CN107331868A - A kind of coating fluid, its application method and battery pole piece - Google Patents

Abstract

The invention provides a coating solution comprising A component and B component; A component comprises 5-40 parts by weight of the first polymer, 5-35 parts by weight of the second polymer, 0.1-5 parts by weight of the first Joint agent and 10 to 70 parts by weight of water; the first polymer is one or more of polyurethane and its derivatives, polyvinyl alcohol and its derivatives, phenolic resin, polyacrylamide and its derivatives; the second The two polymers are one or more of polyacrylic acid and its derivatives, polysaccharide polymers, polyvinyl alcohol and its derivatives, polyester, polyurethane and its derivatives; the B component includes 0.01 to 5 weight Parts of the second crosslinking agent and 10-90 parts by weight of water. Compared with the prior art, the present invention adopts two-component coating solution, adopts two-step cross-linking method to form a cross-linking and mutual transmission network inside the coating, so that the obtained coating has stronger adhesion to metal , improves the stability of the coating, and also has better water resistance and solvent resistance.

Description

A kind of coating liquid, its using method and battery pole piece

technical field

The invention belongs to the technical field of electrochemistry, and in particular relates to a coating solution, a method for using the same and a battery pole piece.

Background technique

In conventional electrochemical devices, the manufacturing process of battery pole pieces is to directly coat the active material slurry on the surface of the metal collector, and after drying, the active material is fixed on the surface of the collector through a binder. However, such a structural design has the following two defects: 1) The contact area between the rigid metal current collector and the active material particles is limited, and the interface resistance is large, which causes an increase in the internal resistance of the battery, which affects the performance of the electrochemical device. Negative impact; 2) The bonding strength of the binder is limited. During the continuous charging and discharging process, it is easy to cause the expansion and separation between the active material and the current collector, resulting in a further increase in the internal resistance of the battery, which makes the cycle life and the safety of the battery Performance suffers. Therefore, reducing the interfacial resistance between the current collector and the active material and improving the bonding strength between the two are important means to improve the performance of lithium secondary batteries. The introduction of a conductive coating on the surface of the metal collector can effectively improve the adhesion between the active material and the metal collector, reduce the interface impedance, and reduce the corrosion of the electrolyte on the metal collector, which is beneficial to prolong the service life of the electrochemical device. and improve its security.

Chinese patent application number 201180042480.2 discloses a coating solution for metal collectors, the coating solution contains conductive materials, polysaccharides and polysaccharide derivatives, and organic acids and their derivatives. After the derivative is coated on the metal surface, a cross-linked coating is formed through the condensation reaction between the polysaccharide and the organic acid, thereby realizing the fixing of the conductive coating on the metal surface.

The Chinese patent application number CN00814654.3 discloses a coating machine for coating metal surfaces. The coating agent contains conductive materials, adhesives curable at high temperatures and other auxiliary substances. It utilizes polyurethane/acrylic acid The crosslinking of mixtures of ester copolymers, polyurethane/polycarbonate dispersions, polyurethane/polyester dispersions and acrylate copolymer dispersions at elevated temperatures achieves curing of conductive coatings.

However, both of the above two methods adopt a one-step method to realize the curing of the conductive coating. The curing efficiency is low, the stability of the conductive coating is poor, and the interaction with the collector is also weak. These shortcomings will affect the modification. On the other hand, the electrical conductivity of the collector also affects its long-term stability.

Contents of the invention

In view of this, the technical problem to be solved by the present invention is to provide a coating solution, a method for using the same and a battery pole piece, and the coating solution improves the stability of the conductive coating.

The invention provides a coating liquid, including A component and B component;

The A component includes: 5-40 parts by weight of the first polymer, 5-35 parts by weight of the second polymer, 0.1-5 parts by weight of the first crosslinking agent and 10-70 parts by weight of water; The first polymer is selected from one or more of polyurethane and its derivatives, polyvinyl alcohol and its derivatives, phenolic resin, polyacrylamide and its derivatives; the second polymer is selected from polyacrylic acid and One or more of its derivatives, polysaccharide polymers, polyvinyl alcohol and its derivatives, polyester, polyurethane and its derivatives;

The B component includes: 0.01-5 parts by weight of the second crosslinking agent and 10-90 parts by weight of water.

