Current collector with U-shaped metal sheet and preparation method thereof

Abstract

The invention discloses a current collector with a U-shaped metal sheet and a preparation method of the current collector, and relates to the technical field of batteries. The current collector comprises an organic film, and U-shaped metal sheets are arranged at the two corresponding ends of the organic film; the opening end of the U-shaped metal sheet wraps the organic film to form a composite body, and metal layers are arranged on the upper surface and the lower surface of the composite body. The preparation method of the current collector comprises the following steps: step 1: (1) coating the U-shaped opening end of the U-shaped metal sheet with a conductive adhesive; (2) bonding and curing two ends of the organic film and the opening end of the U-shaped metal sheet respectively to obtain a composite metal sheet base film; and 2, plating metal layers on the upper surface and the lower surface of the composite metal sheet base film to obtain the current collector. The current collector prepared by the method has good resistivity and tensile strength.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a current collector with a U-shaped metal sheet and its preparation method. Background Technology

[0002] Current collectors have a "sandwich" structure, with an inner polymer organic film (such as PET or PP) and two metal layers (such as Cu or Al) on both sides. Due to their lightweight and structural stability, they are widely used in energy storage devices such as lithium batteries. In existing current collectors, the metal layers are usually in surface contact with the organic film. If the metal layer deposition is uneven, impurities exist on the base film surface, or the interface peels off after long-term cycling, localized current conduction problems can occur, affecting charge transfer efficiency. Current technologies often use welding to overlap metal tabs on the outer sides of the upper and lower metal layers to achieve metal layer conductivity.

[0003] However, there are still problems with the existing technology: First, during the welding process, problems such as incomplete welding and over-welding are easy to occur, resulting in poor connection stability. In addition, when the thickness of the current collector metal layer is thin, the metal layer is prone to breakage and detachment during the welding process, and the tensile strength is reduced. Second, the welding point is a local contact form, which will cause the current path to be concentrated, the contact resistance to increase, and the local temperature to rise significantly, thereby increasing the overall resistance of the current collector.

[0004] Therefore, in order to solve the above problems, it is of great significance to provide a current collector with a U-shaped metal sheet and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a current collector with a U-shaped metal sheet, so as to solve the problems raised in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A current collector with U-shaped metal sheets, the current collector comprising an organic membrane, wherein U-shaped metal sheets are disposed at corresponding ends of the organic membrane; the open ends of the U-shaped metal sheets enclose the organic membrane to form a composite, wherein metal layers are disposed on the upper and lower surfaces of the composite.

[0007] A method for preparing a current collector with a U-shaped metal sheet includes the following steps: Step 1: (1) Coat the U-shaped open end of the U-shaped metal sheet with conductive adhesive; (2) Adhere and cure the two ends of the organic film to the open end of the U-shaped metal sheet to obtain the composite metal sheet base film. Step 2: Deposit metal layers on the upper and lower surfaces of the composite metal sheet substrate to obtain the current collector.

[0008] In a more optimized manner, the conductive adhesive comprises the following components by weight: 60-70 parts metal powder, 2-5 parts silver nanowires, 10-20 parts epoxy resin, 1-3 parts modified aliphatic amine curing agent, 2.5-4.5 parts ionic liquid, 1-3 parts silver citrate, 0.5-1.5 parts ethyl cellulose, and 10-30 parts diethylene glycol butyl ether.

[0009] The metal powder includes, but is not limited to, copper powder, silver powder, and aluminum powder.

[0010] In a more optimized manner, the preparation method of the modified aliphatic amine curing agent is as follows: (1) Polyethyleneimine, triethylamine, and dimethyldichlorosilane are added sequentially to tetrahydrofuran and reacted at room temperature for 2-3 hours. The mixture is then washed and dried to obtain modified polyethyleneimine; (2) Modified polyethyleneimine, protocatechuic acid, isonicotinic acid, dicyclohexylcarbodiimide, and N-hydroxysuccinimide are added sequentially to ethanol. The temperature is set at 40-50°C, and the mixture is stirred for 6-8 hours. The mixture is then cooled and filtered to obtain the modified aliphatic amine curing agent.

[0011] In a more optimized manner, the mass ratio of polyethyleneimine, triethylamine, and dimethyldichlorosilane in the raw material of the modified polyethyleneimine is (2~3):(3~5):(2~3). The raw materials of the modified fatty amine curing agent, by weight, are: 5-10 parts modified polyethyleneimine, 1-2 parts protocatechuic acid, 0.5-1.5 parts isonicotinic acid, 4-6 parts dicyclohexylcarbodiimide, and 1-3 parts N-hydroxysuccinimide.

