Solution and method for producing the same, and a method for producing active material for secondary battery
There is provided a solution containing lithium and at least one of a niobium complex and a titanium complex, excellent in storage stability, and suitable for forming a coating layer capable of improving battery characteristics of an active material, and a related technique, which is the solution containing lithium, at least one of a niobium complex and a titanium complex, and ammonia, wherein an amount of the ammonia in the solution is 0.2 mass % or less.
1. A solution containing lithium, a metal complex comprising at least one of a niobium complex and a titanium complex, and ammonia, wherein an amount of the ammonia in the solution is 0.2 mass % or less and 1 ppm or more.
2. The solution according to claim 1 , wherein the metal complex has a peroxy group.
3. The solution according to claim 2 , wherein a molar ratio of atoms in the lithium to atoms of a metal in the metal complex is 0.8 to 2.0.
4. The solution according to claim 1 , which further contains a reducing compound.
5. The solution according to claim 4 , wherein a ratio of the reducing compound in the solution is 0.01 mass % to 5.0 mass %.
6. The solution according to claim 1 , wherein the amount of the ammonia in the solution is 0.1 mass % or less and 1 ppm or more.
7. A method for producing an active material for a secondary battery, comprising:
performing a surface treatment using the solution of claim 1 ; and
heat-treating the surface-treated active material.
8. The method according to claim 7 , wherein the active material is an oxide containing lithium.
9. The method according to claim 7 , wherein the active material is an oxide containing lithium, and at least one of a lithium niobate compound and a lithium titanate compound is attached to a main surface of the active material.
10. A method for producing a solution, comprising:
forming a metal complex in a solution by mixing at least one of niobic acid and titanic acid with ammonia;
mixing the metal complex and a lithium compound in the solution; and
removing the ammonia in the mixed solution until an amount of the ammonia is reduced to 0.2 mass % or less and 1 ppm or more.