Preferably, the mass fraction of the total amount of the first polymer, the second polymer and the first crosslinking agent in the A component is less than or equal to 40%.

Preferably, the first crosslinking agent is selected from aldehyde crosslinking agents and/or acid anhydride crosslinking agents.

Preferably, the second crosslinking agent is selected from one or more of aldehyde crosslinking agents, metal polynuclear hydroxy bridge ions and phenolic crosslinking agents.

Preferably, the aldehyde crosslinking agent is selected from one or more of formaldehyde, glyoxal, glutaraldehyde and urea-formaldehyde; the polynuclear hydroxy bridge ion of the metal is selected from the polynuclear hydroxy bridge ion of zirconium and /or polynuclear hydroxy bridging ions of chromium; the phenolic crosslinking agent is selected from phenol and/or resorcinol.

Preferably, the component A further includes 20-50 parts by weight of conductive material.

The present invention also provides a method for using the coating liquid, comprising the following steps:

S1) Coating component A on the metal surface to obtain the coated metal;

S2) immersing the coated metal in component B, then bathing in water, and drying to obtain a metal with a coating attached to the surface;

The A component includes: 5-40 parts by weight of the first polymer, 5-35 parts by weight of the second polymer, 0.1-5 parts by weight of the first crosslinking agent and 10-70 parts by weight of water; The first polymer is selected from one or more of polyurethane and its derivatives, polyvinyl alcohol and its derivatives, phenolic resin, polyacrylamide and its derivatives; the second polymer is selected from polyacrylic acid and One or more of its derivatives, polysaccharide polymers, polyvinyl alcohol and its derivatives, polyester, polyurethane and its derivatives;

The B component includes: 0.01-5 parts by weight of the second crosslinking agent and 10-90 parts by weight of water.

Preferably, the temperature of component B in the step S2) is 100°C-150°C; the drying temperature is 50°C-150°C.

The present invention also provides a battery pole piece, comprising a current collector and an active material layer attached to the surface of the current collector; the active material layer is formed by the above-mentioned coating solution.

The present invention also provides an electrochemical element, including the above-mentioned electrode sheet.

The invention provides a coating solution comprising A component and B component; the A component comprises: 5-40 parts by weight of the first polymer, 5-35 parts by weight of the second polymer, 0.1-5 parts by weight Parts by weight of the first crosslinking agent and 10-70 parts by weight of water; the first polymer is selected from polyurethane and its derivatives, polyvinyl alcohol and its derivatives, phenolic resin, polyacrylamide and its derivatives One or more of; the second polymer is selected from one or more of polyacrylic acid and its derivatives, polysaccharide polymers, polyvinyl alcohol and its derivatives, polyester, polyurethane and its derivatives ; The B component includes: 0.01-5 parts by weight of the second crosslinking agent and 10-90 parts by weight of water. Compared with the prior art, the present invention adopts two-component coating solution, adopts two-step cross-linking method to form a cross-linking and mutual transmission network inside the coating, so that the obtained coating has stronger adhesion to metal , improve the stability of the coating, and the coating has better water resistance and solvent resistance with the aid of the cross-linked intertransmission network.

Description of drawings

Fig. 1 is the cross-linking internal resistance curve of the aluminum foil with coating and common aluminum foil obtained in Example 1 of the present invention;

Fig. 2 is a rate charging curve of coated aluminum foil and ordinary aluminum foil obtained in Example 1 of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The invention provides a coating solution, which includes A component and B component; the A component includes: 5-40 parts by weight of the first polymer, 5-35 parts by weight of the second polymer, 0.1- 5 parts by weight of the first crosslinking agent and 10-70 parts by weight of water; the first polymer is selected from polyurethane and its derivatives, polyvinyl alcohol and its derivatives, phenolic resin, polyacrylamide and its derivatives One or more of them; the second polymer is selected from one or more of polyacrylic acid and its derivatives, polysaccharide polymers, polyvinyl alcohol and its derivatives, polyester, polyurethane and its derivatives species; the B component includes: 0.01-5 parts by weight of the second crosslinking agent and 10-90 parts by weight of water.

