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

Abstract

The invention relates to an electrode preparation method, an electrode prepared by the electrode preparation method and an energy storage device comprising the electrode, and the preparation method comprises the following steps: (1) preparing an electrode diaphragm: (a) mixing materials: uniformly mixing an electrode active material, a conductive additive and a non-fibrillated binder, then adding a fibrillated binder, and uniformly mixing the materials to obtain the electrode diaphragm; processing the obtained mixture to be flocculent or muddy; or uniformly mixing the electrode active material, the conductive additive, the non-fibrillated binder and the fibrillated binder, and processing the obtained mixture to be flocculent or muddy; (b) forming: forming the flocculent or muddy product obtained in the step (a) into an electrode membrane; and (2) depositing a current collector: depositing a metal layer on one surface of the electrode diaphragm obtained in the step (1) through a physical deposition method to serve as the current collector. The energy storage device provided by the invention has improved cycle performance, rate capability and first coulombic efficiency.

Description

Technical Field

[0001] The present invention generally relates to the field of electrochemistry, particularly to the field of energy storage. Specifically, the present invention relates to a method for preparing an electrode, an electrode obtained by the method, and an energy storage device including the electrode, such as a lithium-ion secondary battery, a sodium-ion secondary battery, a lithium-sulfur secondary battery, or a capacitor. Background Art

[0002] The electrode is an important component of an electrochemical energy storage device such as a secondary battery, and its specific capacity and working voltage have a great impact on the energy of the electrochemical device. As the use of energy storage devices in life becomes more and more extensive, the demand for high-performance (such as good cycle performance, rate performance, and high initial Coulomb efficiency) energy storage devices is increasing day by day. Electrodes are generally prepared by mixing active materials and the like with a solvent, coating them on a current collector, and drying. However, the electrodes prepared by the existing technical methods still have problems such as low energy density, poor cycle performance and rate performance, and low initial Coulomb efficiency, and it is difficult to meet the growing needs of people.

[0003] In view of the above problems, those skilled in the art still need to develop a new method for preparing an electrode. Compared with the electrodes prepared by traditional preparation methods, the electrodes prepared by this method have good cycle performance (including improved initial discharge specific capacity and cycle discharge specific capacity, which means higher energy density under the same conditions), rate performance, and improved initial Coulomb efficiency. Summary of the Invention

[0004] The present invention is made in view of the above problems existing in the prior art.

[0005] In a first aspect, the present invention relates to a method for preparing an electrode, including:

[0006] (1) Preparing an electrode membrane, including:

[0007] (a) Mixing materials

[0008] Mixing the electrode active material, the conductive additive, and the non-fibrillated binder uniformly, then adding the fibrillated binder, and processing the obtained mixture into a flocculent or muddy state; or

[0009] 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 state;

[0010] (b) Shaping

[0011] Shaping the flocculent or muddy product obtained in step (a) into an electrode membrane;

[0012] (2) Depositing a current collector, including:

[0013] A metal layer is deposited as a current collector on one surface of the electrode film obtained in step (1) by physical deposition method.

[0014] The electrode preparation method of the present invention does not use solvents such as organic solvents, thus overcoming some defects of traditional electrode preparation methods. It avoids using expensive and highly toxic organic solvents such as N-methylpyrrolidone, is environmentally friendly and has cost advantages.

[0015] In addition, compared with electrodes prepared by traditional electrode preparation methods (such as coating electrode active materials on current collectors), after mixing electrode active materials, conductive additives, non-fibrillated cellulose and fibrillated cellulose in the present invention, an electrode film is obtained by forming, and then a current collector is deposited on the obtained electrode film, thereby significantly reducing the volume and mass ratio of the sheet-like current collector used for coating active materials in energy storage devices, and improving the mass specific capacity and volume specific capacity of energy storage devices.

[0016] Furthermore, after extensive research, the inventors surprisingly found that, compared with traditional electrodes obtained by coating positive and negative electrode active materials on positive and negative current collectors, in addition to the increase in specific capacity brought about by the reduction in the mass and volume of auxiliary components, in the electrodes prepared by the method of the present invention, the electrode active materials have improved initial discharge specific capacity and cyclic discharge specific capacity, even at increased charge-discharge rates. This is beneficial to improving the energy density of energy storage devices, and improving the cyclic performance and rate performance of energy storage devices. In addition, compared with traditional electrodes with positive and negative electrode active materials coated on positive and negative current collectors, the energy storage devices including the electrodes prepared by the method of the present invention also have improved initial Coulomb efficiency.

[0017] In addition, the inventors also unexpectedly found that by adjusting the addition sequence of fibrillated binder, the treatment temperature of the electrode film, and / or the temperature of the physical deposition process, etc., the initial Coulomb efficiency or discharge specific capacity can be further improved, and / or the peeling force between the current collector and the electrode film can be increased or the impedance of the electrode sheet can be reduced.

[0018] The electrodes prepared by the electrode preparation method of the first aspect of the present invention have improved cyclic performance (including improved initial discharge specific capacity and cyclic discharge specific capacity) and rate performance, as well as high initial Coulomb efficiency.

[0019] Alternatively or additionally, the electrodes prepared by the electrode preparation method of the first aspect of the present invention have improved peeling force between the current collector and the electrode film.

[0020] Alternatively or additionally, the electrodes prepared by the electrode preparation method of the first aspect of the present invention have reduced impedance.

[0021] In a second aspect, the present invention relates to an electrode prepared by the electrode preparation method according to the first aspect of the present invention.

[0022] In a third aspect, the present invention relates to an energy storage device, which includes 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, includes the electrode according to the second aspect of the present invention.

[0023] The present invention will be described in detail below by way of exemplary embodiments and in conjunction with the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. Description of the Drawings

[0024] To more clearly illustrate the technical solution of the present invention, the accompanying drawings required for describing the embodiments will be briefly described below. It should be understood that these drawings are only for the convenience of those skilled in the art to more easily understand the present invention and are not intended to limit the scope of the present invention.

[0025] Figure 1 Scanning electron microscope picture of the positive electrode film 21 prepared for Example 1.

[0026] Figure 2 Scanning electron microscope picture of the positive electrode film 22 prepared for Example 1.

[0027] Figure 3 Cyclic voltammogram of the CR2032 button half-cell assembled with the negative electrodes 1 and 2 prepared for Example 2.

[0028] Figure 4 Galvanostatic first charge-discharge curve of the CR2032 button half-cell assembled with the negative electrodes 1 and 2 prepared for Example 2.

[0029] Figure 5 Heat flow curve of the negative electrode film 6 prepared for Example 4.

[0030] Figure 6 Galvanostatic first charge-discharge curves of the CR2032 button half-cells assembled with the negative electrodes 6 and 7 prepared for Example 4 are shown.

[0031] Figure 7 Comparison chart of the first Coulombic efficiency of the CR2032 button half-cells assembled with the negative electrodes 6 and 7 prepared for Example 4 is shown.

[0032] Figure 8 Graph showing the electrochemical impedance (ohm) spectra of the positive electrodes 26, 27, and 28 prepared according to Example 5 respectively.

[0033] Figure 9To show the graphs of the discharge specific capacities (mAh / g) of the negative electrode active materials and the entire negative electrodes of the negative electrodes 11 and 12 prepared according to Example 6, respectively, against the number of cycles.

[0034] Figure 10 To show the graphs of the discharge specific capacities (mAh / g) of the positive electrode active materials and the entire positive electrodes of the positive electrodes 29 and 30 prepared according to Example 6, respectively, against the number of cycles at different rates.

[0035] Figure 11 To show the graphs of the discharge specific capacities (mAh / g) of the entire batteries of the secondary batteries 1 and 2 prepared according to Example 7 against the number of cycles.

[0036] Figure 12 To show the graph of the charge-discharge voltage (V) of the first charge-discharge cycle of the secondary batteries 1 and 2 prepared according to Example 7 against the discharge specific capacity (mAh / g) of the entire battery. Detailed implementation manners

[0037] To make the invention 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, implementation manners, and their advantages described in the present application can be compatible and / or combined together.

[0038] Unless otherwise specified, the meanings of the scientific and technical terms in this specification are the same as those generally understood by those skilled in the art.

[0039] The present invention relates to an electrode preparation method, an electrode obtained thereby, and an energy storage device including the electrode, 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.

[0040] The present invention will be specifically described below.

