Composite aluminum foil and preparation method thereof

Abstract

The present invention relates to a composite aluminum foil and a preparation method thereof. The method for preparing the composite aluminum foil comprises: polymer substrate pretreatment: providing a polymer substrate, and performing surface modification on at least one surface of the polymer substrate by corona treatment or chemical etching solution to obtain a surface-modified polymer substrate; conductive layer preparation: covering at least one surface of the surface-modified polymer substrate with a conductive material by chemical plating or coating or vapor deposition, and performing heating and pressurization treatment to obtain a polymer substrate covered with a conductive layer; aluminum layer plating: placing the polymer substrate covered with a conductive layer in an ionic liquid, depositing an aluminum layer on the surface of the conductive layer by electroplating, and performing heating and pressurization treatment to obtain a composite aluminum foil; post-plating cleaning: placing the composite aluminum foil in an organic cleaning solution for cleaning. The preparation method of the composite aluminum foil of the present invention has the advantages of high yield and high production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of composite current collector production, in particular to a composite aluminum foil and a preparation method thereof, and more particularly to a method for preparing the composite aluminum foil based on aluminum electroplating technology and the composite aluminum foil prepared by the method. Background Art

[0002] Composite aluminum foil current collector has great research and application potential in the field of lithium-ion batteries due to its significant advantages in improving the safety, energy density and cycle life of lithium-ion batteries. At present, its main preparation method is to use physical vapor deposition technology to deposit a certain thickness of aluminum layer on the surface of the polymer substrate, so that the composite aluminum foil meets the standards required for the positive electrode current collector of the battery.

[0003] Compared with physical vapor deposition technology, the composite aluminum foil preparation technology based on molten salt electroplating process has obvious advantages in improving production efficiency, reducing production costs and ensuring product quality. The preparation method of composite aluminum foil based on electroplating technology involves a multi-layer structure including an organic substrate, a conductive layer and an electroplated aluminum layer. The interfacial bonding force between the layers is crucial to the final service performance and life of the composite aluminum foil. However, based on the conventional electroplating process, the surface aluminum coating often falls off locally and the thickness is uneven, which seriously affects the yield and production efficiency of the composite aluminum foil.

[0004] In summary, with regard to the preparation technology of composite aluminum foil based on electroplating technology, it is urgent to develop a method to improve the interlayer bonding strength of composite aluminum foil. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for preparing a composite aluminum foil and a composite aluminum foil prepared by the method, so as to solve the problem in the prior art that the aluminum coating falls off and the thickness is uneven, thereby seriously affecting the yield and production efficiency of the composite aluminum foil.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present disclosure, a method for preparing a composite aluminum foil is provided, which comprises the following steps: Step S1: polymer substrate pretreatment: providing a polymer substrate, and performing surface modification on at least one surface of the polymer substrate by corona treatment or chemical etching solution to obtain a surface-modified polymer substrate; Step S2: conductive layer preparation: covering at least one surface of the surface-modified polymer substrate with a conductive material by chemical plating or coating or vapor deposition, and performing heating and pressurization treatment to obtain a polymer substrate covered with a conductive layer; Step S3: aluminum layer plating: placing the polymer substrate covered with a conductive layer in an ionic liquid, depositing an aluminum layer on the surface of the conductive layer away from the polymer substrate by electroplating, and performing heating and pressurization treatment to obtain a composite aluminum foil; Step S4: post-plating cleaning: placing the composite aluminum foil in an organic cleaning solution for cleaning.

[0007] Further, in step S1, the polymer substrate is selected from one of polyethylene terephthalate, polypropylene, polyethylene, polyvinyl chloride, polytetrafluoroethylene, polyamide, polyimide, polyoxymethylene, poly(p-phenylene sulfide), poly(p-phenylene ether) and polyethylene glycol.

[0008] Further, in step S1, the chemical etching solution is an aqueous solution containing one or more of sulfuric acid, potassium permanganate, potassium dichromate, chloric acid, sodium hydroxide, nitric acid and hydrogen peroxide.

