Low-temperature cured copper paste as well as preparation method and application thereof

Abstract

The invention relates to the field of photovoltaic cells, and particularly discloses low-temperature cured copper paste and a preparation method and application thereof. The copper paste is prepared from the following raw material components in parts by weight: 85 to 95 parts of copper powder, 2 to 8 parts of a carrier, 2 to 5 parts of a solvent, 0.1 to 3 parts of a curing agent, 0.01 to 0.05 part of an accelerant, 0.5 to 1.5 parts of zinc borate, 0.1 to 0.5 part of nickel nitrate, 0.05 to 0.15 part of ethylenediamine, 0.05 to 0.15 part of diammonium hydrogen phosphate and 0.1 to 0.3 part of citric acid, wherein the purity of the copper powder is 99%-99.9%. The preparation method of the low-temperature cured copper paste comprises the following steps: respectively adding the curing agent, the accelerant, the solvent, the zinc borate, the nickel nitrate, the ethylenediamine, the diammonium hydrogen phosphate, the citric acid and other raw materials into the carrier, uniformly stirring and mixing, then adding the copper powder, mixing and stirring, grinding, and stirring to obtain the low-temperature cured copper paste.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic cells, and in particular to a low-temperature curing copper paste, a preparation method thereof, and applications thereof. Background Art

[0002] In the field of photovoltaic cells, metallized composite structures are key to achieving electrode connections. Copper paste, a crucial material in the metallization process, has a resistivity that directly impacts the electrical performance of photovoltaic cells after curing. In current technologies, optimizing the copper paste's composition and controlling the curing process are the primary factors influencing resistivity. Existing copper paste formulations, when cured, can oxidize copper at excessively high temperatures. This oxidation increases resistivity, limiting improvements in the electrical performance of photovoltaic cells. Summary of the Invention

[0003] In order to reduce the resistivity of the copper layer after curing, the present application provides a low-temperature curing copper paste and a preparation method and application thereof.

[0004] In the first aspect, the present application provides a low-temperature curing copper paste, which adopts the following technical solution: A low-temperature curing copper paste, wherein the raw materials of the copper paste include the following components in parts by weight: 85-95 parts of copper powder, 2-8 parts of a carrier, 2-5 parts of a solvent, 0.1-3 parts of a curing agent, 0.01-0.05 parts of an accelerator, 0.5-1.5 parts of zinc borate, 0.1-0.5 parts of nickel nitrate, 0.05-0.15 parts of ethylenediamine, 0.05-0.15 parts of diammonium hydrogen phosphate, and 0.1-0.3 parts of citric acid; wherein the purity of the copper powder is 99%-99.9%.

[0005] By adopting the above technical solution, nickel nitrate can improve the oxidation resistance of copper, ethylenediamine can improve the stability of copper ions, diammonium hydrogen phosphate plays a good deoxidation role, effectively preventing oxidation of the copper surface, and citric acid can form a stable complex with copper ions through its multiple carboxyl groups, forming a protective film on the copper surface, which can slow down the further oxidation of copper. High-purity copper powder is then selected to reduce the resistivity of the copper layer after curing, thereby improving the electrical performance of the photovoltaic cell.

[0006] In a specific embodiment, the raw materials of the copper paste further include 0.3 to 0.7 parts by weight of a filler, and the raw materials of the filler include graphene, carbon nanotubes, dopamine hydrochloride, and γ-aminopropyltriethoxysilane.

