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

Energy landscape for Li-ion diffusion in the garnet-type solid electrolyte Li6.5_{6.5}La3_3Zr1.5_{1.5}Nb0.5_{0.5}O12_{12} (LLZO-Nb)

A comprehensive understanding of the nexus of diffusion mechanisms on the atomic scale as well as structural influences on the ionic motion in solid electrolytes is key for further development of high-performing all-solid-state batteries. Therefore, current research not only focuses on the search for innovative materials, but also on the study of diffusion pathways and ion dynamics in ionic conductors. In this context, we report on the extended characterization of the ionic electrolyte Li$_{6.5}$La$_3$Zr$_{1.5}$Nb$_{0.5}$O$_{12}$ (LLZO-Nb). The commercially available material is analyzed by a combination of powder X-ray (either lab- or synchrotron-based) and neutron diffraction. Details of lithium disorder were obtained from high-resolution neutron diffraction data, from which the ionic transport of Li ions was determined by applying the maximum entropy method in combination with the one-particle potential formalism