[0041] Electrode preparation method

[0042] In a first aspect, the present invention relates to an electrode preparation method, including:

[0043] (1) Preparing an electrode membrane, including:

[0044] (a) Mixing materials

[0045] Mixing an electrode active material, a conductive additive, and a non-fibrillating binder uniformly, then adding a fibrillating binder, and processing the obtained mixture into a flocculent or muddy state; or

[0046] Mixing an electrode active material, a conductive additive, a non-fibrillating binder, and a fibrillating binder uniformly, and processing the obtained mixture into a flocculent or muddy state;

[0047] (b) Shaping

[0048] Shape the flocculent or muddy product obtained in step (a) into an electrode diaphragm;

[0049] (2) Depositing a current collector, including:

[0050] Deposit a metal layer as a current collector on one surface of the electrode diaphragm obtained in step (1) by physical deposition.

[0051] The electrode preparation method of the present invention does not use solvents such as organic solvents, thus overcoming some defects of traditional electrode preparation methods. It avoids using expensive and highly toxic organic solvents such as N-methylpyrrolidone, is environmentally friendly and has a cost advantage.

[0052] In addition, compared with electrodes prepared by traditional electrode preparation methods (such as coating electrode active materials on current collectors), after mixing electrode active materials, conductive additives, non-fibrillated cellulose and fibrillated cellulose in the present invention, an electrode diaphragm is obtained by shaping, and then a current collector is deposited on the obtained electrode diaphragm, thereby significantly reducing the volume and mass ratio of the sheet-like current collector used for coating active materials in energy storage devices, and improving the mass specific capacity and volume specific capacity of energy storage devices.

[0053] Furthermore, the inventors unexpectedly found after a large number of studies that, compared with traditional electrodes obtained by coating positive and negative electrode active materials on positive and negative current collectors, in addition to the increase in specific capacity brought about by the reduction in the mass and volume of auxiliary components, in the electrodes prepared by the method of the present invention, the electrode active materials have improved first discharge specific capacity and cyclic discharge specific capacity, even at increased charge and discharge rates. This is beneficial to improving the energy density of energy storage devices and improving the cyclic performance and rate performance of energy storage devices. In addition, compared with traditional electrodes obtained by coating positive and negative electrode active materials on positive and negative current collectors, energy storage devices including electrodes prepared by the method of the present invention also have improved first Coulombic efficiency.

[0054] In addition, the inventors also unexpectedly found that by adjusting the addition order of the fibrillated binder, the treatment temperature of the electrode diaphragm, 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 diaphragm can be increased or the impedance of the electrode sheet can be reduced.

[0055] The electrode preparation method of the present invention includes preparing an electrode diaphragm and depositing a current collector. Each step will be introduced in detail below.

[0056] Preparing an electrode diaphragm

[0057] The preparation of electrode membranes includes mixing and molding steps.

[0058] It should be noted that the term "electrode membrane" refers to a membrane (i.e., active material layer) prepared from materials including electrode active materials, conductive additives, binders, etc., which does not include a current collector. In contrast, "electrode" or "electrode sheet" includes not only "electrode membrane" but also "current collector".

[0059] Mixing

[0060] The purpose of the mixing process is to obtain a mixture of electrode active materials, conductive additives, non-fibrillating binders and optional fibrillating binders to facilitate subsequent steps.

[0061] In some embodiments, the mixing process uniformly mixes the electrode active material, the conductive additive, the non-fibrillated binder and the fibrillated binder, and processes the resulting mixture into a flocculent or muddy state.

[0062] The inventors found in their research that the addition of non-fibrillated binders helps to relieve stress during the rolling process, so as to prevent the particles from being pressed and broken, thereby preventing the electrode membrane from being hard and brittle with cracks on the surface. In addition, the inventors unexpectedly found that the addition of non-fibrillated binders can significantly reduce electrode side reactions and improve the first coulombic efficiency.

[0063] Compared with non-fibrillated binders, adding fibrillated binders can carry out a fibrillation process so that the resulting mixture can be processed into a flocculent or muddy state. In this article, the term "fibrillation" refers to the "fibrillated binder" that is originally granular and is stretched into a fiber state under shear force under mechanical action, and entangled with electrode active materials and conductive additives to form a three-dimensional network. The inventors also unexpectedly discovered in the study that during the mixing process, the order of adding the fibrillated binder will have a significant effect on the first coulomb efficiency and discharge specific capacity, such as the first discharge specific capacity. Specifically, during the mixing process, the later the order of adding the fibrillated binder, the higher the first coulomb efficiency and discharge specific capacity, such as the first discharge specific capacity, of the corresponding energy storage device, such as a secondary battery such as a lithium-ion secondary battery.

[0064] Therefore, in a preferred embodiment, the electrode active material, the conductive additive, and the non-fibrillated binder are uniformly mixed in the mixing process, and then the fibrillated binder is added, and the resulting mixture is processed into a flocculent or muddy state.

[0065] It should be noted that the term "fibrillating binder" refers to a binder component that undergoes structural slippage under shear force during the preparation of the electrode film and then extends into a fiber network with a winding and coating function in the electrode structure. In contrast, the term "non-fibrillating binder" refers to a binder component that melts / molten by solvent or heating to form a coating in the electrode and realizes adhesion by using the interaction forces (including van der Waals forces, hydrogen bonds, covalent interactions, etc.) between the binder and each component of the electrode. Therefore, the "fibrillating binder" is different from the "non-fibrillating binder".

[0066] The preparation method of the present invention has no special requirements for the type of non-fibrillating binder, and any type of non-fibrillating binder commonly used in the art can be used. As an example, the non-fibrillating 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 (such as cellulose acetate, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), cellulose nitrate, carboxymethyl cellulose (CMC), carboxyethyl cellulose, carboxypropyl cellulose, carboxyisopropyl cellulose, sodium cellulose, sodium cellulose nitrate and sodium carboxyalkyl cellulose), preferably one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose, polyacrylic acid, sodium alginate.

[0067] Similarly, the preparation method of the present invention has no special requirements for the type of fibrillating binder, and any type of fibrillating binder commonly used in the art can be used. As an example, the fibrillating binder is selected from polytetrafluoroethylene. Preferably, the volume average particle size D v 50 is in the range of 0.1 - 1000 μm, preferably 200 - 600 μm. D v 50 particle size means that in the volume cumulative distribution curve of particles (such as fibrillating binder), the particles smaller and larger than this particle size value each account for 50% of the total sample volume. The D v 50 particle size of particles (such as fibrillating binder) can be measured by methods commonly used by those skilled in the art. As an example, laser diffraction method can be used to measure with a laser particle size analyzer.

[0068] Similarly, the preparation method of the present invention has no special requirements for the type of conductive additive, and conductive additives 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.

[0069] Those skilled in the art can easily understand that, in addition to the electrode active material, conductive additive, non-fibrillated binder, and fibrillated binder, other common substances for electrode preparation, such as thickeners, film-forming promoters, etc., can also be added during the mixing process.

[0070] In some embodiments, based on the total weight of all components for mixing, the weight ratio of the addition amount of the fibrillated binder to the addition amount of the non-fibrillated binder is from 0.1:1 to 10:1, preferably from 0.1:1 to 3.0:1, 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 within the range defined by any two of them. When the weight ratio of the addition amount of the fibrillated binder to the addition amount of the non-fibrillated binder is within the above range, it is beneficial for the fibrillated binder and the non-fibrillated binder to better play a synergistic effect, thereby being beneficial to improving the cycle performance (including the first discharge capacity and the cycle discharge capacity), rate performance, and first Coulomb efficiency.

[0071] In some embodiments, based on the total weight of all components for mixing, the addition amount of the electrode active material is 80-98% by weight, preferably 90-98% by weight; the addition amount of the conductive additive is 0.5-10% by weight; the addition amount of the non-fibrillated binder is 0.5-10% by weight, preferably 1-8% by weight; the addition amount of the fibrillated binder is 0.5-10% by weight, preferably 1-5% by weight. It is easy for those skilled in the art to understand that the total weight of all components for mixing is 100%. As an example, based on the total weight of all components for mixing, the addition amount of the fibrillated binder can be 0.5% by weight, 1.0% by weight, 1.5% by weight, 2.0% by weight, 2.5% by weight, 3.0% by weight, 3.5% by weight, 4.0% by weight, 4.5% by weight, 5.0% by weight, 5.5% by weight, 6.0% by weight, 6.5% by weight, 7.0% by weight, 7.5% by weight, 8.0% by weight, 8.5% by weight, 9.0% by weight, 9.5% by weight, 10.0% by weight, or within the range defined by any two of them, and / or the addition amount of the non-fibrillated binder can be 0.5% by weight, 1.0% by weight, 1.5% by weight, 2.0% by weight, 2.5% by weight, 3.0% by weight, 3.5% by weight, 4.0% by weight, 4.5% by weight, 5.0% by weight, 5.5% by weight, 6.0% by weight, 6.5% by weight, 7.0% by weight, 7.5% by weight, 8.0% by weight, 8.5% by weight, 9.0% by weight, 9.5% by weight, 10.0% by weight, or within the range defined by any two of them.

