Details

Autor(en) / Beteiligte

• Sedlmaier, Stefan J
• Indris, Sylvio
• Dietrich, Christian
• Yavuz, Murat
• Dräger, Christoph
• von Seggern, Falk
• Sommer, Heino
• Janek, Jürgen

Titel

Li4PS4I: A Li+ Superionic Conductor Synthesized by a Solvent-Based Soft Chemistry Approach

Ist Teil von

• Chemistry of materials, 2017-02, Vol.29 (4), p.1830-1835

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2017

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• A novel crystalline lithium superionic conductor, Li4PS4I, has been discovered utilizing a solvent-based synthesis approach. It was found that the starting material Li3PS4·DME reacts with LiI in a 1:1 ratio in DME to give a precursor that results in Li4PS4I after soft heat treatment at around 200 °C in vacuum. Its crystal structure was solved ab initio by evaluating both X-ray (Mo-Kα1) and neutron (TOF, GEM, ISIS) powder diffraction data, in a combined refinement (P4/nmm, Z = 2, a = 8.48284(12) Å, c = 5.93013(11) Å, wRp = 0.02973, GoF = 1.21499). The final structure model comprises, besides Li+ ions, isolated PS4 3– tetrahedra in a layer-like arrangement perpendicular to the c-axis that are held apart by I– ions. The Li+ ions are distributed over five partially occupied sites residing in 4-, 5-, and 6-fold coordination environments. A topostructural analysis of the voids and channels within the PS4I4– substructure suggested a three-dimensional migration pathway system for the Li+ ions in Li4PS4I. The Li+ ion mobility was studied by temperature-dependent impedance spectroscopy as well as 7Li solid-state nuclear magnetic resonance (NMR) spectroscopy including the measurement of spin–lattice relaxation rates T 1 –1. The total ionic conductivity was determined to be in the range of 6.4 × 10–5 to 1.2 × 10–4 S·cm–1 at room temperature with activation energies (E A) of 0.37 to 0.43 eV. The NMR analyses revealed a hopping rate of the Li+ ions of τ–1 = 5 × 108 s–1 corresponding to a bulk conductivity of 1.3 × 10–3 S·cm–1 at 500 K and an activation energy E A = 0.23(1) eV.