Among them, the present invention has no special limitation on the sources of all raw materials, which can be commercially available.

According to the present invention, the content of the first polymer in the A component is preferably 4 to 35 parts by weight; in some embodiments provided by the present invention, the content of the first polymer is preferably 5 parts by weight; in this invention In some embodiments provided by the invention, the content of the first polymer is preferably 28 parts by weight; in other embodiments provided by the invention, the content of the first polymer is preferably 35 parts by weight; A polymer is one or more of polyurethane and its derivatives, polyvinyl alcohol and its derivatives, phenolic resin, polyacrylamide and its derivatives, preferably polyurethane and its derivatives.

The content of the second polymer is preferably 5-30 parts by weight, more preferably 8-25 parts by weight; in some embodiments provided by the present invention, the content of the second polymer is preferably 25 parts by weight; In some embodiments provided by the present invention, the content of the second polymer is preferably 10 parts by weight; in other embodiments provided by the present invention, the content of the second polymer is preferably 8 parts by weight; the The second polymer is one or more of polyacrylic acid and derivatives thereof, polysaccharide polymers, polyvinyl alcohol and derivatives thereof, polyester, polyurethane and derivatives thereof, preferably polysaccharide polymers, more Chitin is preferred.

The content of the first crosslinking agent is preferably 0.5 to 5 parts by weight, more preferably 1 to 5 parts by weight, more preferably 2 to 4 parts by weight, most preferably 2 to 3 parts by weight; the first crosslinking agent The agent can be a cross-linking agent well known to those skilled in the art, and there is no special limitation. In the present invention, it is preferably an aldehyde cross-linking agent and/or an acid anhydride cross-linking agent; Aldehyde cross-linking agents well-known to personnel can be used without special limitations. In the present invention, one or more of formaldehyde, glyoxal, glutaraldehyde and urea-formaldehyde are preferred; the acid anhydride cross-linking agent is based on An acid anhydride crosslinking agent well known to those skilled in the art can be used without any special limitation, and phthalic anhydride is preferred in the present invention.

According to the present invention, the total mass fraction of the first polymer, the second polymer and the first crosslinking agent in component A is preferably less than or equal to 40%, more preferably 10% to 40%, and more preferably 20% ~40%, most preferably 20%~30%; in some embodiments provided by the present invention, the total mass fraction of the first polymer, the second polymer and the first crosslinking agent in component A is preferably 20%; in some embodiments provided by the invention, the total mass fraction of the first polymer, the second polymer and the first crosslinking agent in component A is preferably 25.5%; in the invention provided In some other embodiments, the total mass fraction of the first polymer, the second polymer and the first crosslinking agent in component A is preferably 30.4%.

The content of water in the component A is preferably 20-70 parts by weight, more preferably 40-70 parts by weight, and even more preferably 50-70 parts by weight.

According to the present invention, the A component preferably further includes 20 to 50 parts by weight of conductive materials, more preferably 30 to 50 parts by weight of conductive materials, more preferably 40 to 50 parts by weight of conductive materials, most preferably It also includes 45 to 50 parts by weight of conductive material; the conductive material is a conductive material well known to those skilled in the art, and there is no special limitation. In the present invention, it is preferably conductive carbonaceous material and/or metal powder; The conductive carbonaceous material can be a conductive carbonaceous material well known to those skilled in the art, and there is no special limitation. In the present invention, it is preferably acetylene black, Ketjen black, carbon fibrils, carbon nanotubes, carbon nanofibers and graphite. One or more; the metal powder is preferably one or more of gold, silver, copper, nickel and aluminum powder.

