| 1. |
- Sun, Bing, et al.
(författare)
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Towards Solid-State 3D-Microbatteries using Functionalized Polycarbonate-based Polymer Electrolytes
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - 1944-8244 .- 1944-8252. ; 10:3, s. 2407-2413
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Tidskriftsartikel (refereegranskat)abstract
- 3D-microbatteries (3D-MBs) impose new demands for theselection, fabrication and compatibility of the different battery components, notleast the electrolytes. Herein, solid polymer electrolytes (SPEs) based on poly(trimethylene carbonate) (PTMC) have been implemented in 3D-MB systems. 3D electrodes of two different architectures, LiFePO4-coated carbon foams and Cu2O-coated Cu nanopillars, have been coated with SPEs and used in Li-cells. Functionalized PTMC with hydroxyl end groups was found to enable uniform and well-covering coatings on LiFePO4-coated carbon foams, although the cell cycling performance was limited by the large SPE resistance. By employing a SPE prepared from a copolymer of TMC and caprolactone (CL), with higher ionic conductivity, Li-cells composed of Cu2O-coated Cu nanopillars were constructed and tested both at room temperature and 60 °C. The footprint areal capacity of the cells was ca. 0.02 mAh cm-2 for an area gain factor (AF) of 2.5, and 0.2 mAh cm-2 for a relatively dense nanopillar-array (AF=25) at a current density of 0.008 mA cm-2at ambient temperature (22±1 °C). These results provide new routes towards the realization of all-solid-state 3D-MBs.
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| 2. |
- Asfaw, Habtom D., 1986-, et al.
(författare)
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Charting the course to solid-state dual-ion batteries
- 2024
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Ingår i: Carbon Energy. - : John Wiley & Sons. - 2637-9368 .- 2637-9368. ; 6:3
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Forskningsöversikt (refereegranskat)abstract
- An electrolyte destined for use in a dual-ion battery (DIB) must be stable at the inherently high potential required for anion intercalation in the graphite electrode, while also protecting the Al current collector from anodic dissolution. A higher salt concentration is needed in the electrolyte, in comparison to typical battery electrolytes, to maximize energy density, while ensuring acceptable ionic conductivity and operational safety. In recent years, studies have demonstrated that highly concentrated organic electrolytes, ionic liquids, gel polymer electrolytes (GPEs), ionogels, and water-in-salt electrolytes can potentially be used in DIBs. GPEs can help reduce the use of solvents and thus lead to a substantial change in the Coulombic efficiency, energy density, and long-term cycle life of DIBs. Furthermore, GPEs are suited to manufacture compact DIB designs without separators by virtue of their mechanical strength and electrical performance. In this review, we highlight the latest advances in the application of different electrolytes in DIBs, with particular emphasis on GPEs.
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| 3. |
- Edström, Daniel, 1986-, et al.
(författare)
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Forces on parallel three-phase AC-conductors during a phase to ground fault
- 2019
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of calculating forces on high current solid conductors, as is present in various types of electrical installations e.g. in substations [1]. An example of such an installation with three parallel conductors is shown in Figure 1. The conductor forces are important for the design of the station, in particular for the conductor geometry and mechanical support.
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| 4. |
- Edström, Daniel, 1986-
(författare)
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Growth and Mechanical Properties of Transition Metal Nitrides and Carbides
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The atomic-scale dynamical processes at play during film growth cannot be resolved by even the most advanced experimental methods. As such, computational methods, and chiefly classical molecular dynamics, are the only available research tools to study these processes. The investigation of key dynamical processes during thin film growth yields a deeper understanding of the film growth evolution, ultimately allowing for the optimization of experimental parameters and tailoring of film properties. This thesis details the study of fundamental surface dynamics processes, and the role played by primary diffusing species, during TiN film growth, here employed as a model system for transition metal nitrides in general. It is found that Ti adatoms and TiN2 admolecules are the fastest diffusing species, and the species which most rapidly descend from islands onto the growing film. Thus, they are the main contributors and players in driving the layer-by-layer growth mode. TiN3 admolecules, in contrast, are essentially stationary and thereby promote multilayer growth. Large-scale growth simulations reveal that tailoring the incident N/Ti ratio and N kinetic energy significantly affects the growth mode and film microstructure.The mechanical properties of ternary transition metal nitride and carbide alloys, investigated using density functional theory, are also discussed herein, in comparison to recent experimental results. By optimizing the valence electron concentration in these compounds, the occupation of shear-compliant d‑t2g electronic states can be maximized. The investigation of M1M2N alloys, where M1 = Ti or V and M2 = W or Mo, with different structures demonstrates that this optimization leads to enhanced ductility, and thereby toughness, in transition metal nitride alloys regardless of the degree of ordering on the metal sublattice. Estimations based on the calculation of the mechanical properties of the corresponding M1M2C transition metal carbide alloys indicate that these materials remain brittle. However, charge density analysis and calculations of stress/strain curves reveal features commonly associated with ductile materials.
