A copper-based conductive electrode paste, a preparation method thereof, a back contact solar cell and a solar cell module

Abstract

The application provides a copper-based conductive electrode paste, a preparation method thereof, a back contact solar cell and a solar cell module. The copper-based conductive electrode paste comprises copper powder, glass powder, an organic carrier, an organic corrosion inhibitor and alkaline oxide powder; the organic corrosion inhibitor comprises benzotriazole. The alkaline oxide powder and the organic corrosion inhibitor are simultaneously introduced into the copper-based conductive electrode paste, so that the copper electrode is cooperatively protected; the alkaline oxide powder can be neutralized with acetic acid generated by decomposition of a film during an aging process as an inorganic neutralizing agent; the organic corrosion inhibitor forms a dense, stable and insoluble polymer protective film on the surface of the copper powder through a lone pair of electrons in the molecule, efficiently inhibits corrosion of the copper and avoids damage of the copper electrode; the two are cooperatively matched, so that the acid corrosion resistance and long-term reliability of the copper electrode are improved, and the risk of performance degradation or even failure of the module caused by corrosion of the copper electrode is avoided.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically relating to a copper-based conductive electrode paste and its preparation method, a back-contact solar cell, and a solar cell module. Background Technology

[0002] Against the backdrop of the photovoltaic industry's continuous pursuit of "cost reduction and efficiency improvement," cost control of conductive electrode paste has become a key issue. Currently, the industry is actively exploring solutions to replace the precious metal silver with the cheaper base metal copper. The volumetric conductivity of bulk pure copper (approximately 5.96 × 10⁻⁶) 7 S / m) and silver (approximately 6.30 × 10 7 The S / m ratio is relatively close. Theoretically, if a copper electrode with high density, low oxidation and good ohmic contact with the silicon substrate can be prepared, its conductivity can be close to that of a silver electrode, thereby significantly reducing the cost.

[0003] However, copper faces serious challenges in practical module applications: copper electrodes are extremely prone to reacting with acetic acid produced by the decomposition of encapsulating films (such as EVA) during the aging process. This reaction can lead to a series of problems such as electrode corrosion, decreased conductivity, weakened adhesion, and discoloration, ultimately causing module performance degradation or even failure.

[0004] Therefore, how to avoid performance degradation or even failure of the component due to the reaction between the copper electrode and the acidic substances released from the decomposition of the encapsulating film is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a copper-based conductive electrode paste and its preparation method, a back-contact solar cell, and a solar cell module. This invention simultaneously introduces alkaline oxide powder and an organic corrosion inhibitor into the copper-based conductive electrode paste, achieving synergistic protection of the copper electrode. The alkaline oxide powder, acting as an inorganic neutralizing agent, can neutralize the acetic acid produced during the decomposition of the adhesive film during aging, thus playing a role in "chemical repair." Meanwhile, the organic corrosion inhibitor, through its lone pairs of electrons, forms a dense, stable, and insoluble polymer protective film on the copper powder surface. This film effectively inhibits copper corrosion by acting as a barrier and altering the electrochemical interface properties, preventing damage to the copper electrode. The synergistic effect of these two agents constructs an effective physical and chemical protective barrier, significantly improving the acid corrosion resistance and long-term reliability of the copper electrode, thereby fundamentally avoiding the risk of module performance degradation or even failure due to copper electrode corrosion.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a copper-based conductive electrode paste, the copper-based conductive electrode paste comprising copper powder, glass powder, organic carrier, organic corrosion inhibitor and alkaline oxide powder; wherein the organic corrosion inhibitor comprises benzotriazole.

[0008] This invention simultaneously introduces alkaline oxide powder and organic corrosion inhibitor into a copper-based conductive electrode slurry, achieving synergistic protection for the copper electrode. The alkaline oxide powder, acting as an inorganic neutralizing agent, can neutralize the acetic acid produced during the decomposition of the slurry film during aging, thus playing a role in "chemical repair." Meanwhile, the organic corrosion inhibitor, through its lone pairs of electrons, forms a dense, stable, and insoluble polymer protective film on the copper powder surface. This film effectively inhibits copper corrosion by acting as a barrier and altering the electrochemical interface properties, preventing damage to the copper electrode. The synergistic effect of these two agents constructs an effective physical and chemical protective barrier, significantly improving the acid corrosion resistance and long-term reliability of the copper electrode, thereby fundamentally avoiding the risk of component performance degradation or even failure due to copper electrode corrosion.

[0009] Preferably, the copper-based conductive electrode paste comprises, by weight, the following:

[0010] The mixture contains 85-90 parts copper powder, 2-4 parts glass powder, 4-8 parts organic carrier, 1-3 parts organic corrosion inhibitor, and 1-3 parts alkaline oxide powder. For example, the copper powder can be 85, 86, 87, 88, 89, or 90 parts, the glass powder can be 2, 3, or 4 parts, the organic carrier can be 4, 5, 6, 7, or 8 parts, the organic corrosion inhibitor can be 1, 2, or 3 parts, and the alkaline oxide powder can be 1, 2, or 3 parts.

