Preparation method of porous polymer coating for metal negative electrode

Abstract

The invention provides a preparation method of a porous polymer coating for a metal negative electrode. The preparation method mainly comprises the following steps: blending a polymer, a solvent and a non-solvent, and stirring until the polymer is completely dissolved to obtain a coating; coating the surface of a metal negative electrode with the obtained coating; the porous polymer coating is obtained through volatilization of the non-solvent in the drying process. The porous polymer coating is prepared on the surface of the metal negative electrode through a phase inversion method, the preparation method is simple and low in cost, and the prepared porous polymer coating has good ion conduction capability and can effectively inhibit dendritic crystal growth of the metal negative electrode and generation of byproducts, so that the cycle life of the battery is effectively prolonged.

Description

Technical field

[0001] The present invention relates to the technical field of new energy materials, and in particular to a method for preparing a polymer protective layer for a metal battery negative electrode, and in particular to a method for preparing a porous polymer coating for a metal negative electrode. Background Art

[0002] With the depletion of fossil fuels and the increase in carbon emissions, renewable energy sources such as wind and solar energy are developing rapidly. Therefore, efficient energy storage systems continue to be developed to achieve the storage and conversion of these renewable energy sources. Metal batteries with metals such as lithium, zinc, aluminum, tin, and magnesium as negative electrodes have attracted widespread attention due to their high energy density and have been widely researched and applied in recent years. However, these metal negative electrodes are prone to problems such as dendrite growth and by-product production during the cycling process, which can lead to problems such as battery short circuits and performance degradation. Therefore, it is necessary to take certain measures to solve the problems of dendrite growth and by-products. Among them, polymer coating has been proven to be an effective means to solve these problems.

[0003] Polymer coatings have broad research prospects in the field of metal anode protection due to their excellent protective properties. However, the low ion conductivity of typical polymers means that traditional polymer coatings lack a transport channel for metal ions, thus limiting their application in the field of metal anode protection.

[0004] The present invention successfully fabricates a porous polymer coating on the surface of a metal anode using a phase inversion method. The porous structure provides efficient metal ion transport pathways, accelerating the transfer of metal ions and thereby inducing uniform metal ion deposition. Furthermore, the protective effect of the polymer coating effectively suppresses side reactions such as corrosion. The preparation method employed in the present invention is simple, the polymer material used is low-cost, and large-scale preparation is easily achievable. Summary of the Invention

[0005] The purpose of the invention is to use a simple phase inversion method to construct a porous polymer protective layer on the surface of the metal negative electrode, thereby solving the problems of dendrite growth and by-product generation during the use of the metal anode.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The preparation method of the porous polymer coating for the metal negative electrode comprises the following steps:

[0008] (1) blending a polymer material, a first solvent, and a second solvent, and stirring until the polymer is completely dissolved to obtain a coating;

[0009] (2) applying the obtained coating on the surface of the pretreated metal negative electrode;

[0010] (3) Drying until the first solvent and the second solvent are completely volatilized to obtain a porous polymer coating.

[0011] Furthermore, the polymer material in step (1) is at least one of polymethyl methacrylate, polyvinyl acetal, polyacrylonitrile, polyvinylidene fluoride and its copolymer, polyurethane, cellulose acetate, nylon, ethyl cellulose, polydimethylsiloxane, etc.; the first solvent is at least one of acetone, tetrahydrofuran, benzene, xylene, dimethyl sulfoxide, N-methylpyrrolidone, dichloromethane, chloroform, N,N-dimethylformamide, n-butanol, methanol, etc.; the second solvent is at least one of water, ethanol, methanol, acetone, etc.

[0012] Furthermore, the mass concentration of the polymer material in step (1) is 0.1-1000 mg / mL; and the volume ratio of the first solvent to the second solvent is 1:0.001-100.

[0013] Furthermore, the stirring time in step (1) is 0.01-120h, and the temperature during stirring is 0-200°C.

[0014] Furthermore, the metal negative electrode material used in step (2) is at least one of zinc, lithium, aluminum, tin, magnesium, iron, etc.

[0015] Furthermore, the coating method used in step (2) is at least one of blade coating, spin coating, dip coating, spray coating, roller coating, and drop coating.

[0016] Furthermore, in step (3), the drying time is 0.01-120 hours, and the drying temperature is 0-200°C.

[0017] The beneficial effects of the present invention are mainly reflected in:

[0018] (1) A porous polymer coating for metal negative electrode was prepared by phase inversion method. The preparation method is simple, low-cost, and easy to achieve large-scale preparation.

[0019] (2) The structure of the polymer coating was optimized, and the metal ion transport was accelerated by constructing a pore structure.

[0020] (3) By preparing a porous polymer coating on the surface of the metal negative electrode, the problems of dendrite growth and by-product generation of the metal negative electrode are effectively alleviated. DETAILED DESCRIPTION

[0021] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below. Specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] Example 1

[0023] The preparation method of the porous polymer coating for the metal negative electrode comprises the following steps:

[0024] (1) vinylidene fluoride-hexafluoropropylene, acetone, and water were mixed, wherein the mass concentration of vinylidene fluoride-hexafluoropropylene was 47.6 mg / mL, and the volume ratio of acetone to water was 1:0.05, and the mixture was stirred at 25° C. for 12 h until the polymer was completely dissolved to obtain a coating;

[0025] (2) applying the obtained coating to the pretreated zinc foil surface;

[0026] (3) Dry at 25°C for 12 hours.

[0027] Attachment Figure 1 These are scanning electron microscope images of the porous vinylidene fluoride-hexafluoropropylene composite coating (Porous P(VdF-HFP)) obtained in this example and the non-porous vinylidene fluoride-hexafluoropropylene composite coating (P(VdF-HFP)) obtained in Comparative Example 1. It can be seen from the figure that the coating prepared by the phase inversion method exhibits a porous structure, while the surface of the coating prepared without the phase inversion method is relatively dense.

