Method for producing electrolytic copper foilTechnical Field
The invention relates to the technical field of materials, in particular to a method for manufacturing an electrolytic copper foil without a carrier.
Background
With the development of a highly information-oriented society, a mobile phone is rapidly popularized as a notebook computer product, and since people pay attention to environmental protection and energy conservation, the development of electric vehicles is receiving much attention, and a lithium ion battery is the most ideal energy source as a power source of the above products. The copper foil is used as a main material of a negative current collector of the lithium ion battery, and the development of the production technology and the quality of the performance directly influence the manufacturing process, the performance and the production cost of the lithium ion battery.
Currently, copper foil products are divided into two types, rolled copper foil and electrolytic copper foil. The rolled copper foil is formed by heating a thick copper plate to an annealing temperature, then rolling, and repeating annealing and rolling for multiple times to obtain the original foil meeting the thickness requirement. The surface of the raw foil is then treated according to the requirements of use. Compared with electrolytic copper foil, the rolled copper foil has higher yield strength and ductility, lower surface roughness and better compactness and elasticity. However, the rolled copper foil has a complex production process, a long flow, a high one-time investment and a high production cost. The electrolytic copper foil is prepared by using a copper sulfate solution as a raw material, electrolyzing in an electrolytic tank by using an insoluble material as an anode and a cathode roller with the bottom part immersed in a copper sulfate electrolyte and rotating at a constant speed as a cathode, and depositing copper in the solution on the surface of the cathode roller to form the copper foil, wherein the thickness of the copper foil is controlled by the cathode current density and the rotating speed of the cathode roller. After the copper foil rotates out of the liquid level along with the roller, the copper foil is continuously stripped from the cathode roller, and the original foil is prepared through washing, drying and coiling. The surface of the raw foil is then treated according to the requirements of use. With the development of battery production technology and the improvement of the performance of ultra-thin electrolytic copper foil, lithium battery manufacturers generally adopt electrolytic copper foil to manufacture the negative current collector of a lithium battery, especially the ultra-thin electrolytic copper foil for the negative current collector of the lithium battery, and the ultra-thin electrolytic copper foil is widely applied due to the characteristics of higher energy density, good charge-discharge cycle characteristic and light weight. However, as these electronic products are miniaturized, thin, and have a large capacity, copper foil, which is a main material for manufacturing lithium batteries, is also required to be higher. The copper foil for the lithium ion battery cathode current collector has the advantages that the quality of the copper foil on the lithium ion battery is reduced, the cost of the copper foil raw material is reduced, and meanwhile, high energy density is provided, so that the copper foil becomes another requirement for the copper foil for the lithium ion battery cathode current collector in the future. The most effective way is to reduce the copper foil thickness.
At present, the thickness of the rolled copper foil can be reduced to 6 microns, the yield is more than 90%, but the production process is complex, the flow is long, the one-time investment is high, and the production cost is high. The electrolytic copper foil has simple process, small equipment investment and lower product cost, but the thickness of the main stream electrolytic copper foil is 8-10 mu m, which is not more and more suitable for the development requirement of the lithium ion battery, if the thickness is reduced to 6 mu m, the yield can be greatly reduced to less than 50 percent, and the production cost of the electrolytic copper foil is greatly improved, so that the research and development of a novel process for preparing the ultrathin electronic copper foil for the lithium ion battery cathode current collector, which has simple process, small equipment investment, high yield and low product cost, is necessary.
Disclosure of Invention
The invention aims to provide a manufacturing method of an electrolytic copper foil, the electrolytic copper foil obtained by the manufacturing method has a small thickness of only 4-50 mu m, can meet the requirement of an ultrathin negative current collector, and has simple manufacturing process and low cost.
In order to achieve the above object, the present invention provides a method for manufacturing an electrolytic copper foil, comprising the steps of:
(1) Coarsening the base material and then electroplating the upper surface of the base material to form a copper layer;
(2) Washing with water, drying at 80-150 deg.C for 2-10 min to strip the copper layer from the substrate to form an electrolytic copper foil,
the base material comprises an aluminum foil layer, a high-temperature-resistant resin adhesive layer and a matrix layer which are sequentially stacked from top to bottom.
Compared with the traditional method, in the method for manufacturing the electrolytic copper foil, the copper layer is formed on the upper surface of the base material, and the base material comprises an aluminum foil layer, a high-temperature-resistant resin glue layer and a base layer which are sequentially laminated from top to bottom, namely a four-layer structure of the copper layer, the aluminum foil layer, the high-temperature-resistant resin glue layer and the base layer is formed, when the base material is dried for 2-10 min at 80-150 ℃, the high-temperature-resistant resin glue layer still can adhere the aluminum foil layer to the base layer, the aluminum foil layer and the copper layer are easy to shrink by heating, the high-temperature-resistant resin glue layer has thicker adhesion force on the aluminum foil layer, so that the aluminum foil layer is deformed towards the base layer, the shrinkage rates of the aluminum foil layer and the copper layer are different, and the aluminum foil layer and the copper layer are easy to be peeled and separated after the drying, so that the ultrathin electrolytic copper foil is manufactured. The manufacturing method carries out stripping through different shrinkage rates of the aluminum foil and the copper layer when being heated, so the thickness of the copper layer can be set according to actual requirements, and the thinner the copper layer is, the easier the copper layer is to be stripped when being heated and shrunk.
