Seed layer paste for topcon cell and method for preparing the same

Abstract

This invention discloses a seed layer slurry for TOPCon batteries and its preparation method. The seed layer slurry comprises the following components by weight percentage: 0.5-5 wt% nano-silver powder, 35-70 wt% micron-sized silver powder, 5-30 wt% carbon-based ternary composite powder, 4-6.5 wt% glass powder, 3-9 wt% organic resin, 1-20 wt% organic solvent, 0.1-2 wt% silicone oil, and 0.1-1 wt% additives. The carbon-based ternary composite powder comprises a base phase and a functional phase. The functional phase is combined with the base phase through coating and / or embedding to form an integrated composite structure. The base phase is a carbon nanocomposite material, and the functional phase includes at least two of base metals, oxides, and borides. The slurry of this invention achieves low silver loss and high bonding strength while maintaining the high performance and long-term reliability of the battery.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a seed layer paste for TOPCon cells and its preparation method. Background Technology

[0002] Traditional TOPCon cells use all-silver paste grid lines, resulting in high silver consumption and persistently high non-silicon costs. To reduce costs, the industry has explored a "low-silver seed layer + silver-clad copper stacked grid" technical solution. This solution uses a bottom seed layer to ensure contact stability, while the top silver-clad copper layer replaces a large amount of silver powder and is compatible with existing screen printing production lines. However, this solution has a key bottleneck: the seed layer needs to balance low silver consumption, high-temperature compatibility with silver-clad copper, and copper diffusion blocking ability. Existing materials are difficult to meet these requirements simultaneously, leading to problems such as increased contact resistance and interlayer delamination. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a seed layer slurry for TOPCon batteries and a method for preparing the same, in order to overcome the shortcomings of the above-mentioned prior art, meet the requirements of low silver consumption and high bonding strength, while maintaining the high performance and long-term reliability of the battery.

[0004] This invention provides a seed layer slurry for TOPCon batteries, comprising the following components by weight percentage: 0.5-5 wt% nano-silver powder, 35-70 wt% micron-sized silver powder, 5-30 wt% carbon-based ternary composite powder, 4-6.5 wt% glass powder, 3-9 wt% organic resin, 1-20 wt% organic solvent, 0.1-2 wt% silicone oil, and 0.1-1 wt% additives; wherein the carbon-based ternary composite powder comprises a base phase and a functional phase, the functional phase being combined with the base phase by coating and / or embedding to form an integrated composite structure; the base phase is a carbon nanocomposite material, and the functional phase comprises at least two of base metals, oxides, and borides.

[0005] Furthermore, the carbon nanocomposite material is composed of multiple carbon nanotubes as basic units, with each carbon nanotube having a diameter of 10-50 nm and a length of 3-5 μm; wherein, the carbon nanotubes are connected by van der Waals forces and some in-situ formed carbon-carbon covalent bonds to form a dense structure, and the carbon nanocomposite material has a density ≤2.0 g / cm³ and a porosity ≤2%.

[0006] Further, the base metal includes at least one of copper, tungsten, tin, nickel, and aluminum; and / or, the oxide includes at least one of silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, and boron oxide; and / or, the boride includes at least one of titanium boride, tungsten boride, and zirconium boride.

[0007] Furthermore, the carbon-based ternary composite powder includes one or more of the following: carbon-nickel-silver ternary composite powder, carbon-copper-silicon oxide ternary composite powder, and carbon-silver-zirconium boride ternary composite powder.

[0008] Furthermore, in the carbon-copper-silicon oxide ternary composite powder, the mass ratio of carbon nanocomposite material, copper, and silicon oxide is 3:5:2.

[0009] Furthermore, the nano-silver powder is a single-peak spherical silver powder with a D50 of 220-550 nm and a tap density of 5.5-8.8 g / cm³. 3 Its specific surface area is 1.0-1.95 m². 2 / g; the micron-sized silver powder is a single-peak spherical silver powder with a D50 of 1.2-1.8μm and a tap density of 4.5-7.5g / cm³. 3 Its specific surface area is 0.25-0.85 m². 2 / g.

[0010] Furthermore, the preparation method of the carbon-based ternary composite powder includes at least one of the following: ultrasonic dispersion-vacuum drying method, low-temperature ball milling-inert sintering method, gas atomization-in-situ growth method, and chemical plating coating method.

[0011] Furthermore, the ultrasonic dispersion-vacuum drying method includes the following steps:

[0012] Pre-treat the base phase and functional phase, remove impurities from the base phase and passivate and / or modify the functional phase;

[0013] Weigh the pretreated base phase and functional phase according to the ratio, add them to the dispersion, and mix to obtain a mixed slurry with a solid content of 30%-50%.

[0014] The above-mentioned mixed slurry was ultrasonically dispersed at 50-90 kHz and 200-600 W for 50-70 min, and then centrifuged to remove impurities and concentrate until the solid content was 60%-70%.

[0015] The concentrated mixed slurry was vacuum dried at 60-100℃ for 7-11 hours to obtain a dried mixed powder.

[0016] Under an inert atmosphere, the dried mixed powder is heat-treated at 300-320℃ for 1-2 hours, cooled, pulverized and sieved to obtain the desired carbon-based ternary composite powder.

[0017] Furthermore, the low-temperature ball milling-inert sintering method includes the following steps:

[0018] The basic phase and functional phase are pretreated by removing impurities from the surface of the basic phase and passivating and / or modifying the surface of the functional phase.

[0019] Weigh the pretreated base phase and functional phase according to the ratio and add them to the dispersion. Control the material temperature ≤50℃ during ball milling. After ball milling for 3-6 hours, vacuum dry at 60-70℃ for 5-8 hours to obtain ball-milled dried mixed powder.

[0020] Under an inert atmosphere, the ball-milled and dried mixed powder is sintered at 500-800℃ for 1-2 hours, cooled, pulverized and sieved to obtain the desired carbon-based ternary composite powder.

[0021] The present invention also provides a method for preparing the seed layer slurry for TOPCon batteries as described above, comprising the following steps:

[0022] After weighing the nano silver powder, micron silver powder, carbon-based ternary composite powder, glass powder, organic resin, organic solvent, silicone oil, and additives according to the specified ratio, add them to the reaction apparatus and mix and stir evenly.

[0023] Then, the mixture is ground using a three-roll mill with a grinding interval of 10-120μm and a grinding speed of 50-400r / min to obtain a seed layer slurry with a fineness of ≤5μm.