[0011] This invention introduces a specific amount of alkaline oxide powder into a copper-based conductive electrode paste. This design utilizes the interfacial neutralization reaction between the alkaline oxide powder and hydrolysis byproducts of the encapsulation material (such as acetic acid) to construct a local chemical barrier at the copper electrode interface, thereby delaying the electrochemical corrosion process.

[0012] This invention introduces a specific proportion of organic corrosion inhibitor into a copper-based conductive electrode slurry. The corrosion inhibitor molecules form a dense monomolecular protective film on the surface of copper powder through physical or chemical adsorption. This film can effectively block the direct contact between copper and corrosive media such as moisture, oxygen, and acidic ions. At the same time, it can increase the corrosion potential of the copper electrode or inhibit the anodic / cathode electrochemical reaction, thereby significantly delaying the corrosion process of copper and ensuring the long-term conductive stability of the electrode.

[0013] Preferably, the alkaline oxide powder includes magnesium oxide powder.

[0014] Preferably, the copper powder comprises spherical copper powder.

[0015] The reason for choosing spherical copper powder in this invention is that, due to its geometric symmetry, spherical copper powder can achieve the densest packing during the slurry coating and drying process, with the smallest porosity between particles. After subsequent sintering, the spherical particles melt and diffuse at the contact point, thereby forming a dense conductive film layer with low porosity and good continuity in situ.

[0016] Preferably, the glass powder includes Pb-Si-B based glass powder.

[0017] Preferably, the organic carrier comprises a resin and a solvent.

[0018] Preferably, the Pb-Si-B glass powder comprises, by weight percentage:

[0019] The composition consists of 40-60% Pb3O4, 15-25% SiO2, 15-20% B2O3, and 5-15% ZnO. For example, Pb3O4 can be 40%, 50%, or 60%, SiO2 can be 15%, 20%, or 25%, B2O3 can be 15%, 16%, 17%, 18%, 19%, or 20%, and ZnO can be 5%, 10%, or 15%.

[0020] This invention uses the components in the above proportions to construct Pb-Si-B glass powder, making the Pb-Si-B glass powder a low-melting-point glass powder. During the sintering process, the low-melting-point glass powder melts to form a liquid phase, which can wet and encapsulate copper powder particles, fill pores, and promote particle rearrangement and densification. After cooling, it forms a solid glass phase, which bonds the copper particles together and forms a strong mechanical and chemical bond with the substrate. This is the key to achieving low-temperature densification sintering and reliable connection.

[0021] Preferably, the resin comprises ethyl cellulose and / or acrylic resin.

[0022] Preferably, the solvent includes any one or a combination of at least two of butyl carbitol acetate, dodecayl alcohol ester, or butyl carbitol.

[0023] Preferably, in the organic carrier, the mass ratio of resin to solvent is (5-15):(85-95), wherein the resin selection range "5-15" can be, for example, 5, 10 or 15, and the solvent selection range "85-95" can be, for example, 85, 90 or 95.

[0024] Preferably, the copper-based conductive electrode paste further includes additives, which include dispersants and / or thixotropic agents, preferably a combination of dispersants and thixotropic agents. For example, the mass ratio of dispersant to thixotropic agent is 1:1, etc.

[0025] In this invention, the dispersant is used to prevent copper powder from agglomerating, and the thixotropic agent is used to regulate the rheological properties (i.e., fluidity) of the copper paste, so that it has ideal processability in each stage of storage, printing and sintering.

[0026] Preferably, based on the total mass of the copper powder, glass powder, organic carrier, organic corrosion inhibitor, and alkaline oxide powder, the mass percentage of the additive is 2-4%, for example, it can be 2%, 3%, or 4%.

[0027] Preferably, the dispersant comprises TDO (aliphatic diamine organic salt) and / or sodium tripolyphosphate.

[0028] Preferably, the thixotropic agent comprises polyamide wax and / or fumed silica.

[0029] Preferably, the viscosity of the copper-based conductive electrode paste is 2000-3000 cP, for example, it can be 2000 cP, 2200 cP, 2400 cP, 2600 cP, 2800 cP or 3000 cP, etc.

[0030] In a second aspect, the present invention provides a method for preparing a copper-based conductive electrode paste as described in the first aspect, the method comprising the following steps:

[0031] Copper powder, glass powder, and alkaline oxide powder are first mixed to obtain a mixed powder.

[0032] The mixed powder, organic corrosion inhibitor and organic carrier are mixed a second time to obtain the copper-based conductive electrode slurry.

[0033] The organic corrosion inhibitor includes benzotriazole.

[0034] This invention premixes inorganic powders (copper powder, glass powder, and alkaline oxide powder) to ensure uniform distribution of alkaline oxides within the copper powder particles, laying the foundation for subsequent neutralization of acidic corrosion. Subsequently, an organic corrosion inhibitor and carrier are introduced, allowing the inhibitor molecules to be fully adsorbed on the pre-dispersed, clean copper powder surface, forming a complete and dense protective film, thus maximizing functionality. This process not only enhances the synergistic protective effect of each component but also effectively optimizes the dispersion stability of the slurry and its adaptability to printing processes. Ultimately, the resulting copper electrode exhibits significantly improved corrosion resistance, electrical reliability, and long-term stability at the component end.