Preferably, the A component further includes 0.1 to 10 parts by weight of auxiliary agents, more preferably 1 to 10 parts by weight of auxiliary agents, more preferably 1 to 8 parts by weight of auxiliary agents, and most preferably 2 to 10 parts by weight. The auxiliary agent of 5 parts by weight; Said auxiliary agent is the auxiliary agent well known to those skilled in the art, and there is no special limitation, preferably in the present invention, a kind of in organic solvent, thickener, viscosifier and flow agent or more; the organic solvent is an organic solvent well known to those skilled in the art, and there is no special limitation. In the present invention, it is preferably an alcohol solvent and/or N-methylpyrrolidone, more preferably a C1～C4 alcohol Solvent and/or N-methylpyrrolidone; The thickener is a thickener well known to those skilled in the art, and there is no special limitation, preferably sodium carboxymethyl cellulose in the present invention; The thickener The agent can be a tackifier well known to those skilled in the art, without any special limitation, preferably polyacrylate in the present invention; the flow agent can be a flow agent well known to those skilled in the art, without any special limitation In the present invention, it is preferably silane flow agent and/or siloxane flow set, more preferably trimethoxymethylsilane, isobutyltrimethoxysilane, n-octyltriethoxysilane, 3-amino Propyltrimethoxysilane, 2-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane , one or more of 3-glycidoxypropyltrimethoxysilane and β(3,4-epoxycyclohexyl)ethyltriethoxysilane.

The B component includes 0.01 to 5 parts by weight of the second crosslinking agent and 10 to 90 parts by weight of water; wherein, the content of the second crosslinking agent is preferably 1 to 5 parts by weight, more preferably 2 to 5 parts by weight. 5 parts by weight; in some embodiments provided by the invention, the content of the second crosslinking agent in the B component is preferably 4 parts by weight; in some embodiments provided by the invention, the second crosslinking agent in the B component The content of the second crosslinking agent is preferably 2 parts by weight; in other embodiments provided by the present invention, the content of the second crosslinking agent in the B component is preferably 5 parts by weight; the second crosslinking agent is The cross-linking agent well known to those skilled in the art can be used without any special limitation. In the present invention, it is preferably one or more of aldehyde cross-linking agent, metal polynuclear hydroxy bridge ion and phenolic cross-linking agent; The aldehyde crosslinking agent is preferably one or more of formaldehyde, glyoxal, glutaraldehyde and urea-formaldehyde; the polynuclear hydroxy bridge ion of the metal is preferably the polynuclear hydroxy bridge ion of zirconium and/or chromium The polynuclear hydroxy bridging ion; the phenolic crosslinking agent is preferably phenol and/or resorcinol; the content of the water is preferably 10 to 60 parts by weight, more preferably 20 to 50 parts by weight, and more preferably 30-40 parts by weight.

The present invention adopts two-component coating solution, adopts two-step cross-linking method to form a cross-linking and mutual transmission network inside the coating, so that the obtained coating has a stronger adhesion to the metal and improves the stability of the coating. Sex, and the coating has better water resistance and solvent resistance with the help of cross-linked inter-transmission network.

The present invention also provides a method for using the above-mentioned coating liquid, comprising the following steps:

S1) Coating component A on the metal surface to obtain the coated metal;

S2) immersing the coated metal in component B, then bathing in water, and drying to obtain a metal with a coating attached to the surface;

The A component includes: 5-40 parts by weight of the first polymer, 5-35 parts by weight of the second polymer, 0.1-5 parts by weight of the first crosslinking agent and 10-70 parts by weight of water; The first polymer is selected from one or more of polyurethane and its derivatives, polyvinyl alcohol and its derivatives, phenolic resin, polyacrylamide and its derivatives; the second polymer is selected from polyacrylic acid and One or more of its derivatives, polysaccharide polymers, polyvinyl alcohol and its derivatives, polyester, polyurethane and its derivatives;

The B component includes: 0.01-5 parts by weight of the second crosslinking agent and 10-90 parts by weight of water.

Wherein, the A component and the B component are the same as above, and will not be repeated here.

According to the present invention, it is preferable to pretreat the metal first; the pretreatment method of the metal can be a method well known to those skilled in the art, and there is no special limitation. In the present invention, it is preferred to use a low-concentration acid solution or alkaline solution Washing, and then rinsing with water or acetone; the concentration of the acid solution or alkali solution is preferably 1% to 10%, more preferably 2% to 8%, more preferably 3% to 6%, most preferably 5% %.

