Negative electrode active material of lithium secondary battery, negative electrode of lithium secondary battery, lithium secondary battery for vehicle installation using the negative electrode active material and negative electrode, and method for manufacturing the negative electrode active material
A negative electrode active material of lithium secondary battery include: at least one of a petroleum-derived green coke and a coal-derived green coke, and at least one of a petroleum-derived calcined coke and a coal-derived calcined coke within a mass ratio range of 90:10 to 10:90; a phosphorous compound within a range of 0.1 to 6.0 parts by mass in amount equivalent to phosphor relative to 100 parts by mass of the at least one of the green cokes and the at least one of the calcined cokes; and a boron compound within a range of 0.1 to 6.0 parts by mass in amount equivalent to boron relative to 100 parts by mass of the at least one of the green cokes and the at least one of the calcined cokes.
1. A negative electrode active material of lithium secondary battery, comprising:
coke comprising at least one green coke and at least one calcined coke, the green coke and the calcined coke being present in a mass ratio of 90:10 to 10:90, the green coke comprising one or more selected from the group consisting of a petroleum-derived green coke and a coal-derived green coke, and the calcined coke comprising one or more selected from the group consisting of a petroleum-derived calcined coke and a coal-derived calcined coke;
a phosphorous compound comprising phosphorous, the phosphorous and the coke being present in a ratio of 0.1:100 to 6.0:100 parts by mass; and
a boron compound comprising boron, the boron and the coke being present in a ratio of 0.1:100 to 6.0:100 parts by mass.
2. The negative electrode active material as set forth in claim 1 , wherein the green coke is a powdery green coke and the calcined coke is a powdery calcined coke.
3. The negative electrode active material as set forth in claim 1 , wherein the mass ratio of the green coke and the calcined coke is 70:30 to 30:70.
4. The negative electrode active material as set forth in claim 1 , wherein:
the ratio of phosphorous to coke is 0.5:100 to 5.0:100 parts by mass, and
the ratio of boron to coke is 0.5:100 to 5.0:100 parts by mass.
5. The negative electrode active material as set forth in claim 2 , wherein the powdery green coke has an average particle size of 5 to 15 μm.
6. The negative electrode active material as set forth in claim 2 , wherein the powdery green coke has a BET specific surface area of 5 m 2 /g or less.
7. The negative electrode active material as set forth in claim 1 , wherein the coke is fired with the phosphorous compound and the boron compound at a temperature of 800 to 1400° C.
8. The negative electrode active material as set forth in claim 1 , further comprising an output characteristic of 14 watts or more, an initial efficiency of 80% or more, and a capacity retention rate of 80% or more.
9. A lithium secondary battery comprising:
a negative electrode active material of lithium secondary battery as set forth in claim 1 , and
a binder for the negative electrode active material.
10. The lithium secondary battery as set forth in claim 9 , wherein the binder is at least one of polyvinylidene fluoride and polyimide.
11. The lithium secondary battery as set forth in claim 10 , wherein the binder is polyimide.
12. A secondary battery for vehicle installation comprising a negative electrode active material of lithium secondary battery as set forth in claim 1 .
13. A hybrid or electric vehicle comprising the lithium secondary battery as set forth in claim 11 .
14. A method for manufacturing a negative electrode active material of lithium secondary battery, comprising the steps of:
mixing at least one green coke and at least one calcined coke to produce a mixture of green coke and calcined coke, the mixture comprising a mass ratio of the green coke to the calcined coke of 90:10 to 10:90, the green coke comprising one or more selected from the group consisting of a petroleum-derived green coke and a coal-derived green coke, and the calcined coke comprising one or more selected from the group consisting of a petroleum-derived calcined coke and a coal-derived calcined coke;
adding a phosphorous compound and a boron compound to the mixture of green coke and calcined coke, the phosphorous compound comprising phosphorous, the phosphorous being added to the mixture of green coke and calcined coke in a ratio of 0.1:100 to 6.0:100 parts by mass, the boron compound comprising boron, the boron being added to the mixture of green coke and calcined coke in a ratio of 0.1:100 to 6.0:100; and
firing the mixture of the green coke and the calcined coke with the phosphorous compound and the boron compound.
15. The manufacturing method as set forth in claim 14 , wherein the green coke and the calcined coke are mixed in a mass ratio of 70:30 to 30:70.
16. The manufacturing method as set forth in claim 14 , further comprising the steps of: pulverizing the green coke and the calcined coke to make a powdery green coke and a powdery calcined coke before mixing the green coke and the calcined coke.
17. The manufacturing method as set forth in claim 14 ,
wherein the phosphorous is added to the mixture of green coke and calcined coke in a ratio 0.5:100 to 5.0:100 parts by mass,
wherein the boron is added to the mixture of green coke and calcined coke in a ratio of 0.5:100 to 5.0:100 parts by mass.
18. The manufacturing method as set forth in claim 14 ,
wherein the mixture of green coke and calcined coke with the phosphorous compound and the boron compound is fired at a temperature of 800 to 1400° C.