CN113640581B - Graphene conductivity analysis method - Google Patents
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- 229910021389 graphene Inorganic materials 0.000 title claims abstract description 206
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- 238000004458 analytical method Methods 0.000 title claims abstract description 17
- 239000002002 slurry Substances 0.000 claims abstract description 78
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- 238000012360 testing method Methods 0.000 claims abstract description 37
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- 238000000227 grinding Methods 0.000 claims description 25
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 22
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
Abstract
The invention provides a graphene conductivity analysis method, which comprises the following steps: preparing graphene slurry; coating graphene slurry on the surface of a substrate, and drying to form a graphene film; testing film thickness and sheet resistance of a plurality of points on the graphene film; the resistivity of the plurality of points was obtained from the film thicknesses and sheet resistances of the plurality of points, and the average resistivity was used as the resistivity of the graphene powder. According to the method, the conductivity of the graphene in practical application is analyzed, and the graphene with different conductivity is screened based on the conductivity.
Description
Technical Field
The invention relates to the technical field of graphene detection, in particular to a graphene conductivity analysis method.
Background
Currently, there are two main methods for evaluating graphene conductivity:
firstly, directly testing the conductivity of graphene powder, in the patent application of publication No. CN108458906A, testing the conductivity of graphene powder by adopting a tabletting-fixed pressure method, adding a binder into the graphene powder for uniform mixing (the purpose of adding the binder is to facilitate tabletting), fixing the graphene powder mixture under the same pressure for tabletting, taking out the tablet, and then testing the volume conductivity of the tablet by using four probes. The tablet-fixed pressure method is to directly add the binder into the powder, and the biggest disadvantage of the method is that even dispersion of graphene and the binder cannot be ensured, the non-even dispersion of the binder can lead to uneven density of the graphene film under fixed pressure, and the data error obtained by testing is larger and the repeatability is poor.
In another method, as shown in the technical scheme disclosed in the patent application of publication number CN110006956a, graphene powder is dissolved in an organic solvent to prepare a slurry with a certain solid content, then the slurry is changed into an aqueous slurry by a solvent replacement-centrifugation mode, then the graphene powder is obtained by a freeze-drying mode, and then the graphene powder is compressed, and the volume resistivity of the graphene powder under a certain density is tested by a powder resistance meter. The method needs multiple times of centrifugation and freeze drying, and the powder prepared by a single experiment is less, the testing process is complex, the operation is complex and the time cost is high.
In summary, the currently mainstream graphene conductivity test and evaluation methods have certain limitations.
In addition to the above problems, the inventors realized that: whether the graphene can exert excellent conductivity or not, the intrinsic conductivity of the graphene is only one aspect (directly testing the conductivity of the powder), and the dispersibility of the graphene in an application system (forming a graphene conductive network in practical application) plays a main role, so that the conductivity is critical whether the graphene can be applied or not under the premise of ensuring the dispersibility of the graphene.
Disclosure of Invention
Aiming at one or more of the problems in the prior art, the invention provides a graphene conductivity analysis method, which comprises the following steps:
configuring graphene slurry, comprising: adding a dispersing agent into a solvent, stirring and mixing to form a mixed solution; adding graphene powder into the mixed solution, and continuously stirring to obtain graphene pre-dispersion liquid; transferring the graphene pre-dispersion liquid into dispersing equipment, and grinding the graphene pre-dispersion liquid according to a dispersing method of the dispersing equipment to obtain graphene slurry with different graphene particle sizes;
coating graphene slurry on the surface of a substrate, and drying to form a graphene film;
testing film thickness and sheet resistance of a plurality of points on the graphene film;
the resistivity of the plurality of points was obtained from the film thicknesses and sheet resistances of the plurality of points, and the average resistivity was used as the resistivity of the graphene powder.
Optionally, the graphene slurry comprises 1-10wt% of a dispersant, 80-98wt% of a solvent, and 1-10wt% of graphene powder, the dispersant being suitable for the solvent used and dispersing the graphene powder.
Optionally, the step of adding the dispersing agent to the solvent and stirring and mixing to form a mixed solution comprises:
adding 1-10wt% of dispersing agent into 80-98wt% of solvent, stirring and mixing for 0.5-1h to form a mixed solution;
the step of adding the graphene powder into the mixed solution for continuous stirring to obtain the graphene pre-dispersion liquid comprises the following steps of:
adding 1-10wt% of graphene powder into the mixed solution for multiple times, and continuously stirring for 0.5-1h to obtain graphene pre-dispersion liquid.
