Li5SnP3: a member of the series Li10+4xSn2−xP6 for x=0 comprising the fast lithium‐ion conductors Li8SnP4 (x=0.5) and Li14SnP6 (x=1)

The targeted search for suitable solid‐state ionic conductors requires a certain understanding of the conduction mechanism and the correlation of the structures and the resulting properties of the material. Thus, the investigation of various ionic conductors with respect to their structural composition is crucial for the design of next‐generation materials as demanded. We report here on Li(5)SnP(3) which completes with x=0 the series Li(10+4x )Sn(2−x )P(6) of the fast lithium‐ion conductors α‐ and β‐Li(8)SnP(4) (x=0.5) and Li(14)SnP(6) (x=1). Synthesis, crystal structure determination by single‐crystal and powder X‐ray diffraction methods, as well as (6)Li, (31)P and (119)Sn MAS NMR and temperature‐dependent (7)Li NMR spectroscopy together with electrochemical impedance studies are reported. The correlation between the ionic conductivity and the occupation of octahedral and tetrahedral sites in a close‐packed array of P atoms in the series of compounds is discussed. We conclude from this series that in order to receive fast ion conductors a partial occupation of the octahedral vacancies seems to be crucial

Fast Ionic Conductivity in the Most Lithium-Rich Phosphidosilicate Li14SiP6.

Solid electrolytes with superionic conductivity are required as a main component for all-solid-state batteries. Here we present a novel solid electrolyte with three-dimensional conducting pathways based on "lithium-rich" phosphidosilicates with ionic conductivity of σ > 10-3 S cm-1 at room temperature and activation energy of 30-32 kJ mol-1 expanding the recently introduced family of lithium phosphidotetrelates. Aiming toward higher lithium ion conductivities, systematic investigations of lithium phosphidosilicates gave access to the so far lithium-richest compound within this class of materials. The crystalline material (space group Fm3m), which shows reversible thermal phase transitions, can be readily obtained by ball mill synthesis from the elements followed by moderate thermal treatment of the mixture. Lithium diffusion pathways via both tetrahedral and octahedral voids are analyzed by temperature-dependent powder neutron diffraction measurements in combination with maximum entropy method and DFT calculations. Moreover, the lithium ion mobility structurally indicated by a disordered Li/Si occupancy in the tetrahedral voids plus partially filled octahedral voids is studied by temperature-dependent impedance and 7Li NMR spectroscopy

Aliovalent substitution in phosphide‐based materials – Crystal structures of Na 10

Funding Information: The work was carried out as part of the research project ASSB coordinated by ZAE Bayern. The project is funded by the Bavarian Ministry of Economic Affairs, Regional Development and Energy. We thank Christoph Wallach for recording the Raman spectrum. Open access funding enabled and organized by Projekt DEAL. Publisher Copyright: © 2021 The Authors. Zeitschrift für anorganische und allgemeine Chemie published by Wiley-VCH GmbHRecently, ternary lithium phosphides have been studied intensively owing to their high lithium ion conductivities. Much less is known about the corresponding sodium-containing compounds, and during investigations aiming for sodium phosphidotrielates, two new compounds have been obtained. The sodium phosphidoaluminumtantalate Na10AlTaP6, at first obtained as a by-product from the reaction with the container material, crystallizes in the monoclinic space group P21/n (no. 14) with lattice parameters of a=8.0790(3) Å, b=7.3489(2) Å, c=13.2054(4) Å, and β=90.773(2)°. The crystal structure contains dimers of edge-sharing [(Al0.5Ta0.5)P4] tetrahedra with a mixed Al/Ta site. DFT calculations support the presence of this type of arrangement instead of homonuclear Al2P6 or Ta2P6 dimers. The 31P and 23Na MAS NMR as well as the Raman spectra confirm the structure model. The assignment of the chemical shifts is confirmed applying the DFT-PBE method on the basis of the ordered structural model with mixed AlTaP6 dimers. Thesodium phosphidogallate Na3GaP2 crystallizes in the orthorhombic space group Ibam (no. 72) with lattice parameters of a=13.081(3) Å, b=6.728(1) Å, and c=6.211(1) Å and is isotypic to Na3AlP2. Na3GaP2 exhibits linear chains of edge-sharing 1∞[GaP4/2] tetrahedra. For both compounds band structure calculations predict indirect band gaps of 2.9 eV.Peer reviewe