[0072] In some embodiments, based on the total weight of all components for mixing, the total addition amount of the non-fibrillated binder and the fibrillated binder is 1-15% by weight, preferably 1-10% by weight. For example, based on the total weight of all components for mixing, the total addition amount of the non-fibrillated binder and the fibrillated binder can be 1.0% by weight, 1.5% by weight, 2.0% by weight, 2.5% by weight, 3.0% by weight, 3.5% by weight, 4.0% by weight, 4.5% by weight, 5.0% by weight, 5.5% by weight, 6.0% by weight, 6.5% by weight, 7.0% by weight, 7.5% by weight, 8.0% by weight, 8.5% by weight, 9.0% by weight, 9.5% by weight, 10.0% by weight, 10.5% by weight, 11.0% by weight, 11.5% by weight, 12.0% by weight, 12.5% by weight, 13.0% by weight, 13.5% by weight, 14.0% by weight, 14.5% by weight, 15.0% by weight, or within the range defined by any two of them.

[0073] For the contents of the above-mentioned components, it is easy for those skilled in the art to understand that after the electrode membrane is prepared, based on the dry weight of the electrode membrane, the contents of the above-mentioned components are also within the above ranges respectively.

[0074] The electrode preparation method of the present invention has no special requirements for the mixing method, and the mixing methods commonly used in the art can be adopted. For example, mixing can be carried out by one or more of ball milling, jet milling, high-speed shearing machine or mechanical grinding. As an example, those skilled in the art can carry out mixing 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 within the range of 50 - 10,000 rpm, such as 50 rpm, 100 rpm, 300 rpm, 500 rpm, 1000 rpm, 2000 rpm, 3000 rpm, 5000 rpm, 8000 rpm, 10,000 rpm, or within the range defined by any two of them, and / or the mixing time is 5 - 720 minutes, such as 5 minutes, 30 minutes, 60 minutes, 120 minutes, 240 minutes, 300 minutes, 360 minutes, 420 minutes, 720 minutes, or within the range defined by any two of them. In addition, for example, zirconia can be used as the ball milling medium, and the volume ratio of zirconia is less than 30%. It is easy for those skilled in the art to understand that the treatment of the fibrillated binder added into a flocculent or muddy state can also be carried out by one or more of ball milling, jet milling (i.e., pneumatic mill or energy flow mill), high-speed shearing machine, or mechanical grinding. Therefore, preferably, in the embodiment, while mixing the mixture added with the fibrillated binder, the mixture is processed into a flocculent or muddy state.

[0075] Forming

[0076] The present invention has no special restrictions on the forming method of the flocculent or muddy product, and the technical means commonly used by those skilled in the art can be adopted. As an example, the flocculent or muddy product can be formed into an electrode membrane by one or more of roll pressing (such as hot roll forming), extrusion molding, injection molding, blow molding, coating molding, or casting molding, preferably roll pressing (such as hot roll forming), extrusion molding. Hot roll forming means that the fibrillated electrode material is formed by roll pressing through a hot roll press multiple times. During the roll pressing process, the flocculent or muddy powder material is roll pressed into shape. As the pressure and number of times increase, the thickness of the electrode membrane continuously decreases and the compaction density continuously increases. Heating can, on the one hand, improve the fluidity of the polymer and the processability of the electrode membrane, and on the other hand, enable the non-fibrillated binder to melt and uniformly coat and bond other components of the electrode membrane, realizing a tighter adhesion between the components of the electrode membrane. As an example, during the hot roll forming process, the roll pressing pressure range can be controlled to be 0.1×10 3 -20.0×10 3 kgf / cm 2 , the roll pressing temperature range is 10 - 200 °C, the roll pressing speed is 0.5 - 50 m / min, and the roll pressing number is 1 - 30 times. As an example, the roll pressing pressure can be 0.1×10 3, 0.2×10 3 , 0.3×10 3 , 0.5×10 3 , 0.8×10 3 , 1.0×10 3 , 2.0×10 3 , 5.0×10 3 , 10.0×10 3 , 15.0×10 3 , 20.0×10 3 kgf / cm 2 , or within the range defined by any two of them, and / or the rolling temperature can be 10, 20, 30, 40, 50, 60, 70, 80, 100, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 °C, or within the range defined by any two of them.

[0077] In some embodiments, preferably, there is no pre-forming step before performing step (b). Not performing the pre-forming step helps in the mass production of the electrode film, simplifies the process, and improves production efficiency.

[0078] In some embodiments, after the electrode film sheet is prepared, the obtained electrode film sheet is maintained at a temperature of 100 - 250 °C, preferably 150 - 200 °C, preferably in a vacuum for 4 - 20 h, preferably 8 - 16 h. By performing the above heat treatment on the electrode film sheet, the initial Coulombic efficiency can be improved. This is believed to be because the above heat treatment helps reduce side reactions during the charge and discharge of the electrode. As an example, the temperature for treating the obtained electrode film sheet can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250 °C, or within the range defined by any two of them, and / or the treatment time can be 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 h, or within the range defined by any two of them.

[0079] In some embodiments, the thickness of the electrode diaphragm obtained in the forming step is 10 - 1000 μm, preferably 50 - 200 μm. As an example, the thickness of the electrode diaphragm obtained 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 within the range defined by any two of them.

[0080] Depositing a current collector

[0081] After obtaining the electrode diaphragm, a metal layer is deposited as a current collector on one surface of the obtained electrode diaphragm by physical deposition, thereby obtaining an electrode.

[0082] In some embodiments, before depositing the current collector on the electrode diaphragm by physical deposition, a patterned mask is applied on the surface of the electrode diaphragm where the current collector is to be deposited. For example, the patterned mask can be selected from a rectangle, a triangle, a ring, etc. Applying the patterned mask is beneficial to reducing the amount of deposited current collector and saving costs; and the design of the mask pattern can achieve maintaining good current conduction while reducing the deposition amount.

[0083] In some embodiments, before depositing the current collector on the electrode diaphragm by physical deposition, the electrode diaphragm is subjected to at least one of the following pre-treatment steps: plasma cleaning and surface etching.

[0084] In some embodiments, the electrode diaphragm is pre-treated by plasma. For example, vacuum or non-vacuum plasma cleaning can be performed, and oxygen, helium, argon or xenon can be used as the process gas.

[0085] In some embodiments, the electrode diaphragm is pre-treated 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.

[0086] In the present invention, a current collector is deposited on one surface of the electrode diaphragm by physical deposition. As an example, the physical deposition method (physical vapor deposition method) can be selected from one or more of sputtering plating (such as magnetron sputtering), evaporation plating or ion plating.

[0087] In some embodiments, the physical deposition method is magnetron sputtering. For example, the target material for magnetron sputtering is selected from metallic materials, such as one or more of the elements or alloys selected from copper, aluminum, nickel, titanium, tin, iron, gold, and platinum. The process conditions for magnetron sputtering are as follows: the substrate temperature is 10 - 300 °C, preferably 20 - 200 °C, the rotation speed of the substrate (i.e., the electrode diaphragm) is 0 - 20 rpm, the target-substrate distance is 50 - 200 mm; the main chamber vacuum degree is 5×10 -3 -5×10 -6 Pa, the process gas pressure is 0.5 - 15 Pa, the power of the power supply is 20 - 500 W, and the sputtering time is 20 - 5000 s. The inventors have found through research that by regulating the substrate temperature during the magnetron sputtering process, it is beneficial to improve the peeling force between the current collector and the electrode diaphragm 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 the range defined by any two of them.

[0088] In some embodiments, the thickness of the current collector prepared by the electrode preparation method of the present invention 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 the range defined by any two of them.

[0089] In some embodiments, the ratio of the thickness of the current collector prepared by the method of the present invention to the thickness of the electrode diaphragm 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 diaphragm 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 the range defined by any two of them.

[0090] Electrode

[0091] The second aspect of the present invention provides an electrode prepared by the electrode preparation method according to the first aspect of the present invention.

[0092] Energy storage device

[0093] The third aspect of the present invention provides an energy storage device, which includes 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, includes the electrode according to the second aspect of the present invention.

[0094] 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.

[0095] Hereinafter, the energy storage device of the present invention will be described by taking a lithium-ion secondary battery as an example. Those skilled in the art can easily understand that the sodium-ion secondary battery, the lithium-sulfur secondary battery, or the capacitor, the supercapacitor, the lithium-ion capacitor of the present invention can be obtained by appropriately adjusting with reference to the description of the lithium-ion secondary battery.

