Electrode preparation method, electrode prepared thereby, and energy storage device comprising said electrode

Abstract

The present invention relates to an electrode preparation method, an electrode prepared thereby, and an energy storage device comprising said electrode. The preparation method comprises: (1) preparing an electrode film, comprising: (a) material mixing, uniformly mixing an electrode active material, a conductive additive, and a non-fibrillatable binder, then adding a fibrillatable binder, and forming the resulting mixture into a fluffy or dough-like mass; or uniformly mixing an electrode active material, a conductive additive, a non-fibrillatable binder and a fibrillatable binder, and forming the resulting mixture into a fluffy or dough-like mass; and (b) forming, forming the fluffy or dough-like product obtained in step (a) into an electrode film; and (2) current collector depositing, comprising: by means of a physical deposition method, depositing a metal layer on one surface of the electrode film obtained in step (1) as a current collector. The energy storage device in the present invention has improved cycle performance, rate performance, and initial coulombic efficiency.

Description

Electrode preparation method, electrode prepared thereby and energy storage device comprising the electrode

[0001] This application claims priority to Chinese Patent Application No. 202410881839.4, filed on July 2, 2024, the disclosure of which is incorporated herein in its entirety as part of the present application. TECHNICAL FIELD

[0002] The present application relates generally to the field of electrochemistry, in particular to the field of energy storage. Specifically, the present application relates to an electrode preparation method, an electrode prepared thereby, and an energy storage device comprising the electrode, such as a lithium-ion secondary battery, a sodium-ion secondary battery, a lithium-sulfur secondary battery, or a capacitor. BACKGROUND

[0003] Electrodes are important components of electrochemical energy storage devices, such as secondary batteries, and the specific capacity and working voltage of the electrodes can have a great impact on the energy of the electrochemical devices. As the use of energy storage devices in life becomes more and more widespread, people's demand for high-performance (e.g., good cycle performance and rate performance and higher first coulombic efficiency) energy storage devices is increasing. Electrodes are generally prepared by mixing an active material, etc. with a solvent, then coating on a current collector and drying. However, the electrodes prepared by the prior art method still have problems such as low energy density, poor cycle performance and rate performance, and low first coulombic efficiency, which are difficult to meet the increasing demand of people.

[0004] In view of the above problems, those skilled in the art still need to develop a new electrode preparation method, compared to the electrodes prepared by the traditional preparation method, the electrodes prepared by the method have good cycle performance (including improved first discharge specific capacity and cycle discharge specific capacity, meaning higher energy density under the same conditions), rate performance and improved first coulombic efficiency. SUMMARY

[0005] The present application is made in view of the above problems in the prior art.

[0006] In a first aspect, the present application relates to an electrode preparation method, comprising:

[0007] (1) preparing an electrode membrane, comprising:

[0008] (a) mixing

[0009] mixing the electrode active material, the conductive additive, the non-fibrillated binder uniformly, then adding the fibrillated binder, and processing the obtained mixture into a flocculent or muddy shape; or

[0010] mixing the electrode active material, the conductive additive, the non-fibrillated binder and the fibrillated binder uniformly, and processing the obtained mixture into a flocculent or muddy shape;

[0011] (b) forming

[0012] forming the flocculent or muddy product obtained in step (a) into an electrode sheet;

[0013] (2) depositing a current collector, comprising:

[0014] depositing a metal layer as a current collector on one surface of the electrode sheet obtained in step (1) by a physical deposition method.

[0015] The electrode preparation method of the present application does not use solvents such as organic solvents, thereby overcoming some defects of conventional electrode preparation methods, which avoid the use of expensive and toxic organic solvents such as N-methyl pyrrolidone, are environmentally friendly and have cost advantages.

[0016] In addition, compared with the electrode prepared by the conventional electrode preparation method (e.g. coating the electrode active material on the current collector), the electrode active material, the conductive additive, the non-fibrillated cellulose and the fibrillated cellulose are mixed and then formed into an electrode sheet, and then the current collector is deposited on the obtained electrode sheet, thereby significantly reducing the volume and mass ratio of the sheet-shaped current collector for coating the active material in the energy storage device, and improving the mass specific capacity and volume specific capacity of the energy storage device.

[0017] Further, the inventors surprisingly found that, compared with the conventional electrode obtained by coating the positive and negative electrode active materials on the positive and negative electrode current collectors, in addition to the increase in specific capacity due to the reduction in the mass and volume of the auxiliary components, in the electrode prepared by the method of the present application, the electrode active material has improved first discharge specific capacity and cycle discharge specific capacity, even at an increased charge-discharge rate. This is beneficial to improve the energy density of the energy storage device and improve the cycle performance and rate performance of the energy storage device. In addition, compared with the conventional electrode obtained by coating the positive and negative electrode active materials on the positive and negative electrode current collectors, the energy storage device comprising the electrode prepared by the method of the present application also has improved first coulombic efficiency.

[0018] In addition, the inventors also unexpectedly found that by adjusting the addition order of the fibrillated binder, the treatment temperature of the electrode sheet, and / or the temperature of the physical deposition process, etc., the first coulombic efficiency or discharge specific capacity can be further improved, and / or the peeling force between the current collector and the electrode sheet can be increased or the impedance of the electrode sheet can be reduced.

[0019] The electrode prepared by the electrode preparation method of the first aspect of the present application has improved cycle performance (including improved first discharge specific capacity and cycle discharge specific capacity) and rate performance, and higher first coulombic efficiency.

[0020] Alternatively or additionally, the electrode prepared by the electrode preparation method of the first aspect of the present application has improved peel strength between the current collector and the electrode film.

[0021] Alternatively or additionally, the electrode prepared by the electrode preparation method of the first aspect of the present application has reduced impedance.

[0022] In a second aspect, the present application relates to an electrode prepared by the electrode preparation method according to the first aspect of the present application.

[0023] In a third aspect, the present application relates to an energy storage device comprising a positive electrode and a negative electrode, wherein at least one of the positive electrode and the negative electrode, preferably both the positive electrode and the negative electrode, comprise the electrode according to the second aspect of the present application.

[0024] The present application will be described in detail below by way of exemplary embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0025] To make the technical solutions of the present application clearer, the accompanying drawings required for describing the embodiments will be briefly described below. It should be understood that these drawings are only for the purpose of making it easier for the skilled person to understand the present application, and are not intended to limit the scope of the present application.

[0026] Figure 1 is a scanning electron microscope picture of the positive electrode film 21 prepared in Example 1.

[0027] Figure 2 is a scanning electron microscope picture of the positive electrode film 22 prepared in Example 1.

[0028] Figure 3 is a cyclic voltammogram of the CR2032 button half-cell assembled by the negative electrode 1 and the negative electrode 2 prepared in Example 2.

[0029] Figure 4 is a galvanostatic first charge-discharge curve showing the CR2032 button half-cell assembled by the negative electrode 1 and the negative electrode 2 prepared in Example 2.

[0030] Figure 5 is a heat flow curve showing the negative electrode film 6 prepared in Example 4.

[0031] Figure 6 shows the galvanostatic first charge-discharge curves of the CR2032 button half-cells respectively assembled by the negative electrode 6 and the negative electrode 7 prepared in Example 4.

[0032] Figure 7 shows the comparison of the first coulombic efficiency of the CR2032 button half-cells respectively assembled by the negative electrode 6 and the negative electrode 7 prepared in Example 4.

[0033] Figure 8 is a graph showing the electrochemical impedance (ohm) spectra of the positive electrode 26, the positive electrode 27 and the positive electrode 28 respectively prepared according to Example 5.

[0034] FIG. 9 is a graph showing the discharge specific capacity (mAh / g) of the negative electrode active material and the entire negative electrode of the negative electrode 11 and the negative electrode 12, respectively, with respect to the cycle number.

[0035] FIG. 10 is a graph showing the discharge specific capacity (mAh / g) of the positive electrode active material and the entire positive electrode of the positive electrode 29 and the positive electrode 30, respectively, at different rates with respect to the cycle number.

[0036] FIG. 11 is a graph showing the discharge specific capacity (mAh / g) of the entire battery of the secondary battery 1 and the secondary battery 2 with respect to the cycle number.

[0037] FIG. 12 is a graph showing the charge-discharge voltage (V) versus the discharge specific capacity (mAh / g) of the entire battery of the secondary battery 1 and the secondary battery 2 for the first charge-discharge cycle. DETAILED DESCRIPTION

[0038] In order to make the purposes, technical solutions and beneficial technical effects of the present application clearer, the present application will be described in detail below. It should be noted that the various aspects, features, embodiments, and advantages described in the present application can be compatible and / or combined together.

[0039] Unless otherwise specified, the meanings of the scientific and technical terms in the present specification are the same as those generally understood by those skilled in the art.

[0040] The present application relates to an electrode preparation method and an electrode prepared thereby, and an energy storage device, such as a lithium-ion secondary battery, a sodium-ion secondary battery, a lithium-sulfur secondary battery, or a capacitor, a supercapacitor, a lithium-ion capacitor, comprising the electrode.

[0041] The present application will be described in detail below.