[0035] Preferably, during the first mixing process, the stirring speed is 80-100 rpm, for example, 80 rpm, 90 rpm or 100 rpm, and the dispersion speed is 800-1200 rpm, for example, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm or 1200 rpm.

[0036] It should be noted that the stirring speed mainly achieves macroscopic mixing, which is to enable the different components in the slurry to achieve preliminary and overall uniform mixing, and promote the heat and mass transfer process in the system (mainly referring to the solid-liquid mixing between organic and inorganic components); while the dispersion speed focuses on microscopic mixing, aiming to break up particle agglomerates through shear force, so that inorganic components such as copper powder, glass powder and alkaline oxides are uniformly and stably dispersed in the system at their original particle size.

[0037] Preferably, the second mixing includes a first centrifugal dispersion, a grinding dispersion, and a second centrifugal dispersion performed sequentially.

[0038] This invention achieves uniform and stable slurry dispersion through the synergistic combination of first centrifugal dispersion, grinding dispersion, and second centrifugal dispersion. The first centrifugal dispersion utilizes the powerful convection and shear forces generated by the centrifugal force field to rapidly and initially impregnate and disperse powders (such as copper powder and glass powder) into a carrier, forming a macroscopically uniform slurry matrix. Grinding dispersion applies extremely strong local mechanical forces to the slurry through the collision, friction, and shearing of grinding media (such as zirconium beads), thoroughly breaking down hard and soft agglomerates of the powder, bringing them to or near their original particle size, and achieving uniform distribution at the microscale. The second centrifugal dispersion eliminates stress in the ground slurry, stabilizing its rheological state, while simultaneously using centrifugal force to remove air bubbles entrained during grinding and separating and removing any trace amounts of large particles or impurities. Preferably, additives, including dispersants and / or thixotropic agents, are added during the second mixing process.

[0039] Preferably, the preparation method includes the following steps:

[0040] (1) Provide Pb-Si-B glass powder with a particle size D50 of 0.6-1 μm (e.g., 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm, etc.), the preparation steps include:

[0041] Pb3O4, SiO2, B2O3, and ZnO are mixed at a centrifugal speed of 600-1000 rpm (e.g., 600 rpm, 700 rpm, 800 rpm, 900 rpm, or 1000 rpm, etc.), and then calcined at 800-1000℃ (e.g., 800℃, 900℃, or 1000℃, etc.) for 40-80 min (e.g., 40 min, 60 min, or 80 min, etc.) to obtain liquid glass; water quenching is then performed to transform the liquid glass into solid glass, followed by ball milling and sand milling to obtain the Pb-Si-B glass powder.

[0042] An organic carrier is provided, and the preparation steps include:

[0043] Ethyl cellulose, acrylic resin, butyl carbitol acetate, dodecayl alcohol ester and butyl carbitol are mixed at a stirring speed of 400-800 rpm (e.g., 400 rpm, 600 rpm or 800 rpm) and a temperature of 70-80°C (e.g., 70°C, 75°C or 80°C) for 3-5 hours (e.g., 3 hours, 4 hours or 5 hours) to obtain a uniformly mixed organic carrier.

[0044] (2) The Pb-Si-B glass powder, spherical copper powder with a particle size D50 of 0.8-1.2μm (e.g., 0.8μm, 0.9μm, 1μm, 1.1μm or 1.2μm) and magnesium oxide powder with a particle size D50 of 1-1.2μm (e.g., 1μm, 1.1μm or 1.2μm) are first mixed, wherein the stirring speed is 80-100rpm and the dispersion speed is 800-1200rpm to obtain a mixed powder.

[0045] (3) The mixed powder, additives, organic corrosion inhibitors and organic carriers are subjected to a first centrifugal dispersion at a speed of 4000-6000 rpm (e.g., 4000 rpm, 5000 rpm or 6000 rpm, etc.) to obtain a solid-liquid mixed phase; wherein the organic corrosion inhibitor includes benzotriazole and the additives include dispersants and / or thixotropic agents.

[0046] The solid-liquid mixture is ground and dispersed using a three-roll mill to obtain a ground slurry. In the three-roll mill, the rotational speed ratio of the front roller, middle roller, and rear roller is (2-4):(5-7):(3-5) (wherein, the selection range of the front roller "2-4" can be, for example, 2, 3, or 4, the selection range of the middle roller "5-7" can be, for example, 5, 6, or 7, and the selection range of the rear roller "3-5" can be, for example, 3, 4, or 5), and the rotational speed of the middle roller is 400-600 rpm (for example, 400 rpm, 500 rpm, or 600 rpm).

[0047] The ground slurry is then subjected to a second centrifugal dispersion at a speed of 5000-7000 rpm (e.g., 5000 rpm, 6000 rpm, or 7000 rpm) to obtain a copper-based conductive electrode slurry.

