Production method of functional current collector with high binding force
By etching the polypropylene film and depositing a silver layer under ultraviolet radiation, combined with a pretreatment step, the problem of insufficient silver layer adhesion in the production of functional current collectors was solved, thereby improving the safety and energy density of the battery.
Patent Information
- Application Number
- CN202511416068.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2025-12-26
AI Technical Summary
In existing methods for producing functional current collectors, the copper layer film obtained by magnetron sputtering has poor adhesion and is easily peeled off from the base film, affecting the safety and energy density of the battery.
By etching the polypropylene film and depositing a silver layer using ultraviolet radiation, combined with pretreatment steps such as radiation grafting of acrylic acid and synthetic polymers, the adhesion between the silver layer and the polypropylene film is improved, promoting uniform silver deposition and a higher yield in the electroplating process.
It enhances the silver layer adhesion and conductivity of the functional current collector, reduces defects in the electroplating process, and improves battery safety and energy density.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of functional current collector production technology, specifically a method for producing functional current collectors with high bonding strength. Background Technology
[0002] With the rapid development of new energy and advanced manufacturing, the key performance characteristics of batteries, such as cycle life, safety, and energy density, urgently need to be improved. Current collectors are a crucial component of batteries, serving to collect current; their performance directly affects the battery's cycle life, energy density, safety, and other technical indicators.
[0003] Currently, most current collectors used in the battery industry are made of copper or aluminum foil. Current collectors made of pure metals are costly and heavy, and their performance in terms of battery safety is often unsatisfactory. Furthermore, pure metal current collectors have a high "dead weight," which is detrimental to improving battery energy density. In this context, composite conductive foils offer significant advantages. Composite foil current collectors typically have a "sandwich" structure, with an inner polymer layer and metal conductive layers on both sides. The metal layer on the surface of the functional current collector is thinner, and the density of the polymer layer in the middle is significantly lower than that of pure metal, thus significantly reducing the weight of the current collector and improving the battery's energy density. In the event of thermal runaway, functional current collectors are easier to disconnect than traditional current collectors, thereby isolating the active material from the current collector and preventing further thermal runaway.
[0004] Although functional current collectors offer advantages such as low cost and high safety, their production process often presents challenges. Traditional methods involve two steps: magnetron sputtering, which aims to create a highly conductive seed layer on the surface of a non-conductive polymer film, and electroplating, which thickens the magnetron-sputtered film to meet process requirements. However, for polypropylene films lacking free radicals, the copper layer obtained through magnetron sputtering exhibits poor adhesion and is easily peeled off from the base film. Therefore, improvements to the manufacturing process are necessary to address this issue. Summary of the Invention
[0005] The purpose of this invention is to provide a method for producing functional current collectors with high bonding strength, so as to solve the problems raised in the prior art.
[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for producing a functional current collector with high bonding strength includes the following steps: Step 1: After etching, alkali washing and drying, the polypropylene film is placed in a silver deposition solution and subjected to ultraviolet radiation deposition to obtain a silver-coated polypropylene film. Step 2: Immerse the silver-coated polypropylene film prepared in Step 1 into the electroplating solution. After the copper plating layer on the surface thickens to 1 μm, wash with water and dry to obtain the functional current collector.
[0007] Preferably, in step 1, the etching process uses 6.5% K2Cr2O7 and 93.5% H2SO4 by mass, and the etching process lasts for 3-5 minutes. Preferably, the silver deposition solution comprises silver nitrate, ascorbic acid, gelatin, and deionized water; the ratio of ascorbic acid to silver nitrate is 2:1, the concentration of silver nitrate is 25-30 g / L, and the concentration of gelatin is 1-3 g / L. Preferably, the radiative flux in step 1 is 900-1100 W / m². 2 The deposition time is 10-15 minutes; More preferably, the method for producing functional current collectors further includes pretreatment of the polypropylene membrane after alkali washing and drying, specifically including the following steps: Step S1: Place the polypropylene membrane after alkaline washing and drying in step 1 into an acrylic grafting solution at a solid-liquid ratio of 1:(40-60). After vacuuming, nitrogen gas is introduced every 10 minutes. After ultraviolet irradiation, the membrane is washed with alcohol and water alternately 2-3 times to obtain a carboxyl functionalized polypropylene membrane. Step S2: Under a protective atmosphere, a mixed solution of diethylenetriamine and methanol is slowly added dropwise to methyl acrylate. After reacting for 24 hours, the mixture is vacuum filtered at 65℃-70℃ for 1 hour. The temperature is then increased by 10℃ for 1 hour each time, and the mixture is kept at 140℃ for 4 hours to obtain a hyperbranched polymer. Water is added and the mixture is stirred to obtain an aqueous solution of the hyperbranched polymer. Step S3: Immerse the carboxyl-functionalized polypropylene membrane prepared in S1 into the aqueous solution of the hyperbranched polymer prepared in S2, with a solid-liquid ratio of 1:(50-60). Add EDC hydrochloride and N-hydroxysuccinimide, stir and react for 1-3 hours, wash with alcohol and water alternately, and then dry.