[0042] Electrode preparation method

[0043] In a first aspect, the present application relates to an electrode preparation method, comprising:

[0044] (1) preparing an electrode film, comprising:

[0045] (a) mixing

[0046] mixing the electrode active material, the conductive additive, the non-fibrillated binder uniformly, then adding the fibrillated binder, and processing the resulting mixture into a flocculent or muddy shape; or

[0047] mixing the electrode active material, the conductive additive, the non-fibrillated binder and the fibrillated binder uniformly, and processing the resulting mixture into a flocculent or muddy shape;

[0048] (b) forming

[0049] forming the flocculent or muddy product obtained in step (a) into an electrode sheet;

[0050] (2) depositing a current collector, comprising:

[0051] depositing a metal layer as a current collector on one surface of the electrode sheet obtained in step (1) by a physical deposition method.

[0052] The electrode preparation method of the present application does not use solvents such as organic solvents, thereby overcoming some defects of conventional electrode preparation methods, which avoid the use of expensive and toxic organic solvents such as N-methyl pyrrolidone, are environmentally friendly and have cost advantages.

[0053] In addition, compared with the electrode prepared by the conventional electrode preparation method (e.g., coating the electrode active material on the current collector), the electrode active material, the conductive additive, the non-fibrillated cellulose and the fibrillated cellulose are mixed in the present application, and then the electrode sheet is obtained by forming, and then the current collector is deposited on the obtained electrode sheet, thereby significantly reducing the volume and mass ratio of the sheet-shaped current collector for coating the active material in the energy storage device, and improving the mass specific capacity and volume specific capacity of the energy storage device.

[0054] Further, the inventors surprisingly found that, compared with the conventional electrode obtained by coating the positive and negative active materials on the positive and negative current collectors, in addition to the increase in specific capacity due to the reduction in the mass and volume of the auxiliary components, in the electrode prepared by the method of the present application, the electrode active material has improved first discharge specific capacity and cycle discharge specific capacity, even at an increased charge-discharge rate. This is beneficial to improve the energy density of the energy storage device and improve the cycle performance and rate performance of the energy storage device. In addition, compared with the conventional electrode obtained by coating the positive and negative active materials on the positive and negative current collectors, the energy storage device comprising the electrode prepared by the method of the present application also has improved first coulombic efficiency.

[0055] In addition, the inventors also unexpectedly found that by adjusting the addition order of the fibrillated binder, the treatment temperature of the electrode sheet, and / or the temperature of the physical deposition process, etc., the first coulombic efficiency or discharge specific capacity can be further improved, and / or the peeling force between the current collector and the electrode sheet can be increased or the impedance of the electrode sheet can be reduced.

[0056] The electrode preparation method of the present application comprises preparing an electrode sheet and depositing a current collector. Each step will be described in detail below.

[0057] Preparation of the electrode sheet

[0058] The preparation of the electrode sheet comprises a mixing and forming step.

[0059] It is noted that the term "electrode sheet" refers to a sheet (i.e. active material layer) prepared from a mixture of electrode active material, conductive additive, binder, etc., and does not include a current collector. In contrast, the term "electrode" or "electrode sheet" includes not only the "electrode sheet" but also a "current collector".

[0060] Mixing

[0061] The purpose of the mixing process is to obtain a mixture of electrode active material, conductive additive, non-fibrillated binder, and optional fibrillated binder, to facilitate the subsequent steps.

[0062] In some embodiments, the mixing process mixes the electrode active material, conductive additive, non-fibrillated binder, and fibrillated binder uniformly, and processes the resulting mixture into a flocculent or muddy state.

[0063] The inventors have found in their research that the addition of non-fibrillated binder helps to alleviate stress during the rolling process, to avoid the particles from being pressed into a hard and brittle mass, and thus to avoid cracks on the surface of the electrode sheet. In addition, the inventors have also unexpectedly found that the addition of non-fibrillated binder can significantly reduce the electrode side reactions and improve the initial coulombic efficiency.

[0064] In contrast to the non-fibrillated binder, the addition of fibrillated binder can be subjected to a fibrillation process, to process the resulting mixture into a flocculent or muddy state. In this context, the term "fibrillation" refers to the "fibrillated binder" originally in a granular state being stretched into a fibrous state under the action of mechanical shear force, and being entangled with the electrode active material and conductive additive, etc., to form a three-dimensional network. The inventors have also unexpectedly found in their research that the order of addition of the fibrillated binder during the mixing process can have a significant impact on the initial coulombic efficiency and discharge specific capacity, such as the initial discharge specific capacity. Specifically, the later the order of addition of the fibrillated binder during the mixing process, the higher the initial coulombic efficiency and discharge specific capacity, such as the initial discharge specific capacity, of the energy storage device, such as a secondary battery, such as a lithium-ion secondary battery.

[0065] Therefore, in preferred embodiments, the mixing process mixes the electrode active material, conductive additive, and non-fibrillated binder uniformly, then adds the fibrillated binder, and processes the resulting mixture into a flocculent or muddy state.

[0066] It is to be noted that the term "fibrillated binder" refers to a binder component that is subjected to shear force during the electrode film preparation process, and as a result, the structure slips and extends into a fiber network having a winding and coating function in the electrode structure. In contrast, the term "non-fibrillated binder" refers to a binder component that is dissolved / melted by a solvent or heat, thereby forming a coating within the electrode, and achieving adhesion using interaction forces (including van der Waals forces, hydrogen bonds, covalent interactions, etc.) with each component of the electrode. Thus, the "fibrillated binder" is different from the "non-fibrillated binder".

[0067] The preparation method of the present application does not have a particular requirement for the type of non-fibrillated binder, and any type of non-fibrillated binder commonly used in the art can be used. As an example, the non-fibrillated binder is selected from one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose, polyacrylic acid, sodium alginate, poly(ethylene oxide), polyacrylonitrile (PAN), polyvinyl alcohol, polyimide (PI), cellulose, and cellulose derivatives (e.g., cellulose acetate, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), nitrocellulose, carboxymethyl cellulose (CMC), carboxyethyl cellulose, carboxypropyl cellulose, carboxyisopropyl cellulose, sodium cellulose, sodium nitrocellulose, and sodium carboxyalkyl cellulose), preferably one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose, polyacrylic acid, and sodium alginate.

[0068] Similarly, the preparation method of the present application does not have a particular requirement for the type of fibrillated binder, and any type of fibrillated binder commonly used in the art can be used. As an example, the fibrillated binder is selected from polytetrafluoroethylene. Preferably, the volume average particle diameter D v 50is in the range of 0.1-1000 μm, preferably 200-600 μm. v 50Particle diameter refers to a value at which the particles (e.g., fibrillated binder) each occupying 50% of the total sample volume are present in the volume cumulative distribution curve of the particles (e.g., fibrillated binder) less than the particle diameter value and greater than the particle diameter value. The D v 50Particle diameter can be measured by a method commonly used by those skilled in the art. As an example, a laser particle size analyzer can be used.

[0069] Similarly, the preparation method of the present application does not have a particular requirement for the type of conductive additive, and any conductive additive commonly used in the art can be used. As an example, the conductive additive can be selected from one or more of graphite, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0070] As will be readily appreciated by those skilled in the art, in addition to the electrode active material, the electrically conductive additive, the non-fibrillar binder, and the fibrillar binder, other commonly used materials for electrode preparation, such as thickening agents, film formation promoters, and the like, can be added during the mixing process.

[0071] In some embodiments, the weight ratio of the amount of the fibrillar binder added to the amount of the non-fibrillar binder added is in the range of 0.1:1 to 10:1, preferably 0.1:1 to 3.0:1, based on the total weight of all components subjected to mixing, such as 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 2.0:1, 2.5:1, 3.0:1, 4.0:1, 5.0:1, 6.0:1, 8.0:1, 10.0:1, or a range defined by any two of them. When the amount of the fibrillar binder added to the amount of the non-fibrillar binder added is in the above range, the fibrillar binder and the non-fibrillar binder work better in synergy, which is advantageous for improving the cycle performance (including the initial discharge capacity and the cycle discharge capacity), the rate capability, and the initial coulombic efficiency.

[0072] In some embodiments, the electrode active material is added in an amount of 80-98 wt.%, preferably 90-98 wt.%, based on the total weight of all components being mixed; the electrically conductive additive is added in an amount of 0.5-10 wt.%; the non-fibrillated binder is added in an amount of 0.5-10 wt.%, preferably 1-8 wt.%; and the fibrillated binder is added in an amount of 0.5-10 wt.%, preferably 1-5 wt.%. Those skilled in the art will readily appreciate that the total weight of all components being mixed is 100%. By way of example, the fibrillated binder can be added in an amount of 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, 2.5 wt.%, 3.0 wt.%, 3.5 wt.%, 4.0 wt.%, 4.5 wt.%, 5.0 wt.%, 5.5 wt.%, 6.0 wt.%, 6.5 wt.%, 7.0 wt.%, 7.5 wt.%, 8.0 wt.%, 8.5 wt.%, 9.0 wt.%, 9.5 wt.%, 10.0 wt.%, or within a range defined by any two of them, and / or the non-fibrillated binder can be added in an amount of 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, 2.5 wt.%, 3.0 wt.%, 3.5 wt.%, 4.0 wt.%, 4.5 wt.%, 5.0 wt.%, 5.5 wt.%, 6.0 wt.%, 6.5 wt.%, 7.0 wt.%, 7.5 wt.%, 8.0 wt.%, 8.5 wt.%, 9.0 wt.%, 9.5 wt.%, 10.0 wt.%, or within a range defined by any two of them, based on the total weight of all components being mixed.