[0096] Lithium-ion secondary battery

[0097] In some embodiments, the energy storage device of the present invention is a lithium-ion secondary battery.

[0098] The present invention does not particularly limit 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 adopted. In some embodiments, the positive electrode active material is selected from, for example, one or more of lithium transition metal composite oxides, composite oxides obtained by adding other transition metals or non-transition metals or non-metals to lithium transition metal composite oxides. In some embodiments, the layered transition metal oxide may have the 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, and the general formula satisfies valence balance. In addition, the layered transition metal oxide may also be doped with elements having high electronegativity, such as one or more of S, N, F, Br, Cl, I, CN, etc. For example, the positive electrode active material may be 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, lithium-containing phosphate in 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.

[0099] In some embodiments, based on the dry weight of the positive electrode sheet, the amount of the positive electrode active material is 80 - 98 wt%, preferably 90 - 98 wt%.

[0100] Those skilled in the art can easily understand that when the energy storage device of the present invention is a secondary battery, the secondary battery further includes an electrolyte.

[0101] In some embodiments, based on the dry weight of the negative electrode sheet, the amount of the negative electrode active material is 80 - 98 wt%, preferably 90 - 98 wt%.

[0102] Those skilled in the art can easily understand that when the energy storage device of the present invention is a secondary battery, the secondary battery further includes an electrolyte.

[0103] In some embodiments, the electrolyte is a non-aqueous liquid electrolyte. The present invention has no particular requirement on the type of the non-aqueous liquid electrolyte. The non-aqueous liquid electrolyte includes a non-aqueous organic solvent and an electrolyte lithium salt.

[0104] In some embodiments, the non-aqueous organic solvent can be selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl 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), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0105] In some embodiments, the electrolyte lithium salt may be selected from one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroborate (LiBF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluoro(dioxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0106] 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.

[0107] In some embodiments, the non-aqueous liquid electrolyte may also optionally include additives. As an example, the additives may include additives that contribute to the formation of a film on the negative electrode or the positive electrode, and may also include additives that can improve the battery performance, such as additives that improve the high-temperature or low-temperature performance of the battery, etc.

[0108] Those skilled in the art can easily understand that when the electrolyte is a liquid electrolyte, the lithium-ion secondary battery further includes a porous separator. The present invention does not particularly limit the porous separator used, and a porous structure separator with electrochemical stability and chemical stability commonly used can be used. For example, it can be a single-layer or multi-layer film of one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride, such as a three-layer porous PP / PE / PP film. When a solid electrolyte is used, the separator can also be omitted.

[0109] In some embodiments, the electrolyte is a gel electrolyte. The present invention does not particularly require the type of gel electrolyte, and any gel electrolyte commonly used in the art can be adopted. In some embodiments, the gel electrolyte may include a polymer matrix and a liquid electrolyte (including a lithium salt and a non-aqueous organic solvent). The polymer matrix may be selected from one or more of polyvinylidene fluoride (PVDF), vinylidene fluoride - hexafluoropropylene copolymer P(VDF - HFP), polyethylene oxide (PEO), polyacrylonitrile (PAN), and polymethyl methacrylate (PMMA). The liquid electrolyte may be the same as that described above.

[0110] Similarly, those skilled in the art can easily understand that when the electrolyte is a gel electrolyte, a porous separator may also be optionally included. The gel electrolyte can at least partially fill the pores of the porous separator. The description of the porous separator is the same as that of the porous separator used for the liquid electrolyte.

[0111] In some embodiments, the electrolyte is a solid electrolyte. The present invention does not particularly limit the type of the solid electrolyte, and any solid electrolyte conventionally used in the art can be adopted. The solid electrolyte can be selected from one or more of inorganic solid electrolytes or polymer electrolytes, preferably selected from one or more of oxides, sulfides, and polymers. For example, the solid electrolyte can be selected from one or more of lithium garnet oxide (Li7La3Zr2O 12 , abbreviated as LLZO), tin oxide (SnO2), bismuth oxide (Bi2O3), lithium sulfide (Li2S), sodium sulfide (Na2S), silicate, phosphate, siloxane, perovskite oxide, lithium oxide, and polymer solid electrolyte, etc.

[0112] The energy storage device of the present invention has been described above by taking the 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 invention can also be a sodium-ion secondary battery, a lithium-sulfur secondary battery, or a capacitor (such as a supercapacitor, a lithium-ion capacitor). And those skilled in the art can refer to the lithium-ion secondary battery described above and make appropriate adjustments to obtain the sodium-ion secondary battery, the lithium-sulfur secondary battery, or the capacitor (such as a supercapacitor, a lithium-ion capacitor) of the present invention.

[0113] In some embodiments, the energy storage device of the present invention 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 analogs, preferably one or more of 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, based on the dry weight of the positive electrode diaphragm, the amount of the positive electrode active material is 80-98% by weight, preferably 90-98% by weight; and / or

[0114] 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, based on the dry weight of the negative electrode diaphragm, the amount of the negative electrode active material is 80-98% by weight, preferably 90-98% by weight.

[0115] In some embodiments, the energy storage device of the present invention 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, and phosphorus sulfide, or compounds in which an organic compound having a straight-chain alkyl group, a branched-chain alkyl group, a cycloalkane, an aromatic hydrocarbon, or an aromatic hydrocarbon containing a heteroatom is combined with sulfur, preferably one or more of a sulfur-carbon composite positive electrode material and polyacrylonitrile sulfide. Preferably, based on the dry weight of the positive electrode membrane, the amount of the positive electrode active material is 80-98% by weight, preferably 90-98% by weight; and / or

[0116] The negative electrode active material can be a negative electrode active material commonly used in lithium-sulfur secondary batteries, for example, selected from metallic lithium. Preferably, based on the dry weight of the electrode membrane, the amount of the negative electrode active material is 80-99% by weight, preferably 90-99% by weight.

[0117] In some embodiments, the energy storage device of the present invention 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, and carbon materials, preferably one or more of MnO2, NiO, Co3O4, polyaniline, polypyrrole, activated carbon, graphene, and biochar. Preferably, based on the dry weight of the positive electrode membrane, the amount of the positive electrode active material is 80-98% by weight, preferably 90-98% by weight; and / or

[0118] The negative electrode active material is selected from one or more of metals, carbon materials, conductive polymers, metal oxides, and metal-organic framework (MOF) derived materials, preferably one or more of aluminum, zinc, activated carbon, graphite, polyaniline, polypyrrole, polythiophene, and MnO2. Preferably, based on the dry weight of the negative electrode membrane, the amount of the negative electrode active material is 80-98% by weight, preferably 90-98% by weight.

[0119] For supercapacitors or lithium-ion capacitors, those skilled in the art can obtain them by making appropriate adjustments with reference to the above embodiments.

[0120] Embodiment

[0121] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0122] I. Measurement methods

[0123] 1. Scanning electron microscopy test

[0124] Fix the prepared electrode film on the sample stage and send it into the sample chamber of a scanning electron microscope (Zeiss Gemini) to observe the surface morphology of the electrode film.

[0125] 2. Volume-average particle size D v 50

[0126] Add the sample to be measured to an appropriate amount of ethanol solvent so that the concentration of the sample to be measured is 0.01 g / L, and ultrasonically disperse it to form a dispersion. Then use a Mastor 2000 laser particle size analyzer for testing to obtain equivalent particle size distribution information.

[0127] 3. Peel force

[0128] Fix the active material surface of the composite electrode to be measured on a horizontally placed substrate, and attach a test tape to the current collector side. Fix the tape and the substrate to a universal testing machine ZWICK Z020 through clamps, with both ends at 180°. Start stretching at a rate of 5 cm / min, that is, perform current collector peeling on the electrode surface, and record the peel force and displacement information.

[0129] 4. Thermal performance test

[0130] Use differential scanning calorimetry (DSC) for testing. During the test, record the heat absorption and heat release information during the heating process of the electrode film to characterize the phase transition of the non-fibrillating binder during the heat treatment process. The test conditions are as follows: Use a Q5000IR instrument, the atmosphere is argon, and heat up from 20 °C to 300 °C at a heating rate of 10 °C / min. Record the signal during the heating process as the measurement result.

[0131] 5. Electrochemical performance test of the electrode

[0132] 5.1 Cyclic voltammetry curve

[0133] Cyclic voltammetry tests are performed using an electrochemical workstation (CHI660e, Chenhua). The voltage range is 0.005 V - 2 V. The cyclic voltammetry curve is measured at a scanning rate of 1 mV s-1. During the measurement, first reduce the voltage from 2 V to 0.005 V, and then increase it from 0.005 V to 2 V.

