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Abstract Sulfide solid electrolytes possess high ionic conductivity and moderate dendrite suppression capability, but rather poor compatibility against oxide cathodes and metallic Li. Here, we report O-doped Li 6 PS 5 Br as solid electrolyte synthesized by a facile solid-state sintering. Different from other O-incorporated sulfides, the O atoms in Li 6 PS 5- x O x Br prefer to substitute the S atoms at free S2− sites rather than those at the PS 4 tetrahedra. Remarkably, without deteriorating the ionic conductivity, this inorganic solid electrolyte with O doping exhibits comprehensively enhanced properties including excellent dendrite suppression capability, superior electrochemical and chemical stability against Li metal as well as high voltage oxide cathodes, and good air stability. Li(Ni 0.8 Co 0.1 Mn 0.1)O 2 and LiCoO 2 -based all-solid-state batteries with Li 6 PS 4.7 O 0.3 Br electrolyte deliver high specific capacity, superior rate capability, and outstanding cycling stability accompanied with low interfacial resistivity. This type of inorganic solid electrolytes is promising for all-solid-state batteries with high energy density. Graphical abstract Image 1 Highlights • O-doped Li 6 PS 5 Br argyrodite is synthesized. • O atoms prefer to occupy the free S2− sites rather than the PS 4 tetrahedra. • Li dendrite is intensively suppressed with O incorporation. • The stability against Li and high voltage cathodes are significantly improved. • NCM-811 and LiCoO 2 cells with Li 6 PS 4.7 O 0.3 Br achieve superior performance. [ABSTRACT FROM AUTHOR]

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]