Electrode, energy storage device, electrode production system, and electrode production method

Abstract

The present application relates to an electrode comprising a current collector and a self-supporting electrode film, wherein the self-supporting electrode film comprises an electrode active material, a conductive agent, and a binder, the binder comprises at least 30% by weight of polyethylene and / or polypropylene based on the total dry weight of the binder, and the tensile strength of the self-supporting electrode film in the length direction is 0.15 MPa or more. The present application also relates to an energy storage device comprising the electrode, an electrode production system, and a preparation method of the electrode. The electrode of the present application or the electrode prepared by the electrode preparation method of the present application has excellent initial coulombic efficiency, high specific capacity, and excellent cycle performance.

Description

Technical Field

[0001] This invention generally relates to the field of electrochemical energy storage technology. Specifically, this invention relates to an electrode and an energy storage device including the electrode, as well as an electrode manufacturing system and a method for preparing the electrode. Background Technology

[0002] Polyethylene and / or polypropylene have a wide range of applications in packaging, construction, and household goods. In recent years, with the rapid development of new energy technologies, energy storage devices such as secondary batteries have received widespread attention. In energy storage devices such as secondary batteries, polyethylene and / or polypropylene are generally used to manufacture separators. Polyethylene separators possess good flexibility and elasticity, while polypropylene separators possess high stiffness, wear resistance, and impact resistance. However, in existing technologies, polyethylene and / or polypropylene are rarely used as binders in specific applications to bond electrode active materials, conductive agents, etc., to manufacture electrodes. One reason is that when polyethylene and / or polypropylene are used as binders, the resulting electrodes are difficult to meet the ever-increasing demands for electrochemical performance, such as initial coulombic efficiency, discharge specific capacity, and cycle performance.

[0003] Therefore, the development of a new electrode using polyethylene and / or polypropylene as a binder, which possesses excellent initial coulombic efficiency, high discharge specific capacity, and excellent cycle performance, is of great significance for meeting market demands. Summary of the Invention

[0004] This invention was made in view of the above-mentioned problems existing in the prior art.

[0005] In a first aspect, the present invention relates to an electrode comprising a current collector and a self-supporting electrode membrane, wherein the self-supporting electrode membrane comprises an electrode active material, a conductive agent, and a binder, the binder comprising at least 30% by weight, preferably at least 50% by weight, more preferably at least 60% by weight, and even more preferably at least 80% by weight, for example 80-100% by weight, of polyethylene and / or polypropylene based on the total dry weight of the binder, and the self-supporting electrode membrane having a tensile strength in the longitudinal direction of 0.15 MPa or more, for example 0.20 MPa or more, or 0.25 MPa or more, or 0.30 MPa or more.

[0006] When the electrode uses polyethylene and / or polypropylene as a binder, and the electrode film of the electrode has a tensile strength of more than 0.15 MPa in the length direction, the electrode can easily obtain excellent initial coulombic efficiency, high discharge specific capacity and excellent cycle performance.

[0007] In a second aspect, the present invention relates to an energy storage device comprising the electrodes described in the first aspect of the invention.

[0008] In a third aspect, the present invention relates to an electrode manufacturing system comprising:

[0009] (a) A feeding module for supplying electrode active materials, conductive agents and binders;

[0010] (b) A mixing module, located downstream of (a) the feeding module, is used to mix the electrode active material, conductive agent and binder;

[0011] (c) Preforming module, located downstream of (b) mixing module, is used to preform the mixture obtained from the mixing module to obtain a preformed self-supporting electrode film.

[0012] (d) Current collector supply module for supplying current collectors;

[0013] (e) A composite module, located downstream of (c) the preforming module and (d) the current collector supply module, is used to composite the preformed self-supporting electrode film and the current collector;

[0014] (f) An optional heat treatment module located between (c) the preforming module and (e) the composite module; and

[0015] (g) An optional temperature control module for displaying and controlling the temperature of (f) the heat treatment module.

[0016] In a fourth aspect, the present invention relates to a method for preparing an electrode, comprising:

[0017] Step (i): Provide electrode active material, conductive agent and binder, wherein the binder comprises at least 30% by weight, preferably at least 50% by weight, more preferably at least 60% by weight, and even more preferably at least 80% by weight, for example 80-100% by weight, of polyethylene and / or polypropylene based on the total dry weight of the binder;

[0018] Step (ii): Mix the electrode active material, conductive agent, and binder; and

[0019] Step (iii): Obtain the electrode from the mixture obtained in step (ii).

[0020] Step (iii) includes:

[0021] Step (iii-1): The mixture obtained in step (ii) is pre-formed to obtain a pre-formed self-supporting electrode film; and

[0022] Step (iii-2): Provide a current collector and composite the current collector with the pre-formed self-supporting electrode film obtained in the previous step.

[0023] And step (iii) includes a heat treatment process, wherein the heat treatment temperature T, in °C, is... v The melting point T of the adhesive (in °C) m satisfy: Preferred ,

[0024] The heat treatment process is performed during step (iii-1), or during step (iii-2), or independently of steps (iii-1) and (iii-2), for example, between steps (iii-1) and (iii-2).

[0025] In a fifth aspect, the present invention relates to an electrode prepared by an electrode preparation method according to a fourth aspect of the present invention.

[0026] The electrode preparation method of the present invention is simple to operate, the self-supporting electrode film of the obtained electrode has high tensile strength in the length direction, and the electrode has excellent initial coulombic efficiency, high discharge specific capacity and excellent cycle performance. Attached Figure Description

[0027] 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 purpose of facilitating a better understanding of the present invention by those skilled in the art, and are not intended to limit the scope of the present invention.

[0028] Figure 1 This is a schematic diagram of an electrode production system according to one embodiment of the present invention. Detailed Implementation

[0029] To make the inventive objectives, technical solutions, and beneficial technical effects of this application clearer, this application will be described in detail below. It should be noted that the various aspects, features, embodiments, and advantages described in this application can be compatible and / or combined together.

[0030] Unless otherwise specified, the technical terms used in this specification have the same meaning as commonly understood by those skilled in the art.

[0031] Unless otherwise specified in this application, the temperature is room temperature (25°C), the atmosphere is air, and the pressure is atmospheric pressure.