[0009] Further, in step S2, the conductive material is selected from one or more of carbon, copper, aluminum, nickel, silver, gold and graphene.

[0010] Further, in step S3, electroplating is performed under a gradually increasing voltage, wherein the voltage is controlled to increase from an initial value in the range of 0 to 5 V to 1 to 20 V at a rate of 1 to 20 V / min.

[0011] Further, in step S3, the ionic liquid comprises anhydrous aluminum chloride and an organic salt, and the molar ratio of anhydrous aluminum chloride to the organic salt is 1 to 3:1, wherein the organic salt is selected from one of brominated ethylpyridine, n-butylpyridinium chloride, 1-ethyl-3-methylimidazole chloride, urea and acetamide.

[0012] Furthermore, in the heating and pressurizing treatment of step S2 and step S3, the heating range is 40 to 60° C., the pressurizing range is 0.3 to 10 MPa, and the treatment time is 0.5 to 20 min.

[0013] Further, in step S4, the organic cleaning liquid is one or more selected from ethyl acetate, acetonitrile, ethanol and ethylene glycol.

[0014] Furthermore, the method is carried out continuously or discontinuously.

[0015] According to another aspect of the present disclosure, a composite aluminum foil is provided, which is prepared by any one of the above methods.

[0016] As described above, compared with physical vapor deposition technology, the composite aluminum foil preparation technology based on molten salt electroplating process has obvious advantages in improving production efficiency, reducing production costs and ensuring product quality. According to the technical solution of the present disclosure, a method for preparing a composite aluminum foil is provided, by pre-treating the polymer substrate with corona treatment or chemical etching solution before the subsequent conductive layer and aluminum layer are implemented, so as to achieve a roughening effect on the surface of the polymer substrate, and generate hydrophilic groups on the surface of the polymer substrate, thereby improving the interfacial bonding between the polymer substrate and the subsequent conductive layer and aluminum layer. In addition, by heating and pressurizing after the preparation of the conductive layer and the aluminum layer, the density and interlayer bonding of each layer are improved. Moreover, by introducing an organic cleaning solution to clean the composite aluminum foil, it is possible to prevent the ionic liquid residue from corroding the composite aluminum foil, while avoiding the damage to the aluminum layer due to reactions such as heat release and bubbling generation during the cleaning process. Therefore, the technical solution of the present disclosure can significantly improve the interlayer bonding force and thickness uniformity, thereby improving the yield rate and production efficiency of the composite aluminum foil. DETAILED DESCRIPTION

[0017] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present disclosure will be described in detail below in conjunction with the embodiments.

[0018] In view of the deficiencies in the prior art mentioned in the background technology, a specific embodiment of the present disclosure provides a method for preparing a composite aluminum foil, which includes the following steps: Step S1: Polymer substrate pretreatment: providing a polymer substrate, and surface-modifying at least one surface of the polymer substrate by corona treatment or chemical etching solution to obtain a surface-modified polymer substrate; Step S2: Conductive layer preparation: covering at least one surface of the surface-modified polymer substrate with a conductive material by chemical plating or coating or vapor deposition, and performing a heating and pressurizing treatment to obtain a polymer substrate covered with a conductive layer; Step S3: Aluminum layer plating: placing the polymer substrate covered with a conductive layer in an ionic liquid, depositing an aluminum layer on the surface of the conductive layer away from the polymer substrate by electroplating, and performing a heating and pressurizing treatment to obtain a composite aluminum foil; Step S4: Post-plating cleaning: placing the composite aluminum foil in an organic cleaning solution for cleaning.

[0019] From the perspective of economy and cleaning cleanliness, the cleaning time is preferably 30 to 300 seconds. For example, the cleaning time can be 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 110 seconds, 120 seconds, 130 seconds, 140 seconds, 150 seconds, 160 seconds, 170 seconds, 180 seconds, 190 seconds, 200 seconds, 210 seconds, 220 seconds, 230 seconds, 240 seconds, 250 seconds, 260 seconds, 270 seconds, 280 seconds, 290 seconds or 300 seconds.