[0048] Thirdly, the present invention provides a back-contact solar cell, wherein the copper electrode in the back-contact solar cell is prepared using the copper-based conductive electrode paste as described in the first aspect.

[0049] For example, the copper electrode is prepared by screen printing a copper-based conductive electrode paste onto the fine grid of the back contact solar cell, and then sintering it in a sintering furnace to obtain the copper electrode.

[0050] Fourthly, the present invention provides a solar cell module, which is prepared using at least one back-contact solar cell as described in the third aspect.

[0051] For example, the fabrication of a solar cell module can be carried out using the following steps:

[0052] (1) String welding of solar cells:

[0053] The back-contact solar cell is diced using a non-destructive laser dicing machine to obtain half-cells; then, a dicing and welding machine is used to weld the welding strip to the half-cells, and the entire series is connected in series, welding nine half-cells.

[0054] (2) Layering:

[0055] After the battery cells are wired together, the battery strings are laid out onto the front adhesive film by a layout machine, and then conveyed to the stacking welding machine for welding of the middle busbar and the two end busbars. The middle busbar divides the battery array into two parts. The upper half of the six battery strings are connected in series, and the lower half of the six battery strings are also connected in series. The upper and lower parts are connected in parallel.

[0056] (3) Second-stage laying:

[0057] After the stacking is completed, a second layer of laying is carried out, in which the high-temperature cloth, the encapsulation back plate, the back encapsulation film, and the solar cells are laid in sequence.

[0058] (4) Lamination:

[0059] Lamination is performed using a three-cavity double-layer laminate.

[0060] (5) Junction box installation:

[0061] After lamination, the components are transferred to the junction box installation station. Glue is applied to the bottom of the junction box, the lead wires are soldered, the junction box is filled with glue, and after filling with glue, it is transferred to the curing chamber for curing. After curing is completed, the junction box cover is installed.

[0062] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] This invention simultaneously introduces alkaline oxide powder and organic corrosion inhibitor into a copper-based conductive electrode slurry, achieving synergistic protection for the copper electrode. The alkaline oxide powder, acting as an inorganic neutralizing agent, can neutralize the acetic acid produced during the decomposition of the slurry film during aging, thus playing a role in "chemical repair." Meanwhile, the organic corrosion inhibitor, through its lone pairs of electrons, forms a dense, stable, and insoluble polymer protective film on the copper powder surface. This film effectively inhibits copper corrosion by acting as a barrier and altering the electrochemical interface properties, preventing damage to the copper electrode. The synergistic effect of these two agents constructs an effective physical and chemical protective barrier, significantly improving the acid corrosion resistance and long-term reliability of the copper electrode, thereby fundamentally avoiding the risk of component performance degradation or even failure due to copper electrode corrosion. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of the solar cell module provided in Embodiment 1 of the present invention undergoing TC200 testing.

[0066] Figure 2 This is a schematic diagram of the solar cell module provided in Comparative Example 1 of the present invention undergoing TC200 testing. Detailed Implementation

[0067] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0068] Example 1

[0069] This embodiment provides a copper-based conductive electrode paste, which, by weight, comprises:

[0070] 87 parts of spherical copper powder, 3 parts of Pb-Si-B glass powder, 6 parts of organic carrier, 2 parts of benzotriazole and 2 parts of magnesium oxide powder.

[0071] The Pb-Si-B glass powder comprises, by weight percentage: 50% Pb3O4, 20% SiO2, 20% B2O3, and 10% ZnO. The organic carrier comprises ethyl cellulose, acrylic resin, butyl carbitol acetate, dodecayl alcohol ester, and butyl carbitol in a mass ratio of 8:2:20:30:40.

[0072] The copper-based conductive electrode slurry also contains additives, which include a dispersant and a thixotropic agent in a mass ratio of 1:1. The dispersant is sodium tripolyphosphate and the thixotropic agent is polyamide wax. Based on the total mass of the spherical copper powder, Pb-Si-B glass powder, organic carrier, benzotriazole and magnesium oxide powder, the mass percentage of the additives is 3%.

[0073] The viscosity of the copper-based conductive electrode slurry is 2000 cP.

[0074] This embodiment also provides a method for preparing the copper-based conductive electrode paste as described above, the preparation method comprising the following steps:

[0075] (1) Provide Pb-Si-B glass powder with a particle size D50 of 0.8 μm. The preparation steps include:

[0076] Pb3O4, SiO2, B2O3, and ZnO were mixed in a predetermined ratio at a centrifugal speed of 800 rpm, then placed in a ceramic crucible and placed in a muffle furnace. The mixture was heated to 900°C at a heating rate of 10°C / min and calcined for 60 min to obtain liquid glass. The liquid glass was then quenched in ice water to transform it into solid glass. The liquid glass was then ball-milled, and the ball-milled glass fragments were then sand-milled to obtain the Pb-Si-B glass powder.

