Composite current collector, preparation method therefor, and secondary battery

Abstract

The present application belongs to the technical field of battery materials, and provides a composite current collector, a preparation method therefor, and a secondary battery. The preparation method comprises the following steps: (1) unwinding a magnetron sputtering film and performing pretreatment; (2) plating a nickel-phosphorus alloy layer on at least one side surface of the magnetron sputtering film using a chemical nickel-phosphorus plating process; (3) performing pore-sealing treatment on the composite film obtained in step (2) using a silane pore-sealing process, the specific steps of the silane pore-sealing process comprising: performing pore-sealing treatment on the obtained composite film with a pore-sealing solution; and (4) performing double-sided copper plating on the pore-sealed composite film, followed by post-treatment to obtain the composite current collector. In the present application, the chemical nickel-phosphorus plating process and silane pore-sealing process are introduced before copper plating of the magnetron sputtering film, increasing the film surface density and adhesion, improving the yield, reducing the requirements for the thickness and sheet resistance of the magnetron sputtering film, and simultaneously lowering the probability of perforation of the magnetron sputtering film.

Description

Composite current collector, preparation method thereof and secondary battery TECHNICAL FIELD

[0001] The present application belongs to the technical field of battery materials, and particularly relates to a composite current collector, a preparation method thereof and a secondary battery. BACKGROUND

[0002] At present, the double-sided copper plating processing technology for the surfaces of various types of plastic ultra-thin films (such as PP films or PET films, but not limited to these two types) is to perform double-sided water acid copper plating film processing on the magnetron films (which have been subjected to double-sided magnetron copper plating processing). This process requires a high magnetron film, and the sheet resistance of the double-sided acid copper film before processing needs to be at least 1Ω or less, and the thickness needs to reach 40-60nm. The energy required in the magnetron plating film process is high, and it is very easy to perforate or peel off the copper, thereby causing a large number of unqualified products due to poor compactness, and a low qualified rate of physical properties such as adhesion.

[0003] Therefore, it is urgent to provide a method which can not only solve the problems of poor compactness and adhesion of the product film produced by the magnetron copper plating process, but also significantly reduce the requirements for the thickness and sheet resistance of the magnetron film, thereby improving the qualified rate of the product. SUMMARY

[0004] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of protection of the claims.

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a composite current collector, a preparation method thereof and a secondary battery. The present application introduces a chemical nickel-phosphorus plating process and a silane hole sealing process before plating copper on the magnetron film. On the one hand, the compactness and adhesion of the film surface are increased, the qualified rate of the composite current collector is improved, and on the other hand, the requirements for the thickness and sheet resistance of the magnetron film are reduced, the sheet resistance is below 2Ω, and the thickness is 20-40nm, thereby reducing the total energy and process difficulty of the magnetron film production process, and simultaneously reducing the probability of perforation of the magnetron film.

[0006] To achieve this purpose, the following technical solutions are adopted in the present application:

[0007] In a first aspect, the present application provides a preparation method of a composite current collector, which comprises the following steps:

[0008] (1) unwinding the magnetron film and performing pretreatment;

[0009] (2) using a chemical nickel-phosphorus plating process to plate a nickel-phosphorus alloy layer on both sides of the surface of the magnetron film;

[0010] (3) performing a sealing treatment on the composite film obtained in step (2) by using a silane sealing process; the specific steps of the silane sealing process include: performing a sealing treatment on the obtained composite film by using a sealing solution;

[0011] (4) performing double-sided copper plating on the composite film after the sealing treatment, and then performing a post-treatment, to obtain the composite current collector.

[0012] The present application introduces a chemical nickel-phosphorus plating process and a silane sealing process before performing copper plating on the magnetron film, which on one hand increases the compactness and adhesion of the film surface, improves the qualified rate of the composite current collector, and on the other hand reduces the requirements for the thickness and square resistance of the magnetron film layer, the square resistance is below 2Ω, and the thickness is 20-40 nm, thereby reducing the total energy and process difficulty of the magnetron film production process, and simultaneously reducing the probability of the magnetron film out of the hole.

[0013] As an optional technical solution of the present application, the pre-treatment step of step (1) includes water washing.

[0014] In an embodiment, the magnetron film of step (1) includes a base film, and a copper layer arranged on the two side surfaces of the base film.

[0015] In an embodiment, the material of the base film includes PP (polypropylene) and / or PET (polyethylene terephthalate).

[0016] In an embodiment, the square resistance of the two surfaces of the magnetron film of step (1) is 1-2Ω, for example, which can be 1Ω, 1.5Ω or 2Ω, etc.

[0017] In an embodiment, the thickness of the copper layer on a single surface is 20-40 nm, for example, which can be 20 nm, 30 nm or 40 nm, etc.

[0018] As an optional technical solution of the present application, the chemical nickel-phosphorus plating process of step (2) is a low-phosphorus weak-alkaline chemical nickel process, and the specific steps of the low-phosphorus weak-alkaline chemical nickel process include:

[0019] (a) mixing a nickel plating solution, a complexing compound, an accelerator, a stabilizer, a wetting agent and a phosphorus plating solution to obtain a chemical plating solution;

[0020] (b) placing the magnetron film in the chemical plating solution to perform a plating reaction, to obtain a nickel-phosphorus alloy layer.

[0021] In the present application, the low-phosphorus weak-alkaline chemical nickel process is used to plate the nickel-phosphorus alloy layer, if the copper layer on the previous magnetron film has poor plating property and the plated layer is thin, the coverage can also be formed, which avoids the corrosion of the magnetron copper layer in the acid environment, and the weak-alkaline environment also avoids the pressure of the subsequent water washing step, and avoids the pollution of the nickel plating solution to the sealing solution and the subsequent acid copper solution.

[0022] As an optional technical solution of the present application, the plating nickel solution in step (a) comprises a nickel salt, and the nickel salt comprises any one or a combination of at least two of nickel chloride, nickel sulfate or nickel acetate.

[0023] In an embodiment, the concentration of the plating nickel solution in step (a) is 20-40 g / L, for example, it can be 20 g / L, 25 g / L, 30 g / L, 35 g / L or 40 g / L, etc.

