CN112978722A - Small-diameter graphene powder, graphene conductive paste, and preparation methods and applications thereof - Google Patents
Small-diameter graphene powder, graphene conductive paste, and preparation methods and applications thereof Download PDFInfo
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- CN112978722A CN112978722A CN201911302624.8A CN201911302624A CN112978722A CN 112978722 A CN112978722 A CN 112978722A CN 201911302624 A CN201911302624 A CN 201911302624A CN 112978722 A CN112978722 A CN 112978722A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 257
- 229910021389 graphene Inorganic materials 0.000 title claims abstract description 215
- 239000000843 powder Substances 0.000 title claims abstract description 76
- 238000002360 preparation method Methods 0.000 title claims abstract description 36
- 239000012530 fluid Substances 0.000 claims abstract description 40
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 33
- 239000010439 graphite Substances 0.000 claims abstract description 33
- 239000002002 slurry Substances 0.000 claims abstract description 25
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims description 28
- 239000002245 particle Substances 0.000 claims description 23
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- 238000004519 manufacturing process Methods 0.000 claims description 16
- 239000002904 solvent Substances 0.000 claims description 13
- 239000002994 raw material Substances 0.000 claims description 12
- 238000003756 stirring Methods 0.000 claims description 12
- 238000000265 homogenisation Methods 0.000 claims description 11
- 238000000498 ball milling Methods 0.000 claims description 8
- 238000010008 shearing Methods 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 6
- 239000002033 PVDF binder Substances 0.000 claims description 5
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 5
- GLUUGHFHXGJENI-UHFFFAOYSA-N Piperazine Chemical compound C1CNCCN1 GLUUGHFHXGJENI-UHFFFAOYSA-N 0.000 claims description 4
- VZGDMQKNWNREIO-UHFFFAOYSA-N carbon tetrachloride Substances ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 claims description 4
- 238000007873 sieving Methods 0.000 claims description 4
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 2
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 claims description 2
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 2
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 2
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 2
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 2
- 238000002525 ultrasonication Methods 0.000 claims description 2
- 239000006258 conductive agent Substances 0.000 abstract description 13
- 239000013543 active substance Substances 0.000 abstract description 10
- 230000008569 process Effects 0.000 abstract description 9
- 239000012071 phase Substances 0.000 abstract description 6
- 238000005507 spraying Methods 0.000 abstract description 6
- 238000005516 engineering process Methods 0.000 abstract description 5
- 239000007791 liquid phase Substances 0.000 abstract description 3
- 238000007709 nanocrystallization Methods 0.000 abstract description 3
- 239000002356 single layer Substances 0.000 description 17
- 239000010410 layer Substances 0.000 description 15
- 238000005056 compaction Methods 0.000 description 12
- 239000006185 dispersion Substances 0.000 description 10
- 239000000654 additive Substances 0.000 description 9
- 230000000996 additive effect Effects 0.000 description 9
- 238000001878 scanning electron micrograph Methods 0.000 description 9
- 230000002349 favourable effect Effects 0.000 description 8
- 239000011248 coating agent Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 7
- 239000010931 gold Substances 0.000 description 7
- 229910052737 gold Inorganic materials 0.000 description 7
- 238000002791 soaking Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 238000010587 phase diagram Methods 0.000 description 6
- 239000010406 cathode material Substances 0.000 description 5
- 238000011160 research Methods 0.000 description 5
- 230000002776 aggregation Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000002604 ultrasonography Methods 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
- SECXISVLQFMRJM-UHFFFAOYSA-N NMP Substances CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 3
- 239000011149 active material Substances 0.000 description 3
- 238000004220 aggregation Methods 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 239000002270 dispersing agent Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000004744 fabric Substances 0.000 description 3
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- 229910052744 lithium Inorganic materials 0.000 description 3
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- 239000007774 positive electrode material Substances 0.000 description 3
- 238000010298 pulverizing process Methods 0.000 description 3
- 238000004630 atomic force microscopy Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
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- 230000003044 adaptive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
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- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/182—Graphene
- C01B32/184—Preparation
- C01B32/19—Preparation by exfoliation
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/182—Graphene
- C01B32/194—After-treatment
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/60—Heating or cooling; Temperature control
- H01M10/62—Heating or cooling; Temperature control specially adapted for specific applications
- H01M10/625—Vehicles
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2204/00—Structure or properties of graphene
- C01B2204/04—Specific amount of layers or specific thickness
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2204/00—Structure or properties of graphene
- C01B2204/20—Graphene characterized by its properties
- C01B2204/32—Size or surface area
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
Abstract
The invention provides graphene powder which is obtained by spraying and stripping graphite through a supercritical fluid slit. According to the invention, by adopting a supercritical liquid phase narrow-hole stripping technology, graphene with small thickness and small sheet diameter can be prepared under the conditions of low cost and no pollution, and the graphene can be more favorably and uniformly dispersed in an oil phase or a water phase in the follow-up process to prepare the small-sheet-diameter graphene conductive slurry for the lithium ion battery. The small-particle-size graphene conductive paste provided by the invention can realize the nanocrystallization of graphene, improve the electronic conductivity as much as possible, reduce the ionic resistance, reduce the consumption of a conductive agent as much as possible, improve the consumption of active substances and increase the energy density of a battery on the premise of ensuring the performance of the battery. And the preparation method has low cost, mild condition, no pollution and easy control, and is more suitable for industrialized popularization and application.
