h i g h l i g h t sLi 6 PS 5 Cl solid electrolyte was prepared from ethanol solution. LiCoO 2 was coated with Li 6 PS 5 Cl solid electrolyte by using the solution. All-solid-state batteries using the electrolyte-coated LiCoO 2 operated reversibly. battery Lithium secondary battery Sulfide solid electrolyte Liquid phase method a b s t r a c t A Li 6 PS 5 Cl solid electrolyte was successfully prepared by dissolution-reprecipitation process via ethanol solution. An ionic conductivity of the Li 6 PS 5 Cl solid electrolyte from the homogeneous ethanol solution was 1.4 Â 10 À5 S cm À1 at room temperature. LiCoO 2 particles were coated with the Li 6 PS 5 Cl electrolyte via ethanol solution to form favorable electrode-electrolyte interface with a large contact areas. An allsolid-state cell using the electrolyte-coated LiCoO 2 operated as a rechargeable battery and showed the initial discharge capacity of 45 mAh g À1 at 25 C.

A Li 3 PS 4 solid electrolyte was directly synthesized from Li 2 S and P 2 S 5 by a liquid-phase reaction using N-methylformamide (NMF) and n-hexane as reaction media. After the reaction of Li 2 S and P 2 S 5 , a yellow NMF solution was obtained. The NMF solution was dried at 180 C for 3 hours under vacuum to remove NMF and to obtain a powder. A crystalline phase of the obtained powder from the NMF solution was attributed to Li 3 PS 4 crystals, and the ionic conductivity of the obtained powder was 2.3 Â 10 À6 S cm À1 at 25 C. Electrode-electrolyte composite materials for all-solid-state lithium batteries were prepared by coating the Li 3 PS 4 solid electrolyte onto LiCoO 2 particles using the NMF solution. SEM and EDX analysis showed that LiCoO 2 particles were uniformly coated with the Li 3 PS 4 solid electrolyte. An all-solid-state cell using the LiCoO 2 particles coated with the Li 3 PS 4 solid electrolyte as a positive electrode operated as a secondary battery.

Electrode-solid electrolyte composite materials for all-solid-state lithium batteries were prepared by coating of the Li2S-P2S5 solid electrolyte onto LiCoO2 particles using a N-methylformamide (NMF) solution of 80Li2S•20P2S5 (mol %) solid electrolyte. SEM and EDX analysis showed that the Li2S-P2S5 solid electrolyte was uniformly coated on LiCoO2 particles. The all-solid-state cell using the LiCoO2 particles coated with the solid electrolyte showed higher charge-discharge capacity than the cells using uncoated LiCoO2 particles.

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Composite materials including NiS active materials, sulfide-based solid electrolytes (SE), and conductive additives (VGCF: vapor grown carbon fiber) were prepared by coating a highly conductive Li(2)S-P(2)S(5) solid electrolyte onto NiS-VGCF composite using pulsed laser deposition (PLD). From scanning electron microscopy, NiS nanoparticles were on VGCF surface after coating of solid electrolytes using PLD. All-solid-state cells using the SE-coated NiS-VGCF composite and the uncoated NiS-VGCF composite were fabricated, and then the coating effects on the electrochemical performance by forming the SE thin film onto the NiS-VGCF composite were investigated. At a high current density of 3.8 mA cm(-2) (corresponding to ca. 1 C), an all-solid-state cell fabricated using the SE-coated NiS-VGCF composite as a working electrode showed the initial discharge capacity of 300 mA h g(-1), and exhibited better cycle performance than the cell using the uncoated NiS-VGCF composite.