[0032] It should be noted that in this article, for a single binder such as linear low-density polyethylene, "the melting point T of the binder" is used. m "This refers to the melting point of the linear low-density polyethylene itself; for mixtures of various types of binders, such as mixtures of linear low-density polyethylene and polypropylene copolymers, "the melting point T of the binder..." m"This refers to the lower temperature at which the mixture undergoes a solid-liquid phase transition during the melting point determination. For example, if the binder mixture exhibits only one solid-liquid phase transition temperature during the melting point determination, then that temperature is the "melting point T of the binder." m "If the binder mixture exhibits multiple solid-liquid phase transition temperatures during melting point determination, then the lowest of these temperatures is the melting point T of the binder." m In this application, the melting point can be measured by methods conventionally used in the art, such as differential scanning calorimetry (DSC).

[0033] Unless otherwise specified, the term "high temperature" in this document means a temperature above room temperature, such as 50-200°C, such as 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200°C, or any two of these.

[0034] The present invention relates to an electrode and an energy storage device including the electrode, as well as an electrode manufacturing system and a method for preparing the electrode.

[0035] The present invention will be described in detail below.

[0036] electrode

[0037] A first aspect of the present invention provides an electrode comprising a current collector and a self-supporting electrode membrane, wherein the self-supporting electrode membrane comprises an electrode active material, a conductive agent, and a binder, the binder comprising at least 30% by weight, preferably at least 50% by weight, more preferably at least 60% by weight, and even more preferably at least 80% by weight, for example 80-100% by weight, of polyethylene and / or polypropylene based on the total dry weight of the binder, and the self-supporting electrode membrane having a tensile strength in the longitudinal direction of 0.15 MPa or more, for example 0.20 MPa or more, or 0.25 MPa or more, or 0.30 MPa or more.

[0038] When the electrode uses polyethylene and / or polypropylene as a binder, and the electrode film of the electrode has a tensile strength of more than 0.15 MPa in the length direction, the electrode can easily obtain excellent initial coulombic efficiency, high discharge specific capacity and excellent cycle performance.

[0039] For example, the tensile strength of the self-supporting electrode film in the length direction may be, for example, 0.15-0.50 MPa or 0.25-0.50 MPa, such as within the range defined by 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50 MPa, or any two of them. In this application, tensile strength can be measured by methods conventionally used in the art, such as using a small-tonnage mechanical tensile testing machine.

[0040] In the electrode of the present invention, the binder comprises polyethylene and / or polypropylene, and the total content of polyethylene and polypropylene (i.e., the content of polyethylene when polypropylene is absent, the content of polypropylene when polyethylene is absent, and the total content of both when both polyethylene and polypropylene are present) is at least 30% by weight, preferably at least 50% by weight, more preferably at least 60% by weight, and even more preferably at least 80% by weight, for example, 80-100% by weight; for example, it may be within the range defined by 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100% by weight, or any two of them.

[0041] In some embodiments, the adhesive comprises polyethylene, and the polyethylene content may be 50-100%, preferably 80-100%, based on the total dry weight of the adhesive, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100% by weight, or within the range defined by any two of these.

[0042] In some embodiments, the adhesive comprises polypropylene, such as chlorinated polypropylene, and the content of polypropylene, such as chlorinated polypropylene, may be 50-100%, preferably 80-100%, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100% by weight, or within the range defined by any two of them.

[0043] In some embodiments, the adhesive comprises no more than 50% by weight of polytetrafluoroethylene based on the total dry weight of the adhesive.

[0044] While adding polytetrafluoroethylene (PTFE) to binders can improve tensile strength, the decomposition of PTFE during battery applications can cause numerous problems. In this document, the PTFE content is no more than 50% by weight, for example, no more than 45% by weight, no more than 40% by weight, no more than 35% by weight, no more than 30% by weight, no more than 25% by weight, no more than 20% by weight, no more than 15% by weight, no more than 10% by weight, no more than 5% by weight, or no more than 2% by weight. In some embodiments, the binder used in this invention does not contain PTFE.

[0045] In some embodiments, the adhesive is composed of polyethylene and / or polypropylene.

[0046] In some embodiments, at least a portion of the polyethylene and / or polypropylene forms fibers. The term "forms fibers" refers to the presence of a fibrous structure in the electrode cross-section, which can be determined by scanning electron microscopy.

[0047] In some embodiments, at least a portion of the polyethylene and / or polypropylene is formed into fibers, and the formed fibers are in the thickness direction of the self-supporting electrode film. Within 45°, for example Within 30°, for example Oriented fibers with an orientation of less than 15°. The term "oriented fiber" refers to fibers formed from polyethylene and / or polypropylene whose overall orientation is along the thickness direction of the self-supporting electrode film. Within 45°, for example Within 30°, for example Fibers oriented within 15°. This excludes fibers formed from, for example, polyethylene and / or polypropylene, where only a portion satisfies the defined orientation but the fiber as a whole does not. Not wishing to be limited by any theory, it is believed that when at least a portion of the polyethylene and / or polypropylene forms fibers and the formed fibers are oriented fibers with a defined orientation, it is beneficial to improve the mechanical strength of the self-supporting electrode film and to improve electrochemical performance such as initial coulombic efficiency, discharge specific capacity, and cycle performance. For example, the (overall) orientation of the oriented fibers may be in the thickness direction of the self-supporting electrode film. 45° 40° 35° 30° 25° 20° 15° 10° Within 5°. The overall orientation of fibers formed from polyethylene and / or polypropylene can be observed, for example, by means of an electron microscope, such as a scanning electron microscope, to observe cross-sections.

[0048] The present invention does not have any particular requirement for the total amount of adhesive used, and amounts conventionally used in the art can be used. For example, the total weight of the adhesive accounts for 1-10% by weight of the total dry weight of the self-supporting electrode film, for example, 1-5% by weight.

[0049] In some embodiments, the polyethylene is selected from one or more of ultra-high molecular weight polyethylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, and linear low-density polyethylene, preferably linear low-density polyethylene.

[0050] In some embodiments, the melting point of the polyethylene is in the range of 85-150°C, preferably 110-140°C. The melting point can be determined by conventional measurement methods in the art. For example, the melting point can be determined by differential scanning calorimetry (DSC).

[0051] In some embodiments, the glass transition temperature of the polyethylene is -120°C to -70°C, preferably -120°C to -90°C. The glass transition temperature can be determined by conventional measurement methods in the art. For example, the glass transition temperature can be determined by differential scanning calorimetry (e.g., according to ASTM D3418-2015).

