Cleaning method of electrochemical current collector, electrochemical current collector obtained by cleaning method and application of electrochemical current collector

Abstract

The invention provides a cleaning method of an electrochemical current collector, the electrochemical current collector obtained by the cleaning method and application of the electrochemical current collector, and relates to the field of aluminum foil current collectors of supercapacitors and lithium batteries. The cleaning method of the electrochemical current collector comprises the following steps: placing an electrochemical current collector subjected to electrochemical etching in a weak acid solution, and carrying out acid pickling to obtain an electrochemical current collector subjected to acid pickling; and putting the acid-washed electrochemical current collector into a zinc salt solution, and treating to form a zinc-aluminum alloy film, thereby obtaining the electrochemical current collector with the protective film. According to the invention, weak acid is used for cleaning the etched electrochemical current collector, so that micro-nano holes of the electrochemical current collector can be protected from being damaged, and an effect of cleaning aluminum powder can be achieved; furthermore, zinc and aluminum can form a zinc-aluminum alloy, so that the negative pressure effect of chloride ions on aluminum in a solution can be reduced, the chloride ions in the electrochemical etching aluminum foil can be better cleaned, and the zinc-aluminum alloy formed on the surface layer can keep the electrochemical aluminum foil current collector not easy to corrode.

Description

Technical Field

[0001] This invention relates to the field of electrochemical current collectors, and in particular to a cleaning method for electrochemical current collectors, the resulting electrochemical current collectors, and their applications. Background Technology

[0002] Lithium-ion batteries and supercapacitors, as efficient and environmentally friendly energy storage devices, are widely used in electric vehicles, mobile communications, wind power generation, energy storage systems, and other fields. Internal resistance is an important performance indicator for lithium-ion batteries and supercapacitors.

[0003] Internal resistance refers to the resistance encountered by current flowing through the interior of a lithium battery or supercapacitor during discharge or charging. The magnitude of internal resistance directly affects the performance of lithium batteries and supercapacitors, including output power, cycle life, and temperature characteristics.

[0004] The bonding resistance between the electrochemically etched aluminum foil and the coating is one of the factors affecting the internal resistance of lithium batteries and supercapacitors. Currently, after the electrochemical etching process to create micro- and nano-pores, strong acids are generally used to clean the aluminum powder in the micro- and nano-pores. However, because the freshly etched aluminum foil lacks an oxide layer and is very reactive, using strong acids to clean the aluminum powder can also corrode the already formed micro- and nano-pores. Furthermore, strong acids can only dilute the chloride ion content and cannot reduce the negative pressure effect of chloride ions on the aluminum foil, thus requiring prolonged cleaning with strong acids. This creates a vicious cycle of contradictions. If the aluminum powder remaining in the nano-pores after etching is not thoroughly cleaned, chloride ions used for etching the aluminum foil will still remain in the nano-pores. Impurities in the current collector itself can easily damage the SEM film between the etched aluminum foil and the coating.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a cleaning method for electrochemical current collectors, the resulting electrochemical current collector, and its applications. The cleaning method of this invention can effectively remove aluminum powder, chloride ions, and other elemental impurities from electrochemically etched foils, protecting the etched pits of low-purity aluminum foil from damage and forming an acid-resistant zinc-aluminum alloy surface layer. This method does not require additional investment in large-scale equipment, is suitable for production, is simple to operate, and has high production efficiency. It effectively improves problems such as high coating resistance and low peel strength between the etched aluminum foil and the coating slurry after electrochemical etching, thereby ensuring product quality and service life.

[0007] To achieve the above objectives, the following technical solution is proposed:

[0008] In a first aspect, the present invention provides a cleaning method for an electrochemical current collector, the cleaning method comprising:

[0009] The electrochemically etched electrochemical current collector is placed in a weak acid solution and acid-washed to obtain the acid-washed electrochemical current collector.

[0010] The acid-washed electrochemical current collector is immersed in a zinc salt solution, washed, and then calcined to form a zinc-aluminum alloy film, thus obtaining an electrochemical current collector with a protective film.

[0011] Preferably, the electrochemically etched current collector is an electrochemically etched aluminum foil current collector; and the surface of the electrochemically etched aluminum foil current collector has micro-nano pores; wherein, aluminum powder remaining after electrochemical etching exists in the micro-nano pores; and chloride ions remaining after electrochemical etching exist on the electrochemically etched aluminum foil current collector.

[0012] Preferably, the thickness of the electrochemically etched aluminum foil current collector is 15–30 μm.

[0013] Preferably, the porosity of the electrochemically etched aluminum foil current collector is 30-60%, and the pore size of the electrochemically etched aluminum foil current collector is 0.1-2.0 μm.

[0014] Preferably, the weak acid includes any one or a combination of at least two of oxalic acid, acetic acid, lactic acid, boric acid, succinic acid, citric acid or tartaric acid, with oxalic acid being the most preferred.

[0015] Preferably, the mass percentage of the weak acid in the weak acid solution is 5-20%.

[0016] Preferably, the pickling temperature is 40–60°C.

[0017] Preferably, the pickling time is 20 to 80 seconds.

[0018] Preferably, the process specifically includes the following steps:

[0019] The acid-washed electrochemical current collector is immersed in a zinc salt solution, washed, and then calcined to form a zinc-aluminum alloy film.

[0020] Preferably, the zinc salt includes any one or a combination of at least two of zinc sulfate, zinc oxalate, zinc citrate, zinc tartrate, or zinc acetate, with zinc sulfate being the most preferred.

[0021] Preferably, the zinc salt content in the zinc salt solution is 0.1% to 2% by mass.

[0022] Preferably, the soaking temperature is 30–60°C.

[0023] Preferably, the soaking time is 20 to 120 seconds.

[0024] Preferably, the calcination is carried out in the presence of a protective gas.

[0025] Preferably, the protective gas comprises nitrogen and / or argon.

[0026] Preferably, the calcination temperature is 300–500°C.

[0027] Preferably, the calcination time is 60 to 180 minutes.