[0024] The beneficial effects of this invention are as follows: By introducing a specific proportion of carbon-based ternary composite powder, the expensive and high-density micron-sized silver powder in traditional formulations can be partially replaced. This composite powder uses a highly conductive and lightweight carbon nanocomposite material as the base phase, tightly bonded to at least two functional phases (including base metals, oxides, or borides) through coating / embedding, thereby constructing a novel, multifunctional composite conductive and bonding network in the slurry. By replacing 10%-30% of the seed layer silver powder with carbon-based ternary composite powder, the overall silver consumption of the "low-silver seed layer + silver-coated copper grid" scheme is further reduced while ensuring conductivity, effectively controlling the non-silicon cost of the battery. The synergistic effect of the ternary components not only enhances the interfacial bonding force between the seed layer and the passivation layer and the silver-coated copper layer, but also reduces contact resistance and blocks copper ion diffusion, avoiding interlayer delamination and battery structural damage; thus maintaining the high performance and long-term reliability of the battery. Detailed Implementation

[0025] This invention provides a seed layer slurry for TOPCon batteries. By weight percentage, the seed layer slurry comprises the following components: 0.5-5 wt% nano silver powder, 35-70 wt% micron silver powder, 5-30 wt% carbon-based ternary composite powder, 4-6.5 wt% glass powder, 3-9 wt% organic resin, 1-20 wt% organic solvent, 0.1-2 wt% silicone oil, and 0.1-1 wt% additives. The carbon-based ternary composite powder comprises a base phase and a functional phase. The functional phase is combined with the base phase by coating and / or embedding to form an integrated composite structure. The base phase is a carbon nanocomposite material, and the functional phase comprises at least two of base metals, oxides, and borides.

[0026] In this embodiment, a specific proportion of carbon-based ternary composite powder is introduced to partially replace the expensive and high-density micron-sized silver powder in traditional formulations. This composite powder uses a highly conductive and lightweight carbon nanocomposite material as the base phase, tightly bonded to at least two functional phases (including base metals, oxides, or borides) through coating / embedding, thereby constructing a novel, multifunctional composite conductive and bonding network in the slurry. By replacing 10%-30% of the seed layer silver powder with carbon-based ternary composite powder, the overall silver consumption of the "low-silver seed layer + silver-coated copper grid" scheme is further reduced while ensuring conductivity, effectively controlling the non-silicon cost of the battery. The synergistic effect of the ternary components not only enhances the interfacial bonding force between the seed layer and the passivation layer and the silver-coated copper layer, but also reduces contact resistance and blocks copper ion diffusion, avoiding interlayer delamination and battery structural damage; thus maintaining the high performance and long-term reliability of the battery.

[0027] Furthermore, the carbon nanocomposite material is composed of multiple carbon nanotubes as basic units, with each carbon nanotube having a diameter of 10-50 nm and a length of 3-5 μm. The carbon nanotubes are connected by van der Waals forces and partially in-situ formed carbon-carbon covalent bonds, forming a dense structure. The carbon nanocomposite material has a density ≤2.0 g / cm³ and a porosity ≤2%. In some preferred embodiments of the present invention, the carbon nanocomposite material can be a commercially available dense composite material composed of carbon nanotubes. For example, Galvorn material produced by DexMat can be used as the base phase. This commercial material has structural characteristics suitable for the requirements of this application: its individual carbon nanotubes have a diameter of approximately 10-50 nm and a length of approximately 3-5 μm, a bulk density ≤2.0 g / cm³, and a low porosity (typically ≤2%), enabling the effective construction of a three-dimensional conductive network. It should be noted that the selection of this commercial product is merely an example; any carbon nanocomposite material with similar structural characteristics and performance parameters is applicable to the present invention. In the subsequent embodiments and comparative examples of this invention, the carbon nanocomposite material used is Galvorn.

[0028] Furthermore, the base metal includes at least one of copper, tungsten, tin, nickel, and aluminum; and / or, the oxide includes at least one of silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, and boron oxide; and / or, the boride includes at least one of titanium boride, tungsten boride, and zirconium boride.

[0029] Furthermore, the carbon-based ternary composite powder includes one or more of the following: carbon-nickel-silver ternary composite powder, carbon-copper-silicon oxide ternary composite powder, and carbon-silver-zirconium boride ternary composite powder. Copper (a highly conductive base metal with conductivity close to that of silver) replaces a portion of the silver powder, reducing costs. Silica acts as a dispersed phase to inhibit copper particle agglomeration. The addition of silica ensures that the printability (viscosity, thixotropy) of the paste is highly compatible with existing processes. Galvorn builds a cross-particle conductive bridge—the synergy of these three components allows the composite powder to retain conductivity close to that of pure silver. Nickel (high temperature resistance, strong compatibility) forms an alloyed conductive phase with silver, preventing softening and deformation of the metal phase during sintering and reducing interfacial contact resistance. Galvorn supplements the conductive pathway and improves the mechanical stability of the paste—the combination of these three components allows the composite powder to directly replace 10%-30% of the silver powder without modifying the existing silver paste formulation and sintering process. Zirconium boride (high hardness, diffusion resistance, and high temperature resistance) inhibits silver atom migration and interfacial diffusion, Galvorn improves the thermal conductivity of the paste, and silver, as the dominant conductive phase, ensures low resistance—the three work together to solve the problems of diffusion resistance and wear resistance of silver paste under high-temperature sintering.

[0030] Furthermore, in the carbon-copper-silicon oxide ternary composite powder, the mass ratio of carbon nanocomposite material, copper, and silicon oxide is 3:5:2.

[0031] Furthermore, the nano-silver powder is a single-peak spherical silver powder with a D50 of 220-550 nm and a tap density of 5.5-8.8 g / cm³. 3 Its specific surface area is 1.0-1.95 m². 2 / g; the micron-sized silver powder is a single-peak spherical silver powder with a D50 of 1.2-1.8μm and a tap density of 4.5-7.5g / cm³. 3 Its specific surface area is 0.25-0.85 m². 2 / g.

[0032] Furthermore, the preparation methods of carbon-based ternary composite powder include at least one of ultrasonic dispersion-vacuum drying, low-temperature ball milling-inert sintering, gas atomization-in-situ growth, and chemical plating coating.

