Graphene conductive paste premix, and preparation method and application thereof

Abstract

The application provides a graphene conductive slurry premix, a preparation method and application thereof. The premix comprises graphene and poly(3-thiophene propenoic acid); the preparation method comprises the following steps: mixing graphene, poly(3-thiophene propenoic acid) and a solvent, stirring under low pressure, and then performing high-pressure shearing to obtain the premix. In the application, the graphene conductive slurry premix is modified by poly(3-thiophene propenoic acid), the water solubility of graphene is improved, the viscosity is high, the stability is good, and the conductivity of the conductive slurry is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of graphene conductive materials, and particularly relates to a graphene conductive slurry premix, a preparation method and application thereof. BACKGROUND

[0002] Graphene conductive slurry is commonly used in the preparation of lead-acid batteries. The high specific surface area of graphene can carry more active substances, improve the energy density of the battery, and inhibit the salting of lead sulfate, thereby increasing the cycle performance of the battery. However, graphene is not soluble in water, and the water solubility of graphene needs to be increased through appropriate treatment to increase the stability of the graphene conductive slurry. In actual production, the most direct criterion for the stability of the graphene conductive slurry is the viscosity. In the existing technical production, the viscosity span of the graphene conductive slurry is large, and is often lower than the given minimum standard of 1000 cp. The uniform stability time of the slurry is shortened, and the slurry is prone to sedimentation. Although the conventional thickening agent can increase the viscosity accordingly, the thickening agent is not conductive and can affect the basic performance of the battery.

[0003] In addition, the graphene conductive slurry is a product obtained by mixing graphene, lignin, humic acid, barium sulfate, carbon black and deionized water. The carbon black is attached to the surface of the graphene in the form of small particles to increase the capillary pores of the active substance and improve the utilization rate of the final active substance. The humic acid, as an additive of the negative active substance, can be adsorbed on the surface of the lead crystal of the negative plate to make the lead maintain its high dispersibility, prevent the negative plate from shrinking during the discharge process, and improve the discharge capacity of the battery. Barium sulfate can provide lead sulfate deposition nuclei and reduce the irreversibility of lead sulfate polarization due to its similar structure to lead sulfate. Lignin provides dispersibility and increases the high-rate performance of the battery at low temperature. The existing technology gradually mixes the raw materials through corresponding physical methods to finally form a conductive slurry used as a raw material for subsequent battery processing. However, direct mixing is also not conducive to the increase of the viscosity of the slurry, and the system still has the problem of instability.

[0004] CN103367753A discloses a graphene dispersion liquid modified lead-acid battery negative lead paste, and the weight ratio composition comprises: lead powder 3000 parts, fiber 2-5 parts, graphene water-based dispersion liquid 450-600 parts, acetylene black 10-20 parts, barium sulfate 20-25 parts, sulfuric acid 250-300 parts, and water for controlling the apparent density of the lead paste to 4.0±0.5 g / cm3; the graphene water-based dispersion liquid is obtained by mixing hydrophilic treated graphene and water in a weight ratio of 9-15:1000 and ultrasonic dispersion. However, the stability and uniformity of the graphene dispersion liquid need to be further improved.

[0005] Therefore, developing a kind of graphene conductive slurry with little thickening agent or without thickening agent, which can reach the required viscosity, and has good system stability and conductivity, is a technical problem to be solved in the field. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a graphene conductive slurry premix and its preparation method and application. The graphene conductive slurry premix is modified by poly(3-thiophene acrylic acid) to improve the water solubility of graphene, and has high viscosity, good stability and good conductivity.

[0007] To achieve this purpose, the present application adopts the following technical solutions:

[0008] In the first aspect, the present application provides a graphene conductive slurry premix, which comprises graphene and poly(3-thiophene acrylic acid).