[0073] In some embodiments, the total amount of the non-fibrillated binder and the fibrillated binder is 1-15 wt.%, preferably 1-10 wt.%, based on the total weight of all components being mixed. For example, the total amount of the non-fibrillated binder and the fibrillated binder can be 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, 2.5 wt.%, 3.0 wt.%, 3.5 wt.%, 4.0 wt.%, 4.5 wt.%, 5.0 wt.%, 5.5 wt.%, 6.0 wt.%, 6.5 wt.%, 7.0 wt.%, 7.5 wt.%, 8.0 wt.%, 8.5 wt.%, 9.0 wt.%, 9.5 wt.%, 10.0 wt.%, 10.5 wt.%, 11.0 wt.%, 11.5 wt.%, 12.0 wt.%, 12.5 wt.%, 13.0 wt.%, 13.5 wt.%, 14.0 wt.%, 14.5 wt.%, 15.0 wt.%, or within a range defined by any two of them, based on the total weight of all components being mixed.

[0074] For the content of each of the above components, those skilled in the art will readily appreciate that, after the electrode membrane is prepared, the content of each of the above components is also within the above range, based on the dry weight of the electrode membrane.

[0075] The mixing method of the electrode preparation method of the present application is not particularly limited, and a mixing method commonly used in the art can be used. For example, the mixture can be mixed by one or more of ball milling, jet milling, high-speed shearing, or mechanical milling. For example, a person skilled in the art can mix by a planetary ball mill or mechanical stirring. For example, when mixing by mechanical stirring, the rotation speed of the mechanical stirring can be controlled to be in the range of 50-10000 rpm, for example, 50 rpm, 100 rpm, 300 rpm, 500 rpm, 1000 rpm, 2000 rpm, 3000 rpm, 5000 rpm, 8000 rpm, 10000 rpm, or a range defined by any two of them, and / or the mixing time is in the range of 5-720 minutes, for example, 5 minutes, 30 minutes, 60 minutes, 120 minutes, 240 minutes, 300 minutes, 360 minutes, 420 minutes, 720 minutes, or a range defined by any two of them. In addition, for example, zirconium oxide can be used as a ball milling medium, and the volume fraction of zirconium oxide is less than 30%. A person skilled in the art can easily understand that the flocculation or mud processing of the mixture added with the fibrillated binder can also be carried out by one or more of ball milling, jet milling (i.e. air flow milling or energy flow milling), high-speed shearing, or mechanical milling. Therefore, preferably, in the embodiments, the mixture added with the fibrillated binder is processed into flocculation or mud while being mixed.

[0076] Molding

[0077] The molding method of the flocculation or mud product of the present application is not particularly limited, and a technical means commonly used by a person skilled in the art can be used. For example, the flocculation or mud product can be molded into an electrode film by one or more of roll pressing (e.g. hot roll molding), extrusion molding, injection molding, blow molding, coating molding, or casting molding, preferably roll pressing (e.g. hot roll molding) or extrusion molding. Hot roll molding refers to the molding of the fibrillated electrode material by hot roll press multiple times. During the roll pressing process, the flocculation or mud powder is molded, and with the increase of pressure and times, the thickness of the electrode film is continuously thinned, and the compaction density is continuously improved. Heating can improve the flowability of the polymer, improve the processability of the electrode film, and on the other hand, can also make the non-fibrillated binder melt and uniformly coat and bond the other components of the electrode film, so as to achieve a closer adhesion between the components of the electrode film. For example, during the hot roll molding process, the roll pressing pressure can be controlled in the range of 0.1 x 10 3 -20.0 x 10 3 kgf / cm 2 , the roll pressing temperature is in the range of 10-200℃, the roll pressing speed is 0.5-50 m / min, and the roll pressing times are 1-30 times. For example, the roll pressing pressure can be 0.1 x 10 30.2 x 10 3 0.3 x 10 3 0.5 x 10 3 0.8 x 10 3 1.0 x 10 3 2.0 x 10 3 5.0 x 10 3 10.0 x 10 3 15.0 x 10 3 20.0 x 10 3 kgf / cm 2 or any two of them, and / or the roll temperature can be in the range of 10, 20, 30, 40, 50, 60, 70, 80, 100, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 °C, or any two of them.

[0078] In some embodiments, preferably, there is no pre-forming step before step (b) is performed. Not performing a pre-forming step helps to batch produce the electrode film, simplifies the process, and improves production efficiency.

[0079] In some embodiments, after the electrode film piece is prepared, the resulting electrode film piece is kept at a temperature of 100-250 °C, preferably 150-200 °C, preferably in vacuum, for 4-20 h, preferably 8-16 h. By subjecting the electrode film piece to the above heat treatment, the initial coulombic efficiency can be improved. This is believed to be due to the fact that the above heat treatment helps to reduce side reactions of the electrode during charge and discharge. As an example, the temperature at which the resulting electrode film piece is treated can be in the range of 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250 °C, or any two of them, and / or the treatment time can be in the range of 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 h, or any two of them.

[0080] In some embodiments, the thickness of the electrode film produced in the forming step is 10-1000 μm, preferably 50-200 μm. By way of example, the thickness of the electrode film produced in the forming step can be 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 220, 240, 260, 280, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000 μm, or a range defined by any two of them.

[0081] depositing a current collector

[0082] After the electrode film is produced, a metal layer is deposited on one surface of the resulting electrode film as a current collector by a physical deposition method, thereby obtaining an electrode.

[0083] In some embodiments, before the current collector is deposited on the electrode film by a physical deposition method, a patterned mask is applied on the surface of the electrode film on which the current collector is to be deposited. For example, the patterned mask can be selected from a rectangle, a triangle, a ring, and the like. The application of the patterned mask is advantageous in reducing the amount of the deposited current collector, saving cost; and a good current conduction effect can be maintained with a reduced deposition amount by the design of the mask pattern.

[0084] In some embodiments, before the current collector is deposited on the electrode film by a physical deposition method, a pretreatment step selected from at least one of the following is performed on the electrode film: plasma cleaning and surface etching.

[0085] In some embodiments, the electrode film is pretreated by plasma. For example, a vacuum or non-vacuum plasma cleaning can be performed, and oxygen, helium, argon or xenon can be used as the process gas.

[0086] In some embodiments, the electrode film is pretreated by surface etching. For example, oxygen can be used as the etchant, and the etching time is for example 1-20 min, preferably 1-10 min.

[0087] In the present application, a current collector is deposited on one surface of the electrode film by a physical deposition method. By way of example, the physical deposition method (physical vapor deposition method) can be selected from one or more of sputter plating (e.g. magnetron sputtering), evaporation plating or ion plating.

[0088] In some embodiments, the physical deposition method is magnetron sputtering. For example, the target material of the magnetron sputtering is selected from a metallic material, for example, one or more of the elements selected from copper, aluminum, nickel, titanium, tin, iron, gold, platinum or alloys thereof. The process conditions of the magnetron sputtering are as follows: the substrate temperature is 10-300°C, preferably 20-200°C, the substrate (i.e. the electrode membrane) rotation speed is 0-20 rpm, the target-substrate distance is 50-200 mm; the main chamber vacuum degree is 5x10 -3 -5x10 -6 Pa, the process gas pressure is 0.5-15 Pa, the power supply power is 20-500 W, and the sputtering time is 20-5000 s. The inventors have found that by adjusting the substrate temperature during the magnetron sputtering process, it is beneficial to improve the peeling force between the current collector and the electrode membrane and reduce the impedance. As an example, the substrate temperature during the magnetron sputtering process can be 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300°C, or within a range defined by any two of them.

[0089] In some embodiments, the thickness of the current collector prepared by the electrode preparation method of the present application is 0.1-10 μm, preferably 0.5-2 μm. As an example, the thickness of the current collector can be 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0 μm, or within a range defined by any two of them.

[0090] In some embodiments, the ratio of the thickness of the current collector to the thickness of the electrode membrane prepared by the method of the present application is in the range of 0.0001:1 to 0.1000:1, preferably 0.005:1 to 0.0300:1. As an example, the ratio of the thickness of the current collector to the thickness of the electrode membrane can be 0.0001:1, 0.0050:1, 0.0100:1, 0.0200:1, 0.0300:1, 0.0400:1, 0.0500:1, 0.0600:1, 0.0700:1, 0.0800:1, 0.0900:1, 0.1000:1, or within a range defined by any two of them.

[0091] Electrode

[0092] The second aspect of the present application provides an electrode prepared by the electrode preparation method according to the first aspect of the present application.

[0093] Energy storage device

[0094] The third aspect of the present application provides an energy storage device comprising a positive electrode and a negative electrode, wherein at least one of the positive electrode and the negative electrode, preferably both the positive electrode and the negative electrode, comprise an electrode according to the second aspect of the present application.

[0095] In some embodiments, the energy storage device is a lithium-ion secondary battery, a sodium-ion secondary battery, a lithium-sulfur secondary battery, or a capacitor, a supercapacitor, a lithium-ion capacitor, preferably a lithium-ion secondary battery, a sodium-ion secondary battery.

[0096] The energy storage device of the present application is described below by way of example of a lithium-ion secondary battery. It is readily understood by the person skilled in the art that the description with respect to a lithium-ion secondary battery can be adapted to obtain a sodium-ion secondary battery, a lithium-sulfur secondary battery, or a capacitor, a supercapacitor, a lithium-ion capacitor of the present application.

[0097] Lithium-ion secondary battery

[0098] In some embodiments, the energy storage device of the present application is a lithium-ion secondary battery.

