CN109346240B - Preparation method of graphene conductive slurry - Google Patents
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- CN109346240B CN109346240B CN201811051816.1A CN201811051816A CN109346240B CN 109346240 B CN109346240 B CN 109346240B CN 201811051816 A CN201811051816 A CN 201811051816A CN 109346240 B CN109346240 B CN 109346240B
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Abstract
The invention discloses a preparation method of graphene conductive slurry, which comprises the following steps: 1) putting graphene into NMP, and performing ultrasonic dispersion treatment to obtain a graphene dispersion liquid; 2) putting a carbon material into NMP, and performing ultrasonic dispersion treatment to obtain a carbon material dispersion liquid; 3) mixing the graphene dispersion liquid with the carbon material dispersion liquid, adding superfine carbon powder and superconducting carbon black, and carrying out high-pressure homogenization treatment to obtain a mixed solution; 4) adding PVDF into NMP to prepare a PVDF solution; 5) and adding the PVDF solution into the mixed solution, stirring, and adjusting the viscosity to obtain the graphene conductive slurry. According to the invention, graphene with excellent heat conductivity is used as a raw material, so that the graphene conductive paste is endowed with excellent heat conductivity, and when the battery is charged and discharged at high rate, heat can be rapidly conducted, and the local temperature of the battery is prevented from being overhigh; the graphene conductive slurry can also obviously reduce the internal resistance of the battery and improve the multiplying power performance and the cycle performance of the battery.
Description
Technical Field
The invention relates to the technical field of graphene materials, in particular to a preparation method of graphene slurry with high dispersion performance.
Background
Graphene has excellent optical, electrical and mechanical properties, has important application prospects in the aspects of materials science, micro-nano processing, energy, biomedicine, drug delivery and the like, is considered to be a future revolutionary material, has attracted extensive attention and research of the scientific field by virtue of the special crystal structure performance, is a novel two-dimensional atomic crystal formed by monoatomic layers of sp2 hybridized and connected carbon atoms, has the theoretical thickness of 0.34nm, and is the thinnest two-dimensional material discovered so far. It is widely used in an electrically conductive agent for a lithium battery because of its excellent electrical and thermal conductivity and electron transport channels. However, due to the high specific surface area of graphene, van der waals force exists between graphene material layers, graphene sheet layers are extremely easy to stack and agglomerate, and dispersion in the conductive paste is difficult. The conductivity of the pole piece and the conductivity of the anode and cathode materials in the lithium ion battery are important factors influencing the performance of the battery. The good conductivity can reduce the internal resistance of the battery and improve the cycle performance.
Therefore, the dispersibility of the graphene in the electrode material is improved, and the problems that the slurry is easy to settle and aggregate and the storage is unstable are solved.
Disclosure of Invention
The invention aims to provide a preparation method of graphene conductive slurry with high dispersion performance. The prepared graphene conductive slurry has a good application prospect, for example, the graphene conductive slurry can be coated on the surface of a current collector of a battery in an ultrasonic spraying mode and then dried, and meanwhile, the graphene conductive slurry is added in the pulping process of the positive electrode material, so that the internal resistance of the prepared battery can be reduced, and the rate capability and the cycle performance of the battery can be improved.
In order to achieve the purpose, the invention adopts the following scheme:
a preparation method of graphene conductive paste comprises the following steps:
1) putting graphene prepared by a full-liquid physical stripping method into NMP, and performing ultrasonic dispersion treatment to obtain a graphene dispersion liquid;
2) putting a carbon material into NMP, and performing ultrasonic dispersion treatment to obtain a carbon material dispersion liquid;
3) mixing the graphene dispersion liquid obtained in the step 1) with the carbon material dispersion liquid obtained in the step 2), adding superfine carbon powder and superconducting carbon black, and carrying out high-pressure homogenizing mixing treatment to obtain a mixed solution;
4) adding a certain amount of PVDF into NMP to prepare a PVDF solution;
5) adding the PVDF solution obtained in the step 4) into the mixed solution obtained in the step 3), stirring, and adjusting the viscosity to obtain the graphene conductive slurry.
