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Studies of argyrodite Li 6 PS 5 Cl as solid electrolyte are increasing, motivated by its high ionic conductivity and its easy processability. However, development of All-Solid-State-Batteries lies on the ability to produce such compound with a good purity. This work presents the characterization results of different argyrodite grades: commercial and homemade one. In parallel, synthesis of Li 6 PS 5 Cl from Li 4 P 2 S 7 precursor is reported for the first time. The purity effect on these properties will be explored by using X-ray diffraction coupled with Raman spectroscopy and electrochemical impedance spectroscopy techniques. Crystal properties investigations will be particularly conducted, given that smaller crystallite sizes would lead to an enhanced ionic percolation network by increasing the microstructure homogeneity in catholyte. Such SE could be obtained only by avoiding a post synthesis annealing treatment. Finally, electrochemical properties of the different reported grades will also be discussed in this study. We demonstrate here 1. the beneficial effect of Li 4 P 2 S 7 to obtain a pure sulfur-based solid electrolyte with nanometric crystallites without solid state synthesis and 2. the impact of impurities on its ionics and electrochemical properties. [Display omitted] • Characterization of commercial and homemade Li 6 PS 5 Cl grades by XRD, Raman and EIS. • New route synthesis of Li 6 PS 5 Cl through amorphous phase based on Li 4 P 2 S 7 compound. • Preparation of nanometric crystallites of Li 6 PS 5 Cl with enhanced ionic conductivity. • Influence of impurities on electrochemical properties. [ABSTRACT FROM AUTHOR]

Bringing solid-state lithium batteries to market is a challenge; in part because their fabrication requires a technically difficult step of solid-electrolyte separator assembly, and because thus far, solid-state cells have only cycled under high pressure. Here, we address both these bottlenecks by assembling lithium-ion batteries based on the argyrodite Li 6 PS 5 Cl as the electrolyte using standard coating processes. Moreover, we upscaled to 10 cm2 pouch cells in a dry room by a double casting technique, thanks to the use of fluorine-free polyisobutene as the binder and nanosilicon and LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) respectively as the anode and cathode active materials. Electrode casting is shown to significantly improve the cycling stability when compared to the conventional pelletizing process. The all-coated pouch cells, cycled at a pressure as low as 1 MPa over 160 cycles, show a better capacity retention than the pelletized cells cycling under >100 MPa. The higher performance of the sheet-type cell is thought to originate in the better densification and homogeneity of the cell, attested by its low resistance. [Display omitted] • Si-NMC pouch cells with Li 6 PS 5 Cl solid electrolyte. • Both electrodes and separator casted via conventional ink coating process. • Cell scaled up from 0.4 cm2 (pelletized cell) to 10 cm2 (all-coated pouch cell). • The coating process improved long-term stability. • Pouch cells cycled under 1 MPa perform better than pelletized cells at 127 MPa. [ABSTRACT FROM AUTHOR]