Description
Technical Field
The invention belongs to the technical field of graphene, relates to graphene powder, graphene conductive paste, a preparation method and application thereof, and particularly relates to small-particle-size graphene powder, graphene conductive paste, a preparation method and application thereof.
Background
Graphene (Graphene) is a new material with a monolayer sheet structure composed of carbon atoms. It is a compound consisting of carbon atoms in sp2Hybrid railThe hexagonal honeycomb lattice planar film is formed of a two-dimensional material with a thickness of only one carbon atom. Since the graphene is prepared by Geim and the like in 2004 for the first time by adopting a micro-mechanical stripping method, the graphene attracts people's extensive attention because of excellent performances such as high conductivity, high specific surface area, high strength and high electron mobility, and further promotes the rapid development of the graphene preparation technology. Due to the excellent physicochemical properties, the material is widely applied to energy storage materials, environmental engineering and sensitive sensing, is called as 'black gold' or 'king of new materials', has a wide potential application prospect, and has become a focus and a research hotspot all over the world at present.
Along with the increasing environmental and energy problems, the research on lithium ion batteries is also becoming more intensive, and lithium ion batteries have the advantages of high specific energy, long cycle life, light weight and the like, so that the lithium ion batteries attract extensive attention and intensive research in various research institutions and industrial fields. At present, how to break through the technical bottleneck of the lithium ion battery, improve the energy density of the battery and prolong the endurance mileage becomes an important direction of international research. At present, the lithium iron phosphate battery is very close to the limit of energy density, a ternary cathode material with high energy density is in an explosion growth period, and how to optimize the energy density, safety and cycle life of the ternary battery on the existing basis is a problem to be solved urgently in the present stage.
Graphene has sp2The hybridized carbon six-membered ring two-dimensional crystal structure is a basic unit for constructing carbon materials with other dimensions. The single-layer graphene has a thickness of only 0.335nm, is the thinnest material in the world at present, and has the excellent performances of high conductivity, high specific surface area, high strength, high electron mobility and the like, so that the application prospect of the single-layer graphene in the field of lithium ion batteries is gradually concerned by the industry. However, although graphene has excellent performance, in practical application, graphene has many problems and restriction factors, and as for the preparation method thereof, graphene prepared by the existing physical stripping method is thick in sheet layer and not significant in graphene characteristic, and as an additive of a lithium ion battery, optimization is difficult to achieve under the condition of a small addition amountThe energy density of the ternary battery. Graphene prepared by redox has a thin sheet layer but poor conductivity, and the performance of the battery is seriously influenced. The laboratory-level CVD method is too complicated in preparation process, harsh in conditions, and difficult to realize large-scale industrial production, popularization and application, and the production efficiency is affected.
Therefore, how to find an adaptive graphene preparation method solves the technical problems existing in the existing preparation methods, obtains a graphene product more suitable for serving as a lithium ion additive, has a better industrialization prospect, and becomes one of the problems to be solved by many research and development enterprises and front-line researchers in the industry.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide a graphene powder, a graphene conductive paste, and a preparation method and an application thereof, and particularly to a preparation method of a small-diameter graphene powder. And the graphene conductive paste is used as a ternary cathode material. The conductivity of the anode material can be increased, the compaction density is improved, and the addition of active substances is increased under the condition of less addition, so that the energy density of the ternary battery is improved, and the preparation process is more suitable for industrial popularization and application.
The invention provides graphene powder which is obtained by spraying and stripping graphite through a supercritical fluid slit.
Preferably, the graphene is small-radius graphene;
the thickness of the graphene sheet layer is less than or equal to 10 layers;
the particle size of the graphene powder is 0.2-1 mu m;
the supercritical fluid comprises CO2Supercritical fluid, N2Supercritical fluid, C2H4Supercritical fluid and CCl4One or more of the supercritical fluids.
Preferably, the sheet diameter of the graphene is less than or equal to 1 μm;
the graphite comprises one or more of graphite powder, crystalline flake graphite, artificial graphite, expandable graphite and expanded graphite;
the length of the slit is 1-100 mm;
the width of the slit is 1 mu m-1 mm.
The invention provides graphene conductive slurry which comprises the following raw materials in parts by mass:
2-4 parts by weight of graphene powder according to any one of the above technical schemes;
0.5-1 part by weight of a binder;
95-97.5 parts by weight of a solvent.
Preferably, the binder comprises one or more of polyvinylidene fluoride, styrene butadiene rubber, piperazine, diethanolamine and polyvinylpyrrolidone;
the solvent comprises one or more of NMP, DMF and water.
The invention provides a preparation method of graphene conductive slurry, which comprises the following steps:
1) under the condition of closed pressure, immersing graphite into supercritical fluid for mixing to obtain supercritical state mixed liquor;
2) pressurizing the supercritical mixed solution obtained in the step, and then carrying out slit jet stripping to obtain graphene powder;
3) and mixing the graphene powder obtained in the step, the binder and the solvent again to obtain the graphene conductive slurry.
Preferably, the graphite comprises graphite powder subjected to homogenization treatment;
the homogenization treatment mode comprises one or more of sieving, ball milling, airflow crushing and crushing by a crusher;
the particle size of the graphite is 1-10 mu m.
Preferably, the mass ratio of the graphite to the supercritical fluid is 1: (100-500);
the pressure of the closed belt is 10-75 MPa;
the mixing time is 30-180 min;
the mixing temperature is 0-100 ℃;
the mixing mode comprises one or more of double-planet stirring, high-speed shearing, internal circulation, ultrasonic and vibration.
