Solid ion conductor, solid electrolyte including the solid ion conductor, electrochemical cell including the solid ion conductor, and preparation method of the same

1. A compound of represented by Formula 2 and having an argyrodite-type crystal structure:

Li 7-x-z M1 x PS 6-z M3 z   Formula 2

wherein

M1 is at least one element of Group 2 or Group 11 of the periodic table, and M1 is a monovalent cation,

M3 is at least one element of Group 17 of the periodic table, and M3 is a monovalent anion, and

wherein 0<x<0.5 and 0≤z≤2.

2. The compound of claim 1 , wherein the compound represented by Formula 2 is represented by Formula 2a:

Li 7-x-z M1 x PS 6-z Cl z   Formula 2a

wherein

M1 is at least one of Cu, Ag, or Mg, and

wherein 0<x<0.5 and 1≤z≤2.

3. The compound of claim 1 , wherein the compound represented by Formula 2 is represented by Formula 2b:

Li 5.75-x M1 x PS 4.75 Cl 1.25   Formula 2b

wherein M1 is at least one of Cu, Ag, or Mg, and

wherein 0<x<0.05.

4. The compound of claim 1 , wherein the compound represented by Formula 2 is represented by Formula 3:

(Li 1-b M1 b ) 7-z PS 6-z M3 z   Formula 3

wherein,

M1 is at least one element of Group 2 or Group 11 of the periodic table, and M1 is a monovalent cation,

M3 is at least one element of Group 17 of the periodic table, and M3 is a monovalent anion, and

wherein 0<b≤0.06 and 0≤z≤2.

5. The compound of claim 4 , wherein the compound represented by Formula 3 is represented by Formula 3a, Formula 3b, or Formula 3c:

(Li 1-b Cu b ) 7-z PS 6-z M3 z   Formula 3a

(Li 1-b Ag b ) 7-z PS 6-z M3 z   Formula 3b

(Li 1-b Mg b ) 7-z PS 6-z M3 z ,  Formula 3c

wherein

M3 is at least one of F, Cl, Br, or I, and

wherein b and z are each apparently selected, and 0<b≤0.06 and 0≤z≤2.

6. The compound of claim 5 , wherein in each of Formula 3a, Formula 3b, and Formula 3c, b is independently selected and is 0<b<0.05.

7. The compound of claim 1 , wherein the compound represented by Formula 2 is represented by

(Li 1-b Cu b ) 7-z PS 6-z Cl z , (Li 1-b Ag b ) 7-z PS 6-z Cl z , (Li 1-b Mg b ) 7-z PS 6-z Cl z , (Li 1-b Cu b ) 7-z PS 6-z Br z , (Li 1-b Ag b ) 7-z PS 6-z Br z , (Li 1-b Mg b ) 7-z PS 6-z Br z , (Li 1-b Cu b ) 7-z PS 6-z I z , (Li 1-b Ag b ) 7-z PS 6-z I z , or (Li 1-b Mg b ) 7-z PS 6-z I z , and

wherein b and z are each independently selected and the conditions of 0<b≤0.05 and 0<z≤2.

8. A compound represented by Formula 4 and having an argyrodite-type crystal structure:

Li 7-x-w-z M1 x M2 w PS 6-z M3 z ,  Formula 4

wherein

M1 is at least one element of Group 2 or Group 11 of the periodic table, and M1 is a monovalent cation,

M2 is at least one metal element of Group 1 of the periodic table other than Li, and M1 is a monovalent cation,

M3 is at least one element of Group 17 of the periodic table, and M3 is a monovalent anion, and

wherein 0<x<0.5, 0≤w<0.5, 0<x+w<0.5, and 0≤z≤2.

9. The compound of claim 8 , wherein the compound represented by Formula 4 is represented by Formula 4a:

Li 7-x-w-z M1 x M2 w PS 6-z Cl z ,  Formula 4a

wherein

M1 is at least one of Cu, Ag, or Mg,

M2 is at least one of Na, K, and

wherein 0<x<0.5, 0<w<0.5, 0<x+w<0.5, and 1≤z≤2.

