Ultrathin composite current collector, preparation equipment and preparation method

Abstract

The invention provides an ultra-thin composite current collector, a preparation device and a preparation method, the ultra-thin composite current collector comprises a current collector main body, the current collector main body comprises a polymer film layer and a first coating, the first coating is arranged on the polymer film layer, and the polymer film layer is arranged on the first coating. The current collector body is provided with a reduction area used for reducing the thickness of the polymer film layer on the side where the polymer film layer is located, a second coating is arranged on the current collector body, the first coating is located on the upper surface of the polymer film layer, and the second coating is located on the lower surface of the polymer film layer. The thickness of the polymer film layer can be greatly reduced, the weight of the composite current collector can be reduced, the energy density of the battery can be improved, meanwhile, the polymer film layer is thicker when the first coating is formed, and the polymer film layer cannot be burnt through by high-temperature particles of materials forming the first coating; and when the second coating is formed, high-temperature particles forming the second coating do not penetrate through the polymer film layer and the first coating, so that the whole composite current collector is ensured not to be burnt through.

Description

Technical Field

[0001] The present invention relates to the field of current collectors, and in particular to an ultra-thin composite current collector, a preparation device and a preparation method. Background Art

[0002] The composite current collector usually has good electrical conductivity and mechanical strength. It is responsible for carrying the active materials of the positive and negative electrodes, and collects the current generated by the electrochemical reaction for external output. At the same time, the current collector can also effectively disperse and transfer the heat generated inside the battery cell, improve the heat dissipation effect of the battery cell, and help maintain the temperature stability of the battery cell. The physicochemical properties of the current collector greatly affect the performance of lithium batteries. The main physical indicators of the current collector include thickness, thickness uniformity, surface density, surface roughness, tensile strength, elongation and porosity, and the chemical indicators include oxidation resistance, corrosion resistance and heat resistance. The composite current collector is a "sandwich" structure. When pierced by sharp objects, the sandwich film layer of the "sandwich" structure will wrap the sharp objects, prevent the positive and negative electrodes from contacting each other, and thus prevent the battery from short-circuiting and burning. In the current production process of the composite current collector, due to the thinness of the composite current collector, under the impact of high-temperature particles, the film sandwich layer is easily burned through to form voids, which easily causes quality defects of the composite current collector, so the existing technology needs to be improved and improved. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide an ultra-thin composite current collector, a preparation device and a preparation method.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides an ultra-thin composite current collector, comprising a current collector body, wherein the current collector body comprises a polymer film layer and a first coating, wherein the first coating is arranged on the polymer film layer, and the current collector body is provided with a reduction area for reducing the thickness of the polymer film layer on the side where the polymer film layer is located, and a second coating is arranged on the current collector body, wherein the first coating is located on the side where the upper surface of the polymer film layer is located, and the second coating is located on the side where the lower surface of the polymer film layer is located.

[0006] In a preferred embodiment, in the ultra-thin composite current collector, the thickness of the polymer film layer is 6 um to 20 um.

[0007] In a preferred embodiment, for the ultra-thin composite current collector, the thickness of the first coating layer is 500nm to 1500nm, and the thickness of the second coating layer is 500nm to 1500nm.

[0008] In a preferred embodiment, in the ultra-thin composite current collector, the second coating is disposed on the opposite side of the first coating, and a transition layer is further disposed between the first coating and the polymer film layer.

[0009] In a preferred embodiment, the ultra-thin composite current collector, the current collector body also includes a pole ear portion, the thickness of the polymer film layer in the reduction area where the pole ear portion is located is zero, and the second coating is arranged on the side of the polymer film layer away from the first coating.

[0010] In a preferred embodiment, the length of the ear portion of the ultra-thin composite current collector is 3um-50um.

[0011] In a preferred embodiment, the ultra-thin composite current collector, the current collector body further includes a transition piece, the base piece of the transition piece is overlapped and connected with the outer side of the second coating layer, and the extension piece of the transition piece is connected with the pole ear portion.

[0012] In a preferred embodiment, in the ultra-thin composite current collector, a bonding area is provided at the ear portion on the side where the reduction area is located, and the second coating fills the bonding area.

[0013] The present invention also provides an ultra-thin composite current collector preparation device, comprising a vacuum chamber, in which an evaporation source and a winding mechanism for unfolding a polymer film are arranged, the winding mechanism comprising a unwinding device, a first cooling main drum, a second cooling main drum and a winding device, the polymer film is unwound from the unwinding device, passed through the first cooling main drum and the second cooling main drum, and then retracted by the winding device, and a laser thinning machine is arranged between the first cooling main drum and the second cooling main drum.