[0009] In the present application, the poly(3-thiophene acrylic acid) main chain is a thiophene structure, which is π-π conjugated with graphene to realize non-covalent bond modification of the graphene surface. The high molecular weight polythiophene acrylic acid is attached to the graphene surface to increase the molecular volume, increase the viscosity of the system, improve the stability of the slurry and extend the storage time of the slurry. At the same time, the poly(3-thiophene acrylic acid) side chain is branched with acrylic acid, which improves the compatibility of the polymer with water, increases the solubility of graphene and slows down the degree of graphene curling. In addition, the fixed structure of the double bond of acrylic acid and the easy combination of carboxylic acid functional groups enable the acrylic acid side chain between long chains to form a network structure, which gives the system certain physical properties and bears the battery reaction space structure. At the same time, the carboxyl group can form hydrogen bonds with the functional groups such as hydroxyl groups left on the surface of graphene, further increasing the stability of the system.

[0010] Preferably, the mass ratio of graphene to poly(3-thiophene acrylic acid) in the premix is (5-20):1, for example, it can be 6:1, 8:1, 10:1, 12:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, etc.

[0011] Preferably, the number average molecular weight of the poly(3-thiophene acrylic acid) is 100-300 g / mol, for example, it can be 120 g / mol, 140 g / mol, 160 g / mol, 180 g / mol, 200 g / mol, 220 g / mol, 240 g / mol, 260 g / mol, 280 g / mol, etc.

[0012] Preferably, the poly(3-thiophene acrylic acid) is prepared by the following method, which comprises:

[0013] The 3-thiophene acrylic acid is reacted with an alcohol compound to obtain 3-thiophene acrylic ester; the 3-thiophene acrylic ester is subjected to a polymerization reaction in the presence of a catalyst to obtain poly(3-thiophene acrylic ester); and the obtained poly(3-thiophene acrylic ester) is subjected to a hydrolysis reaction to obtain the poly(3-thiophene acrylic acid).

[0014] Preferably, the mass ratio of the 3-thiophene acrylic acid to the alcohol compound is 1:(5-10), for example, 1:6, 1:7, 1:8, 1:9, etc.

[0015] In the present application, the alcohol compound includes but is not limited to methanol.

[0016] Preferably, the 3-thiophene acrylic acid is reacted with the alcohol compound in the presence of a protective atmosphere; the protective atmosphere includes but is not limited to nitrogen.

[0017] Preferably, concentrated sulfuric acid is further added before the 3-thiophene acrylic acid is reacted with the alcohol compound.

[0018] Preferably, the reaction time of the 3-thiophene acrylic acid with the alcohol compound is 5-6 h.

[0019] Preferably, the steps of removing the solvent, extraction, and drying are further included after the 3-thiophene acrylic acid is reacted with the alcohol compound.

[0020] In the present application, the intermediate 3-thiophene acrylic ester is prepared first, aiming to protect the functional group carboxyl in the acrylic acid.

[0021] In the present application, the polymerization reaction is carried out in a solvent; the solvent includes but is not limited to chloroform.

[0022] Preferably, the polymerization reaction is carried out in the presence of a protective atmosphere; the protective atmosphere includes but is not limited to nitrogen.

[0023] Preferably, the catalyst includes anhydrous ferric chloride.

[0024] In the present application, the polymerization reaction includes mixing the catalyst and the solvent, stirring for 20-30 min, and then adding a 3-thiophene acrylic ester solution dropwise for reaction; the dropwise adding time is 5-15 min.

[0025] Preferably, the polymerization reaction time is 6-8 h, for example, 6 h, 7 h, 8 h, etc.

[0026] Preferably, the steps of washing and drying are further included after the polymerization reaction.

[0027] Preferably, the hydrolysis reaction includes mixing the poly(3-thiophene acrylic ester) with a sodium hydroxide solution for a hydrolysis reaction.

[0028] In the present application, the concentration of the sodium hydroxide solution is 2 mol / L.

