Conductive paste and preparation method and application thereof

Abstract

The invention relates to conductive paste and a preparation method and application thereof. The conductive paste comprises the following components in percentage by mass: 89%-92% of metal powder and 1%-5% of a plasticizer, the plasticizer comprises composite conductive fibers and ethyl cellulose; the composite conductive fiber comprises metal ion doped polyaniline and a carbon nanotube, and the metal ion doped polyaniline at least partially coats the carbon nanotube; the mass ratio of the ethyl cellulose to the composite conductive fiber is (2.5-3.5): 1. The conductive paste provided by the invention can realize relatively good rheological property and relatively high conductivity at the same time.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and particularly to a conductive paste, a preparation method thereof, and an application thereof. Background Art

[0002] Under illumination, a solar cell's semiconductor material absorbs photons to generate electron-hole pairs, and these carriers need to be collected to form an electric current. As a conductive structure in direct contact with the active layer of the solar cell, the grid lines can effectively collect these generated carriers. During the preparation process of a solar cell, a conductive paste is usually used for printing the grid lines. However, traditional conductive pastes are difficult to simultaneously achieve good rheology and high conductivity. Summary of the Invention

[0003] Based on this, it is necessary to provide a conductive paste, a preparation method thereof, and an application thereof. The conductive paste of the present application can simultaneously achieve good rheology and high conductivity.

[0004] In a first aspect, the present application provides a conductive paste, comprising the following components in mass percentages: 89% - 92% of metal powder and 1% - 5% of a plasticizer; the plasticizer includes composite conductive fibers and ethyl cellulose; the composite conductive fibers include polyaniline doped with metal ions and carbon nanotubes, and at least part of the polyaniline doped with metal ions coats the carbon nanotubes; the mass ratio of the ethyl cellulose to the composite conductive fibers is (2.5 - 3.5):1.

[0005] In some embodiments, the diameter of the composite conductive fibers is 5μm - 15μm.

[0006] In some embodiments, the aspect ratio of the composite conductive fibers is 3000 - 4000.

[0007] In some embodiments, the metal powder includes silver powder.

[0008] In some embodiments, the metal ions include copper ions.

[0009] In some embodiments, the conductive paste further comprises the following components in mass percentages: 2.2% - 2.5% of glass powder; and / or, 4.2% - 6.1% of a solvent; and / or, 0.05% - 0.1% of a thixotropic agent; and / or, 0.01% - 0.1% of a dispersant; and / or, 0.01% - 0.1% of a surfactant.

[0010] In some embodiments, the solvent includes at least one of diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0011] In some of these embodiments, the thixotropic agent includes at least one of hydrogenated castor oil and its derivatives and polyamide wax.

[0012] In some of these embodiments, the dispersant includes at least one of polyhydroxystearic acid and sodium polycarboxylate.

[0013] In some of these embodiments, the surfactant includes at least one of polyoxyethylene lauryl ether and sodium lauryl polyoxyethylene sulfate.

[0014] In a second aspect, the present application provides a method for preparing a conductive paste, including the following steps:

[0015] Mix raw materials including components with the following mass percentages: 89% - 92% of metal powder and 1% - 5% of plasticizer; the plasticizer includes composite conductive fibers and ethyl cellulose; the composite conductive fibers include metal ion-doped polyaniline and carbon nanotubes, and at least part of the metal ion-doped polyaniline coats the carbon nanotubes; the mass ratio of the ethyl cellulose to the composite conductive fibers is (2.5 - 3.5):1.

[0016] In some of these embodiments, the method for preparing the composite conductive fibers includes the following steps:

[0017] Pretreat the carbon nanotubes with an acid solution;

[0018] Mix the pretreated carbon nanotubes, aniline, and a cationic surfactant in a first solvent to obtain a mixed solution;

[0019] Mix the mixed solution, a metal salt, and an oxidation initiator, and perform a reaction treatment to obtain composite polyaniline particles;

[0020] Mix the composite polyaniline particles with a second solvent to obtain a precursor solution, and perform electrospinning on the precursor to obtain the composite conductive fibers.

[0021] In some of these embodiments, the cationic surfactant includes cetyltrimethylammonium bromide.

[0022] In some of these embodiments, the metal salt includes at least one of soluble copper salts.

[0023] In some of these embodiments, the oxidation initiator includes ammonium persulfate.

[0024] In some of these embodiments, the positive voltage for the electrospinning is 20 kV - 22 kV.