[0007] In a specific embodiment, the method for preparing the filler comprises the following steps: Graphene pretreatment: Graphene is ultrasonically dispersed in Tris buffer, followed by addition of dopamine hydrochloride, and the solution pH is adjusted to 8.5-10 to obtain a mixed solution A. The mixture is stirred for 10-14 hours, and then centrifuged, washed, and vacuum dried to obtain pretreated graphene; wherein the mass concentration of graphene in the mixed solution A is 0.5-1g / L; Carbon nanotube pretreatment: ultrasonically disperse the carbon nanotubes in Tris buffer, then add dopamine hydrochloride and adjust the solution pH to 8.5-10 to obtain a mixed solution B. Stir and react for 10-14 hours, then centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes; wherein the mass concentration of the carbon nanotubes in the mixed solution B is 0.5-1g / L; Compounding: ultrasonically disperse the pretreated graphene and pretreated carbon nanotubes in deionized water, then add γ-aminopropyltriethoxysilane, react at 70-90°C for 1.5-2.5h, filter, dry, and finally add hydrogen iodide solution for reduction, filter, wash, and dry to obtain a filler.

[0008] By adopting the above technical solution, graphene and carbon nanotubes are modified using dopamine hydrochloride and γ-aminopropyltriethoxysilane, so that the obtained fillers not only have good dispersibility but also have good conductivity. Adding them to copper slurry improves the conductivity of the copper slurry after curing.

[0009] In a specific embodiment, in the compounding step, the mass concentration of pretreated graphene in deionized water is 0.3-0.9 g / L, the mass concentration of pretreated carbon nanotubes in deionized water is 0.1-0.3 g / L, and the mass concentration of γ-aminopropyltriethoxysilane in deionized water is 0.5-1%.

[0010] By adopting the above technical solution, the ratio of pretreated graphene and pretreated carbon nanotubes, as well as the usage amount of γ-aminopropyltriethoxysilane, are further limited, thereby improving the performance of the obtained filler.

[0011] In a specific embodiment, the raw materials of the copper paste further include 0.05 to 0.15 parts by weight of nano-cerium oxide.

[0012] By adopting the above technical solution, nano-cerium oxide can capture oxygen free radicals and inhibit copper oxidation, and carbon nanotubes fill the gaps between copper particles and form a continuous conductive path with them.

[0013] In a specific embodiment, the raw materials of the copper slurry further include 0.3 to 0.5 parts by weight of aluminum dihydrogen phosphate and 0.05 to 0.15 parts by weight of 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0014] By adopting the above technical solution, aluminum dihydrogen phosphate can promote the densification of the copper slurry after solidification, and 1-ethyl-3-methylimidazolium tetrafluoroborate can reduce the slurry viscosity, improve leveling, and reduce porosity, thereby further improving the conductive properties of the copper slurry after solidification.

[0015] In a specific embodiment, the solvent includes a mixture of DBE and diethylene glycol butyl ether acetate.

[0016] In a specific embodiment, the carrier includes a mixture of diglycidyl hexahydrophthalate and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate.

[0017] In a second aspect, the present application provides a method for preparing a low-temperature solidified copper paste, which adopts the following technical solution: A method for preparing a low-temperature solidified copper paste comprises the following steps: The curing agent, accelerator, solvent, zinc borate, nickel nitrate, ethylenediamine, diammonium hydrogen phosphate, citric acid and other raw materials are respectively added to the carrier, stirred and mixed evenly, and then copper powder is added, mixed, stirred, ground and stirred to obtain a low-temperature solidified copper slurry.

[0018] By adopting the above technical solution, a curing agent, an accelerator, a solvent, zinc borate, nickel nitrate, ethylenediamine, diammonium hydrogen phosphate, citric acid and other raw materials are first added to a carrier, stirred, and then copper powder is added, stirred, ground and stirred again to obtain a low-temperature solidified copper slurry.

[0019] In a third aspect, the present application provides an application of a low-temperature curing copper paste, which adopts the following technical solution: An application of a low-temperature solidified copper paste comprises the following steps: The low-temperature curing copper paste is printed onto the battery cell, and then cured at 200-450° C. for 10-40 minutes under nitrogen or argon protection to obtain a metal structure.