[0052] In some embodiments, the polyethylene has a melt index ranging from 0.1 to 100 g / 10 min, preferably 10 to 30 g / 10 min, as measured according to ISO 1133-1:2022 at a temperature of 190°C and a load of 2.16 kg.

[0053] In some embodiments, the polypropylene is selected from one or more of polypropylene homopolymers and polypropylene copolymers, such as chlorinated polypropylene.

[0054] In some embodiments, the melting point of the polypropylene is in the range of 105-180°C, preferably 120-150°C. As mentioned above, the melting point can be determined by differential scanning calorimetry.

[0055] In some embodiments, the glass transition temperature of the polypropylene is -20°C to 10°C. As previously mentioned, the glass transition temperature can be determined by differential scanning calorimetry, for example, according to ASTM D3418-2015.

[0056] In some embodiments, the polypropylene has a melt index ranging from 0.3 to 100 g / 10 min, preferably 1 to 20 g / 10 min, as measured according to ISO 1133-1:2022 at a temperature of 230°C and a load of 2.16 kg.

[0057] In this invention, in addition to polyethylene / polypropylene, the adhesive may also include one or more of the following: polytetrafluoroethylene, polyacrylic acid, sodium carboxymethyl cellulose, polyvinylidene fluoride and its derivatives, polyvinyl butyral, styrene-butadiene rubber, polyvinyl alcohol, sodium alginate, polyimide, polylactic acid, polyisobutylene, polystyrene, polycaprolactone, polycarbonate, polyamide, poly-L-lactic acid, polyolefin copolymer, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene adipamide (polyhexamethylene adipamide), ethylene acrylate copolymer, polyvinyl acetate, polyurethane, epoxy resin, chitosan, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene propylene copolymer, polylactic acid-glycolic acid copolymer, epoxy acrylate, ethylene-vinyl acetate copolymer, polyoxymethylene, polyphenylene sulfide, paraffin wax, gelatin, and beeswax.

[0058] In some embodiments, the content of the binder other than polyethylene / polypropylene is 0-50% by weight, preferably 0-20% by weight, based on the total dry weight of the binder. For example, the content of the binder other than polyethylene / polypropylene may be 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50% by weight, or within the range defined by any two of these. As an example, in addition to polyethylene / polypropylene, the binder may also include, for example, 0-50% by weight of polyacrylic acid; for example, in addition to polyethylene / polypropylene, the binder may also include, for example, up to 50% by weight of polytetrafluoroethylene; for example, in addition to polyethylene / polypropylene, the binder may also include, for example, 0-50% by weight of sodium carboxymethyl cellulose.

[0059] This invention does not impose any particular requirements on the type and content of the electrode active material; electrode active materials of the types and amounts conventionally used in the art can be used. For example, the electrode active material can be any of the various electrode active materials described below in the "Energy Storage Devices" section. For example, based on the total dry weight of the self-supporting electrode film, the amount of the electrode active material can be 70-99% by weight, for example, 80-95% by weight.

[0060] This invention does not impose any particular requirements on the conductive agent used; any type of conductive agent conventionally used in the art can be used. As an example, the conductive agent may be selected from one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. Furthermore, as an example, based on the total dry weight of the self-supporting electrode film, the amount of the conductive agent may be 0.5-15.0% by weight, for example, 2.0-5.0% by weight.

[0061] Energy storage devices

[0062] A second aspect of the present invention provides an energy storage device comprising the electrodes described in the first aspect of the present invention.

[0063] The electrode may be the positive electrode and / or negative electrode of the energy storage device.

[0064] In some embodiments, the energy storage device may be a lithium-ion secondary battery. For lithium-ion secondary batteries, the positive electrode active material may be, for example, 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 phosphates with an olivine structure, preferably. , , , , , , and One or more of the following; the negative electrode active material may be selected, for example, from one or more of natural graphite, artificial graphite, mesophase micro carbon spheres (MCMB), hard carbon, soft carbon, silicon-based materials, tin-based materials, lithium titanate and lithium metal, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composites and silicon alloys.

[0065] In some embodiments, the energy storage device may be a sodium-ion secondary battery. For sodium-ion secondary batteries, the positive electrode active material may be selected, for example, one or more of layered transition metal oxides or Prussian blue analogues, preferably... , , , , and One or more of the following; the negative electrode active material may be selected, for example, from one or more of natural graphite, artificial graphite, mesophase micro carbon spheres (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.

[0066] In some embodiments, the energy storage device may be a supercapacitor. For supercapacitors, the positive electrode active material may be selected from one or more of metal oxides, conductive polymers, and carbon materials, preferably... NiO One or more of polyaniline, polypyrrole, activated carbon, graphene, and biochar; the negative electrode active material may be selected, for example, one or more of metals, carbon materials, conductive polymers, metal oxides, and metal-organic framework (MOF) derived materials, preferably aluminum, zinc, activated carbon, graphite, polyaniline, polypyrrole, polythiophene, and... One or more of them.

[0067] In this invention, energy storage devices can be fabricated by assembling various components, including the electrodes of this invention or electrodes prepared by the electrode preparation method of this invention, according to methods conventionally used in the art. For example, taking a secondary battery as an example, the positive electrode, the negative electrode, and the separator located between them can be assembled by conventional methods in the art, and then an electrolyte is injected, followed by sealing and other processes to obtain the device, which will not be described in detail here.

[0068] This invention does not have any particular requirements on the type of diaphragm, and any diaphragm conventionally used in the art can be used. For example, the material of the diaphragm can be selected from one or more of polyethylene, polypropylene, polyethylene terephthalate, polyimide, polyamide, and poly(p-phenylene terephthalamide); the diaphragm can be a single-layer membrane or a multi-layer membrane; the diaphragm can optionally be surface modified (e.g., modified on a single surface or two surfaces), for example, by coating with a ceramic layer.

[0069] This invention does not have any particular requirements regarding the type of electrolyte; any electrolyte type conventionally used in the art can be used. As an example, a lithium-ion secondary battery will be used as an example in the following description.

[0070] For lithium-ion secondary batteries, the electrolyte may be a non-aqueous liquid electrolyte, which includes an organic solvent and an electrolyte lithium salt.

[0071] In some embodiments, the organic solvent may be selected from one or more of ethylene carbonate (EC), vinylene carbonate (VC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0072] In some embodiments, the electrolyte lithium salt may be selected from lithium hexafluorophosphate (LiPF6). Lithium tetrafluoroborate () ), lithium perchlorate ( Lithium hexafluoroborate () Lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate ( One or more of lithium difluorodioxanol phosphate (LiDFOP) and lithium tetrafluorooxanol phosphate (LiTFOP).

