Current collector, battery and application thereof

Abstract

The invention discloses a current collector which is characterized by comprising a supporting layer, an anti-shrinkage viscous layer and a metal layer, anti-shrinkage viscous layers are arranged on the two sides of the support; a metal layer is arranged on the side, away from the supporting layer, of the anti-shrinkage viscous layer. According to the application, the anti-shrinkage viscous layer is arranged between the supporting layer and the metal layer, and the anti-shrinkage viscous layer is of a layer structure with viscosity and shrinkage resistance during curing. Based on the current collector comprising the anti-shrinkage viscous layer, the bonding between the supporting layer and the metal layer of the current collector can be realized, and the instability when the supporting layer and the metal layer are directly bonded is overcome; the whole current collector is stable in structure and performance. Meanwhile, on the basis of the current collector, production interference factors are reduced, and production operation is facilitated; and at least when the anti-shrinkage viscous layer is ensured to provide viscosity, possible adverse effects during curing are reduced, and the production difficulty of the current collector is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and more specifically, to a current collector, a battery and its applications. Background Art

[0002] The composite current collector for lithium batteries is a new type of current collector material with a "sandwich" structure. The middle support layer usually uses polymer insulating resins such as PET (polyethylene terephthalate), PP (polypropylene), PI (polyimide), etc. as the film substrate, and then a metal layer, such as a copper foil layer, is made on the surface of the film substrate by means of magnetron sputtering, vacuum evaporation plating, electroplating in water or a combination of multiple processes, to form a composite current collector sandwich structure. Compared with the metal current collector formed by traditional all-metal materials, the composite current collector has advantages such as high energy density and less metal consumption. Therefore, it has become a current development trend for the composite current collector to replace the traditional metal current collector.

[0003] Although the composite current collector has certain advantages compared with the traditional all-metal current collector, there are still deficiencies; the support layer of the composite current collector uses materials such as PET, PP, PI, etc., and the adhesion of the metal layer on this type of support layer is weak and it is easy to separate from the support layer, resulting in the stability of the current collector being affected. For this reason, the prior art has proposed methods such as an adhesion-enhancing layer to solve the problem of the combination of the support layer and the metal layer, including coating a viscous glue solution on the support layer and compounding it with the metal layer through the formed viscous layer. However, there will be new problems in the production process based on this type of technology; during the curing process, it includes the gel setting stage of evaporating components such as water and the aging stage after compounding; however, during the aging process, the viscous layer will shrink in the plane direction; when the viscous layer shrinks, it will drive the support layer and the metal layer on both sides of it to shrink, resulting in the overall wrinkling of the current collector and unable to obtain a qualified current collector; on the other hand, it may cause some viscous glue solution to detach from the support layer, unable to spread completely on the support layer, and may drive partial deformation of the support layer, such as warping, etc., and voids are generated between different layers, resulting in a weakened effect of bonding the support layer and the metal layer and subsequent easy detachment.

[0004] Therefore, the prior art urgently needs a viscous layer that can be applied between the support layer and the metal layer to provide an adhesive effect, and at the same time it has anti-shrinkage performance during curing to overcome the adverse effects brought by shrinkage in the actual production process. Summary of the Invention

[0005] The present invention aims to overcome at least one of the above-mentioned deficiencies of the prior art, and provides a current collector, a battery and its applications. The current collector based on the anti-shrinkage viscous layer contained in the present application can effectively avoid the adverse effects brought by shrinkage during the curing process in the production process, and ensure and improve the firm combination between the support layer and the metal layer.

[0006] The technical solution adopted by the present invention is a current collector, which includes a support layer, a shrinkage-resistant adhesive layer, and a metal layer; the shrinkage-resistant adhesive layer is provided on at least one side of the support layer; the metal layer is provided on the side of the shrinkage-resistant adhesive layer away from the support layer. Further, the shrinkage-resistant adhesive layer has adhesiveness; and the curing shrinkage rate ≤ 3%. The shrinkage-resistant adhesive layer is a layer structure with adhesiveness and shrinkage resistance during curing. Based on the shrinkage-resistant adhesive layer in the current collector of the present application, the bonding between the support layer and the metal layer can be realized, and the instability during the direct bonding of the support layer and the metal layer can be overcome; at the same time, during the production process of the specific current collector, the shrinkage-resistant adhesive layer of the present application can effectively prevent shrinkage during the curing stage, prevent the shrinkage from driving the support layer and the metal layer to deform and wrinkle, and facilitate maintaining the planar shape to closely fit the plane of the support layer and the metal layer; and it can also prevent the coverage area of the shrinkage-resistant adhesive layer from becoming smaller after shrinkage, ensure the adhesive action area, and improve the bonding strength. Further, the curing shrinkage rate of the shrinkage-resistant adhesive layer ≤ 2%; more preferably, the curing shrinkage rate range of the shrinkage-resistant adhesive layer is 0.1% - 0.5%.