[0012] In a more optimized manner, the process parameters for the curing process are: curing temperature of 70~80℃ and curing time of 2~3 hours.

[0013] More preferably, the ionic liquid is composed of tetraethylene glycol dimethyl ether and lithium tetrafluoroborate in a mass ratio of (1.5~3.5):1.

[0014] In a more optimized manner, the process of depositing the metal layer is copper evaporation plating, with the following process parameters: vacuum degree of 1.0×10-4 Pa~1.0×10-5 Pa, temperature of 1650℃~1850℃, copper vapor concentration of 60mol / L~80mol / L, temperature of the first temperature zone of 45℃~55℃ and length of 5mm~10mm; temperature of the second temperature zone of 15℃~25℃ and length of 5mm~10mm, and organic film transmission speed of 20~50m / min.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are: 1. This invention designs a metal sheet into a U-shaped structure, with its open end directly connected to both ends of an organic film via conductive adhesive to form an integrated embedded electrode. This design eliminates the need for separate electrode components and high-temperature welding processes, simplifying the structure, reducing weight, and lowering costs. Furthermore, the charge concentration area formed at the bottom of the U-shape effectively improves charge flow efficiency.

[0016] 2. This invention uses a conductive adhesive to connect a U-shaped metal sheet to an organic film. The conductive adhesive uses low-cost copper powder as the main conductive filler. However, because copper powder is easily oxidized, a modified aliphatic amine curing agent is introduced. This is achieved by reacting polyethyleneimine with dimethyldichlorosilane to introduce hydrophobic silane segments, followed by grafting protocatechuic acid and isonicotinic acid to obtain the modified aliphatic amine curing agent. The catechol groups in the protocatechuic acid structure can form chelate coordination bonds in situ with the copper powder surface during mixing and curing, forming an anti-oxidation protective layer and enhancing the interfacial bonding between the copper powder and the epoxy resin matrix. The nitrogen-containing heterocycles in the isonicotinic acid structure can improve electron mobility, thereby effectively reducing the resistivity of the system. However, although the pretreated copper powder can provide a basic conductive path, its micron-sized sheet-like structure still has gaps in the resin matrix. Therefore, silver nanowires are further added, which can bridge these dispersed copper powder particles, forming electron transport paths and reducing the overall resistance of the system. Simultaneously, the added silver citrate can further reduce the system resistance.

[0017] Furthermore, this invention introduces ionic liquids into the conductive adhesive. First, ionic liquids can significantly reduce the activation energy of the curing reaction of epoxy resin, promoting efficient reaction and forming a dense and stable cross-linked network. Second, ionic liquids can generate a higher curing shrinkage rate, enabling copper powder and silver nanowires to arrange themselves more closely during the shrinkage process, reducing the contact resistance between fillers, and making the conductive pathway formed by the copper powder skeleton and silver nanowire bridges more efficient. After curing, the flexible adhesive layer formed by the conductive adhesive can buffer the stress formed between the metal and the polymer, ensuring the reliability of the connection and enhancing its tensile strength. Attached Figure Description

[0018] Figure 1 This is a structural diagram of the current collector of the present invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the following embodiments, the parts are by weight; it should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention, and they include, exemplarily, the following: polyethyleneimine (CAS: 9002-98-6, number average molecular weight 1000), triethylamine (CAS: 121-44-8), dimethyldichlorosilane (CAS: 75-78-5), protocatechuic acid (CAS: 99-50-3), isonicotinic acid (CAS: 55-22-1), and dicyclohexylcarbodiimide (CAS: 538-7). 5-0), N-hydroxysuccinimide (CAS: 6066-82-6), tetraethylene glycol dimethyl ether (CAS: 143-24-8), lithium tetrafluoroborate (CAS: 14283-07-9), silver citrate (CAS: 314040-92-1), silver nanowires (CAS: 623-53-0, diameter 30nm, length 20μm), ethyl cellulose (CAS: 9004-57-3), copper powder (particle size 5μm), PET (model: Toray F531).