[0099] The present application does not particularly require the type of the positive electrode active material of the lithium-ion secondary battery, and any positive electrode active material commonly used in the art can be employed. In some embodiments, the positive electrode active material is selected from one or more of, for example, lithium transition metal complex oxides, complex oxides obtained by adding other transition metals or non-transition metals or non-metals to the lithium transition metal complex oxides. In some embodiments, the layered transition metal oxide can have a general formula Li x M y O2, wherein M is selected from one or more of Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce and Mg, the general formula satisfying the valence balance. In addition, the layered transition metal oxide can also be doped with an element having a large electronegativity, such as one or more of S, N, F, Br, Cl, I, CN, etc. For example, the positive electrode active material can be selected from one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, lithium phosphate containing olivine structure, such as LiFeMnPO4, LiCoO2, LiMn2O4, LiNiMnCoO2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiFePO4, LiNiCoAlO2, and Li2TiO, etc.

[0100] In some embodiments, the amount of the positive active material is 80-98 wt%, preferably 90-98 wt%, based on the dry weight of the positive electrode sheet.

[0101] In some embodiments, any negative active material commonly used by those skilled in the art can be employed. For example, the negative active material can be one or more of natural graphite, artificial graphite, meso-carbon microbe (MCMB), hard carbon, soft carbon, silicon-based material, tin-based material, lithium titanate, and metallic sodium, preferably one or more of graphite and silicon-based material, more preferably one or more of graphite, silicon-carbon composite, and silicon alloy.

[0102] In some embodiments, the amount of the negative active material is 80-98 wt%, preferably 90-98 wt%, based on the dry weight of the negative electrode sheet.

[0103] Those skilled in the art will readily understand that, when the energy storage device of the present application is a secondary battery, the secondary battery further comprises an electrolyte.

[0104] In some embodiments, the electrolyte is a non-aqueous liquid electrolyte. The present application does not particularly require the type of the non-aqueous liquid electrolyte. The non-aqueous liquid electrolyte comprises a non-aqueous organic solvent and an electrolyte lithium salt.

[0105] In some embodiments, the non-aqueous organic solvent can be selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0106] In some embodiments, the electrolyte lithium salt can be selected from one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroborate (LiBF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethylsulfonylimide (LiTFSI), lithium trifluoromethylsulfonate (LiTFS), lithium difluoro-oxalato-borate (LiDFOB), lithium bis-oxalato-borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluoro-di-oxalato-phosphate (LiDFOP), and lithium tetrafluoro-oxalato-phosphate (LiTFOP).

[0107] In some embodiments, the concentration of lithium ions in the non-aqueous liquid electrolyte is 0.5 to 1.5 mol / L, for example, 0.8-1.2 mol / L.

[0108] In some embodiments, the non-aqueous liquid electrolyte also optionally includes an additive. As an example, the additive can include an additive that facilitates negative electrode film formation or an additive that facilitates positive electrode film formation, and can also include an additive that improves battery performance, for example, an additive that improves battery performance at high or low temperatures, etc.

[0109] As will be readily understood by one skilled in the art, when the electrolyte is a liquid electrolyte, the lithium ion secondary battery also includes a porous separator. The present application does not have a particular limitation on the porous separator used, and a commonly used porous separator having electrochemical stability and chemical stability can be used, for example, it can be a single layer or a multi-layer film of one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride, for example, a PP / PE / PP three-layer porous film. When a solid electrolyte is used, the separator can also be omitted.

[0110] In some embodiments, the electrolyte is a gel electrolyte. The present application does not have a particular requirement for the type of gel electrolyte, and any gel electrolyte conventionally used in the art can be used. In some embodiments, the gel electrolyte can include a polymer matrix, and a liquid electrolyte including a lithium salt and a non-aqueous organic solvent. The polymer matrix can be selected from one or more of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer P(VDF-HFP), polyethylene oxide (PEO), polyacrylonitrile (PAN), and polymethyl methacrylate (PMMA). The liquid electrolyte can be the same as described above.

[0111] Similarly, as will be readily understood by one skilled in the art, when the electrolyte is a gel electrolyte, a porous separator can also be optionally included. The gel electrolyte can be at least partially filled in the pores of the porous separator. The description of the porous separator is the same as that of the porous separator used with the liquid electrolyte.

[0112] In some embodiments, the electrolyte is a solid-state electrolyte. The present application does not have a particular requirement for the type of solid-state electrolyte, and any solid-state electrolyte conventionally used in the art can be used. The solid-state electrolyte can be selected from one or more of inorganic solid-state electrolytes or polymer electrolytes, preferably one or more of oxides, sulfides and polymers. For example, the solid-state electrolyte can be selected from one or more of lithium garnet oxide (Li7La3Zr2O12, abbreviated as LLZO), tin oxide (SnO2), bismuth oxide (Bi2O3), lithium sulfide (Li2S), sodium sulfide (Na2S), silicates, phosphates, siloxanes, perovskite oxides, lithium oxides and polymer solid-state electrolytes, etc. 12

[0113] The above describes the energy storage device of the present application by taking a lithium-ion secondary battery as an example. It is easy for those skilled in the art to understand that the energy storage device of the present application can also be a sodium-ion secondary battery, a lithium-sulfur secondary battery or a capacitor (e.g. a supercapacitor, a lithium-ion capacitor), and those skilled in the art can refer to the above-described lithium-ion secondary battery and make appropriate adjustments to obtain the sodium-ion secondary battery, the lithium-sulfur secondary battery or the capacitor (e.g. the supercapacitor, the lithium-ion capacitor) of the present application.

[0114] In some embodiments, the energy storage device of the present application is a sodium-ion secondary battery. When the energy storage device is a sodium-ion secondary battery, the positive electrode active material is selected from one or more of layered transition metal oxides or Prussian blue analogues, preferably Na2FeFe(CN)6(NaHCF), NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, Na2FeP2O7, Na4Fe3(PO4)2(P2O7), Na3V2(PO4)3, NaFePO4 and NaMnFe(CN)6, etc., preferably the amount of the positive electrode active material is 80-98 wt.%, preferably 90-98 wt.%, based on the dry weight of the positive electrode film; and / or

[0115] The negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon-based materials, tin-based materials, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composite, silicon alloy, preferably the amount of the negative electrode active material is 80-98 wt.%, preferably 90-98 wt.%, based on the dry weight of the negative electrode film.

[0116] ​In some embodiments, the energy storage device of the present application is a lithium-sulfur secondary battery. When the energy storage device is a lithium-sulfur secondary battery, the positive electrode active material is selected from one or more of inorganic compounds such as lithium sulfide, titanium sulfide, phosphorus sulfide, or organic compounds having one or more of straight-chain alkyl, branched-chain alkyl, cycloalkane, arene, heteroatom-containing arene, sulfur-combined compounds, preferably one or more of sulfur-carbon composite positive electrode materials, sulfurized polyacrylonitrile, preferably, the amount of the positive electrode active material is 80-98 wt.%, preferably 90-98 wt.%, based on the dry weight of the positive electrode film; and / or

[0117] The negative electrode active material can be a negative electrode active material commonly used in lithium-sulfur secondary batteries, for example, selected from metal lithium, preferably, the amount of the negative electrode active material is 80-99 wt.%, preferably 90-99 wt.%, based on the dry weight of the electrode film.

[0118] In some embodiments, the energy storage device of the present application is a capacitor. When the energy storage device is a capacitor, the positive electrode active material is selected from one or more of metal oxides, conductive polymers, carbon materials, preferably one or more of MnO2, NiO, Co3O4, polyaniline, polypyrrole, activated carbon, graphene, biochar, preferably, the amount of the positive electrode active material is 80-98 wt.%, preferably 90-98 wt.%, based on the dry weight of the positive electrode film; and / or

[0119] The negative electrode active material is selected from one or more of metals, carbon materials, conductive polymers, metal oxides, metal-organic framework (MOF) derived materials, preferably one or more of aluminum, zinc, activated carbon, graphite, polyaniline, polypyrrole, polythiophene, MnO2, preferably, the amount of the negative electrode active material is 80-98 wt.%, preferably 90-98 wt.%, based on the dry weight of the negative electrode film.

[0120] For supercapacitors or lithium-ion capacitors, those skilled in the art can refer to the above embodiments with appropriate adjustments.

[0121] Examples

[0122] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0123] I. Measurement method

[0124] 1. Scanning electron microscope test

[0125] The prepared electrode film is fixed on a sample stage and sent into a scanning electron microscope (Zeiss Gemini) sample chamber to observe the surface morphology of the electrode film.

[0126] 2. Volume average particle size D v 50

[0127] The sample to be tested is added to an appropriate amount of ethanol solvent so that the concentration of the sample to be tested is 0.01 g / L, and ultrasonic dispersion is performed to form a dispersion liquid. Then, a Mastor 2000 laser particle size analyzer is used for testing to obtain equivalent particle size distribution information.

[0128] 3. Peeling force

[0129] The active material side of the composite electrode to be tested is fixed on a substrate placed horizontally, and a test tape is attached on the current collector side. The tape and the substrate are fixed on a universal testing machine ZWICKZ020 through clamps, respectively, and the two ends are 180°. Stretching is started at a rate of 5 cm / min, i.e. current collector peeling on the electrode surface, and the peeling force and displacement information are recorded.

[0130] 4. Thermal performance test

[0131] Differential scanning calorimetry (DSC) is used for testing, and the heat absorption and release information of the electrode film during the heating process is recorded to characterize the phase transition of the non-fibrillated binder during heat treatment. The test conditions are as follows: using Q5000IR instrument, argon atmosphere, heating rate of 10°C / min from 20°C to 300°C. The signal recorded during the heating process is taken as the measurement result.

