Provided is a sulfide solid electrolyte material which has a composition that does not contain Ge, while having a smaller Li content than conventional sulfide solid electrolyte materials, and which has both lithium ion conductivity and chemical stability at the same time. A sulfide solid electrolyte which has a crystal structure represented by composition formula (Li.sub.3.45+β−4αSn.sub.α)(Si.sub.0.36Sn.sub.0.09)(P.sub.0.55−βSi.sub.β)S.sub.4 (wherein α≤0.67, β≤0.33 and 0.43<α+β (provided that 0.23<α≤0.4 when β=0.2 and 0.13<α≤0.4 when β=0.3 may be excluded)), or a crystal structure represented by composition formula Li.sub.7+γSi.sub.γP.sub.1−γS.sub.6 (wherein 0.1≤γ<0.3).

A method of producing a solid electrolyte having a high ionic conductivity, which adopts a liquid-phase method and suppresses the generation of hydrogen sulfide, wherein a raw material inclusion containing a lithium element, a sulfur element, a phosphorus element, and a halogen element is mixed with a complexing agent containing a compound having at least two tertiary amino groups; and an electrolyte precursor constituted of a lithium element, a sulfur element, a phosphorus element, a halogen element, and a complexing agent containing a compound having at least two tertiary amino groups.

Disclosed herein is a solid electrolyte, comprising a compound of the formula A.sub.y(MS.sub.4).sub.z(PS.sub.4).sub.4-zX.sub.3, wherein the compound does not consist of Li.sub.15(PS.sub.4).sub.4CI.sub.3, and wherein the solid electrolyte presents an ionic conductivity of from 10.sup.−7 to 10.sup.−3 S/cm at room temperature. Also disclosed herein are methods of making a solid electrolyte.

A solid electrolyte for an all-solid-state sodium battery, represented by formula: Na.sub.3−xSb.sub.1−xα.sub.xS.sub.4, wherein α is selected from elements that provide Na.sub.3−xSb.sub.1−xα.sub.xS.sub.4 exhibiting a higher ionic conductivity than Na.sub.3SbS.sub.4, and x is 0<x<1.

A sulfide solid electrolyte is capable of suppressing a decrease in Li ion conductivity due to moisture. A sulfide solid electrolyte includes a Li element, a P element, a S element and an O element, and having a granular shape, and including a crystal portion oriented along the granular shape, on an inner surface of the sulfide solid electrolyte.

A coated particle including a sulfide-based particle and a fluorine-containing polymer that coats a surface of the sulfide-based particle. The fluorine-containing polymer includes a structural unit (1) based on a monomer (1) represented by the following formula (1) and a structural unit (2) based on at least one selected from the group consisting of, for example, a monomer (2) represented by the following formula (2):

##STR00001##

wherein, for example, X is a hydrogen atom; Y is a direct bond; and Rf is a C1-C10 linear or branched fluoroalkyl group,

##STR00002##

wherein, for example, R.sup.1 is a hydrogen atom; and R.sup.2 is a hydrocarbon group. Also disclosed are positive and negative electrodes including the coated particle, an all-solid-state battery including the positive and negative electrodes and a coating composition for a sulfide-based all-solid-state battery.

An insulated wire includes a conductor including a copper material, and an insulation layer that is formed on an outer periphery of the conductor. A restoring temperature T.sub.B of the conductor is not more than 130° C. The restoring temperature T.sub.B is a temperature that is needed to restore a conductivity of the conductor after a coil processing to a conductivity of the conductor before the coil processing.

An insulated wire includes a conductor including a copper material, and an insulation layer that is formed on an outer periphery of the conductor. A restoring temperature T.sub.B of the conductor is not more than 130° C. The restoring temperature T.sub.B is a temperature that is needed to restore a conductivity of the conductor after a coil processing to a conductivity of the conductor before the coil processing.

A method of producing a solid electrolyte having a high ionic conductivity, which adopts a liquid-phase method and suppresses the generation of hydrogen sulfide, wherein a raw material inclusion containing a lithium element, a sulfur element, a phosphorus element, and a halogen element is mixed with a complexing agent containing a compound having at least two tertiary amino groups; and an electrolyte precursor constituted of a lithium element, a sulfur element, a phosphorus element, a halogen element, and a complexing agent containing a compound having at least two tertiary amino groups.

A solid electrolyte contains aluminum in an amount of 100 to 1000 ppm, inclusive, on a mass basis, and has lithium ion conductivity. It is preferable that aluminum is derived from an oxide of aluminum. It is also preferable that the solid electrolyte is a sulfide solid electrolyte containing a lithium element, a phosphorus element, and a sulfur element. It is also preferable that the solid electrolyte has an argyrodite-type crystal structure. It is also preferable that the solid electrolyte has a lithium ion conductivity of 4.0 mS/cm or greater.