Preferably, the thickness of the copper layer is 4-50 μm, and the thickness of the copper layer can be set to be less than 8 μm, so that the requirement of an ultrathin negative current collector is met, and meanwhile, the thickness of the copper layer can also be set to be more than 10 μm so as to be used as a copper foil of a copper-clad plate.
Preferably, the electroplating adopts an electroplating solution containing copper sulfate and an additive, the copper content in the electroplating solution is 40-110 g/L, the acid content in the electroplating solution is 30-130 g/L, and the electroplating condition is that the electroplating is carried out for 10-30 seconds by adopting the current density of 1-15 ASD. Or, the electroplating can also adopt an electroplating solution containing copper pyrophosphate and an additive, wherein the copper content in the electroplating solution is 20-50 g/L, the total pyrophosphate ion content is 140-425 g/L, and the electroplating is carried out for 10-40 min under the condition of adopting the current density of 1-4A/d square meter.
Preferably, the roughening is carried out by immersing the substrate in an aqueous solution containing sulfuric acid for 20 to 60 seconds to etch the surface.
Preferably, the thickness of the aluminum foil layer is 25-100 μm, and the thickness of the high-temperature resistant resin glue layer is 3-20 μm.
Preferably, the heat distortion temperature of the high-temperature resistant resin adhesive layer is not less than 180 ℃, and the high-temperature resistant resin adhesive layer is obtained by curing reaction of at least one of cyanate ester resin, epoxy resin, bismaleimide and polyimide. The high-temperature-resistant resin adhesive layer is formed by homopolymerization or copolymerization of acid ester resin, epoxy resin, bismaleimide and polyimide under the action of an initiator, or copolymerization of the acid ester resin, the epoxy resin, the bismaleimide and the polyimide and other polymers, or is cured under the action of heating, ultraviolet light and UV light or by adding a curing agent for reaction so as to obtain the high-temperature-resistant resin adhesive layer.
Preferably, the material of the substrate layer is PET, PP or PI, preferably PET, and the thickness of the substrate layer is 25-75 μm.
Detailed Description
The manufacturing method of the electrolytic copper foil is different from the traditional mode of directly stripping the copper layer after electrolysis, the electrolytic copper foil is formed by stripping the copper layer from the aluminum foil layer through different shrinkage rates of the copper layer and the aluminum foil layer when being heated, and the copper layer can be arranged to be thinner before stripping, such as less than or equal to 8 mu m, so that the requirement of an ultrathin negative current collector can be met. It may comprise the steps of:
(1) Coarsening the base material and then electroplating the upper surface of the base material to form a copper layer;
(2) Washing with water, drying at 80-150 deg.C for 2-10 min to strip the copper layer from the substrate to form electrolytic copper foil,
the base material comprises an aluminum foil layer, a high-temperature-resistant resin adhesive layer and a matrix layer which are sequentially stacked from top to bottom.
Then, roughening treatment is carried out before electroplating, wherein roughening treatment is to soak the base material in an aqueous solution containing sulfuric acid for 20-60 seconds to corrode the surfaceForming micro-roughness structure. The electroplating adopts electroplating solution containing copper sulfate and additives, wherein the copper content in the electroplating solution is 40-110 g/L, the acid content is 30-130 g/L, and the additives can be brightening agents, leveling agents and the like. Specifically, the electroplating solution can be 75g/L copper sulfate, 180g/L sulfuric acid, 0.008g/L chloride ion, 0.01 g/L3-mercapto-1-propyl sodium sulfonate, 0.01g/L sodium polydithio dipropyl sulfonate and 0.02g/L polyethylene glycol aqueous solution, and of course, the invention can also adopt other electroplating methods for electroplating, for example, the electroplating process adopted by the copper electroplating layer is as follows: the plating solution comprises copper pyrophosphate and an additive, wherein the copper content in the plating solution is 20-50 g/L, the total pyrophosphate ion content is 140-425 g/L, and 1-4A/dm is adopted2 The current density of (2) is electroplated for 10-40 min. Furthermore, the electroplating condition is that the current density of 1-15 ASD is adopted for electroplating for 10-30 seconds. The thickness of the copper layer is 4 to 50 μm, preferably 4 to 8 μm, so that it satisfies the demand of an ultra-thin negative electrode collector. The thickness of the aluminum foil layer in the base material is 25-100 μm, and the thickness of the high-temperature resistant resin adhesive layer is 3-20 μm. The heat distortion temperature of the high-temperature resistant resin adhesive layer is more than or equal to 180 ℃, and the high-temperature resistant resin adhesive layer is obtained by curing at least one of cyanate ester resin, epoxy resin, bismaleimide and polyimide. The material of the substrate layer is PET, PP or PI, the thickness of the substrate layer is 25-75 μm, preferably PET. The washing in the step (2) can adopt three-stage washing, and the drying can be carried out in a drying oven.