[0020] By adopting the above technical solution, the curing temperature and time are further limited, and the process is carried out under nitrogen or argon protection, which can effectively alleviate copper oxidation, reduce the resistivity of the copper paste after curing, and improve the conductive performance.

[0021] In summary, this application includes at least one of the following beneficial technical effects: 1. In this application, nickel nitrate can improve the oxidation resistance of copper, ethylenediamine can improve the stability of copper ions, diammonium hydrogen phosphate has a good deoxidation effect, effectively preventing oxidation of the copper surface, and citric acid can form a stable complex with copper ions through its multiple carboxyl groups, forming a protective film on the copper surface, which can slow down the further oxidation of copper. The use of high-purity copper powder reduces the resistivity of the cured copper layer, thereby improving the electrical performance of the photovoltaic cell. 2. The method of the present application comprises first adding a curing agent, an accelerator, a solvent, zinc borate, nickel nitrate, ethylenediamine, diammonium hydrogen phosphate, citric acid and other raw materials to a carrier, stirring, then adding copper powder, stirring, grinding and stirring again to obtain a low-temperature solidified copper slurry; 3. The application in this application further limits the curing temperature and time, and is carried out under nitrogen or argon protection, which can effectively alleviate copper oxidation, reduce the resistivity of the copper paste after curing, and improve the conductive performance. DETAILED DESCRIPTION

[0022] The present application is further described in detail below with reference to the embodiments.

[0023] All raw materials in the examples can be obtained commercially. Dopamine hydrochloride has a CAS number of 62-31-7; curing agents include, but are not limited to, a mixture of one or more of methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, pyromellitic dianhydride, and trimellitic anhydride, preferably methylhexahydrophthalic anhydride in this application; and accelerators include, but are not limited to, a mixture of one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, DMP-30, triethylamine, diethanolamine, ethylamine trifluoride, and benzylamine trifluoride, preferably 2-ethyl-4-methylimidazole in this application.

[0024] Preparation Example Preparation Example 1 Preparation Example 1 provides a method for preparing a filler, comprising the following steps: Graphene pretreatment: Graphene was ultrasonically dispersed in Tris buffer, followed by addition of dopamine hydrochloride, and the solution was adjusted to pH 9 to obtain a mixed solution A. The mixture was stirred and reacted in a dark environment for 12 h, and then centrifuged, washed, and vacuum-dried at 60°C to obtain pretreated graphene. The mass concentration of graphene in the mixed solution A was 0.5 g / L; the molar concentration of the Tris buffer was 10 mM, and the pH was 8.5. Carbon nanotube pretreatment: The carbon nanotubes were ultrasonically dispersed in Tris buffer, followed by addition of dopamine hydrochloride to adjust the solution pH to 9.5 to obtain a mixed solution B. The mixture was stirred for 12 h, then centrifuged, washed, and vacuum dried at 60°C to obtain pretreated carbon nanotubes. The mass concentration of the carbon nanotubes in the mixed solution B was 0.5 g / L. The molar concentration of the Tris buffer was 10 mM and the pH was 8.5. Composite: Pretreated graphene and pretreated carbon nanotubes are ultrasonically dispersed in deionized water, followed by adding γ-aminopropyltriethoxysilane, reacting at 70°C for 2.5 hours, filtering, drying, and finally adding to hydrogen iodide solution for reduction for 6 hours with a solid-liquid ratio of 1:100, filtering, washing to neutrality, and drying at 60°C to obtain a filler; wherein the concentration of hydrogen iodide in the hydrogen iodide solution is 55wt%; the mass concentration of pretreated graphene in deionized water is 0.3g / L, the mass concentration of pretreated carbon nanotubes in deionized water is 0.1 / L, and the mass concentration of γ-aminopropyltriethoxysilane in deionized water is 0.5%.