[0007] Further, the shrinkage-resistant adhesive layer has insulation, tensile strength, extensibility, and adhesiveness; further, the shrinkage-resistant adhesive layer can be formed by curing a shrinkage-resistant adhesive liquid; the shrinkage-resistant adhesive includes a mixed component A and component B, and the component A is at least one of polyurethane resin, acrylic resin, epoxy resin, polyester resin, polyimide, silicone polymer, and their modified compounds; the component B liquid is at least one of amino resin, isocyanate, aziridine crosslinking agent, carbodiimide, silane coupling agent, and silicone-based tackifier; wherein, the ratio of component A to component B is: (90 - 99):(1 - 5). The shrinkage-resistant adhesive layer of the present application not only exists as an adhesive layer, but also has strong mechanical properties, which is beneficial to enhancing the mechanical properties of the overall current collector.

[0008] Further, the shrinkage-resistant adhesive liquid further includes a C filler component, wherein the ratio of component A, component B, and the C filler component is: (90 - 99):(1 - 5):(1 - 5); the C filler component includes at least one of silica, aluminum hydroxide, alumina, talc powder, aluminum nitride, boron nitride, silicon carbide, barium sulfate, barium titanate, strontium titanate, boehmite, calcium carbonate, calcium silicate, mica, graphite, magnesium oxide, magnesium hydroxide, kaolin, starch, montmorillonite, titanium dioxide, zinc sulfide, calcium bicarbonate, calcium phosphate, calcium hydrogen phosphate, calcium sulfate, carbon black, graphite, multi-walled and single-walled carbon nanotubes, carbon nanofibers, polytetrafluoroethylene particles, polyurethane microparticles, rubber particles, polyamide microparticles, silicone particles, graphene, nanotube structures, and antimony trioxide.

[0009] Further, the support layer is directly adhered to the metal layer through an anti-shrinkage adhesive layer to form a negative electrode current collector. Compared with forming a metal layer on the support structure base film by means of magnetron sputtering or hydroelectroplating on the surface of the support layer, in this application, by utilizing the adhesive property of the anti-shrinkage adhesive layer, the metal layer can be directly compounded on the anti-shrinkage adhesive layer, thereby forming the corresponding negative electrode current collector. The process of forming the negative electrode current collector is simpler and faster, does not require complex and expensive production equipment, is convenient for mass production, and overcomes the problem of difficult mass production in the prior art. The anti-shrinkage adhesive layer can be a pre-formed semi-cured layer structure, which is compounded directly with the support layer and the metal layer; or an anti-shrinkage adhesive liquid can be coated on the surface of the support layer to form an anti-shrinkage adhesive layer, and then further compounded with the metal layer.

[0010] Further, the tensile strength of the anti-shrinkage adhesive layer is ≥250 Mpa, and the elongation at break is ≥80%. Further still, the tensile strength of the anti-shrinkage adhesive layer is 280 Mpa - 400 Mpa; further still, the tensile strength of the anti-shrinkage adhesive layer is 280 - 350 Mpa; further, the bonding force between the anti-shrinkage adhesive layer and the metal layer ranges from 3 N / 25 mm to 30 N / 25 mm; further still, the bonding force between the anti-shrinkage adhesive layer and the metal layer ranges from 3 N / 25 mm to 20 N / 25 mm; further still, the bonding force between the anti-shrinkage adhesive layer and the metal layer ranges from 3 N / 25 mm to 15 N / 25 mm. In addition to the adhesive property, the anti-shrinkage adhesive layer also has good mechanical properties, including tensile strength and elongation at break. It is located between the support layer and the metal layer, and by utilizing its mechanical properties, the toughness, safety, etc. of the current collector can be further improved on the basis of the support layer substrate.

[0011] Further, the bonding force between the anti-shrinkage adhesive layer and the support layer ranges from 3 N / 25 mm to 30 N / 25 mm; the bonding force between the anti-shrinkage adhesive layer and the metal layer ranges from 3 N / 25 mm to 30 N / 25 mm.