Preferably, in the step 1), the mass ratio of NMP to graphene is 15-60: 1; the conditions of the ultrasonic dispersion treatment are as follows: the ultrasonic power is 800-. More preferably, the mass ratio of NMP to graphene is 30: 1; the conditions of the ultrasonic dispersion treatment are as follows: the ultrasonic power is 800W, and the ultrasonic time is 60 min.
Preferably, in step 2), the carbon material is selected from one or more of multi-walled carbon nanotubes, carbon black, acetylene black, carbon fibers and conductive graphite.
Preferably, in the step 2), the mass ratio of NMP to the carbon material is 2-20: 1; the conditions of the ultrasonic dispersion treatment are as follows: the ultrasonic power is 800-. More preferably, the mass ratio of NMP to carbon material is 16: 1; the conditions of the ultrasonic dispersion treatment are as follows: the ultrasonic power is 1000W, and the ultrasonic time is 60 min.
Preferably, in the step 3), the pressure of the high-pressure homogenization treatment is 20-30MPa, the time is 2-8 hours, the superfine carbon powder is the special conductive agent carbon powder for the lithium ion battery, the mass ratio of the added special conductive agent carbon powder for the lithium ion battery to the graphene is 1-15:1, and the mass ratio of the added superconducting carbon black to the graphene is 2-12: 1. More preferably, in the step 3), the pressure of the high-pressure homogenization treatment is 20MPa, the time is 4 hours, the mass ratio of the added carbon powder as the special conductive agent for the lithium ion battery to the graphene is 4:1, and the mass ratio of the added superconducting carbon black to the graphene is 10: 1.
The high-pressure homogenization treatment is adopted, the mixture can be uniformly stirred, and substances with larger particle sizes can be cut into substances with smaller particle sizes, so that the filling of gaps of the positive electrode material in the subsequent battery application is facilitated.
Preferably, in the step 4), the mass concentration of the PVDF solution is 1-5%. More preferably, in the step 4), the mass concentration of the PVDF solution is 2.5%.
Preferably, in the step 5), a sand mill is adopted to stir and disperse in a closed manner at the rotation speed of 1000-. More preferably, in step 5), the mixture is dispersed by stirring in a closed environment for 2 hours at a rotation speed of 1500rad/min using a sand mill, and the viscosity is adjusted to 6000 mPas.
Preferably, the preparation method further comprises the steps of packaging the prepared graphene conductive paste and hermetically storing at low temperature after the step 5). The graphene conductive paste is stored in a low-temperature closed manner, so that the stability of the graphene conductive paste is improved.
The invention also provides the graphene conductive paste prepared by the preparation method.
The invention also provides a positive pole piece for the lithium ion battery, which comprises 2-8% of graphene conductive slurry, 88-95% of ternary nickel-cobalt-manganese positive active material and 2-6% of PVDF in percentage by weight. More preferably, the positive electrode plate for the lithium ion battery comprises, by weight, 4% of graphene conductive paste, 92% of ternary nickel-cobalt-manganese positive electrode active material, and 4% of PVDF.
The invention also provides a preparation method of the positive pole piece, which comprises the following steps: stirring the ternary nickel-cobalt-manganese positive electrode active material, PVDF and graphene conductive slurry to prepare electrode slurry, coating the electrode slurry on an aluminum foil, drying and rolling to obtain the positive electrode plate.