Preferably, the pressurizing pressure is 80-150 MPa;
the slit jet stripping temperature is 30-80 ℃;
the length of the slit is 1-100 mm;
the width of the slit is 1 mu m-1 mm;
the remixing time is 30-120 min;
the remixing means may include one or more of sanding, high speed shearing, double planetary stirring, ultrasonication, homogenization, and ball milling.
The invention also provides application of the graphene conductive paste in any one of the technical schemes or the graphene conductive paste prepared by the preparation method in any one of the technical schemes in the field of lithium ion batteries.
The invention provides graphene powder which is obtained by spraying and stripping graphite through a supercritical fluid slit. Compared with the prior art, the method provided by the invention aims at the problems that the graphene prepared by the existing physical stripping mode is thick in lamellar layer and not obvious in graphene characteristic, and the energy density of the ternary battery is difficult to optimize under the condition of less addition amount when the graphene is used as the lithium ion battery additive. Graphene prepared by redox has a thin sheet layer but poor conductivity, and the performance of the battery is seriously influenced. The CVD method has the problems of too complicated preparation process, harsh conditions, influence on the production efficiency, difficulty in realizing large-scale industrial production, popularization and application and the like.
The invention is based on the lithium ion battery additive, needs to play a role under the condition of less additive amount, considers that the sheet diameter is large and the thickness is thick, is difficult to optimize the performance of the ternary lithium ion battery under the condition of a small amount, has larger sheet diameter size, enhances the mechanical property of the graphene material, and can reduce the flexibility of a pole piece when being used as the additive of the pole piece of the battery. According to the invention, a mode that supercritical fluid is stripped through slit jet is creatively adopted to obtain nano-grade small-diameter graphene powder, and the size of the graphene sheet diameter is reduced, so that the dispersion degree of graphene is improved when subsequent conductive slurry preparation is facilitated, the effect of increasing the energy density of a battery under the condition of less addition amount can be achieved, the cost can be reduced, and the nano-grade small-diameter graphene powder becomes a good additive for optimizing the performance of a ternary battery.
According to the invention, by adopting a supercritical liquid phase narrow-hole stripping technology, graphene with small thickness and small sheet diameter can be prepared under the conditions of low cost and no pollution, and the graphene can be more favorably and uniformly dispersed in an oil phase or a water phase in the follow-up process to prepare the small-sheet-diameter graphene conductive slurry for the ternary lithium ion battery. The small-diameter graphene conductive paste for the ternary lithium ion battery provided by the invention can realize the nanocrystallization of graphene, improve the electronic conductance as much as possible, reduce the ionic resistance, reduce the consumption of a conductive agent as much as possible, improve the consumption of active substances and increase the energy density of the battery on the premise of ensuring the performance of the battery. And the preparation method has low cost, mild condition, no pollution and easy control, and is more suitable for industrialized popularization and application.
Experimental results show that the small-particle-size graphene conductive agent prepared by the method disclosed by the invention can achieve the effect that the addition of traditional carbon black is 3%, the low addition of the conductive agent provides conditions for the proportion of active substances of a battery, and the energy density of the battery can be improved by 20% under the condition of manufacturing the battery with the same size.
Drawings
Fig. 1 is an SEM scanning electron micrograph of graphene powder prepared in example 1 of the present invention;
fig. 2 is a gold phase diagram of nano graphene conductive paste prepared in example 1 of the present invention;
fig. 3 is an SEM scanning electron micrograph of the graphene powder prepared in example 2 of the present invention;
fig. 4 is a gold phase diagram of nano graphene conductive paste prepared in example 2 of the present invention;
fig. 5 is an SEM scanning electron micrograph of the graphene powder prepared in example 3 of the present invention;
fig. 6 is a gold phase diagram of nano graphene conductive paste prepared in example 3 of the present invention;
FIG. 7 is a SEM Scanning Electron Microscope (SEM) cross-section of the positive electrode plate of NCM811 prepared in example 3 of the invention;
FIG. 8 is a SEM scanning electron micrograph of a cross section of the positive electrode plate of NCM811 prepared in example 3 of the present invention.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
All of the starting materials of the present invention, without particular limitation as to their source, may be purchased commercially or prepared according to conventional methods well known to those skilled in the art.
All raw materials of the invention are not particularly limited in purity, and the invention preferably adopts the purity requirements of analytical purity, graphene preparation or lithium ion battery additive fields.
All the raw materials, the marks and the acronyms thereof belong to the conventional marks and acronyms in the field, each mark and acronym is clear and definite in the field of related application, and the raw materials can be purchased from the market or prepared by a conventional method by the technical staff in the field according to the marks, the acronyms and the corresponding application.
The invention provides graphene powder which is obtained by spraying and stripping graphite through a supercritical fluid slit.
In the invention, in order to further ensure the properties of the graphene powder, the small particle size and the single-layer ratio of the graphene, which are more favorable for subsequent uniform dispersion in the conductive paste and better increase the energy density of the battery, the graphene is preferably small-particle-size graphene, and more preferably nano-scale small-particle-size graphene. Specifically, the sheet diameter of the graphene is preferably not more than 1 μm, more preferably not more than 900nm, more preferably not more than 800nm, more preferably not more than 700nm, specifically, may be 100 to 1000nm, more preferably 300 to 900nm, more preferably 400 to 800 nm. The proportion of the single-layer graphene in the invention can be more than 90%, or more than 85%, or more than 80%, or 80% to 90%, and the balance is less-layer graphene (preferably within 10 layers, more preferably within 8 layers, and more preferably within 5 layers). According to the preparation method provided by the invention, the thickness of the graphene is preferably less than or equal to 10 layers, more preferably less than or equal to 8 layers, and more preferably less than or equal to 5 layers. Graphene thickness the average diameter of 20 plate diameters was chosen at will as measured by atomic force microscopy. Graphene thickness the average diameter of 20 plate diameters was chosen at will as measured by atomic force microscopy.