[0012] Further, a cavity for accommodating functional solid fillers is left in the anti-shrinkage adhesive layer. The anti-shrinkage adhesive layer can be filled with functional solid fillers to further improve the performance of the anti-shrinkage adhesive layer without affecting the thickness. The functional solid fillers include at least one of silicon dioxide, aluminum hydroxide, aluminum oxide, talcum powder, aluminum nitride, boron nitride, silicon carbide, barium sulfate, barium titanate, strontium titanate, boehmite, calcium carbonate, calcium silicate, mica, graphite, magnesium oxide, magnesium hydroxide, kaolin, starch, montmorillonite, titanium dioxide, zinc sulfide, calcium bicarbonate, calcium phosphate, calcium hydrogen phosphate, calcium sulfate, carbon black, graphite, multi-walled and single-walled carbon nanotubes, carbon nanofibers, polytetrafluoroethylene particles, polyurethane microparticles, rubber particles, polyamide microparticles, silicone particles, graphene, nanotube structures, and antimony trioxide.

[0013] Further, the thickness of the support layer is 1.9 to 6 μm; the thickness of the anti-shrinkage adhesive layer is 0.8 to 4 μm; the thickness of the metal layer is 0.8 to 3.5 μm. Further, the thickness of the metal layer is 0.8 to 1.5 μm; more preferably, the thickness of the metal layer is 1 to 1.5 μm. Further, the total thickness range of the current collector is 6 to 12 μm.

[0014] Further, the support layer is made of at least one of PET, PP, PI, PE, PVC, PBT, PC, PS, ABS, PA, PASF, PVDF, PEDOT, PANI, and PPy; that is, a support layer formed of at least one material among PET (polyethylene terephthalate), PP (polypropylene), PI (polyimide), PE (polyethylene), PVC (polyvinyl chloride), PBT (polybutylene terephthalate), PC (polycarbonate), PS (polystyrene), ABS (ternary copolymer of acrylonitrile (A)-butadiene (B)-styrene (S)), PA (polyamide), PASF (polyarylsulfone), PVDF (polyvinylidene fluoride), PEDOT (poly(3,4-ethylenedioxythiophene)), PANI (polyaniline), and PPy (polypyrrole). Further, the metal layer is at least one of copper, aluminum, titanium, nickel, cadmium, iron, and silver. Further, the metal layer is a copper layer. The metal layer is a copper foil layer; and there are ≤5 pinholes per square meter on the copper foil layer, and the diameter of the pinholes is ≤0.1 mm.

[0015] Further, a protective layer is further included, and the protective layer is disposed on the surface of the metal layer away from the support layer; the protective layer is formed of at least one material among chromium, tungsten, molybdenum, nickel, iron, titanium, niobium, zirconium, gold, silver, platinum, carbon, chromate compounds, silane compounds, and benzotriazole and its modified compounds. On the basis of the basic composite current collector structure, a protective layer structure can be added. The protective layer can prevent the conductive layer of the current collector from being chemically corroded or oxidized, can also enhance the mechanical strength of the current collector, and can improve the current-carrying capacity of the current collector and the electrode sheet. More preferably, the thickness of the protective layer is 0.01 to 0.15 μm; it is convenient to provide the function of the protective layer while hardly affecting the overall thickness of the current collector.

[0016] Further, the surface roughness Ra of the metal layer is ≤0.3 μm; however, the metal layer also has a certain surface roughness. In addition to directly improving the electrical conductivity, it can promote the formation of a mechanical bite interface between the metal layer and the insulating adhesive layer, and enhance the bonding between the metal layer and the insulating adhesive layer.

[0017] Further, the thermal shrinkage rate of the anti-shrinkage adhesive layer after being treated at 150°C for 30 minutes is ≤3%; further, the elongation rate of the current collector is ≥3%. More specifically, the thermal shrinkage rate of the anti-shrinkage adhesive layer after being treated at 150°C for 30 minutes is 0.9 - 2.5%. Further, the surface sheet resistance of the current collector is ≤23 mΩ. In this application, the anti-shrinkage adhesive layer is not produced by stretching on a certain length production line, but is directly coated and then cured. Its mechanical properties in the transverse and longitudinal directions are similar; although the test process is carried out based on the longitudinal length, in fact, its thermal shrinkage rate, tensile strength, and elongation at break are almost equal in the longitudinal and transverse directions, with an error not exceeding 3%. The thermal shrinkage rate, elongation at break, and tensile strength of the anti-shrinkage adhesive layer in this application should be understood as values that do not distinguish between the longitudinal and transverse directions, or can also be considered to represent both longitudinal and transverse values at the same time. The thermal shrinkage rate of the anti-shrinkage adhesive layer in this application is tested according to the JISC2151 standard. The thermal shrinkage rate of the anti-shrinkage adhesive layer in this application is ≤3%, which has excellent heat resistance and thermal stability, and is beneficial to improving the safety of applications in batteries.