[0020] The method for preparing a composite aluminum foil disclosed in the present invention pre-treats the polymer substrate with a corona treatment or a chemical etching solution before the subsequent conductive layer and the electroplating layer are implemented, thereby achieving a roughening effect on the surface of the polymer substrate, and generating hydrophilic groups on the surface of the polymer substrate, thereby improving the interfacial bonding between the polymer substrate and the subsequent conductive layer and the aluminum layer. In addition, by performing a heating and pressurizing treatment after the preparation of the conductive layer and the aluminum layer, the density and interlayer bonding of each layer are improved. Moreover, by introducing an organic cleaning solution to clean the composite aluminum foil, it is possible to prevent the ionic liquid residue from corroding the composite aluminum foil, while avoiding damage to the aluminum layer due to reactions such as heat release and bubbling during the cleaning process. Therefore, the technical solution disclosed in the present invention can significantly improve the interlayer bonding and thickness uniformity, thereby improving the yield rate and production efficiency of the composite aluminum foil.

[0021] In some embodiments of the present invention, in the step of pre-treating the polymer substrate, the temperature of the pre-treatment of the polymer substrate is 18-60°C, and the treatment time is 10-200s. For example, the treatment temperature is 18°C, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, etc., and the treatment time is 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s, 180s, 190s, 200s, etc. The treatment temperature and treatment time of the polymer substrate within the scope of the present disclosure can help accelerate the speed of surface pretreatment of the polymer substrate, facilitate the roughening reaction of the polymer substrate surface and the formation of hydrophilic groups, thereby further improving the interface bonding strength between the organic polymer substrate and the subsequently plated or coated conductive layer and aluminum layer, and improving the yield rate.

[0022] In some embodiments of the present invention, in the step of preparing the conductive layer, the temperature of covering the conductive layer is 18-60°C, and the covering time is 40-300s. For example, the covering temperature is 18°C, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, etc., and the covering time is 40s, 50s, 60s, 70s, 80s, 90s, 100s, 150s, 200s, 250s, 260s, 270s, 280s, 290s, 300s, etc. The temperature and covering time of the conductive layer are within the scope of the present disclosure, which can help to further accelerate the covering rate of the conductive layer, thereby further improving the yield production efficiency.

[0023] In some embodiments of the present invention, in the step of aluminum layer plating, the temperature of aluminum layer plating is 18-60°C, and the plating time is 5-30min. For example, the plating temperature is 18°C, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, etc., and the plating time is 5min, 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min, 19min, 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min, 30min, etc. The temperature and plating time of the aluminum layer electroplating are within the scope of the present disclosure, which can further improve the interfacial bonding strength between the aluminum layer and the front coating, and can further help to accelerate the speed of aluminum layer plating, thereby further improving production efficiency compared to the physical vapor deposition process and further reducing high-temperature damage to the polymer substrate.

[0024] In step S2, the chemical plating solution used in the chemical plating of the conductive layer may include chloroauric acid, sodium carbonate and formaldehyde, or may include nickel sulfate, sodium hypophosphite, trisodium citrate and sodium acetate. For example, the chemical plating solution is prepared from chloroauric acid, sodium carbonate, formaldehyde and deionized water.

[0025] In a further embodiment of the present invention, in step S1, the polymer substrate is selected from one of polyethylene terephthalate, polypropylene, polyethylene, polyvinyl chloride, polytetrafluoroethylene, polyamide, polyimide, polyoxymethylene, poly(p-phenylene sulfide), poly(p-phenylene ether) and polyethylene glycol.

[0026] The above are merely examples of polymer substrates that can be used in the present application, but the polymer substrates are not limited thereto.

[0027] In a further embodiment of the present invention, in step S1, the chemical etching solution is an aqueous solution containing one or more of sulfuric acid, potassium permanganate, potassium dichromate, chloric acid, sodium hydroxide, nitric acid and hydrogen peroxide. The use of the above chemical etching solution is conducive to further improving the roughening and activation efficiency of the polymer substrate surface, and helps to further improve the formation of hydrophilic groups on the polymer substrate surface, thereby further improving the interface bonding force between the polymer substrate and the subsequent conductive layer and aluminum layer, and further improving the yield and production efficiency.

