Negative current collector, battery and power automobile

Abstract

The utility model discloses a negative electrode current collector, a battery and a power automobile, the negative electrode current collector comprises a supporting layer, and at least one side of the supporting layer is sequentially provided with a surface treatment layer, a bonding layer and a metal layer in the direction far away from the supporting layer; the surface treatment layer endows the supporting layer with surface active groups so as to improve the bonding force between the supporting layer and the bonding layer. The surface of the supporting layer is treated through the surface treatment layer, so that the surface performance can be remarkably improved, and the defect of the supporting layer on the adhesion strength is overcome; and the surface treatment basically has no influence on the thickness, so that the advantages of the current collector can be brought into full play while the stability is improved. The surface treatment of the supporting layer is matched with the bonding layer, so that the metal layer and the supporting layer are kept in a stable combination state. The current collector is stable in hierarchical structure, the metal layer and the supporting layer are tightly combined, and the conditions of separation and the like are not prone to occurring; the service life and the performance can be improved, so that products such as batteries which can be used for a long time can be obtained.

Description

Technical Field

[0001] The utility model relates to the technical field of battery materials, and more specifically, to a negative electrode current collector, a battery and a power vehicle. 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 a polymer insulating resin such as PET (polyethylene terephthalate), PP (polypropylene), PI (polyimide), etc. as a film substrate. Then, metal layers such as copper foil layers are made on both sides of the film substrate by magnetron sputtering, vacuum evaporation, water electroplating, or a combination of multiple processes to form a composite current collector sandwich structure. Compared with metal current collectors formed by traditional all-metal materials, composite current collectors have the advantages of high energy density and low metal consumption. Therefore, the replacement of traditional metal current collectors by composite current collectors has become the current development trend of batteries.

[0003] Although the composite current collector has certain advantages over the traditional all-metal current collector, it still has some shortcomings; specifically, in the coordination between the metal layer and the base film of the composite current collector, the poor adhesion of the metal layer on the base film often affects the performance and life of the composite current collector. Therefore, there is still a need for improvement in how to enhance the coordination between the base film and the metal layer. To this end, the prior art proposes a method for enhancing the bonding between the base film and the metal layer, that is, providing an adhesive layer between the base film and the metal layer, and enhancing the bonding between the base film and the metal layer through the adhesive layer. However, it is worth noting that due to the different materials and surface properties of the base film and the metal layer, although the adhesive layer provided between the base film and the metal layer provides a certain degree of viscosity, the same surface of the adhesive layer cannot take into account both sides so that both sides have considerable bonding strength, which still easily leads to detachment of the base film or the metal layer.

[0004] The prior art urgently needs a composite current collector to overcome the instability of the bonding between the support layer and the metal layer in the prior art and ensure a firm bonding between the support layer and the metal layer. Utility Model Content

[0005] The present invention aims to overcome at least one of the shortcomings of the above-mentioned prior art and provides a negative electrode current collector, a battery and a power vehicle. The surface-treated support layer in the negative electrode current collector of the present application can be tightly combined with the adhesive layer. The surface treatment and the adhesive layer can take into account the different surface characteristics of the original support layer and the metal layer, achieve tight combination of the support layer and each connection position of the metal layer, and ensure a stable bond between the support layer and the metal layer.

[0006] The technical solution adopted by the utility model is a negative electrode current collector comprising a support layer, with a surface treatment layer, an adhesive layer, and a metal layer sequentially disposed on at least one side of the support layer in a direction away from the support layer. The surface treatment layer imparts surface active groups to the support layer to enhance the bonding between the support layer and the adhesive layer. Furthermore, the surface treatment layer, adhesive layer, and metal layer can be sequentially disposed on both sides. The surface treatment layer is a layered structure formed on the surface of the support layer by treating the support layer with a surface treatment agent, and is located between the composite current collector support layer and the adhesive layer. Compared to conventional adhesive layer structures that rely on wettability and surface tension requirements to provide good adhesion, surface treatment agents at least react and bond with the surface functional groups of the support layer substrate to form a bond or form van der Waals forces with the polar groups on the surface of the support layer substrate to form a bond. This can effectively improve the adhesion effect limitations caused by the low surface tension of the support layer. The resulting surface treatment coating of the support layer imparts surface active groups to the support layer to improve the adhesion between the support layer and the adhesive layer. After the surface treatment agent treats the support layer surface, the surface properties, including the interfacial surface tension of the adhesive layer, are improved. The adhesive layer can closely bond with the surface treatment layer on the support layer, achieving a tight bond with the support layer. Due to the high surface tension of the metal layer, the adhesive layer easily bonds to the metal layer, that is, the metal layer and the adhesive layer also have strong adhesion. Therefore, through the surface treatment of the support layer and the connection of the adhesive layer, a stable bond between the support layer and the metal layer is achieved. The negative electrode current collector of the present application is pre-treated to improve the surface performance of the support layer. The surface treatment layer forms a chemical bridge between the support layer substrate and the adhesive layer, and cooperates with the adhesive layer to take into account the bonding of the support layer and the metal layer on both sides, overcoming the problem of difficulty in close bonding caused by the low surface tension of the support layer and the poor bonding effect of the separate adhesive layer due to the difference in surface performance of the support layer and the metal layer; the metal layer is tightly bonded to the support layer substrate, thereby improving the performance and stability of the corresponding negative electrode current collector.