[0073] In some embodiments, the concentration of lithium ions in the non-aqueous liquid electrolyte is 0.5-1.5 mol / L, for example 0.8-1.2 mol / L.

[0074] In some embodiments, the non-aqueous liquid electrolyte may optionally include additives. As an example, the additives may include those that facilitate film formation on the negative electrode or the positive electrode, and may also include additives that improve battery performance, such as those that improve the battery's high-temperature or low-temperature performance.

[0075] For lithium-ion secondary batteries, the electrolyte can also be a gel electrolyte or a solid electrolyte, which will not be elaborated here.

[0076] Electrode production system

[0077] A third aspect of the present invention provides an electrode production system comprising:

[0078] (a) A feeding module for supplying electrode active materials, conductive agents and binders;

[0079] (b) A mixing module, located downstream of (a) the feeding module, is used to mix the electrode active material, conductive agent and binder;

[0080] (c) Preforming module, located downstream of (b) mixing module, is used to preform the mixture obtained from the mixing module to obtain a preformed self-supporting electrode film.

[0081] (d) Current collector supply module for supplying current collectors;

[0082] (e) A composite module, located downstream of (c) the preforming module and (d) the current collector supply module, is used to composite the preformed self-supporting electrode film and the current collector;

[0083] (f) An optional heat treatment module located between (c) the preforming module and (e) the composite module; and

[0084] (g) An optional temperature control module for displaying and controlling the temperature of (f) the heat treatment module.

[0085] Figure 1 This is a schematic diagram illustrating one embodiment of the electrode production system of the present invention. See also... Figure 1The electrode production system of the present invention includes a feeding module 100, a mixing module 200, a preforming module 301, an optional heat treatment module 302, a current collector supply module 401, a composite module 501, and an optional temperature control module (not shown). In a typical embodiment, the feeding module 100 supplies electrode active material, conductive agent, and binder to the mixing module 200; the mixing module mixes the supplied raw materials and then conveys the mixed mixture to the preforming module 301 via a conveying device for rolling to produce a preformed self-supporting electrode film; then it is conveyed to the optional heat treatment module 302 via a conveying device for heat treatment; after the heat treatment module heat-treats the preformed self-supporting electrode film, it is conveyed to the composite module 501 via a conveying device to composite the preformed self-supporting electrode film with the current collector from the current collector supply module 401, thereby obtaining an electrode.

[0086] In the electrode production system of the present invention, the heat treatment module can perform heat treatment by means of (high temperature) standing, (high temperature) rolling or (high temperature) hot pressing. Figure 1 The diagram schematically illustrates heat treatment module 302 performed by (high-temperature) rolling, for example, double-roll rolling, wherein the temperature of the upper roll is preferably equal to the temperature of the lower roll. Alternatively, heat treatment module 302 may also be performed by (high-temperature) standing or (high-temperature) hot pressing. For operational details of heat treatment module 302, please refer to the description below in the electrode preparation method.

[0087] Those skilled in the art will readily understand that, in addition to the modules described above, the electrode production system of the present invention may optionally include other modules, such as a slitting module (not shown), for slitting the produced electrodes. Those skilled in the art can make conventional settings as needed, which will not be elaborated upon here.

[0088] The electrode production system of the present invention has the advantages of simple process, high production efficiency, low energy consumption, no pollution, and can be easily combined with commonly used production equipment in the prior art, which is conducive to realizing continuous and large-scale production.

[0089] Electrode preparation method

[0090] A fourth aspect of the present invention provides a method for preparing an electrode, comprising:

[0091] Step (i): Provide electrode active material, conductive agent and binder, wherein the binder comprises at least 30% by weight, preferably at least 50% by weight, more preferably at least 60% by weight, and even more preferably at least 80% by weight, for example 80-100% by weight, of polyethylene and / or polypropylene based on the total dry weight of the binder;

[0092] Step (ii): Mix the electrode active material, conductive agent, and binder; and

[0093] Step (iii): Obtain the electrode from the mixture obtained in step (ii).

[0094] Step (iii) includes:

[0095] Step (iii-1): The mixture obtained in step (ii) is pre-formed to obtain a pre-formed self-supporting electrode film; and

[0096] Step (iii-2): Provide a current collector and composite the current collector with the pre-formed self-supporting electrode film obtained in the previous step.

[0097] And step (iii) includes a heat treatment process, wherein the heat treatment temperature T, in °C, is... v The melting point T of the adhesive (in °C) m satisfy: Preferred ,

[0098] The heat treatment process is performed during step (iii-1), or during step (iii-2), or independently of steps (iii-1) and (iii-2), for example, between steps (iii-1) and (iii-2).

[0099] The electrode preparation method of the present invention is simple to operate, the self-supporting electrode film of the obtained electrode has high tensile strength in the length direction, and the electrode has excellent initial coulombic efficiency, high discharge specific capacity and excellent cycle performance.

[0100] The following will describe each step of the electrode preparation method of the present invention.

[0101] Step (i)

[0102] Step (i) provides electrode active material, conductive agent and binder.

[0103] For the types and amounts of electrode active materials, conductive agents, and binders, please refer to the description above, which will not be repeated here.

[0104] It should be noted that, as will be readily understood by those skilled in the art, during the preparation of the self-supporting electrode film, various additives commonly used in the art, such as thickeners and film-forming accelerators, may be added as needed.

[0105] Step (ii)

[0106] Step (ii) involves mixing the electrode active material, conductive agent, and binder to prepare for subsequent steps.

[0107] The electrode preparation method of the present invention does not have special requirements for the mixing method, and can adopt the mixing methods commonly used in the art, such as mixing by one or more of stirring, ball milling, jet milling, high-speed shearing, or mechanical grinding. As an example, those skilled in the art can mix by using a planetary ball mill or mechanical stirring. For example, when mixing by mechanical stirring, the stirring speed can be controlled to be within the range of 50-10000 rpm, such as 50 rpm, 100 rpm, 300 rpm, 500 rpm, 1000 rpm, 2000 rpm, 3000 rpm, 5000 rpm, 8000 rpm, 10000 rpm, or any two of these ranges, and / or the mixing time can be within the range of 5-720 minutes, such as 5 minutes, 30 minutes, 60 minutes, 120 minutes, 240 minutes, 300 minutes, 360 minutes, 420 minutes, 720 minutes, or any two of these ranges. In addition, for example, zirconium oxide can be used as the ball milling media, with the zirconium oxide volume percentage being less than 30%.

