Positive active material and nonaqueous electrolyte secondary battery produced using the same
View Patent ↗A positive active material is composed of particles of a compound oxide of lithium and a transition metal. This compound oxide has a layered structure. A coating layer of an inorganic compound and a carbonaceous material is formed on at least part of each surface of the particles. The inorganic compound is a lithium compound. The weight ratio of the inorganic compound to the carbonaceous material ranges between 99:1 and 60:40. The weight ratio of the particles to the coating layers ranges between 98:2 and 70:30.
1. A positive active material comprising:
base particles comprising lithium-nickel-manganese oxide; and
a mixture consisting of an inorganic compound and a carbonaceous material on substantially the entire surface of the base particles;
wherein,
a weight ratio of the lithium-nickel-manganese oxide to the mixture is between 98:2 to 70:30 and is represented by the formula A:(B+C),
A is the weight of the lithium-nickel-manganese oxide,
B is the weight of the inorganic compound,
C is the weight of the carbonaceous material, and
the inorganic compound is a compound oxide of at least one selected from the group of LiFePO 4 and Li 3 PO 4 .
2. The positive active material according to claim 1 , wherein the weight ratio of the inorganic compound to the carbonaceous material ranges between 99:1 and 60:40.
3. A nonaqueous electrolyte secondary battery comprising:
a negative active material;
a positive active material comprising base particles that include lithium-nickel-manganese oxide;
a nonaqueous electrolyte between the negative and positive active materials; and
a mixture consisting of an inorganic compound and a carbonaceous material on substantially the entire surface of the base particles; and
wherein,
a weight ratio of the compound oxide to the mixture is between 98:2 to 70:30 and is represented by the formula A:(B+C),
A is the weight of the lithium-nickel-manganese oxide,
B is the weight of the inorganic compound,
C is the weight of the carbonaceous material, and
the inorganic compound is a compound oxide of at least one selected from the group of LiFePO 4 and Li 3 PO 4 .
4. The positive active material according to claim 3 , wherein the weight ratio of the inorganic compound to the carbonaceous material ranges between 99:1 and 60:40.