[0018] Another object of this application is to provide a battery including the aforementioned current collector. Based on the current collector of this application, it is conducive to mass production, and is also conducive to forming a battery with high energy density and stable performance, promoting the development of corresponding negative electrode current collector application products.

[0019] Another object of this application is to provide an application of the aforementioned current collector or the aforementioned battery in a power vehicle.

[0020] Compared with the prior art, the beneficial effects of this application are as follows: In the current collector of this application, an anti-shrinkage adhesive layer is provided between the support layer and the metal layer, and the anti-shrinkage adhesive layer is a layer structure with adhesiveness and anti-shrinkage during curing. Based on the current collector of this application that includes an anti-shrinkage adhesive layer, the bonding between the support layer and the metal layer of the current collector can be realized, overcoming the instability when the support layer and the metal layer are directly bonded; the overall current collector shows stable structure and performance. At the same time, based on the current collector of this application, the production interference factors are reduced, and the production operation is convenient; at least while ensuring the adhesiveness provided by the anti-shrinkage adhesive layer, the possible adverse effects during curing are reduced, and the production difficulty of the current collector is lowered. For example, in the production process of a specific current collector, the anti-shrinkage adhesive layer in this application can effectively prevent shrinkage during the curing stage, prevent shrinkage from driving the support layer, metal layer, and even the entire current collector to deform, facilitate maintaining a planar shape, and closely fit with the planes of the metal layer and the support layer; and it can also prevent the coverage area of the anti-shrinkage adhesive layer from becoming smaller after shrinkage, ensure the adhesive action area, and improve the bonding strength; effectively avoid the influence of the curing process on the bonding effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the hierarchical structure of the current collector of this application.

[0022] Figure 2 Schematic diagram of the current collector hierarchical structure with a protective layer for this application.

[0023] Figure 3 Electron micrograph of the current collector hierarchical structure for this application.

[0024] Description of the drawings: Current collector 100, support layer 110, anti - shrinkage adhesive layer 120, metal layer 130, protective layer 140. Detailed implementation manners

[0025] The drawings of the present invention are only for illustrative purposes and should not be construed as limiting the present invention. To better illustrate the following embodiments, some components in the drawings may be omitted, enlarged or reduced, which does not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well - known structures and their descriptions in the drawings may be omitted.

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings and specific implementation manners. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention. For those embodiments where specific conditions are not indicated, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchase. Embodiment 1

[0027] This embodiment discloses a current collector 100, which includes a support layer 110, an anti - shrinkage adhesive layer 120, and a metal layer 130; the anti - shrinkage adhesive layer 120 is provided on at least one side of the support layer 110; the metal layer 130 is provided on the side of the anti - shrinkage adhesive layer 120 away from the support layer 110. In this embodiment, the anti - shrinkage adhesive layer 120 and the metal layer 130 can be sequentially arranged on both sides of the support layer 110 in the direction away from the support layer 110, as Figure 1 shown; specifically, the electron micrograph of the five - layer structure in this embodiment is as Figure 3As shown. Further, the anti-shrinkage adhesive layer 120 has adhesiveness; and the curing shrinkage rate ≤ 3%. The anti-shrinkage adhesive layer 120 is a layer structure with adhesiveness and anti-shrinkage property during curing; it can be formed by at least a viscous material with anti-shrinkage property during curing. Further, the curing shrinkage rate of the anti-shrinkage adhesive layer 120 ≤ 2%; furthermore, the curing shrinkage rate range of the anti-shrinkage adhesive layer 120 is 0.1% - 0.5%. Further, in this embodiment, the temperature range during the gel setting stage in the curing process of the anti-shrinkage adhesive layer 120 is 80 - 90 °C, and the temperature range during the post-curing stage after lamination is 50 - 90 °C; specifically, after the anti-shrinkage adhesive layer 120 is laminated with the support layer 110 and the metal layer 130, it is placed at 50 - 90 °C for 24 - 48 h for post-curing to obtain the current collector 100. The post-curing process can fully exert the performance of the anti-shrinkage adhesive layer 120 and improve the lamination effect.