[0029] Preferably, the time of the hydrolysis reaction is 4-8h, for example, 5h, 6h, 7h, etc.; the temperature is 80-120℃, for example, 90℃, 100℃, 110℃, etc.

[0030] In the present application, after the hydrolysis reaction is completed, hydrochloric acid is slowly added until the precipitate appears, and the precipitate is washed and dried to obtain the poly(3-thiophene propenoic acid).

[0031] Preferably, the solid content of the premix is 10-25%, for example, 12%, 14%, 16%, 18%, 20%, 22%, 24%, etc.

[0032] In a second aspect, the present application provides a preparation method of the premix according to the first aspect, the preparation method comprising:

[0033] The graphene, poly(3-thiophene propenoic acid) and solvent are mixed, low-pressure stirring is performed, and then high-pressure shearing is performed to obtain the premix.

[0034] Preferably, the temperature of the mixing is 50-70℃, for example, 52℃, 56℃, 60℃, 62℃, 64℃, 66℃, 68℃, etc.

[0035] Preferably, the pH value of the mixing is 7-8.

[0036] In the present application, appropriate increase in temperature can increase the solubility of the system, graphene is more easily stretched, and the stability of the system is achieved.

[0037] Preferably, the rotation speed of the low-pressure stirring is 500-800rpm, for example, 520rpm, 550rpm, 580rpm, 600rpm, 620rpm, 650rpm, 680rpm, 700rpm, 720rpm, 750rpm, 780rpm, etc.; the pressure is 100-150bar, for example, 105bar, 108bar, 110bar, 112bar, 115bar, 118bar, 120bar, 122bar, 125bar, 128bar, 130bar, 132bar, 135bar, 138bar, 140bar, 142bar, 145bar, 148bar, etc.

[0038] Preferably, the time of the low-pressure stirring is 2-3h.

[0039] Preferably, the high-pressure shearing has a rotation speed of 1500-2000 rpm, for example, 1550 rpm, 1580 rpm, 1600 rpm, 1620 rpm, 1680 rpm, 1700 rpm, 1740 rpm, 1780 rpm, 1800 rpm, 1820 rpm, 1860 rpm, 1900 rpm, 1920 rpm, 1940 rpm, 1980 rpm, etc.; and a pressure of 300-400 bar, for example, 305 bar, 310 bar, 315 bar, 320 bar, 325 bar, 330 bar, 335 bar, 340 bar, 345 bar, 350 bar, 355 bar, 360 bar, 365 bar, 370 bar, 375 bar, 380 bar, 385 bar, 390 bar, 395 bar, etc.

[0040] Preferably, the high-pressure shearing has a time of 1-2 h.

[0041] In the present application, the low-pressure stirring is first used to make the poly(3-thiophene propenoic acid) conjugated adsorption on the surface of graphene; then, the high-speed shearing is used to make the modified graphene fully dissolved in water, further improving the stability of the system.

[0042] Preferably, the preparation method comprises:

[0043] The pH value of the system is maintained at 7-8, and the graphene, poly(3-thiophene propenoic acid) and solvent are mixed at 50-70℃; then, the low-pressure stirring is performed at a rotation speed of 500-800 rpm and a pressure of 100-150 bar for 2-3 h; and then, the high-pressure shearing is performed at a rotation speed of 1500-2000 rpm and a pressure of 300-400 bar for 1-2 h, to obtain the premix.

[0044] In the present application, the pressure greater than 400 bar in the high-pressure shearing does not obviously improve the performance and has high cost.

[0045] In a third aspect, the present application provides a graphene conductive paste, which comprises the premix according to the first aspect, humic acid, carbon black, barium sulfate, lignin and water.

[0046] Preferably, the mass ratio of the premix, humic acid, carbon black, barium sulfate, lignin and water is (10-20):(2-6):(2-6):(8-15):1:(20-40), wherein the specific value in (10-20) can be, for example, 11, 12, 13, 14, 15, 16, 17, 18, 19, etc.; the specific value in (2-6) can be, for example, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, etc.; the specific value in (8-15) can be, for example, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, etc.; and the specific value in (20-40) can be, for example, 22, 24, 26, 28, 30, 32, 34, 36, 38, etc.