[0025] In some of these embodiments, the negative voltage of the electrospinning is 5 kV to 7 kV.

[0026] In some of these embodiments, the flow rate of the injection pump for the electrospinning is 1 mL / h to 2 mL / h.

[0027] In some of these embodiments, the temperature of the electrospinning is 20 °C to 30 °C.

[0028] In some of these embodiments, the relative humidity of the electrospinning is 55% RH to 65% RH.

[0029] In a third aspect, the present application provides a solar cell, and the grid lines of the solar cell are prepared by using the conductive paste described in any one of the above or the conductive paste prepared by the preparation method of the conductive paste described in any one of the above.

[0030] In the above conductive paste, a plasticizer is jointly constituted by composite conductive fibers and ethyl cellulose. In the conductive paste, the composite conductive fibers and ethyl cellulose can synergistically form a three-dimensional fiber network, serving as the fiber skeleton and carrier of the solid powder in the conductive paste, which can reduce the sedimentation of solid particles during the printing process of the conductive paste, and thus enable the conductive paste to have good rheological properties and conductivity. At the same time, both the carbon nanotubes and the metal ion-doped polyaniline in the composite conductive fibers have good electrical conductivity, which can endow the above three-dimensional fiber network with good electrical conductivity. Further, when the mass ratio of ethyl cellulose to composite conductive fibers in the plasticizer is too high, that is, the composite conductive fibers are too few, the effect of the plasticizer in forming a three-dimensional fiber network is poor, resulting in a poor effect of reducing the sedimentation of solid particles, and further leading to a poor improvement effect on the rheological properties and conductivity of the conductive paste. When the mass ratio of ethyl cellulose to composite conductive fibers in the plasticizer is too low, that is, the ethyl cellulose is too few, it will lead to a poor plasticizing effect of the plasticizer on the conductive paste, and further lead to poor rheological properties of the conductive paste. That is, the conductive paste of the present application can simultaneously achieve good rheological properties and high conductivity. Detailed Embodiments

[0031] To make the above objects, features, and advantages of the present application more apparent and understandable, the following provides a detailed description of the specific embodiments of the present application. Many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0033] In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the embodiments, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to this application.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0035] In this application, unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] An embodiment of this application provides a conductive paste, which includes the following components in mass percentages: 89% - 92% of metal powder and 1% - 5% of plasticizer; the plasticizer includes composite conductive fibers and ethyl cellulose; the composite conductive fibers include metal ion-doped polyaniline and carbon nanotubes, and at least part of the metal ion-doped polyaniline coats the carbon nanotubes; the mass ratio of ethyl cellulose to the composite conductive fibers is (2.5 - 3.5):1.

[0037] In the above conductive paste, a plasticizer is formed by a composite conductive fiber and ethyl cellulose together. In the conductive paste, the composite conductive fiber and ethyl cellulose can synergistically form a three-dimensional fiber network, which serves as the fiber skeleton and carrier for the solid powder in the conductive paste, and can reduce the sedimentation of solid particles during the printing process of the conductive paste, thereby enabling the conductive paste to have good rheological properties and electrical conductivity. At the same time, both the carbon nanotubes and metal ion-doped polyaniline in the composite conductive fiber have good electrical conductivity, which can endow the above three-dimensional fiber network with good electrical conductivity. Further, when the mass ratio of ethyl cellulose to the composite conductive fiber in the plasticizer is too high, that is, the composite conductive fiber is too little, the effect of the plasticizer forming a three-dimensional fiber network is poor, which will lead to a poor effect of reducing the sedimentation of solid particles, and further lead to a poor improvement effect on the rheological properties and electrical conductivity of the conductive paste. When the mass ratio of ethyl cellulose to the composite conductive fiber in the plasticizer is too low, that is, ethyl cellulose is too little, it will lead to a poor plasticizing effect of the plasticizer on the conductive paste, and further lead to poor rheological properties of the conductive paste. That is, the conductive paste of the present application can simultaneously achieve good rheological properties and high electrical conductivity.

[0038] Optionally, the mass ratio of ethyl cellulose to the composite conductive fiber is 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1 or 3.5:1. Alternatively, the mass ratio of ethyl cellulose to the composite conductive fiber can also be within the range between any two of the above mass ratios.