[0028] The anti-shrinkage adhesive layer 120 has insulation, tensile strength, extensibility and adhesiveness, and can be formed by curing an anti-shrinkage adhesive liquid. The anti-shrinkage adhesive liquid includes a mixed component A and component B. Component A is at least one of polyurethane resin, acrylic resin, epoxy resin, polyester resin, polyimide, silicone polymer and its modified compounds. Component B is at least one of amino resin, isocyanate, aziridine crosslinking agent, carbodiimide, silane coupling agent and silicone-based tackifier. Among them, the weight ratio of component A to component B is (90-99):(1-5), and 93:3 can be selected in this embodiment. In component A of this embodiment, the polyurethane resin has a polyester backbone part and a polyether backbone part, and the mass ratio of the polyester backbone part to the polyether backbone part in the polyurethane resin ranges from (1:9) to (5:5). The polyester backbone can be formed by a polyester polyol compound, which is a compound manufactured by the reaction of low molecular weight polyols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 3-methylpentanediol, 1,6-hexanediol, hydrogenated bisphenol A, trimethylolpropane, and glycerol, etc., with polyacids such as succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid and hexahydrophthalic acid, etc., and is a compound with an ester structure and terminal hydroxyl groups. The polyether backbone can be formed by a polyether polyol, and the polyether polyol is preferably a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms (such as ethylene oxide, propylene oxide, butylene oxide) to a diol containing a bisphenol backbone. The diol containing a bisphenol backbone is, for example, methylene bisphenol, ethylidene bisphenol, butylidene bisphenol, isopropylidene bisphenol, etc. The addition molar number of the alkylene oxide is preferably 1 to 10. The amino resin in component B can be selected from at least one of commercially available Cytec 216, Cytec 301, Cytec 303, Cytec 327, Cytec 325, Cytec 370, Cytec 385, Cytec 659, Cytec 683, Cytec 1156, Cytec 1123, Cytec MM-100, Ineos 717, Ineos 718, Ineos R747, Ineos R757, Ineos 917, Ineos MF927, Ineos MF984, Ineos MF985, Ineos MF986, Ineos MF988, Ineos M195, Ineos MR921, Ineos CE7103, Ineos CE8824, Aoshi OS 303-98, Aoshi OS 325-80, methylated amino resin 5717W, fully methylated amino resin MR603, MELCROSS-83, Changxing ETERMINO9411, ETERMINO9412; other amino resins can also be used.In this embodiment, the polyester backbone part, polyether backbone part and their mass ratio in the A-component polyurethane resin are selected according to actual requirements, and the specific amino resin in the B-component is selected, so that after the A-component and the B-component are mixed, an anti-shrinkage viscous liquid with a tensile strength ≥ 250 Mpa and an elongation at break ≥ 80% after curing is formed.

[0029] To enhance the performance of the anti-shrinkage viscous layer 120, the anti-shrinkage viscous liquid may further include a C filler component. The ratio of the A-component, B-component and C filler component is: (90-99):(1~5):(1~5). In this embodiment, 93:3:3 can be selected; the C filler component includes at least one of silica, aluminum hydroxide, alumina, talc, aluminum nitride, boron nitride, silicon carbide, barium sulfate, barium titanate, strontium titanate, boehmite, calcium carbonate, calcium silicate, mica, graphite, magnesium oxide, magnesium hydroxide, kaolin, starch, montmorillonite, titanium dioxide, zinc sulfide, calcium bicarbonate, calcium phosphate, calcium hydrogen phosphate, calcium sulfate, carbon black, graphite, multi-walled and single-walled carbon nanotubes, carbon nanofibers, polytetrafluoroethylene particles, polyurethane microparticles, rubber particles, polyamide microparticles, silicone particles, graphene, nanotube structures and antimony trioxide.

[0030] The support layer 110 is directly bonded to the metal layer 130 through the anti-shrinkage viscous layer 120 to form the current collector 100. The anti-shrinkage viscous layer 120 can be a semi-cured layer structure pre-formed from the anti-shrinkage viscous liquid, and is directly compounded with the support layer 110 and the metal layer 130; alternatively, the anti-shrinkage viscous liquid can be coated on the surface of the support layer 110 to form the anti-shrinkage viscous layer 120, and then further compounded with the metal layer 130.