[0025] Preparation Example 2 Preparation Example 2 provides a method for preparing a filler, comprising the following steps: Graphene pretreatment: Graphene was ultrasonically dispersed in Tris buffer, followed by addition of dopamine hydrochloride, and the solution was adjusted to pH 9.5 to obtain a mixed solution A. The mixture was stirred and reacted in a dark environment for 12 h, and then centrifuged, washed, and vacuum-dried at 60°C to obtain pretreated graphene. The mass concentration of graphene in the mixed solution A was 0.8 g / L; the molar concentration of the Tris buffer was 10 mM, and the pH was 8.5. Carbon nanotube pretreatment: The carbon nanotubes were ultrasonically dispersed in Tris buffer, followed by addition of dopamine hydrochloride to adjust the solution to pH 9 to obtain a mixed solution B. The mixture was stirred for 12 h, then centrifuged, washed, and vacuum-dried at 60°C to obtain pretreated carbon nanotubes. The mass concentration of the carbon nanotubes in the mixed solution B was 0.8 g / L. The molar concentration of the Tris buffer was 10 mM and the pH was 8.5. Composite: Pretreated graphene and pretreated carbon nanotubes are ultrasonically dispersed in deionized water, followed by adding γ-aminopropyltriethoxysilane, reacting at 80°C for 2h, filtering, drying, and finally adding to hydrogen iodide solution for reduction for 6h with a solid-liquid ratio of 1:100, filtering, washing until neutral, and drying at 60°C to obtain a filler; wherein the concentration of hydrogen iodide in the hydrogen iodide solution is 55wt%; the mass concentration of pretreated graphene in deionized water is 0.6g / L, the mass concentration of pretreated carbon nanotubes in deionized water is 0.2 / L, and the mass concentration of γ-aminopropyltriethoxysilane in deionized water is 0.8%.

[0026] Preparation Example 3 Preparation Example 3 provides a method for preparing a filler, comprising the following steps: Graphene pretreatment: Graphene was ultrasonically dispersed in Tris buffer, followed by addition of dopamine hydrochloride, and the solution was adjusted to pH 9.5 to obtain a mixed solution A. The mixture was stirred and reacted in a dark environment for 12 h, and then centrifuged, washed, and vacuum-dried at 60°C to obtain pretreated graphene. The mass concentration of graphene in the mixed solution A was 1 g / L; the molar concentration of the Tris buffer was 10 mM, and the pH was 8.5. Carbon nanotube pretreatment: The carbon nanotubes were ultrasonically dispersed in Tris buffer, followed by addition of dopamine hydrochloride to adjust the solution to pH 9 to obtain a mixed solution B. The mixture was stirred for 12 h, then centrifuged, washed, and vacuum-dried at 60°C to obtain pretreated carbon nanotubes. The mass concentration of the carbon nanotubes in the mixed solution B was 1 g / L. The molar concentration of the Tris buffer was 10 mM and the pH was 8.5. Composite: Pretreated graphene and pretreated carbon nanotubes are ultrasonically dispersed in deionized water, followed by adding γ-aminopropyltriethoxysilane, reacting at 90°C for 1.5 hours, filtering, drying, and finally adding to a hydrogen iodide solution for reduction for 6 hours with a solid-liquid ratio of 1:100, filtering, washing to neutrality, and drying at 60°C to obtain a filler; wherein the concentration of hydrogen iodide in the hydrogen iodide solution is 55wt%; the mass concentration of pretreated graphene in deionized water is 0.9g / L, the mass concentration of pretreated carbon nanotubes in deionized water is 0.3 / L, and the mass concentration of γ-aminopropyltriethoxysilane in deionized water is 1%. Example