[0024] In an embodiment, the plating nickel solution in step (a) is prepared by dissolving a nickel salt in water and heating, and the heating temperature is 60-80℃, for example, it can be 60℃, 65℃, 70℃, 75℃ or 80℃, etc.

[0025] It should be noted that the plating nickel solution is configured by an independent tank, and 1 / 3 of the water volume of the tank is used to heat and dissolve the nickel salt.

[0026] In an embodiment, the plating phosphorus solution in step (a) comprises a phosphorus salt, and the phosphorus salt comprises sodium hypophosphite monohydrate and / or sodium dihydrogen phosphate.

[0027] It should be noted that sodium hypophosphite monohydrate is also used as a reducing agent, and when used as a reducing agent, the metal ions in the plating solution can be reduced to metal and deposited on the surface of the plated part.

[0028] In an embodiment, the concentration of the plating phosphorus solution in step (a) is 10-40 g / L, for example, it can be 10 g / L, 20 g / L, 30 g / L or 40 g / L, etc.

[0029] In an embodiment, the mass ratio of nickel ions in the plating nickel solution to phosphate ions in the plating phosphorus solution in step (a) is (0.3-0.6):1, for example, it can be 0.3:1, 0.4:1, 0.5:1 or 0.6:1, etc., and further optionally (0.3-0.4):1.

[0030] In the present application, when the mass ratio of nickel ions in the plating nickel solution to phosphate ions in the plating phosphorus solution is too small or too large, i.e. less than 0.3 or greater than 0.6, the plating film rate of the nickel-phosphorus alloy layer is low, and the plated layer is dark.

[0031] It should be noted that the preparation of the plating phosphorus solution is prepared in an independent tank, i.e. 1 / 3 of the water volume of the main tank is used to dissolve the phosphorus salt.

[0032] As an optional technical solution of the present application, the specific steps of step (a) include:

[0033] The complexing compound, the accelerator, the stabilizer and the wetting agent are mixed once to obtain a first mixed solution, and then the first mixed solution and the nickel plating solution are mixed twice to obtain a second mixed solution, and then the second mixed solution and the phosphorus plating solution are mixed three times.

[0034] It should be noted that the first mixed solution is obtained by dissolving water in the main tank in an amount of 1 / 3 of the total volume of the tank.

[0035] In an embodiment, the complexing compound includes any one or a combination of at least two of ammonium salt, citrate salt or potassium pyrophosphate, and is further optionally a combination of ammonium salt, citrate salt and potassium pyrophosphate.

[0036] In an embodiment, the mass ratio of the ammonium salt, the citrate salt and the potassium pyrophosphate in the first mixed solution is (20-50):(20-50):(30-50), wherein the selection range "20-50" of the ammonium salt exemplarily includes 20, 30, 40 or 50, the selection range "20-50" of the citrate salt exemplarily includes 20, 30, 40 or 50, and the selection range "30-50" of the potassium pyrophosphate exemplarily includes 30, 40 or 50.

[0037] In an embodiment, the complexing compound further includes a lactic acid solution.

[0038] It should be noted that the mass fraction of the lactic acid solution is not specifically limited in the present application, and exemplarily can be 80% or the like.

[0039] In an embodiment, the ammonium salt includes ammonium chloride and / or ammonium sulfate.

[0040] In an embodiment, the citrate salt includes sodium citrate and / or ammonium citrate.

[0041] In an embodiment, the accelerator includes any one or a combination of at least two of ammonia, fatty acid, propionic acid, succinic acid, malic acid, triethanolamine, fluoride or lithium salt, and is further optionally ammonia.

[0042] In an embodiment, the mass concentration of the accelerator in the first mixed solution is 10-30 g / L, and can be 10 g / L, 15 g / L, 20 g / L, 25 g / L or 30 g / L or the like.

[0043] In one embodiment, the stabilizer includes any one of thiourea, 3-5 isothiuronium propyl sulfonate, phthalic anhydride, hexamethylene tetra phthalic anhydride, mercaptobenzothiazole, xanthate or sodium thiosulfate or a combination of at least two of them, and further optionally a combination of thiourea, 3-5 isothiuronium propyl sulfonate, hexamethylene tetra phthalic anhydride and sodium thiosulfate.

[0044] In one embodiment, the mass ratio of thiourea, 3-5 isothiuronium propyl sulfonate, hexamethylene tetra phthalic anhydride and sodium thiosulfate in the primary mixed solution is (0.0008-0.001):(10-20):(1-2):(0.001-0.002), wherein the selected range of "0.0008-0.001" of thiourea can be 0.0008, 0.0009 or 0.001, etc., the selected range of "10-20" of 3-5 isothiuronium propyl sulfonate can be 10, 12, 14, 16, 18 or 20, etc., the selected range of "1-2" of hexamethylene tetra phthalic anhydride can be 1, 1.2, 1.4, 1.6, 1.8 or 2, etc., and the selected range of "0.001-0.002" of sodium thiosulfate can be 0.001, 0.0012, 0.0014, 0.0016, 0.0018 or 0.002, etc.

[0045] In the present application, the wetting agent is a surfactant suitable for the plating film environment. For example, it can be sodium dodecyl benzene sulfonate or sodium dodecyl sulfate, etc.

[0046] In one embodiment, the mass concentration of the wetting agent in the primary mixed solution is 50-100 g / L, for example, it can be 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L or 100 g / L, etc.

[0047] In one embodiment, a brightener is also added in the process of primary mixing, and the brightener includes copper sulfate and / or potassium iodate.

[0048] In the present application, the nickel-phosphorus alloy layer is an intermediate plating layer, and the brightness requirement is not high. In order to achieve the purpose of avoiding pollution as much as possible, copper sulfate and / or potassium iodate are used as brighteners. In addition, thiourea and sodium thiosulfate in the stabilizer can also produce a brightening effect of the plating layer simultaneously.

[0049] In one embodiment, when the brightener is copper sulfate, the mass concentration of the brightener in the primary mixed solution is 10-20 mg / L, for example, it can be 10 mg / L, 12 mg / L, 14 mg / L, 16 mg / L, 18 mg / L or 20 mg / L, etc.

