| 1. |
- Blidberg, Andreas, 1987-, et al.
(författare)
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Electronic changes in poly(3,4-ethylenedioxythiophene)-coated LiFeSO4F during electrochemical lithium extraction
- 2019
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Ingår i: Journal of Power Sources. - : ELSEVIER SCIENCE BV. - 0378-7753 .- 1873-2755. ; 418, s. 84-89
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Tidskriftsartikel (refereegranskat)abstract
- The redox activity of tavorite LiFeSO4F coated with poly (3,4-ethylenedioxythiophene), i.e. PEDOT, is investigated by means of several spectroscopic techniques. The electronic changes and iron-ligand redox features of this LiFeSO4F-PEDOT composite are probed upon delithiation through X-ray absorption spectroscopy. The PEDOT coating, which is necessary here to obtain enough electrical conductivity for the electrochemical reactions of LiFeSO4F to occur, is electrochemically stable within the voltage window employed for cell cycling. Although the electronic configuration of PEDOT shows also some changes in correspondence of its reduced and oxidized forms after electrochemical conditioning in Li half-cells, its p-type doping is fully retained between 2.7 and 4.1 V with respect to Li+/Li during the first few cycles. An increased iron-ligand interaction is observed in LixFeSO4F during electrochemical lithium extraction, which appears to be a general trend for polyanionic insertion compounds. This finding is crucial for a deeper understanding of a series of oxidation phenomena in Li-ion battery cathode materials and helps paving the way to the exploration of new energy storage materials with improved electrochemical performances.
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| 2. |
- Blidberg, Andreas, 1987-, et al.
(författare)
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Identifying the Electrochemical Processes in LiFeSO4F Cathodes for Lithium Ion Batteries
- 2017
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Ingår i: ChemElectroChem. - : Wiley. - 2196-0216. ; 4:8, s. 1896-1907
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The electrochemical performance of tavorite LiFeSO4F can be considerably improved by coating the material with a conducting polymer (poly(3,4-ethylenedioxythiophene); PEDOT). Herein, the mechanisms behind the improved performance are studied systematically by careful electrochemical analysis. It is shown that the PEDOT coating improves the surface reaction kinetics for the Li-ion insertion into LiFeSO4F. For such coated materials no kinetic limitations remain, and a transition from solid state to solution-based diffusion control was observed at 0.6 mA cm−2 (circa C/2). Additionally, the quantity of PEDOT is optimized to balance the weight added by the polymer and the improved electrochemical function. Post mortem analysis shows excellent stability for the LiFeSO4F-PEDOT composite, and maintaining the electronic wiring is the most important factor for stable electrochemical cycling of LiFeSO4F. The insights and the methodology used to determine the rate-controlling steps are readily transferable to other ion-insertion-based electrodes, and the findings are important for the development of improved battery electrodes.
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| 3. |
- Blidberg, Andreas, 1987-, et al.
(författare)
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Monitoring LixFeSO4F (x = 1, 0.5, 0) Phase Distributions in Operando To Determine Reaction Homogeneity in Porous Battery Electrodes
- 2017
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Ingår i: Chemistry of Materials. - : American Chemical Society. - 0897-4756 .- 1520-5002. ; 29:17, s. 7159-7169
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Tidskriftsartikel (refereegranskat)abstract
- Increasing the energy and power density simultaneously remains a major challenge for improving electrochemical energy storage devices such as Li-ion batteries. Understanding the underlying processes in operating electrodes is decisive to improve their performance. Here, an extension of an in operando X-ray diffraction technique is presented, wherein monitoring the degree of coexistence between crystalline phases in multiphase systems is used to investigate reaction homogeneity in Li-ion batteries. Thereby, a less complicated experimental setup using commercially available laboratory equipment could be employed. By making use of the intrinsic structural properties of tavorite type LiFeSO4F, a promising cathode material for Li-ion batteries, new insights into its nonequilibrium behavior are gained. Differences in the reaction mechanism upon charge and discharge are shown; the influence of adequate electronic wiring for the cycling stability is demonstrated, and the effect of solid state transport on rate performance is highlighted. The methodology is an alternative and complementary approach to the expensive and demanding techniques commonly employed for time-resolved studies of structural changes in operating battery electrodes. The multiphase behavior of LiFeSO4F is commonly observed for other insertion type electrode materials, making the methodology transferable to other new energy storage materials. By expanding the possibilities for investigating complex processes in operating batteries to a larger community, faster progress in both electrode development and fundamental material research can be realized.