The specific parameters of the graphene powder are not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product requirements and quality requirements, the properties of the graphene powder, the small particle size and the single-layer ratio of the graphene are further ensured, the graphene is more favorable for being uniformly dispersed in the conductive paste in the follow-up process, and the energy density of the battery is better increased, wherein the particle size of the graphene powder is preferably 0.2-1 μm, more preferably 0.3-0.9 μm, more preferably 0.4-0.8 μm, and more preferably 0.5-0.7 μm.
The specific selection and parameters of the graphite raw material are not particularly limited in principle, and a person skilled in the art can select and adjust the graphite raw material according to actual production conditions, product requirements and quality requirements. The particle size of the graphite is preferably 1-10 μm, more preferably 2-8 μm, and still more preferably 4-6 μm.
In order to further ensure the properties of the graphene powder, the small particle size and the single-layer proportion of the graphene, and be more beneficial to subsequent uniform dispersion in the conductive paste, and better increase the energy density of the battery, the supercritical fluid preferably comprises CO2Supercritical fluid, N2Supercritical fluid, C2H4Supercritical fluid and CCl4One or more of the supercritical fluids, more preferably O2Supercritical fluid, N2Supercritical fluid, C2H4Supercritical fluids or CCl4A supercritical fluid.
In the invention, in order to further ensure the property of the graphene powder, the small particle size and the single-layer ratio of the graphene, which are more favorable for subsequent uniform dispersion in the conductive paste and better increase the energy density of the battery, the length of the slit is preferably 1-100 mm, more preferably 10-80 mm, more preferably 20-70 mm, more preferably 30-60 mm, and more preferably 40-50 mm. The width of the slit is preferably 1-1 mm, more preferably 50-800 μm, more preferably 100-600 μm, more preferably 200-500 μm, more preferably 300-400 μm.
The invention provides graphene conductive slurry which comprises the following raw materials in parts by mass:
2-4 parts by weight of graphene powder according to any one of the above technical schemes;
0.5-1 part by weight of a binder;
95-97.5 parts by weight of a solvent.
The addition amount of the graphene powder is 2-4 parts by weight, preferably 2.2-3.8 parts by weight, more preferably 2.5-3.5 parts by weight, and more preferably 2.7-3.3 parts by weight.
The addition amount of the binder is 0.5-1 part by weight, preferably 0.6-0.9 part by weight, and more preferably 0.7-0.8 part by weight. The specific selection of the binder is not particularly limited in principle, and a person skilled in the art can select and adjust the binder according to actual production conditions, product requirements and quality requirements.
The addition amount of the solvent is 95-97.5 parts by weight, preferably 95.5-97 parts by weight, and more preferably 96-96.5 parts by weight. The specific choice of the solvent is not particularly limited in principle, and can be selected and adjusted by those skilled in the art according to actual production conditions, product requirements and quality requirements, and in order to further ensure the properties of the graphene powder, the small graphene particle size and the monolayer proportion, better facilitate uniform dispersion in the conductive paste and better increase the energy density of the battery, the solvent preferably comprises one or more of NMP, DMF and water, and more preferably NMP, DMF or water.
The invention also provides a preparation method of the graphene powder, which comprises the following steps:
1) under the condition of closed pressure, immersing graphite into supercritical fluid for mixing to obtain supercritical state mixed liquor;
2) pressurizing the supercritical mixed liquid obtained in the above steps, and then carrying out slit jet stripping to obtain graphene powder.
In the present invention, parameters and selections of the raw materials and the products in the preparation method, and corresponding preferred principles, may correspond to parameters and selections of the raw materials and the products in the graphene powder, and corresponding preferred principles, and are not described in detail herein. The specific process and parameter control in the preparation method of the present invention, and the corresponding preferred principle thereof, may correspond to the specific process and parameter control in the following graphene conductive paste, and the corresponding preferred principle thereof, and are not described in detail herein.
The invention also provides a preparation method of the graphene conductive paste, which comprises the following steps:
1) under the condition of closed pressure, immersing graphite into supercritical fluid for mixing to obtain supercritical state mixed liquor;
2) pressurizing the supercritical mixed solution obtained in the step, and then carrying out slit jet stripping to obtain graphene powder;
3) and mixing the graphene powder obtained in the step, the binder and the solvent again to obtain the graphene conductive slurry.
In the present invention, parameters and selections of the raw materials and the products in the preparation method, and corresponding preferred principles, may correspond to parameters and selections of the raw materials and the products in the graphene conductive paste, and corresponding preferred principles, and are not described in detail herein.
The method comprises the steps of firstly, immersing graphite into a supercritical fluid under a closed pressure condition, and mixing to obtain a supercritical state mixed solution.