The method for producing the electrolytic copper foil of the present invention will be described in detail with reference to specific examples.
Example 1
The base material is adopted and comprises a 50-micron aluminum foil layer, a 15-micron high-temperature-resistant resin adhesive layer and a 50-micron PET (polyethylene terephthalate) which are sequentially stacked from top to bottom, wherein the high-temperature-resistant resin adhesive layer is prepared by curing reaction of bisphenol S type epoxy resin and novolac epoxy resin under the action of an amine curing agent. The substrate was immersed in an aqueous solution containing sulfuric acid (30 g/L) for 40 seconds to be roughened, followed by three-stage washing with water. After washing, electroplating is carried out on the surface of the aluminum foil layer to form a copper layer with the thickness of 8 mu m, 75g/L of copper sulfate, 60g/L of sulfuric acid, 0.008g/L of chloride ions, 0.01g/L of 3-mercapto-1-propyl sodium sulfonate, 0.01g/L of sodium polydithio-dipropyl sulfonate and 0.02g/L of polyethylene glycol are adopted for electroplating, and the electroplating is carried out for 30 seconds by adopting the current density of 10 ASD.
And (3) after the electroplating is finished, three-stage water washing is adopted, and the aluminum foil layer and the copper layer are dried in a drying oven at 100 ℃ for 10min, so that the thermal shrinkage rates of the aluminum foil layer and the copper layer are different, the copper layer and the aluminum foil layer can be peeled to obtain the electrolytic copper foil, and the thickness of the obtained electrolytic copper foil is 8 mu m.
Example 2
The base material is adopted and comprises a 50-micron aluminum foil layer, a 15-micron high-temperature-resistant resin adhesive layer and a 50-micron PET (polyethylene terephthalate) which are sequentially stacked from top to bottom, wherein the high-temperature-resistant resin adhesive layer is prepared by curing reaction of bisphenol S type epoxy resin and novolac epoxy resin under the action of an amine curing agent. The substrate was immersed in an aqueous solution containing sulfuric acid (30 g/L) for 40 seconds to be roughened, followed by three-stage washing with water. After washing, electroplating is carried out on the surface of the aluminum foil layer to form a copper layer with the thickness of 6 mu m, the electroplating adopts an aqueous solution of 70g/L copper sulfate, 60g/L sulfuric acid, 0.008g/L chloride ion, 0.01 g/L3-mercapto-1-propyl sodium sulfonate, 0.01g/L sodium polydithio-dipropyl sulfonate and 0.02g/L polyethylene glycol, and the electroplating adopts a current density of 8ASD to electroplate for 20 seconds.
And (3) after the electroplating is finished, three-stage water washing is adopted, and the aluminum foil layer and the copper layer are dried in a drying oven at 120 ℃ for 8min, so that the thermal shrinkage rates of the aluminum foil layer and the copper layer are different, the copper layer and the aluminum foil layer can be peeled to obtain the electrolytic copper foil, and the thickness of the obtained electrolytic copper foil is 6 mu m.
Example 3
The base material is adopted and comprises a 50-micron aluminum foil layer, a 15-micron high-temperature-resistant resin adhesive layer and 75-micron PET which are sequentially stacked from top to bottom, wherein the high-temperature-resistant resin adhesive layer is prepared by curing reaction of bisphenol S type epoxy resin and novolac epoxy resin under the action of an amine curing agent. The substrate was immersed in an aqueous solution (30 g/L) containing sulfuric acid for 40 seconds to be roughened, followed by three-stage water washing. After washing, electroplating is carried out on the surface of the aluminum foil layer to form a copper layer with the thickness of 25 mu m, wherein the electroplating adopts an aqueous solution of 90g/L copper sulfate, 70g/L sulfuric acid, 0.008g/L chloride ion, 0.01 g/L3-mercapto-1-propyl sodium sulfonate, 0.01g/L sodium polydithio-dipropyl sulfonate and 0.02g/L polyethylene glycol, and the electroplating adopts the current density of 15ASD for 30 seconds.
And (3) after the electroplating is finished, three-stage water washing is adopted, and the aluminum foil layer and the copper layer are dried in a drying oven at 100 ℃ for 10min, so that the thermal shrinkage rates of the aluminum foil layer and the copper layer are different, the copper layer and the aluminum foil layer can be peeled to obtain the electrolytic copper foil, and the thickness of the obtained electrolytic copper foil is 25 mu m.
The thickness of the electrolytic copper foil manufactured by the manufacturing method can be set to be thinner, as shown in the embodiment 1 and the embodiment 2, the thickness of the electrolytic copper foil is less than or equal to 8 mu m, and the requirement of the ultrathin negative electrode current collector can be greatly met. Meanwhile, compared with the traditional mode that the electrolytic copper foil is obtained by stripping on the cathode roller after the electrolytic copper layer, the manufacturing method of the invention has the advantages of improving the yield and saving the cost.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.