[0022] Example 1: A method for preparing a current collector with a U-shaped metal sheet, the specific steps of which are as follows: I. Preparation of modified aliphatic amine curing agent: (1) 2.5 parts of polyethyleneimine, 4 parts of triethylamine, and 2.5 parts of dimethyldichlorosilane were added to 100 parts of tetrahydrofuran in sequence, reacted at room temperature for 2.5 hours, washed and dried to obtain modified polyethyleneimine; (2) 7 parts of modified polyethyleneimine, 1.5 parts of protocatechuic acid, 1 part of isonicotinic acid, 5 parts of dicyclohexylcarbodiimide, and 2 parts of N-hydroxysuccinimide were added to 50 parts of ethanol in sequence, the temperature was set at 45℃, stirred for 7 hours, cooled and filtered to obtain modified aliphatic amine curing agent.

[0023] II. Preparation of conductive adhesive: Step 1: Add 15 parts of epoxy resin to 3.5 parts of ionic liquid (composed of 2.5 parts of tetraethylene glycol dimethyl ether and 1 part of lithium tetrafluoroborate), then add 2 parts of silver citrate, 3.5 parts of silver nanowires and 1 part of ethyl cellulose in sequence, stir evenly to obtain resin slurry; Step 2: Add 65 parts of copper powder to the resin slurry obtained in Step 1, stir evenly, add 2 parts of modified fatty amine curing agent, stir evenly, let stand to defoam, and obtain conductive adhesive.

[0024] III. Preparation of current collectors: Step 1: (1) Coat the U-shaped opening end of the U-shaped metal sheet with conductive adhesive; (2) Adhere the two ends of the PET organic film to the opening end of the U-shaped metal sheet respectively, set the temperature to 75℃, and cure for 2.5 hours to obtain the composite metal sheet base film; Step 2: Evaporate copper onto the upper and lower surfaces of the composite metal substrate film. The process parameters for copper evaporation are: vacuum degree 1.0 × 10⁻⁶. -5 Pa, temperature is 1750℃, copper vapor concentration is 70mol / L, the temperature of the first temperature zone is 50℃ and the length is 7mm; the temperature of the second temperature zone is 20℃ and the length is 7mm, the organic film transmission speed is 35m / min, i.e. the metal layer; cool to room temperature to obtain the current collector.

[0025] Example 2: A method for preparing a current collector with a U-shaped metal sheet, the specific steps of which are as follows: I. Preparation of modified aliphatic amine curing agent: (1) Add 2 parts of polyethyleneimine, 3 parts of triethylamine and 2 parts of dimethyldichlorosilane to 100 parts of tetrahydrofuran in sequence, react at room temperature for 2 hours, wash and dry to obtain modified polyethyleneimine; (2) Add 5 parts of modified polyethyleneimine, 1 part of protocatechuic acid, 0.5 parts of isonicotinic acid, 4 parts of dicyclohexylcarbodiimide and 1 part of N-hydroxysuccinimide to 50 parts of ethanol in sequence, set the temperature to 40℃, stir for 6 hours, cool and filter to obtain modified aliphatic amine curing agent.

[0026] II. Preparation of conductive adhesive: Step 1: Add 10 parts of epoxy resin to 2.5 parts of ionic liquid (composed of 1.5 parts of tetraethylene glycol dimethyl ether and 1 part of lithium tetrafluoroborate), then add 1 part of silver citrate, 2 parts of silver nanowires and 0.5 parts of ethyl cellulose in sequence, stir evenly to obtain resin slurry; Step 2: Add 60 parts of copper powder to the resin slurry obtained in Step 1, stir evenly, add 1 part of modified fatty amine curing agent, stir evenly, let stand to defoam, and obtain conductive adhesive.

[0027] III. Preparation of current collectors: Step 1: (1) Coat the U-shaped open end of the U-shaped metal sheet with conductive adhesive; (2) Adhere the two ends of the PET organic film to the open end of the U-shaped metal sheet respectively, set the temperature to 70℃, and cure for 2 hours to obtain the composite metal sheet base film. Step 2: Evaporate copper onto the upper and lower surfaces of the composite metal substrate film. The process parameters for copper evaporation are: vacuum degree 1.0 × 10⁻⁶. -5 Pa, temperature is 1750℃, copper vapor concentration is 70mol / L, the temperature of the first temperature zone is 50℃ and the length is 7mm; the temperature of the second temperature zone is 20℃ and the length is 7mm, the organic film transmission speed is 35m / min, i.e. the metal layer; cool to room temperature to obtain the current collector.