[0132] 5. Electrode electrochemical performance test

[0133] 5.1 Cyclic voltammetry curve

[0134] Cyclic voltammetry test is performed using an electrochemical workstation (CHI660e, Chenhua). The voltage range is 0.005V-2V. The cyclic voltammetry curve is measured at a scan rate of 1mV s-1. During the measurement, the voltage is first reduced from 2V to 0.005V, and then increased from 0.005V to 2V.

[0135] 5.2 Impedance

[0136] Electrochemical impedance is measured using CHI660e of Chenhua. The electrochemical impedance measurement conditions are: frequency range 100kHz to 0.01Hz, and alternating current voltage amplitude 10mV.

[0137] 5.3 Battery charge and discharge test

[0138] Battery cycle data is collected at room temperature using a battery tester (LAND, 2001CT).

[0139] 5.3.1 Lithium ion battery charge and discharge test

[0140] Half-cell charge-discharge test

[0141] The negative half-cell charge-discharge test condition is: at a temperature of 30°C, charge the CR2032 button half-cell to 1.5V with a current of 0.5C rate, then stand for 5min, then discharge to 0.005V with a current of 0.5C rate, then stand for 5min, which is one charge-discharge cycle. Record the discharge capacity and charge capacity at the first charge-discharge cycle as the first discharge capacity (i.e. the delithiation capacity, same below) and the first charge capacity (i.e. the lithiation capacity, same below). Similarly, record the discharge capacity and charge capacity at the n-th cycle as the n-th discharge capacity and the n-th charge capacity, respectively.

[0142] The positive half-cell charge-discharge test condition is: at a temperature of 30°C, charge the CR2032 button half-cell to 4.3V with a current of 0.5C rate, then stand for 5min, then discharge to 3.0V with a current of 0.5C rate, then stand for 5min, which is one charge-discharge cycle. Record the discharge capacity and charge capacity at the first charge-discharge cycle as the first discharge capacity and the first charge capacity. Similarly, record the discharge capacity and charge capacity at the n-th cycle as the n-th discharge capacity and the n-th charge capacity, respectively.

[0143] Full-cell charge-discharge test:

[0144] The full-cell charge-discharge test condition for the assembled full cell is: at a temperature of 30°C, charge the cell to 4.3V with a current of 0.5C rate, then stand for 5min, then discharge to 3.0V with a current of 0.5C rate, then stand for 5min, which is one charge-discharge cycle. Record the discharge capacity and charge capacity at the first charge-discharge cycle as the first discharge capacity and the first charge capacity. Similarly, record the discharge capacity and charge capacity at the n-th cycle as the n-th discharge capacity and the n-th charge capacity, respectively.

[0145] Divide the measured discharge capacity by the mass of the negative electrode to obtain the discharge capacity of the whole negative electrode; divide the measured discharge capacity by the mass of the negative electrode active material to obtain the discharge capacity of the negative electrode active material.

[0146] Similarly, divide the measured discharge capacity for the positive half-cell by the mass of the positive electrode to obtain the discharge capacity of the whole positive electrode; divide the obtained capacity of the positive electrode active material by the mass of the positive electrode active material to obtain the discharge capacity of the positive electrode active material.

[0147] Similarly, divide the measured discharge capacity for the full cell by the mass of the positive electrode to obtain the discharge capacity of the positive electrode sheet (discharge capacity).

[0148] In the above test, the first discharge capacity is divided by the first charge capacity, and then multiplied by 100% to obtain the first coulombic efficiency.

[0149] In the above test, the percentage of the remaining capacity of the nth cycle is the charge capacity at the nth cycle divided by the first charge capacity, and then multiplied by 100%.

[0150] 5.3.2 Sodium-ion secondary battery charge-discharge test

[0151] The charge-discharge test conditions of the assembled battery are as follows: at a temperature of 30°C, the battery is charged to 4V at a current of 0.5C rate, then rested for 5min, then discharged to 2V at a current of 0.5C, then rested for 5min, which is one charge-discharge cycle. The discharge capacity and charge capacity at the first charge-discharge cycle are recorded as the first discharge capacity and the first charge capacity.

[0152] 5.4 Supercapacitor capacitance test

[0153] The capacitance of the supercapacitor is tested according to the national standard GBT34870.1-2017.

[0154] II. Examples

[0155] Example 1: Effect of the addition of non-fibrillated binder on the processing molding

[0156] NCM523, conductive carbon black (TIMCAL Super P Li, same below), polytetrafluoroethylene (Chemours 601X, same below) (fibrillated binder), sodium carboxymethyl cellulose (DAICEL CMC2200, same below) (non-fibrillated binder) were mixed in a mass ratio of 85:5:5:5, and ball-milled (ball-milling conditions: zirconium oxide grinding balls, volume ratio less than 30%, unless otherwise specified, the ball-milling conditions in other examples are the same as this) at a speed of 100 rpm for 30 min to mix uniformly. The obtained mixture after ball-milling was in a flocculent or muddy state. Then, the mixture was roll-extruded (pressure 500 kgf / cm 2 ) at 180°C until the thickness was 80μm, and was named as positive electrode film 21.

[0157] The positive electrode film 22 did not use non-fibrillated binder, i.e., the ratio of NCM523, conductive carbon black, and polytetrafluoroethylene was 85:5:10, and the other preparation processes were consistent with those of the positive electrode film 21.

[0158] As shown in FIGS. 1 and 2, in the absence of non-fibrillated binder, the positive electrode particles were agglomerated and broken under pressure, resulting in a hard and brittle surface of the electrode film with cracks, which may be because the non-fibrillated binder is beneficial to relieve stress during roll pressing.

[0159] Example 2: Effect of non-fibrillated binder addition on electrochemical performance

[0160] Graphite (S360-L2-H), conductive carbon black (TIMCAL Super P Li), polytetrafluoroethylene (MSK-F104) (fibrillated binder), polyvinylidene fluoride (HSV900) (non-fibrillated binder) were mixed in a mass ratio of 85:5:5:5 and ball-milled at 300 rpm for 30 min to mix uniformly. The resulting mixture was in a flocculent or muddy form. The mixture was then roll-pressed at 180 °C (pressure 800 kgf / cm 2 ) until the thickness was 60 pm, and named as negative electrode sheet 1.

[0161] Negative electrode sheet 2 did not use non-fibrillated binder, i.e. the ratio was graphite: conductive carbon black: polytetrafluoroethylene = 85:5:10, and the other preparation processes were consistent with negative electrode sheet 1.

[0162] A 2 pm thick copper metal layer was deposited on the surface of each of the two negative electrode sheets by magnetron sputtering, thereby obtaining negative electrode 1 and negative electrode 2, respectively. The magnetron sputtering conditions were: substrate temperature 30 °C, substrate rotation speed 0 rpm, target-substrate distance 80 mm; main chamber vacuum degree 8 x 10 -4 Pa, process gas (argon) pressure 0.5 Pa, power supply power 120 W, sputtering time 2500 s.

[0163] After the copper metal layer was deposited, slicing and vacuum drying were performed. Then, the negative electrodes were transferred to a glove box and assembled into CR2032 button half-cells in an argon atmosphere. The counter electrode was a lithium sheet with a thickness of 450 pm, and the electrolyte was a 50 pL solution of 1 M LiPF6in ethylene carbonate (EC): diethyl carbonate (DEC) = 1 : 1 (by total volume fraction of EC+DEC, with 10% fluoroethylene carbonate (FEC) and 1% vinylene carbonate (VC) added). The separator was Celgard 2500, with a thickness of 30 pm.

[0164] As shown in Figure 3, in the voltage range of 0.4-0.9 V, the reduction peak of negative electrode 2 (from the irreversible decomposition of polytetrafluoroethylene) was particularly prominent, in contrast, negative electrode 1 showed significantly reduced electrode side reactions in the presence of non-fibrillated binder.

[0165] Figure 4 describes the constant current first charge-discharge curves of the CR2032 button half-cells assembled from negative electrode 1 and negative electrode 2 prepared in Example 2. Compared with negative electrode 2, negative electrode 1 improved the first coulombic efficiency from 68% to 80%.

[0166] Example 3: Effect of fibrillated binder addition sequence

[0167] Silicon-carbon (Timrex® 950K): Conductive carbon black (TIMCAL C45): Polytetrafluoroethylene (MSK-F104) (fibrillated binder): Sodium alginate (Timiron®) (non-fibrillated binder) were mixed in a mass ratio of 93:2:2.5:2.5 to prepare negative electrode sheet 3, negative electrode sheet 4 and negative electrode sheet 5.

[0168] Negative electrode sheet 3 was prepared by mixing silicon-carbon, conductive carbon black and sodium alginate at 8000 rpm for 30 min, and then adding polytetrafluoroethylene again. The mixture was flocculent or muddy. Negative electrode sheet 4 was prepared by mixing silicon-carbon, conductive carbon black, polytetrafluoroethylene and sodium alginate at 8000 rpm for 30 min. The mixture was flocculent or muddy. Negative electrode sheet 5 was prepared by mixing silicon-carbon, conductive carbon black and polytetrafluoroethylene at 8000 rpm for 30 min, and then adding sodium alginate again. The mixture was flocculent or muddy.

[0169] The formation of negative electrode sheet 3, negative electrode sheet 4 and negative electrode sheet 5, and the subsequent magnetron sputtering and half-cell assembly were the same as in Example 2. The first coulombic efficiency and discharge specific capacity of the half-cells corresponding to negative electrode sheet 3, negative electrode sheet 4 and negative electrode sheet 5 are summarized in Table 1.