[0028] In a further embodiment of the present invention, in step S2, the conductive material is selected from one or more of carbon, copper, aluminum, nickel, silver, gold and graphene. Graphene is such as graphene conductive glue. The conductive material within this range can better impart good conductivity to the polymer substrate, thereby providing better conditions for subsequent metal electroplating.

[0029] In a further embodiment of the present invention, in step S3, electroplating is performed at a gradually increasing voltage, wherein the voltage is controlled to increase from an initial value in the range of 0 to 5 V to 1 to 20 V at a rate of 1 to 20 V / min. Preferably, the voltage increase rate is controlled at 3 to 20 V / min, more preferably 5 to 15 V / min. During the electroplating of the aluminum layer, by applying the voltage in a gradually increasing manner, the interlayer bonding force of the composite aluminum foil can be further improved, thereby further improving the yield rate of the composite aluminum foil.

[0030] In a further embodiment of the present invention, in step S3, the ionic liquid comprises anhydrous aluminum chloride and an organic salt and the molar ratio of anhydrous aluminum chloride to the organic salt is 1 to 3:1, wherein the organic salt is selected from one of brominated ethylpyridine, n-butylpyridinium chloride, 1-ethyl-3-methylimidazole chloride, urea and acetamide.

[0031] For example, the molar ratio of anhydrous aluminum chloride to the organic salt in the ionic liquid is 1-2.5:1, 1-2:1, more specifically 1:1, 1.5:1, 2:1, 2.5:1 or 3:1.

[0032] The present application uses an ionic liquid containing anhydrous aluminum chloride and an organic salt in a molar ratio of 1 to 3:1, which is beneficial to further improve the bonding force between the electroplated aluminum layer and the polymer substrate, further accelerate the deposition speed, thereby more effectively improving production efficiency and facilitating large-scale production.

[0033] In a further embodiment of the present invention, in the heating and pressurizing treatment of step S2 and step S3, the heating range is 40-60°C, the pressurizing range is 0.3-10MPa, and the treatment time is 0.5-20min. By performing the heating and pressurizing treatment of step S2 and step S3 within the above heating range, pressurizing range and treatment time range, the density of each layer and the interlayer bonding can be more significantly improved, thereby improving the yield rate and production efficiency of the composite aluminum foil.

[0034] The heating range here refers to the target temperature range of the heating treatment, and the pressurization range refers to the target pressure range of the pressurization treatment. The heating and pressurization treatment is intended to control the obtained aluminum layer and polymer substrate within the above-mentioned temperature and pressure range. Specifically, the heating range is 40 to 60°C, preferably 40 to 55°C, and more preferably 40 to 50°C; the pressurization range is 0.3 to 10MPa, preferably 0.6 to 8MPa, and more preferably 1 to 5MPa; the treatment time is 0.5 to 20min, preferably 1 to 20min, and more preferably 5-20min.

[0035] In a further embodiment of the present invention, in step S4, the organic cleaning liquid is one or more selected from ethyl acetate, acetonitrile, ethanol and ethylene glycol. By using the above cleaning liquid to clean the composite aluminum foil, it is possible to more effectively prevent the ionic liquid residue from corroding the composite aluminum foil, and better avoid the damage to the aluminum layer due to reactions such as heat release and bubbling during the cleaning process.

[0036] In a further embodiment of the present invention, the method is carried out continuously or discontinuously. Those skilled in the art can choose to carry out the method continuously or discontinuously as needed.

[0037] Preferably, the method is carried out continuously. More preferably, step S1, step S2 and step S3 are carried out continuously in a roll-to-roll manner, and the winding speeds of step S1, step S2 and step S3 are each in the range of 1-50 m / min and the winding speeds of the three are the same.