[0027] Example 1 Example 1 provides a method for preparing a low-temperature solidified copper paste, comprising the following steps: 0.1g curing agent, 0.01g accelerator, 2g solvent, 0.5g zinc borate, 0.1g nickel nitrate, 0.05g ethylenediamine, 0.05g diammonium hydrogen phosphate, and 0.1g citric acid were added to 2g carrier respectively, and stirred to mix evenly. Then, 85g copper powder with a purity of 99.9% was added, mixed, ground, and stirred to obtain a low-temperature curing copper slurry; wherein the curing agent is methylhexahydrophthalic anhydride; the accelerator is 2-ethyl-4- Methylimidazole; the solvent is a mixture of DBE and diethylene glycol butyl ether acetate, and the weight ratio of DBE to diethylene glycol butyl ether acetate is 1.4:0.6; the carrier is a mixture of diglycidyl hexahydrophthalate and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, and the weight ratio of diglycidyl hexahydrophthalate and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate is 1.8:1.

[0028] Example 2 The difference between Example 2 and Example 1 is that 1.5 g of curing agent, 0.03 g of accelerator, 3.5 g of solvent, 1 g of zinc borate, 0.3 g of nickel nitrate, 0.1 g of ethylenediamine, 0.1 g of diammonium hydrogen phosphate, and 0.2 g of citric acid are added to 5 g of the carrier, stirred and mixed uniformly, and then 90 g of copper powder with a purity of 99.9% is added, mixed, ground, and stirred to obtain a low-temperature cured copper slurry; the remaining steps are consistent with Example 1.

[0029] Example 3 The difference between Example 3 and Example 1 is that 3 g of curing agent, 0.05 g of accelerator, 5 g of solvent, 1.5 g of zinc borate, 0.5 g of nickel nitrate, 0.15 g of ethylenediamine, 0.15 g of diammonium hydrogen phosphate, and 0.1 g of citric acid are added to 2 g of the carrier, stirred and mixed uniformly, and then 85 g of copper powder with a purity of 99.9% is added, mixed, ground, and stirred to obtain a low-temperature cured copper slurry; the remaining steps are consistent with Example 1.

[0030] Example 4 The difference between Example 4 and Example 2 is that 1.5 g of curing agent, 0.03 g of accelerator, 3.5 g of solvent, 1 g of zinc borate, 0.3 g of nickel nitrate, 0.1 g of ethylenediamine, 0.1 g of diammonium hydrogen phosphate, 0.2 g of citric acid, and 0.5 g of the filler in Preparation Example 1 are added to 5 g of the carrier, stirred and mixed uniformly, and then 90 g of copper powder with a purity of 99.9% is added, mixed, ground, and stirred to obtain a low-temperature cured copper slurry; the remaining steps are consistent with Example 2.

[0031] Example 5 The difference between Example 5 and Example 2 is that 1.5 g of curing agent, 0.03 g of accelerator, 3.5 g of solvent, 1 g of zinc borate, 0.3 g of nickel nitrate, 0.1 g of ethylenediamine, 0.1 g of diammonium hydrogen phosphate, 0.2 g of citric acid, and 0.5 g of the filler in Preparation Example 2 are added to 5 g of the carrier, stirred and mixed evenly, and then 90 g of copper powder with a purity of 99.9% is added, mixed, ground, and stirred to obtain a low-temperature cured copper slurry; the remaining steps are consistent with Example 2.

[0032] Example 6 The difference between Example 6 and Example 2 is that 1.5 g of curing agent, 0.03 g of accelerator, 3.5 g of solvent, 1 g of zinc borate, 0.3 g of nickel nitrate, 0.1 g of ethylenediamine, 0.1 g of diammonium hydrogen phosphate, 0.2 g of citric acid, and 0.5 g of the filler in Preparation Example 3 are added to 5 g of the carrier, stirred and mixed evenly, and then 90 g of copper powder with a purity of 99.9% is added, mixed, ground, and stirred to obtain a low-temperature cured copper slurry; the remaining steps are consistent with Example 2.