[0014] The present invention also provides a method for preparing an ultra-thin composite current collector, comprising the following steps:

[0015] Flattening the polymer film;

[0016] The polymer film is subjected to a coating treatment, and a first coating is applied on one surface of the polymer film to form a current collecting body;

[0017] Performing a thinning process on the polymer film, thinning the polymer film side of the current collector, and reducing the thickness of the polymer film layer of the current collector;

[0018] The current collecting body is subjected to a coating treatment, and a second coating is formed on the surface of the current collecting body.

[0019] Compared with the prior art, the present invention provides an ultra-thin composite current collector, a preparation device and a preparation method, wherein the ultra-thin composite current collector includes a current collector body, the current collector body includes a polymer film layer and a first coating, the first coating is arranged on the polymer film layer, the current collector body is provided with a reduction area for reducing the thickness of the polymer film layer on the side where the polymer film layer is located, and the current collector body is provided with a second coating, the first coating is located on the side where the upper surface of the polymer film layer is located, and the second coating is located on the side where the lower surface of the polymer film layer is located. The present invention can greatly reduce the thickness of the polymer film layer, reduce the weight of the composite current collector, and improve the energy density of the battery. At the same time, since the polymer film layer is thicker when the first coating is formed, the high-temperature particles of the material constituting the first coating will not burn through the polymer film layer during the formation of the first coating. When forming the second coating, due to the presence of the first coating and the polymer film layer, the high-temperature particles forming the second coating will not pass through the polymer film layer and the first coating, thereby ensuring that the entire composite current collector will not be burned through. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a current collector body of the ultra-thin composite current collector provided by the present invention in one state.

[0023] Figure 2 This is a schematic structural diagram of another state of the current collector body of the ultra-thin composite current collector provided by the present invention.

[0024] Figure 3 This is a schematic structural diagram of an embodiment of an ultra-thin composite current collector with a tab structure provided by the present invention.

[0025] Figure 4 This is a schematic structural diagram of another embodiment of the ultra-thin composite current collector with a tab structure provided by the present invention.

[0026] Figure 5 A schematic structural diagram of a winding mechanism of an ultra-thin composite current collector preparation device provided by the present invention.

[0027] Description of Figure Numbers:

[0028] Current collector 100

[0029] Polymer film layer 10

[0030] First coating 11

[0031] Second coating 12

[0032] Reduction Zone 13

[0033] Pole ear 14

[0034] Adapter 15

[0035] Substrate 16

[0036] Extension piece 17

[0037] Binding zone 18

[0038] Unwinding device 210

[0039] First cooling main drum 220

[0040] Second cooling main drum 230

[0041] Laser Thinning Machine 240

[0042] Winding device 250

[0043] Evaporation crucible 260 DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0046] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0047] like Figure 1 , Figure 2 , Figure 3 As shown, the present invention provides an ultra-thin composite current collector, a preparation device and a preparation method, wherein the ultra-thin composite current collector comprises a current collector body 100, the current collector body 100 comprises a polymer film layer 10 and a first coating layer 11, the first coating layer 11 is arranged on the polymer film layer 10, the current collector body 100 is provided with a reduction area 13 for reducing the thickness of the polymer film layer 10 on the side where the polymer film layer 10 is located, and the current collector body 100 is provided with a second coating layer 12, the first coating layer 11 is located on the side where the upper surface of the polymer film layer 10 is located, and the second coating layer 12 is located on the side where the lower surface of the polymer film layer 10 is located. The present invention can greatly reduce the thickness of the polymer film layer 10, reduce the weight of the composite current collector, and improve the energy density of the battery. At the same time, since the polymer film layer is thicker when the first coating layer is formed, the high-temperature particles of the material constituting the first coating layer will not burn through the polymer film layer during the formation of the first coating layer. When forming the second coating, due to the presence of the first coating and the polymer film layer, the high-temperature particles forming the second coating will not pass through the polymer film layer and the first coating, thereby ensuring that the entire composite current collector will not be burned through and thus no holes will be formed.

[0049] The present invention also provides a method for preparing an ultra-thin composite current collector, comprising the following steps:

[0050] S1, flattening the polymer film;

[0051] S2, coating the polymer film, coating one surface of the polymer film with a first coating layer 11 to form a current collecting body 100;

[0052] S3, performing a thinning process on the polymer film, thinning the polymer film side of the current collector 100, and reducing the thickness of the polymer film layer 10 of the current collector 100;

[0053] S4 , performing a coating process on the current collecting body 100 , coating the surface of the current collecting body 100 with a second coating layer 12 .

