阅读说明：本技术 一种集流体导电涂层及其制备方法 (Current collector conductive coating and preparation method thereof ) 是由 不公告发明人 于 2019-10-15 设计创作，主要内容包括：本发明提供一种集流体导电涂层及其制备方法,涉及化学电源技术领域,所述集流体导电涂层包括高分子粘结剂、导电聚合物、导电粉体和交联组分,其中所述高分子粘结剂的重量百分比范围为0.1％-40％,所述导电聚合物的重量百分比范围为0.1％-40％,所述导电粉体的重量百分比范围为20％-80％,所述交联组分的重量百分比范围为为0.01％-10％。本发明提供的集流体导电涂层,通过加入导电聚合物与交联组分,在提高集流体导电涂层的导电能力的同时,能够提高集流体、集流体导电涂层以及电极活性物质三者之间的附着力,有效避免电极片在经过长期循环以后出现的阻抗增大、温度升高等问题。(The invention provides a current collector conductive coating and a preparation method thereof, and relates to the technical field of chemical power supplies, wherein the current collector conductive coating comprises a high-molecular binder, a conductive polymer, conductive powder and a crosslinking component, wherein the weight percentage range of the high-molecular binder is 0.1-40%, the weight percentage range of the conductive polymer is 0.1-40%, the weight percentage range of the conductive powder is 20-80%, and the weight percentage range of the crosslinking component is 0.01-10%. According to the current collector conductive coating provided by the invention, by adding the conductive polymer and the crosslinking component, the conductive capability of the current collector conductive coating is improved, the adhesive force among the current collector, the current collector conductive coating and the electrode active substance can be improved, and the problems of impedance increase, temperature rise and the like of an electrode plate after long-term circulation are effectively avoided.)

1. The current collector conductive coating is characterized by comprising a high-molecular binder, a conductive polymer, conductive powder and a crosslinking component, wherein the weight percentage range of the high-molecular binder is 0.1-40%, the weight percentage range of the conductive polymer is 0.1-40%, the weight percentage range of the conductive powder is 20-80%, and the weight percentage range of the crosslinking component is 0.01-10%.

2. The current collector conductive coating of claim 1, wherein the polymeric binder is selected from the group consisting of sodium carboxymethylcellulose, lithium carboxymethylcellulose, polyacrylic acid, polyamide, polyacrylamide, polyethylene glycol, polyacrylonitrile, polypropylene, polyethylene, polyvinyl alcohol, polyvinyl chloride, polyester, polyvinylidene fluoride, polytetrafluoroethylene, polyimide, epoxy resin, polyurethane, polyether ether ketone, polymethyl methacrylate, phenolic resin, modified acrylic acid, modified polyurethane, modified styrene-butadiene rubber, polymers containing hydroxyl or carboxyl functional groups, and sodium carboxymethylcellulose, lithium carboxymethylcellulose, polyacrylic acid, polyamide, polyacrylamide, polyethylene glycol, polyacrylonitrile, polypropylene, polyethylene, polyvinyl alcohol, polyvinyl chloride, polyester, polyvinylidene fluoride, polytetrafluoroethylene, polyimide, poly (vinyl alcohol), poly (vinyl chloride), poly (vinylidene fluoride), poly (tetrafluoroethylene), poly, At least one of epoxy resin, polyurethane, polyether ether ketone, polymethyl methacrylate, phenolic resin, modified acrylic acid, modified polyurethane, and a derivative, block or graft copolymer of modified styrene-butadiene rubber.

3. The current collector conductive coating of claim 1, wherein the conductive polymer is selected from the group consisting of polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene vinylene, polydiyne, and nitroxide organic radical polymerization, and at least one of polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene vinylene, polydiyne derivatives, block or graft copolymers, nitroxide organic radical polymerization.

4. The current collector conductive coating of claim 1, wherein the conductive powder is selected from at least one of carbon black, acetylene black, carbon nanotubes, carbon fibers, graphite, nanographite, graphene, fullerene, and conductive oxides.

5. The current collector conductive coating of claim 1, wherein the crosslinking component is selected from at least one of diacetone acrylamide monomer, or a cross-linked polyacrylic acid-diacetone acrylamide resin with adipic dihydrazide.

6. The current collector conductive coating of claim 1, wherein the current collector conductive coating has a thickness in a range from 0.05 μ ι η to 5 μ ι η.

7. The preparation method of the current collector conductive coating as claimed in any one of claims 1 to 6, wherein the method comprises the following steps:

s1: mixing a solvent, the high-molecular binder and the conductive powder, and performing premixing and dispersion to obtain a premixed solution;

s2: adding the conductive polymer and the crosslinking component into the premixed liquid, and mixing and dispersing to obtain conductive coating slurry;

s4: and coating the conductive coating slurry on the surface of a current collector to obtain the conductive coating of the current collector on the surface of the current collector.