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| 4. |
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| 5. |
- Dahbi, Mohammed, et al.
(författare)
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Combustion synthesis and electrochemical performance of Li2FeSiO4/C cathode material for lithium-ion batteries
- 2012
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 205, s. 456-462
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Tidskriftsartikel (refereegranskat)abstract
- A novel preparation technique was developed for synthesizing Li2FeSiO4/C nanoparticles through combustion of reaction mixtures containing silicon source. Li and Fe sources that operate as oxidizers and sucrose that act as a fuel. A systematic investigation of the synthesis parameters, such as the effect of the fuel content, on purity, morphology and electrochemical properties of the samples was performed. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) and electrochemical measurements, respectively. Among the synthesized cathode materials, Li2FeSiO4 obtained with 1.5 mol of sucrose, showed the best electrochemical performance in terms of discharge capacity, cycling stability and rate capability. Discharge capacity of 130 mAh/g at C/20, 88 mAh/g at C/2 and 44 mAh/g at 2C were obtained with no capacity fading after 50 cycles.
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| 6. |
- Dahbi, Mohammed, et al.
(författare)
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Effect of manganese on the structural and thermal stability of Li 0.3Ni0.7 - yCo0.3−yMn2yO2 electrode materials (y =0 and 0.05)
- 2011
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Ingår i: Solid State Ionics. - : Elsevier. - 0167-2738 .- 1872-7689. ; 203:1, s. 37-41
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Tidskriftsartikel (refereegranskat)abstract
- Thermal and structural stabilities of Li(0.3)Ni(0.7)Co(0.3)O(2) and Li(0.3)Ni(0.65)Co(0.25)Mn(0.10)O(2) chemically delithiated cathode materials were studied by X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry. The structure of the Li(0.3)Ni(0.7)Co(0.3)O(2) layered material (S.C. R-3 m) transforms first to the spinel-type structure (S.C. Fd3m) and then to the completely disordered Ni0-type structure (S.C. Fm3m). These structural transitions were accompanied by 10.2% oxygen loss and leads to an exothermic reaction, activated by the electrolyte, more energetic than that of Li(0.3)Ni(0.65)Mn(0.10)O(2) manganese substituted electrode. Furthermore, no structural changes were observed during the thermal treatment of Li(0.3)Ni(0.65)Co(0.25)Mn(0.10)O(2) and relatively lower oxygen loss was recorded. The obtained results prove the positive effect of manganese substitution on the electrochemical features of Li(0.3)Ni(0.7)Co(0.3)O(2).
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| 9. |
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| 10. |
- Eriksson, Rickard, et al.
(författare)
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Electrochemical lithium ion intercalation in Li 0.5Ni 0.25TiOPO 4 examined by in situ X-ray diffraction
- 2012
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738 .- 1872-7689. ; 225:SI, s. 547-550
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Tidskriftsartikel (refereegranskat)abstract
- The complex structural transformations of Li 0.5Ni 0.25TiOPO 4 during electrochemical lithiation have been examined by in situ X-ray diffraction. During the first lithiation two structural changes take place: first a transition to a second monoclinic phase (a = 9.085(4), b = 8.414(5), c = 6.886(5), β = 99.85(4)) and secondly a transition to a third phase with limited long-range order. The third phase is held together by a network of corner sharing Ti-O octahedra and phosphate ions with disordered Ni-Li channels. During delithiation the third phase is partially transformed back to a slightly disordered original phase, Li 0.5Ni 0.25TiOPO 4 without formation of the second intermediate phase. These phase transitions correspond well to the different voltage plateaus that this material shows during electrochemical cycling.
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