[0028] Example 3: A method for preparing a current collector with a U-shaped metal sheet, the specific steps of which are as follows: I. Preparation of modified aliphatic amine curing agent: (1) Add 3 parts of polyethyleneimine, 5 parts of triethylamine and 3 parts of dimethyldichlorosilane to 100 parts of tetrahydrofuran in sequence, react at room temperature for 3 hours, wash and dry to obtain modified polyethyleneimine; (2) Add 10 parts of modified polyethyleneimine, 2 parts of protocatechuic acid, 1.5 parts of isonicotinic acid, 6 parts of dicyclohexylcarbodiimide and 3 parts of N-hydroxysuccinimide to 50 parts of ethanol in sequence, set the temperature to 50℃, stir for 8 hours, cool and filter to obtain modified aliphatic amine curing agent.

[0029] II. Preparation of conductive adhesive: Step 1: Add 20 parts of epoxy resin to 4.5 parts of ionic liquid (composed of 3.5 parts of tetraethylene glycol dimethyl ether and 1 part of lithium tetrafluoroborate), then add 3 parts of silver citrate, 5 parts of silver nanowires and 1.5 parts of ethyl cellulose in sequence, stir evenly to obtain resin slurry; Step 2: Add 70 parts of copper powder to the resin slurry obtained in Step 1, stir evenly, add 3 parts of modified fatty amine curing agent, stir evenly, let stand to defoam, and obtain conductive adhesive.

[0030] III. Preparation of current collectors: Step 1: (1) Coat the U-shaped open end of the U-shaped metal sheet with conductive adhesive; (2) Adhere the two ends of the PET organic film to the open end of the U-shaped metal sheet respectively, set the temperature to 80℃, and cure for 3 hours to obtain the composite metal sheet base film. Step 2: Evaporate copper onto the upper and lower surfaces of the composite metal substrate film. The process parameters for copper evaporation are: vacuum degree 1.0 × 10⁻⁶. -5 Pa, temperature is 1750℃, copper vapor concentration is 70mol / L, the temperature of the first temperature zone is 50℃ and the length is 7mm; the temperature of the second temperature zone is 20℃ and the length is 7mm, the organic film transmission speed is 35m / min, i.e. the metal layer; cool to room temperature to obtain the current collector.

[0031] Comparative Example 1: Based on Example 1, the modified fatty amine curing agent was prepared without the addition of isonicotinic acid, while the rest remained the same as in the example. The specific steps are as follows: I. Preparation of modified aliphatic amine curing agent: (1) 2.5 parts of polyethyleneimine, 4 parts of triethylamine, and 2.5 parts of dimethyldichlorosilane were added to 100 parts of tetrahydrofuran in sequence, reacted at room temperature for 2.5 hours, washed and dried to obtain modified polyethyleneimine; (2) 7 parts of modified polyethyleneimine, 1.5 parts of protocatechuic acid, 5 parts of dicyclohexylcarbodiimide, and 2 parts of N-hydroxysuccinimide were added to 50 parts of ethanol in sequence, the temperature was set at 45℃, stirred for 7 hours, cooled and filtered to obtain modified aliphatic amine curing agent.

[0032] II. Preparation of conductive adhesive: Step 1: Add 15 parts of epoxy resin to 3.5 parts of ionic liquid (composed of 2.5 parts of tetraethylene glycol dimethyl ether and 1 part of lithium tetrafluoroborate), then add 2 parts of silver citrate, 3.5 parts of silver nanowires and 1 part of ethyl cellulose in sequence, stir evenly to obtain resin slurry; Step 2: Add 65 parts of copper powder to the resin slurry obtained in Step 1, stir evenly, add 2 parts of modified fatty amine curing agent, stir evenly, let stand to defoam, and obtain conductive adhesive.

[0033] III. Preparation of current collectors: Step 1: (1) Coat the U-shaped opening end of the U-shaped metal sheet with conductive adhesive; (2) Adhere the two ends of the PET organic film to the opening end of the U-shaped metal sheet respectively, set the temperature to 75℃, and cure for 2.5 hours to obtain the composite metal sheet base film; Step 2: Evaporate copper onto the upper and lower surfaces of the composite metal substrate film. The process parameters for copper evaporation are: vacuum degree 1.0 × 10⁻⁶. -5 Pa, temperature is 1750℃, copper vapor concentration is 70mol / L, the temperature of the first temperature zone is 50℃ and the length is 7mm; the temperature of the second temperature zone is 20℃ and the length is 7mm, the organic film transmission speed is 35m / min, i.e. the metal layer; cool to room temperature to obtain the current collector.