[0031] In this embodiment, the aforementioned anti-shrinkage adhesive liquid or other existing anti-shrinkage viscous materials are selected, so that the tensile strength of the anti-shrinkage viscous layer 120 ≥ 250 Mpa and the elongation at break ≥ 80%. To improve the mechanical properties of the formed composite current collector 100, the tensile strength of the anti-shrinkage viscous layer 120 can be 280 Mpa to 400 Mpa, or a more specific tensile strength, such as, the tensile strength is 280~350 Mpa; the range of the adhesion between the anti-shrinkage viscous layer 120 and the support layer 110 is 3 N / 25 mm to 30 N / 25 mm; the range of the adhesion between the anti-shrinkage viscous layer 120 and the metal layer 130 is 3 N / 25 mm to 30 N / 25 mm, and can also be 3 N / 25 mm to 20 N / 25 mm; more preferably, the range of the adhesion between the anti-shrinkage viscous layer 120 and the metal layer 130 is 3 N / 25 mm to 15 N / 25 mm.

[0032] In addition to incorporating the C filler component before the formation of the anti-shrinkage adhesive layer 120 as described above, cavities for accommodating functional solid fillers can also be arranged inside during the formation of the anti-shrinkage adhesive layer 120; when using other materials in the prior art to form the anti-shrinkage adhesive layer 120, the performance can also be improved by reserving cavities and filling them with functional solid fillers. The anti-shrinkage adhesive layer 120 can be filled with functional solid fillers to further improve the performance of the anti-shrinkage adhesive layer 120 without affecting the thickness. The functional solid fillers include at least one of silica, aluminum hydroxide, alumina, talc powder, aluminum nitride, boron nitride, silicon carbide, barium sulfate, barium titanate, strontium titanate, boehmite, calcium carbonate, calcium silicate, mica, graphite, magnesium oxide, magnesium hydroxide, kaolin, starch, montmorillonite, titanium dioxide, zinc sulfide, calcium bicarbonate, calcium phosphate, calcium hydrogen phosphate, calcium sulfate, carbon black, graphite, multi-walled and single-walled carbon nanotubes, carbon nanofibers, polytetrafluoroethylene particles, polyurethane microparticles, rubber particles, polyamide microparticles, silicone particles, graphene, nanotube structures, and antimony trioxide.

[0033] In this embodiment, the thickness of the support layer 110 is 1.9 - 6 μm; the thickness of the anti-shrinkage adhesive layer 120 is 0.8 - 4 μm; the thickness of the metal layer 130 is 0.8 - 3.5 μm. Considering the thickness, performance, and metal consumption of the current collector 100, the thickness of the metal layer 130 can be 0.8 - 1.5 μm; more preferably, the thickness of the metal layer 130 is 1 - 1.5 μm. In this embodiment, the total thickness range of the current collector 100 is 6 - 12 μm. The support layer 110 is made of at least one of PET, PP, PI, PE, PVC, PBT, PC, PS, ABS, PA, PASF, PVDF, PEDOT, PANI, and PPy; the metal layer 130 is made of at least one of copper, aluminum, titanium, nickel, cadmium, iron, or silver. In this embodiment, the metal layer 130 is a copper layer. The metal layer 130 is a copper foil layer; and there are ≤ 5 pinholes per square meter on the copper foil layer, and the diameter of the pinholes ≤ 0.1 mm.

[0034] In addition to the basic hierarchical structure, the current collector 100 in this embodiment may further include a protective layer 140, such as Figure 2 as shown, the protective layer 140 is provided on the surface of the metal layer 130 away from the support layer 110; the protective layer 140 is formed of at least one material of chromium, tungsten, molybdenum, nickel, iron, titanium, niobium, zirconium, gold, silver, platinum, carbon, chromate compounds, silane compounds, and benzotriazole and its modified compounds. The thickness of the protective layer 140 is 0.01 - 0.15 μm.

[0035] In the current collector 100 formed in this embodiment, the surface roughness Ra of the metal layer 130 ≤ 0.3 μm; the surface dyne value of the metal layer 130 ≥ 46.