Optionally, the step of coating the graphene slurry on the surface of the substrate and drying to form the graphene film includes:
dropping ethanol on the glass plate, horizontally placing the PET film on the glass plate, and wiping the PET film to attach the PET film to the glass plate;
coating graphene slurry on a PET film, and scraping the graphene slurry by using a scraper coater;
placing into a blast drying oven, and drying at 70-80deg.C for 1-2 hr.
Optionally, the step of testing the film thickness and the sheet resistance of the plurality of points on the graphene film includes:
and selecting a plurality of points on the graphene film, and testing film thickness and sheet resistance at different points by using a micrometer and a four-probe resistance meter respectively, wherein the plurality of points are preferably arranged in an array.
Optionally, the step of obtaining the resistivity of the plurality of points through the film thickness and the sheet resistance of the plurality of points includes:
film thickness and sheet resistance of the excessive plurality of points obtain resistivity of the plurality of points according to the following
ρ＝R □ *W*F(W/S)/10
R □ Is sheet resistance, unit: Ω/≡;
w is film thickness, unit: mm;
s is the probe spacing, unit: mm;
f (W/S) is a thickness correction coefficient.
Optionally, the step of grinding the graphene pre-dispersion liquid according to the dispersion method of the dispersion device to obtain graphene slurries with different graphene particle sizes includes:
different graphene particle sizes are obtained by controlling the grinding time.
Optionally, the step of configuring the graphene slurry further comprises:
obtaining a fitting curve of the particle size of the graphene and the resistivity of the graphene powder to obtain an optimal particle size, wherein the optimal particle size slurry means that after the particle size of the graphene reaches an optimal value, the particle size is continuously ground to reduce the particle size, and the resistivity change obtained through testing is smaller than a set range.
Optionally, the solvent includes one or more of water, ethanol, NMP, xylene, toluene, and the like organic and inorganic solvents.
Optionally, the step of configuring the graphene slurry further comprises:
and obtaining a fitted curve of the addition ratio of the dispersing agent and the graphene powder and the resistivity of the graphene powder, and obtaining the optimal ratio of the ratio, wherein the optimal ratio is the ratio of the graphene slurry preparation efficiency requirement and the resistivity test error requirement.
Optionally, the adding ratio of the dispersing agent to the graphene powder is 2:1-1:2, and preferably, the adding ratio of the dispersing agent to the graphene powder is 1:1.
Optionally, the step of configuring the graphene slurry further comprises:
obtaining a fitting curve of the adding proportion of the dispersing agent and the graphene powder and the particle size of the graphene;
obtaining a fitting curve of the particle size of the graphene and the resistivity of the graphene powder to obtain an optimal particle size, wherein the optimal particle size slurry means that after the particle size of the graphene reaches an optimal value, the particle size is continuously ground to reduce the particle size, and the resistivity change obtained by testing is smaller than a set range;
and preparing graphene slurry according to the proportion of the dispersant corresponding to the optimal value of the graphene particle size to the addition of the graphene powder.
Optionally, the dispersing device comprises one or more of an oscillator, a sand mill and a ball mill.
Optionally, the step of scraping the graphene slurry with a blade coater includes:
the gap height of the scraper coater is adjusted according to the solid content and the viscosity of the graphene slurry, and the higher the solid content is, the higher the viscosity is, the smaller the gap height is, and the gap height is preferably 100-200 mu m.
The graphene conductivity analysis method is a novel graphene conductivity test method and is used for evaluating the conductivity of graphene in practical application and screening graphenes with different conductivity performances based on the conductivity.
According to the graphene conductivity analysis method, through grinding and dispersing and the addition of the dispersing agent, graphene powder can be uniformly dispersed in a solvent, and the conductivity of the graphene obtained through testing by the method can reflect the conductivity effect exerted by the graphene in practical application.
The graphene conductivity analysis method provided by the invention is simple, convenient, rapid and accurate in evaluating the conductivity of graphene in practical application, small in test error and high in repeatability.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate the invention and together with the embodiments of the invention, serve to explain the invention. In the drawings:
FIG. 1 is a schematic diagram of one embodiment of a graphene conductivity analysis method according to the present invention;
FIG. 2 is a graph of milled particle size of graphene slurry with different dispersant and graphene powder ratios;
FIG. 3 is the conductivity of graphene slurry for different dispersants and graphene powders in example 1;
FIG. 4 is a graph of graphene slurry particle size versus milling time for example 1;
FIG. 5 is a graph of resistivity versus particle size of graphene powder in example 2;
FIG. 6 is a graph of resistivity versus particle size of graphene powder in example 3;
FIG. 7 is a graph showing the relationship between the resistivity of graphene powder and the particle size of graphene slurry in example 4;
fig. 8 is a graph showing the relationship between the resistivity of the graphene powder and the particle size of the graphene slurry in example 5.