[0054] Preferably, in the ultra-thin composite current collector provided by the present invention, the thickness of the polymer film layer 10 is 6um to 20um. Preferably, in the ultra-thin composite current collector provided by the present invention, the thickness of the first coating 11 is 500nm to 1500nm, and the thickness of the second coating 12 is 500nm to 1500nm. Preferably, in the ultra-thin composite current collector provided by the present invention, the polymer film layer 10 is centered, and the second coating 12 is arranged on the opposite side of the first coating 11. In the present invention, the first coating 11 and the second coating 12 are formed by vacuum coating. The equipment for vacuum coating can be physical and chemical lamination, such as vacuum evaporation, magnetron sputtering, etc.

[0055] Specifically, firstly, a polymer film with a thickness of 6um-20um is taken, and then a first coating 11 is formed on one of the surfaces in the thickness direction of the polymer film by vacuum coating on the polymer film, and then the polymer film is thinned, and the thinned thickness can be 3um-16um to obtain a polymer film of a certain thickness; finally, a second coating 12 is formed on one side of the polymer film thickness direction relative to the first coating 11 by vacuum coating. In the above manner, the thickness of the polymer film layer 10 can be greatly reduced, the weight of the composite current collector can be reduced, and the energy density of the battery can be improved. Most importantly, the present invention first forms the first coating 11 on the thicker polymer film layer 10, and then thins the polymer film layer 10 from the other side of the polymer film layer 10 to form the first coating 11 and form the second coating 12 on the film. Due to the presence of the first coating 11, the high-temperature particles of the second coating 12 will not burn through the film and the first coating 11 when the first coating 11 is formed. By the above method, the appearance of film holes can be completely avoided.

[0056] The polymer film can be a film made of any non-conductive material. The polymer film layer 10 of the present invention can be a film formed by one or more of polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polypropylene, acrylonitrile-butadiene-styrene copolymer, polyvinyl alcohol, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, sodium polystyrene sulfonate, polyacetylene, silicone rubber, polyformaldehyde, polyphenylene oxide, polyphenylene sulfide, polyethylene glycol, polysulfur nitride polymer materials, polyphenylene, polypyrrole, polyaniline, polythiophene, polypyridine, cellulose, starch, protein, epoxy resin, and phenolic resin.

[0057] In the present invention, the thinning device can be a laser thinning machine 240. The principle is that the polymer film is vaporized under the action of laser to form a polymer film of a certain thickness. At the same time, this method is used to facilitate the composite current collector of the present invention to be formed in a vacuum coating device at one time. This is when the film is coated in the vacuum coating device, the interior is vacuum, and the vaporized polymer film can be vacuumed away without opening the vacuum for further processing, which reduces costs, improves efficiency, and prevents the coating from being oxidized. A transition layer can also be formed between the first coating 11 and the second coating 12 and the polymer film layer 10, that is, a transition layer is also provided between the first coating 11 and the polymer film layer 10, and a transition layer is also provided between the second coating 12 and the polymer film layer 10. The transition layer can improve the bonding force between the coating and the polymer film and is not easy to fall off. The first coating 11, the second coating 12, and the transition layer can all be made of materials such as aluminum oxide, silicon nitride, copper alloy, and aluminum alloy. When preparing the transition layer, a 6um-20um polymer film is first used, and then a transition layer is formed on the polymer film, and then a first coating layer 11 and a second coating layer 12 are formed on the transition layer.

[0058] Preferably, the ultra-thin composite current collector provided by the present invention is Figure 3 As shown, the current collector body 100 further includes a pole ear portion 14, the thickness of the polymer film layer 10 in the reduction zone 13 where the pole ear portion 14 is located is zero, and the second coating 12 is disposed on the side of the polymer film layer 10 away from the first coating 11. Preferably, in the ultra-thin composite current collector provided by the present invention, the length of the pole ear portion 14 is 3um-50um. During preparation, firstly, a polymer film with a thickness of 6um-20um is taken; then, a first coating 11 is formed on one of the surfaces of the polymer film in the thickness direction by vacuum coating method; after the first coating 11 is formed, a pole ear portion 14 is separated from the polymer film, and a thinning device is used to thin the non-pole ear portion 14 area to a specified thickness, but a certain amount of polymer film is retained, and at the same time, the thinning device is used to remove all the polymer film of the pole ear portion 14, so that only the first coating 11 is retained in the pole ear portion 14; then, a vacuum coating device is used to vacuum coat the non-pole ear portion 14 area on the thinned side of the polymer film to form a second coating 12, thereby forming a composite current collector with a pole ear structure. The length of the pole ear portion 14 is 3um-50um.

