Solid electrolyte

1. A solid electrolyte, comprising:

an alkali metal element,

phosphorous,

sulfur, and

halogen,

wherein the solid electrolyte has a peak in a peak region of 75.0 ppm or more and 80.0 ppm or less in a 31 P-NMR spectrum.

2. The solid electrolyte according to claim 1 , wherein the solid electrolyte has a peak in a peak region of 86.0 ppm or more and 92.0 ppm or less in a 31 P-NMR spectrum.

3. The solid electrolyte according to claim 1 , wherein

the solid electrolyte has a first peak I 1 in a first peak region of 75.0 ppm or more and 80.0 ppm or less in the 31 P-NMR spectrum, and

an intensity ratio of a peak in a region other than the first peak region and a second peak region of 86.0 ppm or more and 92.0 ppm or less is 0.5 or less relative to the first peak I 1 .

4. The solid electrolyte according to claim 3 , wherein the solid electrolyte has a peak in the first peak region and a peak in the second peak region.

5. The solid electrolyte according to claim 4 , wherein an intensity ratio I 2 /I 1 of a second peak I 2 in the second peak region relative to the first peak I 1 is from 1 to 10.

6. The solid electrolyte according to claim 3 , wherein the alkali metal element is lithium and the halogen is Br.

7. The solid electrolyte according to claim 6 , wherein an intensity ratio I 2 /I 1 of a second peak I 2 in the second peak region relative to the first peak I 1 is 1 or more and 10 or less.

8. The solid electrolyte according to claim 6 , wherein an intensity ratio I c /I 1 of a peak I c appearing in regions other than the first peak region and the second peak region relative to the first peak I 1 is 0.25 or less.

9. The solid electrolyte according to claim 6 , wherein the solid electrolyte has an ionic conductivity of 5×10 −4 S/cm or more.

10. The solid electrolyte according to claim 6 , wherein the solid electrolyte has an average hydrogen sulfide concentration measured by a hydrolysis test of 200 ppm or less.

11. The solid electrolyte according to claim 6 , wherein the solid electrolyte has a crystalline structure.

12. The solid electrolyte according to claim 1 , wherein the solid electrolyte has a composition represented by the following formula (A′):

L a M b P c S d X e   (A′)

where L is an alkali metal; M is B, Al, Si, Ge, As, Se, Sn, Sb, Te, Pb or Bi or a combination thereof; X is I, Cl, Br or F or a combination thereof; and a, b, c, d and e satisfy 0<a≦12, 0≦b≦0.2, c=1, 0<d≦9 and 0<e≦9.

13. The solid electrolyte according to claim 12 , wherein b is 0.

14. The solid electrolyte according to claim 12 , wherein d is 4.

15. The solid electrolyte according to claim 12 , wherein X is I, Br or Cl.

16. The solid electrolyte according to claim 12 , wherein the solid electrolyte has a crystalline structure.

17. The solid electrolyte according to claim 12 , wherein

the solid electrolyte is amorphous, and

X is Br or Cl.

18. The solid electrolyte according to claim 12 , wherein the solid electrolyte is obtained from raw materials of lithium sulfide and phosphorous sulfide; sulfur and phosphorous; phosphorous sulfide and sulfur; or phosphorous sulfide, sulfur and phosphorous; and

a compound represented by formula (E′):

M w X x   (E′)

where M is Li, B, Al, Si, P, S, Ge, As, Se, Sn, Sb, Te, Pb or Bi; X is F, Cl, Br or I; and w is an integer of 1 or 2 and x is an integer of from 1 to 10.

19. The solid electrolyte according to claim 18 , wherein M is P and X is Br, I or Cl.

20. The solid electrolyte according to claim 18 , wherein M is Li and X is Br, I or Cl.

21. The solid electrolyte according to claim 12 , wherein the solid electrolyte is amorphous and has two crystallization peaks in a thermo gravimetric-differential thermal measurement.

22. The solid electrolyte according to claim 21 , wherein the two crystallization peaks appear in a range of 150° C. or higher and 360° C. or lower.

23. The solid electrolyte according to claim 21 , wherein a distance between the two crystallization peaks is 20 to 100° C.

24. The solid electrolyte according to claim 1 , wherein the alkali metal element is lithium.

25. The solid electrolyte according to claim 1 , wherein the solid electrolyte has an ionic conductivity of 5×10 −4 S/cm or more.

26. The solid electrolyte according to claim 1 , wherein the solid electrolyte has an average hydrogen sulfide concentration measured by a hydrolysis test of 200 ppm or less.

27. An electrolyte layer, comprising the solid electrolyte according to claim 1 .

28. A solid electrolyte obtained by a process comprising heating at a temperature of 150° C. or higher and 360° C. or lower the solid electrolyte according to claim 12 that is amorphous.

29. A solid electrolyte obtained by a process comprising heating the solid electrolyte according to claim 21 at a temperature between temperatures indicated by the two crystallization peaks.

30. A battery, comprising:

a cathode layer,

an electrolyte layer, and

an anode layer,

wherein at least one of the cathode layer, the electrolyte layer and the anode layer comprises the solid electrolyte according to claim 1 .