Solid ion conductor, solid electrolyte including the solid ion conductor, electrochemical cell including the solid ion conductor, and preparation method of the same
A compound represented by the Formula 1 and having an argyrodite-type crystal structure: Li a M1 x M2 w PS y M3 z Formula 1 wherein M1 is at least one element of Group 2 or Group 11 of the periodic table, M2 is at least one metal element other than Li of Group 1 of the periodic table, 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, and 0≤z≤2.
1. 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 a compound 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, in Formula 2,
M1 is at least one element of Group 2 or Group 11 of the periodic table,
M3 is at least one element of Group 17 of the periodic table, and
wherein 0<x<0.1, and 1<z≤2, and
wherein M1 is a monovalent cation or a divalent cation.
2. The electrochemical cell of claim 1 , wherein, in a compound of Formula 2, M1 is at least one of Cu, Ag, or Mg, or
wherein M3 is at least one of F, Cl, Br, or I.
3. The electrochemical cell of claim 1 , wherein the compound 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<0.05.
4. The electrochemical cell of claim 1 , wherein the compound 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.
5. A compound 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 or a divalent cation,
M3 is at least one element of Group 17 of the periodic table, and M3 is a monovalent anion, and
wherein 0<b≤0.01 and 0≤z≤2.
6. The compound of claim 5 , wherein the compound 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.
7. The compound of claim 5 , wherein the compound 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 Mgb) 7-z PS 6-z I z .
8. A compound represented by Formula 4:
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 or a divalent 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<0.1, 0≤w<0.1, 0<x+w<0.1, and 0≤z≤2.
9. The compound of claim 8 , wherein the compound 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 or K.
10. The compound of claim 8 , wherein the compound 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. A compound 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 or a divalent 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<0.02, 0<c<0.02, 0<b+c<0.02, and 0≤z≤2.
12. The compound of claim 11 , wherein the compound 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 Formula 5e
(Li 1-b-c Mg b K c ) 7-z PS 6-z M3 z Formula 5e
wherein, M3 is at least one of F − , Cl − , Br − , or I.
13. The compound of claim 11 , wherein the compound represented by Formula 1 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 0<b<0.01, 0<c<0.01, 0<b+c≤0.01, and 0<z≤2.
14. The electrochemical cell of claim 1 , wherein the compound represented by Formula 1 has an ion conductivity of 0.5 millisiemens per centimeter or greater at 25° C.
15. The electrochemical cell of claim 1 , wherein the compound represented by Formula 1 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 after 10 Days/Initial Ion Conductivity]×100%. Equation 1
16. The electrochemical cell of claim 1 , wherein the compound represented by Formula 1 belongs to a cubic crystal system, or wherein the compound represented by Formula 1 belongs to an F-43m space group.
17. The electrochemical cell of claim 1 , wherein a peak intensity ratio la/lb, 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, or
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.