Then apply component A to the pretreated metal surface to obtain the coated metal; the coating method is a method well known to those skilled in the art, and there is no special limitation. It is preferably used in the present invention Roller traction, coating the coating solution on the pretreated metal surface, more preferably using gravure printing to coat the coating solution on the pretreated metal surface, and using a gravure anilox roller to control the thickness of the coating; The thickness of the coated metal coating is preferably 20 nm to 5 μm, more preferably 50 nm to 3 μm, more preferably 100 nm to 2 μm, and more preferably 200 nm to 500 nm.

Immerse the coated metal in component B; the temperature of component B is preferably 100°C to 150°C, more preferably 110°C to 140°C, more preferably 120°C to 140°C, most preferably 130°C to 135°C; the dipping time is preferably 2 to 60s, more preferably 10 to 50s, and more preferably 20 to 30s; in the present invention, the coated metal is preferably pulled into the B component via a roller Medium; the pulling speed is preferably 2 to 150m/min, more preferably 5 to 150m/min, more preferably 50 to 150m/min, more preferably 50 to 100m/min, and more preferably 80 to 100m/min .

After dipping, carry out water bath; The time of described water bath is preferably 2～60s, more preferably is 30～60s; In the present invention, preferably enters water bath through roller traction; The speed of described traction is preferably 2～150m/min, more preferably Preferably it is 5-150 m/min, more preferably 50-150 m/min, still more preferably 50-100 m/min, still more preferably 80-100 m/min. During this process a crosslinking reaction of the first polymer takes place.

Drying after a water bath; the drying temperature is preferably 50°C to 150°C, more preferably 80°C to 150°C, more preferably 100°C to 150°C, most preferably 120°C to 140°C; the drying time Preferably it is 10 to 180s. During this process, the aqueous solvent can be removed while crosslinking of the first polymer with the second polymer occurs to form a crosslinked polymeric network.

The coating solution and coating method can be used to modify the current collector to prepare battery pole pieces, and can also be used to modify the surface of metal thin film products, such as anti-corrosion of metal devices in the marine field.

The present invention adopts a two-step method to realize the curing of the coating, in which a part of the components are cross-linked and cured in the first step, and then the moisture is removed through the subsequent heating process, and the coating is further cross-linked to form a cross-linked mutual transmission network. The two-step cross-linking method is used to form a cross-linking and mutual transmission network inside the coating, so that the adhesion between the obtained coating and the metal is stronger, the stability of the coating is improved, and the cross-linking and mutual transmission is also used. The network makes the coating have better water resistance and solvent resistance.

The present invention also provides a battery pole piece, comprising a current collector and an active material layer attached to the surface of the current collector; the active material layer is formed from the above coating solution; the active material layer can be attached to the current collector One or both sides, there are no special restrictions.

The battery pole piece provided by the invention has high electronic conductivity, which is an important basis for ensuring its good use in electrochemical devices.

The present invention also provides an electrochemical element, comprising the above-mentioned battery pole piece.

The present invention also provides a power supply system, comprising the above-mentioned electrochemical element.

In order to further illustrate the present invention, a coating solution provided by the present invention, its use method and battery pole piece are described in detail below in conjunction with the examples.

The reagents used in the following examples are all commercially available.

Example 1

1.1 Preparation of coating solution:

Add 2 parts by weight of sodium carboxymethylcellulose to 60 parts by weight of solvent water and mix evenly, then add 5 parts by weight of the first polymer polyacrylamide, 25 parts by weight of the second polymer chitin, 2 parts by weight The second crosslinking agent phthalic anhydride is added to the above solution and mixed uniformly, and finally 45 parts by weight of conductive nano-graphite are added for high-speed dispersion and mixing to obtain component A;

4 parts by weight of the first crosslinking agent glyoxal and 30 parts by weight of solvent water were mixed to obtain component B.

1.2 Pretreatment of the metal film: the aluminum foil is first cleaned with a 5wt% concentration of hydrochloric acid solution, then rinsed with solvent deionized water, and then dried at a temperature of 150°C to remove impurities on the surface of the aluminum foil and make the surface of the aluminum foil form Uniform textured layer.

1.3 Use the roller to pull the aluminum foil at a speed of 80 m/min, apply the coating solution evenly on the surface of the pretreated aluminum foil by gravure printing, and use the gravure anilox roller to control the coating thickness, and the coating thickness is controlled at 1 μm .