[0028] Preferably, the calcination is carried out using a gradient heating segmented calcination procedure; wherein the gradient heating segmented calcination procedure includes, in sequence: calcination at 380-390℃ for 10-30 min, calcination at 390-410℃ for 20-40 min, calcination at 440-460℃ for 20-40 min, and calcination at 470-490℃ for 10-30 min.

[0029] Preferably, the pickling process further includes the following steps:

[0030] The acid-washed electrochemical current collector is placed in a weak alkaline solution and reverse-current is applied to obtain an alkaline-washed electrochemical current collector.

[0031] Preferably, the weak base includes any one or a combination of at least two of ammonium adipate, ammonium glutarate, ammonium sebacate, ammonium formate, or ammonium acetate, with ammonium adipate being the most preferred.

[0032] Preferably, the reverse voltage is 1–20V and the current density is 1–50mA / cm². 2 .

[0033] Preferably, the reverse power-on processing time is 20 to 120 seconds.

[0034] Preferably, the electrode plate used for reverse power application includes any one of stainless steel electrode plate, titanium electrode plate, or graphite electrode plate.

[0035] Preferably, the process further includes the following steps:

[0036] An electrochemical current collector with a protective film is placed in a phosphate solution and then cleaned to form a protective film with phosphate ions, thus obtaining an electrochemical current collector with a composite protective film.

[0037] Preferably, the phosphate includes any one or a combination of at least two of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, or ammonium phosphate, with ammonium dihydrogen phosphate being the most preferred.

[0038] Preferably, the phosphate solution contains 0.1% to 2% phosphate by mass.

[0039] Preferably, the temperature of the post-treatment cleaning is 48–60°C.

[0040] Preferably, the post-treatment cleaning time is 30-40 seconds.

[0041] In a second aspect, the present invention provides an electrochemical current collector having a protective film; and the electrochemical current collector is obtained by a cleaning method for electrochemical current collectors as described in the first aspect.

[0042] Thirdly, the present invention provides an application of the electrochemical current collector as described in the second aspect in the preparation of supercapacitors or lithium batteries.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The cleaning method described in this invention can efficiently remove elemental impurities, aluminum powder and residual chloride ions from the etched foil, and the zinc-aluminum alloy formed on the surface can keep the electrochemical aluminum foil current collector from being corroded; it can also protect the bulk fluid from being corroded or oxidized after it is made into a lithium battery or supercapacitor.

[0045] (2) The cleaning method described in this invention effectively improves the problems of high coating resistance and low peel force between the etched aluminum foil and the coating slurry after electrochemical etching, thereby ensuring the quality and service life of the product.

[0046] (3) The cleaning method described in this invention does not require additional cost investment in large equipment, is suitable for production, is easy to operate, and has high production efficiency. Detailed Implementation

[0047] The embodiments and examples of the present invention will be described in detail below. However, those skilled in the art will understand that the following embodiments and examples are for illustrative purposes only and should not be considered as limiting the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0048] In a first aspect, the present invention provides a cleaning method for an electrochemical current collector, the cleaning method comprising:

[0049] The electrochemically etched electrochemical current collector is placed in a weak acid solution and acid-washed to obtain the acid-washed electrochemical current collector.

[0050] The acid-washed electrochemical current collector is placed in a zinc salt solution for treatment to form a zinc-aluminum alloy film, thus obtaining an electrochemical current collector with a protective film.

[0051] In this invention, the cleaning method removes elemental impurities, aluminum powder, and residual chloride ions from the electrochemically etched foil and forms a more corrosion-resistant zinc-aluminum alloy on the surface of the electrochemically etched aluminum foil to reduce the bonding resistance between the electrochemically etched aluminum foil and the coating. First, a weakly acidic solution is used for cleaning, which is suitable for various grades of aluminum foil and can protect the micro-nano porous morphology of the etched aluminum foil from acid damage. That is, the weak acid cleaning of aluminum powder after electrochemical current collector etching will not damage the micro-nano etched pores, thus protecting the micro-nano pore structure. Then, a zinc salt solution is used for treatment, which can form a zinc-aluminum alloy and reduce the negative pressure effect formed by chloride ions and aluminum, further effectively cleaning chloride ions. The zinc-aluminum alloy protective film formed on the surface can maintain the anti-corrosion and anti-acid effect of the electrochemical aluminum foil current collector. In particular, it can protect the fluid from corrosion or oxidation when it is later made into lithium batteries or supercapacitors.

[0052] As an optional implementation, the electrochemically etched electrochemical current collector is an electrochemically etched aluminum foil current collector; and the surface of the electrochemically etched aluminum foil current collector has micro-nano pores; wherein, aluminum powder remaining after electrochemical etching exists in the micro-nano pores; and chloride ions remaining after electrochemical etching exist on the electrochemically etched aluminum foil current collector.

[0053] As an optional implementation, the mass percentage of aluminum powder remaining after electrochemical etching in the micro / nano pores is 0.1% to 5%, for example, it can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. (It should be noted that the mass percentage of residual aluminum powder here refers to the amount of residual aluminum powder before cleaning).

[0054] As an optional implementation, the mass percentage of residual chloride ions in the micro / nanopores after electrochemical etching is 0.0005% to 0.0020%, for example, 0.0005%, 0.0006%, 0.0008%, 0.0010%, 0.0012%, 0.0014%, 0.0016%, 0.0018%, 0.0020%, etc. (It should be noted that the mass percentage of residual chloride ions here refers to the amount of residual chloride ions before cleaning).

[0055] As an optional implementation, the thickness of the electrochemically etched aluminum foil current collector is 15-30 μm, for example, it can be 15 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 25 μm, 26 μm, 28 μm, 30 μm, etc.

[0056] As an optional implementation, the porosity of the etched layer portion of the electrochemically etched aluminum foil current collector is 30% to 60%, for example, it can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc.

[0057] As an optional implementation, the pore size of the electrochemically etched aluminum foil current collector is 0.1 to 2.0 μm, for example, it can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, etc.

[0058] As an optional implementation, the electrochemically etched aluminum foil current collector includes an electrochemically etched aluminum foil current collector for supercapacitors or an electrochemically etched aluminum foil current collector for lithium batteries.

