A high-welding-tensile low-temperature silver paste for solar cells and its preparation method

Abstract

The present invention relates to a low-temperature silver paste for high-welding-tensile solar cells and a preparation method thereof. The low-temperature silver paste for high-welding-tensile solar cells comprises components in the following mass percentages: 75%-90% silver powder, 1%-5% nano-bismuth powder, 3%-8% resin, 3%-8% organic solvent, 0.1%-1% curing agent, 0.2%-1% dispersant, and 0.5%-2% adhesion promoter. By adding a certain amount of nano-bismuth powder to the low-temperature silver paste, the present invention changes the performance of the silver paste. The molten nano-bismuth powder has excellent adhesiveness to both the substrate and silver, and the welding tensile force of the silver paste can be greatly improved. Thus, the present invention innovatively develops a low-temperature conductive silver paste for high-welding-tensile solar cells. Experimental tests prove that the welding tensile force of the low-temperature silver paste provided by the present invention reaches a leading level, has a wider applicability to the welding of HJT cell wafers, and improves the service life of HJT cell modules.

Description

Technical Field

[0001] The present invention belongs to the technical field of conductive silver pastes, and particularly relates to a low-temperature silver paste for solar cells with high welding tensile strength and a preparation method thereof. Background Art

[0002] Energy is the foundation of the world's economic and social development. With the consumption of traditional fossil energy and the deterioration of the human living environment, the development of clean and renewable energy has attracted the high attention of governments around the world. China ranks first in the world in terms of photovoltaic production and installed capacity, but still cannot meet the demand. At present, the mass production efficiency of mainstream PERC cells reaches 23%, approaching the theoretical limit of 24%, while HJT cells are favored for their higher efficiency (26.5%), simpler process flow, low attenuation, and low temperature coefficient.

[0003] As an important part of heterojunction cell photovoltaic power generation, HJT silver paste has been monopolized by foreign countries in the market for a long time due to its high technical barriers. The main problems in the development of domestic HJT silver paste are low welding tensile strength and high resistivity. Among them, the problem of welding tensile strength will seriously affect the welding of photovoltaic modules. Therefore, it is necessary to develop an HJT low-temperature curing solar cell silver paste with high welding tensile strength. Summary of the Invention

[0004] The present invention aims to solve the problems that the low-temperature silver paste used in conventional HJT cells is not easy to weld and has a small welding tensile strength, and develops a low-temperature silver paste for solar cells with high welding tensile strength. The specific scheme is as follows:

[0005] A low-temperature silver paste for solar cells with high welding tensile strength, comprising components in the following mass percentages:

[0006] Silver powder: 75%-90%,

[0007] Nano bismuth powder: 1%-5%,

[0008] Resin: 3%-8%,

[0009] Organic solvent: 3%-8%,

[0010] Curing agent: 0.1%-1%,

[0011] Dispersant: 0.2%-1%,

[0012] Adhesion promoter: 0.5%-2%.

[0013] Furthermore, the nano bismuth powder is spherical powder, with an average particle size of 20-100 nm and a tapped density of 4-12 g / mL. In the present invention, the amount of bismuth powder accounts for 1%-5% of the total components. Excessive bismuth powder will cause an increase in resistance, and too little amount will not have an obvious effect on improving the welding tensile strength.

[0014] Further, the silver powder includes two types of silver powder, namely flaky silver powder and spherical silver powder. The particle size distribution D50 of the flaky silver powder is 1.0 - 2.0 μm, and its tapped density is 4 - 7 g / mL; the particle size distribution D50 of the spherical silver powder is 1.5 - 3 μm, and its tapped density is 5 - 8 g / mL.

[0015] Further, the resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, acrylic modified epoxy resin, polyester resin, and acrylic resin.

[0016] Further, the organic solvent includes one or more of dibasic acid esters, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol butyl ether acetate, dimethyl adipate, terpineol, ethyl acetate, and butyl acetate.

[0017] Further, the curing agent includes one or more of dicyandiamide curing agents, imidazole curing agents, modified amine curing agents, and anhydride curing agents.

[0018] Further, the dispersant is selected from one or more of carboxylates, sulfonates, ammonium salts, polyesters, and polyurethanes.

[0019] Further, the adhesion promoter is selected from one or more of silane coupling agents, titanate coupling agents, aluminate coupling agents, and silicon-titanium composite coupling agents.