[0050] In one embodiment, when the brightener is potassium iodate, the mass concentration of the brightener in the primary mixture is 2-6 mg / L, for example, it can be 2 mg / L, 3 mg / L, 4 mg / L, 5 mg / L or 6 mg / L, etc.

[0051] In one embodiment, a pH buffer is also added during the primary mixing process.

[0052] In one embodiment, the pH buffer comprises any one or a combination of at least two of boric acid, glycolic acid, acetic acid, oxalic acid, succinic acid, ammonia, sodium hydroxide, potassium hydroxide, or sodium bicarbonate, and may further be selected as boric acid or ammonia.

[0053] In this application, if it is necessary to adjust the pH value to a lower level, boric acid, glycolic acid, acetic acid, oxalic acid, or succinic acid can be used. More specifically, boric acid at a concentration of 10-20 g / L (e.g., 10 g / L, 15 g / L, or 20 g / L) can be used. This concentration is the concentration of boric acid added to the primary mixture as a buffer. If it is necessary to adjust the pH value to a higher level, ammonia, sodium hydroxide, potassium hydroxide, or sodium bicarbonate can be used. Considering the overall cost, ammonia is preferred.

[0054] It should be noted that this application does not limit the mass fraction of ammonia water. For example, it can be 25-28%, such as 25%, 26%, 27% or 28%.

[0055] In one embodiment, the pH value of the primary mixture is 7.5-10, for example, it can be 7.5, 8, 8.5, 9, 9.5 or 10, and more preferably 8-9.5.

[0056] As an optional technical solution of this application, the volume ratio of the nickel plating solution, the primary mixed solution, and the phosphorus plating solution is (0.8-1.2):(0.8-1.2):(0.8-1.2). The range of the nickel plating solution "0.8-1.2" can be, for example, 0.8, 0.9, 1, 1.1, or 1.2. The range of the primary mixed solution "0.8-1.2" can be, for example, 0.8, 0.9, 1, 1.1, or 1.2. The range of the phosphorus plating solution "0.8-1.2" can be, for example, 0.8, 0.9, 1, 1.1, or 1.2.

[0057] In one embodiment, the pH value of the electroless plating solution in step (a) is 8-9.5, for example, it can be 8, 8.5, 9 or 9.5, etc.

[0058] In this application, if the pH value of the chemical plating solution is too low, the reaction rate is slow and the deposition rate is low; if the pH value of the chemical plating solution is too high, the reaction is violent, the plating solution boils, the coating is rough, and dark gray nickel powder appears in the plating solution.

[0059] As an optional technical solution of the present application, the plating reaction in step (b) is accompanied by ultrasonic, and the frequency of the ultrasonic is 20-40 KHz, for example, it can be 20 KHz, 25 KHz, 30 KHz, 35 KHz or 40 KHz, and further optionally 25-30 KHz.

[0060] In the present application, the ultrasonic is used to assist, which has the following effects: 1) reducing the plating solution temperature, which can start plating at a minimum of 30℃; 2) improving the deposition rate of the plating layer; 3) improving the quality of the plating layer.

[0061] It should be noted that, in order to prevent the decomposition of the electroless plating solution under the action of ultrasonic, limiting the frequency of the ultrasonic to 20-40 KHz can alleviate the instability of the electroless plating solution.

[0062] In an embodiment, the temperature of the plating reaction in step (b) is 30-65℃, for example, it can be 30℃, 40℃, 50℃, 60℃ or 65℃, and further optionally 40-55℃.

[0063] In the present application, if the temperature of the plating reaction is too low, the reaction speed is slow and the deposition rate is low; if the temperature of the plating reaction is too high, the reaction is violent, the plating solution is boiling, the plating layer is rough, and dark gray nickel powder appears in the plating solution.

[0064] In an embodiment, the drawing film line speed during the plating reaction in step (b) is 3-6 m / min, for example, it can be 3 m / min, 4 m / min, 5 m / min or 6 m / min.

[0065] In the present application, the electroless nickel-phosphorus process lengthens the drawing film distance of subsequent copper plating, so the line speed should not be too fast after introducing this process, and it is optimal to maintain at 3-6 m / min. If the drawing film line speed is too slow, the overall efficiency is reduced and the production capacity is small; if the drawing film line speed is too fast, the film formation is not timely, resulting in that the thickness of the electroless plating layer does not meet the process requirements.

[0066] In an embodiment, the time of the plating reaction in step (b) is 0.5-3 min, for example, it can be 0.5 min, 1 min, 1.5 min, 2 min, 2.5 min or 3 min.

[0067] In the present application, if the time of the plating reaction is too long, the overall efficiency is reduced and the production capacity is small; if the time of the plating reaction is too short, the film formation is not timely, resulting in that the thickness of the electroless plating layer does not meet the process requirements.

[0068] In an embodiment, the preparation step of the pore sealing solution comprises mixing silane coupling agent, ethanol and water, and performing hydrolysis treatment.

[0069] In an embodiment, the silane coupling agent comprises glycidoxypropyltrimethoxysilane.

[0070] In an embodiment, the volume ratio of the silane coupling agent, ethanol and water is (40-50):(40-45):(5-20), wherein the selected range "40-50" of the silane coupling agent may be 40, 42, 44, 46, 48 or 50, etc., the selected range "40-45" of the ethanol may be 40, 41, 42, 43, 44 or 45, etc., and the selected range "5-20" of the water may be 5, 10, 15 or 20, etc.

[0071] In an embodiment, the temperature of the hydrolysis treatment is room temperature, and the time of the hydrolysis treatment is 70-80h, for example, 70h, 72h, 75h, 78h or 80h, etc.

[0072] It should be noted that the specific temperature of the room temperature is not limited in the present application, and for example, it may be 25±5℃, such as 20℃, 25℃ or 30℃, etc.

[0073] In an embodiment, the time of the hole sealing treatment is 1-3min, for example, 1min, 1.5min, 2min, 2.5min or 3min, etc.

[0074] As an optional technical solution of the present application, the double-sided copper plating method of step (4) comprises a double-sided electroplating acid copper method.

[0075] In an embodiment, the post-treatment of step (4) comprises the following steps in sequence: water washing, anti-oxidation process, drying and winding process.