[0036] The thermal shrinkage rate of the anti-shrinkage adhesive layer 120 after being treated at 150°C for 30 minutes is ≤3%; the elongation rate of the current collector 100 is ≥3%. Further, the thermal shrinkage rate of the anti-shrinkage adhesive layer 120 after being treated at 150°C for 30 minutes is 0.9 - 2.5%. The surface sheet resistance of the current collector 100 is ≤23 mΩ. In this embodiment, whether it is the anti-shrinkage adhesive liquid formed by mixing the aforementioned Component A and Component B, or the anti-shrinkage adhesive liquid that meets the performance of the aforementioned anti-shrinkage adhesive layer 120 after curing using the existing technology; both are coated on a certain carrier to form the anti-shrinkage adhesive layer 120; therefore, the anti-shrinkage adhesive layer 120 is not produced by stretching on a certain length production line, but is directly coated and then cured, so its mechanical properties in the transverse and longitudinal directions are similar; although the test process is carried out based on the longitudinal length, in fact, its thermal shrinkage rate, tensile strength, and elongation at break are almost equal in the longitudinal and transverse directions, with an error of no more than 3%. The thermal shrinkage rate, elongation at break, and tensile strength of the anti-shrinkage adhesive layer 120 in this application should be understood as values that do not distinguish between the longitudinal and transverse directions, or can also be considered to represent the longitudinal and transverse values simultaneously. The thermal shrinkage rate of the anti-shrinkage adhesive layer 120 in this application is tested according to the JISC2151 standard. Example 2

[0037] Based on Example 1, in this embodiment, corresponding samples are prepared using common ordinary adhesive materials and adhesive materials with different curing shrinkage rates, and are divided into Group A: ordinary non-anti-shrinkage adhesive materials (curing shrinkage rate > 6%); Group B: adhesive materials with a curing shrinkage rate of 5%; Group C: anti-shrinkage adhesive materials that meet the performance requirements of Example 1 after curing, with a curing shrinkage rate of 2.8% (when using the anti-shrinkage adhesive liquid based on Component A and Component B, the original components and ratios can be adjusted to adjust the curing shrinkage rate); Group D: anti-shrinkage adhesive materials that meet the performance requirements of Example 1 after curing, with a curing shrinkage rate of 0.5%. Then, corresponding performance tests are carried out for each group.

[0038] Sample type / Test category Adhesive force between the support layer and the anti-shrinkage adhesive layer (N / 25mm) Adhesive force between the anti-shrinkage adhesive layer and the metal layer (N / 25mm) Group A 1.5 1.4 Group B 1.8 1.5 Group C 3.9 3.4 Group D 4.8 4.7

[0039] In the test results, for the samples in Group A and Group B, shrinkage conditions were observed, and there were voids or bubbles between the anti-shrinkage adhesive layer 120 and the support layer 110 and the metal layer 130, that is, the anti-shrinkage adhesive layer 120 was not closely attached to the metal layer 130; and the shrinkage in Group A was more severe than that in Group B, and the overall current collector 100 showed a tightly wrinkled state; while in Group C and Group D, no obvious shrinkage occurred, and no obvious bubbles or voids were observed. In terms of the adhesive force performance, based on the anti-shrinkage effect of the anti-shrinkage adhesive layer 120, the different layers in Group C and Group D were smoothly attached, and there was an obvious difference in the adhesive force compared with other groups; specifically, the adhesive force performance of Group C and Group D was excellent, and among them, Group D was the best. The adhesive effects of Group A and Group B were both poor. Example 3

[0040] Based on the manufacturing process of Example 1, in this example, the anti-shrinkage adhesive layer 120 was separately coated on the release film, and an adhesive layer with a thickness of 4 μm was made. Five groups of anti-shrinkage adhesive layers 120 were made with different weight ratio of component A, component B, and component C. The performance test results are shown in the following table (where the peel strength was tested after one side was laminated with the metal layer 130).

[0041] Performance test Unit ① Test results (A∶B ∶C = 90∶1∶1) ② Test results (A∶B ∶C = 93∶3∶3) ③ Test results (A∶B ∶C = 95∶5∶5) ④ Test results (A∶B∶C = 80∶5∶5) ⑤ Test results (A∶B∶C = 100∶0∶2.5) Average thickness μm 3.98 4.05 4.12 4.06 3.95 Tensile strength Mpa 278 298 313 254 220 Elongation at break % 95 97 110 84 75 Peel strength / Adhesive force N / 25mm 5.075 5.375 5.475 4.925 1.575 Thermal shrinkage rate (150℃×30min) % 1.82 1.11 0.98 1.03 1.12

[0042] The results show that groups ① to ④ all have good performance test results and meet the requirements as the support layer 110 of the composite current collector 100. Compared with groups ① to ③, group ④ shows a decrease in tensile strength and elongation at break, and the adhesion also decreases. Group ⑤ shows weak adhesion to the metal layer 130, and the attachment of the metal layer 130 is unstable; moreover, the mechanical properties, tensile strength, etc. are also significantly weaker than those of groups ① to ④. Example 4

[0043] In this example, composite current collectors 100 were obtained with different thicknesses of the support layer 110, anti-shrinkage adhesive layer 120, and metal layer 130, and corresponding performance tests were carried out. The test results are shown in the following table.