1.4 Pull the coated aluminum foil into component B through a roller, the temperature is 130°C, the pulling speed is 100 m/min, and component B exits after 30 seconds.

1.5 After the coated aluminum foil comes out of component B, it directly enters the water bath. The traction speed was kept the same as before, and the water bath time was 1 minute.

1.6 After coming out of the water bath, enter the high-temperature drying zone. The temperature in the high-temperature drying zone is 140°C for 1 minute. After the polymerization is completed, the coated aluminum foil is dried and rolled up for use.

After the coating liquid was dried on the PET film, the electrical conductivity was measured by four probes to be 23.6 S/cm.

After soaking the coating obtained in Example 1 in N-methylpyrrolidone and electrolyte for 30 days, the coating did not fall off or bubble.

The coated aluminum foil obtained in Example 1 was assembled into a lithium-ion battery, and the performance of the battery was tested to obtain its AC internal resistance curve, as shown in Figure 1. From the results, it can be seen that compared with ordinary aluminum foil, the battery The internal resistance was reduced from 6.6mΩ to 3.7mΩ; the rate charging curve was obtained, as shown in Figure 2, the rate charging performance increased by more than 100% after 2.5C rate.

Example 2

2.1 Preparation of coating solution:

Add 5 parts by weight of sodium carboxymethyl cellulose to 70 parts by weight of solvent water and mix evenly, then add 28 parts by weight of the first polymer polyacrylamide, 10 parts by weight of the second polymer chitin, 3 parts by weight of The second crosslinking agent phthalic anhydride is added to the above solution and mixed uniformly, and finally 45 parts by weight of conductive carbon black and nano-graphite are added in a mass ratio of 2:1, and high-speed dispersion and mixing are carried out to obtain the A component;

2 parts by weight of the first crosslinking agent glyoxal and 30 parts by weight of solvent water were mixed to obtain component B.

2.2 Pretreatment of the metal film: the aluminum foil is first cleaned with a 5wt% concentration of hydrochloric acid solution, then rinsed with solvent deionized water, and then dried at a temperature of 150°C to remove impurities on the surface of the aluminum foil and make the surface of the aluminum foil form Uniform textured layer.

2.3 Use the roller to pull the aluminum foil at a speed of 150 m/min, apply the coating solution evenly on the surface of the pretreated aluminum foil by gravure printing, and use the gravure anilox roller to control the coating thickness, and the coating thickness is controlled at 500nm .

2.4 Pull the coated aluminum foil into component B through a roller, the temperature is 135°C, the pulling speed is 150 m/min, and component B exits after 10 seconds.

2.5 After the coated aluminum foil comes out of component B, it directly enters the water bath. The traction speed was kept the same as before, and the water bath time was 30 seconds.

2.6 After coming out of the water bath, enter the high-temperature drying zone. The temperature in the high-temperature drying zone is 120°C for 1 minute, and the coated aluminum foil after drying and polymerization is rolled up for use.

After the coating solution was dried on the PET film, the electrical conductivity was measured by four probes to be 12.5 S/cm.

After immersing the coated aluminum foil in Example 2 in N-methylpyrrolidone and electrolyte for 30 days, the coating did not fall off or bubble.

Example 3

3.1 Preparation of coating solution:

Add 3 parts by weight of carboxymethyl fiber into 60 parts by weight of solvent water and mix evenly, then add 35 parts by weight of the first polymer polyacrylamide, 8 parts by weight of the second polymer chitin, and 2 parts by weight of the second polymer The second crosslinking agent, phthalic anhydride, is added to the above solution and mixed uniformly, and finally 50 parts by weight of nano-graphite and carbon nanotubes with a mass ratio of 3:1 are added, and high-speed dispersion and mixing are carried out to obtain component A;

5 parts by weight of the first crosslinking agent glyoxal and 40 parts by weight of solvent water were mixed to obtain component B.

3.2 Pretreatment of the metal film: the copper foil is first cleaned with a 5wt% concentration of sulfuric acid solution, then rinsed with solvent deionized water, and then dried at a temperature of 120 ° C to remove impurities on the surface of the copper foil and make the copper A uniform textured layer is formed on the surface of the foil.

