window of about 1 V exhibits a capacity of 40 C g−1 at a scan rate of 2 mV s−1.
Highlights
A one-step protocol for synthesizing freestanding 20 μm thick cellulose anisms
Given amounts of V2O5 ⋅ nH2O, carbon nanotubes (CNTs), and Cladophora cellulose (CC) in the weight ratios of 7:2:1 were dispersed by sonication in a 3:1 water–ethanol mixture
The results showed that the capacity retention of VOx–CNT–CC electrodes varied between 85% and 46% after 8000 cycles
Summary
The V2O5 ⋅ H2O nanosheets were prepared using water-based exfoliation of V2O5 in the presence of oxalic acid, and the chemical, thermal, and structural analyses of the obtained V2O5 ⋅ H2O nanosheets have been described elsewhere.[11,57] The as-prepared V2O5 ⋅ H2O is composed of three to six layers and contains about 20% V4þ as indicated by previous high resolution transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), Nuclear magnetic resonance (NMR), and X-ray absorption near-edge structure (XANES) data.[12,13,20] previous findings indicate that there is approximately one water molecule per V2O5 unit at room temperature.[20]. The X-ray diffraction (XRD) pattern of the VOx–CNT–CC paper (see Figure S1a, Supporting Information) shows that the structure of the V2O5 ⋅ H2O within the cellulose paper electrodes is analogous to that of pristine V2O5 ⋅ H2O. The side view displays that the thickness of the cellulose paper electrode is about 20 μm, whereas the top view indicates that the V2O5 ⋅ H2O is distributed within the randomly oriented CNT–CC matrix. The energy-dispersive X-ray (EDX) mapping likewise indicates an even distribution of V, O, and C Supporting Information), further supporting a uniform distribution of V2O5 ⋅ H2O within the CNT–CC matrix This finding is, challenged by the results of the electrochemical characterization, which indicates inhomogeneous depth distributions of V2O5 ⋅ H2O in the electrodes (see below). The latter indicates that some of the V2O5 ⋅ H2O was less electrochemically accessible even though a homogeneous distribution was seen in the EDX mapping results
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.