[0047] In a fourth aspect, the present application provides a preparation method of the graphene conductive paste according to the third aspect, the preparation method comprising:

[0048] Mixing the premix with humic acid, carbon black, barium sulfate, lignin and water, homogenizing, removing iron, to obtain the graphene conductive paste.

[0049] Preferably, the rotation speed of the mixing is 1000-2000 rpm, for example, 1200 rpm, 1400 rpm, 1600 rpm, 1800 rpm, etc.

[0050] Preferably, the number of homogenization is 2-3 times.

[0051] Preferably, the pressure of the homogenization is 300-400 bar, for example, 320 bar, 340 bar, 360 bar, 380 bar, etc.

[0052] Preferably, the single processing time of the homogenization is 1-1.5 h.

[0053] In the present application, the iron removal is performed by a physical magnetic adsorption iron removal device.

[0054] In the present application, the raw materials such as humic acid contain a large amount of impurity ions, the entry of impurity ions will bring charges to the surface of graphene, affecting the π-π conjugate addition; secondly, humic acid is relatively strong in acidity, the entry of humic acid reduces the pH of the system, which is not conducive to the increase of the viscosity of the system, therefore, the premix is prepared first, which can form a graphene stable system in advance, effectively avoiding these problems.

[0055] The numerical range in the present application not only includes the point values listed above, but also includes any point values between the above numerical ranges that are not listed, and the specific point values included in the range are not listed due to the length and for the sake of simplicity.

[0056] Compared with the prior art, the present application has the following advantages:

[0057] The graphene conductive slurry premix provided by the present application utilizes poly(3-thiophene acrylic acid) to modify graphene through π-π conjugation, realizes non-covalent bond modification of graphene, lets the polymer adhere to the surface of graphene, improves the molecular mass of the whole system, realizes viscosity increase, improves slurry stability, the method is simple and fast, and the non-covalent bond modification does not damage the conductive structure of graphene; meanwhile, by utilizing the solubility of acrylic acid and the existence of carboxyl, the hydrophilic group carboxyl can form hydrogen bonds with water and the surface of graphene, further improving the compatibility of poly(3-thiophene acrylic acid) with graphene and the system; by utilizing the easy combination between functional groups among acrylic acid branched chains, a branched network structure tends to be formed, the final physical properties of the system are improved, the reaction space is built, and finally the conductivity of the slurry is improved. DETAILED DESCRIPTION

[0058] The technical solutions of the present application are further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0059] Preparation Example 1

[0060] Poly(3-thiophene acrylic acid)

[0061] The preparation method comprises the following steps: adding a proper amount of methanol in a flask, adding 3-thiophene acrylic acid (the mass ratio of 3-thiophene acrylic acid to methanol is 1:8) under N2 protection, slowly adding a certain amount of concentrated sulfuric acid (0.8 g), stirring at room temperature for 5 h, rotary evaporation of the solvent, extraction, drying to obtain 3-thiophene acrylic acid methyl ester; dissolving the 3-thiophene acrylic acid methyl ester in chloroform, slowly dropping into a chloroform solution containing anhydrous ferric chloride under N2 protection, the dropping time is 10 min, reacting for 7 h, standing, suction filtration, washing with deionized water for 3 times, drying in a vacuum oven for 6 h to obtain poly(3-thiophene acrylic acid methyl ester); adding the obtained poly(3-thiophene acrylic acid methyl ester) into a sodium hydroxide solution (2 mol / L), hydrolyzing at 100℃ for 6 h, filtering out the insoluble matter, stirring the solution and slowly adding hydrochloric acid until the precipitate appears, finally washing, freeze-drying to obtain poly(3-thiophene acrylic acid).