[0059] As an optional implementation, the purity of the aluminum foil is 99.99% or less, for example, it can be 99.95%, 99.90%, 99.85%, 99.80%, 99.75%, 99.70%, 99.65%, 99.60%, 99.55%, 99.50%, etc.

[0060] As an optional implementation, the aluminum foil current collector includes aluminum foil with a purity grade of 1090 or lower, such as aluminum foil with grades 1070, 1090, etc.

[0061] It should be noted that the present invention first uses a weak acid to clean the aluminum powder remaining after electrochemical etching, mainly for aluminum foil that is not 99.99% pure, such as aluminum foil with grades 1070 and 1090.

[0062] As an optional implementation, the weak acid includes any one or a combination of at least two of oxalic acid, acetic acid, lactic acid, boric acid, succinic acid, citric acid, or tartaric acid.

[0063] In a preferred embodiment, the weak acid is oxalic acid.

[0064] As an optional implementation, the mass percentage of the weak acid in the weak acid solution is 5% to 20%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0065] As an optional implementation, the pickling temperature is 40-60°C, for example, it can be 40°C, 42°C, 44°C, 45°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, etc.

[0066] As an optional implementation, the pickling time is 20 to 80 seconds, for example, it can be 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, 55 seconds, 60 seconds, 65 seconds, 70 seconds, 75 seconds, 80 seconds, etc.

[0067] As an optional implementation, the process specifically includes the following steps:

[0068] The acid-washed electrochemical current collector is immersed in a zinc salt solution, washed, and then calcined to form a zinc-aluminum alloy film.

[0069] As an optional implementation, the zinc salt includes any one or a combination of at least two of zinc sulfate, zinc oxalate, zinc citrate, zinc tartrate, or zinc acetate.

[0070] In a preferred embodiment, the zinc salt is zinc sulfate.

[0071] As an optional implementation, the zinc salt solution contains 0.1% to 2% by mass, for example, 0.1%, 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, etc.

[0072] As an optional implementation, the soaking temperature is 30 to 60°C, for example, it can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, etc.

[0073] As an optional implementation, the soaking time is 20 to 120 seconds, for example, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 110 seconds, 120 seconds, etc.

[0074] As an optional implementation, the calcination is carried out in the presence of a protective gas.

[0075] As an optional implementation, the protective gas includes nitrogen and / or argon.

[0076] As an optional implementation, the calcination temperature is 300-500℃, for example, it can be 300℃, 320℃, 340℃, 350℃, 360℃, 380℃, 400℃, 420℃, 440℃, 450℃, 460℃, 480℃, 500℃, etc.

[0077] As an optional implementation, the calcination time is 60 to 180 minutes, for example, it can be 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes, 130 minutes, 140 minutes, 150 minutes, 160 minutes, 170 minutes, 180 minutes, etc.

[0078] As an optional implementation, the calcination is carried out using a gradient heating segmented calcination process.

[0079] As an optional implementation, the calcination gradient heating segmented calcination process sequentially includes:

[0080] ① Calcination at 380~390℃ for 10~30 min;

[0081] ② Calcination at 390~410℃ for 20~40 min;

[0082] ③ Calcination at 440~460℃ for 20~40 min;

[0083] ④ Calcination at 470~490℃ for 10~30min.

[0084] As an optional implementation, the temperature in the calcination process ① is 380-390℃, for example, it can be 380℃, 381℃, 382℃, 383℃, 384℃, 385℃, 386℃, 387℃, 388℃, 389℃, 390℃, etc.

[0085] As an optional implementation, the time in the calcination process ① is 10 to 30 minutes, for example, it can be 10 minutes, 12 minutes, 14 minutes, 15 minutes, 16 minutes, 18 minutes, 20 minutes, 22 minutes, 24 minutes, 25 minutes, 26 minutes, 28 minutes, 30 minutes, etc.

[0086] As an optional implementation, the temperature in ② of the calcination process is 390 to 410°C, for example, it can be 390°C, 392°C, 394°C, 396°C, 398°C, 400°C, 402°C, 404°C, 406°C, 408°C, 410°C, etc.

[0087] As an optional implementation, the time in step ② of the calcination process is 20 to 40 minutes, for example, it can be 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes, 40 minutes, etc.

[0088] As an optional implementation, the temperature in ③ of the calcination process is 440 to 460°C, for example, it can be 440°C, 442°C, 444°C, 446°C, 448°C, 450°C, 452°C, 454°C, 456°C, 458°C, 460°C, etc.

[0089] As an optional implementation, the time in ③ of the calcination process is 20 to 40 minutes, for example, it can be 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes, 40 minutes, etc.

[0090] As an optional implementation, the temperature in ④ of the calcination process is 470-490℃, for example, it can be 470℃, 472℃, 474℃, 476℃, 478℃, 480℃, 482℃, 484℃, 486℃, 488℃, 490℃, etc.

[0091] As an optional implementation, the time in step ④ of the calcination process is 10 to 30 minutes, for example, it can be 10 minutes, 12 minutes, 14 minutes, 15 minutes, 16 minutes, 18 minutes, 20 minutes, 22 minutes, 24 minutes, 25 minutes, 26 minutes, 28 minutes, 30 minutes, etc.

[0092] In a preferred embodiment, the pickling process further includes the following steps:

[0093] The acid-washed electrochemical current collector is placed in a weak alkaline solution and reverse-current is applied to obtain an alkaline-washed electrochemical current collector.

[0094] In this invention, a weak alkaline solution is used for reverse electrostatic discharge (RED) to clean residual impurities in the electrochemical current collector. Furthermore, by controlling the current and voltage, RED can coordinate their effects to remove crystal defects in the etched foil material, including vacancies, interstitial atoms, impurities, solute atoms, and dislocations. Crystal defects have higher energy than other locations, making them more susceptible to electrolyte reactions. This can damage the SEM film at these sites, leading to increased leakage current, higher internal resistance, and lower voltage, ultimately affecting the overall battery performance and lifespan. RED can remove crystal defects and impurities from the material, reducing its internal resistance.