[0076] As an optional technical solution of the present application, the preparation method comprises the following steps:

[0077] (1) unwinding the magnetron film, and then water washing;

[0078] wherein the magnetron film is a base film coated with a copper layer with a thickness of 20-40nm on both sides;

[0079] (2) using a low-phosphorus weak alkaline chemical nickel process to plate a nickel-phosphorus alloy layer on both sides of the magnetron film, and the specific steps comprise:

[0080] (a) heating and dissolving a nickel salt in water at 60-80℃ to obtain a nickel salt solution with a concentration of 20-40g / L; preparing a phosphorus salt solution with a concentration of 10-40g / L; the mass ratio of nickel ions in the nickel salt solution to phosphate ions in the phosphorus salt solution is (0.3-0.6):1;

[0081] The complexing compound, the accelerator, the stabilizer, the wetting agent, the brightener and the pH buffer are mixed once to obtain a first mixed solution with a pH value of 7.5-10, then the first mixed solution and the nickel salt solution are mixed twice to obtain a second mixed solution, and then the second mixed solution and the phosphorus salt solution are mixed three times to obtain a chemical plating solution with a pH value of 8-9.5;

[0082] In the first mixed solution, the complexing compound includes lactic acid solution, ammonium salt, citrate and potassium pyrophosphate with a mass ratio of (5-20):(20-50):(20-50):(30-50); the accelerator is ammonia water, and the mass concentration of ammonia water in the first mixed solution is 10-30 g / L; in the first mixed solution, the stabilizer includes thiourea, 3-5 isothiuronium salt propane sulfonate, hexamethylene tetraanhydride and sodium thiosulfate with a mass ratio of (0.0008-0.001):(10-20):(1-2):(0.001-0.002); the mass concentration of the wetting agent in the first mixed solution is 50-100 g / L; the brightener in the first mixed solution is copper sulfate with a mass concentration of 10-20 mg / L or potassium iodate with a mass concentration of 2-6 mg / L; the pH buffer is boric acid or ammonia water; the volume ratio of the nickel salt solution, the first mixed solution and the phosphorus salt solution is (0.8-1.2):(0.8-1.2):(0.8-1.2);

[0083] (b) placing the magnetic control film in the chemical plating solution and performing a plating reaction at 30-65℃ for 0.5-3 min to obtain a nickel-phosphorus alloy layer;

[0084] In the process of the plating reaction, ultrasonic is accompanied, and the frequency of the ultrasonic is 20-40 KHz; in the process of the plating reaction, the film drawing line speed is 3-6 m / min;

[0085] (3) performing a hole sealing treatment on the composite film obtained in step (2) by using a silane hole sealing process, and the specific steps include:

[0086] (c) mixing silane coupling agent, ethanol and water at room temperature according to a volume ratio of (40-50):(40-45):(5-20) and performing a hydrolysis treatment under stirring for 70-80 h to obtain a hole sealing solution;

[0087] (d) soaking the composite film obtained in step (2) in the hole sealing solution and performing a hole sealing treatment for 1-3 min;

[0088] (4) after the hole sealing treatment, washing the composite film, performing a double-side electroplating acid copper process, then sequentially performing a double reverse flow washing process, an anti-oxidation process, drying and a winding process, and the winding process includes slitting to obtain the composite current collector.

[0089] It should be noted that double reverse flow water washing refers to water washing with two water washing tanks, the second water washing tank flows fresh water to the first water washing tank, and the first water washing tank (i.e. the first water washing tank for washing the membrane) discharges dirty water.

[0090] In a second aspect, the application provides a composite current collector prepared by the preparation method of the first aspect, wherein the composite current collector has an elongation of ≥ 9% in the MD direction, for example, 9%, 10%, 11% or 12%, and an elongation of ≥ 5% in the TD direction, for example, 5%, 9%, 10%, 11% or 12%.

[0091] It should be noted that the MD direction refers to the direction of drawing the film, i.e. along the machine direction, and the TD direction refers to the width direction.

[0092] In one embodiment, the composite current collector has a square resistance of ≤ 2Ω, for example, 2Ω, 1.5Ω, 1Ω or 0.5Ω.

[0093] In a third aspect, the application provides a secondary battery comprising the composite current collector prepared by the preparation method of the first aspect, or comprising the composite current collector of the second aspect.

[0094] The numerical ranges described herein include all the point values within the range, and also include any and all ranges between the listed point values. For the sake of brevity, the specification can not list every individual value within a range, but it should be understood that if any lower numerical limit or upper numerical limit is used in the detailed description, examples, or claims, the application also contemplates ranges using either the lower and / or upper numerical limits. Unless otherwise stated, all ranges include any and all sub-ranges thereof, and are inclusive of the minimum and maximum values of the range.

[0095] Compared with the prior art, the application has the following beneficial effects:

[0096] The application introduces a chemical nickel-phosphorus plating process and a silane hole sealing process before copper plating of the magnetron film, which on the one hand increases the compactness and adhesion of the film surface, improves the qualified rate of the composite current collector, and on the other hand reduces the requirements for the thickness and square resistance of the magnetron film layer, the square resistance is below 2Ω, and the thickness is 20-40 nm, thereby reducing the total energy and process difficulty of the magnetron film production process, and simultaneously reducing the probability of magnetron film hole.

[0097] Other aspects can become apparent from the following detailed description, when read in conjunction with the drawings. DETAILED DESCRIPTION

[0098] The technical solutions of the application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the application, and should not be regarded as specific limitations on the application.