Detailed Description
Hereinafter, only certain exemplary embodiments are briefly described. As will be recognized by those of skill in the pertinent art, the described embodiments may be modified in various different ways without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.
The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.
The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.
Fig. 1 is a schematic diagram of an embodiment of a graphene conductivity analysis method according to the present invention, and as shown in fig. 1, the graphene conductivity analysis method includes:
preparation of graphene slurry: firstly, adding 1-10wt% of dispersing agent into 80-98wt% of solvent, stirring and mixing for 0.5-1h to obtain a mixed solution of the dispersing agent and the solvent; adding 1-10wt% of graphene powder into the mixed solution for multiple times, and continuously stirring for 0.5-1h to obtain graphene pre-dispersion liquid; transferring the pre-dispersed slurry to dispersing equipment, and grinding the graphene pre-dispersion liquid according to an equipment dispersing method to obtain slurries with different graphene particle sizes, so as to obtain graphene slurry with the optimal particle size;
coating the PET surface to form a film: after the glass plate is wiped clean by ethanol, the PET film is horizontally placed on the glass plate, so that the PET film is tightly attached to the glass, and the ethanol is used for wiping the PET film to remove surface stains; a sample of graphene slurry of a suitable amount (the greater the solids content, the lesser the amount, preferably 5-10 g) is placed on a PET film, and the slurry is scraped flat with a standard doctor blade coater (slit 100-200 μm);
drying and film forming: putting the mixture into a blast drying box, and drying the mixture for 1 to 2 hours at the temperature of between 70 and 80 ℃;
cutting a square sample with the area of 4cm multiplied by 4cm, taking 9 points (3 multiplied by 3) on the surface of the coating, respectively testing the film thickness and sheet resistance at different points by using a micrometer and a four-probe resistance meter, calculating according to a formula to obtain a resistivity value, and taking the average value to obtain the graphene resistivity.
Example 1
Taking a 2L plastic barrel, adding 1.72kg of deionized water, adding 140g of aqueous dispersant BYK-2013 into the plastic barrel, mechanically stirring for half an hour until the dispersant is completely dissolved in the deionized water, then weighing 140g of graphene powder A (the number of graphene layers is 10-15), adding the graphene powder A into the dispersion liquid for multiple times, and continuing stirring for half an hour after the addition is finished until the powder is completely dispersed in the solution to obtain a pre-dispersion liquid; transferring the pre-dispersion liquid into a small test sand mill for grinding and dispersing, wherein the grinding speed is 2600rpm, the zirconium bead size is 0.1-0.2mm, and the grinding time is 4-6 hours; the same method and process are adopted to prepare slurries with basically consistent particle size but different water-based dispersing agents and graphene powder A mass ratios respectively: 2:1 (slurry 1), 1.5:1 (slurry 2), 1:1 (slurry 3), 0.7:1 (slurry 4), 0.5:1 (slurry 5), test slurry particle size (as shown in fig. 2) and coat film on PET film surface: a few drops of ethanol are dropped on a clean glass plate, the PET film is horizontally placed on the glass plate, and paper is used for wiping the PET film to closely attach the PET film to the glass. Taking a proper amount of slurry sample, placing the slurry sample on a PET film, scraping the slurry by using a standard scraper coater (a gap 200 mu m), placing the slurry in an oven, drying the slurry in the oven at 75 ℃ for one hour, cutting the PET coated with the film into a sample with the size of 4cm multiplied by 4cm, taking 9 points (3 multiplied by 3) on the surface of the sample coating, respectively testing the film thickness and the sheet resistance by using a micrometer and a four-probe resistance meter, calculating according to a formula to obtain a resistivity value, and taking the average value to obtain the graphene resistivity of different slurries, wherein the graphene resistivity of the different slurries is shown in a figure 3, and the conductivity of the coating is improved (the resistivity is reduced) along with the continuous increase of the graphene quantity relative to the addition quantity of a dispersing agent, and the conductivity of the coating is changed greatly along with the increase of the graphene addition quantity under the condition that the dispersing agent/graphene ratio is larger than 1, and the error of 9 test points in the resistivity test is larger; when the dispersant/graphene ratio is less than 1, the resistivity of the coating changes less with the increase of the amount of graphene, and although the error of the test is smaller, the excessive consumption of graphene in the preparation of the slurry causes waste relatively. Comprehensively, when the mass of the dispersant is as follows: when graphene mass=1:1, the slurry preparation efficiency is high, and meanwhile, the coating resistivity test error is small, so that the addition amount ratio of the dispersing agent to the graphene is recommended to be 1.