[0095] As an optional implementation, the weak base includes any one or a combination of at least two of ammonium adipate, ammonium glutarate, ammonium sebacate, ammonium formate, or ammonium acetate.

[0096] In a preferred embodiment, the weak base is ammonium adipate.

[0097] As an optional implementation, the reverse voltage is 1–20V, for example, it can be 1V, 2V, 4V, 5V, 6V, 8V, 10V, 12V, 14V, 15V, 16V, 18V, 20V, etc., and the current density is 1–50mA / cm². 2 For example, it could be 1mA / cm 2 5mA / cm 2 10mA / cm 2 15mA / cm 2 20mA / cm 2 25mA / cm 2 30mA / cm 2 35mA / cm 2 40mA / cm 2 45mA / cm 2 50mA / cm 2 wait.

[0098] As an optional implementation, the reverse power-on processing time is 20 to 120 seconds, for example, it can be 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 110 seconds, 120 seconds, etc.

[0099] As an optional implementation, the electrode plate used for reverse power application includes any one of stainless steel electrode plate, titanium electrode plate, or graphite electrode plate.

[0100] As an optional implementation, the process further includes the following steps:

[0101] An electrochemical current collector with a protective film is placed in a phosphate solution and then cleaned to form a protective film with phosphate ions, thus obtaining an electrochemical current collector with a composite protective film.

[0102] In this invention, after forming a zinc-aluminum alloy film, a protective film with phosphate ions is formed by post-treatment cleaning in a phosphate solution, the purpose of which is to improve the corrosion resistance of the aluminum foil.

[0103] As an optional implementation, the phosphate includes any one or a combination of at least two of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, or ammonium phosphate.

[0104] In a preferred embodiment, the phosphate is ammonium dihydrogen phosphate.

[0105] As an optional implementation, the phosphate solution contains 0.1% to 2% phosphate by mass, for example, 0.1%, 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, etc.

[0106] As an optional implementation, the temperature of the post-treatment cleaning is 48-60°C, for example, 48°C, 50°C, 52°C, 54°C, 55°C, 56°C, 58°C, 60°C, etc.

[0107] As an optional implementation, the post-processing cleaning time is 30 to 40 seconds, for example, 30 seconds, 32 seconds, 34 seconds, 35 seconds, 36 seconds, 38 seconds, 40 seconds, etc.

[0108] As an optional implementation, the cleaning method for the electrochemical current collector includes the following steps:

[0109] S1, weak acid pickling:

[0110] The electrochemically etched electrochemical current collector is placed in a weak acid solution and acid-washed to obtain the acid-washed electrochemical current collector.

[0111] S2, weak base reverse electrolysis:

[0112] The S1 acid-washed electrochemical current collector was placed in a weak alkaline solution and reverse-current was applied to obtain an alkaline-washed electrochemical current collector.

[0113] S3. Preparation of zinc-aluminum alloy film:

[0114] The electrochemical current collector after S2 alkaline washing is placed in a zinc salt solution for treatment to form a zinc-aluminum alloy film, thus obtaining an electrochemical current collector with a protective film.

[0115] As an optional implementation, the preparation of the zinc-aluminum alloy membrane in step S3 also includes pure water rinsing in step S4:

[0116] The S3 electrochemical current collector with a protective film is washed with pure water and then dried to obtain the final electrochemical current collector with a protective film.

[0117] As an optional implementation, the cleaning method for the electrochemical current collector includes the following steps:

[0118] S1', weak acid pickling:

[0119] The electrochemically etched electrochemical current collector is placed in a weak acid solution and acid-washed to obtain the acid-washed electrochemical current collector.

[0120] S2', Preparation of zinc-aluminum alloy film:

[0121] The electrochemical current collector after S2' acid washing is placed in a zinc salt solution for treatment to form a zinc-aluminum alloy film, thus obtaining an electrochemical current collector with a protective film.

[0122] S3', Preparation of composite protective film:

[0123] The electrochemical current collector with a protective film S3' is placed in a phosphate solution and then cleaned to form a protective film with phosphate ions, thus obtaining an electrochemical current collector with a composite protective film.

[0124] As an optional implementation, the preparation of the zinc-aluminum alloy membrane in step S3' further includes S4' pure water rinsing:

[0125] The electrochemical current collector with composite protective film S3' is washed with pure water and then dried to obtain the final electrochemical current collector with protective film.

[0126] In a second aspect, the present invention provides an electrochemical current collector having a protective film; and the electrochemical current collector is obtained by a cleaning method for electrochemical current collectors as described in the first aspect.

[0127] Thirdly, the present invention provides an application of the electrochemical current collector as described in the second aspect in the preparation of supercapacitors or lithium batteries.

[0128] Based on the present invention, the aluminum foil is used as a positive current collector for lithium batteries and supercapacitors to reduce the bonding resistance between the electrochemically etched aluminum foil and the coating.

[0129] The present invention will be further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0130] Example 1

[0131] This embodiment provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0132] S1. Take aluminum foil of grade 1070 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 30%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 9% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 60s and the solution temperature is 52℃.

[0133] S2. The electrochemical current collector obtained after S1 is placed in a 0.3% zinc sulfate solution (solvent is pure water) and immersed at 45°C for 60 seconds. After rinsing with pure water, the sample is placed in a tube furnace under argon atmosphere protection. The tube furnace is set with stepped calcination (in sequence: calcination at 385°C for 20 min, calcination at 400°C for 30 min, calcination at 450°C for 30 min, and calcination at 480°C for 20 min) to form a surface zinc-aluminum alloy. This step is to clean the residual chloride ions in the aluminum foil and generate a zinc-aluminum protective film.

[0134] S3. After washing the etched aluminum foil obtained from S2 with pure water, dry it in a 100℃ oven and remove it to obtain an electrochemical current collector with a protective film.

[0135] Example 2

[0136] This embodiment provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0137] S1. Take aluminum foil of grade 1070 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 30%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 9% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 60s and the solution temperature is 52℃.