[0007] Furthermore, the surface tension dyne value of the surface treatment layer formed by the surface treatment agent is ≥50; the dyne value of the metal layer is ≥46. In one embodiment of the present application, the current collector can be made by the following steps: the surface treatment agent is applied to the surface of the support layer by various methods such as immersion and roller coating, and then an adhesive liquid is applied on this basis to form an adhesive layer. The adhesive liquid is easy to wet and spread as much as possible on the support layer after the surface treatment, which is conducive to the adhesive liquid fully bonding with the support layer through the surface active groups of the support layer imparted by the surface treatment; in one embodiment, when the adhesive liquid is in a solidified or semi-solidified state after coating, it can be directly bonded to the metal layer for compounding. At this time, since the surface tension of the adhesive layer is less than that of the metal layer, the side of the adhesive layer close to the metal layer is also easy to wet and spread on the surface of the metal layer; thus, the adhesive layer has good adhesion to the support layer and the metal layer on both sides. The surface dyne value parameter is measured using a dyne pen. The surface dyne value of the surface treatment layer and the surface dyne value of the metal layer in the composite current collector of the present application are conducive to stable adhesion with the adhesive layer; the surface dyne value of the metal layer is also conducive to the coating of other layers or active substances on the metal layer.

[0008] Furthermore, the surface tension difference between the surface treatment agent / surface treatment layer and the adhesive layer ranges from 3 to 15 mN / m; further, the surface tension difference between the surface treatment agent / surface treatment layer and the adhesive layer ranges from 3 to 10 mN / m; further, the surface treatment layer is formed by applying the surface treatment agent on the support layer and curing; the adhesive layer is formed by applying the adhesive liquid on the surface treatment layer and curing; further, when the surface treatment agent is cured to a formed but not completely cured state, the adhesive liquid can be applied to the surface treatment layer; since the surface tension of the surface treatment agent is similar to that of the adhesive liquid, the two have good compatibility at this time, and will appear in a blended state at the interface to form a stable and mutually bonded interface layer, and the surface treatment layer and the adhesive layer tend to form an integrated structure that is difficult to separate; thereby significantly ensuring the stable bonding between the surface-treated support layer and the adhesive layer. The metal layer is directly bonded to the surface of the adhesive layer away from the support layer to form a composite; in one or more embodiments, the surface treatment agent is an adhesion promoter, specifically a polyurethane polymer material; the adhesive liquid is a viscous liquid material whose surface tension after curing is less than the surface tension of the surface treatment layer and the surface tension of the metal layer. In addition to the adhesion promoter, the surface treatment agent described in this application can also be formed of other materials, such as a fluoroacid mainly containing 4 or more fluorine atoms and one or more elements selected from titanium, zirconium, silicon, aluminum, and boron, including fluorotitanic acid, fluorozirconic acid, etc.; or a compound having at least one reactive functional group selected from amino, epoxy, vinyl, and mercapto groups containing active hydrogen, including r-aminopropyltriethoxysilane, r-aminopropyltrimethoxysilane, etc.

[0009] Furthermore, the adhesive layer has insulation, viscosity, tensile strength, and extensibility; the adhesive layer is formed by coating an adhesive liquid on a surface-treated support layer and curing it; the metal layer is directly bonded to the surface of the adhesive layer away from the support layer to form a composite; the surface-treated support layer is directly bonded to the metal layer through the adhesive layer to form a negative electrode current collector. Compared to forming a metal layer on a supporting structure base film by magnetron sputtering or water electroplating on the surface of the support layer, the present application utilizes the adhesive properties of the adhesive layer to directly bond the metal layer on the adhesive layer, thereby forming a 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 easy to achieve mass production, and overcomes the problem that the existing technology is difficult to mass produce. In addition to the aforementioned method of sequentially coating to form layers, the adhesive layer can be a pre-formed semi-cured layer structure, which is directly composited with a support layer and a metal layer covered with a surface treatment layer.