[0008] Preferably, the preparation step of the acrylic acid grafting solution in step S1 includes: ultrasonicating an aqueous solution of ferrous ammonium sulfate and a benzophenone alcohol solution for 3 min-5 min, adding acrylic acid, and then ultrasonicating for 1 min-2 min to obtain the solution; wherein the mass fraction of acrylic acid in the acrylic acid grafting solution is 10%-25%; the ultraviolet irradiation temperature is 60℃-80℃, and the irradiation time is 30-40 min; Preferably, the molar ratio of diethylenetriamine to methyl acrylate in step S2 is 1:1; A method for producing a functional current collector with high bonding strength, and its application in the battery industry.
[0009] Compared with the prior art, the beneficial effects of the present invention are: 1. The current collector of this invention is obtained by etching a PP film, irradiating and chemically plating silver, and then electroplating a copper layer. Specifically, the polypropylene film is subjected to a certain etching pretreatment to enhance the surface roughness of the film. Then, ultraviolet light irradiation is used to assist in the chemical deposition of a silver layer, which promotes uniform deposition of the silver layer and enhances the areal density and compactness of the silver layer. This improves the peel strength of the functional current collector and makes the surface silver layer uniform in color, reducing appearance defects. A conductive silver layer with excellent adhesion and conductivity is successfully prepared on the surface of the polypropylene film. In the subsequent electroplating process, the excellent conductivity of the silver layer effectively reduces the defects that may occur during the electroplating process, improves the yield of electroplated products, and helps to speed up and improve the quality of products. On the other hand, it facilitates the deposition of copper ions in the subsequent copper electroplating, improving the yield of functional current collector products.
[0010] 2. This invention pretreats the polypropylene film before silver deposition, including radiation grafting of acrylic acid to functionalize the polypropylene film, and then grafting it with a polymer synthesized from methyl acrylate and diethylenetriamine, introducing a large number of active groups containing nitrogen and oxygen atoms. In the subsequent silver plating, silver can be adsorbed around the groups through coordination bonds, improving the adhesion between the silver layer and the polypropylene film. Furthermore, the grafted polymer can adsorb silver ions through electrostatic or complexation while also donating electrons to reduce silver ions, further accelerating the silver deposition rate. The pretreatment improves the wettability of the film, bringing improvement and promotion effects to the subsequent silver deposition. Detailed Implementation
[0011] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0012] In the experiment, the etching solution consisted of 6.5% K2Cr2O7 and 93.5% H2SO4 by mass. The copper plating solution comprises: 180 g / L copper sulfate, 120 g / L sulfuric acid, 100 mg / L hydrochloric acid, 50 mg / L leveling agent, 700 mg / L inhibitor, and 5 mg / L brightener; the brightener is SPS, purchased from Kunshan Aichao Biotechnology; the inhibitor is PEG8000, purchased from Jiangsu Mengde Electroplating Chemicals Co., Ltd.; and the leveling agent is JGB, purchased from Shanghai Aladdin. Example 1: This example provides a method for producing a functional current collector with high bonding strength. The specific steps are as follows: Step 1: Place a 4.5 μm thick polypropylene film in the etching solution and etch for 3 minutes. After alkaline washing and drying, place it in a silver deposition solution and turn on the ultraviolet radiation lamp with a radiation flux of 1000 W / m. 2 The irradiation time was 14 minutes, and a silver-coated polypropylene film was obtained. Step 2: Electroplating copper onto the surface of the silver-coated polypropylene film. After the copper layer on the surface has thickened to 1 μm, wash with water and dry to obtain the functional current collector. The silver deposition solution includes: 28 g / L silver nitrate, 56 g / L ascorbic acid, and 2 g / L gelatin. Example 2: This example provides a method for producing a functional current collector with high bonding strength. The specific steps are as follows: Step 1: Place a 4.5 μm thick polypropylene film in the etching solution and etch for 3 minutes. After alkaline washing and drying, place it in a silver deposition solution and turn on the ultraviolet radiation lamp with a radiation flux of 1000 W / m. 2 The irradiation time was 13 minutes, and a silver-coated polypropylene film was obtained. Step 2: Electroplating copper onto the surface of the silver-coated polypropylene film. After the copper layer on the surface has thickened to 1 μm, wash with water and dry to obtain the functional current collector. The silver deposition solution consists