[0138] S2. The electrochemical current collector obtained after treatment S1 is placed in a 7% (w / w) ammonium adipate solution (solvent: pure water). A graphite electrode plate is installed in the tank. Reverse current is applied to clean residual chloride ions from the electrochemical current collector. The current density during this reverse current application is set to 10 mA / cm². 2 The voltage was set to 5V, the processing time to 60s, and the solution temperature to 65℃.

[0139] S3. The electrochemical current collector obtained after S2 treatment is placed in a 0.3% zinc sulfate solution (solvent is pure water) and immersed at 45°C for 60 seconds. After rinsing with pure water, the sample is placed in a tube furnace under argon atmosphere protection. The tube furnace is set with stepped calcination (sequentially including: calcination at 385°C for 20 min, calcination at 400°C for 30 min, calcination at 450°C for 30 min, and calcination at 480°C for 20 min) to form a surface zinc-aluminum alloy. This step is to clean the residual chloride ions in the aluminum foil and generate a zinc-aluminum protective film.

[0140] S4. After washing the etched aluminum foil obtained from S3 with pure water, dry it in a 100℃ oven and remove it to obtain an electrochemical current collector with a protective film.

[0141] Example 3

[0142] This embodiment provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0143] S1. Take aluminum foil of grade 1070 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 30μm, porosity of 30% and pore size of 0.1-2μm). After the current collector is cleaned with pure water, it is placed in a 12% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 40s and the solution temperature is 52℃.

[0144] S2. The electrochemical current collector obtained after treatment S1 is placed in a 9% (w / w) ammonium adipate solution (using pure water as the solvent). A graphite electrode plate is placed in the tank, and reverse current is applied to clean residual chloride ions in the electrochemical current collector and to generate a zinc-aluminum protective film. The current density during this reverse current application is set to 10 mA / cm². 2 The voltage was set to 5V, the processing time to 40s, and the solution temperature to 65℃.

[0145] S3. The electrochemical current collector obtained after S2 treatment is placed in a 0.5% zinc sulfate solution (solvent is pure water) and immersed at 52°C for 40 seconds. After rinsing with pure water, the sample is placed in a tube furnace under argon atmosphere protection. The tube furnace is set with stepped calcination (in sequence: calcination at 385°C for 20 min, calcination at 400°C for 30 min, calcination at 450°C for 30 min, and calcination at 480°C for 20 min) to form a surface zinc-aluminum alloy. This step is to clean the residual chloride ions in the aluminum foil and generate a zinc-aluminum protective film.

[0146] S4. After washing the etched aluminum foil obtained from S3 with pure water, dry it in a 100℃ oven and remove it to obtain an electrochemical current collector with a protective film.

[0147] Example 4

[0148] This embodiment provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0149] S1. Take aluminum foil of grade 1090 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 50%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 12% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 40s and the solution temperature is 52℃.

[0150] S2. The electrochemical current collector obtained after treatment S1 is placed in a 9% (w / w) ammonium adipate solution (solvent: pure water). A graphite electrode plate is installed in the tank. Reverse current is applied to clean residual chloride ions from the electrochemical current collector. The current density during this reverse current application is set to 10 mA / cm². 2 The voltage was set to 5V, the processing time to 40s, and the solution temperature to 65℃.

[0151] S3. The electrochemical current collector obtained after S2 treatment is placed in a 0.5% zinc sulfate solution (solvent is pure water) and immersed at 52°C for 40 seconds. After rinsing with pure water, the sample is placed in a tube furnace under argon atmosphere protection. The tube furnace is set with stepped calcination (in sequence: calcination at 385°C for 20 min, calcination at 400°C for 30 min, calcination at 450°C for 30 min, and calcination at 480°C for 20 min) to form a surface zinc-aluminum alloy. This step is to clean the residual chloride ions in the aluminum foil and generate a zinc-aluminum protective film.

[0152] S4. After washing the etched aluminum foil obtained from S3 with pure water, dry it in a 100℃ oven and remove it to obtain an electrochemical current collector with a protective film.

[0153] Example 5

[0154] This embodiment provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0155] S1. Take aluminum foil of grade 1090 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 50%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 15% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 30s and the solution temperature is 48℃.

[0156] S2. The electrochemical current collector obtained after treatment S1 is placed in a 12% (w / w) ammonium adipate solution (using pure water as the solvent). A graphite electrode plate is installed in the tank, and reverse current is applied to clean residual chloride ions from the electrochemical current collector. The current density during this reverse current application is set to 10 mA / cm². 2 The voltage was set to 5V, the processing time to 30s, and the solution temperature to 55℃.

[0157] S3. The electrochemical current collector obtained after S2 treatment is placed in a 1.5% zinc sulfate solution (solvent is pure water) and immersed at 48°C for 30 seconds. After rinsing with pure water, the sample is placed in a tube furnace under argon atmosphere protection. The tube furnace is set with stepped calcination (in sequence: calcination at 385°C for 20 min, calcination at 400°C for 30 min, calcination at 450°C for 30 min, and calcination at 480°C for 20 min) to form a surface zinc-aluminum alloy. This step is to clean the residual chloride ions in the aluminum foil and generate a zinc-aluminum protective film.

[0158] S4. After washing the etched aluminum foil obtained from S3 with pure water, dry it in a 100℃ oven and remove it to obtain an electrochemical current collector with a protective film.

[0159] Example 6

[0160] This embodiment provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0161] S1. Take aluminum foil of grade 1090 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 30μm, porosity of the etched layer of 50%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 15% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 40s and the solution temperature is 52℃.

[0162] S2. The electrochemical current collector obtained after S1 treatment is placed in a 1% zinc sulfate solution (solvent is pure water) and soaked at 52°C for 40 seconds. After rinsing with pure water, the sample is placed in a tube furnace under argon atmosphere protection. The tube furnace is set with stepped calcination (in sequence: calcination at 385°C for 20 min, calcination at 400°C for 30 min, calcination at 450°C for 30 min, and calcination at 480°C for 20 min) to form a surface zinc-aluminum alloy. This step is to clean the residual chloride ions in the aluminum foil and generate a zinc-aluminum protective film.

