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Subject: Temperature range × WGL Institute: IFWD ×

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    TiNb2O7 and VNB9O25 of ReO3 type in hybrid Mg−Li batteries: Electrochemical and interfacial insights
    (Washington, DC : American Chemical Society, 2020) Maletti, Sebastian; Herzog-Arbeitman, Abraham; Oswald, Steffen; Senyshyn, Anatoliy; Giebeler, Lars; Mikhailova, Daria
    As one of the beyond-lithium battery concepts, hybrid metal-ion batteries have aroused growing interest. Here, TiNb2O7 (TNO) and VNb9O25 (VNO) materials were prepared using a high-temperature solid-state synthesis and, for the first time, comprehensively examined in hybrid Mg−Li batteries. Both materials adopt ReO3-related structures differing in the interconnection of oxygen polyhedra and the resulting guest ion diffusion paths. We show applicability of the compounds in hybrid cells providing capacities comparable to those reached in Li-ion batteries (LIBs) at room temperature (220 mAh g−1 for TNO and 150 mAh g−1 for VNO, both at 0.1 C), their operability in the temperature range between −10 and 60 °C, and even better capacity retention than in pure LIBs, rendering this hybrid technology superior for long-term application. Post mortem X-ray photoelectron spectroscopy reveals a cathode−electrolyte interface as a key ingredient for providing excellent electrochemical stability of the hybrid battery. A significant contribution of the intercalation pseudocapacitance to charge storage was observed for both materials in Li- and Mg−Li batteries. However, the pseudocapacitive part is higher for TNO than for VNO, which correlates with structural distinctions, providing better accessibility of diffusion pathways for guest cations in TNO and, as a consequence, a higher ionic transport within the crystal structure. © 2020 American Chemical Society
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    Rotation of fullerene molecules in the crystal lattice of fullerene/porphyrin: C60 and Sc3N@C80
    (Cambridge : RSC, 2021) Hao, Yajuan; Wang, Yaofeng; Spree, Lukas; Liu, Fupin
    The dynamics of molecules in the solid-state is important to understand their physicochemical properties. The temperature-dependent dynamics of Sc3N@C80 and C60 in the crystal lattice containing nickel octaethylporphyrin (NiOEP) was studied with variable temperature X-ray diffraction (VT-XRD). The results indicate that the fullerene cages (both C60 and C80) in the crystal lattice present stronger libration than the co-crystallized NiOEP in the temperature range of 100–280 K. In contrast to the fullerene cage, the Sc3N cluster shows pronounced rotation roughly perpendicular to the plane of the co-crystallized NiOEP molecule driven by temperature. The obtained temperature dependent dynamic behavior of the Sc3N cluster is different from that of Ho2LuN and Lu3N, regardless of their rather similar structure, indicating the effect of the mass and size of the metal ions.