of 25 g / L silver nitrate, 50 g / L ascorbic acid, and 1 g / L gelatin. Example 3: This example provides a method for producing a functional current collector with high bonding strength. The specific steps are as follows: Step 1: Take a 4.5μm thick polypropylene film, etch it in the etching solution for 5 minutes, wash it with alkali and dry it, then place it in the silver deposition solution and turn on the ultraviolet radiation lamp with a radiation flux of 1000W / m. 2 The irradiation time was 13 minutes, and a silver-coated polypropylene film was obtained. Step 2: Electroplating copper onto the surface of the silver-coated polypropylene film. After the copper layer on the surface has thickened to 1 μm, wash with water and dry to obtain the functional current collector. The silver deposition solution consists of 30 g / L silver nitrate, 60 g / L ascorbic acid, and 3 g / L gelatin. Example 4: This example provides a method for producing a functional current collector with high bonding strength. The specific steps are as follows: Step 1: Take a 4.5μm thick polypropylene film, etch it in the etching solution for 4 minutes, wash it with alkali and dry it, then place it in the silver deposition solution and turn on the ultraviolet radiation lamp with a radiation flux of 900W / m. 2 The irradiation time was 10 minutes, and a silver-coated polypropylene film was obtained. Step 2: Electroplating copper onto the surface of the silver-coated polypropylene film. After the copper layer on the surface has thickened to 1 μm, wash with water and dry to obtain the functional current collector. The silver deposition solution consists of 28 g / L silver nitrate, 56 g / L ascorbic acid, and 2 g / L gelatin. Example 5: This example provides a method for producing a functional current collector with high bonding strength. The specific steps are as follows: Step 1: Take a 4.5μm thick polypropylene film, etch it in the etching solution for 4 minutes, wash it with alkali and dry it, then place it in the silver deposition solution and turn on the ultraviolet radiation lamp with a radiation flux of 1100W / m. 2 The irradiation time was 15 minutes, and a silver-coated polypropylene film was obtained. Step 2: Electroplating copper onto the surface of the silver-coated polypropylene film. After the copper layer on the surface has thickened to 1 μm, wash with water and dry to obtain the functional current collector. The silver deposition solution consists of 28 g / L silver nitrate, 56 g / L ascorbic acid, and 2 g / L gelatin. Example 6: This example provides a method for producing a functional current collector with high bonding strength. The specific steps are as follows: Step 1: Take a 4.5μm thick polypropylene film and etch it in the etching solution for 3 minutes. After alkali washing and drying, perform pretreatment. Place it in acrylic grafting solution with a solid-liquid ratio of 1:60. After vacuuming, nitrogen gas is introduced every 10 minutes. Irradiate it with ultraviolet light at 60℃ for 30 minutes. Wash it with alcohol and water alternately 3 times to obtain a carboxyl functionalized polypropylene film. Step 2: Under a nitrogen atmosphere, 51.5g of diethylenetriamine and 100g of methanol mixed solution were slowly added dropwise to 43.1g of methyl acrylate. After reacting for 24h, the mixture was vacuum filtered at 70℃ for 1h. The temperature was then increased by 10℃ for 1h, and the mixture was kept at 140℃ for 4h to obtain hyperbranched polymer. Water was added and mixed, and the mixture was stirred to obtain a 100g / L hyperbranched polymer aqueous solution. Step 3: Immerse the carboxyl-functionalized polypropylene membrane prepared by S1 in an aqueous solution of the hyperbranched polymer prepared by S2, with a solid-liquid ratio of 1:50. Add 0.10g of EDC hydrochloride and 0.06g of N-hydroxysuccinimide, stir and react for 2 hours. After washing with alternating alcohol and water, dry the membrane and place it in a silver deposition solution. Turn on the ultraviolet radiation lamp with a radiant flux of 1000W / m. 2 The irradiation time was 14 minutes, and a silver-coated polypropylene film was obtained. Step 4: Electroplat copper onto the surface of the silver-coated polypropylene film. After the copper layer on the surface has thickened to 1 μm, wash with water and dry to obtain the functional current collector. In step 1, the acrylic acid grafting solution is prepared by mixing a 0.5% ferrous ammonium sulfate aqueous solution and a 0.5% benzophenone alcohol solution at a volume ratio of 5:1, sonicating for 3 minutes, adding acrylic acid, and then sonicating for another 2 minutes; the mass fraction of acrylic acid in the acrylic acid grafting solution is 10%. In step 3, the silver deposition solution consists of 28 g / L silver nitrate, 56 g / L ascorbic acid, and 2 g / L gelatin. Example 7: This example provides a method for producing a functional current collector with high bonding strength. The specific steps are as follows: Step 1: Take a 4.5 μm thick polypropylene