[0134] 5.2 Impedance

[0135] Electrochemical impedance is measured using Chenhua CHI660e. The measurement conditions for electrochemical impedance are: the frequency range is from 100 kHz to 0.01 Hz, and the amplitude of the alternating voltage is 10 mV.

[0136] 5.3 Charge and discharge test of the battery

[0137] Battery cycle data is collected at room temperature using a battery tester (LAND, 2001CT).

[0138] 5.3.1 Charge and Discharge Tests of Lithium-Ion Batteries

[0139] Charge and Discharge Tests of Half-Cells

[0140] The charge and discharge test conditions for the negative half-cell are as follows: At a temperature of 30 °C, charge the CR2032 button half-cell at a current rate of 0.5C to 1.5V, then let it stand for 5 minutes, and then discharge it at a current rate of 0.5C to 0.005V, and then let it stand for 5 minutes. This is one charge-discharge cycle. Record the discharge capacity and charge capacity during the first charge-discharge cycle as the first discharge capacity (i.e., the de-lithiation capacity, the same below) and the first charge capacity (i.e., the intercalation capacity, the same below). Similarly, record the discharge capacity and charge capacity during the nth cycle as the discharge capacity and charge capacity of the nth cycle respectively.

[0141] The charge and discharge test conditions for the positive half-cell are as follows: At a temperature of 30 °C, charge the CR2032 button half-cell at a current rate of 0.5C to 4.3V, then let it stand for 5 minutes, and then discharge it at a current rate of 0.5C to 3.0V, and then let it stand for 5 minutes. This is one charge-discharge cycle. Record the discharge capacity and charge capacity during the first charge-discharge cycle as the first discharge capacity and the first charge capacity. Similarly, record the discharge capacity and charge capacity during the nth cycle as the discharge capacity and charge capacity of the nth cycle respectively.

[0142] Charge and Discharge Tests of Full Cells:

[0143] The charge and discharge test conditions for the assembled full cell are as follows: At a temperature of 30 °C, charge the cell at a current rate of 0.5C to 4.3V, then let it stand for 5 minutes, and then discharge it at a current rate of 0.5C to 3.0V, and then let it stand for 5 minutes. This is one charge-discharge cycle. Record the discharge capacity and charge capacity during the first charge-discharge cycle as the first discharge capacity and the first charge capacity. Similarly, record the discharge capacity and charge capacity during the nth cycle as the discharge capacity and charge capacity of the nth cycle respectively.

[0144] Divide the measured discharge capacity of the negative half-cell by the mass of the negative electrode to obtain the discharge specific capacity of the entire negative electrode; divide the measured discharge capacity by the mass of the negative electrode active material to obtain the discharge specific capacity of the negative electrode active material.

[0145] Similarly, divide the measured discharge capacity of the positive half-cell by the mass of the positive electrode to obtain the discharge specific capacity of the entire 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 specific capacity of the positive electrode active material.

[0146] Similarly, the discharge specific capacity (discharge gram capacity) of the positive electrode sheet is obtained by dividing the discharge capacity measured for the full cell by the mass of the positive electrode.

[0147] In the above test, the first Coulombic efficiency is obtained by dividing the first discharge capacity by the first charge capacity and then multiplying by 100%.

[0148] In the above test, the remaining capacity percentage of the nth cycle is obtained by dividing the charge capacity at the nth cycle by the first charge capacity and then multiplying by 100%.

[0149] 5.3.2 Charge and Discharge Tests of Sodium-Ion Secondary Batteries

[0150] The charge and discharge test conditions for the assembled battery are as follows: at a temperature of 30 °C, the battery is charged to 4 V at a current rate of 0.5C, then left to stand for 5 min, and then discharged to 2 V at a current of 0.5C, and then left to stand for 5 min. This is one charge and discharge cycle. Record the discharge capacity and charge capacity during the first charge and discharge cycle as the first discharge capacity and the first charge capacity.

[0151] 5.4 Capacitance Tests of Supercapacitors

[0152] The capacitance of the supercapacitor is tested according to the national standard GBT34870.1-2017.

[0153] II. Examples

[0154] Example 1: Influence of the Addition of Non-Fibrillated Binder on Processing and Molding

[0155] Mix NCM523, conductive carbon black (TIMCAL Super P Li, the same below), polytetrafluoroethylene (Chemours 601X, the same below) (fibrillated binder), and sodium carboxymethyl cellulose (DAICEL CMC2200, the same below) (non-fibrillated binder) in a mass ratio of 85:5:5:5, and ball mill at a rotation speed of 100 rpm for 30 min (ball milling conditions: zirconia grinding balls, volume ratio less than 30%. Unless otherwise specified, the ball milling conditions in other examples are the same). After ball milling, the resulting mixture is in a flocculent or muddy state. Then, roll extrusion is carried out at 180 °C (pressure 500 kgf / cm 2 ) until the thickness reaches 80 μm, and it is named positive electrode sheet 21.

[0156] Positive electrode sheet 22 does not use non-fibrillated binder, that is, the ratio of NCM523, conductive carbon black, and polytetrafluoroethylene is 85:5:10, and other preparation processes are the same as those of positive electrode sheet 21.

[0157] As Figure 1 and Figure 2As shown, in the absence of the non-fibrillating binder, the positive electrode particles are compacted and broken under pressure, making the surface of the electrode membrane brittle and cracked. This may be because the non-fibrillating binder helps relieve stress during the rolling process.

[0158] Example 2: Effect of the addition of the non-fibrillating binder on the electrochemical performance

[0159] Graphite (S360-L2-H), conductive carbon black (TIMCAL SuperP Li), polytetrafluoroethylene (MSK-F104) (fibrillating binder), and polyvinylidene fluoride (HSV900) (non-fibrillating binder) were mixed at a mass ratio of 85:5:5:5 and ball-milled for 30 min at a rotation speed of 300 rpm until evenly mixed. The resulting mixture was in the form of flocs or mud. Then, it was roll-extruded at 180 °C (pressure 800 kgf / cm 2 ) until the thickness reached 60 μm, and it was named negative electrode membrane 1.

[0160] For negative electrode membrane 2, the non-fibrillating binder was not used, i.e., the ratio was graphite:conductive carbon black:polytetrafluoroethylene = 85:5:10, and the other preparation processes were the same as those for negative electrode membrane 1.

[0161] A 2-μm-thick copper metal layer was deposited on the surfaces of the two negative electrode membranes by magnetron sputtering to obtain negative electrode 1 and negative electrode 2, respectively. The magnetron sputtering conditions were as follows: the substrate temperature was 30 °C, the substrate rotation speed was 0 rpm, the target-substrate distance was 80 mm; the main chamber vacuum was 8×10 -4 Pa, the process gas (argon) pressure was 0.5 Pa, the power supply power was 120 W, and the sputtering time was 2500 s.

[0162] After depositing the copper metal layer, slicing and vacuum drying were carried out. Then, it was transferred to a glove box and assembled into a CR2032 button half-cell under an argon atmosphere. The counter electrode used a 450-μm-thick lithium sheet, and the electrolyte was a 50-μL solution of 1 M LiPF6 in ethylene carbonate (EC):diethyl carbonate (DEC) = 1:1 (by the total volume fraction of EC + DEC, adding 10% fluoroethylene carbonate (FEC) and 1% vinylene carbonate (VC)). The separator was Celgard 2500 with a thickness of 30 μm.

[0163] As Figure 3 shown, 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 significant. In contrast, in the case of adding the non-fibrillating binder, negative electrode 1 showed a significantly reduced electrode side reaction.

[0164] Figure 4Describes the constant current first charge and discharge curve graph of the CR2032 button half-cell assembled with the negative electrode 1 and negative electrode 2 prepared in Example 2. Compared with the negative electrode 2, the negative electrode 1 increases the first Coulombic efficiency from 68% to 80%.

[0165] Example 3: Influence of the addition sequence of fibrillated binder

[0166] Prepare negative electrode film sheets 3, 4, and 5 with the mass ratio of silicon carbide (Kolode 950K)∶conductive carbon black (TIMCAL C45)∶polytetrafluoroethylene (MSK-F104) (fibrillated binder)∶sodium alginate (Kolode) (non-fibrillated binder) being 93∶2∶2.5∶2.5.