[0039] When the mass percentage of the metal powder is too low, it is likely to result in poor electrical conductivity of the conductive paste. When the mass percentage of the metal powder is too high, the effect of the plasticizer in reducing the sedimentation of solid particles will be poor. Optionally, the mass percentage of the metal powder is 89%, 89.25%, 89.5%, 90%, 90.25%, 90.5%, 90.75%, 91%, 91.25%, 91.5% or 92%. Alternatively, the mass percentage of the metal powder can also be within the range between any two of the above mass percentages.

[0040] When the mass percentage of the plasticizer is too high, it is likely to result in too low viscosity and too large fluidity of the conductive paste, which is likely to lead to uneven film formation and affect the overall performance of the gate line. When the mass percentage of the plasticizer is too low, the effect of reducing the sedimentation of solid particles will be poor. Optionally, the mass percentage of the plasticizer is 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%. Alternatively, the mass percentage of the plasticizer can also be within the range between any two of the above mass percentages.

[0041] In some embodiments, the diameter of the composite conductive fiber is 5 μm to 15 μm.

[0042] Optionally, the diameter of the composite conductive fiber is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm, or the diameter of the composite conductive fiber may also be within the range between any two of the above diameters.

[0043] In some embodiments, the aspect ratio of the composite conductive fiber is 3000 - 4000.

[0044] Optionally, the aspect ratio of the composite conductive fiber is 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900 or 4000, or the aspect ratio of the composite conductive fiber may also be within the range between any two of the above aspect ratios.

[0045] Within the above ranges of the diameter and aspect ratio of the composite conductive fiber, it is beneficial for the composite conductive fiber and ethyl cellulose to synergistically form a three-dimensional fiber network, thereby achieving a better effect of reducing the sedimentation of solid particles during the printing process of the conductive paste.

[0046] In some embodiments, the metal powder includes silver powder.

[0047] In some embodiments, the metal ions include copper ions.

[0048] In some embodiments, the conductive paste further includes glass powder with a mass percentage of 2.2% - 2.5%.

[0049] Within the above range of the mass percentage of the glass powder, the glass powder has a better effect of promoting particle fusion, enhancing the adhesion between the grid line and the substrate material, and reducing the contact resistance between particles. Optionally, the mass percentage of the glass powder is 2.2%, 2.25%, 2.3%, 2.35%, 2.4%, 2.45% or 2.5%, or the mass percentage of the glass powder may also be within the range between any two of the above mass percentages.

[0050] In some embodiments, the conductive paste further includes a solvent with a mass percentage of 4.2% - 6.1%.

[0051] Within the above range of the mass percentage of the solvent, the conductive paste can simultaneously have good ink transfer properties and good adhesion to the substrate. Optionally, the mass percentage of the solvent is 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6% or 6.1%, or the mass percentage of the solvent may also be within the range between any two of the above mass percentages.

[0052] In some of these embodiments, the conductive paste further includes a thixotropic agent in a mass percentage of 0.05% to 0.1%.

[0053] The thixotropic agent can further enhance the effect of the three-dimensional fiber network formed by the composite conductive fibers and ethyl cellulose in reducing the sedimentation of solid particles. Optionally, the mass percentage of the thixotropic agent is 0.05%, 0.06%, 0.07%, 0.08%, 0.09% or 0.1%, or the mass percentage of the thixotropic agent can also be within the range between any two of the above mass percentages.

[0054] In some of these embodiments, the conductive paste further includes a dispersant in a mass percentage of 0.01% to 0.1%. Optionally, the mass percentage of the dispersant is 0.01%, 0.02%, 0.04%, 0.06%, 0.08% or 0.1%, or the mass percentage of the dispersant can also be within the range between any two of the above mass percentages.

[0055] In some of these embodiments, the conductive paste further includes a surfactant in a mass percentage of 0.01% to 0.1%. Optionally, the mass percentage of the surfactant is 0.01%, 0.02%, 0.04%, 0.06%, 0.08% or 0.1%, or the mass percentage of the surfactant can also be within the range between any two of the above mass percentages.

[0056] In some of these embodiments, the solvent includes diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0057] In some of these embodiments, the thixotropic agent includes at least one of hydrogenated castor oil and its derivatives and polyamide wax.

[0058] In some of these embodiments, the dispersant includes at least one of polyhydroxystearic acid and sodium polycarboxylate.

[0059] In some of these embodiments, the surfactant includes at least one of lauryl alcohol polyoxyethylene ether and sodium fatty alcohol polyoxyethylene ether sulfate.