10. The compound of claim 8 , wherein the compound represented by Formula 4 is represented by Formula 4b:

Li 5.75-x-w M1 x M2 w PS 4.75 Cl 1.25   Formula 4b

wherein

M1 is at least one of Cu, Ag, or Mg,

M2 is at least one of Na or K, and

wherein 0<x<0.05, 0<w<0.05, and 0<x+w<0.05.

11. The compound of claim 8 , wherein the compound represented by Formula 4 is represented by Formula 5:

(Li 1-b-c M1 b M2 c ) 7-z PS 6-z M3 z   Formula 5

wherein

M1 is at least one element of Group 2 or Group 11 of the periodic table, and M1 is a monovalent cation,

M2 is at least one metal element of Group 1 of the periodic table and is other than Li, and M2 is a monovalent cation,

M3 is at least one element of Group 17 of the periodic table, and M3 is a monovalent anion, and

wherein 0<b<0.1, 0<c<0.1, 0<b+c≤0.1, and 0≤z≤2.

12. The compound of claim 11 , wherein the compound represented by Formula 5 is represented by Formula 5a, Formula 5b, Formula 5c, Formula 5d, Formula 5e, or Formula 5f:

(Li 1-b-c Cu b Na c ) 7-z PS 6-z M3 z ,  Formula 5a

(Li 1-b-c Ag b Na c ) 7-z PS 6-z M3 z ,  Formula 5b

(Li 1-b-c Mg b Na c ) 7-z PS 6-z M3 z ,  Formula 5c

(Li 1-b-c Cu b K c ) 7-z PS 6-z M3 z ,  Formula 5d

(Li 1-b-c Ag b K c ) 7-z PS 6-z M3 z , or  Formula 5e

(Li 1-b-c Mg b K c ) 7-z PS 6-z M3 z ,  Formula 5f

wherein,

M3 is at least one of F—, Cl—, Br—, or I—, and

wherein b, c, and z are independently selected and 0<b<0.1, 0<b+c≤0.1, and 0≤z≤2.

13. The compound of claim 12 , wherein the compound represented by Formula 5 is represented by:

(Li 1-b-c Cu b Na c ) 7-z PS 6-z Cl z , (Li 1-b-c Ag b Na c ) 7-z PS 6-z Cl z , (Li 1-b-c Mg b Na c ) 7-z PS 6-z Cl z , (Li 1-b-c Cu b K c ) 7-z PS 6-z Cl z , (Li 1-b-c Ag b K c ) 7-z PS 6-z Cl z , (Li 1-b-c Mg b K c ) 7-z PS 6-z Cl z , (Li 1-b-c Cu b Na c ) 7-z PS 6-z Br z , (Li 1-b-c Ag b Na c ) 7-z PS 6-z Br z , (Li 1-b-c Mg b Na c ) 7-z PS 6-z Br z , (Li 1-b-c Cu b K c ) 7-z PS 6-z Br z , (Li 1-b-c Ag b K c ) 7-z PS 6-z Br z , (Li 1-b-c Mg b K c ) 7-z PS 6-z Br z , (Li 1-b-c Cu b Na c ) 7-z PS 6-z I z , (Li 1-b-c Ag b Na c ) 7-z PS 6-z I z , (Li 1-b-c Mg b Na c ) 7-z PS 6-z I z , (Li 1-b-c Cu b K c ) 7-z PS 6-z I z , (Li 1-b-c Ag b K c ) 7-z PS 6-z I z , or (Li 1-b-c Mg b K c ) 7-z PS 6-z I z ,

wherein b, c, and z are each independently selected, and the conditions of 0<b<0.05, 0<c<0.05, 0<b+c≤0.05, and 0<z≤2.