[0108] Step (iii)

[0109] In step (iii), an electrode is obtained from the mixture obtained in step (ii), wherein step (iii) includes:

[0110] Step (iii-1): The mixture obtained in step (ii) is pre-formed to obtain a pre-formed self-supporting electrode film; and

[0111] Step (iii-2): Provide a current collector and composite the current collector with the pre-formed self-supporting electrode film obtained in the previous step.

[0112] And step (iii) includes a heat treatment process, wherein the heat treatment temperature T, in °C, is... v The melting point T of the adhesive (in °C) m satisfy: Preferred ,

[0113] The heat treatment process is performed during step (iii-1), or during step (iii-2), or independently of steps (iii-1) and (iii-2), for example, between steps (iii-1) and (iii-2).

[0114] In some embodiments, step (iii-1) is performed by roller pressing. Preferably, during roller pressing, the temperature of the lower roller is set in the range of 100-180°C, and the temperature of the upper roller is set in the range of 100-160°C. Preferably, the temperature of the upper roller is equal to the temperature of the lower roller. As an example, the temperature of the lower roller may be within the range of 100, 110, 120, 130, 140, 150, 160, 170, 180°C, or any two of them, and the temperature of the upper roller may be within the range of 100, 110, 120, 130, 140, 150, 160°C, or any two of them. Other details regarding roller pressing can be obtained by those skilled in the art as needed by referring to conventional methods in the art, and will not be elaborated here.

[0115] The present invention does not have special requirements for the composite method in step (iii-2), and composite methods commonly used by those skilled in the art can be adopted. For example, composite can be performed by roller pressing, such as roller pressing with two rollers. When composite is performed by roller pressing with two rollers, it is preferable to place the current collector close to the lower roller and the self-supporting electrode film close to the upper roller, and the temperature of the lower roller is higher than or equal to the temperature of the upper roller. For example, the temperature of the lower roller can be in the range of 100-180°C, and / or the temperature of the upper roller can be in the range of 70-150°C. For example, the temperature of the lower roller can be in the range of 100, 100, 110, 120, 130, 140, 150, 160, 170, 180°C, or any two of them, and / or the temperature of the upper roller can be in the range of 70, 80, 90, 100, 110, 120, 130, 140, 150°C, or any two of them.

[0116] When the heat treatment process is carried out during step (iii-1) or step (iii-2), if the upper and lower rollers used have different temperatures, the heat treatment temperature refers to the temperature of the roller with the higher temperature, such as the temperature of the lower roller.

[0117] Alternatively, the current collector can be sputtered onto the self-supporting electrode film by magnetron sputtering. Alternatively, the current collector can be electrodeposited onto the self-supporting electrode film by electrodeposition. Magnetron sputtering and electrodeposition can be performed in ways commonly used by those skilled in the art, and will not be described in detail here.

[0118] This invention does not have any particular requirements for the type of current collector; commonly used current collector types in the art can be used. For example, for the positive electrode, aluminum foil, nickel foil, or composite current collectors can be used; for the negative electrode, copper foil or composite current collectors can be used.

[0119] The inventors discovered in their research that when step (iii) includes a heat treatment process, and the heat treatment temperature T in °C is... vThe melting point T of the adhesive (in °C) m satisfy When the self-supporting electrode film of the electrode prepared by the method of the present invention has high tensile strength in the length direction, the electrode has excellent initial coulombic efficiency, high discharge specific capacity, and excellent cycle performance. Furthermore, when the heat treatment temperature T (in °C) of this heat treatment process... v The melting point T of the adhesive (in °C) m satisfy At this time, the tensile strength of the self-supporting electrode film of the obtained electrode in the longitudinal direction is further increased, and the initial coulombic efficiency, discharge specific capacity, and cycle performance of the electrode are also further improved. For example, in some embodiments, T v It may be within the following ranges: 100, 110, 120, 130, 140, 150, 160, 170, 180°C, or any two of them.

[0120] In a preferred embodiment, the heat treatment process may be performed independently of steps (iii-1) and (iii-2), for example, between steps (iii-1) and (iii-2).

[0121] In some embodiments, the heat treatment process can be carried out by standing, rolling, or hot pressing.

[0122] In some embodiments, the heat treatment process is carried out by static settling, and the heat treatment temperature T is measured in °C. v The resting time t1, measured in hours, satisfies: .

[0123] The inventors discovered through research that, when the heat treatment process is carried out by static standing, the heat treatment temperature T (in °C) v The resting time t1 in hours satisfies At that time, compared to the heat treatment temperature T v For electrodes whose resting time t1 does not satisfy the above correlation, the tensile strength of the self-supporting electrode film in the longitudinal direction is increased, and the initial coulombic efficiency, discharge specific capacity, and cycle performance of the electrode are also improved. For example, the resting time t1 in hours can be within the range defined by any two of the following: , ,or .

[0124] In some embodiments, the heat treatment process is carried out by rolling, and the heat treatment temperature T is expressed in °C. v The rolling time t2, measured in seconds, satisfies: Preferred .

[0125] Similarly, the inventors discovered through research that when the heat treatment process is carried out by rolling, for example by pressing against a roller, when the heat treatment temperature T is in °C... v The rolling time t2, measured in seconds, satisfies At that time, compared to the heat treatment temperature T v For electrodes whose rolling time t2 does not satisfy the above correlation, the tensile strength of the self-supporting electrode film in the length direction is increased, and the initial coulombic efficiency, discharge specific capacity, and cycle performance of the electrode are also improved. When the heat treatment temperature T (in °C) v The rolling time t2, measured in seconds, satisfies At this time, the tensile strength of the self-supporting electrode film of the obtained electrode in the length direction is further increased, and the initial coulombic efficiency, discharge specific capacity and cycle performance of the electrode are also further improved. Furthermore, let... , , Then the rolling time t2, measured in seconds, can be within the range defined by any two of the following: For example, A, , , , , , , , , 、 or B.

[0126] In some embodiments, the heat treatment process is carried out by pressing the rollers together, preferably with the upper roller temperature being equal to the lower roller temperature.

[0127] In some embodiments, the heat treatment process is carried out by hot pressing, and the heat treatment temperature T is measured in °C. v The hot pressing time t3, measured in minutes, satisfies: .

