CN218477240U

CN218477240U - Composite copper foil film

Info

Publication number: CN218477240U
Application number: CN202222425541.1U
Authority: CN
Inventors: 吴迪; 周振; 刘鸿纬; 赵星亮
Original assignee: Jiangsu Shuangxing Color Plastic New Materials Co Ltd
Current assignee: Jiangsu Shuangxing Color Plastic New Materials Co Ltd
Priority date: 2022-09-13
Filing date: 2022-09-13
Publication date: 2023-02-14
Anticipated expiration: 2032-09-13

Abstract

The utility model discloses a composite copper foil film, which consists of a substrate layer (1) and conducting layers (2) attached to the two sides of the substrate layer (1), wherein, the surfaces of the two sides of the substrate layer (1) are provided with a corona layer (10) with the thickness of 1-2 nm; a barrier layer (11) with the thickness of 2-3nm is formed on the outer side of the corona layer (10); the conducting layer (2) is formed on the outer side of the barrier layer (11), and the thickness of the substrate layer (1) is 6-10 microns. The utility model discloses a carry out surface corona treatment to the substrate layer, improved the adhesive force of barrier layer, the barrier layer forms the cladding of substrate layer completely cut off to form hydrophobic structure on the surface of substrate layer, moisture when avoiding forming the conducting layer absorbs and the release problem, and the conducting layer of formation can obtain excellent electrical property and adhesive force under the prerequisite of not destroying substrate layer surface structure.

Description

Composite copper foil film

Technical Field

The utility model relates to a can be used as lithium ion battery's negative pole mass flow body's compound copper foil membrane.

Background

The current collector in the lithium ion battery consists of a metal foil film for conducting electricity, and is mainly used for bearing electrode materials of a positive electrode and a negative electrode, and collecting current and conducting electrons at the same time. The common positive current collector adopts aluminum foil, and the common negative current collector adopts copper foil. The aluminum foil and the copper foil used as current collectors are mainly used for conduction and do not participate in active reactions, so that the thickness of the aluminum foil and the copper foil has been reduced to the strength limit and there has been no room for further thinning under the demand for increasing the energy density of the battery.

By referring to the composite metal thin film in the prior art, a composite metal thin film has appeared in which a non-metallic insulating material is used as a base material and conductive layers are formed on both sides thereof. In the preparation process of the composite metal foil in the prior art, the target needs to be evaporated into gas at high temperature and then attached to the surface of the nonmetallic substrate layer, and the higher the evaporation temperature of the target is, the more easily the substrate layer has defects such as fusing or scalding. Therefore, the prior art generally produces composite aluminum foil by means of evaporation, and the situation that composite copper foil is prepared by evaporation is rare because the evaporation temperature of copper is higher. The higher the evaporation temperature of the target material is, the higher the running speed of the substrate layer is required to be, so that the thinner the metal layer formed by evaporation is, the correspondingly worse the conductivity of the composite metal foil is, and the composite metal foil is not suitable for being used as a current collector of a lithium ion battery. Therefore, the composite aluminum foil prepared by the existing evaporation can only be used as a food packaging material, and the metal layer formed by the evaporation is very easy to fall off due to poor adhesion, and even if the composite aluminum foil is used as the food packaging material, a protective film needs to be compounded on the surface of the metal layer to prevent the fallen metal from polluting food, so that the existing composite metal foil and the preparation process thereof are difficult to be suitable for producing and preparing the composite copper foil film capable of being used as a current collector.

Disclosure of Invention

The to-be-solved technical problem of the utility model is to provide a compound copper foil membrane to reduce or avoid the aforementioned problem.

In order to solve the technical problem, the utility model provides a composite copper foil film, which comprises a substrate layer and conductive layers attached to two sides of the substrate layer, wherein, corona layers with the thickness of 1-2nm are formed on the surfaces of two sides of the substrate layer; a barrier layer with the thickness of 2-3nm is formed on the outer side of the corona layer; the conductive layer is formed on the outer side of the barrier layer, and the thickness of the base material layer is 6-10 mu m.

Preferably, the conductive layer comprises a metal copper sputtering layer, a metal copper electroplating layer and a protective layer in sequence from inside to outside; wherein the thickness of the metal copper sputtering layer is 5-15nm, the thickness of the metal copper electroplating layer is 100-500nm, and the thickness of the protective layer is 5-15nm.

Preferably, the thickness of the metal copper sputtering layer is 5-8nm, the thickness of the metal copper electroplating layer is 300-400nm, and the thickness of the metal chromium protective layer is 5-8nm.