[0033] Furthermore, the ultrasonic dispersion-vacuum drying method includes the following steps:

[0034] Pre-treat the base phase and functional phase, remove impurities from the base phase and passivate and / or modify the functional phase;

[0035] Weigh the pretreated base phase and functional phase according to the ratio, add them to the dispersion, and mix to obtain a mixed slurry with a solid content of 30%-50%.

[0036] The above-mentioned mixed slurry was ultrasonically dispersed at 50-90 kHz and 200-600 W for 50-70 min, and then centrifuged to remove impurities and concentrate until the solid content was 60%-70%.

[0037] The concentrated mixed slurry was vacuum dried at 60-100℃ for 7-11 hours to obtain a dried mixed powder.

[0038] Under an inert atmosphere, the dried mixed powder is heat-treated at 300-320℃ for 1-2 hours, cooled, pulverized and sieved to obtain the desired carbon-based ternary composite powder.

[0039] Furthermore, the ultrasonic dispersion was performed in a dual-frequency, segmented manner, including ultrasonication at a frequency of 50-70 kHz for 20-30 minutes, followed by ultrasonication at a frequency of 70-90 kHz for 30-50 minutes. The entire process was carried out at a constant temperature of 35-40℃ with intermittent stirring to ensure thorough dispersion of the powder and prevent agglomeration.

[0040] In the ultrasonic dispersion-vacuum drying method, the dispersion includes a dispersion medium and a dispersant. The dispersion medium includes low-boiling-point organic solvents such as anhydrous ethanol and isopropanol, and deionized water is also commonly used, as it is suitable for carbon-based powders and facilitates subsequent vacuum drying removal. Dispersants include, but are not limited to, polyvinylpyrrolidone (PVP), oleic acid, sodium dodecylbenzenesulfonate (SDBS), and triethanolamine, which effectively prevent the agglomeration of Galvorn powder with the functional phase powder.

[0041] Furthermore, the low-temperature ball milling-inert sintering method includes the following steps:

[0042] The basic phase and functional phase are pretreated by removing impurities from the surface of the basic phase and passivating and / or modifying the surface of the functional phase.

[0043] Weigh the pretreated base phase and functional phase according to the ratio and add them to the dispersion. Control the material temperature ≤50℃ during ball milling. After ball milling for 3-6 hours, vacuum dry at 60-70℃ for 5-8 hours to obtain ball-milled dried mixed powder.

[0044] Under an inert atmosphere, the ball-milled and dried mixed powder is sintered at 500-800℃ for 1-2 hours, cooled, pulverized and sieved to obtain the desired carbon-based ternary composite powder.

[0045] In the low-temperature ball milling-inert sintering method, the dispersion includes a dispersion medium and a dispersant. The dispersion medium includes low-boiling-point organic solvents such as anhydrous ethanol and isopropanol, and deionized water is also commonly used, as it is suitable for carbon-based powders and facilitates subsequent vacuum drying removal. Dispersants include, but are not limited to, polyvinylpyrrolidone (PVP), oleic acid, sodium dodecylbenzenesulfonate (SDBS), and triethanolamine, which effectively prevent the agglomeration of Galvorn powder and functional phase powders.

[0046] Furthermore, the inert atmosphere is nitrogen and / or argon, which can effectively isolate air during heat treatment, ball milling, and sintering, preventing oxidation of Galvorn powder and functional phase powders such as silver and copper powder, and ensuring stable powder performance.

[0047] Furthermore, the particle size of the carbon-based ternary composite powder is 0.3-5.0 μm.

[0048] Further, the organic resin includes one or more of polyvinyl butyral, acrylic resin, ethyl cellulose, cellulose acetate butyrate, rosin resin, and polyα-methylstyrene; the organic solvent includes any one or more of butyl carbitol, diethylene glycol butyl ether acetate, terpineol, diethylene glycol monobutyl ether, ethylene glycol phenyl ether acetate, dodecyl alcohol ester, dimethyl adipate, hexadecyl alcohol ester, isopropanol, benzyl benzoate, glyceryl triacetate, and tripropylene glycol butyl ether; the silicone oil includes at least one of polydimethylsiloxane, polymethylhydroxysiloxane, and polymethylethoxysiloxane; the additives include at least one of fatty acid polyoxyethylene ether, tallow-based propylene diamine oleate, silane coupling agent, titanate coupling agent, polyamide wax, polyethylene glycol, hydrogenated castor oil, lecithin, oleic acid, and polyvinylpyrrolidone; the glass powder may be selected from one or more of Na2O, Al2O3, SiO2, ZnO, PbO, and Bi2O3, but is not limited thereto. Na2O can be optionally supplemented with Na2CO3, which decomposes to form Na2O during the preparation and melting process.

[0049] The present invention also provides a method for preparing the seed layer slurry for TOPCon batteries as described above, comprising the following steps:

[0050] After weighing the nano silver powder, micron silver powder, carbon-based ternary composite powder, glass powder, organic resin, organic solvent, silicone oil, and additives according to the specified ratio, add them to the reaction apparatus and mix and stir evenly; the stirring time can be selected as 45 minutes to ensure that each component is uniformly wetted.

[0051] Then, the mixture is ground using a three-roll mill with a grinding interval of 10-120μm and a grinding speed of 50-400r / min to obtain a seed layer slurry with a fineness ≤5μm (tested by a FOG scraper fineness gauge).

[0052] The beneficial effects of this invention are:

[0053] 1. Significant cost reduction: By replacing 10%-30% of the seed layer silver powder with carbon-based ternary composite powder, the overall silver consumption of the "low silver seed layer + silver-clad copper grid" scheme is further reduced while ensuring conductivity, effectively controlling the non-silicon cost of the battery.

[0054] 2. Comprehensive performance optimization: The synergistic effect of the ternary components not only enhances the interfacial bonding force between the seed layer and the passivation layer and the silver-coated copper layer, but also reduces the contact resistance and blocks the diffusion of copper ions, thus avoiding interlayer delamination and damage to the battery structure.

[0055] 3. Strong process adaptability: The composite powder can be directly integrated into the existing seed layer slurry preparation process, perfectly adapting to screen printing, sintering at 500-800℃ and subsequent curing processes, without the need for additional special equipment, which facilitates industrialization and promotion.

