| 1. |
- Andersson, Claes-Henrik, 1980-, et al.
(författare)
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Synthesis and characterization of a ferrocene-linked bis-fullerene[60] dumbbell
- 2012
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Ingår i: Dalton Transactions. - 1477-9226 .- 1477-9234. ; 41:8, s. 2374-2381
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Tidskriftsartikel (refereegranskat)abstract
- A new [60]fullerene dumbbell consisting of two fulleropyrrolidines connected to a central ferrocene unit by amide linkages has been prepared and fully characterized by elemental analysis, 1H NMR, UV/Vis, fluorescence and mass spectrometry. The electrochemical properties as determined by cyclic voltammetry show ground state electronic communication between the ferrocene and the fullerene units. In addition, the preparaton of a ferrocene building block for an alternative linking approach is presented.
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| 2. |
- Asfaw, Habtom Desta, 1986-, et al.
(författare)
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Over-Stoichiometric NbO2 Nanoparticles for a High Energy and Power Density Lithium Microbattery
- 2017
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Ingår i: ChemNanoMat. - : Wiley. - 2199-692X. ; 3:9, s. 646-655
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Tidskriftsartikel (refereegranskat)abstract
- Effective utilization of active materials in microbatteries can be enhanced by rational design of the electrodes. There is an increasing trend of using 3D electrodes that are coated in nanosized active materials to boost both energy and power densities. This article focuses on the fabrication of 3D electrodes based on monolithic carbon foams coated in over-stoichiometric NbO2 nanoparticles. The electrodes exhibit remarkable energy and power densities at various current densities when tested in lithium microbatteries. An areal capacity of around 0.7mAhcm(-2) and energy density up to 45mWhcm(-3) have been achieved. More than half of the areal capacity can be accessed at a current density of about 11mAcm(-2), with the corresponding energy and power densities being 21mWhcm(-3) and 1349mWcm(-3). These values are comparable to those of microsupercapacitors containing carbon and MnO2 nanomaterials. Furthermore, the electrochemical reversibility improves progressively upon cycling along with substantial increase in the charge transfer kinetics of the electrode. Based on impedance analyses almost a fourfold decrease in the charge transfer resistance has been observed over 25 cycles. Such enhancement of the electronic properties of NbO2 can account for the high electrochemical rate performance of the 3D electrodes.
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| 3. |
- Asfaw, Habtom Desta, Dr. 1986-, et al.
(författare)
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Tailoring the Microstructure and Electrochemical Performance of 3D Microbattery Electrodes Based on Carbon Foams
- 2019
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Ingår i: Energy Technology. - : Wiley. - 2194-4288 .- 2194-4296.
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Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional (3D) carbon electrodes with suitable microstructural features and stable electrochemical performance are required for practical applications in 3D lithium (Li)-ion batteries. Herein, the optimization of the microstructures and electrochemical performances of carbon electrodes derived from emulsion-templated polymer foams are dealt with. Exploiting the rheological properties of the emulsion precursors, carbon foams with variable void sizes and specific surface areas are obtained. Carbon foams with an average void size of around 3.8 mu m are produced, and improvements are observed both in the coulombic efficiency and the cyclability of the carbon foam electrodes synthesized at 2200 degrees C. A stable areal capacity of up to 1.22 mAh cm(-2) (108 mAh g(-1)) is achieved at a current density of 50 mu A cm(-2). In addition, the areal capacity remains almost unaltered, i.e., 1.03 mAh cm(-2) (91 mAh g(-1)), although the cycling current density increases to 500 mu A cm(-2) indicating that the materials are promising for power demanding applications.
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| 4. |
- Böhme, Solveig, 1987-, et al.