[0010] Furthermore, the thickness of the support layer ranges from 1.9 to 6 μm; the thickness of the surface treatment layer ranges from 0.01 to 0.5 μm; the thickness of the adhesive layer ranges from 0.5 to 3 μm; and the thickness of the metal layer ranges from 0.8 to 3.5 μm. Furthermore, the thickness of the metal layer ranges from 0.8 to 1.5 μm; and even more preferably, the thickness of the metal layer ranges from 1 to 1.5 μm. In one embodiment, the surface treatment agent is applied to the support layer by immersion or roller coating, and the surface of the support layer is treated using nano-scale processing combined with the surface treatment agent. Since the surface treatment agent / surface treatment layer described in this application mainly functions to improve the surface of the support layer and thereby enhance the bonding effect between the support layer and the adhesive layer, rather than being a glue layer whose main function is to provide adhesiveness, it only needs to be in contact with the surface of the support layer to basically achieve the corresponding function. The thickness of the surface treatment layer formed can range from 0.01 to 0.5 μm, which has a negligible effect on the thickness of the current collector and is also conducive to ensuring the advantages of the composite current collector; and this thickness is sufficient to cover the support layer and improve the surface performance. Within the overall thickness range, it meets the requirements of common lithium battery negative electrode current collectors; when the thickness is thinner, it is beneficial to reduce the material cost of the corresponding battery and increase the battery energy density by thinning and reducing weight. The thickness range of the metal layer can ensure a certain degree of toughness and rigidity, meet the overall elongation at break of the current collector, make the current collector have a high tensile strength, and meet the expansion problem of the positive and negative electrode materials of the battery during charging and discharging. It can also ensure the current transmission of the battery and the stable welding of the electrode tabs.

[0011] Furthermore, the tensile strength of the adhesive layer is ≥250Mpa; the elongation at break is ≥80%. The 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. Furthermore, the tensile strength of the adhesive layer is 280Mpa~400Mpa; further, the tensile strength of the adhesive layer is 280~350Mpa; further, the bonding force between the adhesive layer and the metal layer is in the range of 3N / 25mm~30N / 25mm; further, the bonding force between the adhesive layer and the metal layer is in the range of 3N / 25mm~20N / 25mm; further, the bonding force between the adhesive layer and the metal layer is in the range of 3N / 25mm~15N / 25mm. In addition to its adhesive properties, the 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. By utilizing its mechanical properties, the toughness and safety of the current collector can be further improved on the basis of the support layer substrate.

[0012] Furthermore, the adhesive layer contains a cavity for accommodating a functional solid filler. The adhesive layer can be filled with a functional solid filler to further improve the performance of the insulating adhesive layer without affecting thickness. Furthermore, the functional solid filler includes at least one of silicon dioxide, aluminum hydroxide, aluminum oxide, 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, organosilicon particles, graphene, nanotube structures, and antimony trioxide. For example, by filling the adhesive layer cavity with a flame-retardant filler, the current collector can be made flame-retardant, further improving safety.

[0013] Furthermore, it also includes a protective layer, which is arranged on the surface of the metal layer away from the support layer; the protective layer is formed of at least one material selected from chromium, tungsten, molybdenum, nickel, iron, titanium, niobium, zirconium, gold, silver, platinum, carbon, chromate compounds, silane compounds, nitrogen compounds, and benzotriazole and its modified compounds. On the basis of the basic composite current collector structure, a protective layer structure can also be added. The protective layer can prevent the conductive layer of the current collector from chemical corrosion or oxidation, and can also enhance the mechanical strength of the current collector, and can improve the current flow capacity of the current collector and the electrode. Furthermore, the thickness of the protective layer is 0.01 to 0.15 μm; it is convenient to provide the protective layer function while having almost no impact on the overall current collector thickness.

[0014] Furthermore, the metal layer is at least one of copper, aluminum, titanium, nickel, cadmium, iron, and silver. Furthermore, the metal layer is a copper layer. The metal layer is a copper foil layer; the number of pinholes on the copper foil layer is ≤5 / ㎡, and the pinhole diameter is ≤0.1mm.

[0015] Furthermore, 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. Specifically, the support layer is made of at least one of PET (polyethylene terephthalate), PP (polypropylene), PI (polyimide), PE (polyethylene), PVC (polyvinyl chloride), PBT (polybutylene terephthalate), PC (polycarbonate), PS (polystyrene), ABS (terpolymer of acrylonitrile (A)-butadiene (B)-styrene (S)), PA (polyamide), PASF (polyarylsulfone), PVDF (polyvinylidene fluoride), PEDOT (poly(3,4-ethylenedioxythiophene), PANI (polyaniline), and PPy (polypyrrole).