[0020] The present invention also provides a method for preparing the above-mentioned high welding tensile strength solar cell low-temperature silver paste, which includes the following steps:

[0021] S1. Take the resin, organic solvent, dispersant, and adhesion promoter, mix them, and put them into a centrifugal disperser for dispersion at a rotation speed of 800 - 1000 r / min for 1 - 3 min to obtain a mixed slurry;

[0022] S2. Mix the mixed slurry with the curing agent and stir at a low speed, with a stirring speed of 100 - 200 r / min, to obtain an organic carrier;

[0023] S3. Add the silver powder and nano bismuth powder to the organic carrier in batches, while stirring, with a stirring speed of 100 - 200 r / min, to obtain a preliminarily dispersed conductive silver paste slurry;

[0024] S4. Put the conductive silver paste slurry into a three-roll mill for rolling the slurry multiple times, generally 6 - 8 times, to obtain a conductive silver paste with a fineness < 8 μm and a viscosity of 50 - 150 Pa·s.

[0025] Further, in steps S2 and S3, the temperature is controlled to be less than 20°C during stirring.

[0026] During the experiment, the researchers unexpectedly found that adding a certain amount of nano-bismuth powder to the low-temperature silver paste could change the properties of the silver paste. After melting, the nano-bismuth powder had excellent adhesion to both the substrate and silver, and the welding tensile strength of the silver paste could be significantly improved. Therefore, the present invention innovatively developed a low-temperature conductive silver paste for high-welding-tensile-strength solar cells. Experimental tests have proven that the welding tensile strength of the low-temperature silver paste provided by the present invention reaches a leading level, has a wider applicability to the welding of HJT cell wafers, and improves the lifespan of HJT cell modules. Detailed Implementation Modes

[0027] The technical solution of the present invention will be described in detail below through examples, but the protection scope of the present invention is not limited to the described examples. Unless otherwise specified, the raw materials in the present invention are all commercially available.

[0028] In the following examples, the silver powder used has a particle size distribution D50 of 1.0 - 2.0 μm and a tapped density of 4 - 7 g / mL; the nano-bismuth powder is spherical powder with an average particle size of 50 nm and a tapped density of 4 - 12 g / mL.

[0029] D50: The particle size at which the cumulative particle distribution is 50%. Also known as the median diameter or median particle size, this is a typical value representing the particle size. This value accurately divides the whole into two equal parts, that is, 50% of the particles exceed this value and 50% of the particles are below this value. If the D50 of a sample = 5 μm, it means that among all the particles with different particle sizes that make up the sample, 50% of the particles are larger than 5 μm and 50% of the particles are smaller than 5 μm.

[0030] Example 1

[0031] A low-temperature silver paste for high-welding-tensile-strength solar cells of the present invention contains the following components by mass:

[0032] 82 g of silver powder,

[0033] 5 g of nano-bismuth powder,

[0034] 5 g of bisphenol A epoxy resin,

[0035] 5 g of diethylene glycol butyl ether,

[0036] 1 g of dicyandiamide latent curing agent,

[0037] 1 g of polyester dispersant STA - 1648A,

[0038] 1 g of silane coupling agent KH550;

[0039] Among them, the nano-bismuth powder is spherical powder with an average particle size of 27 nm and a tapped density of 4.5 g / mL; the silver powder includes two types of silver powder, flaky silver powder and spherical silver powder. The particle size distribution D50 of the flaky silver powder is 1.7 μm and the tapped density is 5.8 g / mL; the particle size distribution D50 of the spherical silver powder is 2.1 μm and the tapped density is 6.3 g / mL.

[0040] The preparation method of the low-temperature silver paste for high-welding-tensile-force solar cells in this embodiment includes the following steps:

[0041] S1. Take 5 g of bisphenol A epoxy resin, 5 g of diethylene glycol butyl ether, 1 g of polyester dispersant STA-1648A, and 1 g of silane coupling agent KH550, mix them, put them into a centrifugal disperser for dispersion, with a rotation speed of 1000 r / min and a time of 1 min to obtain a mixed slurry;

[0042] S2. Mix the mixed slurry with 1 g of dicyandiamide latent curing agent, stir at a low speed, with a stirring speed of 100 r / min, and control the temperature at 15 °C to obtain an organic carrier;

[0043] S3. Add 82 g of silver powder and 5 g of nano-bismuth powder to the organic carrier in 4 times, stir while adding, with a stirring speed of 100 - 200 r / min, and control the temperature at 15 °C to obtain a preliminarily dispersed conductive silver paste slurry;

[0044] S4. Put the conductive silver paste slurry into a three-roll mill for rolling 6 times to obtain the low-temperature conductive silver paste of the present invention.