Preferably, the substrate layer is a single-layer structure or a three-layer structure comprising an A layer, a B layer and a C layer.

The utility model discloses a carry out surface corona treatment to the substrate layer, improved the adhesive force of barrier layer, the barrier layer forms the cladding of substrate layer completely cut off to form hydrophobic structure on the surface of substrate layer, moisture when avoiding forming the conducting layer absorbs and the release problem, and the conducting layer of formation can obtain excellent electrical property and adhesive force under the prerequisite of not destroying substrate layer surface structure.

Drawings

The following drawings are only intended to illustrate and explain the present invention, and do not limit the scope of the present application.

Fig. 1 is a schematic structural diagram of a composite copper foil film according to an embodiment of the present invention.

Fig. 2 is a schematic diagram showing a structure of a composite copper foil film according to another embodiment of the present invention.

Fig. 3 is a schematic diagram showing a structure of a composite copper foil film according to another embodiment of the present invention.

Detailed Description

In order to clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will be described with reference to the accompanying drawings. Wherein like parts are given like reference numerals.

As shown in the figure, the invention provides a composite copper foil film capable of being used as a negative current collector of a lithium ion battery, the composite copper foil film is composed of a base material layer 1 and conducting layers 2 attached to two sides of the base material layer 1, and the conducting layers 2 are mainly composed of metal copper. As described above, since the evaporation temperature of metal copper is high, if the metal copper is attached to the surface of the base material layer 1 made of a polymer material by vapor deposition, uniformity of the surface structure of the base material layer 1 is deteriorated, and it is difficult to obtain a thickness necessary for sufficient electrical performance.

In view of this, the utility model provides a composite copper foil film, wherein, the thickness of the substrate layer 1 is 6-10 μm; the conductive layer 2 adopts a multi-layer conductive structure, and in the illustrated embodiment, the conductive layer 2 sequentially comprises a metal copper sputtering layer 21, a metal copper electroplating layer 22 and a protective layer 23 from inside to outside. The metal copper sputtering layer 21 is a layer of metal copper with the thickness of 5-15nm formed on the two side surfaces of the base material layer 1 by adopting a vacuum sputtering process, the metal copper electroplating layer 22 is a layer of metal copper with the thickness of 100-500nm formed on the outer surface of the metal copper sputtering layer 21 by adopting a water and electricity electroplating process, the protective layer 23 is a compact protective layer formed by passivating the outer surface of the metal copper electroplating layer 22 by adopting an electroplating or chemical corrosion process, and preferably, the protective layer 23 is a metal chromium protective layer with the thickness of 5-15nm formed by adopting an electroplating process. More preferably, the thickness of the metal copper sputtering layer 21 is 5 to 8nm, the thickness of the metal copper electroplating layer 22 is 300 to 400nm, and the thickness of the protective layer 23 is 5 to 8nm.

The utility model discloses an among the compound copper foil membrane, the compactness and the adhesive force on the metal copper sputtering layer that vacuum sputtering formed are far superior to the coating by vaporization technology, and because required thickness is very thin, the functioning speed of substrate layer can be very fast, has stopped basically that fusing or scalding the possibility of the defect of class appear in the substrate layer. The thickness of the metal copper sputtering layer is very thin, but basic conductive performance can be provided, so that a thicker metal copper layer can be further grown on the surface of the metal copper sputtering layer by means of water electroplating. Through the combination of vacuum sputtering technology and water electroplating process, the utility model discloses can obtain excellent electric property and adhesive force under the prerequisite of not destroying substrate layer surface structure, will further explain this later.

In addition, in order to avoid the problem that the metal copper layer adhesive force that leads to because the surface structure of substrate layer is inhomogeneous is not enough, the utility model discloses a modified substrate layer 1 is still provided in the utility model discloses an in the embodiment, the utility model discloses a substrate layer 1 is made by the polyester film who has added polyester function masterbatch, substrate layer 1 can be the polyester film (fig. 1) of the individual layer structure who has added polyester function masterbatch, or the top layer has added the polyester film (fig. 2) of the three layer construction who contains A layer, B layer, C layer of polyester function masterbatch.

