Negative electrode material and battery
The present disclosure provides a negative electrode material that can improve the charge-discharge efficiency of a battery. A negative electrode material includes a reduced form of a first solid electrolyte material and a conductive auxiliary. The first solid electrolyte material is denoted by Formula (1): Li 60 M β X γ . Herein, in Formula (1), each of α, β, and γ is a value greater than 0, M represents at least one element selected from the group consisting of metal elements except Li and semimetals, and X represents at least one element selected from the group consisting of F, Cl, Br, and I.
1. A negative electrode material comprising a reduced form of a first solid electrolyte material and a conductive auxiliary,
wherein the first solid electrolyte material is denoted by Formula (1) below,
Li α M β X γ Formula (1)
herein, in Formula (1),
each of α, β, and γ is a value greater than 0,
M represents at least one element selected from the group consisting of metal elements except Li and semimetals, and
X represents at least one element selected from the group consisting of F, Cl, Br, and I.
2. The negative electrode material according to claim 1 ,
wherein a peak top is present at the value of the diffraction angle 2θ within the range of greater than θa and less than or equal to θb in an X-ray diffraction pattern of the reduced form obtained by X-ray diffraction measurement in which the Cu-Kα ray is used as a radiation source,
θb is a value of the diffraction angle 2θ of the peak top of a peak reflecting the (220) face of LiX composed of Li and X, and
θa is a value of the diffraction angle 2θ of the peak top of a peak derived from the first solid electrolyte material, which is not reduced, and is a value closest to θb.
3. The negative electrode material according to claim 1 ,
wherein the first solid electrolyte material satisfies
1.5≤α≤4.5,
0.5≤β≤1.5, and
γ=6.
4. The negative electrode material according to claim 1 ,
wherein the first solid electrolyte material satisfies the relationship represented by
α+ mβ=γ
herein m represents the valence of M above.
5. The negative electrode material according to claim 1 ,
wherein M contains at least one element selected from the group consisting of transition metal elements.
6. The negative electrode material according to claim 5 , wherein M contains yttrium.
7. The negative electrode material according to claim 6 ,
wherein the first solid electrolyte material is denoted by Formula (2) below,
Li a Me b Y c X 6 Formula (2)
herein, in Formula (2) above,
a, b, and c satisfy a+m e b+3c=6 and c>0,
Me represents at least one element selected from the group consisting of metal elements except Li and Y and semimetals, and
m e represents the valence of Me above.
8. The negative electrode material according to claim 1 , wherein the conductive auxiliary contains acetylene black.
9. A negative electrode material comprising a reduced form of a first solid electrolyte material, a conductive auxiliary and a second solid electrolyte material,
wherein the first solid electrolyte material is denoted by Formula (1) below,
Li α M β X γ Formula (1)
wherein, in Formula (1),
each of α, β, and γ is a value greater than 0,
M represents at least one element selected from the group consisting of metal elements except Li and semimetals, and
X represents at least one element selected from the group consisting of F, Cl, Br, and I,
the reduction potential of the second solid electrolyte material with respect to lithium is lower than the reduction potential of the first solid electrolyte material with respect to lithium.
10. The negative electrode material according to claim 9 , wherein the second solid electrolyte material contains a sulfide solid electrolyte material.
11. The negative electrode material according to claim 10 , wherein the sulfide solid electrolyte material contains Li 2 S—P 2 S 5 .
12. A battery comprising:
a negative electrode containing a negative electrode material according to claim 1 ;
a positive electrode; and
an electrolyte layer disposed between the negative electrode and the positive electrode.
13. The negative electrode material according to claim 9 ,
wherein an amount of the reduced form of the first solid electrolyte material in the negative electrode material is 30 mass % or more.
14. The negative electrode material according to claim 13 , wherein 30≤v≤95 is satisfied, where v represents a volume ratio of the reduced form of the first solid electrolyte material with respect to a total volume of the reduced form of the first solid electrolyte material and the second solid electrolyte material.
15. The negative electrode material according to claim 9 ,
wherein an amount of the second solid electrolyte material is 70 mass % of less.
16. The negative electrode material according to claim 1 , wherein Li is occluded in the reduced form of the first solid electrolyte material.
17. The negative electrode material according to claim 1 , wherein an amount of the reduced form of the first solid electrolyte material in the negative electrode material is 80 mass % or more.
18. A battery comprising:
a negative electrode containing the negative electrode material according to claim 9 ;
a positive electrode; and
an electrolyte layer disposed between the negative electrode and the positive electrode.
19. The negative electrode material according to claim 1 , wherein the negative electrode material consists essentially of the reduced form of the first solid electrolyte material and the conductive auxiliary.
20. The negative electrode material according to claim 9 , wherein the negative electrode material consists essentially of the reduced form of the first solid electrolyte material, the conductive auxiliary and the second solid electrolyte material.