[0167] For negative electrode film sheet 3, first shear-mix silicon carbide, conductive carbon black, and sodium alginate at 8000 rpm for 30 minutes, then add polytetrafluoroethylene and repeat once, and the resulting mixture is in a flocculent or muddy state; for negative electrode film sheet 4, shear-mix silicon carbide, conductive carbon black, polytetrafluoroethylene, and sodium alginate simultaneously at 8000 rpm for 30 minutes, and then the resulting mixture is in a flocculent or muddy state; for negative electrode film sheet 5, first shear-mix silicon carbide, conductive carbon black, and polytetrafluoroethylene at 8000 rpm for 30 minutes, then add sodium alginate and repeat once, and the resulting mixture is in a flocculent or muddy state.

[0168] The forming of negative electrode film sheets 3, 4, and 5, and subsequent magnetron sputtering and half-cell assembly are the same as in Example 2. The first Coulombic efficiency and discharge specific capacity of the half-cells corresponding to negative electrode film sheets 3, 4, and 5 are summarized in Table 1.

[0169] Table 1 Electrochemical properties of the half-cells corresponding to negative electrode film sheets 3 - 5

[0170]

[0171] It can be seen from Table 1 that during the mixing process, the later the addition sequence of the fibrillated binder such as polytetrafluoroethylene, the better the electrochemical performance of the corresponding electrode. Without wishing to be bound by any theory, this may be because the fibrillation process of the fibrillated binder such as polytetrafluoroethylene will hinder the uniform dispersion of the particles.

[0172] Example 4: Influence of heat treatment of the electrode film sheet

[0173] Mix graphite (BTR-918)∶Ketjen black (EC 600JD)∶polyacrylic acid (LA133) (non-fibrillating binder)∶polytetrafluoroethylene (MSK-F104) (fibrillating binder) in a mass ratio of 80∶10∶5∶5, and disperse evenly by processing with a jet mill (the process gas is compressed air, the air pressure is 0.3 MPa, room temperature, the same below) for 1 h. The resulting mixture is in a flocculent or muddy state. Then, roll extrusion is carried out at room temperature (pressure 100 kgf / cm 2 ) until the thickness reaches 100 μm, and negative electrode sheets 6 and 7 are prepared respectively. In addition, negative electrode sheet 6 is further stored in vacuum at 180 °C for 12 h and then cooled naturally; negative electrode sheet 7 is not treated. The forming of negative electrode sheets 6 and 7 (thus obtaining negative electrodes 6 and 7), and subsequent magnetron sputtering and half-cell assembly are the same as in Example 2.

[0174] Figure 5 To show the heat flow curve of the negative electrode sheet 6 prepared in Example 4. In Figure 5 , the heat flow of negative electrode sheet 6 first decreases with the increase of temperature, reaches the lowest at about 165 °C, then rises rapidly and tends to be stable. It shows that the non-fibrillating binder undergoes a phase change and melts from the initial powder state. After cooling, it solidifies again and binds the electrode material particles together.

[0175] Figure 6 Shows the first constant-current charge-discharge curves of CR2032 button half-cells assembled with negative electrodes 6 and 7 prepared in Example 4 respectively. When the negative electrode sheet is heat-treated before magnetron sputtering, the electrode side reaction is significantly reduced.

[0176] Figure 7 Shows a comparison chart of the first Coulombic efficiency of CR2032 button half-cells assembled with negative electrodes 6 and 7 prepared in Example 4 respectively. Compared with negative electrode 7, negative electrode 6 improves the first Coulombic efficiency from about 70% to about 83%.

[0177] Example 5: Interface adhesion and impedance

[0178] Mix lithium iron manganese phosphate (LiFeMnPO4), carbon nanotubes (CNT-3213), sodium alginate (Colud), and polytetrafluoroethylene (Chemours 601X) in a mass ratio of 86∶4∶7∶3, and disperse for 60 min using a jet mill (the same as above). The resulting mixture is in a flocculent or muddy state. Then, roll pressing is carried out at 150 °C (1×10 3 kgf / cm 2 ) to a thickness of 150 μm to prepare a positive electrode sheet.

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

[0180] Then, the peel strength between the positive electrode film and the corresponding current collector in positive electrodes 26 - 28 was tested, and the results were summarized in Table 2.

[0181] Table 2 Test results of the peel strength of the positive electrode current collector

[0182] Number Peak stripping force / N Average stripping force / N Positive electrode 26 14.45 6.52 Positive electrode 27 18.95 12.47 Positive electrode 28 37.25 19.68

[0183] As can be seen from Table 2, compared with positive electrode 26 prepared by laminating the positive electrode film with a commercial carbon-coated aluminum foil, in the positive electrodes prepared by physical deposition such as magnetron sputtering, the peel strength between the positive electrode film and the current collector is greater both in terms of the peak peel strength and the average peel strength. In addition, the peel strength of positive electrode 28 with a substrate temperature of 150 °C during the sputtering process is greater than that of positive electrode 27 with a substrate temperature of 25 °C.

[0184] The prepared electrodes were assembled into CR2032 button half-cells in the manner described in Example 6, and then impedance tests were carried out.

[0185] Figure 8 Figure showing the electrochemical impedance (ohm) spectra of positive electrodes 26, 27, and 28 prepared according to Example 5 respectively. As can be seen Figure 8 from it, compared with positive electrode 26 prepared by laminating the positive electrode film with a commercial carbon-coated aluminum foil, positive electrodes 27 and 28 with a current collector deposited by physical deposition such as magnetron sputtering have lower impedance, especially the impedance of positive electrode 28 is lower than that of positive electrode 27.

[0186] Example 6: Specific capacity and capacity retention ratio

[0187] The preparation process of the dry electrode is as follows:

[0188] Mix various components according to the mass ratio of graphite (MS-QCG-X)∶Ketjen black (EC-300J)∶sodium carboxymethyl cellulose (DAICEL CMC2200)∶polytetrafluoroethylene (MSK-F104) = 80∶10∶6∶4, and disperse them with a high-speed shearer at 5000 rpm for 4 h. The resulting mixture is in a flocculent or muddy state. Then roll-press it at 180 °C (800 kgf / cm 2 ) to a thickness of 70 μm, then store it in a vacuum at 180 °C for 16 h and naturally cool it to room temperature to obtain the negative electrode film.

[0189] Thermocompression laminate the obtained negative electrode film with a commercial carbon-coated copper foil (MTI, 12 μm copper + 1 μm carbon coating) at 180 °C, 200 kgf / cm 2 ) to obtain the negative electrode 11; deposit a 1-μm-thick copper and aluminum current collector on the obtained negative electrode film by magnetron sputtering to obtain the negative electrode 12. The magnetron sputtering conditions are: substrate temperature 150 °C, substrate rotation speed 5 rpm, target-substrate distance 145 mm, main chamber vacuum degree 8×10 -6 Pa, argon gas pressure 0.5 Pa, sputtering power 150 W, sputtering time 75 min.

[0190] Mix various components according to the mass ratio of NCM523 (T52S)∶Ketjen black (EC-300J)∶sodium carboxymethyl cellulose (DAICEL CMC2200)∶polytetrafluoroethylene (MSK-F104) = 80∶10∶6∶4, and disperse them with a high-speed shearer at 5000 rpm for 4 h. The resulting mixture is in a flocculent or muddy state. Then roll-press it at 180 °C (600 kgf / cm 2 ) to a thickness of 100 μm, then store it in a vacuum at 180 °C for 16 h and naturally cool it to room temperature to obtain the positive electrode film.

[0191] Thermocompression laminate the obtained positive electrode film with a commercial carbon-coated aluminum foil (MTI, 20 μm aluminum + 1 μm carbon coating) at 180 °C, 200 kgf / cm 2 ) to obtain the positive electrode 29; deposit a 1-μm-thick aluminum current collector on the obtained positive electrode film by magnetron sputtering to obtain the positive electrode 30. The magnetron sputtering conditions are: substrate temperature 150 °C, substrate rotation speed 5 rpm, target-substrate distance 145 mm, main chamber vacuum degree 8×10 - 6 Pa, argon gas pressure 0.5 Pa, sputtering power 150 W, sputtering time 75 min.

[0192] The preparation process of the wet electrode is as follows:

[0193] Prepare the wet-type anode as follows: According to the mass ratio of graphite (MS-QCG-X): Ketjen black (EC-300J): polyvinylidene fluoride (SHV900) = 80:10:10 (maintaining the same binder ratio as anodes 11 and 12), disperse the materials in NMP with a solid content of 50%, and use a ball mill to mill at 300 rpm for 30 min to form a uniform and flowable slurry. Use a doctor blade to evenly coat the slurry on a copper foil, and obtain the wet-type anode (i.e., wet-type graphite @ commercial copper) after vacuum drying.