8. The method of preparing a current collector conductive coating of claim 7, further comprising:

s3: and dispersing the conductive coating slurry in a dispersion system for 2-20 times.

9. The method for preparing a current collector conductive coating as claimed in claim 7, wherein the solvent is at least one selected from the group consisting of N-methyl pyrrolidone, deionized water, isopropanol, and absolute ethanol.

10. The method for preparing the current collector conductive coating as claimed in claim 7, wherein the time for performing the pre-mixing and dispersing in the steps S1 and S2 is 0.5-3 hours.

Technical Field

The invention relates to the technical field of chemical power supplies, in particular to a current collector conductive coating and a preparation method thereof.

Background

The electrode in the electrochemical system consists of a current collector and an electrode active substance coated on the current collector, wherein the current collector mainly plays a role in providing good electronic conduction capability for the electrochemical system.

At present, in order to increase the binding force and conductivity between the current collector and the electrode active material and avoid the corrosion of some materials in an electrochemical system to the current collector, the current collector is modified by coating a conductive coating on the current collector.

Disclosure of Invention

The invention solves the problem that the electron conduction capability of the conductive coating is limited due to the large use of the high-molecular binder.

In order to solve the above problems, the present invention provides a current collector conductive coating, which comprises a polymer binder, a conductive polymer, a conductive powder and a crosslinking component, wherein the weight percentage range of the polymer binder is 0.1% -40%, the weight percentage range of the conductive polymer is 0.1% -40%, the weight percentage range of the conductive powder is 20% -80%, and the weight percentage range of the crosslinking component is 0.01% -10%.

The conductive polymer has better adhesive property, and the dosage of the high molecular adhesive can be reduced by adding the conductive polymer; the conductive polymer has conductive performance besides the adhesive performance, and the conductive polymer is used for replacing part of high molecular adhesive, so that the bonding force between the conductive coating and the current collector is not influenced, the conductive capability of the conductive coating of the current collector is improved, the contact internal resistance of an electrochemical system is reduced, and the rate performance of the prepared electrochemical system is improved, namely the working performance and the cruising ability of the electrochemical system under high current are improved.

In addition, by adding the crosslinking component, the crosslinking component can be tightly combined with the current collector on one hand, and can be combined with the electrode active substance on the other hand, so that the adhesive force among the current collector, the current collector conductive coating and the electrode active substance can be improved, and the problems of resistance increase, temperature rise and the like of an electrochemical system caused by the falling of a motor layer and the swelling of the conductive coating after long-term circulation of the electrode plate are effectively avoided.

Optionally, the polymeric binder is selected from sodium carboxymethylcellulose, lithium carboxymethylcellulose, polyacrylic acid, polyamide, polyacrylamide, polyethylene glycol, polyacrylonitrile, polypropylene, polyethylene, polyvinyl alcohol, polyvinyl chloride, polyester, polyvinylidene fluoride, polytetrafluoroethylene, polyimide, epoxy resin, polyurethane, polyether ether ketone, polymethyl methacrylate, phenol resin, modified acrylic acid, modified polyurethane, modified styrene-butadiene rubber, polymers containing hydroxyl or carboxyl functional groups, and sodium carboxymethylcellulose, lithium carboxymethylcellulose, polyacrylic acid, polyamide, polyacrylamide, polyethylene glycol, polyacrylonitrile, polypropylene, polyethylene, polyvinyl alcohol, polyvinyl chloride, polyester, polyvinylidene fluoride, polytetrafluoroethylene, polyimide, epoxy resin, polyurethane, polyether ether ketone, poly (ethylene glycol) and poly (ethylene glycol) copolymer, At least one of polymethyl methacrylate, phenolic resin, modified acrylic acid, modified polyurethane, modified styrene-butadiene rubber derivative, block copolymer or graft copolymer. The binding force between the current collector conductive coating and the current collector is improved by adding the high-molecular binder.

Optionally, the conductive polymer is selected from the group consisting of polythiophene, polypyrrole, polyaniline, polyacetylene, poly-p-phenylene vinylene, polydiyne, and nitroxide organic radical polymerization, and at least one of polythiophene, polypyrrole, polyaniline, polyacetylene, poly-p-phenylene vinylene, polydiyne derivatives, block or graft copolymers, nitroxide organic radical polymerization.

That is, the conductive polymer is selected from at least one of polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene, polyparaphenylethene, polydiyne, and nitroxide-based organic radical polymerization, and a derivative of polythiophene, a block of polythiophene, a graft copolymer of polythiophene, a derivative of polypyrrole, a graft copolymer of block polypyrrole of polypyrrole, a derivative of polyaniline, a block of polyaniline, and a graft copolymer of polyaniline.