[0128] Similarly, the inventors discovered through research that when the heat treatment process is carried out by hot pressing, when the heat treatment temperature T (in °C) v The hot pressing time t3, measured in minutes, satisfies: At that time, compared to the heat treatment temperature T v For electrodes whose hot-pressing time t3 does not satisfy the above correlation, the tensile strength of the self-supporting electrode film in the longitudinal direction is increased, and the initial coulombic efficiency, discharge specific capacity, and cycle performance of the electrode are also improved. Further, let... , , Then the hot pressing time t3, in minutes, can be within the range defined by any two of the following: For example, C, , , , , , , , , 、 or D.

[0129] In some embodiments, the heat treatment process is carried out by hot pressing, and the pressure of the heat treatment process is 5-20 MPa. For example, the pressure of the heat treatment process may be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 MPa, or within the range defined by any two of them.

[0130] In an embodiment, when the heat treatment process is performed, for example by standing, rolling, or hot pressing, the self-supporting electrode film can be placed horizontally. When the heat treatment process is performed before step (iii-2), in step (iii-2), the lower surface of the self-supporting electrode film during the standing, rolling, or hot pressing process can be combined with the surface of the current collector.

[0131] In this embodiment, when performing roller pressing, the number of pressing cycles can be those conventionally used by those skilled in the art, such as 1-20 times or 2-10 times, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 times, or any two of these ranges.

[0132] Regarding the binders used in the preparation method of the present invention, such as polyethylene and polypropylene, and the electrode materials, such as electrode active materials, please refer to the description in the electrode section above, and will not be repeated here.

[0133] electrode

[0134] The fifth aspect of the present invention also provides an electrode prepared by the preparation method of the fourth aspect of the present invention.

[0135] All descriptions above relating to the fourth aspect of the invention are applicable here and will not be repeated here.

[0136] Example

[0137] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0138] Preparation Examples

[0139] Example 1

[0140] Preparation of positive electrode

[0141] (1) NCM523 (Clude, Super P (conductive carbon black), linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918 g / cm³), and Super P (conductive carbon black), linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918 g / cm³). 3 (Glass transition temperature -120℃, melt index 12 g / 10min) are mixed evenly at a mass ratio of 93:3:4.

[0142] (2) Roll the mixture obtained in (1) (the rolling method is hot rolling, the temperature of the upper roller is 100℃, the temperature of the lower roller is 100℃, and the rolling time is 60 seconds) to obtain a pre-formed self-supporting electrode film.

[0143] (3) The preformed self-supporting electrode film obtained in (2) was left to stand under vacuum at 100°C for 5 hours.

[0144] (4) The self-supporting electrode film obtained in (3) is combined with aluminum foil through a roller pressing method during the static process in step (3) by the lower surface of the film and the roller pressing time is 30 seconds to obtain the positive electrode.

[0145] Preparation of negative electrode

[0146] (1) Gr (graphite), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918 g / cm³) were added. 3 Mix them evenly at a mass ratio of 95:2.5:2.5 (glass transition temperature -120℃, melt index 12 g / 10min).

[0147] (2) Roll the mixture obtained in (1) (the rolling method is hot rolling, the temperature of the upper roller is 100℃, the temperature of the lower roller is 100℃, and the rolling time is 60 seconds) to obtain a pre-formed self-supporting electrode film.

[0148] (3) The preformed self-supporting electrode film obtained in (2) was left to stand under vacuum at 100°C for 5 hours.

[0149] (4) The self-supporting electrode film obtained in (3) is combined with copper foil through a roller pressing method during the static process in step (3) to obtain a negative electrode.

[0150] Note: Melting point was measured using a differential scanning calorimeter (manufacturer: TA INSTRUMENTS, model: Q5000IR) under the following conditions: nitrogen atmosphere, heating rate 10℃ / min, and test temperature range from room temperature to 200℃. The solid-liquid phase transition temperatures during the test were recorded, and the lowest solid-liquid phase transition temperature was taken as the melting point of the binder.

[0151] Melt index: The melt index of polyethylene was determined according to ISO 1133-1:2022 at a temperature of 190°C and a load of 2.16 kg; the melt index of polypropylene was determined according to ISO 1133-1:2022 at a temperature of 230°C and a load of 2.16 kg.

[0152] Glass transition temperature: According to ASTM D3418-2015, the temperature was increased from -120°C to 25°C at a heating rate of 10°C / min using differential scanning calorimetry, held at that temperature for 1 hour, and then decreased to -120°C at a cooling rate of 10°C / min. A second heating process was then performed, increasing the temperature from -120°C to 25°C at a heating rate of 10°C / min, holding at that temperature for 1 hour, and then decreasing to -120°C at a cooling rate of 10°C / min.

[0153] Example 2

[0154] Except for changing the settling temperature in step (3) of the positive and negative electrode preparation process to 120°C, the rest is the same as in Example 1.

[0155] Example 3

[0156] Except for changing the standing temperature to 180°C and the standing time to 2.56 hours in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 1.

[0157] Example 4

[0158] Except for changing the standing temperature to 160°C and the standing time to 2.56 hours in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 1.

[0159] Example 5

[0160] Preparation of positive electrode

[0161] (1) NCM523 (Kelode, MA-EN-CA-0020), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918g / cm³) were added. 3 (Glass transition temperature -120℃, melt index 12 g / 10min) are mixed evenly at a mass ratio of 93:3:4.

[0162] (2) Roll the mixture obtained in (1) (the rolling method is hot rolling, the temperature of the upper roller is 100℃, the temperature of the lower roller is 100℃, and the rolling time is 60 seconds) to obtain a pre-formed self-supporting electrode film.

[0163] (3) In addition, the preformed self-supporting electrode film obtained in (2) is subjected to roller pressing, wherein the temperature of the upper roller is 100°C, the temperature of the lower roller is 100°C, and the pressing time is 260 seconds.

[0164] (4) The product obtained in (3) is combined with aluminum foil on the lower surface during the rolling process in step (3) by rolling (the upper roller temperature is 80°C, the lower roller temperature is 150°C, and the rolling time is 30 seconds) to obtain the positive electrode.

[0165] Preparation of negative electrode

[0166] (1) Gr (graphite), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918 g / cm³) were added. 3 Mix them evenly at a mass ratio of 95:2.5:2.5 (glass transition temperature -120℃, melt index 12 g / 10min).