[0016] Furthermore, the surface roughness of the metal layer Ra≤0.3μm; however, the metal layer also has a certain surface roughness, which, in addition to directly improving the conductive performance, can promote the formation of a mechanical bite interface between the metal layer and the adhesive layer, thereby enhancing the bonding between the metal layer and the adhesive layer.

[0017] Furthermore, the thermal shrinkage of the adhesive layer after treatment at 150°C for 30 minutes is ≤3%; further, the elongation of the composite current collector is ≥3%. Furthermore, the thermal shrinkage of the insulating adhesive layer after treatment at 150°C for 30 minutes is 0.9-2.5%. Furthermore, the surface resistance of the composite current collector is ≤23mΩ. The adhesive layer of this application is not produced by stretching on a specific length production line, but is directly coated and then cured, so its transverse and longitudinal mechanical properties are similar; although the testing process is based on the longitudinal length, the actual thermal shrinkage, 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, elongation at break, and tensile strength of the 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. The thermal shrinkage of the adhesive layer of this application is tested in accordance with the JISC2151 specification. The adhesive layer of the present application has a heat shrinkage rate of ≤3%, has excellent heat resistance and thermal stability, and is beneficial to improving the safety of batteries.

[0018] Another object of the present application is to provide a battery comprising the aforementioned negative electrode current collector. The negative electrode current collector of the present application is advantageous for mass production, and is also advantageous for forming batteries with high energy density and stable performance, thereby promoting the development of corresponding negative electrode current collector application products.

[0019] Another object of the present application is to provide a power vehicle, comprising the aforementioned negative electrode current collector or the aforementioned battery.

[0020] Compared with the prior art, the beneficial effects of the present application are as follows: by treating the surface of the support layer through the surface treatment layer, the surface properties can be significantly improved, thereby overcoming the defects of the support layer in adhesion strength; the layered structure formed by the surface treatment agent has an almost negligible thickness and has basically no effect on the thickness of the overall current collector. While improving the surface properties, it minimizes the impact on the thickness and energy density of the current collector, improves stability and facilitates full play of the advantages of the current collector. The surface treatment of the support layer cooperates with the adhesive layer to enable the metal layer and the support layer to maintain a stable bonding state. It overcomes the problems of low surface tension of common support layer materials and poor bonding effect of a separate adhesive layer caused by large differences in surface properties of the support layer and the metal layer, and solves the problem of stable bonding that has a greater impact on the stability of the current collector in the prior art. And on the basis of using the surface treatment layer and the adhesive layer, the characteristics of the similar surface tension of the liquid of the two layer structures are utilized, combined with the present application to cover the solidified or semi-solidified state in sequence, so that the formed surface treatment layer and the adhesive layer tend to form an integrated structure, significantly improving the overall bonding stability. The current collector of the present application has a stable hierarchical structure, and the metal layer and the support layer are tightly bonded, making it less likely for detachment to occur; this is beneficial for improving service life and performance, thereby obtaining products such as batteries that can be used for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the hierarchical structure of the composite current collector of this application;

[0022] Figure 2 This is a schematic diagram of the hierarchical structure of the composite current collector containing a protective layer in this application;

[0023] Description of the drawings: composite current collector 100 , support layer 110 , surface treatment layer 120 , adhesive layer 130 , metal layer 140 , protective layer 150 . DETAILED DESCRIPTION

[0024] The drawings in this utility model are for illustrative purposes only and are not to be construed as limiting the scope of this utility model. To better illustrate the following embodiments, some components in the drawings may be omitted, enlarged, or reduced in size, and do not represent the actual dimensions of the products. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted from the drawings.

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are part of the embodiments of the present invention, rather than all of the 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 in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0026] Example 1

[0027] This embodiment discloses a negative electrode current collector 100, comprising a support layer 110, wherein at least one side of the support layer 110 is provided with a surface treatment layer 120, an adhesive layer 130, and a metal layer 140 in sequence in a direction away from the support layer 110; the surface treatment layer 120 imparts surface active groups to the support layer 110 to improve the bonding force between the support layer 110 and the adhesive layer 130. Furthermore, the surface treatment layer 120, the adhesive layer 130, and the metal layer 140 may be provided in sequence on both sides, such as Figure 1 As shown. The surface treatment layer 120 is a hierarchical structure formed on the surface of the support layer 110 by treating the support layer 110 with a surface treatment agent, and is located between the support layer 110 and the adhesive layer 130 of the composite current collector 100. In this embodiment, the current collector 100 can be made by the following steps, wherein the surface treatment agent is applied to the surface of the support layer 110 in a variety of ways such as immersion and roller coating, and then an adhesive liquid is coated on this basis to solidify to form the adhesive layer 130; the metal layer 140 is directly bonded to the surface of the adhesive layer 130 away from the support layer 110 to form a composite. In addition to the surface treatment agent and adhesive liquid specifically referred to in this application, other corresponding existing surface treatments and adhesive liquids can be selected according to the materials of the support layer 110 and the metal layer 140; the negative electrode current collector 100 formed in this embodiment has a dyne value of ≥50 for the surface treatment agent / surface treatment layer 120; and a dyne value of ≥46 for the metal layer 140.