[0060] Another embodiment of the present application provides a method for preparing a conductive paste, including the following steps:

[0061] Mix raw materials including the following components in mass percentages: 89% to 92% of metal powder and 1% to 5% of a plasticizer; the plasticizer includes composite conductive fibers and ethyl cellulose; the composite conductive fibers include metal ion-doped polyaniline and carbon nanotubes, and at least part of the metal ion-doped polyaniline coats the carbon nanotubes; the mass ratio of ethyl cellulose to the composite conductive fibers is (2.5 to 3.5):1.

[0062] In some of these embodiments, the method for preparing the composite conductive fiber comprises the following steps:

[0063] Pre-treat the carbon nanotubes with an acid solution;

[0064] Mix the pre-treated carbon nanotubes, aniline, and a cationic surfactant in a first solvent to obtain a mixed solution;

[0065] Mix the mixed solution, a metal salt, and an oxidation initiator, and perform a reaction treatment to obtain composite polyaniline particles;

[0066] Mix the composite polyaniline particles with a second solvent to obtain a precursor solution, and electrospin the precursor to obtain a composite conductive fiber.

[0067] In some of these embodiments, the cationic surfactant includes cetyltrimethylammonium bromide.

[0068] In some of these embodiments, the metal salt includes at least one of soluble copper salts.

[0069] In some of these embodiments, the metal salt includes copper sulfate pentahydrate.

[0070] In some of these embodiments, the oxidation initiator includes ammonium persulfate.

[0071] In some of these embodiments, the first solvent includes distilled water.

[0072] In some of these embodiments, the second solvent includes at least one of polymethyl methacrylate (PMMA) and N-methyl-2-pyrrolidone (NMP).

[0073] In some of these embodiments, mixing the mixed solution, the metal salt, and the oxidation initiator, and performing the reaction treatment includes the following steps:

[0074] Add the metal salt to the mixed solution under stirring, continuously stir and continue to dropwise add the oxidizing agent to obtain a reaction product;

[0075] Perform solid-liquid separation, washing, and drying on the reaction product to obtain composite polyaniline particles.

[0076] In some of these embodiments, the method for preparing the conductive paste comprises the following steps:

[0077] Mix the composite conductive fiber and ethyl cellulose in a preset ratio to obtain a plasticizer;

[0078] Mix the plasticizer with other components of the conductive paste in a preset ratio and disperse them to obtain the conductive paste.

[0079] In some of these embodiments, the positive voltage of the electrospinning is 20 kV to 22 kV.

[0080] Optionally, the positive voltage of the electrospinning is 20 kV, 20.5 kV, 21 kV, 21.5 kV or 22 kV, or the positive voltage of the electrospinning can also be within the range between any two of the above positive voltages.

[0081] In some of these embodiments, the negative voltage of the electrospinning is 5 kV to 7 kV.

[0082] Optionally, the negative voltage of the electrospinning is 5 kV, 5.5 kV, 6 kV, 6.5 kV or 7 kV, or the negative voltage of the electrospinning can also be within the range between any two of the above negative voltages.

[0083] In some of these embodiments, the flow rate of the injection pump for the electrospinning is 1 mL / h to 2 mL / h.

[0084] Optionally, the flow rate of the injection pump for the electrospinning is 1 mL / h, 1.2 mL / h, 1.4 mL / h, 1.6 mL / h, 1.8 mL / h or 2 mL / h, or the flow rate of the injection pump for the electrospinning can also be within the range between any two of the above flow rates.

[0085] In some of these embodiments, the temperature of the electrospinning is 20 °C to 30 °C.

[0086] Optionally, the temperature of the electrospinning is 20 °C, 22 °C, 24 °C, 26 °C, 28 °C or 30 °C, or the temperature of the electrospinning can also be within the range between any two of the above temperatures.

[0087] In some of these embodiments, the relative humidity of the electrospinning is 55%RH to 65%RH.

[0088] Optionally, the relative humidity of the electrospinning is 55%RH, 56%RH, 57%RH, 58%RH, 59%RH, 60%RH, 61%RH, 62%RH, 63%RH, 64%RH or 65%RH, or the relative humidity of the electrospinning can also be within the range between any two of the above relative humidities.

[0089] Within the ranges of the above electrospinning processes, it is convenient to prepare composite conductive fibers with appropriate fiber lengths and aspect ratios by electrospinning, and at the same time, it can make the polyaniline doped with metal ions in the composite conductive fibers have a good coating effect on the carbon nanotubes.