film and etch it in the etching solution for 3 min. After alkali washing and drying, perform pretreatment. Place it in acrylic grafting solution with a solid-liquid ratio of 1:60. After vacuuming, nitrogen gas is introduced every 10 min. Irradiate it with ultraviolet light at 80℃ for 40 min. Wash it with alcohol and water alternately 3 times to obtain a carboxyl functionalized polypropylene film. Step 2: Under a nitrogen atmosphere, 51.5g of diethylenetriamine and 100g of methanol mixed solution were slowly added dropwise to 43.1g of methyl acrylate. After reacting for 24h, the mixture was vacuum filtered at 70℃ for 1h. The temperature was then increased by 10℃ for 1h, and the mixture was kept at 140℃ for 4h to obtain hyperbranched polymer. Water was added and mixed, and the mixture was stirred to obtain a 100g / L hyperbranched polymer aqueous solution. Step 3: Immerse the carboxyl-functionalized polypropylene membrane prepared by S1 in an aqueous solution of the hyperbranched polymer prepared by S2, with a solid-liquid ratio of 1:50. Add 0.10g of EDC hydrochloride and 0.06g of N-hydroxysuccinimide, stir and react for 2 hours. After washing with alternating alcohol and water, dry the membrane and place it in a silver deposition solution. Turn on the ultraviolet radiation lamp with a radiant flux of 1000W / m. 2 The irradiation time was 14 minutes, and a silver-coated polypropylene film was obtained. Step 4: Electroplat copper onto the surface of the silver-coated polypropylene film. After the copper layer on the surface has thickened to 1 μm, wash with water and dry to obtain the functional current collector. In step 1, the acrylic acid grafting solution is prepared by mixing a 0.5% ferrous ammonium sulfate aqueous solution and a 0.5% benzophenone alcohol solution at a volume ratio of 5:1, sonicating for 5 minutes, adding acrylic acid, and then sonicating for another 2 minutes; the mass fraction of acrylic acid in the acrylic acid grafting solution is 25%. In step 3, the silver deposition solution consists of 28 g / L silver nitrate, 56 g / L ascorbic acid, and 2 g / L gelatin. Comparative Example 1: As a control experiment for Example 1, no ultraviolet radiation was applied; the specific steps are as follows: Step 1: Take a 4.5μm thick polypropylene film, etch it in the etching solution for 3 minutes, wash it with alkali and dry it, then place it in the silver deposition solution for 14 minutes to obtain a silver-coated polypropylene film. Step 2: Electroplating copper onto the surface of the silver-coated polypropylene film. After the copper layer on the surface has thickened to 1 μm, wash with water and dry to obtain the functional current collector. The silver deposition solution includes: 28 g / L silver nitrate, 56 g / L ascorbic acid, and 2 g / L gelatin. Comparative Example 2: As a control experiment for Example 1, no silver plating treatment was performed. The specific steps are as follows: A 4.5 μm thick polypropylene film was placed in an etching solution and etched for 3 minutes. After being washed with alkali and dried, copper was electroplated on the surface of the polypropylene film. After the copper layer on the surface thickened to 1 μm, it was washed with water and dried to obtain a functional current collector. The silver deposition solution includes: 28 g / L silver nitrate, 56 g / L ascorbic acid, and 2 g / L gelatin. Comparative Example 3: As a control experiment for Example 1, no etching was performed. The specific steps are as follows: Step 1: Place a 4.5 μm thick polypropylene film in a silver deposition solution and deposit it for 14 min to obtain a silver-coated polypropylene film. Step 2: Electroplating copper onto the surface of the silver-coated polypropylene film. After the copper layer on the surface has thickened to 1 μm, wash with water and dry to obtain the functional current collector. The silver deposition solution includes: 28 g / L silver nitrate, 56 g / L ascorbic acid, and 2 g / L gelatin. Detection experiment The peel force of the current collectors prepared in Examples 1-7 and Comparative Examples 1-3 was tested using an electronic peel tester. The specific data are as follows:
[0013] Conclusion: Based on the above data, the radiation flux in Examples 1-5 is 1000 W / m². 2 Example 3, with an etching time of 5 minutes, exhibits extremely high peel strength compared to the other groups. Examples 6 and 7, based on Example 1, involve pretreatment of the polypropylene film and grafting of active groups to improve the adhesion of the functional current collector. Comparative Example 1, which does not undergo ultraviolet radiation during silver deposition, has a significant impact on peel strength. Comparative Example 2, without silver plating, has a peel resistance far lower than that of the present invention, which uses silver plating followed by copper plating. Comparative Example 3, without etching, exhibits good interlayer adhesion compared to Comparative Example 1, as etching provides better interlayer adhesion.
