CN-115621439-B - Composite material, preparation method thereof and secondary battery

CN115621439BCN 115621439 BCN115621439 BCN 115621439BCN-115621439-B

Abstract

The application relates to a composite material, a preparation method thereof and a secondary battery, wherein the composite material comprises carbon matrixes which are stacked, graphite particles are filled among carbon matrix sheets, and the ratio of D90 of the carbon matrixes to D90 of the graphite particles is more than or equal to 10. The carbon matrix laminated in the composite material has ultrahigh conductivity, can form a conductive path and improve the conductivity of the composite material, and graphite particles filled between carbon matrix sheets can increase conductive contact points and enhance the connectivity of the conductive path, and further the ratio of D90 of the carbon matrix to D90 of the graphite particles is more than or equal to 10, so that the carbon matrix sheets and the graphite particles can be fully contacted, the integrity of a conductive network is ensured, and the conductivity and the capacity of the composite material are further improved.

Inventors

ZHANG YAN
CUI JIAMING
WANG QIANLONG
LIN JINSHENG

Assignees

深瑞墨烯科技(福建)有限公司

Dates

Publication Date: 20260505
Application Date: 20220929

Claims (10)

1. The composite material is characterized by comprising carbon matrixes which are stacked, graphite particles are filled among sheets of the carbon matrixes, the ratio of D90 of the carbon matrixes to D90 of the graphite particles is 10.33-21.3, the D90 of the carbon matrixes is smaller than 10 mu m, the D90 of the graphite particles is smaller than 1 mu m, and the median particle diameter D50 of the carbon matrixes is smaller than 5 mu m.
2. The composite material of claim 1, wherein the composite material comprises at least one of the following features (1) - (6): (1) At least part of the surface of the carbon matrix is dispersed with the graphite particles; (2) The raw materials of the composite material comprise heat conducting film waste; (3) The raw materials of the composite material comprise heat conducting film waste, wherein the heat conducting film waste comprises at least one of graphene heat conducting films, natural graphite heat conducting films and artificial graphite heat conducting films; (4) The mass ratio of the graphite particles in the composite material is 0.1% -30%; (5) The carbon matrix comprises at least one of graphene and graphite; (6) The graphite particles have a median particle diameter D50 of less than 0.5 μm.
3. The composite material of claim 1, wherein the composite material comprises at least one of the following features (1) - (5): (1) The fixed carbon content of the composite material is greater than 99.9%; (2) The moisture content of the composite material is less than 0.1%; (3) The ash content of the composite material is less than 0.1%; (4) The composite material further comprises a doping element, wherein the mass ratio of the doping element in the composite material is 0 ppm-0.2 ppm, and the doping element comprises at least one of Fe, co, cu, ni, cr, zn and Mn; (5) The mass ratio of the sulfur element in the composite material is less than or equal to 100ppm.
4. The composite material of claim 1, wherein the composite material comprises at least one of the following features (1) - (5): (1) The graphitization degree of the composite material is more than or equal to 99%; (2) The median particle diameter D90 of the composite material is less than or equal to 10 mu m; (3) The powder compaction density of the composite material is 1.75 g/cm 3 ~1.85g/cm 3 ; (4) The tap density of the composite material is 0.08 g/cm 3 ~0.18 g/cm 3 ; (5) The powder conductivity of the composite material is more than or equal to 300S/cm.
5. A method for preparing the composite material according to any one of claims 1 to 4, comprising the steps of: Carbonizing the waste heat conducting film to obtain a first precursor, wherein carbonization is performed in a first protective atmosphere; graphitizing the first precursor to obtain a second precursor, wherein the carbonization temperature is less than or equal to the graphitization temperature; And crushing the second precursor to obtain the composite material.
6. The method according to claim 5, wherein the method comprises at least one of the following features (1) to (9): (1) The waste heat conducting film is derived from graphite heat conducting films; (2) The waste of the heat conducting film is derived from a graphite heat conducting film, and the components of the graphite heat conducting film comprise a base material, a graphite film and a polymer adhesive material; (3) The waste of the heat conducting film is derived from a graphite heat conducting film, and the graphite heat conducting film comprises at least one of a graphene heat conducting film, a natural graphite heat conducting film and an artificial graphite heat conducting film; (4) The first precursor comprises a mixture of a carbon matrix and amorphous carbon; (5) The first precursor comprises a mixture of a carbon matrix and amorphous carbon, wherein the carbon matrix comprises at least one of graphene and graphite; (6) The carbonization temperature is 900-1500 ℃; (7) The temperature rising rate of carbonization is 0.5-2 ℃ per minute; (8) The carbonization heat preservation time is 5-10 hours; (9) The first protective atmosphere includes at least one of nitrogen, helium, and argon.
7. The method according to claim 5, wherein the method comprises at least one of the following features (1) to (6): (1) The graphitization temperature is 2700-3000 ℃; (2) The temperature rising rate of graphitization is 0.5-3 ℃ per minute; (3) The heating time of graphitization is 20-50 h; (4) The graphitization heat preservation time is 5-10 hours; (5) The graphitizing is performed in a second protective atmosphere comprising at least one of nitrogen, helium, and argon; (6) The median particle diameter D90 of the composite material is less than or equal to 10 mu m.
8. The method of manufacturing according to claim 5, characterized in that the method comprises at least one of the following features: and carrying out first crushing and second crushing treatment on the second precursor to obtain the composite material.
9. The preparation method according to claim 8, wherein the preparation method comprises at least one of the following features (1) to (8): (1) The first comminution apparatus comprises a jet mill; (2) The pressure of the crushing cavity for the first crushing is 0.3-0.6 MPa; (3) The rotating speed of the classifying wheel for the first crushing is 5000 rpm-6500 rpm; (4) The induced air rotation speed of the first crushing is 2000 rpm-2500 rpm; (5) The second comminution apparatus comprises a jet mill; (6) The pressure of the second crushing cavity is 0.6-0.8 MPa; (7) The rotating speed of the classifying wheel for the second crushing is 6500 rpm-7500 rpm; (8) The induced air rotation speed of the second crushing is 2500 rpm-3000 rpm.
10. A secondary battery, characterized in that the secondary battery comprises the composite material according to any one of claims 1 to 4 or the composite material prepared by the preparation method according to any one of claims 5 to 9.

