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- Sveinbjörnsson, Dadi, et al.
(författare)
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Ionic conductivity and the formation of cubic CaH2 in the LiBH4–Ca(BH4)2 composite
- 2014
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 211:0, s. 81-89
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Tidskriftsartikel (refereegranskat)abstract
- Abstract LiBH4–Ca(BH4)2 composites were prepared by ball milling. Their crystal structures and phase composition were investigated using synchrotron X-ray diffraction and Rietveld refinement, and their ionic conductivity was measured using impedance spectroscopy. The materials were found to form a physical mixture. The composites were composed of α-Ca(BH4)2, γ-Ca(BH4)2 and orthorhombic LiBH4, and the relative phase quantities of the Ca(BH4)2 polymorphs varied significantly with LiBH4 content. The formation of small amounts of orthorhombic CaH2 and cubic CaH2 in a CaF2-like structure was observed upon heat treatment. Concurrent formation of elemental boron may also occur. The ionic conductivity of the composites was measured using impedance spectroscopy, and was found to be lower than that of ball milled LiBH4. Electronic band structure calculations indicate that cubic CaH2 with hydrogen defects is electronically conducting. Its formation along with the possible precipitation of boron therefore has an effect on the measured conductivity of the LiBH4–Ca(BH4)2 composites and may increase the risk of an internal short-circuit in the cells.
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- Younesi, Reza, et al.
(författare)
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A New Look at the Stability of Dimethyl Sulfoxide and Acetonitrile in Li-O2 Batteries
- 2014
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Ingår i: ECS Electrochemistry Letters. - : The Electrochemical Society. - 2162-8726 .- 2162-8734. ; 3:3, s. A15-A18
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Tidskriftsartikel (refereegranskat)abstract
- Dimethyl sulfoxide (DMSO) and acetonitrile (MeCN) have recently been highlighted as promising electrolyte solvents for Li-O2 batteries. Possible reactions between these two solvents and Li2O2 are here discussed using X-ray photoelectron spectroscopy to analyze surface of the Li2O2 powder after direct contact with the solvents for different times of exposure. The results indicated that Li2O2 decomposes DMSO solvents, whereas no indication of degradation of MeCN by Li2O2 was observed.
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