More specifically, the preparation method of the graphene conductive paste comprises the following steps:
1) putting graphene into a certain amount of NMP solvent, and performing strong ultrasonic closed dispersion treatment to uniformly disperse the graphene in the NMP (N-methylpyrrolidone) solvent to obtain a graphene dispersion liquid, wherein the mass ratio of the NMP solvent to the graphene is 15-60:1, and the conditions of the ultrasonic dispersion treatment are as follows: the ultrasonic power is 800-;
2) putting a carbon material into a certain amount of NMP solvent, and performing ultrasonic closed dispersion treatment to uniformly disperse the carbon material into the NMP solvent to obtain a carbon material dispersion liquid, wherein the mass ratio of the NMP solvent to the carbon material is 2-20: 1; the conditions of the ultrasonic dispersion treatment are as follows: the ultrasonic power is 800-;
3) mixing the graphene dispersion liquid obtained in the step 1) and the carbon material dispersion liquid obtained in the step 2), putting the mixture into a sealable high-pressure homogenizer, adding sp (superfine carbon powder) and superconducting carbon black with a certain dosage, carrying out hermetic high-pressure homogenization treatment for 2-8 hours under the pressure of 20-30Mpa, and introducing cooling circulating water in the treatment process, wherein the mass ratio of the added superfine carbon powder to the graphene is 1-15:1, and the mass ratio of the added superconducting carbon black to the graphene is 2-12: 1;
4) adding a certain amount of PVDF (polyvinylidene fluoride) into NMP, and hermetically stirring and dispersing to prepare a PVDF solution with the mass concentration of 1-5% for later use;
5) adding the PVDF solution obtained in the step 4) into the mixed solution obtained in the step 3), stirring and dispersing for 2-4 hours in a closed manner by a sand mill at the rotating speed of 1000-;
6) and packaging the prepared graphene conductive slurry, and hermetically storing at low temperature.
Preferably, the graphene adopted by the invention is prepared by a full liquid state physical stripping method.
More specifically, the method for preparing graphene by full liquid aqueous phase physical stripping comprises the following steps:
1) soaking expanded graphite with carbon content of 99.99% and expansion degree of 200 times in ultrapure water, and wetting and soaking for 18-25h, wherein the mass ratio of the volume of the ultrapure water to the mass of the expanded graphite is 8-15ml:1 g;
2) putting the expanded graphite subjected to the wetting and soaking treatment in the step 1) into a sand mill for stirring, and then putting the sand mill for treatment to obtain an expanded graphite soaking solution, wherein the specific operation of the grinding treatment is as follows: putting the expanded graphite subjected to the wetting and soaking treatment into a sand mill filled with a small amount of zirconium beads, stirring for 1.5-4h, setting the rotating speed of the sand mill to be 1000-2000rad/min, and then putting the sand mill into a colloid mill for treatment for 3-6h, wherein the power of the colloid mill is 1-2KW, and the treatment capacity is 18-25L/h;
3) putting the expanded graphite soak solution obtained in the step 2) into a high-pressure homogenizer for high-pressure homogenization treatment, then treating with a high-shear emulsification pump, and then treating with an ultrahigh-pressure critical device to obtain a graphene dispersion solution, wherein the conditions of the high-pressure homogenization treatment are as follows: the time is 1.5-3h, the pressure is 50-100MPa, the time of emulsification treatment is 2.5-5h, and the conditions of ultrahigh pressure critical treatment are as follows: the time is 2.5-5h, and the pressure is 120-;
4) standing and layering the graphene dispersion liquid obtained by the treatment in the step 3), and spray drying at the temperature of 180-250 ℃ to obtain the graphene.
The graphene prepared by adopting a full liquid physical stripping method has a complete lattice structure, contains a small amount of-OH and other hydrophilic groups, has good dispersion performance, and has a specific surface area of 679m2The carbon content of the graphene is 99.99 wt%, the number of layers is 3-10, the content of metal ions is less than or equal to 100ppm, and the thermal conductivity is 3800W/(m.k).
According to the invention, graphene is uniformly dispersed into an NMP solvent in an ultrasonic dispersion mode, and then a carbon material is added for mixing and stirring, so that the operation process is simple. The graphene conductive slurry prepared by the invention can be coated on positive and negative current collectors of a battery by adjusting the concentration and adopting an ultrasonic spraying mode, so that the conductivity of the current collectors is improved, and the coating cost is reduced.
The graphene conductive slurry prepared by the invention is directly mixed with a positive active material, and is uniformly dispersed into a positive material to form a stable and high-speed three-dimensional conductive network system.
The invention has the beneficial effects that:
(1) the ultra-thin graphene which is prepared by adopting a full-liquid physical stripping method and has 6 layers and a thickness of 2nm is used as a raw material, so that the uniform dispersibility and the long-time storage stability of the prepared graphene conductive paste can be improved;
(2) the prepared graphene conductive slurry has good performance, can well play a role by adding a small amount of the graphene conductive slurry, obviously improves the comprehensive performance of the battery, and reduces the manufacturing cost of the battery;
(3) graphene with excellent heat conductivity is used as a raw material, so that the graphene conductive paste is endowed with excellent heat conductivity, and when the battery is charged and discharged at high rate, heat can be rapidly conducted, and the local temperature of the battery is prevented from being overhigh;
(4) the graphene conductive slurry can obviously reduce the internal resistance of the battery, and improve the multiplying power performance and the cycle performance of the battery.