[0194] Prepare the wet-type cathode as follows: According to the mass ratio of NCM523 (T52S): Ketjen black (EC-300J): polyvinylidene fluoride (SHV900) = 80:10:10 (maintaining the same binder ratio as cathodes 29 and 30), disperse the materials in NMP with a solid content of 40%, and use a ball mill to mill at 500 rpm for 40 min to form a uniform and flowable slurry. Use a doctor blade to evenly coat the slurry on an aluminum foil, and obtain the wet-type cathode (i.e., wet-type NCM523 @ commercial aluminum) after vacuum drying.

[0195] Assemble the dry-type and wet-type anodes prepared above into a negative CR2032 button half-cell in the manner of Example 2.

[0196] Manufacture a positive CR2032 button half-cell in a manner similar to the negative CR2032 button half-cell, except as follows: Use the dry-type and wet-type cathodes prepared above instead of the dry-type and wet-type anodes prepared above as the working electrode, and use lithium metal as the counter electrode.

[0197] Measure the discharge specific capacity of the electrode active material and the overall discharge specific capacity of the electrode for the half-cells corresponding to anodes 11-12 and cathodes 29-30, respectively. Figure 9 Present the test results of the discharge specific capacity of the negative half-cell corresponding to anodes 11-12. Figure 10 Present the test results of the discharge specific capacity of the positive half-cell corresponding to cathodes 29-30 at different rates.

[0198] From Figure 9 - 10 It can be seen that under the same other conditions, compared with the electrodes prepared by hot pressing and laminating the dry-type electrode film and the commercial current collector, in the electrodes prepared by the method of the present invention, the electrode active material and the overall electrode have higher discharge specific capacities (including the first discharge specific capacity and the cyclic discharge specific capacity). This is beneficial to improving the energy density of the energy storage device and improving the cyclic performance of the energy storage device.

[0199] In addition, the inventor also studied the cyclic discharge specific capacity of the electrode at different rates. See Figure 10, even when the charge-discharge rate is changed, the electrode prepared by the method of the present invention still has a higher cyclic discharge specific capacity of the electrode active material and a cyclic discharge specific capacity of the overall electrode than the electrode prepared by thermocompression lamination of a dry electrode film and a commercial current collector, indicating that the energy storage device such as a secondary battery using the electrode prepared by the preparation method of the present invention also has improved rate performance.

[0200] Furthermore, the inventors also replaced the positive electrode active material with lithium iron phosphate, lithium cobaltate, and NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2) prepared by different methods, replaced the negative electrode active material with silicon-carbon materials prepared by different methods, and prepared the positive electrode or negative electrode in the same manner (except that the active materials are different and other conditions are the same). Then, the discharge specific capacity of the active material, the discharge specific capacity of the positive electrode of the electrode, and the capacity remaining ratio were measured, and the test results are summarized in Table 3.

[0201] Table 3 Specific capacity and capacity remaining ratio of different electrodes after 100 cycles

[0202]

[0203]

[0204] *: "Dry method" means that the electrode active material, conductive additive, non-fibrillated binder, and fibrillated binder are made into an electrode by the method of the present invention;

[0205] **: "Wet method" means that the electrode active material, conductive additive, and binder are uniformly dispersed in a solvent to form a slurry with a certain fluidity, and the electrode slurry is scraped and coated on a metal foil current collector and dried to prepare an electrode;

[0206] ***: The active material specific capacity and the overall electrode specific capacity in Table 3 are the results measured at a rate of 0.5C.

[0207] As can be seen from Table 3, when different electrode active materials are used for testing, compared with the wet electrode film and the electrode prepared by thermocompression lamination of a dry electrode film and a commercial current collector, the electrode prepared by the dry electrode film of the present invention and the magnetron sputtering current collector has a higher overall cyclic discharge specific capacity of the electrode, and the specific capacity of the active substance has been significantly improved.

[0208] In addition, the secondary battery including the electrode prepared by the method of the present invention has a higher capacity remaining ratio after 100 cycles, indicating that the life characteristics of the secondary battery have been improved.

[0209] Example 7: Cyclic discharge specific capacity and energy density of secondary battery

[0210] 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 commercial carbon-coated current collectors) 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 magnetron sputtering deposition current collectors) 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 according to the ratio of the negative electrode capacity to the positive electrode capacity (N / P ratio) = 1.15. The separator and electrolyte used in the secondary batteries were the same as those in Example 2.

[0211] Figure 11 Graphs showing 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 number of cycles are presented. From Figure 11 it can be seen that the overall secondary battery using a magnetron sputtering current collector has a higher cyclic discharge specific capacity. This indicates that energy storage devices such as secondary batteries prepared by the method of the present invention have improved cyclic performance.

[0212] Figure 12 Graphs showing the charge-discharge voltage of the first charge-discharge cycle of the secondary battery using a commercial current collector and the secondary battery using a magnetron sputtering current collector versus the overall discharge specific capacity of the secondary battery are presented. From Figure 12 it can be seen that the secondary battery using a magnetron sputtering current collector can provide a higher discharge specific capacity under the same electrochemical window.

[0213] The inventors further changed the types of electrode active materials, prepared other secondary batteries under the same conditions, and tested the energy densities of these secondary batteries. The test results are summarized in Table 4.

[0214] Table 4 Test Results of Energy Density

[0215]

[0216] It can be seen from Table 4 that the secondary battery using a magnetron sputtering current collector has a higher energy density compared to the secondary battery using a commercial current collector.

[0217] Example 8: Supercapacitor

[0218] Activated carbon, Ketjen black, polyvinylidene fluoride, and polytetrafluoroethylene were mixed in a mass ratio of 90:5:1:4, and dispersed by a jet mill for 0.5 h to mix evenly. The resulting mixture was in a flocculent or muddy state, and then roll-pressed (pressure 500 kgf / cm 2 , 160 °C) to a thickness of 100 μm to obtain an electrode film.

[0219] The two prepared electrode diaphragms are hot-pressed (temperature 180 °C, pressure 200 kgf / cm 2 ) with a commercial carbon-coated 20-μm aluminum foil for lamination, and are used as the positive and negative electrodes respectively (Combination 1, i.e., activated carbon | commercial aluminum foil).

[0220] In addition, two prepared electrode diaphragms are respectively deposited with a 1-μm aluminum current collector by magnetron sputtering. The magnetron sputtering conditions are as follows: substrate temperature 100 °C, substrate rotation speed 5 rpm, target-substrate distance 65 mm, main chamber vacuum degree 8×10 -4 Pa, argon gas pressure 0.5 Pa, sputtering power 150 W, and sputtering time 15 min. The obtained electrodes are used as the positive and negative electrodes respectively (Combination 2, i.e., activated carbon | magnetron aluminum).

[0221] The positive and negative electrode Combinations 1 and 2 prepared above (i.e., activated carbon | commercial aluminum foil and activated carbon | magnetron aluminum) are respectively assembled into capacitors, which are capacitors with a symmetric structure. The electrolyte used therein is a 6M KOH aqueous solution.

[0222] Partial parameters of the activated carbon electrodes are summarized in Table 5.

[0223] Table 5 Parameters of Activated Carbon Electrodes (under the same active material loading)

[0224]

[0225] Table 6 Performance of Activated Carbon Supercapacitors (under the same active material loading)

[0226]

[0227] It can be seen from Tables 5-6 that compared with the capacitors prepared by Combination 1 (i.e., activated carbon | commercial aluminum foil), the supercapacitors prepared by the method of the present invention have a significantly higher proportion of active material, and the electrode active material unexpectedly has a higher specific capacitance. Therefore, the supercapacitors prepared by the method of the present invention have a significantly higher overall specific capacitance and energy density.

[0228] Example 9: Sodium-Ion Secondary Battery

[0229] Hard carbon: conductive carbon black: sodium carboxymethyl cellulose: polytetrafluoroethylene are mixed in a mass ratio of 90:4:3:3, and the obtained mixture is dispersed by a jet mill for 0.5 h, and the obtained mixture is in a flocculent or muddy state. Then the obtained flocculent or muddy product is roll-pressed at 180 °C (pressure 800 kgf / cm 2 ) to a thickness of 100 μm to obtain a negative electrode diaphragm.

[0230] Mix Prussian blue (Na2FeFe(CN)6(NaHCF)), conductive carbon black, sodium carboxymethyl cellulose, and polytetrafluoroethylene in a mass ratio of 90∶4∶3∶3, and then disperse the mixture for 0.5 h using a jet mill (under the same conditions as before). The resulting mixture is in a flocculent or muddy state. Then roll press the resulting flocculent or muddy product at 180 °C (pressure 600 kgf / cm 2 ) to a thickness of 100 μm to obtain a positive electrode film.