The specific conditions of the closed pressure are not particularly limited in principle, and a person skilled in the art can select and adjust the conditions according to actual production conditions, product requirements and quality requirements, in order to further ensure the properties of graphene powder, the small particle diameter and the single-layer proportion of graphene, the graphene powder is more favorable for being uniformly dispersed in the conductive slurry, and the energy density of the battery is better increased, the pressure of the closed pressure is preferably greater than or equal to the lowest pressure capable of maintaining the characteristics of the supercritical fluid, specifically 10-75 MPa, also 20-65 MPa, also 30-55 MPa, and also 80-120 MPa.
The method is a complete and refined process, better ensures the properties of the graphene powder, and the small particle size and the single-layer proportion of the graphene, is more favorable for being uniformly dispersed in the conductive paste, and better increases the energy density of the battery, and the graphite preferably comprises the graphite powder subjected to homogenization treatment. The particle size of the graphite is preferably 1-10 μm, more preferably 2-8 μm, and still more preferably 4-6 μm. Wherein, the homogenization treatment mode preferably comprises one or more of sieving, ball milling, airflow crushing and crusher crushing, and more preferably comprises sieving, ball milling, airflow crushing or crusher crushing.
In order to further ensure the properties of graphene powder, the small particle size and the single-layer ratio of graphene, and better facilitate uniform dispersion in conductive paste and better increase the energy density of a battery, the mass ratio of graphite to the supercritical fluid is preferably 1: (100 to 500), more preferably 1: (150 to 450), more preferably 1: (200-400), more preferably 1: (250-350).
The specific immersion mode and parameters are not particularly limited in principle, and those skilled in the art can select and adjust the specific immersion mode and parameters according to actual production conditions, product requirements and quality requirements.
The specific mixing mode and parameters are not particularly limited in principle, and those skilled in the art can select and adjust the mixing mode according to actual production conditions, product requirements and quality requirements, and in order to further ensure the properties of the graphene powder, the small particle size and the single-layer ratio of the graphene, so that the graphene powder is more favorably and uniformly dispersed in the conductive paste and the energy density of the battery is better increased, the mixing mode preferably comprises one or more of double-planetary stirring, high-speed shearing, internal circulation, ultrasound and oscillation, and more preferably comprises planetary stirring, high-speed shearing, internal circulation, ultrasound or oscillation. The mixing time is preferably 30-180 min, more preferably 50-160 min, more preferably 70-140 min, and more preferably 90-120 min. The mixing temperature is preferably 0-100 ℃, more preferably 20-80 ℃, and more preferably 40-60 ℃.
The supercritical mixed solution obtained in the above steps is pressurized and stripped through slit spraying to obtain graphene powder.
The specific parameters of the pressurization are not particularly limited in principle, and a person skilled in the art can select and adjust the specific parameters according to actual production conditions, product requirements and quality requirements, in order to further ensure the properties of the graphene powder, the small particle size and the single-layer ratio of the graphene, the graphene powder is more favorable for being uniformly dispersed in the conductive paste, and the energy density of the battery is better increased, the pressurization pressure is preferably 80-150 MPa, more preferably 90-140 MPa, more preferably 100-130 MPa, and more preferably 110-120 MPa.
The specific parameters of the slit jet are not particularly limited in principle, and a person skilled in the art can select and adjust the specific parameters according to actual production conditions, product requirements and quality requirements, in order to further ensure the properties of graphene powder, the small graphene particle size and the single-layer proportion, the graphene powder is more favorable for being uniformly dispersed in conductive paste, and the energy density of a battery is better increased, the temperature of the slit jet stripping is preferably 30-80 ℃, more preferably 40-70 ℃, and more preferably 50-60 ℃. The length of the slit is preferably 1-100 mm, more preferably 10-80 mm, more preferably 20-70 mm, more preferably 30-60 mm, more preferably 40-50 mm. The width of the slit is preferably 1-1 mm, more preferably 50-800 μm, more preferably 100-600 μm, more preferably 200-500 μm, more preferably 300-400 μm.
Finally, mixing the graphene powder obtained in the step, the binder and the solvent again to obtain the graphene conductive slurry.
The mode and parameters of the remixing are not particularly limited in principle, and those skilled in the art can select and adjust the mode and parameters according to actual production conditions, product requirements and quality requirements, and the mode of the remixing preferably includes one or more of sanding, high-speed shearing, double-planetary stirring, ultrasound, homogenizing and ball milling, more preferably sanding, high-speed shearing, double-planetary stirring, ultrasound, homogenizing or ball milling, in order to further ensure the properties of the graphene powder, the small graphene diameter and the single layer ratio, and further facilitate uniform dispersion in the conductive paste and better increase the energy density of the battery. The time for mixing again is preferably 30-120 min, more preferably 40-110 min, more preferably 50-100 min, more preferably 60-90 min, more preferably 70-80 min.
The invention is a complete and refined integral process, further ensures the properties of graphene powder, small graphene particle size and single-layer proportion, is more favorable for being uniformly dispersed in conductive slurry, and better increases the energy density of a battery, and the preparation process specifically comprises the following steps:
a) homogenizing the particle size of the graphite;
b) soaking the uniform graphite in a supercritical fluid, and stirring;
c) spraying the fully soaked supercritical mixed solution through a ultramicro slit, and then quickly relieving pressure to obtain graphene powder;
d) and uniformly mixing the graphene powder, the binder and the solvent to obtain the conductive paste for the ternary lithium ion battery.
The invention also provides application of the graphene conductive paste in any one of the technical schemes or the graphene conductive paste prepared by the preparation method in any one of the technical schemes in the field of lithium ion batteries.