14. A compound represented by Formula 6:

Li a M1 x M2 w PS y-p (SO 4 ) p M3 z   Formula 6

wherein

M1 is at least one element of Group 2 or Group 11 of the periodic table,

M2 is at least one metal element of Group 1 of the periodic table and is other than Li,

M3 is at least one element of Group 17 of the periodic table, and

wherein 4≤a≤8, 0<x<0.5, 0≤w<0.5, 3≤y≤7, 0<p<2, and 0≤z≤2.

15. The compound of claim 1 , wherein the compound represented by Formula 2 has an ion conductivity of 0.5 millisiemens per centimeter or greater at 25° C.

16. The compound of claim 1 , wherein the compound represented by Formula 2 has an ion conductivity of 1 millisiemens per centimeter or greater at 25° C.

17. The compound of claim 1 , wherein the compound represented by Formula 5 has an ion conductivity retention of 70% or more, after 10 days in an air atmosphere having a dew point of less than −60° C., wherein the ion conductivity retention is expressed by Equation 1:

Ionic Conductivity Retention=[Ion Conductivity of Solid Ion Conductor Compound after 10 Days Elapsed/Initial Ion Conductivity of Solid Ion Conductor Compound]×100%  Equation 1.

18. The compound of claim 1 , wherein the compound represented by Formula 2 belongs to a cubic crystal system.

19. The compound of claim 1 , wherein the compound represented by Formula 2 belongs to an F-43m space group.

20. The compound of claim 1 , wherein a peak intensity ratio Ia/Ib, which is ratio of a peak intensity at a diffraction angle of 46.0° 2θ±1.0° with respect to a peak intensity at a diffraction angle of 53.0° 2θ± 1 . 0 °, when the compound is analyzed by X-ray diffraction using CuKα radiation, is no more than 1.

21. The compound of claim 1 , wherein a full width at half maximum- of a peak at a diffraction angle of 46.0°2θ±1.0°2θ-, when the compound is analyzed by X-ray diffraction using CuKα radiation, is no more than 0.3°2θ.

22. A solid electrolyte comprising the compound of claim 1 .

23. An electrochemical cell comprising:

a cathode layer including a cathode active material layer;

an anode layer including an anode active material layer; and

an electrolyte layer arranged between the cathode layer and the anode layer, wherein

at least one of the cathode active material layer and the electrolyte layer comprises the compound of claim 1 .

24. The electrochemical cell of claim 23 , wherein the electrochemical cell is an all-solid secondary battery.

25. The electrochemical cell of claim 23 , wherein

the anode active material layer comprises an anode active material and a binder, and

the anode active material comprises an amorphous carbon and at least one of Au, Pt, Pd, Si, Ag, Al, Bi, Sn, or Zn.

26. The electrochemical cell of claim 25 , further comprising a metal layer located between an anode current collector and the anode active material layer, wherein the metal layer comprises lithium metal or a lithium alloy.

27. A method of preparing a solid ion conductor, the method comprising:

contacting a compound containing lithium, a compound containing an element of Group 2 or Group 11 of the periodic table, a compound containing phosphorous, and a compound containing an element of Group 17 of the periodic table to provide a mixture; and

heat-treating the mixture in an inert atmosphere to prepare the solid ion conductor, wherein the solid ion conductor comprises the compound of claim 1 .

28. The method of claim 27 , wherein the mixture further includes a compound having a metal element of Group 1 of the periodic table other than Li.

29. The method of claim 27 , wherein the heat-treating is performed at a temperature of about 400° C. to about 600° C. for about 1 hour to about 36 hours.

30. An electrochemical cell comprising:

a cathode layer including a cathode active material layer;

an anode layer including an anode active material layer; and

an electrolyte layer arranged between the cathode layer and the anode layer, wherein

at least one of the cathode active material layer and the electrolyte layer comprises the compound of claim 8 .

31. An electrochemical cell comprising:

a cathode layer including a cathode active material layer;

an anode layer including an anode active material layer; and

an electrolyte layer arranged between the cathode layer and the anode layer, wherein

at least one of the cathode active material layer and the electrolyte layer comprises the compound of claim 14 .