Description

Composite material, preparation method thereof and secondary battery Technical Field The application belongs to the technical field of energy storage materials, and particularly relates to a composite material, a preparation method and a secondary battery. Background The graphite heat conducting film is prepared through 7 steps of homogenizing and dispersing, coating and drying to form film, pre-treating, carbonizing, graphitizing, rolling and compacting and die cutting. In the die cutting process, in order to meet the requirements of space, use safety and durability of components, the films are cut and attached by adding high polymer-based double faced adhesive tape, a base material, a protective film and the like, and part of waste which cannot be used is inevitably generated in the die cutting process. Because the graphite die-cutting waste contains multiple components such as polymer gel materials, base materials, graphite films and the like, the treatment is difficult, and a great deal of waste is caused. At present, the carbonaceous anode material or the conductive agent is prepared by the prior art, the raw materials are required to be purchased and obtained, the structure is single, the formation of a conductive network is difficult, the conductivity and the capacity of the material are lower, and the cost is higher. Thus, there is an urgent need to provide a material that is inexpensive and has high conductivity and capacity. Disclosure of Invention In order to overcome the defects, the application provides a composite material, a preparation method thereof and a secondary battery, and the composite material can obtain a material with high conductivity and capacity and can be used in a negative electrode material or a conductive agent of the secondary battery. In a first aspect, the present application provides a composite material, the composite material including carbon substrates stacked, graphite particles filled between carbon substrate sheets, the ratio of D90 of the carbon substrates to D90 of the graphite particles being 10 or more. In some embodiments, the ratio of D90 of the carbon matrix to D90 of the graphite particles is 10 to 100. In some embodiments, at least a portion of the surface of the carbon matrix is dispersed with the graphite particles. In some embodiments, the feedstock of the composite material comprises thermally conductive film scrap. In some embodiments, the thermally conductive film waste comprises at least one of a graphene thermally conductive film, a natural graphite thermally conductive film, and an artificial graphite thermally conductive film. In some embodiments, the graphite particles comprise 0.1% -30% by mass of the composite material. In some embodiments, the carbon matrix comprises at least one of graphene and graphite. In some embodiments, the carbon matrix has a median particle diameter D50 of less than 5 μm. In some embodiments, the D90 of the carbon matrix is less than 10 μm. In some embodiments, the graphite particles have a median particle diameter D50 of less than 0.5 μm. In some embodiments, the D90 of the graphite particles is less than 1 μm. In some embodiments, the composite material has a fixed carbon content of greater than 99.9%. In some embodiments, the moisture content of the composite is less than 0.1%. In some embodiments, the ash content of the composite is less than 0.1%. In some embodiments, the composite material further comprises a doping element, wherein the doping element accounts for 0ppm to 0.2ppm of the composite material by mass, and the doping element comprises at least one of Fe, co, cu, ni, cr, zn and Mn. In some embodiments, the mass ratio of elemental sulfur in the composite is 100ppm or less. In some embodiments, the composite has a graphitization degree of 99% or more. In some embodiments, the median particle diameter D90 of the composite is 10 μm or less. In some embodiments, the composite material has a powder compaction density of 1.75g/cm 3～1.85g/cm3. In some embodiments, the composite material has a tap density of 0.08g/cm 3～0.18g/cm3. In some embodiments, the composite has a powder conductivity of 300S/cm or greater. In a second aspect, the present application provides a method of preparing a composite material, comprising the steps of: carbonizing the waste heat conducting film to obtain a first precursor, wherein carbonization is performed in a first protective atmosphere; graphitizing the first precursor to obtain a second precursor, wherein the carbonization temperature is less than or equal to the graphitization temperature; And crushing the second precursor to obtain the composite material. In some embodiments, the thermally conductive film waste is derived from a graphite-based thermally conductive film. In some embodiments, the thermal conductive film waste is derived from a graphite-based thermal conductive film, the components of which include a substrate, a graphite film, and a polymeric gum material. In