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- Wenjing, Zhang, et al.
(författare)
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Electrospun nanofiber materials for energy and environmental applications
- 2019
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Ingår i: Energy Procedia. - : Elsevier. - 1876-6102.
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Konferensbidrag (refereegranskat)abstract
- Electrospinning is the one of the most versatile techniques to design nanofiber materials with numerous applications in the fields of energy conversion, catalytic chemistry, liquid and gas filtration.1 By electrospinning, complex structures can be designed from a rich variety of materials including polymers, metals, ceramics and composite, with the ability to control composition, morphology and secondary structure and tailor performance and functionality for specific applications. Moreover, with recent developments in the design of electrospinning equipment and availability of industrial-scale electrospinning technologies with production rates of several thousands of square meters per day new opportunities for electrospinning are imminent. With this, the advanced research on materials performed in our labs is getting closer to the commercialization of new products for applications in fields of energy and environment.An overview will be given on electrospinning activities at DTU Energy that address the sizable challenges in energy and environmental applications by electrospinning: 1. Electrospun perovskite oxide nanofiber electrode for use in solid oxide fuel cells. In this application, a (La0.6Sr0.4)0.99CoO3-δ cathode was shaped into 3-dimensional thin-film by so-gel assisted electrospinning method combined with calcination and sintering; 2. Electrospun nanofiber materials for gas adsorption. Both the advantages and challenges of using electrospun nanofiber materials will be discussed, in terms of electrochemical performance, surface area, packing efficiency and mechanical stability.
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| 3. |
- Younesi, Reza, et al.
(författare)
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Analysis of the Interphase on Carbon Black Formed in High Voltage Batteries
- 2015
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 162:7, s. A1289-A1296
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Tidskriftsartikel (refereegranskat)abstract
- Carbon black (CB) additives commonly used to increase the electrical conductivity of electrodes in Li-ion batteries are generally believed to be electrochemically inert additives in cathodes. Decomposition of electrolyte in the surface region of CB in Li-ion cells at high voltages up to 4.9 V is here studied using electrochemical measurements as well as structural and surface characterizations. LiPF6 and LiClO4 dissolved in ethylene carbonate:diethylene carbonate (1:1) were used as the electrolyte to study irreversible charge capacity of CB cathodes when cycled between 4.9 V and 2.5 V. Synchrotron-based soft X-ray photoelectron spectroscopy (SOXPES) results revealed spontaneous partial decomposition of the electrolytes on the CB electrode, without applying external current or voltage. Depth profile analysis of the electrolyte/cathode interphase indicated that the concentration of decomposed species is highest at the outermost surface of the CB. It is concluded that carboxylate and carbonate bonds (originating from solvent decomposition) and LiF (when LiPF6 was used) take part in the formation of the decomposed species. Electrochemical impedance spectroscopy measurements and transmission electron microscopy results, however, did not show formation of a dense surface layer on CB particles.
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| 4. |
- Zhang, Wenjing, et al.
(författare)
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Highly Structured Nanofiber Zeolite Materials for Biogas Upgrading
- 2020
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Ingår i: Energy Technology. - : John Wiley & Sons. - 2194-4296 .- 2194-4288. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Hierarchical zeolite composite nanofibers are designed using an electrospinning technique with post‐carbonization processing to form mechanically strong pellets for biogas upgrading. A ZSM‐5 nanopowder (zeolite) and a polyvinylpyrrolidone (PVP) polymer are electrospun to form ZSM/PVP composite nanofibers, which are transformed into a ZSM and carbon composite nanofiber (ZSM/C) by a two‐step heat treatment. The ZSM/C nanofibers show a 30.4% increase in Brunauer–Emmett–Teller (BET) surface area compared with the non‐structured ZSM‐5 nanopowder. Using ideal adsorbed solution theory, CO2‐over‐CH4 selectivity of 20 and CO2 uptake of 2.15 mmolg−1 at 293 K at 1 bar for ZSM/C nanofibers are obtained. For the efficient use of adsorbents in pressure swing adsorption operation, the nanofibers are structured into ZSM/C pellets that offer a maximum tensile strength of 6.46 MPa to withstand pressure swings. In the breakthrough tests, the CO2 uptake of the pellets reach 3.18 mmolg−1 at 293 K at 4 bar after 5 breakthrough adsorption–desorption cycles, with a much higher mass transfer coefficient of 1.24 ms−1 and CO2 uptake rate of 2.4 mg of CO2 g−1s−1, as compared with other structured zeolite adsorbents.
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