3.3 Use the roller to pull the copper foil at a speed of 60 m/min, apply the coating liquid evenly on the surface of the pretreated copper foil by gravure printing, and use the gravure anilox roller to control the coating thickness, and the coating thickness control At 1 μm (.

3.4 The coated copper foil is pulled into component B by a roller, the temperature is 130°C, the pulling speed is 30 m/min, and component B exits after 1 minute.

3.5 After the coated copper foil comes out of component B, it directly enters the water bath. The traction speed was kept the same as before, and the water bath time was 1 minute.

3.6 After coming out of the water bath, enter the high-temperature drying zone. The temperature in the high-temperature drying zone is 120 ° C, and the time is 2 minutes. After drying and polymerization, the coated copper foil is rolled up for use.

After the coating solution was dried on the PET film, the electrical conductivity was measured by four probes to be 36.2 S/cm.

After immersing the coated copper foil in N-methylpyrrolidone and electrolyte for 30 days, the coating did not fall off or bubble.

Claims (10)

1. A coating liquid, characterized in that, comprises A component and B component; The A component includes: 5-40 parts by weight of the first polymer, 5-35 parts by weight of the second polymer, 0.1-5 parts by weight of the first crosslinking agent and 10-70 parts by weight of water; The first polymer is selected from one or more of polyurethane and its derivatives, polyvinyl alcohol and its derivatives, phenolic resin, polyacrylamide and its derivatives; the second polymer is selected from polyacrylic acid and One or more of its derivatives, polysaccharide polymers, polyvinyl alcohol and its derivatives, polyester, polyurethane and its derivatives; The B component includes: 0.01-5 parts by weight of the second crosslinking agent and 10-90 parts by weight of water. 2. coating solution according to claim 1, is characterized in that, in described A component, the mass fraction of the total amount of the first polymer, the second polymer and the first crosslinking agent in A component is less than Equal to 40%. 3. The coating liquid according to claim 1, characterized in that, the first crosslinking agent is selected from aldehyde crosslinking agents and/or acid anhydride crosslinking agents. 4. coating solution according to claim 1, is characterized in that, described second linking agent is selected from one or more in aldehydes linking agent, the polynuclear hydroxyl bridging ion of metal and phenolic linking agent Various. 5. The coating liquid according to claim 4, characterized in that, the aldehyde crosslinking agent is selected from one or more of formaldehyde, glyoxal, glutaraldehyde and urea-formaldehyde; The hydroxy bridging ion is selected from polynuclear hydroxy bridging ions of zirconium and/or the polynuclear hydroxy bridging ion of chromium; the phenolic crosslinking agent is selected from phenol and/or resorcinol. 6. The coating solution according to claim 1, characterized in that, the component A further comprises 20-50 parts by weight of a conductive material. 7. A method for using a coating solution, comprising the following steps: S1) Coating component A on the metal surface to obtain the coated metal; S2) immersing the coated metal in component B, then bathing in water, and drying to obtain a metal with a coating attached to the surface; The A component includes: 5-40 parts by weight of the first polymer, 5-35 parts by weight of the second polymer, 0.1-5 parts by weight of the first crosslinking agent and 10-70 parts by weight of water; The first polymer is selected from one or more of polyurethane and its derivatives, polyvinyl alcohol and its derivatives, phenolic resin, polyacrylamide and its derivatives; the second polymer is selected from polyacrylic acid and One or more of its derivatives, polysaccharide polymers, polyvinyl alcohol and its derivatives, polyester, polyurethane and its derivatives; The B component includes: 0.01-5 parts by weight of the second crosslinking agent and 10-90 parts by weight of water. 8. The method according to claim 7, characterized in that, the temperature of component B in the step S2) is 100°C-150°C; the drying temperature is 50°C-150°C. 9. A battery pole piece, characterized in that it comprises a current collector and an active material layer attached to the surface of the current collector; the active material layer is formed by the coating solution according to any one of claims 1-6. 10. An electrochemical element, characterized in that it comprises the electrode sheet according to claim 9.