[0038] In some preferred embodiments of the present invention, in the composite aluminum foil, the thickness D1 of the polymer substrate satisfies: 1 μm≤D1≤20 μm; the thickness D2 of the conductive layer satisfies: 10 nm≤D2≤1000 nm; and the thickness D3 of the aluminum layer satisfies: 1 μm≤D3≤10 μm.

[0039] The polymer substrate pretreatment step, the conductive layer preparation step and the aluminum layer plating step of the present invention are carried out in a roll-to-roll manner, so that the polymer substrate pretreatment, the conductive layer preparation and the aluminum layer plating can be carried out continuously. The roll-to-roll production method can save the interruption, shifting, placement and waiting process between each link, and can improve production efficiency while avoiding problems such as surface oxidation, deactivation and increased internal stress of the material caused by long-term placement, thereby further improving the product yield, improving production efficiency, and facilitating large-scale production.

[0040] According to another embodiment of the present invention, a composite aluminum foil prepared by the above method is provided.

[0041] The method for preparing the composite aluminum foil disclosed in the present application comprises pre-treating the polymer substrate with corona treatment or chemical etching solution before the subsequent conductive layer and aluminum layer are implemented, heating and pressurizing the material after the preparation of the conductive layer and the aluminum layer is completed, and cleaning the composite aluminum foil by introducing an organic cleaning solution, so that the composite aluminum foil prepared by the method of the present application has high interlayer bonding strength, uniform thickness, and high yield.

[0042] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0043] Example 1

[0044] (1) Pretreatment of polymer substrate: Polyamide was used as the polymer substrate, and the surface of the polymer substrate was subjected to corona treatment at a temperature of 35° C. to obtain a surface-modified polymer substrate.

[0045] (2) Preparation of conductive layer: Graphene conductive adhesive was coated on the surface of the surface-modified polymer substrate at a temperature of 35° C. After coating with graphene conductive adhesive, the polymer substrate covered with the conductive layer was subjected to heating and pressurization treatment at a heating temperature of 50° C., an external pressure of 1.6 MPa, and a heating and pressurization time of 10 min.

[0046] (3) Aluminum electroplating: The polymer substrate covered with the conductive layer is used as the cathode and the aluminum plate is used as the anode. Aluminum electroplating is performed at a temperature of 35°C for 6 minutes. The electroplating solution is an ionic liquid, which is prepared from anhydrous aluminum chloride and acetamide. The molar ratio of anhydrous aluminum chloride to acetamide used in the preparation is 1.5:1. Electroplating is performed at a gradually increasing voltage, and the voltage is controlled to increase from 5V to 15V at a rate of 5V / min. After electroplating, heating and pressurization treatment is performed, the heating temperature is 50°C, the external pressure is 1.6MPa, and the heating and pressurization time is 10 minutes to obtain a composite aluminum foil.

[0047] (4) Post-plating cleaning: The composite aluminum foil was placed in flowing ethyl acetate for cleaning at 35°C for 40 seconds.

[0048] Example 2

[0049] (1) Pretreatment of polymer substrate: Polyethylene terephthalate was used as the polymer substrate. The polymer substrate was immersed in a chemical etching solution at a temperature of 60° C. for 60 seconds to roughen and activate the surface of the polymer substrate, thereby obtaining a surface-modified polymer substrate. The chemical etching solution was prepared from potassium permanganate, sulfuric acid and deionized water. In the prepared chemical etching solution, the concentration of potassium permanganate was 100 g / L and the concentration of sulfuric acid was 200 g / L.

[0050] (2) Preparation of conductive layer: Place the surface-modified polymer substrate in a chemical plating solution at a temperature of 60°C and soak it in the chemical plating solution for 120 seconds. The chemical plating solution is prepared from chloroauric acid, sodium carbonate, formaldehyde and deionized water. The concentration of chloroauric acid in the prepared chemical plating solution is 33g / L, the concentration of sodium carbonate is 95g / L, and the concentration of formaldehyde is 60mL / L. A gold layer is deposited on the upper and lower surfaces of the surface-modified polymer substrate. Then, a heating and pressurizing treatment is performed, with a heating temperature of 40°C, an external pressure of 0.6MPa, and a heating and pressurizing time of 20min to obtain a polymer substrate covered with a conductive layer.