[0045] Example 2

[0046] A low-temperature silver paste for high-welding-tensile-force solar cells of the present invention contains the following components by mass:

[0047] 80 g of silver powder,

[0048] 3 g of nano-bismuth powder,

[0049] 8 g of acrylic acid-modified epoxy resin,

[0050] 6 g of terpineol,

[0051] 0.5 g of modified amine type latent curing agent T31,

[0052] 0.5 g of polyurethane S85,

[0053] 2 g of silane coupling agent KH560;

[0054] Among them, the nano bismuth powder is spherical powder with an average particle size of 48 nm and a tapped density of 6.1 g / mL; the silver powder includes two types of silver powder, flaky silver powder and spherical silver powder. The particle size distribution D50 of the flaky silver powder is 1.2 μm and the tapped density is 4.3 g / mL; the particle size distribution D50 of the spherical silver powder is 1.8 μm and the tapped density is 6.1 g / mL.

[0055] The preparation method of the low-temperature silver paste for high-welding-tensile solar cells in this embodiment includes the following steps:

[0056] S1. Take 8 g of acrylic acid modified epoxy resin, 6 g of terpineol, 0.5 g of polyurethane S85, and 2 g of silane coupling agent KH560, mix them, and put them into a centrifugal disperser for dispersion at a rotation speed of 1000 r / min for 1 min to obtain a mixed slurry.

[0057] S2. Mix the mixed slurry with 0.5 g of modified amine latent curing agent T31, stir at a low speed with a stirring speed of 100 r / min, and control the temperature at 15 °C to obtain an organic carrier.

[0058] S3. Add 80 g of silver powder and 3 g of nano bismuth powder to the organic carrier in 5 portions, stir while adding, with a stirring speed of 100 - 200 r / min, and control the temperature at 15 °C to obtain a preliminarily dispersed conductive silver paste slurry.

[0059] S4. Put the conductive silver paste slurry into a three-roll mill for rolling 6 times to obtain the low-temperature conductive silver paste of the present invention.

[0060] Example 3

[0061] A low-temperature silver paste for high-welding-tensile solar cells of the present invention contains the following components by mass:

[0062] 90 g of silver powder,

[0063] 2 g of nano bismuth powder,

[0064] 3 g of polyester resin,

[0065] 1 g of bisphenol F epoxy resin,

[0066] 3.2 g of DBE organic solvent,

[0067] 0.1 g of 2-ethyl-4-methylimidazole,

[0068] 0.2 g of carboxylate dispersant BP5040,

[0069] 0.5 g of titanate coupling agent GR105;

[0070] The nano bismuth powder is spherical powder with an average particle size of 79 nm and a tapped density of 7.3 g / mL; the silver powder includes two kinds of silver powder, flaky silver powder and spherical silver powder. The particle size distribution D50 of the flaky silver powder is 2.0 μm and the tapped density is 6.7 g / mL; the particle size distribution D50 of the spherical silver powder is 2.3 μm and the tapped density is 6.4 g / mL.

[0071] The preparation method of the low-temperature silver paste for high-welding-tensile-force solar cells in this embodiment includes the following steps:

[0072] S1. Take 3 g of polyester resin, 1 g of bisphenol F epoxy resin, 3.2 g of DBE organic solvent, 0.2 g of carboxylate dispersant BP5040, and 0.5 g of titanate coupling agent GR105, mix them, put them into a centrifugal disperser for dispersion, with a rotation speed of 1000 r / min and a time of 1 min to obtain a mixed slurry;

[0073] S2. Mix the mixed slurry with 0.1 g of imidazole curing agent 2-ethyl-4-methylimidazole, stir at a low speed with a stirring speed of 100 r / min, and control the temperature at 15 °C to obtain an organic carrier;

[0074] S3. Add 90 g of silver powder and 2 g of nano bismuth powder to the organic carrier in 3 times, stir while adding, with a stirring speed of 200 r / min, and control the temperature at 15 °C to obtain a preliminarily dispersed conductive silver paste slurry;

[0075] S4. Put the conductive silver paste slurry into a three-roll mill for rolling 8 times to obtain the low-temperature conductive silver paste of the present invention.

