Lithium ion battery, negative electrode for lithium ion battery, battery module automobile, and power storage device
An object is to provide a lithium ion battery excellent in input/output characteristics, cycle life characteristics, and safety. The lithium ion battery is a lithium ion battery including, in a battery container, an electrolyte solution and an electrode group in which a positive electrode and a negative electrode are disposed through a separator. A lithium-nickel-manganese-cobalt composite oxide having a layered crystal structure is contained as a positive electrode active material, an easily graphitizable carbon is contained as a negative electrode active material, a weight of the easily graphitizable carbon heated at 550° C. in dry air flow in thermogravimetric analysis is equal to more than 75% of a weight of the easily graphitizable carbon heated at 25° C. therein, and a weight of the easily graphitizable carbon heated at 650° C. therein is equal to or less than 20% of the weight of the easily graphitizable carbon heated at 25° C. therein.
1. A lithium ion battery comprising, in a battery container:
an electrode group in which a positive electrode and a negative electrode are disposed through a separator; and
an electrolyte solution,
wherein a lithium-nickel-manganese-cobalt composite oxide having a layered crystal structure is contained as a positive electrode active material,
an easily graphitizable carbon is contained as a negative electrode active material,
a weight of the negative electrode active material heated at 550° C. in dry air flow in thermogravimetric analysis is equal to more than 75% of a weight of the negative electrode active material heated at 25° C. therein, and
a weight of the negative electrode active material heated at 650° C. in dry air flow in thermogravimetric analysis is equal to or less than 20% of the weight of the negative electrode active material heated at 25° C. therein.
2. The lithium ion battery according to claim 1 ,
wherein, in the easily graphitizable carbon, a median particle diameter (d50) on volumetric basis as measured with a laser diffraction particle size distribution meter is from 5 μm to 30 μm, a specific surface area as obtained by a nitrogen adsorption measurement method is from 1.0 m2/g to 5.0 m2/g, and a carbon dioxide adsorption amount until a relative pressure of 0.03 (at 273 K) is from 0.01 cm3/g to 4.0 cm3/g.
3. The lithium ion battery according to claim 2 ,
wherein the specific surface area as obtained by the nitrogen adsorption measurement method is from 1.3 m2/g to 4.0 m2/g.
4. The lithium ion battery according to claim 2 ,
wherein the carbon dioxide adsorption amount until the relative pressure of 0.03 (at 273 K) is from 0.05 cm3/g to 1.5 cm3/g.
5. A negative electrode for a lithium ion battery,
wherein an easily graphitizable carbon is contained as a negative electrode active material,
a weight of the negative electrode active material heated at 550° C. in dry air flow in thermogravimetric analysis is equal to or more than 75% of a weight of the negative electrode active material heated at 25° C. therein, and
a weight of the negative electrode active material heated at 650° C. therein is equal to or less than 20% of the weight of the negative electrode active material heated at 25° C. therein.
6. A lithium ion battery comprising a negative electrode for the lithium ion battery according to claim 5 .
7. A battery module configured by collecting a plurality of the lithium ion batteries according to claim 1 .
8. An automobile on which the battery module according to claim 7 is mounted.
9. A power storage device on which the battery module according to claim 7 is mounted.