The specific selection of the lithium ion battery is not particularly limited in principle, and the lithium ion battery known to a person skilled in the art can be selected and adjusted by the person skilled in the art according to actual production conditions, product requirements and quality requirements. The specific application of the invention is more preferably the application on the positive electrode material (such as a pole piece) of the lithium ion battery.
The invention provides small-particle-size graphene powder, small-particle-size graphene conductive paste for a ternary lithium ion battery, and a preparation method and application of the small-particle-size graphene conductive paste. The invention creatively adopts the mode that supercritical fluid is stripped through slit jet, combines specific jet and slit parameters, and particularly adopts the pressurizing mode, thereby greatly reducing the sheet diameter size and the thinness and obtaining nano-grade small-sheet-diameter graphene powder. According to the invention, the intercalation of graphite is realized through the supercritical fluid, and the graphene is prepared by quick pressure relief and stripping through the narrow-hole injection, so that the sheet diameter size of the graphene is reduced, the dispersion degree of the graphene is improved when the conductive slurry is subsequently prepared, the graphene can be directly introduced into an aqueous or oily solution, the uniformly dispersed graphene conductive slurry is obtained through a homogenizing or similar dispersion technology, the effect of increasing the energy density of the battery under the condition of less addition amount can be achieved, the cost can be reduced, and the graphene conductive slurry becomes a good additive for optimizing the performance of the ternary battery.
According to the invention, the graphene with small thickness and small sheet diameter can be prepared under the conditions of low cost and no pollution by using a supercritical liquid phase narrow-hole stripping technology. And uniformly dispersing the graphene in a water phase or an oil phase by adopting a homogeneous emulsification process to prepare the graphene conductive slurry for the ternary cathode material. The small-diameter graphene conductive paste for the ternary lithium ion battery provided by the invention can realize the nanocrystallization of graphene, improve the electronic conductivity as much as possible, reduce the ionic resistance, increase the conductivity of a positive electrode material, improve the compaction density and increase the addition of active substances under the condition of less addition, and reduce the consumption of a conductive agent and improve the consumption of the active substances as much as possible on the premise of ensuring the performance of the battery, thereby increasing the energy density of the ternary battery. And the preparation method has low cost, no pollution and easy control, and is more suitable for industrialized popularization and application.
Experimental results show that the small-particle-size graphene conductive agent prepared by the method disclosed by the invention can achieve the effect that the addition of traditional carbon black is 3%, the low addition of the conductive agent provides conditions for the proportion of active substances of a battery, and the energy density of the battery can be improved by 20% under the condition of manufacturing the battery with the same size.
In order to further illustrate the present invention, a graphene powder, a graphene conductive paste, a preparation method thereof, and an application thereof are described in detail below with reference to examples, but it should be understood that the examples are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, which are only for further illustrating the features and advantages of the present invention, but not for limiting the claims of the present invention, and the scope of the present invention is not limited to the following examples.
Example 1
Pulverizing 10g of graphite powder by a jet mill for 5min for homogenization treatment to obtain graphite powder with the particle size of 2-4 μm, and adding 1L of supercritical CO2Soaking in fluid, stirring at high speed of 800r/min, soaking for 0.5h, pressurizing to 100MPa, peeling off a high-pressure slit, and collecting graphene powder by using filter cloth.
The graphene powder prepared in example 1 of the present invention was characterized.
Referring to fig. 1, fig. 1 is an SEM scanning electron micrograph of the graphene powder prepared in example 1 of the present invention.
As can be seen from FIG. 1, in the graphene powder prepared by the method, the graphene has a small sheet diameter, a size of about 600nm and a thin sheet thickness.
Mixing the graphene powder, PVDF and NMP, and homogenizing and dispersing for 30min by a 70MPa high-pressure homogenizer to obtain the nano graphene conductive slurry with good fluidity for the ternary lithium battery.
The nano graphene conductive paste prepared in embodiment 1 of the present invention is characterized.
Referring to fig. 2, fig. 2 is a gold phase diagram of the nanographene conductive paste prepared in example 1 of the invention.
As can be seen from fig. 2, the small-particle-size graphene in the nano-graphene conductive paste of the present invention is uniformly dispersed without aggregation.
The nano graphene conductive paste prepared in embodiment 1 of the present invention is detected.
The nano graphene conductive paste prepared in the embodiment 1 of the invention is coated on a pole piece to obtain a conductive paste pole piece compounded with the nano graphene conductive paste coating.
The conductive paste pole piece prepared in the embodiment 1 of the invention is detected.
Referring to table 1, table 1 shows the resistivity of the conductive paste electrode sheet prepared according to the example of the present invention.
TABLE 1
The nano graphene conductive paste prepared in the embodiment 1 of the invention is used as a conductive paste to prepare an NCM811 positive pole piece.
The preparation process of the NCM811 positive pole piece comprises the following steps: and uniformly mixing the active substance, the binder, the dispersant and the conductive slurry in a vacuum mixer at a high speed for 60min, coating the uniformly mixed slurry on an aluminum foil, drying in vacuum and then performing roll forming.
The NCM811 pole piece prepared in example 1 of the present invention was tested.
Referring to table 2, table 2 shows the resistivity of the NCM811 pole pieces prepared according to the examples of the present invention.
TABLE 2
Referring to table 3, table 3 is the compacted density of the NCM811 pole pieces prepared according to the examples of the present invention.