[0231] Vacuum store the negative electrode film and the positive electrode film at 150 °C for 24 h, and then naturally cool to room temperature.

[0232] Thermocompression laminate the obtained positive electrode film and negative electrode film with a commercially available carbon-coated 20-μm aluminum foil respectively to obtain positive and negative electrodes on commercial aluminum foil. Magnetron sputter deposit a 1-μm aluminum current collector on the obtained positive electrode film and negative electrode film respectively. The magnetron sputtering conditions are: substrate temperature 150 °C, substrate rotation speed 5 rpm, target-substrate distance 80 mm, main chamber vacuum degree 8×10 -6 Pa, argon gas pressure 0.5 Pa, sputtering power 80 W, sputtering time 20 min to obtain positive and negative electrodes by magnetron sputtering.

[0233] Separator: Celgard 2325, thickness 30 μm;

[0234] Electrolyte: A solution of 1 M NaPF6 in DME (100 vol%).

[0235] Assemble the obtained positive and negative electrodes with the separator and the electrolyte into a sodium-ion secondary battery (N / P ratio = 1.15).

[0236] Table 7 Summary of some parameters of the sodium-ion secondary battery (at the same active material loading)

[0237]

[0238] Table 8 Performance comparison of sodium-ion batteries

[0239]

[0240] 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 invention is more compact and lightweight, and unexpectedly, the electrode active material has a higher specific capacity. Therefore, the sodium-ion secondary battery prepared by the method of the present invention has a significantly higher energy density.

[0241] Example 10: Depositing a current collector by evaporation coating

[0242] Disperse NCM523∶Ketjen black∶sodium carboxymethyl cellulose∶polytetrafluoroethylene in a mass ratio of 80∶10∶6∶4 with a high-speed shearer at 5000 rpm for 4 h, and the resulting mixture is in a flocculent or muddy state. Then roll the resulting flocculent or muddy product at 180 °C to a thickness of 100 μm to obtain a positive electrode film. Store the obtained positive electrode film in a vacuum at 180 °C for 16 h and naturally cool it to room temperature. Then deposit an aluminum layer with a thickness of 1 μm on the surface of the cooled positive electrode film by vacuum evaporation, and the evaporation conditions are: evaporation temperature 680 °C, vacuum degree 10 -2 Pa, and the evaporation duration is 15 min.

[0243] The above description is only an exemplary embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, improvements can still be made to the present invention, but these all fall within the protection scope of the present invention.

Claims

1. An electrode preparation method comprising: (1) Preparing an electrode membrane, comprising: (a) Mixing The electrode active material, the conductive additive, and the non-fibrillated binder are uniformly mixed, and then the fibrillated binder is added, and the resulting mixture is processed into a flocculent or muddy state; or The electrode active material, the conductive additive, the non-fibrillated binder and the fibrillated binder are uniformly mixed, and the obtained mixture is processed into a flocculent or muddy state; (b) Molding forming the flocculent or muddy product obtained in step (a) into an electrode membrane; (2) Depositing a current collector, comprising: A metal layer is deposited as a current collector on one surface of the electrode film obtained in step (1) by a physical deposition method.

2. The electrode preparation method according to claim 1, wherein step (1) further comprises, after the electrode membrane is prepared, keeping the obtained electrode membrane at a temperature of 100-250°C, preferably 150-200°C, preferably in a vacuum for 4-20h, preferably 8-16h.

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

4. The electrode preparation method according to any one of claims 1 to 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 the following: ball milling, jet milling, high-speed shearing machine, or mechanical milling; ii. The flocculent or muddy product obtained in step (a) is formed into an electrode membrane by one or more of the following: rolling (e.g., hot roll forming), extrusion forming, injection molding, blow molding, coating molding, or casting molding, preferably rolling (e.g., hot roll forming) or extrusion molding. Preferably, the rolling conditions are: the rolling temperature is 10-200° C., the rolling pressure is 0.1×10 3 -20.0×10 3 kgf / cm 2 , the rolling speed is 0.5-50m / min, and the number of rolling times is 1-30 times; iii. Step (2) comprises depositing a patterned metal layer as a current collector on the one surface of the electrode membrane obtained in (1); iv. Step (2) comprises, before depositing the metal layer, performing one or more pre-treatment steps selected from the following on the electrode membrane: plasma cleaning and surface etching; Preferably, the process gas for plasma cleaning is selected from one or more of oxygen, helium, argon or xenon: Preferably, the surface etching time is 1-10 min; or v. There is no preforming step prior to step (b).

5. The electrode preparation method according to any one of claims 1 to 4, wherein one or more of the following conditions are met: vi. The non-fibrillating binder is selected from one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose, polyacrylic acid, polyvinyl alcohol, sodium alginate, poly(ethylene oxide), polyacrylonitrile (PAN), polyimide (PI), cellulose and cellulose derivatives (such as cellulose acetate, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), cellulose nitrate, 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 carboxymethyl cellulose, polyacrylic acid and sodium alginate; vii. The fibrillated binder is selected from polytetrafluoroethylene; viii. Based on the dry weight of the electrode membrane, the weight ratio of the amount of the fibrillated binder added to the amount of the non-fibrillated binder added is 0.1:1 to 10:1, preferably 0.1:1 to 3.0:1; ix. Based on the dry weight of the electrode membrane, the fibrillated binder is added in an amount of 0.5-10% by weight, preferably 1-5% by weight; x. Based on the dry weight of the electrode membrane, the non-fibrillated binder is added in an amount of 0.5-10% by weight, preferably 1-8% by weight; or xi. Based on the dry weight of the electrode membrane, the total addition amount of the non-fibrillating binder and the fibrillating binder is 1-15 wt %, for example 1-10 wt %.

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

7. The electrode preparation method according to any one of claims 1 to 6, wherein one or more of the following conditions are met: xii. The ratio of the thickness of the current collector to the thickness of the electrode membrane 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 μm, preferably 0.5-2 μm; or xiv. The thickness of the electrode membrane is 10-1000 μm, preferably 50-200 μm.

8. An electrode, prepared according to the electrode preparation method according to any one of claims 1 to 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 the positive electrode and the negative electrode, comprises the electrode according to claim 8.

10. The energy storage device according to 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; When the energy storage device is a lithium ion secondary battery, the positive electrode 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 phosphate containing olivine structure, preferably LiFeMnPO4, LiCoO2, LiMn2O4, LiNiMnCoO2, 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, based on the dry weight of the positive electrode film, the amount of the positive electrode active material is 80-98% by weight, preferably 90-98% by weight, and / or The negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesophase microcarbon beads (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 composites and silicon alloys, preferably, based on the dry weight of the negative electrode film, the amount of the negative electrode active material is 80-98% by weight, preferably 90-98% by weight; 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 analogs, 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, based on the dry weight of the positive electrode film, the amount of the positive electrode active material is 80-98% by weight, preferably 90-98% by weight, and / or The negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesophase microcarbon beads (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 composites and silicon alloys, preferably, based on the dry weight of the negative electrode film, the amount of the negative electrode active material is 80-98% by weight, preferably 90-98% by weight; When the energy storage device is a lithium-sulfur secondary battery, the positive electrode active material is selected from lithium sulfide, titanium sulfide, phosphorus sulfide, or one or more compounds of organic compounds with linear alkyl, branched alkyl, cycloalkane, aromatic hydrocarbon, aromatic hydrocarbon containing heteroatom and sulfur, preferably one or more of sulfur-carbon composite positive electrode materials and sulfided polyacrylonitrile. Preferably, based on the dry weight of the positive electrode membrane, the amount of the positive electrode active material is 80-98% by weight, preferably 90-98% by weight, and / or The negative electrode active material is selected from metallic lithium, preferably, based on the dry weight of the negative electrode film, the amount of the negative electrode active material is 80-99 wt%, preferably 90-99 wt%; When the energy storage device is a capacitor, the positive electrode active material is selected from one or more of metal oxides, conductive polymers and carbon materials, preferably one or more of MnO2, NiO, Co3O4, polyaniline, polypyrrole, activated carbon, graphene and biochar, preferably, based on the dry weight of the positive electrode film, the amount of the positive electrode active material is 80-98% by weight, preferably 90-98% by weight, and / or The negative electrode active material is selected from one or more of metals, carbon materials, conductive polymers, metal oxides, and metal organic framework (MOF) derived materials, preferably one or more of aluminum, zinc, activated carbon, graphite, polyaniline, polypyrrole, polythiophene and MnO2. Preferably, based on the dry weight of the negative electrode membrane, the amount of the negative electrode active material is 80-98% by weight, preferably 90-98% by weight.

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