[0076] Example 4

[0077] A low-temperature silver paste for high-welding-tensile-force solar cells contains components with the following masses:

[0078] 75 g of silver powder,

[0079] 5 g of nano bismuth powder,

[0080] 5 g of acrylic resin,

[0081] 3 g of bisphenol A epoxy resin,

[0082] 8 g of dimethyl adipate,

[0083] 1 g of dicyandiamide latent curing agent,

[0084] 1 g of ammonium salt Dispersant 5029 dispersant,

[0085] 2 g of aluminate coupling agent;

[0086] The nano bismuth powder is spherical powder with an average particle size of 92 nm and a tapped density of 10.8 g / mL; the silver powder includes two kinds of silver powder, flaky silver powder and spherical silver powder. The particle size distribution D50 of the flaky silver powder is 1.4 μm and the tapped density is 5.1 g / mL; the particle size distribution D50 of the spherical silver powder is 2.8 μm and the tapped density is 7.7 g / mL.

[0087] The preparation method of the low-temperature silver paste for high-welding-tensile solar cells in this embodiment includes the following steps:

[0088] S1. Take 5 g of acrylic resin, 3 g of bisphenol A epoxy resin, 8 g of dimethyl adipate, 1 g of ammonium salt Dispersant5029 dispersant, and 2 g of aluminate coupling agent, mix them, put them into a centrifugal disperser for dispersion, with a rotation speed of 1000 r / min and a time of 1 min to obtain a mixed slurry;

[0089] S2. Mix the mixed slurry with 1 g of dicyandiamide latent curing agent, stir at a low speed, with a stirring speed of 100 r / min, and control the temperature at 15 °C to obtain an organic carrier;

[0090] S3. Add 75 g of silver powder and 5 g of nano bismuth powder to the organic carrier in 5 times, stir while adding, with a stirring speed of 150 r / min, and control the temperature at 15 °C to obtain a preliminarily dispersed conductive silver paste slurry;

[0091] S4. Put the conductive silver paste slurry into a three-roll mill for rolling 6 times to obtain the low-temperature conductive silver paste of the present invention.

[0092] Comparative Example 1

[0093] A kind of low-temperature silver paste for solar cells includes the following components by mass:

[0094] 87 g of silver powder,

[0095] 5 g of bisphenol A epoxy resin,

[0096] 5 g of diethylene glycol butyl ether,

[0097] 1 g of dicyandiamide latent curing agent,

[0098] 1 g of polyester dispersant STA-1648A,

[0099] 1 g of silane coupling agent KH550;

[0100] Among them, the silver powder includes two kinds of silver powder, flaky silver powder and spherical silver powder. The particle size distribution D50 of the flaky silver powder is 1.7 μm and the tapped density is 5.8 g / mL. The particle size distribution D50 of the spherical silver powder is 2.1 μm and the tapped density is 6.3 g / mL.

[0101] The method for preparing low-temperature silver paste for solar cells in this comparative example includes the following steps:

[0102] S1. Take 5 g of bisphenol A epoxy resin, 5 g of diethylene glycol butyl ether, 1 g of polyester dispersant STA-1648A, and 1 g of silane coupling agent KH550, mix them, and put them into a centrifugal disperser for dispersion at a rotation speed of 1000 r / min for 1 min to obtain a mixed slurry;

[0103] S2. Mix the mixed slurry with 1 g of dicyandiamide latent curing agent, stir at a low speed with a stirring speed of 100 r / min, and control the temperature at 15 °C to obtain an organic carrier;

[0104] S3. Add 87 g of silver powder to the organic carrier in 4 portions, stir while adding, with a stirring speed of 100 - 200 r / min, and control the temperature at 15 °C to obtain a preliminarily dispersed conductive silver paste slurry;

[0105] S4. Put the conductive silver paste slurry into a three-roll mill for rolling 6 times to obtain low-temperature conductive silver paste.

[0106] Comparative Example 2

[0107] A low-temperature silver paste for solar cells includes components with the following masses:

[0108] 83 g of silver powder,

[0109] 8 g of acrylic acid-modified epoxy resin,

[0110] 6 g of terpineol,

[0111] 0.5 g of polyurethane S850,

[0112] 2 g of silane coupling agent KH560,

[0113] 0.5 g of modified amine type latent curing agent T31;

[0114] Among them, the silver powder includes two types of silver powder: flaky silver powder and spherical silver powder. The particle size distribution D50 of the flaky silver powder is 1.2 μm, and the tapped density is 4.3 g / mL; the particle size distribution D50 of the spherical silver powder is 1.8 μm, and the tapped density is 6.1 g / mL.

