| 1. |
- 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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| 2. |
- Doubaji, Siham, et al.
(författare)
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On the P2-NaxCo1−y(Mn2/3Ni1/3)yO2 Cathode Materials for Sodium-Ion Batteries : Synthesis, Electrochemical Performance, and Redox Processes Occurring during the Electrochemical Cycling
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 10:1, s. 488-501
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Tidskriftsartikel (refereegranskat)abstract
- P2-type NaMO2sodiated layered oxides withmixed transition metals are receiving considerable attention foruse as cathodes in sodium-ion batteries. A study on solidsolution (1−y)P2-NaxCoO2−(y)P2-NaxMn2/3Ni1/3O2(y=0,1/3, 1/2, 2/3, 1) reveals that changing the composition of thetransition metals affects the resulting structure and the stabilityof pure P2 phases at various temperatures of calcination. For 0≤y≤1.0, the P2-NaxCo(1−y)Mn2y/3Niy/3O2solid-solutioncompounds deliver good electrochemical performance whencycled between 2.0 and 4.2 V versus Na+/Na with improved capacity stability in long-term cycling, especially for electrodematerials with lower Co content (y= 1/2 and 2/3), despite lower discharge capacities being observed. The (1/2)P2-NaxCoO2−(1/2)P2-NaxMn2/3Ni1/3O2composition delivers a discharge capacity of 101.04 mAh g−1with a capacity loss of only 3% after 100cycles and a Coulombic efficiency exceeding 99.2%. Cycling this material to a higher cutoffvoltage of 4.5 V versus Na+/Naincreases the specific discharge capacity to≈140 mAh g−1due to the appearance of a well-defined high-voltage plateau, but afteronly 20 cycles, capacity retention declines to 88% and Coulombic efficiency drops to around 97%. In situ X-ray absorption near-edge structure measurements conducted on composition NaxCo1/2Mn1/3Ni1/6O2(y= 1/2) in the two potential windows studiedhelp elucidate the operating potential of each transition metal redox couple. It also reveals that at the high-voltage plateau, all ofthe transition metals are stable, raising the suspicion of possible contribution of oxygen ions in the high-voltage plateau.
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| 3. |
- Gond, Ritambhara, et al.
(författare)
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A Lignosulfonate Binder for Hard Carbon Anodes in Sodium-Ion Batteries : A Comparative Study
- 2021
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society. - 2168-0485. ; 9:37, s. 12708-
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Tidskriftsartikel (refereegranskat)abstract
- An important factor in the development of sodium-ion batteries (SIBs) is the use of cheap and sustainable materials. Sodium lignosulfonate, a lignin derivative, is demonstrated here as an attractive, "green", water-soluble, and potentially cost-effective binder for use in hard carbon anodes for SIBs. A comparison of its battery cycling performance is made against other binders including sodium carboxymethyl cellulose and lignin, obtained from the kraft process, as well as sodium alginate, derived from algae. Apart from lignin, which requires processing in N-methyl-2-pyrrolidone, the other three binders are water-soluble. Lignosulfonate shows comparable or better performance, with high capacity retention and stability, when using 1 M NaPF6 in propylene carbonate or ethylene carbonate:diethyl carbonate electrolytes for both half- and full-cells (against a Prussian white cathode). Further improvements are observed when including styrene-butadiene rubber as a co-binder. X-ray photoelectron spectroscopy demonstrates similar solid electrolyte interphase compositions after the initial sodium insertion for both lignosulfonate and carboxymethyl cellulose binders. However, after subsequent cycling, the surface layer composition and thickness are found to be dependent on the binder. For the lignosulfonate-based electrode, the layer appears thicker but comprises a smaller fraction of carbon-oxygen species. © 2021 The Authors.
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| 4. |
- 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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| 5. |
- 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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| 9. |
- Kotronia, Antonia, et al.
(författare)
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Catalytically graphitized freestanding carbon foams for 3D Li-ion microbatteries
- 2020
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Ingår i: Journal of Power Sources Advances. - : Elsevier BV. - 2666-2485. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- A long-range graphitic ordering in carbon anodes is desirable since it facilitates Li+ transport within the structure and minimizes irreversible capacity loss. This is of vital concern in porous carbon electrodes that exhibit high surface areas and porosity, and are used in 3D microbatteries. To date, it remains a challenge to graphitize carbon structures with extensive microporosity, since the two properties are considered to be mutually exclusive. In this article, carbon foams with enhanced graphitic ordering are successfully synthesized, while maintaining their bicontinuous porous microstructures. The carbon foams are synthesized from high internal phase emulsion-templated polymers, carbonized at 1000 °C and subsequently graphitized at 2200 °C. The key to enhancing the graphitization of the bespoke carbon foams is the incorporation of Ca- and Mg-based salts at early stages in the synthesis. The carbon foams graphitized in the presence of these salts exhibit higher gravimetric capacities when cycled at a specific current of 10 mA g−1 (140 mAh g−1) compared to a reference foam (105 mAh g−1), which amounts to 33% increase.
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