[0163] S3. The electrochemical current collector obtained after S2 treatment is placed in a 1% ammonium dihydrogen phosphate solution (solvent is pure water). This step further cleans the residual impurities in the aluminum foil and forms a protective film. The treatment time is 40s and the solution temperature is 60℃.

[0164] S4. After washing the etched aluminum foil obtained from S3 with pure water, dry it in a 100℃ oven and remove it to obtain an electrochemical current collector with a composite protective film.

[0165] Example 7

[0166] This embodiment provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0167] S1. Take aluminum foil of grade 1090 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 50%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 15% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 30s and the solution temperature is 48℃.

[0168] S2. The electrochemical current collector obtained after S1 treatment is placed in a 1.5% zinc sulfate solution (solvent is pure water) and soaked at 48°C for 30 seconds. After rinsing with pure water, the sample is placed in a tube furnace under argon atmosphere protection. The tube furnace is set with stepped calcination (in sequence: calcination at 385°C for 20 min, calcination at 400°C for 30 min, calcination at 450°C for 30 min, and calcination at 480°C for 20 min) to form a surface zinc-aluminum alloy. This step is to clean the residual chloride ions in the aluminum foil and generate a zinc-aluminum protective film.

[0169] S3. The electrochemical current collector obtained after S2 treatment is placed in a 1.5% ammonium dihydrogen phosphate solution (solvent is pure water). This step further cleans the residual impurities in the aluminum foil and forms a protective film. The treatment time is 30s and the solution temperature is 48℃.

[0170] S4. After washing the etched aluminum foil obtained from S3 with pure water, dry it in a 100℃ oven and remove it to obtain an electrochemical current collector with a composite protective film.

[0171] Example 8

[0172] This embodiment provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0173] S1. Using aluminum foil with a purity of 99.99%, an electrochemical current collector with micro-nano pores on the surface is obtained by electrochemical etching with a chlorine-containing solution (thickness of 20μm, porosity of the etched layer of 50%, and pore size of 0.1-2μm). After the current collector is washed with pure water, it is placed in a 15% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 30s and the solution temperature is 52℃.

[0174] S2. The electrochemical current collector obtained after S1 is placed in a 1.5% zinc sulfate solution (solvent is pure water) and soaked at 52°C for 30 seconds. After rinsing with pure water, the sample is placed in a tube furnace under argon atmosphere protection. The tube furnace is set with stepped calcination (in sequence: calcination at 385°C for 20 min, calcination at 400°C for 30 min, calcination at 450°C for 30 min, and calcination at 480°C for 20 min) to form a surface zinc-aluminum alloy. This step is to clean the residual chloride ions in the aluminum foil and generate a zinc-aluminum protective film.

[0175] S3. After washing the etched aluminum foil obtained from S2 with pure water, dry it in a 100℃ oven and remove it to obtain an electrochemical current collector with a protective film.

[0176] Example 9

[0177] This embodiment provides a cleaning method for an electrochemical current collector. The only difference from Embodiment 1 is that the oxalic acid solution in S1 is replaced with an lactic acid solution of equal mass percentage; and the zinc sulfate solution in S2 is replaced with a zinc oxalate solution; the other steps are completely the same as in Embodiment 1.

[0178] Example 10

[0179] This embodiment provides a cleaning method for an electrochemical current collector. The only difference from Embodiment 2 is that the oxalic acid solution in S1 is replaced with an equal mass percentage of citric acid solution; the ammonium adipate solution in S2 is replaced with ammonium sebacate solution; and the zinc sulfate solution in S3 is replaced with zinc tartrate solution. All other steps are completely consistent with Embodiment 2.

[0180] Example 11

[0181] This embodiment provides a cleaning method for an electrochemical current collector. The only difference from Embodiment 6 is that the oxalic acid solution in S1 is replaced with an tartaric acid solution of equal mass percentage; the zinc sulfate solution in S2 is replaced with a zinc acetate solution; and the ammonium dihydrogen phosphate solution in S3 is replaced with a diammonium hydrogen phosphate solution. The other steps are completely the same as in Embodiment 6.

[0182] Example 12

[0183] This embodiment provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0184] S1. Take aluminum foil of grade 1070 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 30%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 9% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 60s and the solution temperature is 52℃.

[0185] S2. The electrochemical current collector obtained after S1 is placed in a 7% ammonium adipate solution (solvent is pure water) to clean the residual chloride ions in the electrochemical current collector. The treatment time is 120s and the solution temperature is 65℃.

[0186] S3. The electrochemical current collector obtained after S2 treatment is placed in a 0.3% zinc sulfate solution (solvent is pure water) and immersed at 45°C for 60 seconds. After rinsing with pure water, the sample is placed in a tube furnace under argon atmosphere protection. The tube furnace is set with stepped calcination (sequentially including: calcination at 385°C for 20 min, calcination at 400°C for 30 min, calcination at 450°C for 30 min, and calcination at 480°C for 20 min) to form a surface zinc-aluminum alloy. This step is to clean the residual chloride ions in the aluminum foil and generate a zinc-aluminum protective film.

[0187] S4. After washing the etched aluminum foil obtained from S3 with pure water, dry it in a 100℃ oven and remove it to obtain an electrochemical current collector with a protective film.

[0188] Example 13

[0189] This embodiment provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0190] S1. Take aluminum foil of grade 1090 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 50%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 15% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 40s and the solution temperature is 52℃.

[0191] S2. The electrochemical current collector obtained after S1 treatment is placed in a mixed solution of 1% zinc sulfate and 1% ammonium dihydrogen phosphate (solvent is pure water) and soaked at 60°C for 80 seconds. After being cleaned with pure water, the sample is placed in a tube furnace under argon atmosphere protection and calcined at 420°C for 2 hours.

[0192] S3. After washing the etched aluminum foil obtained from S2 with pure water, dry it in a 100℃ oven and remove it to obtain an electrochemical current collector with a composite protective film.