[0033] Example 7 The difference between Example 7 and Example 5 is that 1.5 g of curing agent, 0.03 g of accelerator, 3.5 g of solvent, 1 g of zinc borate, 0.3 g of nickel nitrate, 0.1 g of ethylenediamine, 0.1 g of diammonium hydrogen phosphate, 0.2 g of citric acid, 0.5 g of the filler in Preparation Example 2, and 0.1 g of nano-cerium oxide are added to 5 g of the carrier and stirred to mix evenly, and then 90 g of copper powder with a purity of 99.9% is added, mixed, ground, and stirred to obtain a low-temperature cured copper slurry; the remaining steps are consistent with Example 5.

[0034] Example 8 The difference between Example 8 and Example 7 is that 1.5 g of curing agent, 0.03 g of accelerator, 3.5 g of solvent, 1 g of zinc borate, 0.3 g of nickel nitrate, 0.1 g of ethylenediamine, 0.1 g of diammonium hydrogen phosphate, 0.2 g of citric acid, 0.5 g of the filler in Preparation Example 2, 0.1 g of nano-cerium oxide, 0.4 g of aluminum dihydrogen phosphate, and 0.1 g of 1-ethyl-3-methylimidazolium tetrafluoroborate are added to 5 g of the carrier and stirred to mix evenly, followed by adding 90 g of copper powder with a purity of 99.9%, mixing, grinding, and stirring to obtain a low-temperature cured copper slurry; the remaining steps are consistent with Example 7.

[0035] Example 9 The difference between Example 9 and Example 1 is that 0.1g of curing agent, 0.01g of accelerator, 2g of solvent, 0.5g of zinc borate, 0.1g of nickel nitrate, 0.05g of ethylenediamine, 0.05g of diammonium hydrogen phosphate, and 0.1g of citric acid are added to 2g of the carrier, stirred and mixed evenly, and then 85g of copper powder with a purity of 99% is added, mixed, ground, and stirred to obtain a low-temperature cured copper slurry; the remaining steps are consistent with Example 1.

[0036] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that: 0.1g of curing agent, 0.01g of accelerator, 2g of solvent, 0.5g of zinc borate, 0.1g of nickel nitrate, 0.05g of ethylenediamine, 0.05g of diammonium hydrogen phosphate, and 0.1g of citric acid are respectively added to 2g of the carrier, stirred and mixed uniformly, and then 85g of copper powder with a purity of 98% is added, mixed, ground, and stirred to obtain a low-temperature cured copper slurry; the remaining steps are consistent with Example 1.

[0037] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that: 0.1g of curing agent, 0.01g of accelerator, 2g of solvent, and 0.5g of zinc borate are respectively added to 2g of carrier, stirred and mixed evenly, and then 85.3g of copper powder with a purity of 99.9% is added, mixed, ground, and stirred to obtain a low-temperature cured copper slurry; the remaining steps are consistent with Example 1.

[0038] Application Examples Application Example 1 Application Example 1 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 1 was printed onto the cell and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0039] Application Example 2 Application Example 2 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 2 was printed onto the cell, and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0040] Application Example 3 Application Example 3 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 3 was printed onto the cell, and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0041] Application Example 4 Application Example 4 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 4 was printed onto the cell and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0042] Application Example 5 Application Example 5 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 5 was printed onto the cell and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0043] Application Example 6 Application Example 6 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 6 was printed onto the cell and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0044] Application Example 7 Application Example 7 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 7 was printed onto the cell and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0045] Application Example 8 Application Example 8 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 8 was printed onto the cell and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0046] Application Example 9 Application Example 9 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 9 was printed onto the cell and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0047] Application Example 10 Application Example 10 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 1 was printed onto the cell, and then cured at 200° C. for 40 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0048] Application Example 11 Application Example 11 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 1 was printed onto the cell, and then cured at 250° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0049] Application Example 12 Application Example 12 provides an application of a low-temperature curing copper paste, comprising the following steps: The low-temperature curing copper paste in Example 1 was printed onto the cell, and then cured at 450° C. for 10 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0050] Comparative Application Examples Comparative Application Example 1 Comparative Application Example 1 provides an application of a low-temperature solidified copper paste, comprising the following steps: The low-temperature cured copper paste in Comparative Example 1 was printed onto the cell and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0051] Comparative Application Example 2 Comparative Application Example 2 provides an application of a low-temperature solidified copper paste, comprising the following steps: The low-temperature cured copper paste in Comparative Example 2 was printed onto the cell and then cured at 300° C. for 30 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0052] Comparative Application Example 3 Comparative Application Example 3 provides an application of a low-temperature solidified copper paste, comprising the following steps: The low-temperature curing copper paste in Example 1 was printed onto the cell and then cured at 150° C. for 45 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0053] Comparative Application Example 4 Comparative Application Example 4 provides an application of a low-temperature solidified copper paste, comprising the following steps: The low-temperature curing copper paste in Example 1 was printed onto the cell, and then cured at 500° C. for 5 minutes under nitrogen protection to obtain a metal structure with a thickness of 10 μm.