[0028] The surface tension difference between the surface treatment agent / surface treatment layer 120 and the adhesive layer 130 is ≤15mN / m, and the specific surface tension difference between the surface treatment agent / surface treatment layer 120 and the adhesive layer 130 is preferably in the range of 3 to 15mN / m. In order to improve the effect, the material can be selected so that the surface tension difference between the surface treatment agent / surface treatment layer 120 and the adhesive layer 130 is in the range of 3 to 10mN / m, which is similar but not completely the same. The surface treatment layer 120 is formed by curing the surface treatment agent on the support layer 110; the adhesive layer 130 is formed by applying an adhesive liquid to the surface treatment layer 120 and curing it. The adhesive liquid can be applied to the adhesive layer 130 when the surface treatment agent has cured to a shaped but not fully cured state. Because the surface tension of the surface treatment agent is similar to that of the adhesive liquid, the two are highly compatible and blend at the interface, forming a stable and mutually bonded interface layer. The surface treatment layer 120 and the adhesive layer 130 tend to form a single, difficult-to-separate structure, thereby significantly ensuring a stable bond between the surface-treated support layer 110 and the adhesive layer 130. The metal layer 140 is directly bonded to the surface of the adhesive layer 130 away from the support layer 110 for composite bonding. In this embodiment, the surface treatment agent is an adhesion promoter, formed of a polyurethane polymer material, specifically the water-based primer ESD56 from Shaanxi Oriental Aerospace Science and Technology Co., Ltd. The adhesive liquid is preferably formed of a viscous liquid material whose surface tension after curing is less than the surface tension of the surface-treated support layer 110 and the surface tension of the metal layer 140. In addition, in addition to the adhesion promoter, the surface treatment agent may also be formed of other materials that can impart active groups on the surface of the support layer 110 that facilitate adhesion to the adhesive layer 130 .

[0029] Based on the same preparation process and conditions, the present application also uses the following surface treatment agents: Group (a): Fluorinated acids primarily containing four or more fluorine atoms and one or more elements selected from titanium, zirconium, silicon, aluminum, and boron; specifically, fluorotitanic acid was selected during implementation; and Group (b): Compounds having at least one reactive functional group selected from amino, epoxy, vinyl, and mercapto groups containing active hydrogen; specifically, r-aminopropyltrimethoxysilane was selected during implementation. The aforementioned and subsequent example test processes were conducted, and the results showed that both Groups (a) and (b) were able to achieve the purpose of the surface treatment support layer 110 of the present application, and the resulting negative electrode current collector 100 had correspondingly excellent bonding stability. Similar tests were conducted, and it was found that both Groups (a) and (b) achieved similar test results to those obtained when the surface treatment layer 120 was formed using an adhesion promoter.

[0030] In this embodiment, the surface treatment agent is formed by an adhesion promoter made of a polyurethane polymer material; the adhesive layer 130 is formed by curing an adhesive liquid, and the adhesive liquid includes a mixed component A and a component B, wherein the component A is at least one of a polyurethane resin, an acrylic resin, an epoxy resin, a polyester resin, a polyimide, a silicone polymer and a modified compound thereof; the liquid B is at least one of an amino resin, an isocyanate, an aziridine cross-linking agent, a carbodiimide, a silane coupling agent and a silicone tackifier; wherein the weight ratio of component A to component B is: (90-99): (1-5); in this embodiment, 93:3 can be selected.