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| 5. |
- Edström, Daniel, 1986-, et al.
(författare)
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Mechanical properties of VMoNO as a function of oxygen concentration : Toward development of hard and tough refractory oxynitrides
- 2019
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Institute of Physics (AIP). - 0734-2101 .- 1520-8559. ; 37:6
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Tidskriftsartikel (refereegranskat)abstract
- Improved toughness is a central goal in the development of wear-resistant refractory ceramic coatings. Extensive theoretical and experimental research has revealed that NaCl-structure VMoN alloys exhibit surprisingly high ductility combined with high hardness and toughness. However, during operation, protective coatings inevitably oxidize, a problem that may compromise material properties and performance. Here, the authors explore the role of oxidation in altering VMoN properties. Density functional theory and theoretical intrinsic hardness models are used to investigate the mechanical behavior of cubic V0.5Mo0.5N1-xOx solid solutions as a function of the oxygen concentration x. Elastic constant and intrinsic hardness calculations show that oxidation does not degrade the mechanical properties of V0.5Mo0.5N. Electronic structure analyses indicate that the presence of oxygen reduces the covalent bond character, which slightly lowers the alloy strength and intrinsic hardness. Nevertheless, the character of metallic d-d states, which are crucial for allowing plastic deformation and enhancing toughness, remains unaffected. Overall, the authors' results suggest that VMoNO oxynitrides, with oxygen concentrations as high as 50%, possess high intrinsic hardness, while still being ductile. Published by the AVS.
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| 6. |
- Edström, Daniel, 1986-, et al.
(författare)
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TiN film growth on misoriented TiN grains with simultaneous low-energy bombardment : Restructuring leading to epitaxy
- 2019
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 688
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Tidskriftsartikel (refereegranskat)abstract
- We perform large-scale molecular dynamics simulations of TiN deposition at 1200 K on TiN substrates consisting of under-stoichiometric (N/Ti = 0.86) misoriented grains. The energy of incoming Ti atoms is 2 eV and that of incoming N atoms is 10 eV. The simulations show that misoriented grains are reoriented during the early stages of growth, after which the film grows 001 epitaxially and is nearly stoichiometric. The grain reorientation coincides with an increase in film N/Ti ratio. As the grains reorient, additional nitrogen can no longer be accommodated, and the film composition becomes stoichiometric as the overlayer grows epitaxially.
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| 7. |
- Hakim, Charifa, et al.
(författare)
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Development of P2 or P2/P3 cathode materials for sodium-ion batteries by controlling the Ni and Mn contents in Na0.7CoxMnyNizO2 layered oxide
- 2023
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 438
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Tidskriftsartikel (refereegranskat)abstract
- Layered oxide cathode materials with the general formula NaxTMO2 (TM = transition metals) have shown promises as electrode materials for future large-scale sodium-ion batteries. However, several challenges including capacity degradation at high voltage, phase transitions as well as structural sensitivity to minor changes in the sodium and transition metal contents during the synthesis process have hampered their development. Herein, we report a systematic investigation of the impact of replacing cobalt by either manganese or nickel on the structural and electrochemical properties of Na0.7CoxMnyNizO2 (x + y + z = 1) layered oxide materials using a variety of analysis and electrochemical techniques. Mixed phases of P2 and P3 cathode materials are obtained through a slight increase of the nickel content, while increasing the manganese content showed little effect on the P2-type structure. Increasing manganese content is shown to lead to lower discharge capacity but excellent capacity retention after 100 cycles, while nickel-rich electrodes exhibit higher discharge capacity approaching 120 mAh/g but poor rate capability performance.
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| 8. |
- Hakim, Charifa, et al.
(författare)
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P-doped Hard Carbon as Anode Material for Sodium-ion Batteries
- 2019
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Ingår i: Proceedings of 2019 7th international renewable and sustainable energy conference (IRSEC). - : IEEE. - 9781728151526 ; , s. 754-756
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Konferensbidrag (refereegranskat)abstract
- The P-doped hard carbon was synthesized using carboxymethyl cellulose and phosphoric acid as the carbon and phosphorus precursors, respectively. The X-ray photoelectron spectroscopy (XPS) analysis reveals that the doped phosphorus atoms can incorporate into the carbon framework and most of them are connecting with carbon atoms to form P-C bonds. When used as anodes in sodium ion batteries, the obtained un-doped and P-doped hard carbon show poor electrochemical performances. The results indicate further optimization of the synthesis process is required. However, this approach opens up new possibilities to improve electrochemical performance of hard carbon anodes.
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| 10. |
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