[0077] An organic carrier is provided, and the preparation steps include:

[0078] Ethyl cellulose, acrylic resin, butyl carbitol acetate, dodecayl alcohol ester and butyl carbitol were mixed at a predetermined ratio at a stirring speed of 600 rpm and a temperature of 75°C for 4 hours to obtain a uniformly mixed organic carrier.

[0079] (2) The Pb-Si-B glass powder, spherical copper powder with a particle size D50 of 1.0 μm and magnesium oxide powder with a particle size D50 of 1.1 μm are first mixed using a shear mixer, wherein the stirring speed is 90 rpm and the dispersion speed is 1000 rpm, to obtain a mixed powder.

[0080] (3) The mixed powder, dispersant, thixotropic agent, benzotriazole and organic carrier are centrifuged and dispersed for the first time using a high-speed centrifugal disperser at a speed of 5000 rpm and a number of centrifugations of 5 times to obtain a solid-liquid mixed phase.

[0081] The solid-liquid mixture is ground and dispersed using a three-roll mill to obtain a ground slurry; in the three-roll mill, the speed ratio of the front roller, the middle roller and the rear roller is 3:6:4, and the speed of the middle roller is 500 rpm.

[0082] The ground slurry was subjected to a second centrifugal dispersion at a speed of 6000 rpm for 5 times to obtain the copper-based conductive electrode slurry.

[0083] This embodiment also provides an N-type back-contact solar cell, wherein the copper electrode in the N-type back-contact solar cell is prepared using the copper-based conductive electrode paste as described above; the preparation steps of the copper electrode include:

[0084] Copper-based conductive electrode paste is screen-printed onto the fine grid of a back-contact solar cell using a screen printing machine, and then sintered at 750°C using a Despatch sintering furnace to obtain the copper electrode.

[0085] This embodiment also provides a solar cell module, the fabrication steps of which include:

[0086] (a) Stringing of solar cells:

[0087] The N-type back-contact solar cell provided above is diced using a non-destructive laser dicing machine to obtain half-cell cells; then, a dicing and welding machine is used to weld the welding strip to the half-cell cells, and the entire series is connected in series to weld 9 half-cell cells.

[0088] (b) Layering:

[0089] After the battery cells are wired together, the battery strings are laid out onto the front adhesive film by a layout machine, and then conveyed to the stacking welding machine for welding of the middle busbar and the two end busbars. The middle busbar divides the battery array into two parts. The upper half of the six battery strings are connected in series, and the lower half of the six battery strings are also connected in series. The upper and lower parts are connected in parallel.

[0090] (c) Second layer laying:

[0091] After the stacking is completed, a second layer of laying is carried out, in which the high-temperature cloth, the encapsulation back plate, the back encapsulation film, and the solar cells are laid in sequence.

[0092] (d) Lamination:

[0093] Lamination is performed using a three-cavity double-layer laminate.

[0094] (e) Junction box installation:

[0095] After lamination, the components are transferred to the junction box installation station. Glue is applied to the bottom of the junction box, the lead wires are soldered, the junction box is filled with glue, and after filling with glue, it is transferred to the curing chamber for curing. After curing is completed, the junction box cover is installed.

[0096] Example 2

[0097] This embodiment provides a copper-based conductive electrode paste, which, by weight, comprises:

[0098] 85 parts of spherical copper powder, 3 parts of Pb-Si-B glass powder, 6 parts of organic carrier, 3 parts of benzotriazole and 3 parts of magnesium oxide powder.

[0099] The Pb-Si-B glass powder comprises, by weight percentage: 40% Pb3O4, 25% SiO2, 20% B2O3, and 15% ZnO. The organic carrier comprises ethyl cellulose, acrylic resin, butyl carbitol acetate, dodecayl alcohol ester, and butyl carbitol in a mass ratio of 8:2:20:30:40.

[0100] The copper-based conductive electrode slurry also contains additives, which include a dispersant and a thixotropic agent in a mass ratio of 1:1. The dispersant is sodium tripolyphosphate and the thixotropic agent is polyamide wax. Based on the total mass of the spherical copper powder, Pb-Si-B glass powder, organic carrier, benzotriazole and magnesium oxide powder, the mass percentage of the additives is 2%.

[0101] The viscosity of the copper-based conductive electrode slurry is 2000 cP.

[0102] This embodiment also provides a method for preparing the copper-based conductive electrode paste as described above, the preparation method comprising the following steps:

[0103] (1) Provide Pb-Si-B glass powder with a particle size D50 of 0.6 μm. The preparation steps include:

[0104] Pb3O4, SiO2, B2O3, and ZnO were mixed in a predetermined ratio at a centrifugal speed of 600 rpm, then placed in a ceramic crucible and placed in a muffle furnace. The mixture was heated to 800°C at a heating rate of 10°C / min and calcined for 80 min to obtain liquid glass. The liquid glass was then quenched in ice water to transform it into solid glass. The liquid glass was then ball-milled, and the ball-milled glass fragments were then sand-milled to obtain the Pb-Si-B glass powder.