[0062] Preparation Example 2

[0063] Polythiophene

[0064] The difference from the preparation of poly(3-thiophene acrylic acid methyl ester) is that the monomer is thiophene, and the dosages of other raw materials and the step parameters are the same as those of the method for preparing poly(3-thiophene acrylic acid methyl ester).

[0065] Preparation Example 3

[0066] Conductive resin

[0067] The conductive resin is obtained by mixing acrylic resin and poly-3-thiophene acetic acid (molar ratio 1:1) uniformly, and then adding phosphorus pentoxide into the mixture of acrylic resin and poly-3-thiophene acetic acid, and stirring at 90°C for 18h to carry out anhydride reaction. The amount of phosphorus pentoxide added is 0.5 times the weight of the mixture. The preparation method of the poly-3-thiophene acetic acid is the same as that of poly(3-thiophene acrylic acid), except that the monomer is 3-thiophene acetic acid.

[0068] Preparation Example 4

[0069] Poly-pyrrole acrylic acid

[0070] The difference from the preparation of poly(3-thiophene acrylic acid) is that the monomer is 3-(2-pyrrole) acrylic acid ethyl ester, and the other raw material amounts and step parameters are the same as those in the method for preparing poly(3-thiophene acrylic acid).

[0071] Example 1

[0072] The example provides a graphene conductive slurry premix, which comprises graphene, poly(3-thiophene acrylic acid) and water; the mass ratio of the graphene, poly(3-thiophene acrylic acid) and water is 15:1:50.

[0073] The example provides a preparation method of the graphene conductive slurry premix, which specifically comprises the following steps:

[0074] The graphene, poly(3-thiophene acrylic acid) and water are mixed at 60°C under the condition that the pH value of the system is 7-8, and then stirred at a rotation speed of 600 rpm and a pressure of 100 bar for 3h, and then subjected to high-pressure shearing at a rotation speed of 1500 rpm and a pressure of 400 bar for 1h, so that the graphene conductive slurry premix is obtained.

[0075] Example 2

[0076] The example provides a graphene conductive slurry premix, which comprises graphene, poly(3-thiophene acrylic acid) and water; the mass ratio of the graphene, poly(3-thiophene acrylic acid) and water is 10:1:50.

[0077] The example provides a preparation method of the graphene conductive slurry premix, which specifically comprises the following steps:

[0078] The graphene, poly(3-thiophene acrylic acid) and water are mixed at 50°C under the condition that the pH value of the system is 7-8, and then stirred at a rotation speed of 500 rpm and a pressure of 150 bar for 2h, and then subjected to high-pressure shearing at a rotation speed of 1800 rpm and a pressure of 300 bar for 2h, so that the graphene conductive slurry premix is obtained.

[0079] Example 3

[0080] The embodiment provides a graphene conductive slurry premix, which comprises graphene, poly (3-thiophene acrylic acid) and water; and the mass ratio of the graphene, the poly (3-thiophene acrylic acid) and the water is 18:1:60.

[0081] The embodiment provides a preparation method of the graphene conductive slurry premix, which specifically comprises the following steps:

[0082] The pH value of the system is kept to be 7-8, the graphene, the poly (3-thiophene acrylic acid) and the water are mixed at 70 DEG C, stirring is carried out at a rotating speed of 800 rpm and a pressure of 120 bar for 2.5 h, and high-pressure shearing is carried out at a rotating speed of 1600 rpm and a pressure of 350 bar for 1.5 h, so that the graphene conductive slurry premix is obtained.

[0083] Example 4

[0084] The embodiment provides a graphene conductive slurry premix, which is different from the graphene conductive slurry premix in the embodiment 1 only in that the mass ratio of the graphene and the poly (3-thiophene acrylic acid) is 2:1, and the other components, the dosages and the preparation method are the same as those in the embodiment 1.