TABLE 3
As can be seen from Table 3, the compaction density of the NCM811 pole piece prepared by the invention is 3.5-3.8 g/cm3While the compaction density of the conventional NCM811 pole piece is 3.2g/cm3The following shows that the small-diameter graphene conductive agent prepared by the invention not only can increase the conductivity of the cathode material with a small addition amount,but also the compaction density can be improved.
Compared with the NCM811 pole piece prepared by the common conductive agent, the NCM811 pole piece prepared by the embodiment of the invention is analyzed, and under the condition of the same coating thickness, more NCM811 slurry can be coated on the NCM811 pole piece prepared by the invention.
Referring to table 4, table 4 shows that the mass percentage of the added active material of the NCM811 pole piece prepared by the invention is increased compared with that of the common NCM811 pole piece.
TABLE 4
Example 2
Pulverizing 10g of graphite powder by a jet mill for 5min for homogenization treatment to obtain graphite powder with the particle size of 2-4 μm, and adding 1L of supercritical CO2Soaking in fluid, stirring at high speed of 1000r/min, soaking for 1h, pressurizing to 100MPa, peeling off a slit, and collecting graphene powder with filter cloth.
The graphene powder prepared in embodiment 2 of the present invention is characterized.
Referring to fig. 3, fig. 3 is an SEM scanning electron micrograph of the graphene powder prepared in example 2 of the present invention.
As can be seen from fig. 3, in the graphene powder prepared by the present invention, the graphene has a small sheet diameter, a size of about 500nm, and a thin sheet thickness.
Mixing the graphene powder, PVDF and NMP, and homogenizing and dispersing for 30min by a 70MPa high-pressure homogenizer to obtain the nano graphene conductive slurry with good fluidity for the ternary lithium battery.
The nano graphene conductive paste prepared in embodiment 2 of the present invention is characterized.
Referring to fig. 4, fig. 4 is a gold phase diagram of the nanographene conductive paste prepared in example 2 of the invention.
As can be seen from fig. 4, the small-particle-size graphene in the nano-graphene conductive paste of the present invention is uniformly dispersed without aggregation.
The conductive paste pole piece prepared in embodiment 2 of the invention is detected.
Referring to table 1, table 1 shows the resistivity of the conductive paste electrode sheet prepared according to the example of the present invention.
The nano graphene conductive paste prepared in the embodiment 2 of the invention is used as a conductive paste to prepare an NCM811 positive pole piece.
The preparation process of the NCM811 positive pole piece comprises the following steps: and uniformly mixing the active substance, the binder, the dispersant and the conductive slurry in a vacuum mixer at a high speed for 60min, coating the uniformly mixed slurry on an aluminum foil, drying in vacuum and then performing roll forming.
The NCM811 pole piece prepared in example 2 of the present invention was tested.
Referring to table 2, table 2 shows the resistivity of the NCM811 pole pieces prepared according to the examples of the present invention.
Referring to table 3, table 3 is the compacted density of the NCM811 pole pieces prepared according to the examples of the present invention.
As can be seen from Table 3, the compaction density of the NCM811 pole piece prepared by the invention is 3.5-3.8 g/cm3While the compaction density of the conventional NCM811 pole piece is 3.2g/cm3The following shows that the small-particle-size graphene conductive agent prepared by the invention can not only increase the conductivity of the cathode material but also improve the compaction density with a small addition amount.
Compared with the NCM811 pole piece prepared by the common conductive agent, the NCM811 pole piece prepared by the embodiment of the invention is analyzed, and under the condition of the same coating thickness, more NCM811 slurry can be coated on the NCM811 pole piece prepared by the invention.
Referring to table 4, table 4 shows that the mass percentage of the added active material of the NCM811 pole piece prepared by the invention is increased compared with that of the common NCM811 pole piece.
Example 3
Pulverizing 10g of graphite powder by a jet mill for 5min for homogenization treatment to obtain graphite powder with the particle size of 2-4 μm, and adding 1L of supercritical CO2Soaking in fluid, stirring at high speed of 1500r/min, soaking for 1.5h, pressurizing to 100MPa, peeling off a high-pressure slit, and collecting graphene powder with filter cloth.
The graphene powder prepared in embodiment 3 of the present invention is characterized.
Referring to fig. 5, fig. 5 is an SEM scanning electron micrograph of the graphene powder prepared in example 3 of the present invention.
As can be seen from fig. 5, in the graphene powder prepared by the present invention, the graphene has a small sheet diameter, a size of about 400nm, and a thin sheet thickness.
Mixing the graphene powder, PVDF and NMP, and homogenizing and dispersing for 30min by a 70MPa high-pressure homogenizer to obtain the nano graphene conductive slurry with good fluidity for the ternary lithium battery.
The nano graphene conductive paste prepared in embodiment 3 of the present invention is characterized.
Referring to fig. 6, fig. 6 is a gold phase diagram of the nanographene conductive paste prepared in example 3 of the invention.
As can be seen from fig. 6, the small-particle-size graphene in the nano-graphene conductive paste of the present invention is uniformly dispersed without aggregation.
The conductive paste pole piece prepared in embodiment 3 of the invention is detected.
Referring to table 1, table 1 shows the resistivity of the conductive paste electrode sheet prepared according to the example of the present invention.
The nano graphene conductive paste prepared in the embodiment 3 of the invention is used as a conductive paste to prepare an NCM811 positive pole piece.