(5) The ultrafine carbon powder and the conductive carbon black have different particle sizes, and are added into the graphene conductive slurry to fill some gaps of the positive electrode material and increase conductive contact points, so that the conductive performance and the heat dissipation performance of the battery are integrally improved.
(6) The graphene raw material adopted by the invention is prepared by a full-liquid physical stripping method, has few lamella, large sheet diameter and 99.99 percent of carbon content, has ultrahigh conductivity, can be used in combination with multi-walled carbon nanotubes and other conductive agents, can reduce the preparation cost, and can be used in the preparation of batteries to improve the performance of the batteries to a greater extent.
Drawings
Fig. 1 is a TEM image of graphene conductive paste prepared in example 1 of the present invention;
fig. 2 is an SEM image of a mixture of the graphene conductive paste prepared in example 1 of the present invention and a ternary NCM cathode material.
Detailed Description
The following examples are presented to assist those skilled in the art in a more complete understanding of the present invention, and are not intended to be limiting. The graphene adopted in the embodiment of the invention is prepared by a full liquid state physical stripping method.
Example 1
A preparation method of graphene conductive paste comprises the following steps:
1) mixing 5g of graphene and 100g of NMP, and performing ultrasonic dispersion treatment for 60min under the ultrasonic power of 1000W to ensure that the graphene is completely dispersed in the NMP to obtain a graphene dispersion liquid;
2) adding 3g of multi-walled carbon nanotubes into 50g of NMP, and performing ultrasonic dispersion treatment for 60min under the ultrasonic power of 1000W to ensure that the multi-walled carbon nanotubes are completely dispersed in the NMP to obtain a carbon material dispersion liquid;
3) mixing the graphene dispersion liquid obtained in the step 1) and the carbon nano tube dispersion liquid obtained in the step 2), putting the mixture into a sealable high-pressure homogenizer, adding 15g of carbon powder serving as a special conductive agent for a lithium ion battery and 10g of superconducting carbon black, homogenizing the mixture under the pressure of 20MPa for 4 hours, and introducing cooling circulating water in the treatment process;
4) adding 5g of PVDF into 195g of NMP, and stirring and dispersing in a closed manner to prepare a PVDF solution with the mass concentration of 2.5% for later use;
5) adding the PVDF solution obtained in the step 4) into the mixed solution obtained in the step 3), stirring and dispersing for 2 hours in a closed manner by adopting a sand mill at the rotating speed of 1500rad/min to ensure that the slurry is uniformly mixed, and simultaneously adjusting the viscosity to 6000mPa & s;
6) and packaging the prepared graphene conductive slurry, and hermetically storing at low temperature.
A preparation method of a positive pole piece comprises the following steps: according to the weight percentage, 92% of ternary nickel-cobalt-manganese positive active material, 4% of PVDF and 4% of graphene conductive slurry are stirred to prepare electrode slurry, the electrode slurry is coated on an aluminum foil, and the electrode slurry is dried and rolled to obtain the positive electrode piece.
Wherein, fig. 1 is a TEM image of the graphene conductive paste prepared in example 1; fig. 2 is an SEM image of a mixture of the graphene conductive paste prepared in example 1 and a ternary NCM cathode material. As shown in fig. 1, the graphene sheet layer and the multi-walled carbon nanotube are in uniform contact to form a closed conductive path, which provides a technical basis for subsequently improving the related conductivity of the lithium ion battery. As can be seen from fig. 2, the graphene conductive paste is uniformly dispersed on the surface of the ternary NCM positive electrode material.
