| 1. |
- Drvarič Talian, Sara, et al.
(författare)
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Fluorinated Ether Based Electrolyte for High-Energy Lithium-Sulfur Batteries: Li+ Solvation Role behind Reduced Polysulfide Solubility
- 2017
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 29:23, s. 10037-10044
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Tidskriftsartikel (refereegranskat)abstract
- By employing new electrolytes, the polysulfide shuttle phenomenon, one of the main problems of lithium-sulfur (Li-S) batteries, can be significantly reduced. Here we present excellent Coulombic efficiencies as well as adequate performance of high-energy Li-S cells by the use of a fluorinated ether (TFEE) based electrolyte at low electrolyte loading. The observed altered discharge profile was investigated both by electrochemical experiments and an especially tailored COSMO-RS computational approach, while the details of the discharge mechanism were elucidated by two operando techniques: XANES and UV-vis spectroscopy. A significant decrease of polysulfide solubility compared to tetraglyme is due to different Li+ solvation mode.
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| 2. |
- Jana, Somnath, et al.
(författare)
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LaSrVMoO6 : A case study for A-site covalency-driven local cationic order in double perovskites
- 2012
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 86:1
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Tidskriftsartikel (refereegranskat)abstract
- An unusual atomic scale chemical fluctuation in LaSrVMoO6, in terms of narrow patches of La, V and Sr,Mo-rich phases, has been probed in detail to understand the origin of such a chemical state. Exhaustive tuning of the equilibrium synthesis parameters showed that the extent of phase separation can never be melted down below a unit cell dimension making it impossible to achieve the conventional B-site ordered structure, which establishes that the observed "inhomogeneous" patchlike structure with minimum dimension of few angstroms is a reality in LaSrVMoO6. Therefore another type of local chemical order, hitherto unknown in double perovskites, gets introduced here. X-ray diffraction, electron microscopy elemental mapping, magnetic, and various spectroscopic studies have been carried out on samples, synthesized under different conditions. These experimental results in conjunction with ab initio electronic structure calculation revealed that it is the energy stability, gained by typical La-O covalency as in LaVO3, that leads to the preferential La, V and Sr,Mo ionic proximity, and the consequent patchy structure.
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| 3. |
- Le Pham, Phuong Nam, et al.
(författare)
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Prussian blue analogues for potassium-ion batteries: insights into the electrochemical mechanisms
- 2023
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 11:6, s. 3091-3104
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive description of the electrochemical mechanisms of the Prussian Blue Analogue (PBA) K1.67Mn0.65Fe0.35[Fe(CN)6]0.92·0.45H2O is obtained by combining several complementary ex situ and operando physico-chemical characterisation techniques. This particular PBA, which shows very good electrochemical performance as a cathode material in potassium-ion batteries (PIBs), undergoes three successive redox reactions during the (de-)potassiation that are hereby identified by ex situ57Fe Mössbauer spectroscopy and operando Mn and Fe K-edge X-ray absorption spectroscopy. These reactions come along with notable modifications of the crystal structure, which are followed in real time by operando X-ray diffraction. The correlation of these results, interpreted with the support of chemometric methods, also reveals the limitations of this PBA, probably related to the deactivation of the Mn undergoing extensive reversible Jahn-Teller distortion during cycling as well as possible dissolution in the electrolyte. These results underline that optimisation of the chemical composition of PBAs is a crucial step towards the preparation of reliable and stable PBA-based cathodes for PIBs.
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