[0085] Example 5

[0086] The embodiment provides a graphene conductive slurry premix, which is different from the graphene conductive slurry premix in the embodiment 1 only in that the mass ratio of the graphene and the poly (3-thiophene acrylic acid) is 25:1, and the other components, the dosages and the preparation method are the same as those in the embodiment 1.

[0087] Example 6

[0088] The embodiment provides a graphene conductive slurry premix, which is different from the graphene conductive slurry premix in the embodiment 1 only in that the pressure of low-pressure stirring in the preparation method is 200 bar, and the other components, the dosages and the preparation method are the same as those in the embodiment 1.

[0089] Example 7

[0090] The embodiment provides a graphene conductive slurry premix, which is different from the graphene conductive slurry premix in the embodiment 1 only in that the pressure of high-pressure shearing in the preparation method is 200 bar, and the other components, the dosages and the preparation method are the same as those in the embodiment 1.

[0091] Example 8

[0092] The embodiment provides a graphene conductive slurry premix, which is different from the embodiment 1 only in that, in the preparation method, low-pressure stirring is not performed, and high-pressure shearing is directly performed under the condition of a rotation speed of 1500 rpm and a pressure of 400 bar for 1 h, and other components, the amount of the components and the preparation method are the same as those of the embodiment 1.

[0093] Embodiment 9

[0094] The embodiment provides a graphene conductive slurry premix, which is different from the embodiment 1 only in that, in the preparation method, high-pressure shearing is not performed, and stirring is directly performed under the condition of a rotation speed of 600 rpm and a pressure of 100 bar for 3 h, and other components, the amount of the components and the preparation method are the same as those of the embodiment 1.

[0095] Comparative example 1

[0096] The comparative example provides a graphene conductive slurry premix, which is different from the embodiment 1 only in that, the poly (3-thiophene propenoic acid) is replaced by an equal amount of polythiophene, and other components, the amount of the components and the preparation method are the same as those of the embodiment 1.

[0097] Comparative example 2

[0098] The comparative example provides a graphene conductive slurry premix, which is different from the embodiment 1 only in that, the poly (3-thiophene propenoic acid) is replaced by an equal amount of a mixture of polythiophene (preparation example 2) and acrylic acid (a molar ratio is 1:1), and other components, the amount of the components and the preparation method are the same as those of the embodiment 1.

[0099] Comparative example 3

[0100] The comparative example provides a graphene conductive slurry premix, which is different from the embodiment 1 only in that, the poly (3-thiophene propenoic acid) is replaced by an equal amount of conductive resin (preparation example 3), and other components, the amount of the components and the preparation method are the same as those of the embodiment 1.

[0101] Comparative example 4

[0102] The comparative example provides a graphene conductive slurry premix, which is different from the embodiment 1 only in that, the poly (3-thiophene propenoic acid) is replaced by an equal amount of polypyrrole propenoic acid (preparation example 4), and other components, the amount of the components and the preparation method are the same as those of the embodiment 1.

[0103] Application example 1

[0104] A graphene conductive slurry, which comprises a premix, humic acid, carbon black, barium sulfate, lignin and water in a mass ratio of 16:4:4:12:1:32; the premix comprises the premix provided in the embodiment 1.

[0105] The preparation method of the graphene conductive paste comprises: mixing premix, humic acid, carbon black, barium sulfate, lignin and deionized water under the condition of 1500 rpm, homogenizing treatment, homogenizing frequency is 3 times, homogenizing pressure is 400 bar, homogenizing time is 1.5 h per time, removing iron by physical magnetic adsorption iron remover, and obtaining the conductive paste.

[0106] Application examples 2-9

[0107] The difference between it and application example 1 is only that the premix is provided for application examples 2-9, and the other component amount, ratio and step parameter are the same as application example 1.

[0108] Comparative application examples 1-4

[0109] The difference between it and application example 1 is only that the premix is provided for comparative examples 1-4, and the other component amount, ratio and step parameter are the same as application example 1.