[0193] Comparative Example 1

[0194] This comparative example provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0195] S1. Take aluminum foil of grade 1070 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 30%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 9% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 60s and the solution temperature is 52℃.

[0196] S2. After washing the etched aluminum foil obtained from S1 with pure water, place it in a 100℃ oven to dry and remove it.

[0197] Comparative Example 2

[0198] This comparative example provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0199] S1. Take aluminum foil of grade 1070 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 30μm, porosity of 30% and pore size of 0.1-2μm). After the current collector is washed with pure water, it is placed in a 9% sulfuric acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 60s and the solution temperature is 52℃.

[0200] S2. After washing the etched aluminum foil obtained from S1 with pure water, place it in a 100℃ oven to dry and remove it.

[0201] Comparative Example 3

[0202] This comparative example provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0203] S1. Take aluminum foil of grade 1090 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 50%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 9% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 60s and the solution temperature is 52℃.

[0204] S2. After washing the etched aluminum foil obtained from S1 with pure water, it is dried in a 100℃ oven and removed to obtain an electrochemical current collector with a protective film.

[0205] Comparative Example 4

[0206] This comparative example provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0207] S1. Take aluminum foil of grade 1090 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 50%, pore size of 0.1-2μm%). After the current collector is washed with pure water, it is placed in a 9% sulfuric acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 60s and the solution temperature is 52℃.

[0208] S2. After washing the etched aluminum foil obtained from S1 with pure water, place it in a 100℃ oven to dry and remove it.

[0209] Comparative Example 5

[0210] This comparative example provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0211] S1. Take aluminum foil of grade 1070 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 30%, pore size of 0.1~2μm). After the current collector is washed with pure water, it is placed in a 9% sulfuric acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 60s and the solution temperature is 52℃.

[0212] S2. The electrochemical current collector obtained after S1 is placed in a zinc sulfate solution with a mass percentage of 0.3% (solvent is pure water). This step is to clean the residual chloride ions in the aluminum foil and generate a zinc-aluminum protective film. The treatment time is 60s and the solution temperature is 45℃.

[0213] S3. After washing the etched aluminum foil obtained from S2 with pure water, place it in a 100℃ oven to dry and remove it.

[0214] Comparative Example 6

[0215] This comparative example provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0216] S1. Take aluminum foil of grade 1070 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 30%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 9% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 60s and the solution temperature is 52℃.

[0217] S2. The electrochemical current collector obtained after treatment S1 is placed in a 7% (w / w) ammonium adipate solution (solvent: pure water). A graphite electrode plate is installed in the tank. Reverse current is applied to clean residual chloride ions from the electrochemical current collector. The current density during this reverse current application is set to 10 mA / cm². 2 The voltage was set to 5V, the processing time to 60s, and the solution temperature to 65℃.

[0218] S3. After washing the etched aluminum foil obtained from S2 with pure water, place it in a 100℃ oven to dry and remove it.

[0219] Comparative Example 7

[0220] This comparative example provides a cleaning method for an electrochemical current collector, the cleaning method specifically including the following steps:

[0221] S1. Take aluminum foil of grade 1090 and electrochemically etch it with chlorine solution to obtain an electrochemical current collector with micro-nano pores on the surface (thickness of 20μm, porosity of the etched layer of 50%, pore size of 0.1~2μm). After the current collector is cleaned with pure water, it is placed in a 15% oxalic acid solution (solvent is pure water) to remove the aluminum powder electrochemically etched from the micro-nano pores. The processing time is 40s and the solution temperature is 52℃.

[0222] S2. The electrochemical current collector obtained after S1 is placed in a 1% ammonium dihydrogen phosphate solution (solvent is pure water). This step further cleans the residual impurities in the aluminum foil and forms a protective film. The treatment time is 40s and the solution temperature is 60℃.

[0223] S3. After washing the etched aluminum foil obtained from S2 with pure water, place it in a 100℃ oven to dry and remove it.

[0224] Test case

[0225] Test samples: electrochemical current collectors obtained by the method provided in Examples 1-13, and electrochemical current collectors obtained by the method provided in Comparative Examples 1-7.

[0226] Test method:

[0227] (1) Chloride ion test: Cut 10cm × 10cm samples from each of the above samples, chop them into small pieces, and place them into 100mL volumetric flasks. Add 60mL of pure water to each volumetric flask, place the flasks in boiling water at 100℃ for 60min, remove them, let them stand at room temperature, and then dilute to 100mL with pure water and shake well. Check that all indicators of the IC-900 ion chromatography meet the injection standards, and then inject the pretreated samples into the IC-900 for testing. Note that the injection port must be cleaned and the 0.22μm filter at the injection port must be replaced before each injection. After the test is completed, observe the baseline and read the data.

[0228] (2) Internal resistance test: The above samples are made into electrode sheets, and 10mm×25mm is used to make a 2.7V10F supercapacitor. The internal resistance is measured in accordance with 6.4.1.4 of GB / T34870.1.

[0229] (3) 1000h life test: The above samples were made into electrode sheets, and 110mm×25mm was used to make a 2.7V10F supercapacitor. The supercapacitor was placed in a high temperature test chamber with a set temperature of 85±2℃ for 1000h. Then it was placed at room temperature for 24h and the internal resistance was measured in accordance with 6.4.1.4 of GB / T34870.1.

[0230] The specific test results are shown in Table 1 below:

[0231] Table 1

[0232]

[0233] As shown in Table 1, the chloride ion content of the electrochemical current collector after cleaning by the cleaning method described in this invention can be reduced to 1.0213 mg / m³. 2 The preferred method can reduce the dosage to 0.5000 mg / m². 2 The internal resistance of the supercapacitor prepared by the electrochemical current collector obtained by the present invention is controlled to be less than 25mΩ, and preferably less than 23mΩ; the internal resistance during the 1000h high-temperature lifespan is less than 50mΩ, and preferably less than 45mΩ.