Example 2
Taking a 2L plastic barrel, adding 1.72kg of deionized water, adding 140g of aqueous dispersant BYK-2013 into the plastic barrel, mechanically stirring for half an hour until the dispersant is completely dissolved in the deionized water, then weighing 140g of graphene powder B (the number of graphene layers is 4-8), adding the graphene powder B into the dispersion liquid for multiple times, and continuing stirring for half an hour after the addition is finished until the powder is completely dispersed in the solution to obtain a pre-dispersion liquid; transferring the pre-dispersion liquid into a small test sand mill for grinding and dispersing, wherein grinding equipment sets parameters: the sanding speed is 2600rpm, the zirconium beads are 0.1-0.2mm in size, the grinding time is 6 hours, samples are reserved every other hour, the slurry particle size of the reserved samples is tested, and a graph of the slurry particle size and the grinding time is shown in FIG. 4;
respectively coating the prepared slurry with different grinding time on the surface of a PET film to form a film: a few drops of ethanol are dropped on a clean glass plate, the PET film is horizontally placed on the glass plate, and paper is used for wiping the PET film to closely attach the PET film to the glass. A proper amount of slurry sample is taken and placed on a PET film, the slurry is scraped by a standard scraper coater (gap 200 mu m), the PET film is placed in an oven for drying at 75 ℃ for one hour, a sample with the size of 4cm multiplied by 4cm is cut out from the PET film coated with the film, 9 points (3 multiplied by 3) are respectively tested on the film thickness and sheet resistance by a micrometer and a four-probe resistance meter on the surface of the sample coating, the resistivity value is calculated according to a formula, and the average value is obtained to obtain the graphene resistivity (the smaller the value is, the better the conductivity is). As shown in fig. 5, as the particle size of graphene decreases, the resistivity of the coating gradually decreases to a certain value, and the resistivity of the graphene powder B in the dispersant system does not change substantially (this value is defined as the resistivity of the graphene powder B). After the particle size d50=1.08 μm of the slurry, the resistivity change of the graphene obtained by testing is tiny, which indicates that the graphene powder B only needs to be ground for 5 hours (or the particle size reaches d50=1.08 μm), the resistivity of the graphene powder B can be obtained by the testing method, and the resistivity of the graphene powder A under the aqueous dispersant BYK-2013 system is as follows: 0.026Ω·cm.
Example 3:
taking a 2L plastic barrel, adding 1.72kg of deionized water, adding 140g of aqueous dispersant BYK-2013 into the plastic barrel, mechanically stirring for half an hour until the dispersant is completely dissolved in the deionized water, then weighing 140g of graphene powder A (the number of graphene layers is 10-15), adding the graphene powder A into the dispersion liquid for multiple times, and continuing stirring for half an hour after the addition is finished until the powder is completely dispersed in the solution to obtain a pre-dispersion liquid; transferring the pre-dispersion liquid into a small test sand mill for grinding and dispersing, wherein the grinding speed is 2600rpm, the zirconium bead size is 0.1-0.2mm, the grinding time is 6 hours, taking a sample every hour to test the size of the slurry, and coating the surface of the PET film to form a film: a few drops of ethanol are dropped on a clean glass plate, the PET film is horizontally placed on the glass plate, and paper is used for wiping the PET film to closely attach the PET film to the glass. A proper amount of slurry sample is taken and placed on a PET film, the slurry is scraped by a standard scraper coater (gap 200 mu m), the PET film is placed in an oven for drying at 75 ℃ for one hour, a sample with the size of 4cm multiplied by 4cm is cut out from the PET film coated with the film, 9 points (3 multiplied by 3) are respectively tested on the film thickness and sheet resistance by a micrometer and a four-probe resistance meter on the surface of the sample coating, the resistivity value is calculated according to a formula, and the average value is obtained to obtain the graphene resistivity (the smaller the value is, the better the conductivity is). As shown in fig. 6, as the particle size of graphene decreases, the resistivity of the coating gradually decreases to a certain value (this value is the resistivity of graphene powder a in the BYK-2013 system of the aqueous dispersant). When the particle size d50=1.18 μm of the slurry, the resistivity of the graphene obtained by the test is basically unchanged, and the resistivity of the graphene powder A can be obtained by the test method, and further, the resistivity of the graphene powder A is 0.04 Ω & cm and is larger than that of the powder B (0.026Ω & cm), which indicates that the graphene powder A does not have the good conductivity of the graphene powder B.