Example 2
A preparation method of graphene conductive paste comprises the following steps:
1) mixing 4g of graphene and 80g of NMP, and performing ultrasonic dispersion treatment for 100min under the ultrasonic power of 1000W to ensure that the graphene is completely dispersed in the NMP to obtain a graphene dispersion liquid;
2) adding 25g of carbon black into 50g of NMP, and performing ultrasonic dispersion treatment for 30min under the ultrasonic power of 800W to ensure that the carbon material is completely dispersed in the NMP to obtain carbon black dispersion liquid;
3) mixing the graphene dispersion liquid obtained in the step 1) and the carbon black dispersion liquid obtained in the step 2), putting the mixture into a sealable high-pressure homogenizer, adding 18g of carbon powder serving as a special conductive agent for a lithium ion battery and 22g of superconducting carbon black, homogenizing the mixture under the pressure of 30MPa for 8 hours, and introducing cooling circulating water in the treatment process;
4) adding 4g of PVDF into 196g of NMP, and stirring and dispersing in a closed manner to prepare a PVDF solution with the mass concentration of 2% for later use;
5) adding the PVDF solution obtained in the step 4) into the mixed solution obtained in the step 3), stirring and dispersing for 4 hours in a closed manner by a sand mill at the rotating speed of 1000rad/min to ensure that the slurry is uniformly mixed, and simultaneously adjusting the viscosity to 6500mPa & s;
6) and packaging the prepared graphene conductive slurry, and hermetically storing at low temperature.
A preparation method of a positive pole piece comprises the following steps: according to the weight percentage, stirring 92% of ternary nickel-cobalt-manganese positive active material, 3% of PVDF and 5% of graphene conductive slurry to prepare electrode slurry, coating the electrode slurry on an aluminum foil, drying and rolling to obtain the positive pole piece.
Example 3
A preparation method of graphene conductive paste comprises the following steps:
1) mixing 3g of graphene and 80g of NMP, and performing ultrasonic dispersion treatment for 60min under the ultrasonic power of 1000W to ensure that the graphene is completely dispersed in the NMP to obtain a graphene dispersion liquid;
2) adding 10g of acetylene black into 50g of NMP, and carrying out ultrasonic dispersion treatment for 30min under the ultrasonic power of 800W to ensure that the carbon material is completely dispersed in the NMP to obtain an acetylene black dispersion liquid;
3) mixing the graphene dispersion liquid obtained in the step 1) and the acetylene black dispersion liquid obtained in the step 2), putting the mixture into a sealable high-pressure homogenizer, adding 20g of carbon powder serving as a special conductive agent for a lithium ion battery and 25g of superconducting carbon black, homogenizing the mixture for 3 hours under the pressure of 30MPa, and introducing cooling circulating water in the treatment process;
4) adding 6g of PVDF into 194g of NMP, and stirring and dispersing in a closed manner to prepare a PVDF solution with the mass concentration of 3% for later use;
5) adding the PVDF solution obtained in the step 4) into the mixed solution obtained in the step 3), stirring and dispersing for 3 hours in a closed manner by adopting a sand mill at the rotating speed of 2000rad/min to ensure that the slurry is uniformly mixed, and simultaneously adjusting the viscosity to 7000mPa & s;
6) and packaging the prepared graphene conductive slurry, and hermetically storing at low temperature.
A preparation method of a positive pole piece comprises the following steps: according to the weight percentage, 90% of ternary nickel-cobalt-manganese positive active material, 3% of PVDF and 7% of graphene conductive slurry are stirred to prepare electrode slurry, the electrode slurry is coated on an aluminum foil, and the electrode slurry is dried and rolled to obtain the positive electrode piece.
Example 4
A preparation method of graphene conductive paste comprises the following steps:
1) mixing 2g of graphene and 100g of NMP, and performing ultrasonic dispersion treatment for 80min under the ultrasonic power of 1000W to ensure that the graphene is completely dispersed in the NMP to obtain a graphene dispersion liquid;
2) adding 10g of carbon fibers into 40g of NMP, and performing ultrasonic dispersion treatment for 40min under the ultrasonic power of 800W to ensure that the carbon materials are completely dispersed in the NMP to obtain carbon fiber dispersion liquid;
3) mixing the graphene dispersion liquid obtained in the step 1) and the carbon fiber dispersion liquid obtained in the step 2), putting the mixture into a sealable high-pressure homogenizer, adding 23g of carbon powder serving as a special conductive agent for a lithium ion battery and 22g of superconducting carbon black, homogenizing the mixture under the pressure of 25MPa for 3 hours, and introducing cooling circulating water in the treatment process;
4) adding 8g of PVDF into 192g of NMP, and stirring and dispersing in a closed manner to prepare a PVDF solution with the mass concentration of 4% for later use;
5) adding the PVDF solution obtained in the step 4) into the mixed solution obtained in the step 3), stirring and dispersing for 3 hours in a closed manner by a sand mill at the rotating speed of 15000rad/min to ensure that the slurry is uniformly mixed, and simultaneously adjusting the viscosity to 6600mPa & s;
6) and packaging the prepared graphene conductive slurry, and hermetically storing at low temperature.