The polyester referred to in the present invention is a polyester comprising one or more selected from polybasic carboxylic acids containing dibasic acids and their ester-forming derivatives, and one or more selected from polyhydric alcohols containing dibasic alcohols; or polyesters formed from hydroxycarboxylic acids and their ester-forming derivatives; or a polyester formed from a cyclic ester. The polyester can be produced by a conventionally known method. For example, taking the preparation of PET as an example, it can be obtained by: a method of performing polycondensation after esterification of terephthalic acid and ethylene glycol; or a method in which an alkyl ester of terephthalic acid such as dimethyl terephthalate is subjected to a transesterification reaction with ethylene glycol and then subjected to polycondensation. The polyester of the present invention is preferably PET.

In a specific embodiment, the polyester film forming the substrate layer 1 is a single-layer polyester film containing 5 to 20wt% of polyester functional master batch, or is a three-layer polyester film containing an a layer, a B layer and a C layer, wherein the a layer and the C layer contain 5 to 20wt% of polyester functional master batch, and the polyester functional master batch is prepared from the following raw materials in parts by weight: 30-50 parts of poly (m-xylylene diamide), 1-3 parts of cobalt neodecanoate, 3-5 parts of dibutyl hydroxy toluene, 5-10 parts of 1, 4-diiodobenzene, 20-30 parts of silicon dioxide and 50-100 parts of PET.

The polyester functional master batch of the present invention can be prepared in a pellet or chip form, and added to a common polyester in the process of producing a polyester film to prepare the substrate layer 1 of the present invention. For example, 80 to 95wt% of polyester without other components and 5 to 20wt% of the polyester functional masterbatch of the present invention may be melt-blended, and then the substrate layer 1 of a single-layer structure may be produced by a process such as stretching, or the surface layer structure of the substrate layer 1 of the present invention may be obtained by a multilayer co-extrusion process.

The raw material components of the polyester functional master batch can be uniformly mixed in the form of granules, and then the polyester functional master batch can be obtained by extrusion and granulation by using equipment such as an extruder.

In one embodiment, at room temperature, 50-100 parts by weight of powdered PET, 20-30 parts by weight of nano-silica, 30-50 parts by weight of powdered poly (m-xylylene diamide), 1-3 parts by weight of powdered cobalt neodecanoate, 3-5 parts by weight of powdered dibutyl hydroxy toluene and 5-10 parts by weight of powdered 1, 4-diiodobenzene are added into a high-speed mixer for pre-dispersion and mixing, and the rotation speed is 1500-2000 rpm, and the mixture is mixed for 30-60 minutes to form a mixture. And then carrying out melt extrusion through a double-screw extruder, and then carrying out water-cooling granulation or slicing to obtain the polyester functional master batch.

In another embodiment, for example, after preparing a chip for obtaining the polyester functional masterbatch, 5 to 20wt% of the polyester functional masterbatch is added to 80 to 95wt% of PET particles to be uniformly mixed, and the two are melt-blended, and finally the substrate layer 1 with a single-layer structure is obtained through a process such as stretching, or the surface layer structure of the substrate layer 1 with a three-layer structure is obtained through a multilayer co-extrusion process.

The preparation method of the polyester film for the composite copper foil film of the present invention is further described below by taking a single-layer polyester film as an example. The preparation method of the polyester film for the composite copper foil film comprises the following steps:

the components with the following weight ratio: 80-95 wt% of PET resin and 5-20 wt% of polyester functional master batch are respectively metered by an electronic scale and enter a mixing bunker to be mixed to prepare a mixture.

Then the mixture enters an exhaust type double-screw extruder, and the temperature of the double-screw extruder is adjusted to be 270-280 ℃.

After the materials are melted in an extruder, the materials are filtered and extruded to be made into thick sheets. The thickness and the profile of the slab can be adjusted by the extrusion amount of an extruder, the rotating speed of a casting sheet roller and the opening degree of a die head.

Preheating the thick sheet at 50-90 ℃, entering an infrared heating zone at 300-500 ℃, and longitudinally stretching at a linear speed of 40-150 m/min, wherein the longitudinal stretching ratio is 4.0, thus obtaining the stretched sheet.

Preheating the stretched sheet at the temperature of 90-120 ℃, and transversely stretching the sheet at the temperature of 100-160 ℃, wherein the transverse stretching ratio is 3.8. Then the mixture is shaped at the temperature of 160-240 ℃, and then is cooled at the temperature of 100-50 ℃ to prepare the polyester film for the composite copper foil film.

The thickness of the polyester film is 6-10 μm.

The preparation method of the polyester film for the composite copper foil film of the present invention is further described below by taking a three-layer polyester film as an example. The preparation method of the polyester film for the composite copper foil film comprises the following steps:

And then the mixture enters an exhaust type double-screw extruder E.