[0014] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for producing a high-bonding functional current collector, characterized in that, The method for producing functional current collectors includes the following steps: Step 1: After etching, alkali washing and drying, the polypropylene film is placed in a silver deposition solution for ultraviolet radiation deposition to obtain a silver-coated polypropylene film. Step 2: Immerse the silver-coated polypropylene film prepared in Step 1 into the electroplating solution. After the copper plating layer on the surface thickens to 1 μm, wash with water and dry to obtain the functional current collector.
2. The method for producing a high-bonding functional current collector according to claim 1, characterized in that, In step 1, the etching process uses 6.5% K2Cr2O7 and 93.5% H2SO4 by mass, and the etching process lasts for 3-5 minutes.
3. The method for producing a high-bonding functional current collector according to claim 1, characterized in that, In step 1, the silver deposition solution consists of silver nitrate, ascorbic acid, gelatin, and deionized water; the ratio of ascorbic acid to silver nitrate is 2:1, the concentration of silver nitrate is 25-30 g / L, and the concentration of gelatin is 1-3 g / L.
4. The method for producing a high-bonding functional current collector according to claim 1, characterized in that, The radiant flux emitted in step 1 is 900-1100 W / m. 2 The deposition time is 10-15 minutes.
5. The method for producing a high-bonding functional current collector according to claim 1, characterized in that, The method for producing the functional current collector also includes a pretreatment of the polypropylene membrane after alkali washing and drying, specifically including the following steps: Step S1: Place the polypropylene membrane after alkaline washing and drying in step 1 into an acrylic grafting solution at a solid-liquid ratio of 1:(40-60). After vacuuming, nitrogen gas is introduced every 10 minutes. After ultraviolet irradiation, the membrane is washed with alcohol and water alternately 2-3 times to obtain a carboxyl functionalized polypropylene membrane. Step S2: Under a protective atmosphere, a mixed solution of diethylenetriamine and methanol is slowly added dropwise to methyl acrylate. After reacting for 24 hours, the mixture is vacuum filtered at 65℃-70℃ for 1 hour. The temperature is then increased by 10℃ for 1 hour each time, and the mixture is kept at 140℃ for 4 hours to obtain a hyperbranched polymer. Water is added and the mixture is stirred to obtain an aqueous solution of the hyperbranched polymer. Step S3: Immerse the carboxyl-functionalized polypropylene membrane prepared in S1 into the aqueous solution of the hyperbranched polymer prepared in S2, with a solid-liquid ratio of 1:(50-60). Add EDC hydrochloride and N-hydroxysuccinimide, stir and react for 1-3 hours, wash with alcohol and water alternately, and then dry.
6. The method for producing a high-bonding functional current collector according to claim 5, characterized in that, The preparation steps of the acrylic acid grafting solution in step S1 include: ultrasonicating an aqueous solution of ferrous ammonium sulfate and a benzophenone alcohol solution for 3 min-5 min, adding acrylic acid, and then ultrasonicating for 1 min-2 min to obtain the solution; wherein the mass fraction of acrylic acid in the acrylic acid grafting solution is 10%-25%; the ultraviolet irradiation temperature is 60℃-80℃, and the irradiation time is 30 min-40 min.
7. The method for producing a high-bonding functional current collector according to claim 5, characterized in that, In step S2, the molar ratio of diethylenetriamine to methyl acrylate is 1:
1.
8. A functional current collector, characterized in that, It is prepared by the method for producing a high-bonding functional current collector according to any one of claims 1-7.
9. The application of the functional current collector as described in claim 8 in the battery industry.