[0105] An organic carrier is provided, and the preparation steps include:

[0106] Ethyl cellulose, acrylic resin, butyl carbitol acetate, dodecayl alcohol ester and butyl carbitol were mixed in a predetermined ratio at a stirring speed of 400 rpm and a temperature of 80°C for 3 hours to obtain a uniformly mixed organic carrier.

[0107] (2) The Pb-Si-B glass powder, spherical copper powder with a particle size D50 of 1 μm and magnesium oxide powder with a particle size D50 of 1.1 μm are first mixed using a shear mixer, wherein the stirring speed is 80 rpm and the dispersion speed is 800 rpm, to obtain mixed powder.

[0108] (3) The mixed powder, dispersant, thixotropic agent, benzotriazole and organic carrier are centrifuged and dispersed for the first time using a high-speed centrifugal disperser at a speed of 4000 rpm and a centrifugation time of 5 times to obtain a solid-liquid mixed phase.

[0109] The solid-liquid mixture is ground and dispersed using a three-roll mill to obtain a ground slurry; in the three-roll mill, the speed ratio of the front roller, the middle roller and the rear roller is 3:6:4, and the speed of the middle roller is 400 rpm.

[0110] The ground slurry was subjected to a second centrifugal dispersion at a speed of 5000 rpm for 5 times to obtain the copper-based conductive electrode slurry.

[0111] The N-type back-contact solar cell and solar cell module provided in this embodiment are consistent with those in Embodiment 1.

[0112] Example 3

[0113] This embodiment provides a copper-based conductive electrode paste, which, by weight, comprises:

[0114] 90 parts of spherical copper powder, 3 parts of Pb-Si-B glass powder, 5 parts of organic carrier, 1 part of benzotriazole and 1 part of magnesium oxide powder.

[0115] The Pb-Si-B glass powder comprises, by weight percentage: 60% Pb3O4, 15% SiO2, 15% B2O3, and 10% ZnO. The organic carrier comprises ethyl cellulose, acrylic resin, butyl carbitol acetate, dodecayl alcohol ester, and butyl carbitol in a mass ratio of 8:2:20:30:40.

[0116] The copper-based conductive electrode paste also contains additives, which include a dispersant and a thixotropic agent in a mass ratio of 1:1. The dispersant is sodium tripolyphosphate and the thixotropic agent is polyamide wax. Based on the total mass of the spherical copper powder, Pb-Si-B glass powder, organic carrier, benzotriazole and magnesium oxide powder, the mass percentage of the additives is 4%.

[0117] The viscosity of the copper-based conductive electrode slurry is 2200 cP.

[0118] This embodiment also provides a method for preparing the copper-based conductive electrode paste as described above, the preparation method comprising the following steps:

[0119] (1) Provide Pb-Si-B glass powder with a particle size D50 of 1 μm. The preparation steps include:

[0120] Pb3O4, SiO2, B2O3, and ZnO were mixed in a predetermined ratio at a centrifugal speed of 1000 rpm, then placed in a ceramic crucible and placed in a muffle furnace. The mixture was heated to 1000°C at a heating rate of 10°C / min and calcined for 40 min to obtain liquid glass. The liquid glass was then quenched in ice water to transform it into solid glass. The liquid glass was then ball-milled, and the ball-milled glass fragments were then sand-milled to obtain the Pb-Si-B glass powder.

[0121] An organic carrier is provided, and the preparation steps include:

[0122] Ethyl cellulose, acrylic resin, butyl carbitol acetate, dodecayl alcohol ester and butyl carbitol were mixed at a predetermined ratio at a stirring speed of 800 rpm and a temperature of 70°C for 5 h to obtain a uniformly mixed organic carrier.

[0123] (2) The Pb-Si-B glass powder, spherical copper powder with a particle size D50 of 1 μm and magnesium oxide powder with a particle size D50 of 1.1 μm are first mixed using a shear mixer, wherein the stirring speed is 100 rpm and the dispersion speed is 1200 rpm, to obtain mixed powder.

[0124] (3) The mixed powder, dispersant, thixotropic agent, benzotriazole and organic carrier are centrifuged and dispersed for the first time using a high-speed centrifugal disperser at a speed of 6000 rpm and a centrifugation time of 5 times to obtain a solid-liquid mixed phase.

[0125] The solid-liquid mixture is ground and dispersed using a three-roll mill to obtain a ground slurry; in the three-roll mill, the speed ratio of the front roller, the middle roller and the rear roller is 3:6:4, and the speed of the middle roller is 600 rpm.

[0126] The ground slurry was subjected to a second centrifugal dispersion at a speed of 7000 rpm for 5 times to obtain the copper-based conductive electrode slurry.

[0127] The N-type back-contact solar cell and solar cell module provided in this embodiment are consistent with those in Embodiment 1.

[0128] Example 4

[0129] The difference between this embodiment and Embodiment 1 is that the amount of benzotriazole in the copper-based conductive electrode slurry is 0.5 parts, and the amount of adaptively adjusted spherical copper powder is 87.5 parts.

[0130] The remaining preparation methods and parameters are consistent with those in Example 1.