100% of PET resin is put into a pre-crystallizer, pre-crystallized for 15 minutes at the temperature of 160 ℃, and then the PET material enters a drying tower, is dried for 6 hours at the temperature of 160 ℃ and then enters a single-screw extruder F.

The temperature of the twin-screw extruder E and the twin-screw extruder F is adjusted to 270 ℃ to 280 ℃.

After materials are melted in the two extruders, the materials extruded by the double-screw extruder E are used as the layer A and the layer C on the surface, the materials extruded by the single-screw extruder F are used as the layer B in the middle, and a three-layer composite thick sheet is prepared by a multi-layer co-extrusion process. The thickness and the profile of the thick sheet can be adjusted by the extrusion amount of the extruder, the rotating speed of the sheet casting roller and the opening degree of the die head.

Preheating the stretched sheet at the temperature of 90-120 ℃, and transversely stretching the sheet at the temperature of 100-160 ℃, wherein the transverse stretching ratio is 3.8. Then shaping at 160-240 ℃, and cooling at 100-50 ℃ to obtain the three-layer polyester film.

The thickness of the prepared polyester film is 6-10 μm, wherein the thickness of the layer A is 1-2 μm, the thickness of the layer B is 2-8 μm, and the thickness of the layer C is 1-2 μm.

Examples 1 to 5

According to the weight parts of the raw materials in the following table, polyester functional master batch chips are respectively prepared and then added with common PET resin to prepare the polyester film with a single-layer structure for the composite copper foil film.

	Example 1	Example 2	Example 3	Example 4	Example 5
						Poly (m-xylylene diamide)	30	35	40	45	50
Cobalt neodecanoate	1	1.5	2	2.5	3
						Dibutylhydroxytoluene	3	3.5	4	4.5	5
1, 4-diiodobenzene	5	7	7.5	8	10
						Silicon dioxide	20	22	25	27	30
PET	50	65	75	85	100
						Amount of slices to prepare a monolayer substrate layer	5wt％	10wt％	13wt％	15wt％	20wt％
Thickness of the substrate layer	6	7	8	9	10

Comparative examples 6 to 10

In the same manner as in the above examples, comparative polyester films were prepared in the following raw material weight ratio.

The performance parameters of each polyester film obtained by preparation are respectively tested, meanwhile, films with the thickness of 8 mu m prepared by pure PET without any functional master batch are compared, and the performance parameters are shown in the following table.

And respectively forming metal copper sputtering layers on the surfaces of the two sides of the polyester film on the upper surface by a vacuum sputtering process, controlling the thickness of the metal copper layers on the two sides of the vacuum sputtering film to be 5nm, and testing the surface crack parameters of the prepared film.

The performance parameter through above-mentioned rete and the crackle condition of metallic coating are visible, through adding the utility model discloses a polyester film of polyester function masterbatch preparation, performance such as its porosity, water absorption rate, oxygen transmission rate all promote by a wide margin, do not see the expansion of obvious crackle after forming the metal copper conducting layer moreover.

Further, the resistivity difference of the metal copper sputtered layers on both sides of the polyester film shown in the above table was tested as shown in the following table.

Through adding the utility model discloses a polyester film of polyester function masterbatch preparation, the resistivity difference on the metal copper sputtering layer that forms is obviously less than the film that does not add the function masterbatch on it, shows that its both sides structure has more excellent uniformity.

Further, since the present invention needs to form the copper metal sputtering layer 21 on the surface of the substrate layer 1 at first, the substrate layer 1 needs to be controlled to operate at a lower temperature during sputtering. Although the mylar of the improved substrate layer 1 has excellent properties such as porosity, water absorption, oxygen transmission rate, etc., it is still necessary to prevent the interference of the moisture released when the mylar surface absorbs water at low temperature and then sputters with the vacuum degree.

Therefore, in a specific embodiment, in order to avoid the moisture absorption and release problem of the substrate layer 1 during sputtering, a barrier layer 11 is further formed on the outer side of the substrate layer 1 between the conductive layer 2 and the substrate layer 1 by sputtering to improve the performance of the conductive layer 2, as shown in fig. 3. Specifically, a layer of barrier layer 11 made of 2-3nm silicon dioxide can be deposited on each of the two side surfaces of the substrate layer 1 through a double-rotating cathode and intermediate frequency reactive magnetron sputtering method, so that the surface of the substrate layer 1 is coated and isolated, and a hydrophobic structure is formed on the surface of the substrate layer 1.