(författare)
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Overlapping and rate controlling electrochemical reactions for tin(IV) oxide electrodes in lithiu-ion batteries
- 2017
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Ingår i: Journal of Electroanalytical Chemistry. - 0022-0728 .- 1873-2569. ; 797, s. 47-60
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Tidskriftsartikel (refereegranskat)abstract
- The results of this extensive electrochemical study of the electrochemical reactions of SnO2 electrodes in lithium-ion batteries demonstrate that the different reduction and oxidation reactions overlap significantly during the cycling and that the rates of the redox reactions are limited by the mass transport through the layers of oxidation or reduction products formed on the electrodes. The experiments, which were carried out in the absence and presence of the lithium alloy reactions, show that the capacity losses seen on the first cycles mainly can be explained by an incomplete oxidation of the lithium tin alloy and an incomplete reformation of SnO2. The latter can be explained by the formation of thin tin oxide layers (i.e., SnO and SnO2), protecting the remaining tin, as the oxidation current then becomes limited by the Li+ diffusion rate though these layers. The results, also show that the first cycle SnO2 reduction was incomplete for the about 20 μm thick electrodes containing 1 to 6 μm large SnO2 particles. This can be ascribed to the formation of a layer of tin and Li2O (protecting the remaining SnO2) during the reduction process. Although the regeneration of the SnO2 always was slower than the reduction of the SnO2, the results clearly show that the SnO2 conversion reaction is far from irreversible, particularly at low scan rates and increased temperatures. Electrochemical cycling at 60 °C hence gave rise to increased capacities, but also a faster capacity loss, compared to at room temperature. These new findings indicate that a full utilization of SnO2 based electrodes at a given cycling rate only can be reached with sufficiently small particles since the allowed particle size is given by the time available for the mass transport through the formed surface layers. The present results consequently provide important insights into the phenomena limiting the use of SnO2 electrodes in lithium-ion batteries.
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| 5. |
- Chien, Yu-Chuan, 1990-, et al.
(författare)
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Cellulose Separators With Integrated Carbon Nanotube Interlayers for Lithium-Sulfur Batteries : An Investigation into the Complex Interplay between Cell Components
- 2019
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 166:14, s. A3235-A3241
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Tidskriftsartikel (refereegranskat)abstract
- This work aims to address two major roadblocks in the development of lithium-sulfur (Li-S) batteries: the inefficient deposition of Li on the metallic Li electrode and the parasitic "polysulfide redox shuttle". These roadblocks are here approached, respectively, by the combination of a cellulose separator with a cathode-facing conductive porous carbon interlayer, based on their previously reported individual benefits. Both approaches result in significant improvements in cycle life in test cells with positive electrodes with practically relevant specifications. Despite the substantially prolonged cycle life, the combination of the interlayer and cellulose separator generates an increase in polysulfide shuttle current, leading to greatly reduced Coulombic efficiency. Based on XPS analyses, the latter is ascribed to a change in the composition of the solid electrolyte interphase (SEI) on the Li electrode. At the same time, the rate of electrolyte decomposition is found to be lower in cells with cellulose-based separators, which corroborates the observation of longer cycle life. These seemingly contradictory and counterintuitive observations demonstrate the complicated interactions between the cell components in the Li-S system and how strategies aiming to mitigate one unwanted process may exacerbate another. This study demonstrates the value of a holistic approach to the development of Li-S chemistry.
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| 6. |
- Chien, Yu-Chuan, 1990-, et al.
(författare)
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Electrochemical Analysis of Modified Separators for Li-S Batteries
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The lithium-sulfur system is one of the potential energy storage technologies of the next generation due to the high theoretical specific capacity (1672 mAh/g), abundance and nontoxicity of sulfur [1]. However, there are still challenges yet to be overcome, one of which is the ‘polysulfide shuttle’ [1]. In order to address this issue, several modifications of the separators have been proposed. For example, longer cycle life, higher Coulombic efficiency and higher specific capacities have been reported with metal oxide coatings [2] and conductive interlayers [3,4] on the separators. Performance improvements in one or more of these properties have been ascribed to a suppression of polysulfide transport across the separator, even though this has not always been correlated with the difference in electrochemistry. In this work, the Intermittent Current Interruption (ICI) method [5] is applied to monitor the evolution of internal resistance of Li-S cells with different separators during repeated charge and discharge. Cells with different separators exhibit significant differences in resistance as a function of state-of-charge in the initial cycles, as shown in the figure. Complemented by self-discharge tests and impedance spectroscopy at selected states of charge, the roles of the interlayers in the system can be further interpreted electrochemically. This work aims to associate the electrochemical properties of the interlayers to their corresponding microstructural counterparts, which can in turn facilitate further development of the interlayer materials. Figure: Internal resistance of cells vs specific charge for Li-S cells with different separators (Zero charge indicates the fully charged state.) for the 2nd, 5th and 10th cycles at C/10 rate. References:[1] S. Urbonaite, T. Poux, P. Novák, Adv. Energy Mater. 5 (2015) 1–20.[2] Z. Zhang, Y. Lai, Z. Zhang, K. Zhang, J. Li, Electrochim. Acta 129 (2014) 55–61.[3] H. Yao, K. Yan, W. Li, G. Zheng, D. Kong, Z.W. Seh, V.K. Narasimhan, Z. Liang, Y. Cui, Energy Environ. Sci. 7 (2014) 3381–3390.[4] J. Balach, T. Jaumann, M. Klose, S. Oswald, J. Eckert, L. Giebeler, Adv. Funct. Mater. 25 (2015) 5285–5291.[5] M.J. Lacey, K. Edström, D. Brandell, Chem. Commun. 51 (2015) 16502–16505.