[0099] Example 1

[0100] The embodiment provides a preparation method of a composite current collector, and the preparation method comprises the following steps:

[0101] (1) unwinding the magnetron film, and then performing water washing;

[0102] In the embodiment, the magnetron film is a base film coated with a copper layer with a thickness of 40 nm on both sides, the base film is a PP film, and the sheet resistance of the magnetron film is 1.5 Ω;

[0103] (2) adopting a low-phosphorus weak-alkaline chemical nickel process to plate a nickel-phosphorus alloy layer on at least one side surface of the magnetron film, and the specific steps comprise the following steps:

[0104] (a) heating and dissolving a nickel salt (nickel chloride) with 1 / 3 water volume of a total volume of a tank to obtain a nickel salt solution with a concentration of 30 g / L, the heating temperature is 70 ℃; dissolving a phosphorus salt (sodium hypophosphite monohydrate) with 1 / 3 water volume of the total volume of the tank to obtain a phosphorus salt solution with a concentration of 25 g / L; the mass ratio of nickel ions in the nickel salt solution to phosphate ions in the phosphorus salt solution is 0.45:1;

[0105] mixing a complex compound, an accelerator, a stabilizer, a wetting agent, a brightener and a pH buffer in the main tank with 1 / 3 water volume of the total volume of the tank to obtain a first mixed solution with a pH value of 8.5, then adding the first mixed solution into the nickel salt solution to perform secondary mixing under stirring to obtain a second mixed solution, then performing third mixing of the second mixed solution and the filtered phosphorus salt solution, and diluting to the total volume of the main tank to obtain a chemical plating solution with a pH value of 8;

[0106] In the first mixed solution, the complex compound comprises lactic acid solution (80% in mass fraction), ammonium sulfate, ammonium citrate and potassium pyrophosphate with a mass ratio of 5:35:35:40; the accelerator is ammonia water, and the mass concentration of the ammonia water in the first mixed solution is 20 g / L; in the first mixed solution, the stabilizer comprises thiourea, 3-5 isothiuronium propyl sulfonate, hexamethylene tetraanhydride and sodium thiosulfate with a mass ratio of 0.0009:15:1.5:0.0015; the mass concentration of the wetting agent in the first mixed solution is 75 g / L, and the wetting agent is sodium dodecyl benzene sulfonate; in the first mixed solution, the brightener is copper sulfate with a mass concentration of 15 mg / L; the pH buffer is boric acid; and the volume ratio of the nickel salt solution, the first mixed solution and the phosphorus salt solution is 1:1:1;

[0107] (b) placing the magnetron film in the chemical plating solution, starting an ultrasonic device, and performing plating reaction at 45 ℃ for 1.5 min to obtain a nickel-phosphorus alloy layer;

[0108] The frequency of the ultrasonic device is 30 KHz, and the film drawing speed is 4.5 m / min during the plating reaction.

[0109] (3) performing a hole sealing treatment on the composite film obtained in step (2) by using a silane hole sealing process, the specific steps comprising:

[0110] (c) mixing silane coupling agent (glycidoxypropyltrimethoxysilane), ethanol and water at room temperature (i.e. 25℃) according to a volume ratio of 45:45:10, and performing a hydrolysis treatment for 72 hours under stirring to obtain a hole sealing solution;

[0111] (d) immersing the composite film obtained in step (2) in the hole sealing solution to perform a hole sealing treatment for 2 minutes;

[0112] (4) after the hole sealing treatment, performing a double-side acid copper plating process on the composite film, and then sequentially performing a double reverse flow water washing process, an anti-oxidation process, drying and a winding process, wherein the winding process comprises slitting to obtain the composite current collector.

[0113] Example 2

[0114] The present embodiment provides a preparation method of a composite current collector, which comprises the following deficiencies:

[0115] (1) unwinding the magnetron film, and then performing water washing;

[0116] The magnetron film is a base film coated with a copper layer with a thickness of 40 nm on both sides, the base film is a PP film, and the square resistance of the magnetron film is 1.5 Ω.

[0117] (2) performing a nickel-phosphorus alloy plating on both sides of the magnetron film by using a low-phosphorus weak alkaline chemical nickel process, the specific steps comprising:

[0118] (a) dissolving a nickel salt (nickel chloride) with 1 / 3 water volume of the total volume of the tank to obtain a nickel salt solution with a concentration of 20 g / L at a heating temperature of 60℃; dissolving a phosphorus salt (sodium hypophosphite monohydrate) with 1 / 3 water volume of the main tank to obtain a phosphorus salt solution with a concentration of 10 g / L; the mass ratio of nickel ions in the nickel salt solution to phosphate ions in the phosphorus salt solution is 0.6:1;

[0119] mixing a complexing compound, an accelerator, a stabilizer, a wetting agent, a brightener and a pH buffer in the main tank with 1 / 3 water volume of the total volume of the tank to obtain a first mixed solution with a pH value of 9, then adding the first mixed solution to the nickel salt solution under stirring to obtain a second mixed solution, and then mixing the second mixed solution and the filtered phosphorus salt solution under stirring and diluting to the total volume of the main tank to obtain a chemical plating solution with a pH value of 8.5;

[0120] The complexing compound in the primary mixed solution comprises lactic acid solution (mass fraction of 80%), ammonium sulfate, ammonium citrate and potassium pyrophosphate in a mass ratio of 5:20:20:30; the accelerator is ammonia water, and the mass concentration of ammonia water in the primary mixed solution is 10 g / L; the stabilizer in the primary mixed solution comprises thiocyanogen, 3-5 isothiuronium propyl sulfonate, hexamethylene tetraanhydride and sodium thiosulfate in a mass ratio of 0.0008:10:1:0.001; the mass concentration of the wetting agent in the primary mixed solution is 50 g / L, and the wetting agent is sodium dodecyl benzene sulfonate; the brightener in the primary mixed solution is potassium iodate with a mass concentration of 4 mg / L; the pH buffer is boric acid; the volume ratio of the nickel salt solution, the primary mixed solution and the phosphorus salt solution is 1:1:1;

[0121] (b) placing the magnetron film into the electroless plating solution, starting the ultrasonic device, and performing a plating reaction at 30℃ for 0.5 min to obtain a nickel-phosphorus alloy layer;

[0122] The frequency of the ultrasonic device is 20 KHz, and the film pulling speed during the plating reaction is 3 m / min.

[0123] (3) performing a hole sealing treatment on the composite film obtained in step (2) by using a silane hole sealing process, and the specific steps include:

[0124] (c) mixing silane coupling agent (glycidoxypropyltrimethoxysilane), ethanol and water at room temperature (i.e. 25℃) in a volume ratio of 40:40:20, and performing a hydrolysis treatment under stirring for 70 h to obtain a hole sealing solution;

[0125] (d) soaking the composite film obtained in step (2) in the hole sealing solution for 1 min of hole sealing treatment;

[0126] (4) after the hole sealing treatment, performing a double-side electroplating acid copper process on the composite film, and then sequentially performing a double reverse flow water washing process, an anti-oxidation process, drying and a winding process, wherein the winding process includes slitting, to obtain the composite current collector.