[0056] 4. Enhanced Environmental Adaptability: Containing antioxidant / anti-sulfurization components, it can inhibit silver layer sulfation and copper core oxidation, reduce performance degradation under high temperature and high humidity environments, and extend battery service life. Specifically, the antioxidant / anti-sulfurization components include the aforementioned benzotriazole (stabilizing phase) that passivates copper powder. After sintering, it adsorbs onto the surface of the silver layer or coats the outside of the copper powder, forming a dense physical-chemical dual protective layer. This effectively blocks the diffusion of oxygen and sulfides into the conductive phase, thereby inhibiting silver layer sulfation and copper core oxidation, reducing battery performance degradation under high temperature and high humidity environments, and extending its service life.

[0057] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. In these embodiments, to demonstrate and verify the technical effects of the present invention, the carbon nanocomposite material is exemplarily selected from Galvorn material manufactured by DexMat.

[0058] Example 1

[0059] A seed layer slurry for TOPCon batteries, comprising the following components:

[0060] Nano silver powder (D50 250-450nm): 3%;

[0061] Micron-sized silver powder (D50 1.1-2.0μm): 57%;

[0062] Carbon-based ternary composite powder (D50 is 4-5μm): 10%; specifically, it is a ternary composite powder of Galvorn-copper-silicon oxide, with a mass ratio of Galvorn, copper and silicon oxide of 3:5:2.

[0063] Glass powder: 5.5%; by molar percentage, the specific components include: 40% TeO2, 30% PbO2, 12.5% ​​Bi2O3, 0.5% SiO2, 5% WO3, 5% ZnO, 5% Na2CO3, 2% Li2CO3;

[0064] Organic resins: 1.5% ethyl cellulose (Dow STD-100), 1.5% polyvinyl butyral resin (Kuraray B30H), and 2% acrylic resin (Mitsubishi BR116);

[0065] Additives: 0.3% oleic acid, 2.5% polyamide wax;

[0066] Silicone oil: Polydimethylsiloxane (viscosity 100 mPa·s) 0.8%;

[0067] Solvents: 6.9% ethylene glycol butyl ether benzoate, 5.5% diethylene glycol butyl ether acetate, and 3.5% dodecyl alcohol ester.

[0068] Preparation method of Galvorn-copper-silica ternary composite powder:

[0069] Pretreatment: Galvorn powder with a particle size of 3-5μm is purified by dilute hydrochloric acid, copper powder with a particle size of 1-3μm is passivated by benzotriazole, and silica powder with a particle size of 0.5-2μm is modified by KH550;

[0070] Weigh each pretreated material according to the mass ratio of Galvorn, copper, and silicon dioxide of 3:5:2, and dissolve it in anhydrous ethanol (with 0.3%-0.5% PVP added) at a solid-liquid ratio of 1:8.

[0071] Sonicated at 60kHz for 20 minutes + Sonicated at 80kHz for 40 minutes (with intermittent stirring at a constant temperature of 35-40℃).

[0072] The ternary composite powder of Galvorn-copper-silica is obtained by vacuum drying at -0.08~-0.09MPa and 70-80℃ for 8-10 hours, followed by heat treatment at 300℃ in an inert atmosphere for 1.5 hours, and then pulverizing it through a 200-mesh sieve.

[0073] Method for preparing slurry:

[0074] After weighing the nano silver powder, micron silver powder, carbon-based ternary composite powder, glass powder, organic resin, organic solvent, silicone oil, and additives according to the specified ratio;

[0075] Stir (e.g., for 45 minutes) to ensure that all materials are evenly wetted;

[0076] The material was ground using a three-roll mill with a grinding interval of 10-120 μm and a grinding speed of 50-400 r / min, ultimately yielding a slurry with a fineness of less than 5 μm as measured by an FOG scraper fineness gauge.

[0077] Example 2

[0078] A seed layer slurry for TOPCon batteries, comprising the following components:

[0079] Nano silver powder (D50 250-450nm): 3%;

[0080] Micron-sized silver powder (D50 1.1-2.0μm): 47%;

[0081] Carbon-based ternary composite powder (D50 is 4-5μm): 20%; specifically, it is a ternary composite powder of Galvorn-copper-silicon oxide, with a mass ratio of Galvorn, copper and silicon oxide of 3:5:2.

[0082] Glass powder: 5.5%; by molar percentage, the specific components include: 40% TeO2, 30% PbO2, 12.5% ​​Bi2O3, 0.5% SiO2, 5% WO3, 5% ZnO, 5% Na2CO3, 2% Li2CO3;

[0083] Organic resins: 1.5% ethyl cellulose (Dow STD-100), 1.5% polyvinyl butyral resin (Kuraray B30H), and 2% acrylic resin (Mitsubishi BR116);

[0084] Additives: 0.3% oleic acid, 2.5% polyamide wax;

[0085] Silicone oil: Polydimethylsiloxane (viscosity 100 mPa·s) 0.8%;

[0086] Solvents: 6.9% ethylene glycol butyl ether benzoate, 5.5% diethylene glycol butyl ether acetate, and 3.5% dodecyl alcohol ester.

[0087] The preparation method of Galvorn-copper-silica ternary composite powder and slurry is the same as in Example 1.

[0088] Example 3

[0089] A seed layer slurry for TOPCon batteries, comprising the following components:

[0090] Nano silver powder (D50 250-450nm): 3%;

[0091] Micron-sized silver powder (D50 1.1-2.0μm): 37%;

[0092] Carbon-based ternary composite powder (D50 is 4-5μm): 30%; specifically, it is a ternary composite powder of Galvorn-copper-silicon oxide, with a mass ratio of Galvorn, copper and silicon oxide of 3:5:2.

[0093] Glass powder: 5.5%; by molar percentage, the specific components include: 40% TeO2, 30% PbO2, 12.5% ​​Bi2O3, 0.5% SiO2, 5% WO3, 5% ZnO, 5% Na2CO3, 2% Li2CO3;

[0094] Organic resins: 1.5% ethyl cellulose (Dow STD-100), 1.5% polyvinyl butyral resin (Kuraray B30H), and 2% acrylic resin (Mitsubishi BR116);

[0095] Additives: 0.3% oleic acid, 2.5% polyamide wax;

[0096] Silicone oil: Polydimethylsiloxane (viscosity 100 mPa·s) 0.8%;

[0097] Solvents: 6.9% ethylene glycol butyl ether benzoate, 5.5% diethylene glycol butyl ether acetate, and 3.5% dodecyl alcohol ester.

[0098] The preparation method of Galvorn-copper-silica ternary composite powder and slurry is the same as in Example 1.