[0090] Another embodiment of the present application provides a solar cell, and the grid lines of the solar cell are prepared by using the conductive paste of any one of the above or the conductive paste prepared by the preparation method of any one of the above conductive pastes.

[0091] The following are specific examples

[0092] Example 1

[0093] The components and mass percentages of the conductive paste in Example 1 are as follows:

[0094] 91.5% silver powder, 2.3% glass powder, 5% solvent, 1.1% plasticizer, 0.05% dispersant, and 0.05% surfactant. Among them, the mass ratio of ethyl cellulose to composite conductive fiber is 3:1. In the solvent, the mass ratio of diethylene glycol monobutyl ether is 1.8%, the mass ratio of diethylene glycol dibutyl ether is 1.5%, and the mass ratio of alcohol ester 12 is 1.7%. The dispersant is polyhydroxystearic acid. The surfactant is lauryl alcohol polyoxyethylene ether.

[0095] Preparation method of the conductive paste:

[0096] (1) Aniline is subjected to secondary distillation under vacuum conditions to remove oxidation impurities. Carbon nanotubes are pretreated in an acid solution, refluxed and stirred at 75 °C for 1 h, and the pretreated carbon nanotubes are obtained after filtration, washing, and drying.

[0097] (2) The pretreated carbon nanotubes are dispersed in distilled water by ultrasonic waves. In the dispersed carbon nanotube mixture, cetyltrimethylammonium bromide (CTAB) and aniline are added. Copper sulfate (CuSO 4 ·5H 2 O is added to the above reaction mixture, stirred for 15 minutes, and then ammonium persulfate (APS) is added dropwise. The reaction mixture is stirred, and the obtained product is filtered, washed, and dried in an oven at 60 °C to obtain composite polyaniline particles.

[0098] (3) The composite polyaniline particles are added to a mixed solution of PMMA and NMP as a precursor, and electrospinning is used to prepare composite conductive fibers with the precursor. The electrospinning process parameters are: positive voltage 21 kv, negative voltage 6 kv, receiving distance 19 cm, injection pump flow rate 1.5 mL / h, temperature 25 °C, relative humidity 55%RH - 65%RH.

[0099] (4) Ethyl cellulose and the prepared composite conductive fiber are mixed into a plasticizer according to a preset mass percentage. The plasticizer component and other components are stirred and dispersed on a dispersion device at a speed of 500 rpm / min for 5 min, and then stirred and dispersed at a speed of 1500 rpm / min for 1.5 h until the dispersion is complete to obtain the conductive paste.

[0100] Example 2

[0101] The conductive paste in Example 2 is basically the same as that in Example 1, and the only difference is that the mass ratio of ethyl cellulose to composite conductive fibers is 2.5:1.

[0102] Example 3

[0103] The conductive paste in Example 3 is basically the same as that in Example 1, and the only difference is that the mass ratio of ethyl cellulose to composite conductive fibers is 3.5:1.

[0104] Comparative Example 1

[0105] The conductive paste in Comparative Example 1 is basically the same as that in Example 1, and the only difference is that it does not contain composite conductive fibers.

[0106] Comparative Example 2

[0107] The conductive paste in Comparative Example 2 is basically the same as that in Example 1, and the only difference is that it does not contain ethyl cellulose.

[0108] Comparative Example 3

[0109] The conductive paste in Comparative Example 3 is basically the same as that in Example 1, and the only difference is that the mass ratio of ethyl cellulose to composite conductive fibers is 2:1.

[0110] Comparative Example 4

[0111] The conductive paste in Comparative Example 4 is basically the same as that in Example 1, and the only difference is that the mass ratio of ethyl cellulose to composite conductive fibers is 4:1.

[0112] The conductive pastes in Examples 1 to 3 and Comparative Examples 1 to 4 are used to print the electrodes of solar cells. Before printing, weigh the weight of the cell, denoted as m1; print the conductive paste onto the surface of the cell by screen printing, and immediately weigh the weight of the cell after printing, denoted as m2. m1 - m2 is the wet weight of the conductive paste; then sinter the cell at high temperature to make the solar cell electrode, and then conduct I-V tests on each cell one by one. The test results are shown in Table 1 below:

[0113] Table 1

[0114]

[0115] By comparing the test data of each example and comparative example, it can be seen that in the conductive paste of the present application, when the mass ratio of ethyl cellulose to composite conductive fiber is (2.5-3.5):1, the sedimentation of solid particles during the printing process of the conductive paste can be reduced, thereby enabling the conductive paste to have good rheological properties and conductivity, and thus enabling the prepared solar cell to have good photoelectric conversion efficiency. By comparing the test data of each example, it can be seen that when the mass ratio of ethyl cellulose to composite conductive fiber is 3:1, the solar cell prepared from the conductive paste has better photoelectric conversion performance than other examples.