[0170] Table 1 Electrochemical performance of half-cells corresponding to negative electrode sheets 3-5

[0171] As can be seen from Table 1, the later the order of adding the fibrillated binder such as polytetrafluoroethylene in the mixing process, the better the electrochemical performance of the corresponding electrode. Without wishing to be bound by any theory, this can be because the fibrillation process of the fibrillated binder such as polytetrafluoroethylene hinders the uniform dispersion of the particles.

[0172] Example 4: Effect of heat treatment of electrode sheet

[0173] Graphite (BTR-918): Ketjen black (EC 600JD): Polyacrylic acid (LA133) (non-fibrillated binder): Polytetrafluoroethylene (MSK-F104) (fibrillated binder) were mixed in a mass ratio of 80:10:5:5 and uniformly dispersed by airflow milling (process gas: compressed air, air pressure: 0.3 MPa, room temperature, same below) for 1 h. The mixture was flocculent or muddy. Then, negative electrode sheet 6 and negative electrode sheet 7 were prepared by roll extrusion (pressure 100 kgf / cm 2 ) at room temperature until the thickness was 100 μm. In addition, negative electrode sheet 6 was further stored in vacuum at 180 °C for 12 h and then naturally cooled down; negative electrode sheet 7 was not treated. The formation of negative electrode sheet 6 and negative electrode sheet 7 (thus negative electrode 6 and negative electrode 7), and the subsequent magnetron sputtering and half-cell assembly were the same as in Example 2.

[0174] Figure 5 is a plot showing the heat flow curve of the anode film 6 prepared in Example 4. In Figure 5, the heat flow of the anode film 6 first decreases with increasing temperature, reaches a minimum at about 165 °C, then rapidly increases and tends to be stable. This indicates that the non-fibrillated binder undergoes a phase transition from an initial powder state to a hot melt. Upon cooling, it re-solidifies and binds the electrode material particles together.

[0175] Figure 6 shows the constant current first charge-discharge curves of CR2032 button half-cells assembled with the anodes 6 and 7 prepared in Example 4, respectively. In the case of the anode film subjected to heat treatment before magnetron sputtering, the electrode side reactions are significantly reduced.

[0176] Figure 7 shows the comparison of the first coulombic efficiency of CR2032 button half-cells assembled with the anodes 6 and 7 prepared in Example 4, respectively. The anode 6 improves the first coulombic efficiency from about 70% to about 83% compared to the anode 7.

[0177] Example 5: Interfacial adhesion and impedance

[0178] Lithium manganese iron phosphate (LiFeMnPO4), carbon nanotubes (CNT-3213), sodium alginate (Kelco), polytetrafluoroethylene (Chemours 601X) were mixed in a mass ratio of 86:4:7:3 and dispersed for 60 min using an air jet mill (as above), and the resulting mixture was in a flocculent or muddy state. The anode film was then rolled (1 x 10 3 kgf / cm 2 ) to a thickness of 150 pm at 150 °C to obtain an anode film.

[0179] The obtained anode film was laminated with a commercial carbon-coated aluminum foil (MTI, 15 pm aluminum + 1 pm carbon coating) using a hot press (180 °C, 200 kg) to obtain an anode 26; the obtained anode film was deposited with an ultrathin aluminum current collector (current collector thickness 1.5 pm) using magnetron sputtering to obtain an anode 27. The magnetron sputtering conditions were: substrate temperature 25 °C, substrate rotation speed 20 rpm, target-substrate distance 85 mm, main chamber vacuum degree 3 x 10 -5 Pa, argon gas pressure 1.2 Pa, sputtering power 70 W, sputtering time 50 min. The substrate temperature during magnetron sputtering of the anode 28 was 150 °C, and the other conditions were the same as those of the anode 27.

[0180] The peel strength between the anode film and the corresponding current collector in the anodes 26-28 was then tested, and the results are summarized in Table 2.

[0181] Table 2 Peel strength test results of anode current collectors

[0182] As can be seen from Table 2, the peel force of the positive electrode film to the current collector is greater in the positive electrode prepared by physical deposition such as magnetron sputtering than in the positive electrode 26 prepared by laminating the positive electrode film to the commercial carbon-coated aluminum foil. In addition, the peel force of the positive electrode 28 prepared by sputtering at a substrate temperature of 150°C is greater than that of the positive electrode 27 prepared by sputtering at a substrate temperature of 25°C.

[0183] The prepared electrodes were assembled into CR2032 button half-cells in the manner described in Example 6, and then subjected to impedance tests.

[0184] Fig. 8 is a graph showing the electrochemical impedance (ohm) spectra of the positive electrode 26, the positive electrode 27, and the positive electrode 28, respectively, prepared according to Example 5. As can be seen from Fig. 8, the positive electrodes 27 and 28 prepared by depositing the current collector by physical deposition such as magnetron sputtering have lower impedance than the positive electrode 26 prepared by laminating the positive electrode film to the commercial carbon-coated aluminum foil, and in particular, the positive electrode 28 has lower impedance than the positive electrode 27.

[0185] Example 6: Specific capacity and capacity retention ratio

[0186] The preparation process of the dry electrode was as follows:

[0187] The components were mixed in a mass ratio of graphite (MS-QCG-X) : Ketjen black (EC-300J) : sodium carboxymethyl cellulose (DAICEL CMC2200) : polytetrafluoroethylene (MSK-F104) = 80 : 10 : 6 : 4, and dispersed for 4 h at 5000 rpm using a high-speed shearing machine, and the obtained mixture was in a flocculent or muddy state. Then, the mixture was roll-pressed (800 kgf / cm 2 ) at 180°C to a thickness of 70 μm, and then vacuum stored at 180°C for 16 h and naturally cooled to room temperature, to obtain a negative electrode film.

[0188] The obtained negative electrode film was hot-pressed (180°C, 200 kgf / cm 2 ) to a commercial carbon-coated copper foil (MTI, 12 μm copper + 1 μm carbon coating) to obtain a negative electrode 11; and a 1 μm thick copper and aluminum current collector was deposited on the obtained negative electrode film by magnetron sputtering to obtain a negative electrode 12. The magnetron sputtering conditions were as follows: substrate temperature 150°C, substrate rotation speed 5 rpm, target-to-substrate distance 145 mm, main chamber vacuum degree 8 x 10 -6 Pa, argon gas pressure 0.5 Pa, sputtering power 150 W, and sputtering time 75 min.

[0189] The components were mixed according to the mass ratio of NCM523 (T52S): Ketjenblack (EC-300J): Sodium carboxymethyl cellulose (DAICEL CMC2200): Polytetrafluoroethylene (MSK-F104) = 80:10:6:4. The mixture was dispersed at 5000 rpm for 4 hours using a high-speed shear press, resulting in a flocculent or mud-like consistency. Then, it was rolled at 180°C (600 kgf / cm³). 2 The thickness was increased to 100 μm, and then the film was vacuum preserved at 180 °C for 16 h and then naturally cooled to room temperature to obtain the positive electrode film.

[0190] The obtained positive electrode film was hot-pressed and laminated with commercial carbon-coated aluminum foil (MTI, 20 μm aluminum + 1 μm carbon coating) at 180 °C and 200 kgf / cm². 2 A positive electrode 29 was obtained; an aluminum current collector with a thickness of 1 μm was deposited on the obtained positive electrode film by magnetron sputtering to obtain positive electrode 30. The magnetron sputtering conditions were: substrate temperature 150℃, substrate rotation speed 5 rpm, target-substrate distance 145 mm, and main cavity vacuum degree 8 × 10⁻⁶. -6 Pa, argon gas pressure 0.5 Pa, sputtering power 150 W, sputtering time 75 min.

[0191] The preparation process of the wet electrode is as follows:

[0192] The wet anode was prepared as follows: Graphite (MS-QCG-X): Ketjen black (EC-300J): polyvinylidene fluoride (SHV900) = 80:10:10 (maintaining the same binder ratio as anodes 11 and 12). The material was dispersed in NMP with a solid content of 50%. The mixture was ball-milled at 300 rpm for 30 min to form a uniform, fluid slurry. The slurry was then uniformly coated onto copper foil using a doctor blade and vacuum dried to obtain the wet anode (i.e., wet graphite@commercial copper).

[0193] The wet cathode was prepared as follows: The materials were dispersed in NMP with a solid content of 40% using a mass ratio of NCM523 (T52S): Ketjen Black (EC-300J): polyvinylidene fluoride (SHV900) of 80:10:10 (maintaining the same binder ratio as cathodes 29 and 30). The mixture was ball-milled at 500 rpm for 40 minutes to form a uniform, fluid slurry. The slurry was then evenly coated onto aluminum foil using a scraper and vacuum dried to obtain the wet cathode (i.e., wet NCM523@commercial aluminum).

[0194] The dry and wet negative electrodes prepared above were assembled into a CR2032 button cell according to the method in Example 2.

[0195] A positive CR2032 button half-cell was fabricated in a similar way as the negative CR2032 button half-cell, except that the dry and wet positive electrodes prepared above were used as the working electrode instead of the dry and wet negative electrodes prepared above, and lithium metal was used as the counter electrode.

[0196] The discharge specific capacity of the electrode active material and the discharge specific capacity of the electrode as a whole corresponding to the half-cells of the negative 11-12 and positive 29-30 were measured respectively. Fig. 9 presents the discharge specific capacity test results of the negative half-cell corresponding to the negative 11-12, and Fig. 10 presents the discharge specific capacity test results of the positive half-cell corresponding to the positive 29-30 at different rates.