[0131] Example 5

[0132] The difference between this embodiment and Embodiment 1 is that the amount of benzotriazole in the copper-based conductive electrode slurry is 5 parts, and the amount of adaptively adjusted spherical copper powder is 84 parts.

[0133] The remaining preparation methods and parameters are consistent with those in Example 1.

[0134] Example 6

[0135] The difference between this embodiment and Embodiment 1 is that the amount of magnesium oxide powder in the copper-based conductive electrode slurry is 0.5 parts, and the amount of adaptively adjusted spherical copper powder is 87.5 parts.

[0136] The remaining preparation methods and parameters are consistent with those in Example 1.

[0137] Example 7

[0138] The difference between this embodiment and Embodiment 1 is that the amount of magnesium oxide powder in the copper-based conductive electrode slurry is 5 parts, and the amount of adaptively adjusted spherical copper powder is 84 parts.

[0139] The remaining preparation methods and parameters are consistent with those in Example 1.

[0140] Comparative Example 1

[0141] The difference between this comparative example and Example 1 is that benzotriazole and magnesium oxide powder are replaced with equal parts by weight of spherical copper powder.

[0142] The remaining preparation methods and parameters are consistent with those in Example 1.

[0143] Figure 1 and Figure 2 The diagrams show the TC200 test results of the solar cell modules provided in Example 1 and Comparative Example 1, respectively. As can be seen from the diagrams, in Example 1, the introduction of magnesium oxide powder and benzotriazole prevented the copper metal electrode from being corroded, while in Comparative Example 1, the above components were not introduced, resulting in a large area of ​​copper electrode corrosion.

[0144] Comparative Example 2

[0145] The difference between this comparative example and Example 1 is that benzotriazole is replaced with an equal part by weight of spherical copper powder.

[0146] The remaining preparation methods and parameters are consistent with those in Example 1.

[0147] Comparative Example 3

[0148] The difference between this comparative example and Example 1 is that magnesium oxide powder is replaced with an equal weight of spherical copper powder.

[0149] The remaining preparation methods and parameters are consistent with those in Example 1.

[0150] Comparative Example 4

[0151] The difference between this comparative example and Example 1 is that magnesium oxide powder is replaced with an equal part by weight of acidic oxide powder, wherein the acidic oxide powder is boron oxide.

[0152] The remaining preparation methods and parameters are consistent with those in Example 1.

[0153] Performance testing

[0154] After performing TC200 testing (compliant with IEC testing standards) on the solar cell modules provided in the above embodiments and comparative examples, EL testing (compliant with IEC testing standards) was then conducted. Using Example 1 as a benchmark, the Pmax degradation rate of other embodiments and comparative examples was recorded.

[0155] The results are shown in Table 1.

[0156] Table 1

[0157]

[0158] analyze:

[0159] As shown in Table 1, this invention simultaneously introduces alkaline oxide powder and organic corrosion inhibitor into the copper-based conductive electrode slurry, achieving synergistic protection of the copper electrode. The alkaline oxide powder, acting as an inorganic neutralizing agent, can neutralize the acetic acid produced during the aging process of the adhesive film, thus playing a "chemical repair" role. Meanwhile, the organic corrosion inhibitor, through its lone pairs of electrons, forms a dense, stable, and insoluble polymer protective film on the copper powder surface. This film effectively inhibits copper corrosion by acting as a barrier and altering the electrochemical interface properties, preventing damage to the copper electrode. The synergistic effect of these two agents constructs an effective physical and chemical protective barrier, significantly improving the acid corrosion resistance and long-term reliability of the copper electrode, thereby fundamentally avoiding the risk of component performance degradation or even failure caused by copper electrode corrosion.

[0160] A comparison of Examples 1 and 4-5 shows that if the amount of benzotriazole in the copper-based conductive electrode paste is too small, the copper electrode will be slightly acid-corroded after TC200, affecting its electrical performance after TC200. If the amount of benzotriazole in the copper-based conductive electrode paste is too large, the concentration will be too high, and the molecules may stack disordered, resulting in a loose and incomplete film layer that loses its protective function.

[0161] As can be seen from the comparison between Example 1 and Examples 6-7, if the amount of magnesium oxide powder in the copper-based conductive electrode paste is too small, the copper electrode will be slightly acid-corroded after TC200, affecting the electrical performance after TC200; if the amount of magnesium oxide powder in the copper-based conductive electrode paste is too large, it will fill the gaps between copper particles, affecting electron transport, and thus leading to a decrease in electrical performance.

[0162] As can be seen from the comparison between Example 1 and Comparative Example 1, if benzotriazole and magnesium oxide powder are not introduced, slurry detachment occurs during EL testing after TC200 testing, resulting in an 8.48% decrease in electrical performance compared to the Example.

[0163] As can be seen from the comparison between Example 1 and Comparative Examples 2-3, if benzotriazole is not introduced, a monomolecular adsorption film cannot be formed on the metal surface to provide protection, which leads to increased acid corrosion; if magnesium oxide powder is not introduced, it cannot neutralize the acid, causing acid molecules to directly contact the copper particles and causing the electrode to fail.