[0127] Example 3

[0128] The preparation method of the composite current collector provided in this embodiment has the following disadvantages:

[0129] (1) unwinding the magnetron film and then performing water washing;

[0130] The magnetron film is a base film coated with a copper layer with a thickness of 40 nm on both sides, the base film is a PP film, and the square resistance of the magnetron film is 1.5Ω.

[0131] (2) adopting low phosphorus weak alkaline chemical nickel process on both sides of the surface of the magnetron film plated nickel phosphorus alloy layer, the specific steps include:

[0132] (a) with the total volume of 1 / 3 water amount heated to dissolve nickel salt (nickel chloride), the temperature of heating is 80℃, get the concentration of 40g / L of nickel salt solution; with the total volume of 1 / 3 water amount dissolved in the main tank phosphorus salt (sodium hypophosphite monohydrate), configuration concentration of 40g / L of phosphorus salt solution; the mass ratio of nickel ion in the nickel salt solution and the phosphate ion in the phosphorus salt solution is 0.3:1;

[0133] with the total volume of 1 / 3 water amount in the main tank will be complex compound, accelerant, stabilizer, wetting agent, brightener and pH buffer agent for the first time mixing, get the pH value of 9.5 of the first mixed solution, then the first mixed solution is added to the nickel salt solution under stirring conditions for the second mixing, get the second mixed solution, then the second mixed solution and stirring after filtration of the phosphorus salt solution for the third mixing, and dilution to the total volume of the main tank, get the pH value of 9 of the chemical plating solution;

[0134] wherein, the first mixed solution, complex compound includes mass ratio of 20:50:50:50 lactic acid solution (mass fraction of 80%), ammonium sulfate, citric acid ammonia and potassium pyrophosphate; the accelerator is ammonia water, the mass concentration of ammonia water in the first mixed solution is 30g / L; the first mixed solution, stabilizer includes mass ratio of 0.001:20:2:0.002 thiourea, 3-5 isothiouronium salt propane sulfonate, hexamethylene tetraphthalic anhydride and sodium thiosulfate; the mass concentration of wetting agent in the first mixed solution is 100g / L, and the wetting agent is sodium dodecyl benzene sulfonate; the brightener in the first mixed solution is copper sulfate with a mass concentration of 15mg / L; the pH buffer is boric acid; the volume ratio of the nickel salt solution, the first mixed solution and the phosphorus salt solution is 1:1:1;

[0135] (b) the magnetron film is placed in the chemical plating solution, the ultrasonic device is started, and the plating reaction is carried out at 65℃ for 3min, to obtain a nickel phosphorus alloy layer;

[0136] wherein, the frequency of the ultrasonic device is 40KHz, and the plating reaction is carried out at a film drawing speed of 6m / min;

[0137] (3) adopting silane sealing process for sealing treatment of the composite film obtained in step (2), the specific steps include:

[0138] (c) mixing silane coupling agent (glycidoxypropyltrimethoxysilane), ethanol and water at room temperature (i.e. 25℃) according to the volume ratio of 50:45:5, and carrying out hydrolysis treatment under stirring conditions for 80h, to obtain a sealing solution;

[0139] (d) soaking the composite film obtained in step (2) in the pore sealing solution to perform a pore sealing treatment for 3 min;

[0140] (4) after the pore sealing treatment, the composite film is washed with pure water, then subjected to a double-sided electroplating acid copper process, and then subjected to a double reverse flow water washing process, an oxidation resistance process, drying and a winding process, the winding process including slitting, to obtain the composite current collector.

[0141] Example 4

[0142] The difference between this example and Example 1 is that in step (a), the mass ratio of nickel ions in the nickel salt solution to phosphate ions in the phosphorus salt solution is 0.2:1.

[0143] The rest of the preparation method and parameters remain the same as in Example 1.

[0144] Example 5

[0145] The difference between this example and Example 1 is that in step (a), the mass ratio of nickel ions in the nickel salt solution to phosphate ions in the phosphorus salt solution is 0.7:1.

[0146] The rest of the preparation method and parameters remain the same as in Example 1.

[0147] Example 6

[0148] The difference between this example and Example 1 is that in step (a), the pH value of the electroless plating solution is 7.

[0149] The rest of the preparation method and parameters remain the same as in Example 1.

[0150] Example 7

[0151] The difference between this example and Example 1 is that in step (a), the pH value of the electroless plating solution is 10.

[0152] The rest of the preparation method and parameters remain the same as in Example 1.

[0153] Example 8

[0154] The difference between this example and Example 1 is that in step (b), no ultrasonic device is provided, i.e., no ultrasonic treatment is performed in the plating reaction.

[0155] The rest of the preparation method and parameters remain the same as in Example 1.

[0156] Example 9

[0157] The difference between this example and Example 1 is that in step (b), the temperature of the plating reaction is 20°C.

[0158] The remaining preparation method and parameters were kept consistent with Example 1.

[0159] Example 10

[0160] The difference between this example and Example 1 is that the plating reaction temperature in step (b) is 70°C.

[0161] The remaining preparation method and parameters were kept consistent with Example 1.

[0162] Example 11

[0163] The difference between this example and Example 1 is that the film drawing line speed in step (b) is 2 m / min.

[0164] The remaining preparation method and parameters were kept consistent with Example 1.

[0165] Example 12

[0166] The difference between this example and Example 1 is that the film drawing line speed in step (b) is 7 m / min.

[0167] The remaining preparation method and parameters were kept consistent with Example 1.

[0168] Example 13

[0169] The difference between this example and Example 1 is that the plating reaction time in step (b) is 10 s.

[0170] The remaining preparation method and parameters were kept consistent with Example 1.

[0171] Example 14

[0172] The difference between this example and Example 1 is that the plating reaction time in step (b) is 5 min.

[0173] The remaining preparation method and parameters were kept consistent with Example 1.

[0174] Comparative Example 1

[0175] The difference between this comparative example and Example 1 is that step (2) is not performed.

[0176] The remaining preparation method and parameters were kept consistent with Example 1.