[0167] (2) Roll the mixture obtained in (1) (the rolling method is hot rolling, the temperature of the upper roller is 100℃, the temperature of the lower roller is 100℃, and the rolling time is 60 seconds) to obtain a pre-formed self-supporting electrode film.

[0168] (3) In addition, the preformed self-supporting electrode film obtained in (2) is subjected to roller pressing, wherein the temperature of the upper roller is 100°C, the temperature of the lower roller is 100°C, and the pressing time is 260 seconds.

[0169] (4) The self-supporting electrode film obtained in (3) is combined with the copper foil through the rolling process in step (3) by rolling the lower surface with the copper foil (where the temperature of the upper roller is 80°C, the temperature of the lower roller is 150°C, and the rolling time is 30 seconds) to obtain the negative electrode.

[0170] Example 6

[0171] Except for changing the heat treatment temperature (i.e. the temperature of the upper and lower rollers of the roller pressing process, the same below) in step (3) of the positive and negative electrode preparation process to 120°C, the rest is the same as in Example 5.

[0172] Example 7

[0173] Except for changing the heat treatment temperature in step (3) of the positive and negative electrode preparation process to 120°C and the rolling time to 240 seconds, the rest is the same as in Example 5.

[0174] Example 8

[0175] Except for changing the heat treatment temperature in step (3) of the positive and negative electrode preparation process to 180°C and the rolling time to 93 seconds, the rest is the same as in Example 5.

[0176] Example 9

[0177] Except for changing the heat treatment temperature in step (3) of the positive and negative electrode preparation process to 180°C and the rolling time to 73 seconds, the rest is the same as in Example 5.

[0178] Example 10

[0179] Except for changing the heat treatment temperature in step (3) of the positive and negative electrode preparation process to 160°C and the rolling time to 93 seconds, the rest is the same as in Example 5.

[0180] Example 11

[0181] (1) NCM523 (Kelode, MA-EN-CA-0020), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918g / cm³) were added. 3 Glass transition temperature -120℃, melt index 12 g / 10min) and PTFE (Daikin F-104, Japan, melting point 344℃, density 2.18 g / cm³). 3 Mix them evenly in a mass ratio of 93:3:2:2, wherein the melting point of the binder mixture is 130℃.

[0182] (2) Roll the mixture obtained in (1) (the rolling method is hot rolling, the temperature of the upper roller is 100℃, the temperature of the lower roller is 100℃, and the rolling time is 60 seconds) to obtain a pre-formed self-supporting electrode film.

[0183] (3) The preformed self-supporting electrode film obtained in (2) was left to stand under vacuum at 100°C for 5 hours.

[0184] (4) The self-supporting electrode film obtained in (3) is combined with aluminum foil on the lower surface during the static process in step (3) by rolling with rollers (where the temperature of the upper roller is 80°C, the temperature of the lower roller is 150°C, and the rolling time is 30 seconds) to obtain the positive electrode.

[0185] Preparation of negative electrode

[0186] (1) Gr (graphite), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918 g / cm³) were added. 3Glass transition temperature -120℃, melt index 12 g / 10min) and PTFE (Daikin F-104, Japan, melting point 344℃, density 2.18 g / cm³). 3 Mix them thoroughly at a mass ratio of 95: 2.5: 1.5: 1, wherein the melting point of the binder mixture is 130℃.

[0187] (2) Roll the mixture obtained in (1) (the rolling method is hot rolling, the temperature of the upper roller is 100℃, the temperature of the lower roller is 100℃, and the rolling time is 60 seconds) to obtain a pre-formed self-supporting electrode film.

[0188] (3) The preformed self-supporting electrode film obtained in (2) was left to stand under vacuum at 100°C for 5 hours.

[0189] (4) The self-supporting electrode film obtained in (3) is combined with copper foil through a roller pressing method during the static process in step (3) to obtain a negative electrode.

[0190] Example 12

[0191] Except for changing the standing temperature to 180°C and the standing time to 2.56h during the preparation of the positive and negative electrodes, the rest is the same as in Example 11.

[0192] Example 13

[0193] Preparation of positive electrode

[0194] (1) NCM523 (Kelode, MA-EN-CA-0020), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918g / cm³) were added. 3 Glass transition temperature -120℃, melt index 12 g / 10min) and PTFE (Daikin F-104, Japan, melting point 344℃, density 2.18 g / cm³). 3 Mix them evenly in a mass ratio of 93:3:2:2, wherein the melting point of the binder mixture is 130℃.

[0195] (2) Roll the mixture obtained in (1) (the rolling method is hot rolling, the temperature of the upper roller is 100℃, the temperature of the lower roller is 100℃, and the rolling time is 60 seconds) to obtain a pre-formed self-supporting electrode film.

[0196] (3) In addition, the preformed self-supporting electrode film obtained in (2) is subjected to roller pressing, wherein the temperature of the upper roller is 160°C, the temperature of the lower roller is 160°C, and the pressing time is 93 seconds.

[0197] (4) The self-supporting electrode film obtained in (3) is combined with aluminum foil by means of rolling the lower surface of the film with the rollers in step (3) (where the temperature of the upper roller is 80°C, the temperature of the lower roller is 150°C, and the rolling time is 30 seconds) to obtain the positive electrode.

[0198] Preparation of negative electrode

[0199] (1) Gr (graphite), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918 g / cm³) were added. 3 Glass transition temperature -120℃, melt index 12 g / 10min) and PTFE (Daikin F-104, Japan, melting point 344℃, density 2.18 g / cm³). 3 Mix them thoroughly at a mass ratio of 95: 2.5: 1.5: 1, wherein the melting point of the binder mixture is 130℃.

[0200] (2) Roll the mixture obtained in (1) (the rolling method is hot rolling, the temperature of the upper roller is 100℃, the temperature of the lower roller is 100℃, and the rolling time is 60 seconds) to obtain a pre-formed self-supporting electrode film.

[0201] (3) In addition, the preformed self-supporting electrode film obtained in (2) is subjected to roller pressing, wherein the temperature of the upper roller is 160°C, the temperature of the lower roller is 160°C, and the pressing time is 93 seconds.

[0202] (4) The self-supporting electrode film obtained in (3) is combined with the copper foil through the rolling process in step (3) by rolling the lower surface with the copper foil (where the temperature of the upper roller is 80°C, the temperature of the lower roller is 150°C, and the rolling time is 30 seconds) to obtain the negative electrode.