[0034] Comparative Example 2: Based on Example 1, the raw materials of the modified fatty amine curing agent did not contain protocatechuic acid, but remained the same as in Example 1. The specific steps are as follows: I. Preparation of modified aliphatic amine curing agent: (1) Add 2.5 parts of polyethyleneimine, 4 parts of triethylamine, and 2.5 parts of dimethyldichlorosilane to 100 parts of tetrahydrofuran in sequence, react at room temperature for 2.5 hours, wash and dry to obtain modified polyethyleneimine; (2) Add 7 parts of modified polyethyleneimine, 1 part of isonicotinic acid, 5 parts of dicyclohexylcarbodiimide, and 2 parts of N-hydroxysuccinimide to 50 parts of ethanol in sequence, set the temperature to 45℃, stir for 7 hours, cool and filter to obtain modified aliphatic amine curing agent.

[0035] II. Preparation of conductive adhesive: Step 1: Add 15 parts of epoxy resin to 3.5 parts of ionic liquid (composed of 2.5 parts of tetraethylene glycol dimethyl ether and 1 part of lithium tetrafluoroborate), then add 2 parts of silver citrate, 3.5 parts of silver nanowires and 1 part of ethyl cellulose in sequence, stir evenly to obtain resin slurry; Step 2: Add 65 parts of copper powder to the resin slurry obtained in Step 1, stir evenly, add 2 parts of modified fatty amine curing agent, stir evenly, let stand to defoam, and obtain conductive adhesive.

[0036] III. Preparation of current collectors: Step 1: (1) Coat the U-shaped opening end of the U-shaped metal sheet with conductive adhesive; (2) Adhere the two ends of the PET organic film to the opening end of the U-shaped metal sheet respectively, set the temperature to 75℃, and cure for 2.5 hours to obtain the composite metal sheet base film; Step 2: Evaporate copper onto the upper and lower surfaces of the composite metal substrate film. The process parameters for copper evaporation are: vacuum degree 1.0 × 10⁻⁶. -5 Pa, temperature is 1750℃, copper vapor concentration is 70mol / L, the temperature of the first temperature zone is 50℃ and the length is 7mm; the temperature of the second temperature zone is 20℃ and the length is 7mm, the organic film transmission speed is 35m / min, i.e. the metal layer; cool to room temperature to obtain the current collector.

[0037] Comparative Example 3: Based on Example 1, silver nanowires were replaced with copper powder to prepare a conductive adhesive. The rest of the steps remained the same as in Example 1. The specific steps are as follows: I. Preparation of modified aliphatic amine curing agent: (1) 2.5 parts of polyethyleneimine, 4 parts of triethylamine, and 2.5 parts of dimethyldichlorosilane were added to 100 parts of tetrahydrofuran in sequence, reacted at room temperature for 2.5 hours, washed and dried to obtain modified polyethyleneimine; (2) 7 parts of modified polyethyleneimine, 1.5 parts of protocatechuic acid, 1 part of isonicotinic acid, 5 parts of dicyclohexylcarbodiimide, and 2 parts of N-hydroxysuccinimide were added to 50 parts of ethanol in sequence, the temperature was set at 45℃, stirred for 7 hours, cooled and filtered to obtain modified aliphatic amine curing agent.

[0038] II. Preparation of conductive adhesive: Step 1: Add 15 parts of epoxy resin to 3.5 parts of ionic liquid (composed of 2.5 parts of tetraethylene glycol dimethyl ether and 1 part of lithium tetrafluoroborate), then add 2 parts of silver citrate and 1 part of ethyl cellulose in sequence, stir evenly to obtain resin slurry; Step 2: Add 68.5 parts of copper powder to the resin slurry obtained in Step 1, stir evenly, add 2 parts of modified fatty amine curing agent, stir evenly, let stand to defoam, and obtain conductive adhesive.

[0039] III. Preparation of current collectors: Step 1: (1) Coat the U-shaped opening end of the U-shaped metal sheet with conductive adhesive; (2) Adhere the two ends of the PET organic film to the opening end of the U-shaped metal sheet respectively, set the temperature to 75℃, and cure for 2.5 hours to obtain the composite metal sheet base film; Step 2: Evaporate copper onto the upper and lower surfaces of the composite metal substrate film. The process parameters for copper evaporation are: vacuum degree 1.0 × 10⁻⁶. -5 Pa, temperature is 1750℃, copper vapor concentration is 70mol / L, the temperature of the first temperature zone is 50℃ and the length is 7mm; the temperature of the second temperature zone is 20℃ and the length is 7mm, the organic film transmission speed is 35m / min, i.e. the metal layer; cool to room temperature to obtain the current collector.