[0177] Comparative Example 2

[0178] The difference between this comparative example and Example 1 is that step (3) is not performed.

[0179] The remaining preparation method and parameters were kept consistent with Example 1.

[0180] Comparative Example 3

[0181] The difference between the present comparative example and Example 1 is that steps (2) and (3) are not performed.

[0182] The remaining preparation method and parameters are consistent with Example 1.

[0183] Performance test

[0184] The composite current collectors prepared in the above examples and comparative examples are tested for density and elongation.

[0185] The testing method for density is as follows: the above prepared composite current collector sample is tightly attached to a common flat backlight (light brightness is 1200 mL) in a dark room, the sample has a length and width greater than 30 cm*30 cm of the backlight panel, and a photograph is taken at a vertical angle to show that the light transmission area is a non-dense area, and the non-light transmission area is a dense copper layer area; density = copper layer dense area / backlight panel area ≥ 90% qualified.

[0186] The testing method for elongation is as follows: the above composite current collector is baked at 150°C for 3 min, and then cut into a copper film strip with a width of 15 mm in the MD or TD direction, the edge cut of the strip-shaped test product cannot have a gap, and the burr and film surface cannot have a soft and hard injury. The running speed of the tensile testing machine is set to 50 mm / min, the stretching distance is 50 mm, the copper film strip of the test sample is placed in the upper and lower clamps so that the copper film strip is clamped and tensioned on the tensile testing machine, and the stretching test is carried out: MD or TD direction elongation ≥ 3% qualified.

[0187] The test results are shown in Table 1.

[0188] Table 1

[0189] Analysis:

[0190] From the above table, it can be seen that the chemical nickel-phosphorus plating process and the silane hole sealing process are introduced before the copper plating of the magnetic control film in the present application, which on the one hand increases the density and adhesion of the film surface, improves the qualified rate of the composite current collector, and on the other hand reduces the requirements for the thickness and square resistance of the magnetic control film layer, the square resistance is below 2Ω, and the thickness is 20-40 nm, which reduces the total energy and process difficulty of the magnetic control film production process, and simultaneously reduces the probability of the magnetic control film hole.

[0191] From Example 1 and Examples 4-5, if the mass ratio of nickel ions in the nickel plating solution and phosphate ions in the phosphorus plating solution is too small or too large, the plating film rate of the nickel-phosphorus alloy layer will be low, the plating layer will be dark, and the chemical plating layer will be too thin and not dense enough.

[0192] From Example 1 and Examples 6-7, it can be seen that if the pH value of the electroless plating solution is too small, the electroless plated layer will be too thin and not dense enough; if the pH value of the electroless plating solution is too large, the reaction will be too violent, the electroless plated layer will be rough and not dense enough.

[0193] From Example 1 and Example 8, it can be seen that if no ultrasonic treatment is performed during the plating reaction, the electroless plated layer will be too thin and not dense enough.

[0194] From Example 1 and Examples 9-10, it can be seen that if the temperature of the plating reaction is too low, the electroless plated layer will be too thin and not dense enough; if the temperature of the plating reaction is too high, the reaction will be too violent, the electroless plated layer will be rough and not dense enough.

[0195] From Example 1 and Examples 11-12, it can be seen that if the membrane drawing speed is too slow, the efficiency will be reduced; if the membrane drawing speed is too fast, the electroless plated layer will be too thin and not dense enough.

[0196] From Example 1 and Examples 13-14, it can be seen that if the plating reaction time is too long, the efficiency will be reduced; if the plating reaction time is too short, the electroless plated layer will be too thin and not dense enough.

[0197] From Example 1 and Comparative Example 1, it can be seen that if the electroless nickel-phosphorus process is not used to plate a nickel-phosphorus alloy layer on the surfaces of both sides of the magnetic control film, the density will not be enough.

[0198] From Example 1 and Comparative Example 2, it can be seen that if the silane hole sealing process is not used for hole sealing treatment, the density will not be enough.

[0199] From Example 1 and Comparative Example 3, it can be seen that if neither the electroless nickel-phosphorus process nor the silane hole sealing process is used, the density will not be enough and the elongation rate cannot be significantly improved.

[0200] The applicant declares that the process method of the present application is illustrated by the above examples, but the present application is not limited to the above process steps, i.e. it does not mean that the present application must rely on the above process steps to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the materials selected by the present application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a composite current collector, comprising the following steps: (1) unwinding a magnetron film and performing pretreatment; (2) plating a nickel-phosphorus alloy layer on both sides of the magnetron film by using a chemical nickel-phosphorus plating process; (3) performing a silane sealing process on the composite film obtained in step (2) to seal the pores, the specific steps of the silane sealing process comprising: performing sealing treatment on the obtained composite film by using a sealing solution; (4) performing double-sided copper plating on the composite film after the sealing treatment, and then performing post-treatment to obtain the composite current collector.

2. The production method according to claim 1, wherein, The pretreatment in step (1) comprises water washing; The magnetron film in step (1) comprises a base film and a copper layer arranged on both sides of the base film; The square resistance of both sides of the magnetron film in step (1) is 1-2 Ω; The thickness of the copper layer on one side is 20-40 nm.

3. The production method according to claim 1, wherein The chemical nickel-phosphorus plating process in step (2) is a low-phosphorus weak-alkaline chemical nickel process, and the specific steps of the low-phosphorus weak-alkaline chemical nickel process comprising: (a) mixing a nickel plating solution, a complexing compound, an accelerator, a stabilizer, a wetting agent, and a phosphorus plating solution to obtain a chemical plating solution; (b) placing the magnetron film in the chemical plating solution to perform plating reaction to obtain a nickel-phosphorus alloy layer.

4. The production method according to claim 3, wherein The nickel plating solution in step (a) comprises a nickel salt, and the nickel salt comprises any one or a combination of at least two of nickel chloride, nickel sulfate, or nickel acetate; The concentration of the nickel plating solution in step (a) is 20-40 g / L; The phosphorus plating solution in step (a) comprises a phosphorus salt, and the phosphorus salt comprises sodium hypophosphite monohydrate and / or sodium dihydrogen phosphate; The concentration of the phosphorus plating solution in step (a) is 10-40 g / L; The mass ratio of nickel ions in the nickel plating solution to phosphate ions in the phosphorus plating solution in step (a) is (0.3-0.6):

1.

