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- Graae, Kristoffer Visti, et al.
(författare)
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Time and space resolved operando synchrotron X-ray and Neutron diffraction study of NMC811/Si–Gr 5 Ah pouch cells
- 2023
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Ingår i: Journal of Power Sources. - 0378-7753. ; 570
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Tidskriftsartikel (refereegranskat)abstract
- Silicon–Graphite blended electrodes in Li-ion batteries have been proposed as a way to harness the high capacity of Si as an anode material, while minimising the negative effects of their large volume expansion. NMC 811 is the current state-of-the-art layered oxide cathode material, where the cobalt content of the cathode has been minimised. These are the two of the most promising materials for achieving electric vehicle targets in terms of performance, cyclability and price, however their degradation mechanism is not fully understood. Here these two materials have been used to manufacture 5 Ah prototype multi-layer pouch cells, which are aged and then studied using two complimentary diffraction techniques. Neutron diffraction has enabled a quantitative analysis of phase transitions in Si–Gr anodes in a pristine and degraded cell, and the alloying behaviour of Si and Li has been inferred by comparison of identical cells with either graphite or Si–Gr anodes. Synchrotron X-ray Diffraction has been used to make an operando 2D map of the cathode and anode lithiation in the pouch cell, as well as to map the volume expansion across the cell. This approach has revealed that degradation entails significant inhomogeneities across both electrodes, linked to the inhomogeneous volume expansion of the Si–Gr anodes.
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| 4. |
- Siebeneichler, Stefanie, et al.
(författare)
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Making a Hedgehog Spin-Vortex State Possible : Geometric Frustration on a Square Lattice
- 2024
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Ingår i: Chemistry of Materials. - 0897-4756 .- 1520-5002. ; 36:8, s. 3546-3554
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic materials with noncollinear spin arrangements are of considerable interest owing to their potential use in emerging computational technologies and memory devices. Competing magnetic interactions, i.e., magnetic frustration, are one of the main origins of noncollinear magnetic structures. While frustrated systems have been mainly studied among magnetic insulators, combining magnetic frustration with electrical conductivity can allow simultaneous charge and spin manipulation, which is crucial for the design of electronic devices. Here, we present a new intermetallic solid solution LaMn2–xAu4+x, whose crystal structure accommodates magnetically frustrated Mn square nets. Powder neutron diffraction and first-principles analysis provide evidence that the metallic LaMn2–xAu4+x phase can host the frustration-driven hedgehog spin-vortex crystal─a rare noncollinear magnetic state, which was previously exclusively observed for iron pnictides.
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