[0115] The method for preparing low-temperature silver paste for solar cells in this comparative example includes the following steps:

[0116] S1. Take 8 g of acrylic acid-modified epoxy resin, 6 g of terpineol, 0.5 g of polyurethane S85, and 2 g of silane coupling agent KH560, mix them, and put them into a centrifugal disperser for dispersion at a rotation speed of 1000 r / min for 1 min to obtain a mixed slurry;

[0117] S2. Mix the mixed slurry with 0.5 g of modified amine latent curing agent T31, stir at a low speed, with a stirring speed of 100 r / min, and control the temperature at 15 °C to obtain an organic carrier;

[0118] S3. Add 83 g of silver powder to the organic carrier in 5 portions, stir while adding, with a stirring speed of 100 - 200 r / min, and control the temperature at 15 °C to obtain a preliminarily dispersed conductive silver paste slurry;

[0119] S4. Put the conductive silver paste slurry into a three-roll mill and roll the slurry 6 times to obtain a low-temperature conductive silver paste.

[0120] Comparative Example 3

[0121] A low-temperature silver paste for solar cells comprises components with the following masses:

[0122] 92 g of silver powder,

[0123] 3 g of polyester resin,

[0124] 1 g of bisphenol F epoxy resin,

[0125] 3.2 g of DBE organic solvent,

[0126] 0.2 g of carboxylate dispersant BP5040,

[0127] 0.5 g of titanate coupling agent GR105,

[0128] 0.1 g of 2-ethyl-4-methylimidazole;

[0129] Among them, the silver powder includes two types of silver powder, flaky silver powder and spherical silver powder. The particle size distribution D50 of the flaky silver powder is 2.0 μm, and the tapped density is 6.7 g / mL; the particle size distribution D50 of the spherical silver powder is 2.3 μm, and the tapped density is 6.4 g / mL.

[0130] The method for preparing the low-temperature silver paste for solar cells in this comparative example includes the following steps:

[0131] S1. Take 3 g of polyester resin, 1 g of bisphenol F epoxy resin, 3.2 g of DBE organic solvent, 0.2 g of carboxylate dispersant BP5040, and 0.5 g of titanate coupling agent GR105 and mix them, put them into a centrifugal disperser for dispersion, with a rotation speed of 1000 r / min and a time of 1 min to obtain a mixed slurry;

[0132] S2. Mix the mixed slurry with 0.1 g of imidazole curing agent 2-ethyl-4-methylimidazole, stir at a low speed, with a stirring speed of 100 r / min, and control the temperature at 15 °C to obtain an organic carrier;

[0133] S3. Add 92 g of silver powder to the organic carrier in three portions, with stirring during addition. The stirring speed is 200 r / min, and the temperature is controlled at 15 °C to obtain a preliminarily dispersed conductive silver paste slurry.

[0134] S4. Place the conductive silver paste slurry into a three-roll mill and roll it 8 times to obtain a low-temperature conductive silver paste.

[0135] Comparative Example 4

[0136] A low-temperature silver paste for solar cells contains the following components by mass:

[0137] 80 g of silver powder,

[0138] 5 g of acrylic resin,

[0139] 3 g of bisphenol A epoxy resin,

[0140] 8 g of dimethyl adipate,

[0141] 1 g of Dispersant 5029 dispersant (ammonium salt),

[0142] 2 g of aluminate coupling agent,

[0143] 1 g of dicyandiamide latent curing agent;

[0144] The silver powder includes two types of silver powder: flaky silver powder and spherical silver powder. The particle size distribution D50 of the flaky silver powder is 1.4 μm, and the tapped density is 5.1 g / mL; the particle size distribution D50 of the spherical silver powder is 2.8 μm, and the tapped density is 7.7 g / mL.

[0145] The method for preparing the low-temperature silver paste for solar cells in this comparative example includes the following steps:

[0146] S1. Take 5 g of acrylic resin, 3 g of bisphenol A epoxy resin, 8 g of dimethyl adipate, 1 g of Dispersant 5029 dispersant (ammonium salt), and 2 g of aluminate coupling agent, mix them, and place them in a centrifugal disperser for dispersion at a rotation speed of 1000 r / min for 1 min to obtain a mixed slurry.

[0147] S2. Mix the mixed slurry with 1 g of dicyandiamide latent curing agent, and stir at a low speed. The stirring speed is 100 r / min, and the temperature is controlled at 15 °C to obtain an organic carrier.

[0148] S3. Add 80 g of silver powder to the organic carrier in five portions, with stirring during addition. The stirring speed is 150 r / min, and the temperature is controlled at 15 °C to obtain a preliminarily dispersed conductive silver paste slurry.