[0031] The polyurethane resin described in component A of this embodiment has a polyester backbone portion and a polyether backbone portion, and the mass ratio of the polyester backbone portion to the polyether backbone portion in the polyurethane resin is in the range of (1:9) to (5:5); the polyester backbone can be formed by a polyester polyol compound, which is formed by low molecular weight polyols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,2-butanediol, Compounds produced by reacting bisphenol A, 1,3-butanediol, 1,4-butanediol, 3-methylpentanediol, 1,6-hexanediol, hydrogenated bisphenol A, trimethylolpropane, and glycerol with polybasic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrophthalic acid, methylene-terminated tetrahydrophthalic acid, and hexahydrophthalic acid have an ester structure and terminal hydroxyl groups. The polyether backbone can be formed from a polyether polyol, preferably a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms (such as ethylene oxide, propylene oxide, and butylene oxide) to a diol containing a bisphenol backbone. Examples of the diol containing a bisphenol backbone include methylene bisphenol, ethylidene bisphenol, butylidene bisphenol, and isopropylidene bisphenol. The number of added moles of alkylene oxide is preferably 1 to 10. The amino resin in component B can be selected from 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, OS 303-98, OS At least one of 325-80, methylated amino resin 5717W, fully methylated amino resin MR603, MELCROSS-83, Changxing ETERMINO 9411, and ETERMINO 9412; other amino resins may also be used. In this embodiment, the polyester backbone and polyether backbone components of the polyurethane resin in component A, and their mass ratio, are selected based on actual needs. The amino resin in component B is also selected so that, after mixing, components A and B form an insulating adhesive having a tensile strength ≥ 250 MPa and an elongation at break ≥ 80%.

[0032] The adhesive layer 130 formed by this adhesive liquid formulation exhibits insulation, adhesion, tensile strength, and extensibility. Adhesive layer 130 not only serves as an adhesive layer but also possesses strong mechanical properties, including tensile strength and elongation at break. Its location between support layer 110 and metal layer 140 enhances the mechanical properties of the overall current collector 100, further improving the toughness and safety of the current collector 100 on the basis of the support layer 110 substrate. The adhesive layer 130 has a tensile strength of ≥250 MPa and an elongation at break of ≥80%. To enhance the corresponding mechanical properties, the ratio of components A and B can be adjusted within a range such that the tensile strength of the adhesive layer 130 is 280 MPa to 400 MPa; more preferably, the tensile strength of the adhesive layer 130 is 280 MPa to 350 MPa; the bonding force between the adhesive layer 130 and the metal layer 140 is in the range of 3 N / 25 mm to 30 N / 25 mm; to enhance the bonding effect, the ratio of components A and B can be adjusted within a range such that the bonding force between the adhesive layer 130 and the metal layer 140 is in the range of 3 N / 25 mm to 20 N / 25 mm; more preferably, the bonding force between the adhesive layer 130 and the metal layer 140 is in the range of 3 N / 25 mm to 15 N / 25 mm. In addition to the above-mentioned surface treatment agent and adhesive liquid, this embodiment may also employ other existing surface treatment agents and adhesive liquids that meet the aforementioned performance requirements.

[0033] In this embodiment, a cavity is reserved within the adhesive layer 130 for accommodating a functional solid filler. If the adhesive layer 130 is formed using the aforementioned adhesive liquid, the cavity can be formed before the adhesive liquid fully solidifies. The adhesive layer 130 can be filled with a functional solid filler to further improve the performance of the insulating adhesive layer 130 without affecting its thickness. Furthermore, the functional solid filler includes at least one of silica, aluminum hydroxide, aluminum oxide, 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, organosilicon particles, graphene, nanotube structures, and antimony trioxide. For example, by using the flame retardant filler therein to fill the cavity of the adhesive layer 130, the current collector 100 can have flame retardant properties, further improving safety.

[0034] Regarding the aforementioned method of bonding component A and component B to form the bonding layer 130, in addition to pre-forming the cavity, a filler component C may be added to the bonding liquid, that is, the bonding liquid also includes component C, wherein the ratio of component A, component B, and filler component C is: (90-99):(1-5):(1-5), and in this embodiment, 93:3:3 may be selected; the filler component C includes at least one of silicon dioxide, aluminum hydroxide, aluminum oxide, 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 particles, rubber particles, polyamide particles, silicone particles, graphene, nanotube structure, and antimony trioxide.

[0035] In this embodiment, the thickness of the support layer 110 ranges from 1.9 to 6 μm; the thickness of the surface treatment layer 120 ranges from 0.01 to 0.5 μm; the thickness of the adhesive layer 130 ranges from 0.5 to 3 μm; and the thickness of the metal layer 140 ranges from 0.8 to 3.5 μm. To balance the thickness and performance of the current collector 100, the thickness of the metal layer 140 is preferably in the range of 0.8 to 1.5 μm, and more preferably in the range of 1 to 1.5 μm.

[0036] In order to improve the stability of the current collector 100, a protective layer 150 may be provided on the side of the metal layer 140 away from the support layer 110. Figure 2 As shown, protective layer 150 can be formed of at least one material selected from the group consisting of chromium, tungsten, molybdenum, nickel, iron, titanium, niobium, zirconium, gold, silver, platinum, carbon, chromate compounds, silane compounds, nitrogen compounds, and modified benzotriazole. Protective layer 150 has a thickness of 0.01 to 0.15 μm, ensuring that the protective layer 150 performs its function while maintaining minimal impact on the overall thickness of current collector 100.

