A novel crystalline lithium superionic conductor, Li 4 PS 4 I, has been discovered utilizing a solvent-based synthesis approach. It was found that the starting material Li 3 PS 4 •DME reacts with LiI in a 1:1 ratio in DME to give a precursor that results in Li 4 PS 4 I after soft heat treatment at around 200 °C in vacuum. Its crystal structure was solved ab initio by evaluating both X-ray (Mo-Kα 1 ) 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, wR p = 0.02973, GoF = 1.21499). The final structure model comprises, besides Li + ions, isolated PS 4 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 PS 4 I 4− substructure suggested a threedimensional migration pathway system for the Li + ions in Li 4 PS 4 I. The Li + ion mobility was studied by temperature-dependent impedance spectroscopy as well as 7 Li 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 × 10 8 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.

A new setup for in situ experiments with up to eight electrochemical cells, especially battery coin cells, and the corresponding custom‐made in situ cells are presented. The setup is primarily optimized for synchrotron powder diffraction measurements. As a newly constructed experimental setup, the in situ coin cell holder was tested for positional errors of the cells and the reliability of the diffraction as well as electrochemical measurements. The overall performance characteristics of the sample holder are illustrated by measurements on LiMn2O4 and LiNi0.35Fe0.3Mn1.35O4 spinel‐based positive electrode materials.

Lithium transition metal oxides are commonly used as cathode materials in modern mobile and stationary power supplies. Lithium transition metal fluorides are an interesting new class of materials for lithium ion batteries featuring a higher voltage due to substitution of oxygen by the more electronegative fluorine. A sol-gel based process with trifluoroacetic acid as fluorine source was used to synthesize LiNiFeF 6 . Ball-milling with carbon and binder was applied to obtain an electrochemical active LiNiFeF 6 /carbon/binder nano composite. In this study we report on the first electrochemical characterization of a quaternary lithium transition metal fluoride as positive electrode for lithium ion batteries, containing two different transition metals. After 20 cycles of galvanostatic cycling a reversible specific capacity of 88 mAh/g, which is 92% of the initial specific capacity, was retained. In a rate performance test with rates of up to 1C a reversible capacity of 53 mAh/g was obtained. The electrochemically active redox couple Fe 3+ /Fe 2+ was identified by Mössbauer spectroscopy and cyclic voltammetry.The search for alternative cathode materials for lithium batteries to replace common oxide materials has generated considerable research activity to provide reliable battery systems for large-scale applications such as electric vehicles and grid storage. Previous investigations have been performed on a large number of compounds that can be applied as cathode materials for secondary lithium ion batteries such as layered LiMO 2 , silicates Li 2 MSiO 4 and polyanionic olivines LiMPO 4 (M = Fe, Mn, Co). 1,2 Several hundred publications have been published on quaternary lithium metal oxides. 4,5 However, no electrochemical investigations are given about quaternary lithium transition metal fluorides as positive electrode materials. Lithium transition metal fluorides in particular are very promising materials compared to common oxide materials with corresponding electrochemically active cations because the more electronegative fluorine atoms increase the redox potential leading to a higher specific energy. 3 Regarding the theoretic capacity of quaternary lithium transition metal fluorides, they could offer multiple redox couples e.g. M 3+/2+ or M 4+/3+ (e.g. M = V, Cr, Mn, Co or Ni) (eq.