[0149] S4. Place the conductive silver paste slurry into a three-roll mill and roll it 6 times to obtain a low-temperature conductive silver paste.

[0150] The solder paste prepared in the above Examples 1-4 and Comparative Examples 1-4 was tested for welding tensile performance. The test method is as follows:

[0151] Immerse the solder tape in the flux for 1 min, and set the soldering iron temperature to 240 °C;

[0152] Use screen printing to print a line pattern of the solder paste on the surface of the ITO silicon wafer;

[0153] Take out the solder tape, align the solder tape with the line;

[0154] Dip a small amount of solder with the soldering iron and push it along the solder tape to weld the solder tape to the solder paste;

[0155] Bend the excess solder tape and fix it on the handheld tensile testing machine. After zeroing the instrument data, pull it evenly and read the test peak data after each pull;

[0156] Remove the maximum and minimum values from a series of data, and take the average of the remaining data to obtain the welding tensile test data. The welding tensile performance test results of the low-temperature solder paste prepared in Examples 1-4 and Comparative Examples 1-4 are shown in Table 1.

[0157] Table 1

[0158] Project Welding Tensile Strength Project Welding Tensile Strength Example 1 2.5 Comparative Example 1 0.8 Example 2 2.0 Comparative Example 2 0.6 Example 3 1.6 Comparative Example 3 0.5 Example 4 2.2 Comparative Example 4 0.6

[0159] It can be seen from the test results in Table 1 that by adding an appropriate amount of nano-bismuth powder to the solder paste in the present invention, the welding tensile strength of the solder paste is improved. Compared with the ordinary low-temperature solder paste, the welding tensile strength is increased by more than 3 times. Applying this solder paste to the HJT battery can greatly improve the service life of the battery.

Claims

1. A low-temperature silver paste for high-welding-tensile solar cells, characterized in that, The silver paste contains components in the following mass percentages: Silver powder: 75%-90%, Nano bismuth powder: 1%-5%, Resin: 3%-8%, Organic solvent: 3%-8%, Curing agent: 0.1%-1%, Dispersant: 0.2%-1%, Adhesion promoter: 0.5%-2%; Its preparation method includes the following steps: S1. Take resin, organic solvent, dispersant, and adhesion promoter, mix them, and disperse them in a centrifugal disperser to obtain a mixed slurry; S2. Mix the mixed slurry with the curing agent and stir at a low speed to obtain an organic carrier; S3. Add silver powder and nano bismuth powder to the organic carrier in batches, stirring while adding, to obtain a preliminarily dispersed conductive silver paste slurry; S4. Roll the conductive silver paste slurry to obtain a conductive silver paste.

2. The low-temperature silver paste for high-welding-tensile solar cells according to claim 1, wherein The nano bismuth powder is spherical powder, with an average particle size of 20-100 nm and a tapped density of 4-12 g / mL.

3. The low-temperature silver paste for high-welding-tensile solar cells according to claim 1, wherein The silver powder includes two types of silver powder, flaky silver powder and spherical silver powder. The particle size distribution D50 of the flaky silver powder is 1.0-2.0 μm, and the tapped density is 4-7 g / mL; the particle size distribution D50 of the spherical silver powder is 1.5-3 μm, and the tapped density is 5-8 g / mL.

4. The low-temperature silver paste for high-welding-tensile solar cells according to claim 1, wherein The resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, acrylic modified epoxy resin, polyester resin, and acrylic resin.

5. The low-temperature silver paste for high-welding-tensile solar cells according to claim 1, wherein The organic solvent includes one or more of dibasic acid ester, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol butyl ether acetate, dimethyl adipate, terpineol, ethyl acetate, and butyl acetate.

6. The low-temperature silver paste for high soldering tensile strength solar cells according to claim 1, wherein The curing agent includes one or more of dicyandiamide curing agent, imidazole curing agent, modified amine curing agent, and anhydride curing agent.

7. The low-temperature silver paste for high soldering tensile strength solar cells according to claim 1, wherein, The dispersant is selected from one or more of carboxylate, sulfonate, ammonium salt, polyester, and polyurethane.

8. The low-temperature silver paste for high-welding-tensile solar cells according to claim 1, wherein The adhesion promoter is selected from one or more of silane coupling agent, titanate coupling agent, aluminate, and silicon-titanium composite coupling agent.

9. The low-temperature silver paste for high-welding-tensile solar cells according to any one of claims 1-8, characterized in that In steps S2 and S3 of its preparation method, the temperature is controlled to be less than 20 °C during stirring.