Sulfide solid electrolyte and all solid state battery

1. A sulfide solid electrolyte comprising a Li element, a P element, a S element and an O element,

wherein the sulfide solid electrolyte has a granular shape,

the sulfide solid electrolyte includes a crystal portion oriented along the granular shape, on an inner surface of the sulfide solid electrolyte,

the sulfide solid electrolyte has a composition represented by Li 3+x PS 4−y O y , wherein x satisfies 0≤x≤1, and y satisfies 0<y<4;

a thickness of the crystal portion is 1.7 nm or more, and

the crystal portion includes an LGPS type crystal phase.

2. The sulfide solid electrolyte according to claim 1 , wherein the x satisfies 0≤x≤0.2, and the y satisfies 0.8≤y≤1.2.

3. An all solid state battery comprising a cathode active material layer including a cathode active material, an anode active material layer including an anode active material, and a solid electrolyte layer formed between the cathode active material layer and the anode active material layer, and

at least one of the cathode active material layer, the anode active material layer, and the solid electrolyte layer includes the sulfide solid electrolyte according to claim 1 .

4. The sulfide solid electrolyte according to claim 1 , wherein among all surface regions of the sulfide solid electrolyte, the proportion of the region where the crystal portion is formed is 90% or more.

5. The sulfide solid electrolyte according to claim 1 , wherein the sulfide solid electrolyte includes a midportion located at an inner side of the crystal portion, and

the midportion includes the same crystal phase as the crystal portion.

6. The sulfide solid electrolyte according to claim 1 , wherein x satisfies 0<x≤0.5.