[0099] Example 4

[0100] A seed layer slurry for TOPCon batteries, comprising the following components:

[0101] Nano silver powder (D50 250-450nm): 3%;

[0102] Micron-sized silver powder (D50 1.1-2.0μm): 47%;

[0103] Carbon-based ternary composite powder (D50 is 4-5μm): 20%; specifically, it is a Galvorn-nickel-silver ternary composite powder, with a mass ratio of Galvorn, nickel and silver of 2:5:3.

[0104] Glass powder: 5.5%; by molar percentage, the specific components include: 40% TeO2, 30% PbO2, 12.5% ​​Bi2O3, 0.5% SiO2, 5% WO3, 5% ZnO, 5% Na2CO3, 2% Li2CO3;

[0105] Organic resins: 1.5% ethyl cellulose (Dow STD-100), 1.5% polyvinyl butyral resin (Kuraray B30H), and 2% acrylic resin (Mitsubishi BR116);

[0106] Additives: 0.3% oleic acid, 2.5% polyamide wax;

[0107] Silicone oil: Polydimethylsiloxane (viscosity 100 mPa·s) 0.8%;

[0108] Solvents: 6.9% ethylene glycol butyl ether benzoate, 5.5% diethylene glycol butyl ether acetate, and 3.5% dodecyl alcohol ester.

[0109] Preparation method of Galvorn-nickel-silver ternary composite powder:

[0110] Galvorn powder with a particle size of 3-5 μm was purified by dilute hydrochloric acid, nickel powder with a particle size of 1-3 μm was passivated by benzotriazole, and silver powder with a particle size of 0.5-2 μm was modified by stearic acid.

[0111] Weigh each pretreated material according to the mass ratio of Galvorn, nickel, and silver of 2:5:3, and dissolve it in anhydrous ethanol (with 0.4%-0.6% PVP added) at a solid-liquid ratio of 1:9.

[0112] Sonicated at 50kHz for 30 minutes, then at 90kHz for 30 minutes (with intermittent stirring at a constant temperature of 30-40℃).

[0113] The product is dried under vacuum at -0.07 to -0.09 MPa and 65-85℃ for 7-11 hours, then heat-treated at 320℃ in an inert atmosphere for 1 hour, and finally pulverized through a 200-mesh sieve to obtain Galvorn-nickel-silver ternary composite powder.

[0114] The preparation method of the slurry is the same as in Example 1.

[0115] Example 5

[0116] A seed layer slurry for TOPCon batteries, comprising the following components:

[0117] Nano silver powder (D50 250-450nm): 3%;

[0118] Micron-sized silver powder (D50 1.1-2.0μm): 47%;

[0119] Carbon-based ternary composite powder (D50 is 4-5μm): 20%; specifically, it is Galvorn-silver-zirconium boride, and the mass ratio of Galvorn, silver and zirconium boride is 2:6:2;

[0120] Glass powder: 5.5%; by molar percentage, the specific components include: 40% TeO2, 30% PbO2, 12.5% ​​Bi2O3, 0.5% SiO2, 5% WO3, 5% ZnO, 5% Na2CO3, 2% Li2CO3;

[0121] Organic resins: 1.5% ethyl cellulose (Dow STD-100), 1.5% polyvinyl butyral resin (Kuraray B30H), and 2% acrylic resin (Mitsubishi BR116);

[0122] Additives: 0.3% oleic acid, 2.5% polyamide wax;

[0123] Silicone oil: Polydimethylsiloxane (viscosity 100 mPa·s) 0.8%;

[0124] Solvents: 6.9% ethylene glycol butyl ether benzoate, 5.5% diethylene glycol butyl ether acetate, and 3.5% dodecyl alcohol ester.

[0125] Preparation method of Galvorn-silver-zirconium boride ternary composite powder:

[0126] Pretreatment: Remove impurities from 3-5μm Galvorn powder, modify with 0.5-2μm silver powder, and modify with 1-3μm zirconium boride powder KH560;

[0127] Weigh the pretreated materials according to the mass ratio of Galvorn, silver and zirconium boride of 2:6:2, and put them into the ball mill jar with zirconium oxide balls at a ball-to-material ratio of 10:1. Add anhydrous ethanol (solid-liquid ratio 1:5) and 0.3%-0.5% PVP.

[0128] The ternary composite powder of Galvorn-silver-zirconium boride was obtained by ball milling at 200-300 rpm for 4-6 hours at -10~5℃, vacuum drying at 60-70℃ for 6-8 hours, sintering at 550-600℃ for 2 hours under argon atmosphere, and cooling and passing through a 200-mesh sieve.

[0129] The preparation method of the slurry is the same as in Example 1.

[0130] Example 6

[0131] A seed layer slurry for TOPCon batteries, comprising the following components:

[0132] Nano silver powder (D50 250-450nm): 3%;

[0133] Micron-sized silver powder (D50 1.1-2.0μm): 57%;

[0134] Carbon-based ternary composite powder (D50 is 4-5μm): 10%; specifically, it is a ternary composite powder of Galvorn-copper-silicon oxide, with a mass ratio of Galvorn, copper and silicon oxide of 5:3:2.

[0135] Glass powder: 5.5%; by molar percentage, the specific components include: 40% TeO2, 30% PbO2, 12.5% ​​Bi2O3, 0.5% SiO2, 5% WO3, 5% ZnO, 5% Na2CO3, 2% Li2CO3;

[0136] Organic resins: 1.5% ethyl cellulose (Dow STD-100), 1.5% polyvinyl butyral resin (Kuraray B30H), and 2% acrylic resin (Mitsubishi BR116);

[0137] Additives: 0.3% oleic acid, 2.5% polyamide wax;

[0138] Silicone oil: Polydimethylsiloxane (viscosity 100 mPa·s) 0.8%;

[0139] Solvents: 6.9% ethylene glycol butyl ether benzoate, 5.5% diethylene glycol butyl ether acetate, and 3.5% dodecyl alcohol ester.

[0140] Preparation method of Galvorn-copper-silicon oxide ternary composite powder:

[0141] Pretreatment: Galvorn powder with a particle size of 3-5μm is purified by dilute hydrochloric acid, copper powder with a particle size of 1-3μm is passivated by benzotriazole, and silica powder with a particle size of 0.5-2μm is modified by KH550;

[0142] Weigh each pretreated material according to the mass ratio of Galvorn, copper, and silicon dioxide of 5:3:2, and dissolve it in anhydrous ethanol (with 0.3%-0.5% PVP added) at a solid-liquid ratio of 1:8.