A preparation method of a positive pole piece comprises the following steps: according to the weight percentage, 93 percent of ternary nickel-cobalt-manganese positive active material, 3 percent of PVDF and 4 percent of graphene conductive slurry are stirred to prepare electrode slurry, the electrode slurry is coated on an aluminum foil, and the electrode slurry is dried and rolled to obtain the positive electrode piece.
Example 5
A preparation method of graphene conductive paste comprises the following steps:
1) mixing 8g of graphene and 150g of NMP, and performing ultrasonic dispersion treatment for 100min under the ultrasonic power of 1000W to ensure that the graphene is completely dispersed in the NMP to obtain a graphene dispersion liquid;
2) adding 10g of conductive graphite into 60g of NMP, and performing ultrasonic dispersion treatment for 40min under the ultrasonic power of 800W to ensure that the carbon material is completely dispersed in the NMP to obtain a conductive graphite dispersion liquid;
3) mixing the graphene dispersion liquid obtained in the step 1) and the conductive graphite dispersion liquid obtained in the step 2), putting the mixture into a sealable high-pressure homogenizer, adding 15g of superfine carbon powder and 20g of conductive carbon black, homogenizing under the pressure of 28MPa for 2 hours, and introducing cooling circulating water in the treatment process;
4) adding 10g of PVDF into 190g of NMP, and stirring and dispersing in a closed manner to prepare a PVDF solution with the mass concentration of 5% for later use;
5) adding the PVDF solution obtained in the step 4) into the mixed solution obtained in the step 3), stirring and dispersing for 3 hours in a closed manner by adopting a sand mill at the rotating speed of 2000rad/min to ensure that the slurry is uniformly mixed, and simultaneously adjusting the viscosity to be 7300mPa & s;
6) and packaging the prepared graphene conductive slurry, and hermetically storing at low temperature.
A preparation method of a positive pole piece comprises the following steps: according to the weight percentage, 95% of ternary nickel-cobalt-manganese positive active material, 2% of PVDF and 3% of graphene conductive slurry are stirred to prepare electrode slurry, the electrode slurry is coated on an aluminum foil, and the electrode slurry is dried and rolled to obtain the positive electrode piece.
Comparative example 1
A preparation method of a positive pole piece comprises the following steps: and stirring 92% of ternary NCM active material, 4% of PVDF and 4% of acetylene black to prepare electrode slurry, coating the electrode slurry on an aluminum foil, drying and rolling to obtain the positive electrode plate.
The graphene conductive paste prepared in examples 1 to 5 was subjected to performance testing, and the results are shown in table 1.
Table 1 results of performance test of graphene conductive pastes prepared in examples 1 to 5
The performance of the positive electrode sheets prepared in examples 1 to 5 and the positive electrode sheet prepared in comparative example 1 was tested, and the results are shown in table 2.
The graphene conductive slurry prepared by the invention is used for preparing a ternary nickel-cobalt-aluminum high-rate battery, the battery capacity is 1000mAh, and the battery is tested by adopting a 10C charging mode, a 0.5C discharging mode, a 0.5C charging mode and a 10C discharging mode.