[0059] Preferably, in the ultra-thin composite current collector provided by the present invention, the current collector body 100 further includes a transfer sheet 15, the base sheet 16 of the transfer sheet 15 is overlapped and connected with the outer side of the second coating 12, and the extension sheet 17 of the transfer sheet 15 is connected with the pole ear portion 14. First, a composite current collector with a pole ear structure is taken, and then the transfer sheet 15 is stacked on the surface of the second coating 12; ultrasonic welding is first used to weld the second coating 12 and the base sheet 16 of the transfer sheet 15, and the extension sheet 17 of the transfer sheet 15 extends out of the end of the film; then the extension sheet 17 of the transfer sheet 15 is welded to the pole ear portion 14, thereby completing the welding of the pole ear.

[0060] like Figure 4 As shown, preferably, in the ultra-thin composite current collector provided by the present invention, the pole ear portion 14 is provided with a bonding area 18 on the side where the reduction area 13 is located, and the second coating 12 fills the bonding area 18. In the composite current collector with such a pole ear structure, a bonding area 18 is also provided on the polymer film, and the film of the bonding area 18 is also completely removed by laser, so that the first coating 11 and the second coating 12 can be in direct contact. Therefore, when the current collector of the present invention is used in a battery, the current gathered by the second coating 12 will pass through the first coating 11 and converge along the pole ear. With such a setting, the conventional method of welding the adapter 15 to the pole ear can be eliminated, thereby reducing the mass of the current collector and improving the energy density of the battery. It can also greatly reduce the cost of preparing the battery. In this structure, the preparation method can be: first, take a polymer film with a thickness of 6um-20um; then, use a vacuum coating method on the polymer film to form a first coating 11 on one of the surfaces in the thickness direction of the polymer film; after the first coating 11 is formed, separate the pole ear portion 14 on the polymer film, and let the thinning device thin the non-pole ear portion 14 area to a specified thickness, but retain a certain polymer film, and at the same time, let the thinning device remove all the polymer film of the pole ear portion 14, so that the pole ear portion 14 only retains the first coating 11, and define a bonding area 18 near the pole ear portion 14 where the polymer film is located, and its length can be 3um-10um; then use a vacuum coating device to vacuum coat the non-pole ear portion 14 area and the bonding area 18 on the thinned side of the polymer film to form a second coating 12, thereby forming a composite current collector with a pole ear structure that does not require a transition sheet 15.

[0061] like Figure 5As shown, the present invention also provides an ultra-thin composite current collector preparation device, including a vacuum chamber, in which an evaporation source and a winding mechanism for unfolding a polymer film are arranged, the winding mechanism includes an unwinding device 210, a first cooling main drum 220, a second cooling main drum 230 and a winding device 250, the polymer film is unwound from the unwinding device 210, and is retracted by the winding device 250 after passing through the first cooling main drum 220 and the second cooling main drum 230, and a laser thinning machine 240 is arranged between the first cooling main drum 220 and the second cooling main drum 230. Specifically, the evaporation source is an evaporation crucible 260, a roller is arranged between the unwinding device 210 and the first cooling main drum 220, two rollers are arranged between the first cooling main drum 220 and the second cooling main drum 230, and a roller is arranged between the winding device 250 and the second cooling main drum 230. After passing through the roller, the polymer film passes through the first cooling main drum 220. An evaporation crucible 260 is arranged under the first cooling main drum 220. The evaporation crucible 260 mainly contains the evaporation material to form a first coating 11 on one side of the polymer film. After passing through the first cooling main drum 220 and then passing through another roller, a laser thinning machine 240 is arranged on the side of the polymer film where the first coating 11 is not formed, so as to thin the polymer film to a predetermined thickness. After passing through another roller, the polymer film reaches the second cooling main drum 230. An evaporation crucible 260 is also arranged under the second cooling main drum 230, so as to evaporate one side of the thinned polymer film to form a second coating 12. After passing through the roller, the polymer film reaches the winding device 250 for winding.

