Exploring Route for Pyrophosphate-based Electrode Materials: Interplay between Synthesis and Structure |
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| Authors: | Anastasia M. Alekseeva Ilya V. Tertov Andrey V. Mironov Ivan V. Mikheev Oleg A. Drozhzhin Emiliya V. Zharikova Marina G. Rozova Evgeny V. Antipov |
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| Affiliation: | 1. Chemistry Department, Lomonosov Moscow State University, 119991 Moscow, Russia;2. Chemistry Department, Lomonosov Moscow State University, 119991 Moscow, Russia Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, 143026 Moscow, Russia |
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| Abstract: | New sodium vanadium(III) hydrogenphosphate hydrate NaV(HPO4)2(H2O)0.5 and sodium vanadium(III) hydrogenphosphate β-NaV(HPO4)2 were prepared in mild hydrothermal conditions. The crystal structures of NaV(HPO4)2(H2O)0.5 [space group Cc, Z = 4, a = 8.46174(19) Å, b = 9.52583(19) Å, c = 8.69376(15) Å, β = 110.9553(11) °, V = 654.41(2) Å3] and β-NaV(HPO4)2 [space group C2/c, Z = 4, a = 7.8681(3) Å, b = 9.8451(3) Å, c = 8.5180(2) Å, β = 107.626(2) °, V = 628.85(3) Å3] were solved and refined from X-ray powder diffraction data. Both compounds were used as precursors in a new route for the preparation of attractive cathode material β-NaVP2O7. The formation of the structure motive providing fast sodium ion diffusion at the first synthesis stage and its further conservation upon stepwise dehydration was revealed. The oversized Na+-embedding channels are stabilized by site-coordinated water in NaV(HPO4)2(H2O)0.5 structure. The topology resemblance and difference in known sodium vanadium(III) complex phosphates are discussed. |
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| Keywords: | Sodium vanadium(III) monohydrogenphosphate hydrate Sodium vanadium(III) monohydrogenphosphate Sodium vanadium(III) pyrosphosphate Cathode material Hydrothermal synthesis |
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