[0054] Performance test resistivity: The metal structures in each application example and comparative application example were tested in accordance with GB / T17473.3-2008 to obtain resistivity. The lower the resistivity, the better the conductive performance of the metal structure.

[0055] Table 1 Performance test results of metal structures Combining Application Example 1, Application Example 9 and Comparative Application Examples 1-2, it can be seen that when preparing copper slurry, copper powder with a purity of 99%-99.9% is selected, and nickel nitrate, ethylenediamine, diammonium hydrogen phosphate, and citric acid are added. Nickel nitrate and ethylenediamine can improve the stability of copper ions, diammonium hydrogen phosphate can effectively prevent copper surface oxidation, and citric acid can form a stable complex with copper ions through its multiple carboxyl groups to form a protective film on the copper surface, which can slow down the further oxidation of copper, thereby reducing the resistivity of the copper layer after curing, thereby improving its conductive properties.

[0056] Combined with Application Examples 1-3, it can be seen that when preparing the copper paste according to the ratio in Examples 1-3, the obtained copper paste has better conductive properties.

[0057] Combining Application Example 2 and Application Example 4, the conductive properties of the copper paste in Application Example 4 are better. It can be seen that when preparing the copper paste, a filler modified with dopamine hydrochloride is added to the raw material, and graphene and carbon nanotubes are modified using dopamine hydrochloride and γ-aminopropyltriethoxysilane, so that the filler not only has good dispersibility but also has good conductive properties, thereby improving the conductive properties of the copper paste after curing.

[0058] Combined with Application Examples 4-6, the conductive performance of the copper paste in Application Example 5 is the best. It can be seen that when preparing the filler, according to the raw material ratio in Preparation Example 2, the performance of the filler obtained is better.

[0059] Combining Application Example 5 and Application Example 7, the conductive properties of the copper paste in Application Example 7 are better. It can be seen that when preparing the copper paste, nano-cerium oxide is added to the raw materials. Nano-cerium oxide can capture oxygen free radicals, inhibit copper oxidation, and further improve the conductive properties of the copper paste after curing.

[0060] Combining Application Examples 7 and 8, the conductive properties of the copper paste in Application Example 8 are better. It can be seen that when preparing the copper paste, aluminum dihydrogen phosphate and 1-ethyl-3-methylimidazolium tetrafluoroborate are added to the raw materials. Aluminum dihydrogen phosphate can promote the densification of the copper paste after solidification, and 1-ethyl-3-methylimidazolium tetrafluoroborate reduces the slurry viscosity, improves leveling, and reduces porosity, thereby further improving the conductive properties of the copper paste after solidification.

[0061] Combining Application Example 1, Application Examples 10-12 and Comparative Application Examples 3-4, it can be seen that when the copper paste is heated and cured, the curing temperature is preferably 200-450° C., and the conductive properties of the cured copper paste are better.