The ternary nickel-cobalt-aluminum high-rate battery is prepared by adding a common conductive agent, the capacity of the battery is 1000mAh, and the test is carried out by adopting a 10C charging mode, a 0.5C discharging mode, a 0.5C charging mode and a 10C discharging mode. The data obtained are shown in Table 2 below
TABLE 2 Properties of the positive electrode sheets prepared in examples 1 to 5 and the positive electrode sheet prepared in comparative example 1
| Performance of | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Comparative example 1 |
| Battery charging rate | 10C | 10C | 10C | 10C | 10C | 10C |
| 10C charging efficiency | 80％ | 85％ | 82％ | 89％ | 86％ | 50％ |
| 10C discharge efficiency | 92％ | 94％ | 93％ | 94％ | 96％ | 63％ |
Claims (8)
1. The preparation method of the graphene conductive paste is characterized by comprising the following steps:
1) putting graphene prepared by a full-liquid physical stripping method into a solvent NMP, and performing ultrasonic dispersion treatment to obtain a graphene dispersion liquid, wherein the specific surface area of the graphene is 679m2The graphene comprises 99.99 wt% of carbon, 6 layers, less than or equal to 100ppm of metal ion, 3800W/(m.k) of heat conductivity coefficient and 2nm of thickness, wherein the graphene contains-OH hydrophilic groups;
2) putting a carbon material into a solvent NMP, and performing ultrasonic dispersion treatment to obtain a carbon material dispersion liquid;
3) mixing the graphene dispersion liquid obtained in the step 1) with the carbon material dispersion liquid obtained in the step 2), adding superfine carbon powder and superconducting carbon black, and carrying out high-pressure homogenization treatment to obtain a mixed liquid;
4) adding a certain amount of PVDF into NMP to prepare a PVDF solution;
5) adding the PVDF solution obtained in the step 4) into the mixed solution obtained in the step 3), stirring, and adjusting the viscosity to obtain graphene conductive slurry; the pressure of high-pressure homogenization treatment is 20-30MPa, the time is 2-8 hours, the superfine carbon powder is the special conductive agent carbon powder for the lithium ion battery, the mass ratio of the special conductive agent carbon powder for the lithium ion battery to the graphene is 1-15:1, and the mass ratio of the added superconducting carbon black to the graphene is 2-12: 1; in the step 4), the mass concentration of the PVDF solution is 1-5%; in the step 5), a sand mill is adopted to stir and disperse for 2 to 4 hours in a closed way at the rotating speed of 1000 plus 2000 rad/min; the viscosity was adjusted to 5500-8000 mPas.
2. The preparation method according to claim 1, wherein in the step 1), the mass ratio of NMP to graphene is 15-60: 1; the conditions of the ultrasonic dispersion treatment are as follows: the ultrasonic power is 800-.
3. The method according to claim 1, wherein in step 2), the carbon material is selected from one or more of multi-walled carbon nanotubes, carbon black, acetylene black, carbon fibers and conductive graphite.
4. The production method according to claim 1, wherein in the step 2), the mass ratio of NMP to the carbon material is 2-20: 1; the conditions of the ultrasonic dispersion treatment are as follows: the ultrasonic power is 800-.
5. The preparation method according to claim 1, further comprising the steps of packaging the prepared graphene conductive paste and storing the graphene conductive paste in a low-temperature sealed manner after the step 5).
6. A graphene conductive paste prepared by the preparation method of any one of claims 1 to 5.
7. A positive electrode plate for a lithium ion battery, which is characterized by comprising, by weight, 2-8% of the graphene conductive paste according to claim 6, 88-95% of a ternary nickel-cobalt-manganese positive electrode active material, and 2-6% of PVDF.
8. The method for preparing the positive pole piece of claim 7, characterized by comprising the following steps: stirring the ternary nickel-cobalt-manganese positive electrode active material, PVDF and graphene conductive slurry to prepare electrode slurry, coating the electrode slurry on an aluminum foil, drying and rolling to obtain the positive electrode plate.
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| CN109903931A (en) * | 2019-02-25 | 2019-06-18 | 天津艾克凯胜石墨烯科技有限公司 | A kind of preparation method of high dispersive graphene composite conductive slurry |
| CN114023968B (en) * | 2019-09-11 | 2023-05-26 | 济南三川新材料科技有限公司 | Conductive paste for battery pole piece, battery pole piece and battery |
| CN110957494A (en) * | 2019-11-08 | 2020-04-03 | 上海超碳石墨烯产业技术有限公司 | Graphene lithium ion battery conductive agent and preparation method thereof |
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