[0197] As can be seen from Figs. 9-10, under the same conditions, the electrode active material and the electrode as a whole have higher discharge specific capacity (including the first discharge specific capacity and the cyclic discharge specific capacity) in the electrode prepared by the method of the present application than in the electrode prepared by hot pressing the dry electrode film and the commercial current collector. This is conducive to improving the energy density of the energy storage device and improving the cycle performance of the energy storage device.

[0198] In addition, the inventors also studied the cyclic discharge specific capacity of the electrode at different rates. Referring to Fig. 10, even if the charge and discharge rate is changed, the electrode prepared by the method of the present application still has higher cyclic discharge specific capacity of the electrode active material and the cyclic discharge specific capacity of the electrode as a whole than the electrode prepared by hot pressing the dry electrode film and the commercial current collector, which indicates that the energy storage device such as a secondary battery using the electrode prepared by the preparation method of the present application also has improved rate performance.

[0199] Further, the inventors also replaced the positive active material with lithium iron phosphate, lithium cobaltate, NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2) prepared by different methods respectively, and replaced the negative active material with silicon-carbon material prepared by different methods respectively, and prepared the positive or negative electrode in the same way (except that the active material was different, other conditions were the same). Then, the active material discharge specific capacity of the prepared positive and negative electrode sheets, the positive electrode discharge specific capacity and the capacity remaining ratio of the electrode were measured, and the test results are summarized in Table 3.

[0200] Table 3: Specific capacity and capacity remaining ratio of different electrodes after 100 cycles * “Dry method” means that the electrode active material, the conductive additive, the non-fibrillated binder and the fibrillated binder are made into an electrode in the method of the present application; **The "wet method" refers to an electrode prepared by uniformly dispersing an electrode active material, a conductive additive, and a binder in a solvent to form a slurry having a certain fluidity, and then coating the electrode slurry on a metal foil current collector and drying to prepare an electrode; *** The active material specific capacity and the electrode overall specific capacity in Table 3 were measured at 0.5C rate.

[0201] As can be seen from Table 3, when different electrode active materials were tested, the electrodes prepared by the dry electrode film of the present application and the magnetron sputtering current collector both had higher overall cyclic discharge specific capacity of the electrode, and the specific capacity of the active material was significantly improved, compared to the wet electrode film and the electrode prepared by hot pressing the dry electrode film and the commercial current collector.

[0202] In addition, the secondary battery including the electrode prepared by the method of the present application had a higher capacity remaining ratio after 100 cycles, indicating that the life characteristics of the secondary battery were improved.

[0203] Example 7: Secondary battery cyclic discharge specific capacity and energy density

[0204] The negative electrode 14 and the positive electrode 32 were prepared in the same manner as the negative electrode 11 and the positive electrode 29 (both using a commercial carbon-coated current collector) in Example 6, and the negative electrode 15 and the positive electrode 33 were prepared in the same manner as the negative electrode 12 and the positive electrode 30 (both using a magnetron sputtering deposited current collector) in Example 6. Then, the negative electrode 14 and the positive electrode 32, and the negative electrode 15 and the positive electrode 33 were assembled into secondary batteries with a negative electrode capacity to positive electrode capacity ratio (N / P ratio) = 1.15, respectively. The separator and the electrolyte used in the secondary batteries were the same as in Example 2.

[0205] FIG. 11 presents a graph of the overall discharge specific capacity of the secondary battery using a commercial current collector and the secondary battery using a magnetron sputtering current collector versus the cycle number. As can be seen from FIG. 11, the secondary battery using the magnetron sputtering current collector had a higher cyclic discharge specific capacity. This indicates that the energy storage device such as the secondary battery prepared by the method of the present application has improved cycle performance.

[0206] FIG. 12 presents a graph of the charge-discharge voltage versus the overall discharge specific capacity of the secondary battery for the first charge-discharge cycle of the secondary battery using a commercial current collector and the secondary battery using a magnetron sputtering current collector. As can be seen from FIG. 12, the secondary battery using the magnetron sputtering current collector can provide a higher discharge specific capacity under the same electrochemical window.

[0207] The inventors further changed the type of electrode active material, prepared other secondary batteries under the same conditions, and tested the energy density of these secondary batteries. The test results are summarized in Table 4.

[0208] Table 4 Energy density test results

[0209] As can be seen from Table 4, the secondary battery using the magnetron sputtering current collector has a higher energy density than the secondary battery using the commercial current collector.

[0210] Example 8: Supercapacitor

[0211] The activated carbon: Ketjen black: polyvinylidene fluoride: polytetrafluoroethylene were mixed in a mass ratio of 90:5:1:4, and dispersed for 0.5 h with an airflow mill to mix uniformly, and the obtained mixture was flocculated or muddy, and then rolled (pressure 500 kgf / cm 2 , 160°C) to a thickness of 100 μm to obtain an electrode film.

[0212] Two of the obtained electrode films were laminated with a commercial carbon-coated 20 μm aluminum foil by hot pressing (temperature 180°C, pressure 200 kgf / cm 2 ) to serve as positive and negative electrodes (combination 1, i.e., activated carbon | commercial aluminum foil).

[0213] In addition, two of the obtained electrode films were each deposited with 1 μm of aluminum current collector by magnetron sputtering, and the magnetron sputtering conditions were: substrate temperature 100°C, substrate rotation speed 5 rpm, target-substrate distance 65 mm, main cavity vacuum degree 8 x 10 -4 Pa, argon gas pressure 0.5 Pa, sputtering power 150 W, and sputtering time 15 min. The obtained electrodes were used as positive and negative electrodes (combination 2, i.e., activated carbon | magnetron aluminum).

[0214] The above-prepared positive and negative electrodes combination 1 and 2 (i.e., activated carbon | commercial aluminum foil and activated carbon | magnetron aluminum) were each assembled into a capacitor, which was a structure-symmetrical capacitor. The electrolyte used was 6M KOH aqueous solution.

[0215] Some parameters of the activated carbon electrode are summarized in Table 5.

[0216] Table 5 Parameters of activated carbon electrode (under the same active material loading)

[0217] Table 6 Performance of activated carbon supercapacitor (under the same active material loading)

[0218] As can be seen from Tables 5-6, compared with the capacitor prepared by combination 1 (i.e., activated carbon | commercial aluminum foil), the supercapacitor prepared by the method of the present application has a significantly higher proportion of active material, and the electrode active material also unexpectedly has a higher specific capacitance, so that the supercapacitor prepared by the method of the present application has a significantly higher overall specific capacitance and energy density.

[0219] Example 9: Sodium-ion secondary battery

[0220] Hard carbon: conductive carbon black: carboxymethyl cellulose sodium: polytetrafluoroethylene were mixed in a mass ratio of 90:4:3:3, and the resulting mixture was dispersed with an air jet mill for 0.5 h. The resulting mixture was in the form of a flocculent or muddy mass. The resulting flocculent or muddy mass was then roll-pressed at 180°C (pressure 800 kgf / cm 2 ) to a thickness of 100 μm to obtain a negative electrode film.

[0221] Prussian blue (Na2FeFe(CN)6(NaHCF)): conductive carbon black: carboxymethyl cellulose sodium: polytetrafluoroethylene were mixed in a mass ratio of 90:4:3:3, and then dispersed with an air jet mill (conditions as above) for 0.5 h. The resulting mixture was in the form of a flocculent or muddy mass. The resulting flocculent or muddy mass was then roll-pressed at 180°C (pressure 600 kgf / cm 2 ) to a thickness of 100 μm to obtain a positive electrode film.

[0222] The negative electrode film and the positive electrode film were vacuum-stored at 150°C for 24 h, and then naturally cooled to room temperature.

[0223] The resulting positive electrode film and negative electrode film were each hot-pressed with a commercial carbon-coated 20 μm aluminum foil to obtain a commercial aluminum foil positive electrode and a commercial aluminum foil negative electrode. The resulting positive electrode film and negative electrode film were each sputter-deposited with 1 μm of an aluminum current collector under the following conditions: substrate temperature 150°C, substrate rotation speed 5 rpm, target-to-substrate distance 80 mm, main chamber vacuum degree 8 x 10 -6 Pa, argon gas pressure 0.5 Pa, sputtering power 80 W, sputtering time 20 min, to obtain a sputter-deposited positive electrode and a sputter-deposited negative electrode.

[0224] Separator: Celgard 2325, thickness 30 μm;

[0225] Electrolyte: 1 M NaPF6 solution in DME (100% by volume).

[0226] The resulting positive and negative electrodes were assembled with a separator and an electrolyte to obtain a sodium-ion secondary battery (N / P ratio = 1.15).

[0227] Table 7 Summary of partial parameters of sodium-ion secondary batteries (under the same active material load)

[0228] Table 8 Comparison of performance of sodium-ion batteries

[0229] As can be seen from Tables 7-8, compared with the sodium-ion secondary battery prepared by compounding with commercial aluminum foil, the sodium-ion secondary battery prepared by the method of the present application is more compact and light, and the electrode active material also unexpectedly has higher specific capacity, so that the sodium-ion secondary battery prepared by the method of the present application has significantly higher energy density.