Example 4:
taking a 2L plastic barrel, adding 1.72kg of deionized water, adding 140g of aqueous dispersant BYK-2012 into the plastic barrel, mechanically stirring for half an hour until the dispersant is completely dissolved in the deionized water, then weighing 140g of graphene powder B (the number of graphene layers is 4-8), adding the graphene powder B into the dispersion liquid for multiple times, and continuously stirring for half an hour after the addition is finished until the powder is completely dispersed in the solution to obtain a pre-dispersion liquid; transferring the pre-dispersion liquid into a small test sand mill for grinding and dispersing, wherein the grinding speed is 2600rpm, the zirconium bead size is 0.1-0.2mm, the grinding time is 6 hours, taking a sample every hour to test the size of the slurry, and coating the surface of the PET film to form a film: a few drops of ethanol are dropped on a clean glass plate, the PET film is horizontally placed on the glass plate, and paper is used for wiping the PET film to closely attach the PET film to the glass. A proper amount of slurry sample is taken and placed on a PET film, the slurry is scraped by a standard scraper coater (gap 200 mu m), the PET film is placed in an oven for drying at 75 ℃ for one hour, a sample with the size of 4cm multiplied by 4cm is cut out from the PET film, 9 points (3 multiplied by 3) are respectively measured on the surface of the sample coating by a micrometer and a four-probe resistance meter, the film thickness and the sheet resistance are respectively measured, the resistivity value is calculated according to a formula, and the average value is obtained to obtain the graphene resistivity. As shown in fig. 7, the slurry prepared by using the aqueous dispersant BYK-2012 and the aqueous dispersant BYK-2013 shows the same conductivity rule, and the resistivity of the graphene powder B under the aqueous dispersant BYK-2012 system is as follows: 0.28 Ω·cm.
Example 5:
taking a 2L plastic barrel, adding 1.72kg of deionized water, adding 140g of aqueous dispersant BYK-180 into the plastic barrel, mechanically stirring for half an hour until the dispersant is completely dissolved in the deionized water, then weighing 140g of graphene powder B (the number of graphene layers is 4-8), adding the graphene powder B into the dispersion liquid for multiple times, and continuously stirring for half an hour after the addition is finished until the powder is completely dispersed in the solution to obtain a pre-dispersion liquid; transferring the pre-dispersion liquid into a small test sand mill for grinding and dispersing, wherein the grinding speed is 2600rpm, the zirconium bead size is 0.1-0.2mm, the grinding time is 6 hours, taking a sample every hour to test the size of the slurry, and coating the surface of the PET film to form a film: a few drops of ethanol are dropped on a clean glass plate, the PET film is horizontally placed on the glass plate, and paper is used for wiping the PET film to closely attach the PET film to the glass. A proper amount of slurry sample is taken and placed on a PET film, the slurry is scraped by a standard scraper coater (gap 200 mu m), the PET film is placed in an oven for drying at 75 ℃ for one hour, a sample with the size of 4cm multiplied by 4cm is cut out from the PET film, 9 points (3 multiplied by 3) are respectively measured on the surface of the sample coating by a micrometer and a four-probe resistance meter, the film thickness and the sheet resistance are respectively measured, the resistivity value is calculated according to a formula, and the average value is obtained to obtain the graphene resistivity. As shown in fig. 8, the slurry prepared by using the aqueous dispersant BYK-180, the aqueous dispersant BYK-2013 and the aqueous dispersant BYK-2012 show the same conductivity rule, and the resistivity of the graphene powder B under the aqueous dispersant BYK-180 system is as follows: 0.76 Ω·cm.
According to the graphene conductivity analysis method, the conductivities of graphene under different dispersant systems are different, but the same particle size and resistivity rules are presented, and the method has universality for different aqueous dispersants.
The graphene conductivity analysis method provided by the invention can distinguish the conductivity of different graphene powder, guides the selection of the graphene powder in practical application, is simple, is easy to operate, and is suitable for various solvent systems.
The above embodiments according to the present invention are illustrative, and various changes and modifications may be made by the person skilled in the art without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the contents of the specification, and must be determined according to the scope of the claims.