[0116] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0117] The above-described embodiments only represent several implementation manners of the present application, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims, and the description and embodiments can be used to explain the content of the claims.

Claims

1. A conductive paste, characterized in that: The invention comprises the following components in mass percentage: 89% to 92% of metal powder and 1% to 5% of plasticizer; the plasticizer comprises composite conductive fibers and ethyl cellulose; the composite conductive fibers comprise polyaniline doped with metal ions and carbon nanotubes, and the metal ion-doped polyaniline at least partially coats the carbon nanotubes; the mass ratio of the ethyl cellulose to the composite conductive fibers is (2.5 to 3.5):

1.

2. The conductive paste according to claim 1, characterized in that: The diameter of the composite conductive fiber is 5 μm to 15 μm; and / or, The aspect ratio of the composite conductive fiber is 3000-4000.

3. The conductive paste according to claim 1, characterized in that: The metal powder comprises silver powder; and / or, The metal ions include copper ions.

4. The conductive paste according to any one of claims 1 to 3, characterized in that: The conductive paste also includes the following components in percentage by mass: 2.2% to 2.5% of glass powder; and / or 4.2% to 6.1% of solvent; and / or 0.05% to 0.1% of thixotropic agent; and / or 0.01% to 0.1% of dispersant; and / or 0.01% to 0.1% of surfactant.

5. The conductive paste according to claim 4, characterized in that: The solvent includes at least one of diethylene glycol monobutyl ether, diethylene glycol dibutyl ether and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate; and / or, The thixotropic agent comprises at least one of hydrogenated castor oil and its derivatives and polyamide wax; and / or, The dispersant comprises at least one of polyhydroxystearic acid and sodium polycarboxylate; and / or, The surfactant includes at least one of lauryl alcohol polyoxyethylene ether and fatty alcohol polyoxyethylene ether sodium sulfate.

6. A method for preparing a conductive paste, characterized in that: The steps include: The raw materials including the following components in mass percentage are mixed: 89% to 92% of metal powder and 1% to 5% of plasticizer; the plasticizer includes composite conductive fibers and ethyl cellulose; the composite conductive fibers include metal ion-doped polyaniline and carbon nanotubes, and the metal ion-doped polyaniline at least partially coats the carbon nanotubes; the mass ratio of the ethyl cellulose to the composite conductive fibers is (2.5 to 3.5):

1.

7. The method for preparing the conductive paste according to claim 6, characterized in that: The preparation method of the composite conductive fiber comprises the following steps: Pre-treating the carbon nanotubes using an acid solution; Mixing the pretreated carbon nanotubes, aniline and a cationic surfactant in a first solvent to obtain a mixed solution; The mixed solution, the metal salt and the oxidation initiator are mixed and subjected to reaction treatment to obtain composite polyaniline particles; The composite polyaniline particles are mixed with a second solvent to obtain a precursor solution, and the precursor is subjected to electrostatic spinning to obtain the composite conductive fiber.

8. The method for preparing the conductive paste according to claim 7, characterized in that: The cationic surfactant comprises cetyltrimethylammonium bromide; and / or, The metal salt comprises at least one of a soluble copper salt; and / or, The oxidation initiator includes ammonium persulfate.

9. The method for preparing the conductive paste according to claim 7, characterized in that: The positive voltage of the electrospinning is 20 kV to 22 kV; and / or, The negative voltage of the electrospinning is 5 kV to 7 kV; and / or, The flow rate of the electrospinning syringe pump is 1 mL / h to 2 mL / h; and / or, The electrospinning temperature is 20°C to 30°C; and / or, The relative humidity of the electrospinning is 55%RH~65%RH.

10. A solar cell, characterized in that: The grid lines of the solar cell are prepared by the conductive paste described in any one of claims 1 to 5 or the conductive paste prepared by the preparation method of the conductive paste described in any one of claims 6 to 9.

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