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Li 6 PS 5 X (X = Cl, Br, I) argyrodites possess high ionic conductivity but with rather scattered values due to various processing conditions. In this work, Li 6 PS 5 X solid electrolytes were prepared by solid-state sintering or mechanical alloying and optimized with or without excess Li 2 S. Solid-state sintering prefers excess Li 2 S, whereas mechanical alloying prefers stoichiometric Li 2 S to synthesize high-purity samples with high ionic conductivity. Solid-state sintering is also more suitable than mechanical milling for high ionic conductivity. Li 6 PS 5 Cl with the highest ionic conductivity among Li 6 PS 5 X was comprehensively characterized for electrochemical performance and air stability. MoS 2 /Li 6 PS 5 Cl all-solid-state batteries assembled with Li 6 PS 5 Cl-coated MoS 2 as cathode and with Li 6 PS 5 Cl as solid electrolyte demonstrate high capacity and good cycling stability. [ABSTRACT FROM AUTHOR]

Solution-processability is one of the merits of sulfide solid electrolytes because it is a facile and scalable process to construct a thin electrolyte coating layer on active material powders to reduce the interfacial resistance. Herein the argyrodite-type Li 6 PS 5 X is synthesized by an one-step solution-process method with ethanol, which avoids the multi-step processes and toxic solvent adopted in other reported works, and greatly reduces the processing time. The as-synthesized Li 6 PS 5 Cl has room temperature ionic conductivity of 0.21 mS cm−1 and comparable Li-dendrite suppression ability to solid-state-sintered Li 6 PS 5 Cl, despite of the unavoidable impurities due to the use of the protic solvent. By coating Li 6 PS 5 Cl on LiCoO 2 particles with the one-step solution process, the assembled all-solid-state battery exhibits higher capacity and better rate capability than the uncoated baseline battery. The improved electrochemical performance is attributed to a well-maintained interfacial resistance during cycling by the interfacial architecture, though the performance is not good yet and need to be further improved. The one-step solution-process method can be used for coating cathode materials. Image 1 • One-step solution-process synthesis is optimized for preparation of Li 6 PS 5 X. • Li 6 PS 5 Cl is synthesized with one-step solution process from raw materials. • The interfacial performance is enhanced by the thin and uniform electrolyte coating. • An improved cycling stability is achieved from the coated all-solid-state cell. [ABSTRACT FROM AUTHOR]

Abstract: The M-doped GdBa2Cu3− x M x O7− δ (Mystems have been systemically investigated by means of XRD, SEM and Raman spectroscopy. The results show that the samples undergo an orthorhombic–tetragonal (O–T) phase transition near x =0.10 by Fe ions doping. Although all the Zn-doped samples remain orthorhombic structure, the changes of the lattice parameters in the Zn-doped samples may induce a structural distortion because of Jahn–Teller effect. The crystallite appearances alter perceptibly with the Fe/Zn doping contents. Meanwhile, the changes of the typical Raman models are discussed. The research has found that the Raman modes present distinctive behaviors by Zn or Fe ions doping, which strongly depend on the crystal structure, especially on O–T phase transition. The effects of structure phase transition and the changes of the phonon vibration on the mechanism of electrical transport properties by Fe and Zn doping in different Cu sites are also discussed. [Copyright &y& Elsevier]