[0040] Comparative Example 4: Based on Example 1, the component ratio in the ionic liquid was adjusted by adding 1.5 parts tetraethylene glycol dimethyl ether and 2 parts lithium tetrafluoroborate to prepare a conductive adhesive. Other steps remained the same as in Example 1. The specific steps are as follows: I. Preparation of modified aliphatic amine curing agent: (1) 2.5 parts of polyethyleneimine, 4 parts of triethylamine, and 2.5 parts of dimethyldichlorosilane were added to 100 parts of tetrahydrofuran in sequence, reacted at room temperature for 2.5 hours, washed and dried to obtain modified polyethyleneimine; (2) 7 parts of modified polyethyleneimine, 1.5 parts of protocatechuic acid, 1 part of isonicotinic acid, 5 parts of dicyclohexylcarbodiimide, and 2 parts of N-hydroxysuccinimide were added to 50 parts of ethanol in sequence, the temperature was set at 45℃, stirred for 7 hours, cooled and filtered to obtain modified aliphatic amine curing agent.

[0041] II. Preparation of conductive adhesive: Step 1: Add 15 parts of epoxy resin to 3.5 parts of ionic liquid (composed of 1.5 parts of tetraethylene glycol dimethyl ether and 2 parts of lithium tetrafluoroborate), then add 2 parts of silver citrate, 3.5 parts of silver nanowires and 1 part of ethyl cellulose in sequence, stir evenly to obtain resin slurry; Step 2: Add 65 parts of copper powder to the resin slurry obtained in Step 1, stir evenly, add 2 parts of modified fatty amine curing agent, stir evenly, let stand to defoam, and obtain conductive adhesive.

[0042] III. Preparation of current collectors: Step 1: (1) Coat the U-shaped opening end of the U-shaped metal sheet with conductive adhesive; (2) Adhere the two ends of the PET organic film to the opening end of the U-shaped metal sheet respectively, set the temperature to 75℃, and cure for 2.5 hours to obtain the composite metal sheet base film; Step 2: Evaporate copper onto the upper and lower surfaces of the composite metal substrate film. The process parameters for copper evaporation are: vacuum degree 1.0 × 10⁻⁶. -5Pa, temperature is 1750℃, copper vapor concentration is 70mol / L, the temperature of the first temperature zone is 50℃ and the length is 7mm; the temperature of the second temperature zone is 20℃ and the length is 7mm, the organic film transmission speed is 35m / min, i.e. the metal layer; cool to room temperature to obtain the current collector.

[0043] Performance testing: (1) Conductivity testing: The conductive adhesives prepared in Examples 1-3 and Comparative Examples 1-4 were tested for conductivity. The conductive adhesives were coated on release paper and cured at 75°C for 2.5 hours to form a solid adhesive film. The volume conductivity was tested using a four-probe resistivity tester; (2) Tensile strength test: The composite metal sheet films prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to tensile strength test using a universal tensile testing machine; the test data are shown in the table below:

[0044] According to the data in the table, the conductive adhesives prepared in Examples 1-3 have good volume resistivity and tensile strength. Comparative Example 1 lacks isonicotinic acid and uses only protocatechuic acid, which lacks nitrogen-containing heterocycles to promote electron migration, thus increasing the volume resistivity. Comparative Example 2 lacks protocatechuic acid and lacks the chelating function of catechol groups, thus completely lacking the protection of copper powder. Copper powder oxidizes rapidly and severely during mixing and curing, resulting in a significant increase in its volume resistivity. In Comparative Example 3, the absence of silver nanowires led to a lack of conductive pathways in the dispersed copper powder, thus increasing volume resistivity. In Comparative Example 4, the imbalanced ratio of ionic liquid components increased system viscosity, interfering with the strengthening effect of curing shrinkage on conductive pathways, leading to increased volume resistivity. Tensile strength data shows that Examples 1-3 exhibit good tensile strength. The strong interfacial bonding and dense cross-linked network formed by the curing agent, along with the fiber reinforcement effect of the silver nanowires, ensured good tensile strength of the adhesive layer. Comparative Example 1 lacked isonicotinic acid, resulting in a lack of rigid segments and insufficient rigidity of the cross-linked network, thus reducing tensile strength. Comparative Example 2 lacked the strong interfacial interaction provided by catechol-copper, reducing the interfacial bonding force between copper powder and the epoxy resin matrix, thus significantly decreasing tensile strength. Comparative Example 3 lacked the fiber reinforcement effect of silver nanowires, weakening the mechanical properties of the colloid and reducing tensile strength. In Comparative Example 4, the imbalanced ratio of ionic liquid hindered normal curing of the epoxy resin, leading to a loose cross-linked network and a significant decrease in tensile strength. In summary, the synergistic effect of modified aliphatic amine curing agents, ionic liquids, copper powder, and silver nanowires can impart good volume resistivity and tensile strength to conductive adhesives.