[0062] In summary, the present invention provides an ultra-thin composite current collector, a preparation device and a preparation method, wherein the ultra-thin composite current collector comprises a current collector body, the current collector body comprises a polymer film layer and a first coating layer, the first coating layer is arranged on the polymer film layer, the current collector body is provided with a reduction area for reducing the thickness of the polymer film layer on the side where the polymer film layer is located, and the current collector body is provided with a second coating layer. The present invention can greatly reduce the thickness of the polymer film layer, reduce the weight of the composite current collector, and improve the energy density of the battery. At the same time, since the polymer film layer is thicker when the first coating layer is formed, the high-temperature particles of the material constituting the first coating layer will not burn through the polymer film layer during the formation of the first coating layer. When forming the second coating layer, due to the presence of the first coating layer and the polymer film layer, the high-temperature particles forming the second coating layer will not pass through the polymer film layer and the first coating layer, thereby ensuring that the entire composite current collector will not be burned through, and holes are avoided. Due to the presence of the first coating layer and the second coating layer, the current collector has sufficient thickness, and the high-temperature particles passing through the second coating layer to the first coating layer will not burn through the film and the first coating layer, thereby completely avoiding the appearance of film holes.

[0063] The present invention provides a method for preparing an ultra-thin composite current collector. First, a polymer film with a thickness of 6um-20um is taken, and then a first coating is formed on one of the surfaces in the thickness direction of the polymer film by a vacuum coating method on the polymer film, and then the polymer film is thinned. The thinned thickness can be 3um to 16um to obtain a polymer film of a certain thickness; finally, a second coating is formed on one side of the polymer film thickness direction relative to the first coating by a vacuum coating method. Through the above method, the thickness of the polymer film layer can be greatly reduced, the weight of the composite current collector can be reduced, and the energy density of the battery can be improved. Most importantly, the present invention first forms a first coating on a thicker polymer film layer, and then thins the polymer film layer from the other side of the polymer film layer to form the first coating and form the second coating on the film. Due to the presence of the first coating, the high-temperature particles of the second coating will not burn through the film and the first coating when the first coating is formed. Through the above method, the appearance of film holes can be completely avoided.

[0064] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An ultra-thin composite current collector, characterized in that: It includes a current collecting body, which includes a polymer film layer and a first coating, wherein the first coating is arranged on the polymer film layer, and the current collecting body is provided with a reduction area for reducing the thickness of the polymer film layer on the side where the polymer film layer is located, and a second coating is arranged on the current collecting body, wherein the first coating is located on the side where the upper surface of the polymer film layer is located, and the second coating is located on the side where the lower surface of the polymer film layer is located.

2. The ultra-thin composite current collector according to claim 1, characterized in that: The thickness of the polymer film layer is 6um to 20um.

3. The ultra-thin composite current collector according to claim 2, characterized in that: The thickness of the first coating layer is 500nm-1500nm, and the thickness of the second coating layer is 500nm-1500nm.

4. The ultra-thin composite current collector according to claim 1, characterized in that: The second coating layer is arranged on the opposite side of the first coating layer, a transition layer is arranged between the first coating layer and the polymer film layer, and a transition layer is arranged between the second coating layer and the polymer film layer.

5. The ultra-thin composite current collector according to claim 1, characterized in that: The current collecting body further includes a pole ear portion, the thickness of the polymer film layer in the reduction zone where the pole ear portion is located is zero, and the second coating is arranged on a side of the polymer film layer away from the first coating.

6. The ultra-thin composite current collector according to claim 5, characterized in that: The length of the pole ear portion is 3um-50um.

7. The ultra-thin composite current collector according to claim 5, characterized in that: The current collecting body further comprises a transfer plate, a base plate of which is overlapped and connected with the outer side of the second coating layer, and a protruding plate of which is connected with the pole ear portion.

8. The ultra-thin composite current collector according to claim 5, characterized in that: The pole ear portion is provided with a bonding area on the side where the reduction area is located, and the second coating fills the bonding area.

9. An ultra-thin composite current collector preparation device, characterized in that: It includes a vacuum cavity, in which an evaporation source and a winding mechanism for unfolding a polymer film are arranged, the winding mechanism includes a unwinding device, a first cooling main drum, a second cooling main drum and a winding device, the polymer film is unwound from the unwinding device, passed through the first cooling main drum and the second cooling main drum, and then retracted by the winding device, and a laser thinning machine is arranged between the first cooling main drum and the second cooling main drum.

10. A method for preparing an ultra-thin composite current collector, characterized in that: The steps include: Flattening the polymer film; The polymer film is subjected to a coating treatment, and a first coating is applied on one surface of the polymer film to form a current collecting body; Performing a thinning process on the polymer film, thinning the polymer film side of the current collector, and reducing the thickness of the polymer film layer of the current collector; The current collecting body is subjected to a coating treatment, and a second coating is formed on the surface of the current collecting body.

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