[0110] Comparative application example 5

[0111] A graphene conductive paste, which is different from the application example only in that the preparation method does not prepare the premix in advance, and directly mixes graphene, poly(3-thiophene propylene acid), humic acid, carbon black, barium sulfate, lignin and deionized water, and the other component amount, ratio and step parameter are the same as application example 1.

[0112] Performance test

[0113] (1) Viscosity: Rotational viscometer model: SH52-NDJ-8S

[0114] (2) Stability: 0-5℃ low temperature storage visual observation without sedimentation

[0115] (3) Conductivity: Bench conductivity meter model: DDS-307A

[0116] The specific test results are shown in Table 1:

[0117] Table 1

[0118]

[0119]

[0120] From the above table, the graphene conductive paste premix provided by the application improves the water solubility of graphene by modifying graphene with poly(3-thiophene acrylic acid), and has high viscosity, good stability and good conductivity. As can be seen from application examples 1 to 3, the viscosity of the slurry can be maintained around 1400 mpa.s, the stability time at low temperature can be maintained for more than 6 months, and the initial conductivity of the slurry is also the highest, reaching 36.2-37.1 S / m.

[0121] As can be seen from the comparison of application example 1 and application examples 4 and 5, the mass ratio of graphene to poly(3-thiophene acrylic acid) is not within a specific range. If the proportion of graphene is too high, it will have a greater impact on stability. On the contrary, if the proportion of poly(3-thiophene acrylic acid) is too high, the conductivity of the slurry will drop significantly.

[0122] As can be seen from the comparison of application example 1 and application examples 6-9, not all preparation methods are suitable. In application example 6, the low-pressure pressure is set to 200 bar, which is not conducive to the compounding of poly(3-thiophene acrylic acid) and graphene in the early stage, and has an impact on the performance of the final material. The conductivity and stability are both reduced to a certain extent. In application example 7, the high-pressure shear pressure is too low, which does not mix the final material well, and has a greater impact on the stability and conductivity of the slurry. In application examples 8 and 9, direct high-pressure shearing or direct low-pressure stirring will hinder the formation of a composite structure to some extent, break the compounding trend of graphene and poly(3-thiophene acrylic acid), and greatly reduce the stability and conductivity.

[0123] As can be seen from the comparison of application example 1 and comparative application examples 1-4, other substances are used to replace poly(3-thiophene acrylic acid). In comparative application example 1, polythiophene is directly used, and the solubility of the mixture is not excellent, the stability of the slurry is greatly reduced, and the viscosity is less than 1000 mpa.s. In comparative application example 2, a mixture of polythiophene and acrylic acid is used, and the system is not uniform. The solubilization of acrylic acid is not effectively used, so the stability and conductivity are significantly reduced. In comparative application example 3, conductive resin is directly used, and the compatibility of conductive resin and graphene is poor, and the water solubility is poor, which is not conducive to the final stability of the slurry. In comparative application example 4, polypyrrole acrylic acid is used. The conjugated structure of polypyrrole is not as excellent as that of polythiophene. When graphene has a large surface, the efficiency is not high, so the final stability and conductivity are poor.

[0124] As can be seen from the comparison of application example 1 and comparative application example 5, the conductive slurry obtained by mixing the prepared premix with humic acid and other components has better performance.

[0125] In summary, the graphene conductive paste premix provided by the application utilizes poly(3-thiophene acrylic acid) to modify graphene through pi-pi conjugation; meanwhile, the hydrogen bonds formed between acrylic acid and the surface of graphene improve the viscosity of the system and the solubility of graphene; and due to the existence of double bonds, branched network structures can also be formed, thereby ensuring the construction of reaction space and improving the final physical properties of the system, so that the graphene conductive paste has good stability, high viscosity and good conductivity, the preparation method is simple, the cost is low, and the application range is wide.