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| 7. |
- Colbin, Lars Olow Simon, et al.
(författare)
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Anodic dissolution of aluminum in non-aqueous electrolyte solutions for sodium-ion batteries
- 2023
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Ingår i: Energy Advances. - : Royal Society of Chemistry. - 2753-1457. ; 3:1, s. 143-
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Tidskriftsartikel (refereegranskat)abstract
- Anodic dissolution of aluminum (commonly called aluminum corrosion) is a potential issue in sodium-ion batteries. Herein, it is demonstrated how different sodium-ion battery electrolyte solutions affect this phenomenon. The type of electrolyte was critical for the presence of anodic dissolution, while the solvent appeared to alter the dissolution process.
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| 8. |
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| 9. |
- Etman, Ahmed, et al.
(författare)
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On the Capacities of Freestanding Vanadium Pentoxide-Carbon Nanotube-Nanocellulose Paper Electrodes for Charge Storage Applications
- 2020
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Ingår i: ENERGY TECHNOLOGY. - : WILEY-V C H VERLAG GMBH. - 2194-4288 .- 2194-4296. ; 8:12
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Tidskriftsartikel (refereegranskat)abstract
- Herein, a one-step protocol for synthesizing freestanding 20 mu m 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).
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| 10. |
- Etman, Ahmed, et al.
(författare)
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One-pot Synthesis of MoO3-x Nanosheets for Supercapacitor Applications
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Molybdenum oxide nanosheets are interesting materials for energy storage, catalysis, and gas sensor applications.1 However, they are traditionally prepared via a variety of approaches which require the use of high temperature or organic solvents.2,3 Herein, we report the synthesis of MoO3-x nanosheets (where x denotes oxygen vacancy) via a one-step water based exfoliation strategy using bulk molybdenum oxides precursors.4 Scanning and transmission electron microscopy show that the MoO3-x has a typical nanosheet morphology with a few nanometer thickness. The MoO3-x nanosheets display localized surface plasmon resonance (LSPR), which can be enhanced by modifying the morphology and the amount of oxygen vacancies (x) using chemical and/or photochemical treatments.The aqueous suspension of the MoO3-x nanosheets was drop-cast onto carbon paper and this material was then used as binder free electrodes for supercapacitor applications. The electrodes showed promising performance regarding capacitance and rate capability in acidified sodium sulphate solutions. The facile green synthesis of MoO3-x nanosheets coupled with their significant photochemical and electrochemical properties pave the way for the use of the nanosheets in a variety of applications.References:(1) de Castro, I. A.; Datta, R. S.; Ou, J. Z.; Castellanos-Gomez, A.; Sriram, S.; Daeneke, T.; Kalantar-zadeh, K. Molybdenum Oxides - From Fundamentals to Functionality. Adv. Mater. 2017, 29 (40), 1701619.(2) Xiao, X.; Song, H.; Lin, S.; Zhou, Y.; Zhan, X.; Hu, Z.; Zhang, Q.; Sun, J.; Yang, B.; Li, T.; Jiao, L.; Zhou, J.; Tang, J.; Gogotsi, Y. Scalable Salt-Templated Synthesis of Two-Dimensional Transition Metal Oxides. Nat. Commun. 2016, 7, 11296.(3) Alsaif, M. M. Y. A.; Field, M. R.; Daeneke, T.; Chrimes, A. F.; Zhang, W.; Carey, B. J.; Berean, K. J.; Walia, S.; van Embden, J.; Zhang, B.; Latham, K.; Kalantar-zadeh, K.; Ou, J. Z. Exfoliation Solvent Dependent Plasmon Resonances in Two-Dimensional Sub-Stoichiometric Molybdenum Oxide Nanoflakes. ACS Appl. Mater. Interfaces 2016, 8 (5), 3482–3493.(4) Etman A. S.; Abdelhamid H. N.; Yuan Y.; Wang L.; Zou X.; Sun J. Facile Water Based Strategy for Synthesizing MoO3-x Nanosheets: Efficient Visible Light Photocatalyst for Dye Degradation. ACS Omega. in Press.
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