[0230] Example 10: deposition of current collector by evaporation method

[0231] NCM523: Ketjen black: sodium carboxymethyl cellulose: polytetrafluoroethylene were dispersed by a high-speed shearing machine at 5000 rpm for 4 h at a mass ratio of 80:10:6:4, and the obtained mixture was in a flocculent or muddy state. Then the flocculent or muddy product was rolled at 180°C to a thickness of 100 μm to obtain a positive electrode film. The obtained positive electrode film was stored in vacuum at 180°C for 16 h and naturally cooled to room temperature. Then an aluminum layer with a thickness of 1 μm was deposited on the surface of the cooled positive electrode film by vacuum evaporation, and the evaporation conditions were: evaporation temperature 680°C, vacuum degree 10 -2 Pa, and evaporation time 15 min.

[0232] The above description is only an exemplary embodiment of the present application. It should be noted that those skilled in the art can make improvements to the present application without departing from the inventive concept, and these all belong to the protection scope of the present application.

Claims

1. A method of making an electrode, comprising: (1) making an electrode sheet, comprising: (a) mixing mixing an electrode active material, a conductive additive, a non-fibrillated binder homogeneously, then adding a fibrillated binder, and processing the resulting mixture into a flocculent or a mud; or mixing an electrode active material, a conductive additive, a non-fibrillated binder, and a fibrillated binder homogeneously, and processing the resulting mixture into a flocculent or a mud; (b) shaping shaping the flocculent or mud product from step (a) into an electrode sheet; (2) depositing a current collector, comprising: depositing a metal layer as a current collector on one surface of the electrode sheet from step (1) by a physical deposition method.

2. The method of making an electrode according to claim 1, wherein step (1) further comprises, after making the electrode sheet, holding the resulting electrode sheet at a temperature of 100-250°C, preferably 150-200°C, preferably in vacuum, for 4-20h, preferably 8-16h.

3. The method of making an electrode according to claim 1 or 2, wherein the physical deposition method is selected from one or more of sputter plating (e.g. magnetron sputtering), evaporation plating, or ion plating. Preferably, the physical deposition method is magnetron sputtering, and the process conditions are as follows: substrate temperature is 10-300°C, preferably 20-200°C, substrate rotation speed is 0-20 rpm, target-substrate distance is 50-200 mm; main chamber vacuum is 5x10 -3 Pa, process gas pressure is 0.5-15 Pa, power supply power is 20-500 W, and sputtering time is 20-5000 s. -6 Pa, process gas pressure is 0.5-15 Pa, power supply power is 20-500 W, and sputtering time is 20-5000 s.

4. The method of making an electrode according to any one of claims 1-3, wherein one or more of the following conditions are met: i. the mixing in step (a) is carried out by one or more of ball milling, jet milling, high speed shear, or mechanical milling; ii. forming the flocculent or muddy product obtained in step (a) into an electrode film by one or more of the following: roll-pressing (e.g. hot roll forming), extrusion forming, injection forming, blow forming, coating forming, or casting forming, preferably roll-pressing (e.g. hot roll forming), extrusion forming, preferably under the following roll-pressing conditions: roll-pressing temperature of 10-200°C, roll-pressing pressure of 0.1 x 10 3 -20.0 x 10 3 kgf / cm 2 , roll-pressing speed of 0.5-50 m / min, and roll-pressing number of 1-30 times; iii. step (2) comprises depositing a patterned metal layer as a current collector on the one surface of the electrode sheet from (1); iv. step (2) comprises, prior to depositing the metal layer, subjecting the electrode sheet to a pre-treatment step selected from one or more of plasma cleaning and surface etching; preferably, the process gas for the plasma cleaning is selected from one or more of oxygen, helium, argon, or xenon: preferably, the time for the surface etching is 1-10min; or v. there is no pre-shaping step prior to step (b).

5. The method of making an electrode according to any one of claims 1-4, wherein one or more of the following conditions are met: vi. the non-fibrillated binder is selected from one or more of polyvinylidene fluoride, sodium carboxymethylcellulose, polyacrylic acid, polyvinyl alcohol, sodium alginate, poly(ethylene oxide), polyacrylonitrile (PAN), polyimide (PI), cellulose and cellulose derivatives (e.g. cellulose acetate, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), nitrocellulose, carboxymethyl cellulose (CMC), carboxyethyl cellulose, carboxypropyl cellulose, carboxyisopropyl cellulose, sodium cellulose, sodium nitrate cellulose, and sodium carboxyalkyl cellulose), preferably one or more of polyvinylidene fluoride, sodium carboxymethylcellulose, polyacrylic acid, sodium alginate; vii. the fibrillated binder is selected from polytetrafluoroethylene; viii. the weight ratio of the amount of the fibrillated binder added to the amount of the non-fibrillated binder, based on the dry weight of the electrode sheet, is 0.1:1 to 10:1, preferably 0.1:1 to 3.0:

1. ix. the amount of the fibrillated binder is 0.5-10 wt.%, preferably 1-5 wt.% based on the dry weight of the electrode sheet; x. the amount of the non-fibrillated binder is 0.5-10 wt.%, preferably 1-8 wt.% based on the dry weight of the electrode sheet; or xi. the total amount of the non-fibrillated binder and the fibrillated binder is 1-15 wt.%, for example 1-10 wt.% based on the dry weight of the electrode sheet.

6. The electrode preparation method according to any one of claims 1-5, wherein the electrically conductive additive is selected from one or more of graphite, super-P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, preferably, the amount of the electrically conductive additive is 0.5-10 wt.% based on the dry weight of the electrode sheet.

7. The electrode preparation method according to any one of claims 1-6, wherein one or more of the following conditions is met: xii. the ratio of the thickness of the current collector to the thickness of the electrode sheet is in the range of 0.0001:1 to 0.1000:1, preferably 0.0050:1 to 0.0300:1; xiii. the thickness of the current collector is 0.1-10 pm, preferably 0.5-2 pm; or xiv. the thickness of the electrode sheet is 10-1000 pm, preferably 50-200 pm.

8. An electrode prepared according to the electrode preparation method of any one of claims 1-7.

9. An energy storage device comprising a positive electrode and a negative electrode, wherein at least one of the positive electrode and the negative electrode, preferably both the positive electrode and the negative electrode, comprises the electrode of claim 8.

10. The energy storage device of claim 9, wherein the energy storage device is a lithium-ion secondary battery, a sodium-ion secondary battery, a lithium-sulfur secondary battery, or a capacitor, a supercapacitor, a lithium-ion capacitor, preferably a lithium-ion secondary battery, a sodium-ion secondary battery; the negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon-based materials, tin-based materials, lithium titanate, and metallic lithium, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composite, and silicon alloy, preferably, the amount of the negative electrode active material is 80-98 wt.%, preferably 90-98 wt.% based on the dry weight of the negative electrode sheet; wherein when the energy storage device is a lithium ion secondary battery, the positive active material is selected from one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-containing phosphate of olivine structure, preferably LiFeMnPO4, LiCoO2, LiMn2O4, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, and LiFePO4, preferably the amount of the positive active material is 80-98 wt.%, preferably 90-98 wt.%, based on the dry weight of the positive electrode film, and / or the negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon-based materials, and tin-based materials, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composite, and silicon alloy, preferably, the amount of the negative electrode active material is 80-98 wt.%, preferably 90-98 wt.% based on the dry weight of the negative electrode sheet; When the energy storage device is a sodium-ion secondary battery, the positive active material is selected from one or more of a layered transition metal oxide or a Prussian blue analogue, preferably Na2FeFe(CN)6(NaHCF), NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, Na2FeP2O7, Na4Fe3(PO4)2(P2O7), Na3V2(PO4)3, NaFePO4, and NaMnFe(CN)6, preferably in an amount of 80-98 wt.%, preferably 90-98 wt.%, based on the dry weight of the positive electrode film, and / or the negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon-based materials, and tin-based materials, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composite, and silicon alloy, preferably, the amount of the negative electrode active material is 80-98 wt.%, preferably 90-98 wt.% based on the dry weight of the negative electrode sheet; When the energy storage device is a lithium-sulfur secondary battery, the positive active material is selected from one or more of lithium sulfide, titanium sulfide, phosphorus sulfide, or an organic compound having a linear alkyl group, a branched alkyl group, a cycloalkane, an arene, a heteroatom-containing arene, or a compound in which sulfur is combined with a compound having a linear alkyl group, a branched alkyl group, a cycloalkane, an arene, a heteroatom-containing arene, preferably one or more of a sulfur-carbon composite positive electrode material and a sulfurized polyacrylonitrile, preferably, the amount of the positive active material is 80-98% by weight, preferably 90-98% by weight, based on the dry weight of the positive electrode sheet, and / or the negative active material is selected from metal lithium, preferably, the amount of the negative active material is 80-99% by weight, preferably 90-99% by weight, based on the dry weight of the negative electrode sheet; When the energy storage device is a capacitor, the positive active material is selected from one or more of a metal oxide, an electrically conductive polymer, and a carbon material, preferably one or more of MnO2, NiO, Co3O4, polyaniline, polypyrrole, activated carbon, graphene, and biochar, preferably, the amount of the positive active material is 80-98% by weight, preferably 90-98% by weight, based on the dry weight of the positive electrode sheet, and / or the negative active material is selected from one or more of a metal, a carbon material, an electrically conductive polymer, a metal oxide, a metal-organic framework (MOF) derived material, preferably one or more of aluminum, zinc, activated carbon, graphite, polyaniline, polypyrrole, polythiophene, and MnO2, preferably, the amount of the negative active material is 80-98% by weight, preferably 90-98% by weight, based on the dry weight of the negative electrode sheet.

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