[0143] Sonicated at 60kHz for 20 minutes + Sonicated at 80kHz for 40 minutes (with intermittent stirring at a constant temperature of 35-40℃).

[0144] The ternary composite powder of Galvorn-copper-silica is obtained by vacuum drying at -0.08~-0.09MPa and 70-80℃ for 8-10 hours, followed by heat treatment at 300℃ in an inert atmosphere for 1.5 hours, and then pulverizing it through a 200-mesh sieve.

[0145] The preparation method of the slurry is the same as in Example 1.

[0146] Example 7

[0147] A seed layer slurry for TOPCon batteries, comprising the following components:

[0148] Nano silver powder (D50 250-450nm): 3%;

[0149] Micron-sized silver powder (D50 1.1-2.0μm): 57%;

[0150] Carbon-based ternary composite powder (D50 is 4-5μm): 10%; specifically, it is a ternary composite powder of Galvorn-copper-silicon oxide, with a mass ratio of Galvorn, copper and silicon oxide of 2:6:2;

[0151] Glass powder: 5.5%; by molar percentage, the specific components include: 40% TeO2, 30% PbO2, 12.5% ​​Bi2O3, 0.5% SiO2, 5% WO3, 5% ZnO, 5% Na2CO3, 2% Li2CO3;

[0152] Organic resins: 1.5% ethyl cellulose (Dow STD-100), 1.5% polyvinyl butyral resin (Kuraray B30H), and 2% acrylic resin (Mitsubishi BR116);

[0153] Additives: 0.3% oleic acid, 2.5% polyamide wax;

[0154] Silicone oil: Polydimethylsiloxane (viscosity 100 mPa·s) 0.8%;

[0155] Solvents: 6.9% ethylene glycol butyl ether benzoate, 5.5% diethylene glycol butyl ether acetate, and 3.5% dodecyl alcohol ester.

[0156] Preparation method of Galvorn-copper-silicon oxide ternary composite powder:

[0157] Pretreatment: Galvorn powder with a particle size of 3-5μm is purified by dilute hydrochloric acid, copper powder with a particle size of 1-3μm is passivated by benzotriazole, and silica powder with a particle size of 0.5-2μm is modified by KH550;

[0158] Weigh each pretreated material according to the mass ratio of Galvorn, copper, and silicon dioxide of 2:6:2, and dissolve it in anhydrous ethanol (with 0.3%-0.5% PVP added) at a solid-liquid ratio of 1:8.

[0159] Sonicated at 60kHz for 20 minutes + Sonicated at 80kHz for 40 minutes (with intermittent stirring at a constant temperature of 35-40℃).

[0160] The ternary composite powder of Galvorn-copper-silica is obtained by vacuum drying at -0.08~-0.09MPa and 70-80℃ for 8-10 hours, followed by heat treatment at 300℃ in an inert atmosphere for 1.5 hours, and then pulverizing it through a 200-mesh sieve.

[0161] The preparation method of the slurry is the same as in Example 1.

[0162] Example 8

[0163] A seed layer slurry for TOPCon batteries, comprising the following components:

[0164] Nano silver powder (D50 250-450nm): 3%;

[0165] Micron-sized silver powder (D50 1.1-2.0μm): 57%;

[0166] Carbon-based ternary composite powder (D50 is 4-5μm): 10%; specifically, it is a ternary composite powder of Galvorn-copper-silicon oxide, with a mass ratio of Galvorn, copper and silicon oxide of 3:3:4.

[0167] Glass powder: 5.5%; by molar percentage, the specific components include: 40% TeO2, 30% PbO2, 12.5% ​​Bi2O3, 0.5% SiO2, 5% WO3, 5% ZnO, 5% Na2CO3, 2% Li2CO3;

[0168] Organic resins: 1.5% ethyl cellulose (Dow STD-100), 1.5% polyvinyl butyral resin (Kuraray B30H), and 2% acrylic resin (Mitsubishi BR116);

[0169] Additives: 0.3% oleic acid, 2.5% polyamide wax;

[0170] Silicone oil: Polydimethylsiloxane (viscosity 100 mPa·s) 0.8%;

[0171] Solvents: 6.9% ethylene glycol butyl ether benzoate, 5.5% diethylene glycol butyl ether acetate, and 3.5% dodecyl alcohol ester.

[0172] Preparation method of Galvorn-copper-silicon oxide ternary composite powder:

[0173] Pretreatment: Galvorn powder with a particle size of 3-5μm is purified by dilute hydrochloric acid, copper powder with a particle size of 1-3μm is passivated by benzotriazole, and silica powder with a particle size of 0.5-2μm is modified by KH550;

[0174] Weigh each pretreated material according to the mass ratio of Galvorn, copper, and silicon dioxide of 3:3:4, and dissolve them in anhydrous ethanol (with 0.3%-0.5% PVP added) at a solid-liquid ratio of 1:8.

[0175] Sonicated at 60kHz for 20 minutes + Sonicated at 80kHz for 40 minutes (with intermittent stirring at a constant temperature of 35-40℃).

[0176] The ternary composite powder of Galvorn-copper-silica is obtained by vacuum drying at -0.08~-0.09MPa and 70-80℃ for 8-10 hours, followed by heat treatment at 300℃ in an inert atmosphere for 1.5 hours, and then pulverizing it through a 200-mesh sieve.

[0177] The preparation method of the slurry is the same as in Example 1.

[0178] Comparative Example 1

[0179] A seed layer slurry for TOPCon batteries is made from the following raw materials in parts by weight:

[0180] Nano silver powder (D50 250-450nm): 3%;

[0181] Micron-sized silver powder (D50 1.1-2.0μm): 67%;

[0182] Glass powder: 5.5%; by molar percentage, the specific components include: 40% TeO2, 30% PbO2, 12.5% ​​Bi2O3, 0.5% SiO2, 5% WO3, 5% ZnO, 5% Na2CO3, 2% Li2CO3;

[0183] Organic resins: 1.5% ethyl cellulose (Dow STD-100), 1.5% polyvinyl butyral resin (Kuraray B30H), and 2% acrylic resin (Mitsubishi BR116);

[0184] Additives: 0.3% oleic acid, 2.5% polyamide wax;

[0185] Silicone oil: Polydimethylsiloxane (viscosity 100 mPa·s) 0.8%;

[0186] Solvents: 6.9% ethylene glycol butyl ether benzoate, 5.5% diethylene glycol butyl ether acetate, and 3.5% dodecyl alcohol ester.