[0051] (3) Aluminum electroplating: The polymer substrate covered with the conductive layer is used as the cathode and the aluminum plate is used as the anode. Aluminum electroplating is performed at a temperature of 60°C for 10 minutes. The electroplating solution is an ionic liquid, which is prepared from anhydrous aluminum chloride and 1-ethyl-3-methylimidazole chloride. The molar ratio of anhydrous aluminum chloride to 1-ethyl-3-methylimidazole chloride used in the preparation is 2:1. Electroplating is performed at a gradually increasing voltage, and the voltage is controlled to increase from 0V to 20V at a rate of 20V / min. After electroplating, heating and pressurization treatment is performed, the heating temperature is 40°C, the external pressure is 0.6MPa, and the heating and pressurization time is 20min to obtain a composite aluminum foil.

[0052] (4) Post-plating cleaning: The composite aluminum foil was placed in flowing acetonitrile for cleaning at 60°C for 60 seconds.

[0053] Example 3

[0054] (1) Pretreatment of polymer substrate: Polyimide is used as the polymer substrate. The polymer substrate is immersed in a chemical etching solution at a temperature of 20° C. for 200 seconds to roughen and activate the surface of the polymer substrate, thereby obtaining a surface-modified polymer substrate. The chemical etching solution is prepared from sodium hydroxide and deionized water. In the prepared chemical etching solution, the concentration of sodium hydroxide is 50 g / L.

[0055] (2) Preparation of the conductive layer: A layer of aluminum was vapor deposited (vapor-deposited) on the surface of the surface-modified polymer substrate at a temperature of 20° C. Then, the polymer substrate covered with the conductive layer was subjected to a heating and pressurizing treatment at a heating temperature of 60° C., an external pressure of 10 MPa, and a heating and pressurizing time of 5 min.

[0056] (3) Aluminum electroplating: The polymer substrate covered with the conductive layer is used as the cathode and the aluminum plate is used as the anode. Aluminum electroplating is performed at a temperature of 20°C for 30 minutes. The electroplating solution is an ionic liquid, which is prepared from anhydrous aluminum chloride and bromoethylpyridine. The molar ratio of anhydrous aluminum chloride to bromoethylpyridine used in the preparation is 2.5:1. Electroplating is performed at a gradually increasing voltage, and the voltage is controlled to increase from 5V to 15V at a rate of 1V / min. After electroplating, heating and pressurization treatment is performed, the heating temperature is 60°C, the external pressure is 10MPa, and the heating and pressurization time is 5min to obtain a composite aluminum foil.

[0057] (4) Post-plating cleaning: The composite aluminum foil was placed in flowing ethylene glycol for cleaning at 20°C for 300 seconds.

[0058] Example 4

[0059] The composite aluminum foil was prepared in the same manner as in Example 1, except that a constant voltage of 20 V was applied during aluminum electroplating instead of being applied in a gradually increasing manner.

[0060] Comparative Example 1

[0061] The composite aluminum foil was prepared in the same manner as in Example 1, except that the polymer substrate pretreatment step was not performed.

[0062] Comparative Example 2

[0063] The composite aluminum foil was prepared in the same manner as in Example 1, except that the heating and pressurizing treatment after the conductive layer was implemented was not performed.

[0064] Comparative Example 3

[0065] The composite aluminum foil was prepared in the same manner as in Example 1, except that the heating and pressurizing treatment after aluminum electroplating was not performed.

[0066] Comparative Example 4

[0067] The composite aluminum foil was prepared in the same manner as in Example 1, except that deionized water was used to wash the composite aluminum foil.

[0068] Performance Testing

[0069] Determination of surface resistance

[0070] The surface resistance was measured using a four-probe resistance meter at a temperature of 25°C.

[0071] Binding strength assay

[0072] The bonding strength was measured using a universal tensile testing machine. The composite aluminum foil sample was cut into a rectangle with a width of 60 mm and a length of 150 mm. The sample was fixed to the universal tensile testing machine using 3M tape. The peeling speed was 10 mm min. -1 , the test temperature is 25℃.