[0164] As can be seen from the comparison between Example 1 and Comparative Example 4, if magnesium oxide powder is replaced with an equal part by weight of acidic oxide powder, the acid neutralization effect is poor, the risk of electrode corrosion is increased, and the electrical performance decays significantly.

[0165] It should be noted that the present invention is illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A copper-based conductive electrode paste, characterized in that, The copper-based conductive electrode paste includes copper powder, glass powder, organic carrier, organic corrosion inhibitor and alkaline oxide powder; wherein the organic corrosion inhibitor includes benzotriazole.

2. The copper-based conductive electrode paste according to claim 1, characterized in that, The copper-based conductive electrode paste comprises, by weight, the following: 85-90 parts copper powder, 2-4 parts glass powder, 4-8 parts organic carrier, 1-3 parts organic corrosion inhibitor and 1-3 parts alkaline oxide powder; And / or, the alkaline oxide powder includes magnesium oxide powder.

3. The copper-based conductive electrode paste according to claim 1 or 2, characterized in that, The copper powder includes spherical copper powder; And / or, the glass powder includes Pb-Si-B based glass powder; And / or, the organic carrier includes a resin and a solvent.

4. The copper-based conductive electrode paste according to claim 3, characterized in that, The Pb-Si-B glass powder comprises, by weight percentage: 40-60% Pb3O4, 15-25% SiO2, 15-20% B2O3 and 5-15% ZnO; And / or, the resin includes ethyl cellulose and / or acrylic resin; And / or, the solvent includes any one or a combination of at least two of butyl carbitol acetate, dodecayl alcohol ester, or butyl carbitol; And / or, in the organic carrier, the mass ratio of resin to solvent is (5-15):(85-95).

5. The copper-based conductive electrode paste according to any one of claims 1-4, characterized in that, The copper-based conductive electrode paste also includes additives, including dispersants and / or thixotropic agents; Based on the total mass of the copper powder, glass powder, organic carrier, organic corrosion inhibitor, and alkaline oxide powder, the additive accounts for 2-4% of the total mass. And / or, the viscosity of the copper-based conductive electrode slurry is 2000-3000 cP.

6. A method for preparing a copper-based conductive electrode paste as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: Copper powder, glass powder, and alkaline oxide powder are first mixed to obtain a mixed powder. The mixed powder, organic corrosion inhibitor and organic carrier are mixed a second time to obtain the copper-based conductive electrode slurry; The organic corrosion inhibitor includes benzotriazole.

7. The preparation method according to claim 6, characterized in that, During the first mixing process, the stirring speed is 80-100 rpm and the dispersion speed is 800-1200 rpm; And / or, the second mixing includes a first centrifugal dispersion, a grinding dispersion, and a second centrifugal dispersion performed sequentially; And / or, during the second mixing process, additives are also added, including dispersants and / or thixotropic agents.

8. The preparation method according to claim 6 or 7, characterized in that, The preparation method includes the following steps: (1) Provide Pb-Si-B glass powder with a particle size D50 of 0.6-1 μm, the preparation steps include: Pb3O4, SiO2, B2O3 and ZnO are mixed at a centrifugal speed of 600-1000 rpm, and then calcined at 800-1000℃ for 40-80 min to obtain liquid glass; water quenching is then performed to transform the liquid glass into solid glass, followed by ball milling and sand milling to obtain the Pb-Si-B glass powder. An organic carrier is provided, and the preparation steps include: Ethyl cellulose, acrylic resin, butyl carbitol acetate, dodecyl alcohol ester and butyl carbitol are mixed at a stirring speed of 400-800 rpm and a temperature of 70-80℃ for 3-5 hours to obtain a uniformly mixed organic carrier. (2) The Pb-Si-B glass powder, spherical copper powder with a particle size D50 of 0.8-1.2μm and magnesium oxide powder with a particle size D50 of 1-1.2μm are mixed for the first time, wherein the stirring speed is 80-100rpm and the dispersion speed is 800-1200rpm, to obtain a mixed powder. (3) The mixed powder, additives, organic corrosion inhibitors and organic carriers are subjected to a first centrifugal dispersion at a speed of 4000-6000 rpm to obtain a solid-liquid mixed phase; wherein the organic corrosion inhibitor includes benzotriazole and the additives include dispersants and / or thixotropic agents. The solid-liquid mixture is ground and dispersed using a three-roll mill to obtain a ground slurry; in the three-roll mill, the speed ratio of the front roller, the middle roller and the rear roller is (2-4):(5-7):(3-5), and the speed of the middle roller is 400-600 rpm; The ground slurry is subjected to a second centrifugal dispersion at a speed of 5000-7000 rpm to obtain a copper-based conductive electrode slurry.

9. A back-contact solar cell, characterized in that, The copper electrode in the back contact solar cell is prepared using the copper-based conductive electrode paste as described in any one of claims 1-5.

10. A solar cell module, characterized in that, The solar cell module is prepared using at least one back-contact solar cell as described in claim 9.

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