[0037] In this embodiment, 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.

[0038] The metal layer 140 can be at least one of copper, aluminum, titanium, nickel, cadmium, iron, or silver. In this embodiment, the metal layer 140 is a copper foil layer; the number of pinholes on the copper foil layer is ≤5 / ㎡, and the pinhole diameter is ≤0.1mm.

[0039] The surface roughness of the metal layer 140 Ra≤0.3μm; when the metal layer 140 has a certain surface roughness, in addition to directly improving the conductive performance, it can further promote the formation of a mechanical bite interface between the metal layer 140 and the insulating adhesive layer 130, thereby enhancing the bonding between the metal layer 140 and the insulating adhesive layer 130.

[0040] Furthermore, the adhesive layer 130 in this embodiment exhibits a thermal shrinkage of ≤3% after treatment at 150°C for 30 minutes, demonstrating excellent heat resistance and thermal stability, thereby enhancing battery safety. The composite current collector 100 exhibits an elongation of ≥3%. Specifically, the insulating adhesive layer 130 exhibits a thermal shrinkage of 0.9-2.5% after treatment at 150°C for 30 minutes. The composite current collector 100 exhibits a surface resistance of ≤23 mΩ.

[0041] Example 2

[0042] In this embodiment, based on the manufacturing process of Example 1, an adhesive layer 130 was separately coated on the release film to produce an adhesive layer 130 with a thickness of 4 μm. Five sets of adhesive layers 130 were produced using different weight ratios of component A, component B, and component C. The performance test results are shown in the following table (wherein, the peel strength is based on the test conducted after the metal layer 140 was laminated on one side):

[0043]

[0044] The results show that groups 1 through 4 all exhibit good performance test results, meeting the requirements for use as the support layer 110 of the composite current collector 100. Compared to groups 1 through 3, group 4 exhibits reduced tensile strength, elongation at break, and decreased adhesion. Group 5 exhibits weak adhesion to the metal layer 140, resulting in unstable attachment of the metal layer 140. Its mechanical properties and tensile strength are also significantly weaker than those of groups 1 through 4.

[0045] Example 3

[0046] In this embodiment, based on the production process and production conditions described in Example 1, the same materials are used to obtain a composite current collector 100 with different thicknesses of the support layer 110, the surface treatment layer 120, the adhesive layer 130, and the metal layer 140, and corresponding performance tests are carried out. The test results are shown in the following table.

[0047] Includes the following sample groups with different thickness selections:

[0048] a. Metal layer 1μm, adhesive layer 0.5μm, surface treatment layer 0.5μm, support layer 2.5μm;

[0049] b. Metal layer 1.2 μm, adhesive layer 2.7 μm, surface treatment layer 0 μm, support layer 3.8 μm;

[0050] c. Metal layer 1.2 μm, adhesive layer 0.3 μm, surface treatment layer 0 μm, support layer 3.5 μm;

[0051] d. Metal layer 1.2 μm, adhesive layer 2.7 μm, surface treatment layer 0.35 μm, support layer 3 μm;

[0052] e. Metal layer 0.8 μm, adhesive layer 1.5 μm, surface treatment layer 0.02 μm, support layer 4.5 μm;

[0053] f, metal layer 1.5μm, adhesive layer 0.3μm, surface treatment layer 0.45μm, support layer 5μm;

[0054] g. Metal layer 3.6 μm, adhesive layer 3.2 μm, surface treatment layer 0.10 μm, support layer 1.5 μm.

[0055] In this embodiment, the metal layer 140 is a copper foil layer; the adhesive layer 130 can be made of the insulating adhesive liquid formed by the aforementioned A:B:C=93:3:3 ratio; in addition, other existing adhesive materials (such as a mixture of polyester fiber and adhesive fiber) can also be used.

[0056]

[0057] The test results show that, since the thickness of the surface treatment layer 120 is almost negligible, the tensile strength and elongation properties of the current collector 100 are mainly affected by the thickness of the metal layer 140, the adhesive layer 130 and the support layer 110; and in terms of bonding strength, the surface-treated support layer 110 combined with the adhesive layer 130 with a certain thickness or above has a very significant bonding advantage; although the adhesive layer 130 alone can provide a certain degree of bonding strength, the difference is still quite significant compared with the group with the surface-treated support layer 110; surface treatment can significantly improve the bonding effect of the adhesive layer 130.