Optionally, the conductive powder is selected from at least one of carbon black, acetylene black, carbon nanotubes, carbon fibers, graphite, nano graphite, graphene, fullerene, and conductive oxide. The electron conductivity of the current collector conductive coating is ensured through the conductive powder, so that the performance of the multiplying power performance of an electrochemical system is ensured.

Optionally, the crosslinking component is selected from diacetone acrylamide monomer, or at least one of polyacrylic acid-diacetone acrylamide resin and adipic dihydrazide crosslinking body.

By adding diacetone acrylamide monomer or cross-linked body of polyacrylic acid-diacetone acrylamide resin and adipic dihydrazide as cross-linking agent, and using cross-linking agent to produce cross-linking grafting reaction, the binding force between the current collector conductive coating and the current collector is further increased, and the binding force between the current collector conductive coating and the electrode active substance in the motor layer is also increased, so that the binding force among the current collector, the current collector conductive coating and the electrode layer is improved.

The preparation method of the cross-linked body of polyacrylic acid-diacetone acrylamide resin and adipic dihydrazide is the prior art, and specific reference is made to the content recorded in the paper entitled "preparation of in-situ cross-linked polymer coating" in the international bonding technology workshop of 2013 beijing and the fifth asian bonding technology workshop, which is not repeated herein.

Optionally, the thickness of the current collector conductive coating ranges from 0.05 μm to 5 μm.

On one hand, in order to avoid the problem that the current collector is easy to be corroded by the electrode active material due to insufficient thickness of the current collector conductive coating, and on the other hand, in order to avoid the problem that the electrochemical performance of an electrochemical system is influenced due to too thick thickness of the current collector conductive coating, the thickness of the current collector conductive coating is preferably in a range of 0.05-2 mu m.

Another object of the present invention is to provide a method for preparing the above current collector conductive coating, which comprises the following steps:

s1: mixing a solvent, the high-molecular binder and the conductive powder, and performing premixing and dispersion to obtain a premixed solution;

s2: adding the conductive polymer and the crosslinking component into the premixed solution, and performing premixing and dispersion to obtain conductive coating slurry;

s4: and coating the conductive coating slurry on the surface of a current collector to obtain the conductive coating of the current collector on the surface of the current collector.

Optionally, the solvent is selected from at least one of N-methyl pyrrolidone, deionized water, isopropanol, and absolute ethanol.

Wherein the solvent in step S1 is at least one selected from N-methyl pyrrolidone, deionized water, isopropanol, and anhydrous ethanol; firstly, premixing a high molecular binder and conductive powder in a solvent, and then adding a conductive polymer and a crosslinking component into the obtained premixed liquid to obtain conductive coating slurry; the conductive coating slurry is coated on the surface of a current collector, and the crosslinking component further generates crosslinking grafting reaction under the bonding action of a macromolecular binder and a conductive polymer, so that a current collector conductive coating which is tightly combined with the current collector and has stronger conductive capability is formed on the surface of the current collector.

Specifically, the viscosity range of the conductive coating slurry obtained in the invention is 5-2000 mPa.s, the solid content range is 2-35%, and the pH value range is 2-12.

Optionally, the method further comprises:

s3: and dispersing the conductive coating slurry in a dispersion system for 2-20 times.

In order to uniformly distribute all components in the conductive coating slurry, the preparation method of the current collector conductive coating further disperses the conductive coating slurry before coating the conductive coating slurry on the surface of the current collector, so that the prepared current collector conductive coating has uniform and stable performance; wherein, the dispersing system in the invention is selected from one of a sand mill, a ball mill, a high-speed emulsifying machine, a homogenizer, an ultrasonic pulverizer and a colloid mill.

Optionally, the time for performing the pre-mixing and dispersing in steps S1 and S2 is 0.5 to 3 hours.

Compared with the prior art, the current collector conductive coating provided by the invention has the following advantages:

according to the current collector conductive coating provided by the invention, by adding the conductive polymer, the conductive capability of the current collector conductive coating is favorably improved and the contact internal resistance of an electrochemical system is reduced while the binding force between the conductive coating and a current collector is not influenced, so that the rate capability of the prepared electrochemical system is improved, namely the working performance and the cruising ability of the electrochemical system under a large current are improved; in addition, by adding the crosslinking component, the adhesive force among the current collector, the current collector conductive coating and the electrode active substance can be improved, and the problems of impedance increase, temperature rise and the like of an electrochemical system caused by the falling of a motor layer and the swelling of the conductive coating after long-term circulation of the electrode plate are effectively avoided.

Drawings

FIG. 1 is a graph comparing the peel strengths of electrode sheets according to the present invention;

FIG. 2 is a comparative graph of the cycle performance of a battery 2C prepared by the electrode plate of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.