[0187] The preparation method of the slurry is the same as in Example 1.

[0188] Comparative Example 2

[0189] A seed layer slurry for TOPCon batteries, comprising the following components:

[0190] Nano silver powder (D50 250-450nm): 3%;

[0191] Micron-sized silver powder (D50 1.1-2.0μm): 32%;

[0192] Carbon-based ternary composite powder (D50 is 4-5μm): 35%; specifically, it is a ternary composite powder of Galvorn-copper-silicon oxide, with a mass ratio of Galvorn, copper and silicon oxide of 3:5:2.

[0193] Glass powder: 5.5%; by molar percentage, the specific components include: 40% TeO2, 30% PbO2, 12.5% ​​Bi2O3, 0.5% SiO2, 5% WO3, 5% ZnO, 5% Na2CO3, 2% Li2CO3;

[0194] Organic resins: 1.5% ethyl cellulose (Dow STD-100), 1.5% polyvinyl butyral resin (Kuraray B30H), and 2% acrylic resin (Mitsubishi BR116);

[0195] Additives: 0.3% oleic acid, 2.5% polyamide wax;

[0196] Silicone oil: Polydimethylsiloxane (viscosity 100 mPa·s) 0.8%;

[0197] Solvents: 6.9% ethylene glycol butyl ether benzoate, 5.5% diethylene glycol butyl ether acetate, and 3.5% dodecyl alcohol ester.

[0198] The preparation method of Galvorn-copper-silica ternary composite powder and slurry is the same as in Example 1.

[0199] Using the Galvorn-based ternary composite conductive pastes from Examples 1-8 and Comparative Example 2 as samples, each sample was printed on the same substrate for relevant property tests. The test process is as follows:

[0200] 1. Contact resistance: After printing specific patterns onto TOPcon solar cells using composite conductive paste, the paste is dried and cured; solar cells of a specified size with printed patterns are cut out using a laser slicing machine; and contact resistance is measured using a contact resistance device.

[0201] 2. Resistivity test: The resistance between the two ends of the electrodes is tested using a four-probe ohmmeter.

[0202] 3. Printability Test: The conductive pastes from the above embodiments and comparative examples were printed onto the back of the silicon wafer using screen printing technology. The screen specifications used for printability testing were a knotless, multi-aperture screen with 600 mesh / 5μm wire diameter / total thickness of 12-13μm / apertures of 10μm, 9μm, and 8μm respectively. The solar cells were dried in an infrared drying oven, and then the printability of the paste was observed with the naked eye and an optical microscope to determine whether there were any broken grids or incomplete prints.

[0203] The test results of the examples and comparative examples are shown in Table 1.

[0204] Table 1 Test results of the examples and comparative examples

[0205]

[0206] As can be seen from Table 1:

[0207] (1) A comparison of the data from Examples 1-3 and Comparative Example 1 shows that introducing Galvorn-copper-silicon oxide ternary composite powder (3:5:2) to partially replace silver powder can effectively reduce the cost of the paste. When the replacement ratio is 10%, the photoelectric conversion efficiency of the prepared paste is only 0.03% different from that of the pure silver paste in Comparative Example 1, indicating that at this ratio, Galvorn and copper in the composite powder can synergistically form an effective supplementary conductive path without destroying the integrity of the original silver conductive network. As the replacement ratio increases to 20% or even 30%, the silver content decreases and copper slightly agglomerates, but the paste still maintains excellent performance (efficiency > 26.69%), and the cost reduction effect is more significant, confirming the effectiveness of the composite powder in a wide range of addition ratios. This invention achieves a balance between "conductive network integrity" and "synergistic effect of auxiliary conductive phase" by controlling the substitution ratio of Galvorn-copper-silicon oxide ternary composite powder. A substitution ratio of 10% achieves the best balance between cost reduction and maintaining ultimate performance. It can reduce costs by introducing base metals and carbon nanomaterials, while maintaining the high conductivity of pure silver paste to the greatest extent, thus meeting the performance requirements of silver paste for TOPCon battery seed layer.

[0208] (2) Combining the data from Examples 1-3 and Comparative Example 2, when the proportion of Galvorn-copper-silica ternary composite powder exceeds 30% (e.g., 35% in Comparative Example 2), the photoelectric conversion efficiency decreases, and the printing grid breakage problem occurs. Analysis shows that the decrease in the proportion of silver powder leads to breaks in the conductive network, while the agglomeration of copper powder and the increase in the proportion of silica insulating phase cause a slight loss in electrical performance, and grid breakage occurs due to screen blockage during printing. Therefore, to ensure the overall performance of the paste, the addition amount of Galvorn-based ternary composite powder is preferably no more than 30%.

[0209] (3) At the same addition amount (20%), comparing Examples 2, 4, and 5 reveals that composite powders composed of different functional phases affect the performance of the slurry. The Galvorn-copper-silica (Example 2) ternary composite powder exhibits the best conductivity; this is due to the fact that copper has a conductivity close to that of silver, synergistically completing the conductive pathway with Galvorn, while silica effectively inhibits particle agglomeration, resulting in a continuous conductive network with low interfacial loss, and conductivity closest to that of pure silver paste. The Galvorn-nickel-silver ternary composite powder (Example 4) is the second best; nickel improves the stability of the system, but its intrinsic conductivity is only 24% of that of copper, slightly increasing electron transport resistance, and its conductivity is slightly inferior to that of the copper-based system. The Galvorn-silver-zirconium boride ternary composite powder (Example 5) is the worst; silver ensures low basic resistance, but zirconium boride is an insulating phase, and its proportion increases at a 20% addition amount, slightly hindering electron transport across particles, resulting in slightly weaker conductivity. This comparison shows that selecting a metal phase with excellent conductivity (such as copper) and combining it with an appropriate ceramic phase (such as silica) is crucial for constructing an efficient composite conductive network.

[0210] (4) Comparing the data from Example 1 with those from Examples 6-8, the mass ratio of Galvorn, copper, and silica has a decisive influence on the performance of the composite powder and the final slurry. When the ratio of Galvorn powder, copper powder, and silica powder in this invention is 3:5:2, the slurry exhibits excellent and balanced performance. Any deviation from the ratio of any component may lead to a decrease in performance.