[0234] As can be seen from the post-treatment processes of electrochemical current collectors in Comparative Examples 2 and 4, when sulfuric acid solution is used for post-treatment, the electrochemical current collector reacts violently with the solution, releasing a large number of bubbles, especially the electrochemical current collector with grade 1070. However, when oxalic acid solution is used to clean the residual aluminum powder in the electrochemical current collector, the reaction is relatively mild, and the amount of bubbles released is large but not violent.

[0235] Meanwhile, as shown in Table 1, the etched aluminum foil with uniform nanopores obtained through electrochemical etching exhibits significant advantages with the optimized post-processing method. All performance parameters are significantly improved, and when applied to batteries, it can significantly enhance the adhesion of battery electrodes and reduce the internal resistance of supercapacitors, thus extending their lifespan. This method primarily involves controlling the current and voltage during reverse electrolysis to coordinate their interaction and remove crystal defects in the etched foil material, including vacancies, interstitial atoms, impurities, solute atoms, and dislocations. Crystal defects have higher energy than other locations, making them more susceptible to electrolyte reactions. This damages the SEM film at these locations, increasing leakage current, raising internal resistance, and lowering voltage, thus affecting overall battery performance and lifespan. The reverse electrolysis method effectively removes crystal defects and impurities, reducing internal resistance. Furthermore, the zinc-aluminum alloy formed by zinc and aluminum reduces the negative pressure of chloride ions on aluminum in solution, better cleaning chloride ions from the electrochemically etched aluminum foil. The zinc-aluminum alloy also helps prevent corrosion of the electrochemical aluminum foil current collector. This invention can reduce the bonding resistance between electrochemically etched aluminum foil and coating, and can improve the lifespan of supercapacitors.

[0236] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cleaning method for an electrochemical current collector, characterized in that, The cleaning method includes: The electrochemically etched electrochemical current collector is placed in a weak acid solution and acid-washed to obtain the acid-washed electrochemical current collector. The acid-washed electrochemical current collector is placed in a zinc salt solution for treatment to form a zinc-aluminum alloy film, thus obtaining an electrochemical current collector with a protective film.

2. The cleaning method for the electrochemical current collector according to claim 1, characterized in that, The electrochemically etched electrochemical current collector is an electrochemically etched aluminum foil current collector; and the surface of the electrochemically etched aluminum foil current collector has micro- and nano-pores. Among them, aluminum powder remaining after electrochemical etching exists in the micro-nano pores; and chloride ions remaining after electrochemical etching exist on the electrochemically etched aluminum foil current collector. Preferably, the thickness of the electrochemically etched aluminum foil current collector is 15–30 μm; Preferably, the porosity of the electrochemically etched aluminum foil current collector is 30-60%, and the pore size of the electrochemically etched aluminum foil current collector is 0.1-2.0 μm.

3. The cleaning method for the electrochemical current collector according to claim 1, characterized in that, The weak acid includes any one or a combination of at least two of oxalic acid, acetic acid, lactic acid, boric acid, succinic acid, citric acid or tartaric acid, preferably oxalic acid; Preferably, the mass percentage of the weak acid in the weak acid solution is 5-20%; Preferably, the pickling temperature is 40–60°C; Preferably, the pickling time is 20 to 80 seconds.

4. The cleaning method for the electrochemical current collector according to claim 1, characterized in that, The process specifically includes the following steps: The acid-washed electrochemical current collector is immersed in a zinc salt solution, washed, and then calcined to form a zinc-aluminum alloy film. Preferably, the zinc salt in the zinc salt solution includes any one or a combination of at least two of zinc sulfate, zinc oxalate, zinc citrate, zinc tartrate, or zinc acetate, preferably zinc sulfate; Preferably, the zinc salt solution contains 0.1% to 2% zinc salt by mass. Preferably, the soaking temperature is 30–60°C; the soaking time is 20–120 seconds. Preferably, the calcination is carried out in the presence of a protective gas; Preferably, the protective gas comprises nitrogen and / or argon; Preferably, the calcination temperature is 300–500°C, and the calcination time is 60–180 min; Preferably, the calcination is carried out using a gradient heating segmented calcination procedure; wherein the gradient heating segmented calcination procedure includes, in sequence: calcination at 380-390℃ for 10-30 min, calcination at 390-410℃ for 20-40 min, calcination at 440-460℃ for 20-40 min, and calcination at 470-490℃ for 10-30 min.

5. The cleaning method for the electrochemical current collector according to claim 1, characterized in that, The pickling process also includes the following steps: The acid-washed electrochemical current collector is placed in a weak alkaline solution and reverse-current is applied to obtain an alkaline-washed electrochemical current collector.

6. The cleaning method for the electrochemical current collector according to claim 5, characterized in that, The weak base includes any one or a combination of at least two of ammonium adipate, ammonium glutarate, ammonium sebacate, ammonium formate, or ammonium acetate, preferably ammonium adipate; Preferably, the reverse voltage is 1–20V and the current density is 1–50mA / cm². 2 ; Preferably, the reverse power-on processing time is 20–120 seconds; Preferably, the electrode plate used for reverse power application includes any one of stainless steel electrode plate, titanium electrode plate, or graphite electrode plate.

7. The cleaning method for the electrochemical current collector according to claim 1, characterized in that, The process further includes the following steps: An electrochemical current collector with a protective film is placed in a phosphate solution and then cleaned to form a protective film with phosphate ions, thus obtaining an electrochemical current collector with a composite protective film.

8. The cleaning method for the electrochemical current collector according to claim 7, characterized in that, The phosphate includes any one or a combination of at least two of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, or ammonium phosphate, preferably ammonium dihydrogen phosphate; Preferably, the phosphate solution contains 0.1% to 2% phosphate by mass. Preferably, the temperature of the post-treatment cleaning is 48–60°C; Preferably, the post-treatment cleaning time is 30-40 seconds.

9. An electrochemical current collector, characterized in that, The electrochemical current collector has a protective film; and the electrochemical current collector is obtained by the cleaning method for electrochemical current collectors as described in any one of claims 1 to 8.

10. The application of the electrochemical current collector according to claim 9 in the preparation of supercapacitors or lithium batteries.

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