[0073] Roughness Rz measurement

[0074] The Rz value of the composite aluminum foil surface was measured using a roughness meter.

[0075] Table 1

[0076]

[0077] From the above results, it can be seen that based on Examples 1-4 of the method for preparing a composite aluminum foil of the present invention, the surface square resistance of the composite aluminum foil obtained by the four steps of polymer substrate pretreatment, conductive layer preparation, aluminum layer plating, and post-plating cleaning is less than 56.5Ω·□ -1 (Ω·sq -1 ), the bonding strength between the aluminum layer and the polymer substrate is higher than 2.4kg / mm 2 Compared with Comparative Examples 1-4, it can be seen that pre-treating the substrate, adding a heating and pressurizing process in the preparation of the conductive layer and the aluminum layer plating, optimizing the cleaning process, and increasing the pressure in the aluminum layer plating are all conducive to significantly improving the interlayer bonding strength of the composite aluminum foil.

[0078] The above description only relates to specific embodiments of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for preparing a composite aluminum foil, characterized in that: The following steps are involved: Step S1: pretreatment of polymer substrate: providing a polymer substrate, and performing surface modification on at least one surface of the polymer substrate by corona treatment or chemical etching solution to obtain a surface-modified polymer substrate; Step S2: preparing a conductive layer: covering the at least one surface of the surface-modified polymer substrate with a conductive material by chemical plating, coating or vapor deposition, and performing a heating and pressurizing treatment to obtain a polymer substrate covered with a conductive layer; Step S3: aluminum layer plating: placing the polymer substrate covered with the conductive layer in an ionic liquid, depositing an aluminum layer on the surface of the conductive layer away from the polymer substrate by electroplating, and performing heating and pressurization treatment to obtain the composite aluminum foil; Step S4: Post-plating cleaning: placing the composite aluminum foil in an organic cleaning solution for cleaning.

2. The method according to claim 1, characterized in that In the step S1, the polymer substrate is selected from one of polyethylene terephthalate, polypropylene, polyethylene, polyvinyl chloride, polytetrafluoroethylene, polyamide, polyimide, polyoxymethylene, poly(p-phenylene sulfide), poly(p-phenylene ether) and polyethylene glycol.

3. The method according to claim 1 or 2, characterized in that: In the step S1, the chemical etching solution is an aqueous solution containing one or more of sulfuric acid, potassium permanganate, potassium dichromate, chloric acid, sodium hydroxide, nitric acid and hydrogen peroxide.

4. The method according to claim 1 or 2, characterized in that: In step S2, the conductive material is selected from one or more of carbon, copper, aluminum, nickel, silver, gold and graphene.

5. The method according to claim 1 or 2, characterized in that: In the step S3, the electroplating is performed under a gradually increasing voltage, wherein the voltage is controlled to increase from an initial value in the range of 0 to 5 V to 1 to 20 V at a rate of 1 to 20 V / min.

6. The method according to claim 1 or 2, characterized in that: In step S3, the ionic liquid comprises anhydrous aluminum chloride and an organic salt, and the molar ratio of anhydrous aluminum chloride to the organic salt is 1 to 3:1, wherein the organic salt is selected from one of brominated ethyl pyridine, n-butyl pyridine chloride, 1-ethyl-3-methyl imidazole chloride, urea and acetamide.

7. The method according to claim 1 or 2, characterized in that: In the heating and pressurizing treatment of step S2 and step S3, the heating range is 40 to 60° C., the pressurizing range is 0.3 to 10 MPa, and the treatment time is 0.5 to 20 min.

8. The method according to claim 1 or 2, characterized in that: In step S4, the organic cleaning solution is one or more selected from ethyl acetate, acetonitrile, ethanol and ethylene glycol.

9. The method according to claim 1 or 2, characterized in that: The method is carried out continuously or discontinuously.

10. A composite aluminum foil, characterized in that: The composite aluminum foil is prepared by the method according to any one of claims 1 to 9.

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