[0058] Example 4

[0059] This embodiment discloses a battery, comprising the negative electrode current collector 100 described in the aforementioned embodiment 1. The battery of this embodiment has high energy density and stable performance.

[0060] Example 5

[0061] This embodiment discloses the application of the negative electrode current collector 100 of Example 1 or the battery described in Example 4 in a power vehicle.

[0062] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation methods of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A negative electrode current collector, characterized in that The invention comprises a support layer, wherein at least one side of the support layer is provided with a surface treatment layer, an adhesive layer and a metal layer in sequence in a direction away from the support layer; the surface treatment layer imparts surface active groups to the support layer to improve the bonding force between the support layer and the adhesive layer; The surface tension difference between the surface treatment layer and the adhesive layer ranges from 3 mN / m to 15 mN / m.

2. The negative electrode current collector according to claim 1, characterized in that The thickness of the support layer ranges from 1.9 μm to 6 μm; the thickness of the surface treatment layer ranges from 0.01 μm to 0.5 μm; the thickness of the adhesive layer ranges from 0.5 μm to 3 μm; and the thickness of the metal layer ranges from 0.8 μm to 3.5 μm.

3. The negative electrode current collector according to claim 1, wherein The surface tension difference between the surface treatment layer and the adhesive layer ranges from 3 mN / m to 10 mN / m.

4. The negative electrode current collector according to claim 1, wherein The surface tension dyne value of the surface treatment layer is ≥50; the dyne value of the metal layer is ≥46.

5. The negative electrode current collector according to claim 1, characterized in that The tensile strength of the adhesive layer is ≥250 MPa; and the elongation at break is ≥80%.

6. The negative electrode current collector according to claim 1, characterized in that The surface treatment layer is a hierarchical structure formed on the surface of the support layer by treating the support layer with a surface treatment agent, and is located between the negative electrode current collector support layer and the adhesive layer; the surface treatment agent is an adhesion promoter, specifically a polyurethane polymer material; or The surface treatment agent mainly contains 4 or more fluorine atoms and fluorinated acids of one or more elements selected from titanium, zirconium, silicon, aluminum, and boron, including fluorotitanic acid and fluorozirconic acid; or The surface treatment agent is a compound having at least one reactive functional group containing active hydrogen, namely, amino, epoxy, vinyl, and mercapto groups, including r-aminopropyltriethoxysilane and r-aminopropyltrimethoxysilane.

7. The negative electrode current collector according to claim 1, characterized in that: The adhesive layer is formed by an adhesive liquid, and the adhesive liquid is formed by a viscous liquid material whose surface tension after curing is smaller than the surface tension of the surface treatment layer and the surface tension of the metal layer.

8. The negative electrode current collector according to claim 1, characterized in that The bonding force between the adhesive layer and the metal layer ranges from 3N / 25mm to 30N / 25mm.

9. The negative electrode current collector according to claim 1, characterized in that: A cavity for accommodating functional solid fillers is reserved in the bonding layer.

10. The negative electrode current collector according to claim 1, characterized in that: The adhesive layer may be filled with functional solid fillers to further improve the performance of the insulating adhesive layer without affecting the thickness; the functional solid fillers include at least one of silicon dioxide, aluminum hydroxide, aluminum oxide, 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, multi-walled and single-walled carbon nanotubes, carbon nanofibers, polytetrafluoroethylene particles, polyurethane particles, rubber particles, polyamide particles, silicone particles, graphene, nanotube structures and antimony trioxide.

11. The negative electrode current collector according to claim 1, characterized in that: It also includes a protective layer, which is arranged on the surface of the metal layer away from the supporting layer; the protective layer is formed of at least one material selected from chromium, tungsten, molybdenum, nickel, iron, titanium, niobium, zirconium, gold, silver, platinum, carbon, chromate compounds, silane compounds and benzotriazole modified compounds.

12. The negative electrode current collector according to any one of claims 1 to 11, characterized in that: The metal layer is at least one of copper, aluminum, titanium, nickel, cadmium, iron and silver.

13. The negative electrode current collector according to any one of claims 1 to 11, 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.

14. The negative electrode current collector according to any one of claims 1 to 11, characterized in that: The surface roughness Ra of the metal layer is ≤0.3 μm; and / or the thermal shrinkage of the adhesive layer after being treated at 150° C. for 30 minutes is ≤3%; and / or the elongation of the negative electrode current collector is ≥3%.

15. A battery, characterized in that: The negative electrode current collector comprises the negative electrode current collector according to any one of claims 1 to 14.

16. A powered vehicle, characterized in that: The negative electrode current collector comprises the negative electrode current collector according to any one of claims 1 to 14 or the battery according to claim 15.

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