5. The method of making according to claim 3, wherein, The specific steps of the mixing in step (a) comprising: mixing the complexing compound, the accelerator, the stabilizer, and the wetting agent to obtain a first mixed solution, then mixing the first mixed solution and the nickel plating solution to obtain a second mixed solution, and then mixing the second mixed solution and the phosphorus plating solution to obtain a third mixed solution; The complexing compound comprises any one or a combination of at least two of an ammonium salt, a citrate salt, or potassium pyrophosphate; The complexing compound further comprises a lactic acid solution; The accelerator comprises any one or a combination of at least two of ammonia water, a fatty acid, propionic acid, succinic acid, malic acid, triethanolamine, a fluoride, or a lithium salt; The mass concentration of the accelerator in the first mixed solution is 10-30 g / L; The stabilizer comprises any one or a combination of at least two of thiourea, 3-5 isothiuronium propanesulfonate, phthalic anhydride, hexamethylene tetraphthalic anhydride, mercaptobenzothiazole, xanthate, or sodium thiosulfate; The mass concentration of the wetting agent in the first mixed solution is 50-100 g / L; A brightener is further added in the process of the first mixing, and the brightener comprises copper sulfate and / or potassium iodate; A pH buffer is further added in the process of the first mixing; The pH value of the first mixed solution is 7.5-10.

6. The production method according to claim 5, wherein The volume ratio of the nickel plating solution, the first mixed solution and the phosphorus plating solution is (0.8-1.2):(0.8-1.2):(0.8-1.2); The pH value of the electroless plating solution in step (a) is 8-9.

5.

7. The production method according to claim 3, wherein The plating reaction in step (b) is accompanied by ultrasonic, and the frequency of the ultrasonic is 20-40 KHz; The temperature of the plating reaction in step (b) is 30-65℃; The film drawing speed during the plating reaction in step (b) is 3-6 m / min; The time of the plating reaction in step (b) is 0.5-3 min.

8. The production method according to claim 1, wherein The preparation of the pore sealing solution comprises mixing silane coupling agent, ethanol and water, and performing hydrolysis treatment; The volume ratio of the silane coupling agent, ethanol and water is (40-50):(40-45):(5-20); The temperature of the hydrolysis treatment is normal temperature, and the time of the hydrolysis treatment is 70-80 h; The time of the pore sealing treatment is 1-3 min.

9. The production method according to claim 1, wherein The double-sided copper plating method in step (4) comprises double-sided electroplating of acid copper; The post-treatment in step (4) comprises sequentially performing water washing, anti-oxidation process, drying and winding processes.

10. The production method according to claim 1, wherein, The preparation method comprises the following steps: (1) unwinding the magnetron film, and then performing water washing; The magnetron film is a base film coated with copper layers with a thickness of 20-40 nm on both sides; (2) using low-phosphorus weak alkaline chemical nickel process to plate nickel-phosphorus alloy layers on both sides of the magnetron film, and the specific steps comprise: (a) heating and dissolving nickel salt in water at 60-80℃ to obtain a nickel salt solution with a concentration of 20-40 g / L; preparing a phosphorus salt solution with a concentration of 10-40 g / L; the mass ratio of nickel ions in the nickel salt solution to phosphate ions in the phosphorus salt solution is (0.3-0.6):1; mixing a complexing compound, an accelerator, a stabilizer, a wetting agent, a brightener and a pH buffer to obtain a first mixed solution with a pH value of 7.5-10, then mixing the first mixed solution and the nickel salt solution to obtain a second mixed solution, and then mixing the second mixed solution and the phosphorus salt solution to obtain an electroless plating solution with a pH value of 8-9.5; The complexing compound in the primary mixed solution comprises lactic acid solution, ammonium salt, citrate and potassium pyrophosphate in a mass ratio of (5-20):(20-50):(20-50):(30-50); the accelerator is ammonia water, and the mass concentration of ammonia water in the primary mixed solution is 10-30 g / L; the stabilizer in the primary mixed solution comprises thiourea, 3-5 isothiuronium salt propane sulfonate, hexamethylene tetra-mellitic anhydride and sodium thiosulfate in a mass ratio of (0.0008-0.001):(10-20):(1-2):(0.001-0.002); the mass concentration of the wetting agent in the primary mixed solution is 50-100 g / L; the brightener in the primary mixed solution is copper sulfate with a mass concentration of 10-20 mg / L or potassium iodate with a mass concentration of 2-6 mg / L; the pH buffer is boric acid or ammonia water; the volume ratio of the nickel salt solution, the primary mixed solution and the phosphorus salt solution is (0.8-1.2):(0.8-1.2):(0.8-1.2); (b) placing the magnetron film into the electroless plating solution to perform a plating reaction at 30-65 ℃ for 0.5-3 min to obtain a nickel-phosphorus alloy layer; In the process of the plating reaction, ultrasonic waves are used, and the frequency of the ultrasonic waves is 20-40 KHz; in the process of the plating reaction, the film pulling speed is 3-6 m / min; (3) performing a hole sealing process on the composite film obtained in step (2) by using a silane hole sealing process, and the specific steps include: (c) mixing silane coupling agent, ethanol and water at room temperature in a volume ratio of (40-50):(40-45):(5-20) and performing hydrolysis treatment under stirring for 70-80 h to obtain a hole sealing solution; (d) immersing the composite film obtained in step (2) in the hole sealing solution to perform hole sealing treatment for 1-3 min; (4) after the hole sealing treatment, washing the composite film, performing a double-side acid copper plating process, then sequentially performing a double reverse flow washing process, an anti-oxidation process, drying and a winding process, and the winding process includes slitting to obtain the composite current collector.

11. A composite current collector prepared by the production method according to any one of claims 1 to 10, wherein The elongation of the composite current collector in the MD direction is ≥9%, and the elongation in the TD direction is ≥5%. The square resistance of the composite current collector is ≤2 Ω.

12. A secondary battery, wherein, The secondary battery comprises the composite current collector prepared by the preparation method according to any one of claims 1-10 or the composite current collector according to claim 11.

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