The preparation process of the NCM811 positive pole piece comprises the following steps: and uniformly mixing the active substance, the binder, the dispersant and the conductive slurry in a vacuum mixer at a high speed for 60min, coating the uniformly mixed slurry on an aluminum foil, drying in vacuum and then performing roll forming.
The NCM811 pole piece prepared in example 3 of the present invention was tested.
Referring to table 2, table 2 shows the resistivity of the NCM811 pole pieces prepared according to the examples of the present invention.
Referring to table 3, table 3 is the compacted density of the NCM811 pole pieces prepared according to the examples of the present invention.
As can be seen from Table 3, the compaction density of the NCM811 pole piece prepared by the invention is 3.5-3.8 g/cm3While the compaction density of the conventional NCM811 pole piece is 3.2g/cm3Hereinafter, it is shown that the small-particle-size graphene conductive agent prepared by the invention is lessWith the addition amount, the conductivity of the positive electrode material can be increased, and the compaction density can be increased.
Compared with the NCM811 pole piece prepared by the common conductive agent, the NCM811 pole piece prepared by the embodiment of the invention is analyzed, and under the condition of the same coating thickness, more NCM811 slurry can be coated on the NCM811 pole piece prepared by the invention.
Referring to table 4, table 4 shows that the mass percentage of the added active material of the NCM811 pole piece prepared by the invention is increased compared with that of the common NCM811 pole piece.
The NCM811 pole piece prepared in example 3 of the invention was characterized.
Referring to fig. 7, fig. 7 is a SEM scanning electron micrograph of a cross section of the NCM811 positive electrode sheet prepared in example 3 of the present invention.
Referring to fig. 8, fig. 8 is a SEM scanning electron micrograph of a cross section of the NCM811 positive electrode sheet prepared in example 3 of the present invention.
As can be seen from fig. 7 and 8, the longitudinal section of the positive electrode plate is comprehensively observed, the dispersion degree and the extensibility of graphene in the electrode plate are good, no agglomeration phenomenon occurs, the graphene sheet presents a flexible phenomenon, the sheet layer has high softness, and the graphene sheet layer is thin, so that the graphene can be folded and compacted in any shape in the pole plate compacting process, and the compaction density of the NCM811 pole plate can be increased.
The small-particle-size graphene powder and the graphene conductive paste provided by the invention, and the preparation methods and the applications of the small-particle-size graphene powder and the graphene conductive paste. Having described in detail, the principles and embodiments of the present invention have been described herein using specific examples, which are intended to facilitate an understanding of the principles of the invention and their core concepts, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
Claims (10)
1. The graphene powder is characterized by being obtained by carrying out supercritical fluid slit jet stripping on graphite.
2. The graphene powder according to claim 1, wherein the graphene is a small-particle-size graphene;
the thickness of the graphene sheet layer is less than or equal to 10 layers;
the particle size of the graphene powder is 0.2-1 mu m;
the supercritical fluid comprises CO2Supercritical fluid, N2Supercritical fluid, C2H4Supercritical fluid and CCl4One or more of the supercritical fluids.
3. The graphene powder according to claim 1, wherein the sheet diameter of the graphene is 1 μm or less;
the graphite comprises one or more of graphite powder, crystalline flake graphite, artificial graphite, expandable graphite and expanded graphite;
the length of the slit is 1-100 mm;
the width of the slit is 1 mu m-1 mm.
4. The graphene conductive paste is characterized by comprising the following raw materials in percentage by mass:
2-4 parts by weight of the graphene powder according to any one of claims 1-3;
0.5-1 part by weight of a binder;
95-97.5 parts by weight of a solvent.
5. The graphene conductive paste according to claim 4, wherein the binder comprises one or more of polyvinylidene fluoride, styrene butadiene rubber, piperazine, diethanolamine, and polyvinylpyrrolidone;
the solvent comprises one or more of NMP, DMF and water.
6. The preparation method of the graphene conductive paste is characterized by comprising the following steps:
1) under the condition of closed pressure, immersing graphite into supercritical fluid for mixing to obtain supercritical state mixed liquor;
2) pressurizing the supercritical mixed solution obtained in the step, and then carrying out slit jet stripping to obtain graphene powder;
3) and mixing the graphene powder obtained in the step, the binder and the solvent again to obtain the graphene conductive slurry.
7. The method according to claim 6, wherein the graphite comprises a graphite powder after homogenization treatment;
the homogenization treatment mode comprises one or more of sieving, ball milling, airflow crushing and crushing by a crusher;
the particle size of the graphite is 1-10 mu m.
8. The production method according to claim 6, wherein the mass ratio of the graphite to the supercritical fluid is 1: (100-500);
the pressure of the closed belt is 10-75 MPa;
the mixing time is 30-180 min;
the mixing temperature is 0-100 ℃;
the mixing mode comprises one or more of double-planet stirring, high-speed shearing, internal circulation, ultrasonic and vibration.
9. The method according to claim 6, wherein the pressurization pressure is 80 to 150 MPa;
the slit jet stripping temperature is 30-80 ℃;
the length of the slit is 1-100 mm;
the width of the slit is 1 mu m-1 mm;
the remixing time is 30-120 min;
the remixing means may include one or more of sanding, high speed shearing, double planetary stirring, ultrasonication, homogenization, and ball milling.
10. Application of the graphene conductive paste according to any one of claims 4 to 5 or the graphene conductive paste prepared by the preparation method according to any one of claims 6 to 9 in the field of lithium ion batteries.
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Application publication date: 20210618 |