[0028] Attachment Figure 2 The symmetrical cell assembled with the Porous P(VdF-HFP) modified zinc anode (Porous P(VdF-HFP)-Zn) obtained in this example, the P(VdF-HFP) modified zinc anode (P(VdF-HFP)-Zn) obtained in Comparative Example 1, and pure zinc (Bare Zn) at 10 mA cm -2 and 10 mAh cm -2 The test results of the symmetrical battery assembled under the conditions are shown in the figure. It can be seen from the figure that the cycle life of the symmetrical battery assembled with the porous P(VdF-HFP)-Zn electrode obtained in this example can reach 300 hours, which is significantly longer than the 52 hours of the pure zinc electrode. In addition, it can be seen from the figure that the P(VdF-HFP)-Zn electrode exhibits unstable voltage fluctuations at the beginning of the cycle, indicating that the porous polymer coating prepared by the phase inversion method significantly improves the cycle stability of the negative electrode.

[0029] Comparative Example 1

[0030] The difference from Example 1 is that:

[0031] In this comparative example, no water was added in step (1), and the other aspects were the same as in Example 1, and a non-porous P(VdF-HFP) coating was finally obtained.

[0032] Example 2

[0033] The preparation method of the porous polymer coating for the metal negative electrode comprises the following steps:

[0034] (1) polymethyl methacrylate, acetone, and water were mixed, wherein the mass concentration of polymethyl methacrylate was 47.6 mg / mL and the volume ratio of acetone to water was 1:0.05, and stirred at 25° C. for 12 h until the polymer was completely dissolved to obtain a coating;

[0035] (2) applying the obtained coating to the surface of the pretreated zinc sheet;

[0036] (3) Dry at 25°C for 12 hours.

[0037] Example 3

[0038] The preparation method of the porous polymer coating for the metal negative electrode comprises the following steps:

[0039] (1) polyvinyl butyral, acetone, and water were mixed, wherein the mass concentration of polyvinyl butyral was 23.8 mg / mL and the volume ratio of acetone to water was 1:0.05, and the mixture was stirred at 25° C. for 10 h until the polymer was completely dissolved to obtain a coating;

[0040] (2) applying the obtained coating to the surface of the pretreated zinc sheet;

[0041] (3) Dry at 25°C for 24 hours.

[0042] Example 4

[0043] The preparation method of the porous polymer coating for the metal negative electrode comprises the following steps:

[0044] (1) PVDF-HFP, acetone, and water were mixed, wherein the mass concentration of PVDF-HFP was 50 mg / mL, and the volume ratio of acetone to water was 1:0.06, and the mixture was stirred at 40° C. for 10 h until the polymer was completely dissolved to obtain a coating;

[0045] (2) dip-coating the obtained coating on the surface of the pretreated tin sheet;

[0046] (3) Dry at 25°C for 12 hours.

[0047] Example 5

[0048] The preparation method of the porous polymer coating for the metal negative electrode comprises the following steps:

[0049] (1) PVDF-HFP, N-methylpyrrolidone, and ethanol were mixed, wherein the mass concentration of PVDF-HFP was 20 mg / mL, and the volume ratio of N-methylpyrrolidone to ethanol was 1:0.03, and the mixture was stirred at 45° C. for 8 h until the polymer was completely dissolved to obtain a coating;

[0050] (2) applying the obtained coating dropwise onto the surface of the pretreated lithium sheet;

[0051] (3) Dry at 20°C for 18 hours.

Claims

1. A method for preparing a porous polymer coating for a metal negative electrode, characterized in that: The method comprises the following steps: (1) blending a polymer material, a first solvent, and a second solvent, and stirring until the polymer is completely dissolved to obtain a coating; (2) applying the obtained coating on the surface of the pretreated metal negative electrode; (3) Drying until the first solvent and the second solvent are completely volatilized to obtain a porous polymer coating.

2. The method for preparing a porous polymer coating for a metal negative electrode according to claim 1, wherein: The polymer material in step (1) is at least one of polymethyl methacrylate, polyvinyl acetal, polyacrylonitrile, polyvinylidene fluoride and its copolymer, polyurethane, cellulose acetate, nylon, ethyl cellulose, polydimethylsiloxane, etc.; the first solvent is at least one of acetone, tetrahydrofuran, benzene, xylene, dimethyl sulfoxide, N-methylpyrrolidone, dichloromethane, chloroform, N,N-dimethylformamide, n-butanol, methanol, etc.; the second solvent is at least one of water, ethanol, methanol, acetone, etc.

3. The method for preparing a porous polymer coating for a metal negative electrode according to claim 1, wherein: The mass concentration of the polymer material in the step (1) is 0.1-1000 mg / mL; the volume ratio of the first solvent to the second solvent is 1:0.001-100.

4. The method for preparing a porous polymer coating for a metal negative electrode according to claim 1, wherein: The stirring time in step (1) is 0.01-120h, and the temperature during stirring is 0-200°C.

5. The method for preparing a porous polymer coating for a metal negative electrode according to claim 1, wherein: The metal negative electrode material used in step (2) is at least one of zinc, lithium, aluminum, tin, magnesium, iron, etc.

6. The method for preparing a porous polymer coating for a metal negative electrode according to claim 1, wherein: The coating method used in the step (2) is at least one of blade coating, spin coating, dip coating, spray coating, roller coating, and drop coating.

7. The method for preparing a porous polymer coating for a metal negative electrode according to claim 1, wherein: The drying time in step (3) is 0.1-120 hours, and the drying temperature is 0-200°C.

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