Composite graphite material, method for preparing same, negative electrode sheet, secondary battery, battery module, battery pack, and electrical apparatus
View Patent ↗Disclosed are a composite graphite material, a method for preparing the same, a negative electrode sheet, a secondary battery, a battery module, a battery pack, and an electrical apparatus. The composite graphite material comprises a bulk particle and a cladding layer located on at least a partial surface of the bulk particle, the bulk particle is a secondary particle formed by aggregation of more than two primary particles, the bulk particle comprises artificial graphite, the cladding layer comprises amorphous carbon, and an air oxidation temperature T 0 of the composite graphite material is from 630° C. to 730° C. The composite graphite material in the present application can enable the secondary battery to not only have a high energy density, but also have significantly improved fast charging performance and low-temperature power performance.
1 . A composite graphite material, comprising a bulk particle and a cladding layer located on at least a partial surface of the bulk particle, and a kinetic carbon material, wherein the bulk particle is a secondary particle formed by aggregation of more than two primary particles, the bulk particle comprises artificial graphite, the kinetic carbon material is located at an interface between the primary particles and/or in the cladding layer, the kinetic carbon material is obtained by graphitization of a raw material selected from one or more of hard carbon micro-expanded graphite, expanded graphite, or graphene, an interlayer distance d 002 between crystal planes of the raw material ( 002 ) of the kinetic carbon material is greater than or equal to 0.3358 nm, and the cladding layer comprises amorphous carbon,
wherein,
an air oxidation temperature To of the composite graphite material is from 630° C. to 730° C., and
the air oxidation temperature To is a temperature corresponding to an intersection of two tangents at two points corresponding to 500° C. and a temperature T 1 respectively on a thermogravimetric curve of the composite graphite material, the temperature T 1 is a peak temperature of a peak with a largest area in a differential thermogravimetric curve of the composite graphite material, and the thermogravimetric curve and the differential thermogravimetric curve is obtained by thermogravimetric analysis under following conditions: sample mass: 10±0.05 mg, purge gas: air at a gas flow rate of 60 mL/min, heating rate: 5° C./min, and a test temperature ranging from 35° C. to 950° C.
2 . The composite graphite material according to claim 1 , wherein the interlayer distance d 002 between crystal planes of the raw material ( 002 ) of the kinetic carbon material is from 0.3359 nm to 0.3366 nm.
3 . The composite graphite material according to claim 1 , wherein
the interlayer distance d 002 between the crystal planes of the composite graphite material ( 002 ) is from 0.3355 nm to 0.3364 nm;
a volume average particle size Dv50 of the composite graphite material is from 8.5 μm to 14.5 μm;
a volume average particle size Dv50 of the bulk particle is from 7.5 μm to 13.5 μm; and/or
a powder compaction density of the composite graphite material under a force of 20,000N is from 1.45g/cm 3 to 1.75g/cm 3 .
4 . The composite graphite material according to claim 1 , wherein a ratio of a volume average particle size Dv50 of the primary particles to a volume average particle size Dv50 of the secondary particle formed by the primary particles is from 0.45 to 0.75, and is optionally from 0.55 to 0.65.
5 . The composite graphite material according to claim 1 , wherein, based on the total mass of the composite graphite material, a percentage mass content of the amorphous carbon in the cladding layer is from 2% to 5%.
6 . A negative electrode sheet, comprising a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises the composite graphite material according to claim 1 .
7 . A secondary battery, comprising the negative electrode sheet according to claim 6 .
8 . A battery module, comprising the secondary battery according to claim 7 .
9 . A battery pack, comprising one of the secondary batteries according to claim 7 .
10 . An electrical apparatus, comprising at least one of the secondary batteries according to claim 7 .
11 . The composite graphite material according to claim 1 , wherein, a percentage mass content of the kinetic carbon material is from 1% to 30%, based on a total mass of the composite graphite material.
12 . The composite graphite material according to claim 1 , wherein, a percentage mass content of the kinetic carbon material is from 8% to 15%, based on a total mass of the composite graphite material.
13 . The composite graphite material according to claim 1 , wherein the raw material of the kinetic carbon material is selected from one or more of micro-expanded graphite, expanded graphite, and graphene.
14 . The composite graphite material according to claim 13 , wherein the raw material of the kinetic carbon material is graphene.