Still further, since the thickness of the barrier layer 11 is small, in order to improve the adhesion of the barrier layer 11 on the surface of the substrate layer 1, it is preferable to perform corona treatment on the surface of the substrate layer 1 before forming the barrier layer 11 by sputtering, so as to form a corona layer 10 having a thickness of 1 to 2nm on the surface of the substrate layer 1, form a barrier layer 11 having a thickness of 2 to 3nm on the outer side of the corona layer 10, and further form the conductive layer 2 on the outer side of the barrier layer 11, as shown in fig. 3. The corona treatment is a prior art, and the basic principle is that corona discharge is carried out on the surface of the treated plastic by using high frequency and high voltage to roughen the surface of the substrate layer 1 so as to increase the adhesion capability of the surface of the substrate layer 1 to the barrier layer 11.

The following further illustrates the preparation method of the composite copper foil film of the present invention.

As before, the utility model discloses compound copper foil membrane comprises substrate layer and the conducting layer of adhering to the both sides at the substrate layer, consequently, the utility model discloses a preparation method of compound copper foil membrane includes following step: firstly, a substrate layer is made of a polyester film added with polyester functional master batch. The process steps for preparing the substrate layer have been described in detail above and will not be repeated here.

Then carrying out corona treatment on the surfaces of the two sides of the base material layer to form a corona layer; then forming a barrier layer on the outer side of the corona layer; and finally, forming the conductive layer on the outer side of the barrier layer.

Further, as described above, the conductive layer includes a metal copper sputtering layer, a metal copper electroplating layer, and a protective layer in this order from the inside to the outside. Thus, the forming of the conductive layer includes: forming a metal copper sputtering layer on the outer side of the barrier layer by adopting a vacuum sputtering process; growing a metal copper electroplating layer on the outer surface of the metal copper sputtering layer by adopting a water electroplating process; and forming a protective layer on the outer surface of the metal copper electroplating layer through an electroplating process.

The polyester films prepared in examples 1 to 5 were used as a base material layer, and were subjected to corona treatment, sputtering of a barrier layer, sputtering of a metal copper sputtering layer, electroplating of a metal copper electroplating layer, and electroplating of a protective layer, respectively, to prepare a composite copper foil film having the following parameters.

It is visible through measuring parameter, the utility model discloses a compound copper foil membrane possesses excellent electrical property, and conducting layer adhesive force is extremely strong moreover, and the condition that the conducting layer peeled off can hardly appear in the conventional use.

It should be understood by those skilled in the art that while the present invention has been described in terms of several embodiments, it is not intended that each embodiment include only a single embodiment. The description is given for clearness of understanding only, and it is to be understood that all matters in the embodiments are to be interpreted as including all technical equivalents which are encompassed by the claims.

The above description is only exemplary of the present invention, and is not intended to limit the scope of the present invention. Any equivalent changes, modifications and combinations that may be made by those skilled in the art without departing from the spirit and principles of the invention should be considered within the scope of the invention.

Claims

1. The composite copper foil film is composed of a base material layer (1) and conducting layers (2) attached to two sides of the base material layer (1), and is characterized in that corona layers (10) with the thickness of 1-2nm are formed on the surfaces of the two sides of the base material layer (1); a barrier layer (11) with the thickness of 2-3nm is formed on the outer side of the corona layer (10); the conducting layer (2) is formed on the outer side of the barrier layer (11), and the thickness of the substrate layer (1) is 6-10 mu m.

2. The composite copper foil film according to claim 1, wherein the conductive layer (2) comprises a sputtered layer of metal copper (21), an electroplated layer of metal copper (22), and a protective layer (23) in this order from the inside to the outside; wherein the thickness of the metal copper sputtering layer (21) is 5-15nm, the thickness of the metal copper electroplating layer (22) is 100-500nm, and the thickness of the protective layer (23) is 5-15nm.

3. The composite copper foil film according to claim 2, wherein the thickness of the sputtered layer of metal copper (21) is 5 to 8nm, the thickness of the electroplated layer of metal copper (22) is 300 to 400nm, and the thickness of the protective layer (23) is 5 to 8nm.

4. The composite copper foil film according to claim 2, wherein the substrate layer (1) has a single-layer structure.

5. The composite copper foil film according to claim 2, wherein the substrate layer (1) has a three-layer structure including a layer a, a layer B and a layer C.