Claims (12)
1. A graphene conductivity analysis method, comprising:
configuring graphene slurry, comprising: adding a dispersing agent into a solvent, stirring and mixing to form a mixed solution; adding graphene powder into the mixed solution, and continuously stirring to obtain graphene pre-dispersion liquid; wherein, the adding ratio of the dispersing agent to the graphene powder is 1:1; transferring the graphene pre-dispersion liquid into dispersing equipment, and grinding the graphene pre-dispersion liquid according to a dispersing method of the dispersing equipment to obtain graphene slurry with different graphene particle sizes;
coating graphene slurry on the surface of a substrate, and drying to form a graphene film;
testing film thickness and sheet resistance of a plurality of points on the graphene film;
the resistivity of the plurality of points is obtained through the film thickness and the sheet resistance of the plurality of points, the average resistivity is taken as the resistivity of the graphene powder,
the resistivity of the graphene powder with different graphene particle sizes is obtained, and the resistivity of the coating is basically unchanged after gradually decreasing to a certain value along with the continuous decrease of the graphene particle size;
and taking the resistivity as an ordinate and the graphene particle size D50 as an abscissa, obtaining a fitted curve of the graphene particle size and the resistivity of the graphene powder, and obtaining the value of the optimal particle size, wherein the optimal particle size slurry means that after the graphene particle size reaches the optimal value, the particle size is continuously ground to reduce the particle size, and the resistivity change obtained through testing is smaller than a set range.
2. The graphene conductivity analysis method according to claim 1, wherein the graphene slurry contains 1 to 10wt% of a dispersant, 80 to 98wt% of a solvent, and 1 to 10wt% of graphene powder, the dispersant being suitable for the solvent used and dispersing the graphene powder.
3. The graphene conductivity analysis method according to claim 2, wherein the dispersing apparatus comprises one or more of an oscillator, a sand mill, and a ball mill.
4. The method of claim 2, wherein the step of adding the dispersant to the solvent and stirring and mixing the mixture to form a mixed solution comprises:
adding 1-10wt% of dispersing agent into 80-98wt% of solvent, stirring and mixing for 0.5-1h to form a mixed solution;
the step of adding the graphene powder into the mixed solution for continuous stirring to obtain the graphene pre-dispersion liquid comprises the following steps of:
adding 1-10wt% of graphene powder into the mixed solution for multiple times, and continuously stirring for 0.5-1h to obtain graphene pre-dispersion liquid.
5. The method of claim 1, wherein the step of coating the graphene slurry on the surface of the substrate and drying to form the graphene film comprises:
dropping ethanol on the glass plate, horizontally placing the PET film on the glass plate, and wiping the PET film to attach the PET film to the glass plate;
coating graphene slurry on a PET film, and scraping the graphene slurry by using a scraper coater;
placing into a blast drying oven, and drying at 70-80deg.C for 1-2 hr.
6. The method of claim 1, wherein the step of testing film thickness and sheet resistance at a plurality of points on the graphene film comprises:
and selecting a plurality of points on the graphene film, and respectively testing film thickness and sheet resistance at different points by using a micrometer and a four-probe resistance meter.
7. The method of claim 6, wherein the plurality of dots are arranged in an array.
8. The method of claim 1, wherein the step of obtaining the resistivity of the plurality of points from the film thicknesses and the sheet resistances of the plurality of points comprises:
film thickness and sheet resistance of the excessive plurality of points obtain resistivity of the plurality of points according to the following
ρ＝R □ *W*F(W/S)/10
R □ Is sheet resistance, unit: Ω/≡;
w is film thickness, unit: mm;
s is the probe spacing, unit: mm;
f (W/S) is a thickness correction coefficient.
9. The method for analyzing conductivity of graphene according to claim 1, wherein the step of grinding the graphene pre-dispersion liquid according to the dispersion method of the dispersion device to obtain graphene slurries with different graphene particle diameters comprises:
different graphene particle sizes are obtained by controlling the grinding time.
10. The graphene conductivity analysis method according to claim 2, wherein the solvent comprises one or more of water, ethanol, NMP, xylene, toluene organic and inorganic solvents.
11. The method of claim 5, wherein the step of screeding the graphene slurry with a doctor blade applicator comprises:
and adjusting the gap height of the scraper coater according to the solid content and the viscosity of the graphene slurry, wherein the higher the solid content is, the higher the viscosity is, and the smaller the gap height is.
12. The method of claim 11, wherein the gap height is 100-200 μm.
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