[0044] Including the following sample groups with different thickness selections: a. Metal layer 1 μm, anti-shrinkage adhesive layer 2.3 μm, support layer 1.9 μm; b. Metal layer 0.8 μm, anti-shrinkage adhesive layer 1.5 μm, support layer 3 μm; c. Metal layer 1.3 μm, anti-shrinkage adhesive layer 0.8 μm, support layer 4.5 μm; d. Metal layer 1.5 μm, anti-shrinkage adhesive layer 0.3 μm, support layer 5 μm; e. Metal layer 3.6 μm, anti-shrinkage adhesive layer 0.5 μm, support layer 1.5 μm.

[0045] In this example, the metal layer 130 is made of a copper foil layer; the anti-shrinkage adhesive layer 120 can be formed by using the anti-shrinkage adhesive liquid with the ratio of A∶B ∶C = 93∶3∶3 as described above; in addition, other existing anti-shrinkage adhesive materials can also be used.

[0046] Performance test Unit a b c d e Average total thickness μm 8.5 7.6 8.7 8.6 9.7 Tensile strength Mpa 260 276 289 289 170 Elongation % 3.5 3.6 3.7 3.3 2.8

[0047] The results show that overall, the current collector 100 with an anti-shrinkage adhesive layer 120 of a certain thickness based on this application has excellent mechanical properties. In terms of performance, the anti-shrinkage adhesive layer 120 can significantly improve the tensile strength and elongation rate in multiple aspects. The metal layer 130 also has an obvious influence at least on factors such as tensile strength. It should be noted that the cooperation of the anti-shrinkage adhesive layer 120 with the support layer 110 and the metal layer 130 can synergistically ensure the comprehensive excellent performance of the corresponding current collector 100. Example 5

[0048] This example discloses a battery, including the negative electrode current collector 100 described in the foregoing Example 1. The battery in this example has a high energy density, the bonding between different layers is tight, and the performance is stable. Example 6

[0049] This example discloses the application of the negative electrode current collector 100 of Example 1 or the battery described in Example 5 in a power vehicle.

[0050] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the technical solutions of the present invention, rather than limitations on the specific implementation manners of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the claims of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A current collector, characterized in that, It includes a support layer, a shrinkage-resistant adhesive layer, and a metal layer; the shrinkage-resistant adhesive layers are arranged on both sides of the support; a metal layer is provided on the side of the shrinkage-resistant adhesive layer away from the support layer.

2. The current collector according to claim 1, characterized in that, The tensile strength of the shrinkage-resistant adhesive layer is ≥250 Mpa; the elongation at break is ≥80%.

3. The current collector according to claim 1, wherein, The bonding strength between the shrinkage-resistant adhesive layer and the support layer ranges from 3 N / 25 mm to 30 N / 25 mm; the bonding strength between the shrinkage-resistant adhesive layer and the metal layer ranges from 3 N / 25 mm to 30 N / 25 mm.

4. The current collector according to claim 1, wherein, The thickness of the support layer is 1.9 - 6 μm; the thickness of the shrinkage-resistant adhesive layer is 0.8 - 4 μm; the thickness of the metal layer is 0.8 - 3.5 μm.

5. The current collector according to any one of claims 1 to 4, characterized in that, The support layer is made of at least one of PET, PP, PI, PE, PVC, PBT, PC, PS, ABS, PA, PASF, PVDF, PEDOT, PANI, and PPy.

6. The current collector according to any one of claims 1 to 4, characterized in that The metal layer is at least one of copper, aluminum, titanium, nickel, cadmium, iron, and silver.

7. The current collector according to any one of claims 1 to 4, characterized in that It further includes a protective layer, and the protective layer is provided on the side of the metal layer away from the support layer; further, the protective layer is formed of at least one material of chromium, tungsten, molybdenum, nickel, iron, titanium, niobium, zirconium, gold, silver, platinum, carbon, chromate compounds, silane compounds, and benzotriazole and its modified compounds.

8. A battery, characterized in that, It includes the current collector according to any one of claims 1 - 7.

9. An application of the current collector according to any one of claims 1 - 7 or the battery according to claim 8 in a power vehicle.

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