Solid-state battery
A solid-state battery that includes a negative electrode layer and a solid electrolyte layer. The negative electrode layer contains a negative electrode active material in which a molar ratio of Li to vanadium (V) is 2.0 or more, the solid electrolyte layer contains a solid electrolyte having a lithium super ionic conductor (LISICON)-type structure and containing at least V, and the solid electrolyte contained in the solid electrolyte layer has an average chemical composition represented by (Li [3−ax+(5−b)(1−y)] A x )(V y B 1−y )O 4 .
1 . A solid-state battery comprising:
a positive electrode layer;
a negative electrode layer; and
a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer,
wherein
the negative electrode layer contains a negative electrode active material in which a molar ratio of Li to vanadium (V) is 2.0 or more,
the solid electrolyte layer contains a solid electrolyte having a lithium super ionic conductor structure and containing at least V,
the solid electrolyte contained in the solid electrolyte layer has an average chemical composition represented by: (Li [3−ax+(5−b)(1−y)] A x )(V y B 1−y )O 4
where A is one or more elements selected from the group consisting of Na, K, Mg, Ca, Al, Ga, Zn, Fe, Cr, and Co,
B is one or more elements selected from the group consisting of Zn, Al, Ga, Si, Ge, Sn, P, As, Ti, Mo, W, Fe, Cr, and Co,
0≤x≤1.0,
0<y≤0.75,
[3−ax+(5−b)(1−y)]>0,
a is an average valence of A, and
b is an average valence of B,
the negative electrode active material has an average chemical composition represented by: (Li′ [3−a′x′+(5−b′)(1−y′)] A′ x′ )(V y B′ 1−y )O 4
where A′ is one or more elements selected from the group consisting of Na, K, Mg, Ca, Al, Ga, Zn, Fe, Cr, and Co,
B′ is one or more elements selected from the group consisting of Zn, Al, Ga, Si, Ge, Sn, P, As, Ti, Mo, W, Fe, Cr, and Co,
0≤x′≤1.0,
0.5≤y′≤1.0,
a′ is an average valence of A′, and
b′ is an average valence of B′
wherein the amount y of V in the solid electrolyte contained in the solid electrolyte layer is lower than the amount y′ of V′ in the negative electrode active material, and
a difference between y and y′ is greater than 0.4.
2 . The solid-state battery according to claim 1 , wherein, in the negative electrode active material:
A′ is one or more elements selected from the group consisting of Al and Zn,
B′ is one or more elements selected from the group consisting of Si and P, and
0≤x′≤0.06, and
0.55≤y′≤1.0.
3 . The solid-state battery according to claim 1 , wherein the negative electrode active material has a β II -Li 3 VO 4 -type structure or a γ II -Li 3 VO 4 -type structure.
4 . The solid-state battery according to claim 1 , wherein, in the solid electrolyte contained in the solid electrolyte layer, 0<y≤0.65.
5 . The solid-state battery according to claim 1 , wherein in the solid electrolyte contained in the solid electrolyte layer, 0.05≤y≤0.48.
6 . The solid-state battery according to claim 1 , wherein in the solid electrolyte contained in the solid electrolyte layer, 0.25≤y≤0.48.
7 . The solid-state battery according to claim 1 , wherein in the solid electrolyte contained in the solid electrolyte layer, 0≤x≤0.2.
8 . The solid-state battery according to claim 1 , wherein at least one of the negative electrode layer and the solid electrolyte layer further contains a solid electrolyte having a garnet-type structure.
9 . The solid-state battery according to claim 8 , wherein the solid electrolyte having a garnet-type structure has an average chemical composition represented by: (Li [7−a″x″−(b″−4)y″)] A″ x″ )La 3 Zr 2−y″ B″ y″ O 12
where A″ is one or more elements selected from the group consisting of Ga, Al, Mg, Zn, and Sc,
B″ is one or more elements selected from the group consisting of Nb, Ta, W, Te, Mo, and Bi,
0≤x″≤0.5,
0≤y″≤2.0,
a″ is an average valence of A″, and
b″ is an average valence of B″.
10 . The solid-state battery according to claim 9 , wherein, in the solid electrolyte having a garnet-type structure:
A″ is one or more elements selected from the group consisting of Ga and Al,
B″ is one or more elements selected from the group consisting of Nb, Ta, W, Mo, and Bi,
0.1≤x″≤0.3, and
0≤y″≤1.0.
11 . The solid-state battery according to claim 1 , wherein the negative electrode layer further contains a conductive additive.
12 . The solid-state battery according to claim 1 , wherein
at least one of the negative electrode layer and the solid electrolyte layer further contains a sintering additive, and
the sintering additive is a compound that has a chemical composition containing Li, boron, and O and in which a molar ratio of Li to boron is 2.0 or more.
13 . The solid-state battery according to claim 1 , wherein the solid electrolyte layer, the positive electrode layer, and the negative electrode layer are an integrally sintered body.
14 . The solid-state battery according to claim 1 , wherein the molar ratio of Li to vanadium (V) is 2 to 10.
15 . The solid-state battery according to claim 1 , wherein the molar ratio of Li to vanadium (V) is 2 to 6.
16 . The solid-state battery according to claim 1 , wherein, in the solid electrolyte contained in the solid electrolyte layer:
A is Al,
B is one or more elements selected from the group consisting of Si, Ge, and P, and
0≤x≤0.2.
17 . The solid-state battery according to claim 1 , wherein a volume ratio of the solid electrolyte in the solid electrolyte layer is 10% to 80%.
18 . The solid-state battery according to claim 1 , wherein the difference between y and y′ is 0.5 or greater.