[0045] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included within the present invention.

Claims

1. A current collector with a U-shaped metal sheet, characterized in that: The current collector includes an organic membrane, and U-shaped metal sheets are provided at both ends of the organic membrane; the open ends of the U-shaped metal sheets enclose the organic membrane to form a composite, and metal layers are provided on the upper and lower surfaces of the composite.

2. The method for preparing a current collector with a U-shaped metal sheet according to claim 1, characterized in that: Includes the following steps: Step 1: (1) Coat the U-shaped open end of the U-shaped metal sheet with conductive adhesive; (2) Adhere and cure the two ends of the organic film to the open end of the U-shaped metal sheet to obtain the composite metal sheet base film. Step 2: Deposit metal layers on the upper and lower surfaces of the composite metal sheet substrate to obtain the current collector.

3. The method for preparing a current collector with a U-shaped metal sheet according to claim 2, characterized in that: The conductive adhesive comprises the following components by weight: 60-70 parts metal powder, 2-5 parts silver nanowires, 10-20 parts epoxy resin, 1-3 parts modified aliphatic amine curing agent, 2.5-4.5 parts ionic liquid, 1-3 parts silver citrate, 0.5-1.5 parts ethyl cellulose, and 10-30 parts diethylene glycol butyl ether.

4. The method for preparing a current collector with a U-shaped metal sheet according to claim 3, characterized in that: The modified fatty amine curing agent is prepared as follows: (1) Polyethyleneimine, triethylamine, and dimethyldichlorosilane are added sequentially to tetrahydrofuran and reacted at room temperature for 2-3 hours. The mixture is then washed and dried to obtain modified polyethyleneimine; (2) Modified polyethyleneimine, protocatechuic acid, isonicotinic acid, dicyclohexylcarbodiimide, and N-hydroxysuccinimide are added sequentially to ethanol. The temperature is set at 40-50℃, and the mixture is stirred for 6-8 hours. The mixture is then cooled and filtered to obtain the modified fatty amine curing agent.

5. The method for preparing a current collector with a U-shaped metal sheet according to claim 4, characterized in that: In the raw material of the modified polyethyleneimine, the mass ratio of polyethyleneimine, triethylamine, and dimethyldichlorosilane is (2~3):(3~5):(2~3). The raw materials of the modified fatty amine curing agent, by weight, are: 5-10 parts modified polyethyleneimine, 1-2 parts protocatechuic acid, 0.5-1.5 parts isonicotinic acid, 4-6 parts dicyclohexylcarbodiimide, and 1-3 parts N-hydroxysuccinimide.

6. The method for preparing a current collector with a U-shaped metal sheet according to claim 2, characterized in that: The process parameters for the curing process are: curing temperature 70~80℃, curing time 2~3 hours.

7. The method for preparing a current collector with a U-shaped metal sheet according to claim 3, characterized in that: The ionic liquid is composed of tetraethylene glycol dimethyl ether and lithium tetrafluoroborate in a mass ratio of (1.5~3.5):

1.

8. The method for preparing a current collector with a U-shaped metal sheet according to claim 2, characterized in that: The process for plating the metal layer is copper evaporation plating, with the following process parameters: vacuum degree 1.0 × 10⁻⁶. -4 Pa ~ 1.0 × 10 -5 Pa, temperature is 1650℃~1850℃, copper vapor concentration is 60mol / L~80mol / L, temperature of the first temperature zone is 45℃~55℃, length is 5mm~10mm; temperature of the second temperature zone is 15℃~25℃, length is 5mm~10mm, organic membrane transmission speed is 20~50m / min.

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