[0062] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A low-temperature curing copper paste, characterized in that: The raw materials of the copper slurry include the following components in parts by weight: 85-95 parts of copper powder, 2-8 parts of a carrier, 2-5 parts of a solvent, 0.1-3 parts of a curing agent, 0.01-0.05 parts of an accelerator, 0.5-1.5 parts of zinc borate, 0.1-0.5 parts of nickel nitrate, 0.05-0.15 parts of ethylenediamine, 0.05-0.15 parts of diammonium hydrogen phosphate, and 0.1-0.3 parts of citric acid; The purity of the copper powder is 99%-99.9%.

2. The low-temperature curing copper paste according to claim 1, characterized in that: The raw materials of the copper paste further include 0.3 to 0.7 parts by weight of filler, and the raw materials of the filler include graphene, carbon nanotubes, dopamine hydrochloride, and gamma-aminopropyltriethoxysilane.

3. The low-temperature curing copper paste according to claim 2, characterized in that: The preparation method of the filler comprises the following steps: Graphene pretreatment: Graphene is ultrasonically dispersed in Tris buffer, followed by addition of dopamine hydrochloride, and the solution pH is adjusted to 8.5-10 to obtain a mixed solution A. The mixture is stirred for 10-14 hours, and then centrifuged, washed, and vacuum dried to obtain pretreated graphene; wherein the mass concentration of graphene in the mixed solution A is 0.5-1g / L; Carbon nanotube pretreatment: ultrasonically disperse the carbon nanotubes in Tris buffer, then add dopamine hydrochloride and adjust the solution pH to 8.5-10 to obtain a mixed solution B. Stir and react for 10-14 hours, then centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes; wherein the mass concentration of the carbon nanotubes in the mixed solution B is 0.5-1g / L; Compounding: ultrasonically disperse the pretreated graphene and pretreated carbon nanotubes in deionized water, then add γ-aminopropyltriethoxysilane, react at 70-90°C for 1.5-2.5h, filter, dry, and finally add hydrogen iodide solution for reduction, filter, wash, and dry to obtain a filler.

4. The low-temperature curing copper paste according to claim 3, characterized in that: In the compounding step, the mass concentration of the pretreated graphene in deionized water is 0.3-0.9 g / L, the mass concentration of the pretreated carbon nanotubes in deionized water is 0.1-0.3 g / L, and the mass concentration of γ-aminopropyltriethoxysilane in deionized water is 0.5-1%.

5. The low-temperature curing copper paste according to claim 4, characterized in that: The raw materials of the copper paste also include 0.05-0.15 parts by weight of nano-cerium oxide.

6. The low-temperature curing copper paste according to claim 1, characterized in that: The raw materials of the copper slurry further include 0.3-0.5 parts by weight of aluminum dihydrogen phosphate and 0.05-0.15 parts by weight of 1-ethyl-3-methylimidazolium tetrafluoroborate.

7. The low-temperature curing copper paste according to claim 1, characterized in that: The solvent includes a mixture of DBE and diethylene glycol butyl ether acetate.

8. The low-temperature curing copper paste according to claim 1, characterized in that: The carrier comprises a mixture of diglycidyl hexahydrophthalate and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate.

9. A method for preparing a low-temperature curing copper paste according to any one of claims 1 to 8, characterized in that: The following steps are involved: The curing agent, accelerator, solvent, zinc borate, nickel nitrate, ethylenediamine, diammonium hydrogen phosphate, citric acid and other raw materials are respectively added to the carrier, stirred and mixed evenly, and then copper powder is added, mixed, stirred, ground and stirred to obtain a low-temperature solidified copper slurry.

10. An application of the low temperature curing copper paste according to any one of claims 1 to 8, wherein The method comprises the following steps: The low-temperature curing copper paste is printed onto the battery cell, and then cured at 200-450° C. for 10-40 minutes under nitrogen or argon protection to obtain a metal structure.

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