[0211] ① Excessive Galvorn powder (Example 6, ratio 5:3:2) will significantly increase the risk of agglomeration in the system, making it prone to grid breakage, forming conductive phase "clumps", and disrupting the continuity of the conductive network; at the same time, insufficient copper powder will weaken the synergistic conductive effect of highly conductive base metals, resulting in a decrease in the overall conductivity of the composite powder.

[0212] ② If the proportion of copper powder is too high (Example 7, ratio 2:6:2), the passivation film on its surface is prone to cracking, the risk of oxidation is aggravated in the high-temperature process, and the formed copper oxide will hinder electron transport; moreover, excessive copper powder is prone to particle agglomeration, which reduces the compatibility with Galvorn and silicon oxide, and local "breakpoints" appear in the conductive network, resulting in a significant increase in contact resistance. At the same time, structural defects such as cracking and detachment are prone to occur after the slurry is sintered.

[0213] ③ Excessive silicon oxide ratio (Example 8, ratio 3:3:4): As an insulating phase, excessive addition of silicon oxide will increase the proportion of insulating components in the system, severely hindering electron transport across particles and causing a significant deterioration in the conductivity of the composite powder. At the same time, too much silicon oxide will reduce the compatibility of the composite powder with other components of the silver paste, reduce the density of the paste film after printing, and affect the mechanical stability of the electrode.

[0214] Therefore, the 3:5:2 mass ratio has been proven to be the optimal ratio for leveraging the lightweight conductivity of Galvorn, the high conductivity of copper, and the interface modification and agglomeration inhibition effects of silicon oxide, making it the core ratio for achieving cost reduction and efficiency improvement.

[0215] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A seed layer slurry for TOPCon batteries, characterized in that, The seed layer slurry comprises, by weight percentage: 0.5-5 wt% nano silver powder, 35-70 wt% micron silver powder, 5-30 wt% carbon-based ternary composite powder, and 4 wt% glass powder. 6.5 wt%, organic resin 3-9 wt%, organic solvent 1-20 wt%, silicone oil 0.1-2 wt%, additives 0.1-1 wt%; wherein, the carbon-based ternary composite powder comprises a base phase and a functional phase, the functional phase being combined with the base phase by coating and / or embedding to form an integrated composite structure; the base phase is a carbon nanocomposite material, and the functional phase comprises at least two of base metals, oxides, and borides; The carbon nanocomposite material is composed of multiple carbon nanotubes as basic units, with each carbon nanotube having a diameter of 10-50 nm and a length of 3-5 μm.

2. The seed layer slurry for TOPCon batteries as described in claim 1, characterized in that, The carbon nanotubes are connected by van der Waals forces and some in-situ carbon-carbon covalent bonds to form a dense structure. The density of the carbon nanocomposite material is ≤2.0 g / cm³ and the porosity is ≤2%.

3. The seed layer slurry for TOPCon batteries as described in claim 1, characterized in that, The base metal includes at least one of copper, tungsten, tin, nickel, and aluminum; and / or the oxide includes at least one of silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, and boron oxide; and / or the boride includes at least one of titanium boride, tungsten boride, and zirconium boride.

4. The seed layer slurry for TOPCon batteries as described in claim 1, characterized in that, The carbon-based ternary composite powder includes one or more of the following: carbon-nickel-silver ternary composite powder, carbon-copper-silicon oxide ternary composite powder, and carbon-silver-zirconium boride ternary composite powder.

5. The seed layer slurry for TOPCon batteries as described in claim 4, characterized in that, In the carbon-copper-silicon oxide ternary composite powder, the mass ratio of carbon nanocomposite material, copper and silicon oxide is 3:5:

2.

6. The seed layer slurry for TOPCon batteries as described in claim 1, characterized in that, The silver nanoparticles are single-peak spherical silver powders with a D50 of 220-550 nm and a tap density of 5.5-8.8 g / cm³. 3 Its specific surface area is 1.0-1.95 m². 2 / g; the micron-sized silver powder is a single-peak spherical silver powder with a D50 of 1.2-1.8μm and a tap density of 4.5-7.5g / cm³. 3 Its specific surface area is 0.25-0.85 m². 2 / g.

7. The seed layer slurry for TOPCon batteries as described in claim 1, characterized in that, The preparation method of the carbon-based ternary composite powder includes at least one of the following: ultrasonic dispersion-vacuum drying method, low-temperature ball milling-inert sintering method, gas atomization-in-situ growth method, and chemical plating coating method.

8. The seed layer slurry for TOPCon batteries as described in claim 7, characterized in that, The ultrasonic dispersion-vacuum drying method includes the following steps: Pre-treat the base phase and functional phase, remove impurities from the base phase and passivate and / or modify the functional phase; Weigh the pretreated base phase and functional phase according to the ratio, add them to the dispersion, and mix to obtain a mixed slurry with a solid content of 30%-50%. The above-mentioned mixed slurry was ultrasonically dispersed at 50-90 kHz and 200-600 W for 50-70 min, and then centrifuged to remove impurities and concentrate until the solid content was 60%-70%. The concentrated mixed slurry was vacuum dried at 60-100℃ for 7-11 hours to obtain a dried mixed powder. Under an inert atmosphere, the dried mixed powder is heat-treated at 300-320℃ for 1-2 hours, cooled, pulverized and sieved to obtain the desired carbon-based ternary composite powder.

9. The seed layer slurry for TOPCon batteries as described in claim 7, characterized in that, The low-temperature ball milling-inert sintering method includes the following steps: The basic phase and functional phase are pretreated by removing impurities from the surface of the basic phase and passivating and / or modifying the surface of the functional phase. Weigh the pretreated base phase and functional phase according to the ratio and add them to the dispersion. Control the material temperature ≤50℃ during ball milling. After ball milling for 3-6 hours, vacuum dry at 60-70℃ for 5-8 hours to obtain ball-milled dried mixed powder. Under an inert atmosphere, the ball-milled and dried mixed powder is sintered at 500-800℃ for 1-2 hours, cooled, pulverized and sieved to obtain the desired carbon-based ternary composite powder.

10. A method for preparing a seed layer slurry for TOPCon batteries as described in any one of claims 1-9, characterized in that, Includes the following steps: After weighing the nano silver powder, micron silver powder, carbon-based ternary composite powder, glass powder, organic resin, organic solvent, silicone oil, and additives according to the specified ratio, add them to the reaction apparatus and mix and stir evenly. Then, the mixture is ground using a three-roll mill with a grinding interval of 10-120μm and a grinding speed of 50-400r / min to obtain a seed layer slurry with a fineness of ≤5μm.

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