[0126] The above specific embodiments further specifically describe the purposes, technical solutions and beneficial effects of the application, and it should be understood that the above description is only for specific embodiments of the application and is not intended to limit the application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the application should be included in the protection scope of the application.

Claims

1. A graphene conductive paste pre-mix, characterized in that, The premix comprises graphene and poly(3-thiophene propenoic acid); The mass ratio of graphene to poly(3-thiophene propenoic acid) in the premix is (5-20):1; The number average molecular weight of the poly(3-thiophene propenoic acid) is 100-300 g / mol; The poly(3-thiophene propenoic acid) is prepared by the following method, which comprises: 3-thiophene propenoic acid is reacted with an alcohol compound to obtain 3-thiophene propenoate; the 3-thiophene propenoate is polymerized in the presence of a catalyst to obtain poly(3-thiophene propenoate); and the obtained poly(3-thiophene propenoate) is hydrolyzed to obtain the poly(3-thiophene propenoic acid); The mass ratio of 3-thiophene propenoic acid to the alcohol compound is 1:(5-10); The reaction time of 3-thiophene propenoic acid with the alcohol compound is 5-6 h; The catalyst comprises anhydrous ferric chloride; The polymerization time is 6-8 h; The solid content of the premix is 10-25%; The preparation method of the premix comprises: mixing graphene, poly(3-thiophene propenoic acid) and a solvent, low-pressure stirring, and then high-pressure shearing to obtain the premix; The pressure of the high-pressure shearing is 300-400 bar.

2. A method of producing a premix according to claim 1, characterized in that, The preparation method comprises: mixing graphene, poly(3-thiophene propenoic acid) and a solvent, low-pressure stirring, and then high-pressure shearing to obtain the premix; The pressure of the high-pressure shearing is 300-400 bar.

3. The production method according to claim 2, characterized by, The temperature of the mixing is 50-70℃.

4. The preparation method according to claim 2, characterized in that, The pH value of the mixing is 7-8.

5. The preparation method according to claim 2, characterized in that, The rotation speed of the low-pressure stirring is 500-800 rpm, and the pressure is 100-150 bar.

6. The preparation method according to claim 2, characterized in that, The time of the low-pressure stirring is 2-3 h.

7. The preparation method according to claim 2, characterized in that, The rotation speed of the high-pressure shearing is 1500-2000 rpm, and the pressure is 300-400 bar.

8. The method of claim 2, wherein, The time of the high-pressure shearing is 1-2 h.

9. The method of claim 2, wherein, The preparation method comprises: mixing graphene, poly(3-thiophene propenoic acid) and a solvent at a pH value of 7-8 and a temperature of 50-70℃, low-pressure stirring at a rotation speed of 500-800 rpm and a pressure of 100-150 bar for 2-3 h, and then high-pressure shearing at a rotation speed of 1500-2000 rpm and a pressure of 300-400 bar for 1-2 h to obtain the premix.

10. A graphene conductive paste, characterized by, The graphene conductive paste comprises the premix of claim 1, humic acid, carbon black, barium sulfate, lignin and water.

11. The graphene conductive paste of claim 10, wherein, The mass ratio of the premix, humic acid, carbon black, barium sulfate, lignin and water is (10-20):(2-6):(2-6):(8-15):1:(20-40).

12. A method of preparing the graphene conductive paste according to claim 10, characterized in that, The preparation method comprises: mixing the premix with humic acid, carbon black, barium sulfate, lignin and water, homogenizing, removing iron, to obtain the graphene conductive paste.

13. The method of claim 12, wherein, The rotation speed of the mixing is 1000-2000 rpm.

14. The method of claim 12, wherein, The number of times of the homogenizing is 2-3.

15. The preparation method according to claim 12, characterized in that, The pressure of the homogenizing is 300-400 bar.

16. The method of claim 12, wherein, The single processing time of the homogenizing is 1-1.5 h.

Images