COMPOSITE ACTIVE MATERIAL
A composite active material of the present invention includes an active material and a surface portion located on the surface of the active material and containing a sulfur-containing compound. The active material contains a complex oxide containing a lithium (Li) element, a manganese (Mn) element, and an oxygen (O) element and having a spinel-type crystal structure. The active material preferably contains an element M1 (e.g., nickel) and an element M2 (e.g., titanium and aluminum). The complex oxide is also preferably represented by Li 1+x (M1 y M2 z Mn 2−x−y−z )O 4−δ , where 0≤x≤0.20, 0.20≤y≤1.20, 0≤z≤0.5, and 0≤δ≤0.2.
1 . A composite active material comprising:
an active material; and
a surface portion located on a surface of the active material and comprising a sulfur-containing compound,
wherein the active material comprises a complex oxide containing a lithium (Li) element, a manganese (Mn) element, and an oxygen (O) element and having a spinel-type crystal structure.
2 . The composite active material according to claim 1 , wherein the active material contains an element M1 and an element M2,
wherein M1 is one or a combination of two or more selected from the group consisting of a nickel (Ni) element, a cobalt (Co) element, and an iron (Fe) element, and
M2 is one or a combination of two or more selected from the group consisting of a sodium (Na) element, a magnesium (Mg) element, an aluminum (Al) element, a phosphorus (P) element, a potassium (K) element, a calcium (Ca) element, a titanium (Ti) element, a vanadium (V) element, a chromium (Cr) element, a copper (Cu) element, a gallium (Ga) element, an yttrium (Y) element, a zirconium (Zr) element, a niobium (Nb) element, a molybdenum (Mo) element, an indium (In) element, a tantalum (Ta) element, a tungsten (W) element, a rhenium (Re) element, and a cerium (Ce) element.
3 . The composite active material according to claim 2 , wherein the complex oxide is represented by formula (1) below:
Li 1+x (M1 y M2 z Mn 2−x−y−z )O 4−δ (1)
wherein 0≤x≤0.20, 0.20≤y≤1.20, 0≤z≤0.5, and 0≤δ≤0.2.
4 . The composite active material according to claim 1 , wherein the complex oxide is represented by formula (2) below:
Li 1+x (Ni y M z Mn 2−x−y−z )O 4−δ (2)
wherein 0≤x≤0.20, 0.20≤y≤0.70, 0≤z≤0.5, and 0≤δ≤0.2, and M is one element or a combination of two or more elements selected from the group consisting of Na, Mg, Al, P, K, Ca, Ti, V, Cr, Fe, Co, Cu, Ga, Y, Zr, Nb, Mo, In, Ta, W, Re, and Ce.
5 . The composite active material according to claim 1 or 2 , wherein the active material comprises a core particle and a coating portion located on a surface of the core particle.
6 . The composite active material according to claim 5 , wherein the coating portion comprises a lithium (Li) element, an element A, and an oxygen (O) element,
wherein the element A is at least one selected from the group consisting of a titanium (Ti) element, a zirconium (Zr) element, a tantalum (Ta) element, a niobium (Nb) element, and an aluminum (Al) element.
7 . The composite active material according to claim 1 or 2 , wherein a coverage of the active material by the surface portion is 60% or more.
8 . The composite active material according to claim 1 or 2 , wherein the surface portion has a thickness of more than 0 nm and 500 nm or less.
9 . The composite active material according to claim 1 or 2 , wherein the sulfur-containing compound comprises a lithium (Li) element, a phosphorus (P) element, a sulfur(S) element, and a halogen (X) element.
10 . The composite active material according to claim 9 , wherein an atomic ratio of the halogen (X) element to the phosphorus (P) element, X/P, is more than 1.0.
11 . The composite active material according to claim 9 , wherein the halogen (X) element comprises at least a bromine (Br) element.
12 . The composite active material according to claim 9 ,
wherein the halogen (X) element comprises at least a chlorine (Cl) element and a bromine (Br) element, and
an atomic ratio of the total of the chlorine (Cl) element and the bromine (Br) element to the phosphorus (P) element, (Cl+Br)/P, is more than 1.0.
13 . The composite active material according to claim 1 or 2 , wherein the sulfur-containing compound comprises a crystalline phase having an argyrodite-type crystal structure.
14 . An electrode material mixture comprising the composite active material according to claim 1 or 2 , a solid electrolyte, and an electric conductive material.
15 . The electrode material mixture according to claim 14 , wherein the solid electrolyte is a material different from the sulfur-containing compound.
16 . A coating composition comprising the electrode material mixture according to claim 14 , a binder, and a solvent.
17 . An electrode comprising the electrode material mixture according to claim 14 and a binder.
18 . A battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer,
wherein the positive electrode layer comprises the composite active material according to claim 1 or 2 .
19 . The battery according to claim 18 ,
wherein the solid electrolyte layer comprises a solid electrolyte, and
the solid electrolyte is a different material from the sulfur-containing compound.