[0203] Example 14

[0204] Except for changing the standing time in step (3) of the positive and negative electrode preparation process to 3.25 hours, the rest is the same as in Example 4.

[0205] Example 15

[0206] Except for changing the standing time in step (3) of the positive and negative electrode preparation process to 1.25 hours, the rest is the same as in Example 4.

[0207] Example 16

[0208] Except for changing the standing time in step (3) of the positive and negative electrode preparation process to 1 hour, the rest is the same as in Example 4.

[0209] Example 17

[0210] Except for changing the standing time in step (3) of the positive and negative electrode preparation process to 4 hours, the rest is the same as in Example 4.

[0211] Example 18

[0212] Except for changing the standing time in step (3) of the positive and negative electrode preparation process to 7 hours, the rest is the same as in Example 1.

[0213] Example 19

[0214] Except for changing the standing time in step (3) of the positive and negative electrode preparation process to 4 hours, the rest is the same as in Example 1.

[0215] Example 20

[0216] Except for changing the standing time in step (3) of the positive and negative electrode preparation process to 8 hours, the rest is the same as in Example 1.

[0217] Example 21

[0218] Except for changing the standing time in step (3) of the positive and negative electrode preparation process to 0.56 hours, the rest is the same as in Example 3.

[0219] Example 22

[0220] Except for changing the standing time in step (3) of the positive and negative electrode preparation process to 0.5 hours, the rest is the same as in Example 3.

[0221] Example 23

[0222] Except for changing the standing time in step (3) of the positive and negative electrode preparation process to 3 hours, the rest is the same as in Example 3.

[0223] Example 24

[0224] Except for changing the rolling time in step (3) of the positive and negative electrode preparation process to 135 seconds, the rest is the same as in Example 10.

[0225] Example 25

[0226] Except for changing the rolling time in step (3) of the positive and negative electrode preparation process to 115 seconds, the rest is the same as in Example 10.

[0227] Example 26

[0228] Except for changing the rolling time in step (3) of the positive and negative electrode preparation process to 15 seconds, the rest is the same as in Example 10.

[0229] Example 27

[0230] Except for changing the rolling time in step (3) of the positive and negative electrode preparation process to 10 seconds, the rest is the same as in Example 10.

[0231] Example 28

[0232] Except for changing the rolling time in step (3) of the positive and negative electrode preparation process to 150 seconds, the rest is the same as in Example 10.

[0233] Example 29

[0234] Except for changing the rolling time in step (3) of the positive and negative electrode preparation process to 360 seconds, the rest is the same as in Example 5.

[0235] Example 30

[0236] Except for changing the rolling time in step (3) of the positive and negative electrode preparation process to 340 seconds, the rest is the same as in Example 5.

[0237] Example 31

[0238] Except for changing the rolling time in step (3) of the positive and negative electrode preparation process to 45 seconds, the rest is the same as in Example 5.

[0239] Example 32

[0240] Except for changing the rolling time in step (3) of the positive and negative electrode preparation process to 9 seconds, the rest is the same as in Example 8.

[0241] Example 33

[0242] Except for replacing linear low-density polyethylene with the corresponding parts by weight of chlorinated polypropylene (PP-C, Yangzi Petrochemical-BASF Co., Ltd., R370Y, melting point 128℃, density 1.3 g / cm³), 3 Except for the glass transition temperature of -10°C and the melt flow index of 9 g / 10min, it is the same as in Example 10.

[0243] Example 34

[0244] Except for replacing linear low-density polyethylene with a corresponding part by weight of high-density polyethylene (HDPE, Yangzi Petrochemical-BASF Co., Ltd., 5000S, melting point 131℃, density 1.3 g / cm³), 3 Except for the glass transition temperature of -125°C and the melt flow index of 22 g / 10min, it is the same as in Example 10.

[0245] Example 35

[0246] Except for replacing linear low-density polyethylene with a corresponding weight part of low-density polyethylene (LDPE, Iran Petrochemical 2420D, melting point 125℃, density 1.3 g / cm³), 3 Except for the glass transition temperature of -100°C and the melt flow index of 20 g / 10min, it is the same as in Example 10.

[0247] Example 36

[0248] Preparation of positive electrode

[0249] (1) NCM523 (Kelode, MA-EN-CA-0020), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918g / cm³) were added. 3 (Glass transition temperature -120℃, melt index 12 g / 10min) are mixed evenly at a mass ratio of 93:3:4.

[0250] (2) Roll the mixture obtained in (1) (the rolling method is hot rolling, the temperature of the upper roller is 100℃, the temperature of the lower roller is 100℃, and the rolling time is 60 seconds) to obtain a pre-formed self-supporting electrode film.

[0251] (3) The preformed self-supporting electrode film obtained in (2) is hot-pressed at 5 MPa and 110°C for 10 minutes.

[0252] (4) The self-supporting electrode film obtained in (3) is combined with aluminum foil by means of rolling (the temperature of the upper roller is 80°C, the temperature of the lower roller (current collector side, the same below) is 150°C, and the rolling time is 30 seconds) through the lower surface of the hot pressing process in step (3) to obtain the positive electrode.

[0253] Preparation of negative electrode

[0254] (1) Gr (graphite), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130℃, density 0.918 g / cm³) were added. 3 Mix them evenly at a mass ratio of 95:2.5:2.5 (glass transition temperature -120℃, melt index 12 g / 10min).

[0255] (2) Roll the mixture obtained in (1) (the rolling method is hot rolling, the temperature of the upper roller is 100℃, the temperature of the lower roller is 100℃, and the rolling time is 60 seconds) to obtain a pre-formed self-supporting electrode film.

[0256] (3) The preformed self-supporting electrode film obtained in (2) is hot-pressed at 5 MPa and 110°C for 10 minutes.

[0257] (4) The self-supporting electrode film obtained in (3) is combined with the copper foil through the hot pressing process in step (3) by rolling with rollers (where the temperature of the upper roller is 80°C, the temperature of the lower roller is 150°C, and the rolling time is 30 seconds) to obtain the negative electrode.

[0258] Example 37

[0259] Except for changing the hot pressing temperature in step (3) of the positive and negative electrode preparation process to 120°C, the rest is the same as in Example 36.

[0260] Example 38

[0261] Except for changing the hot pressing temperature to 160°C and the hot pressing time to 3 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0262] Example 39

[0263] Except for changing the hot pressing temperature to 170°C and the hot pressing time to 3 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0264] Example 40

[0265] Except for changing the hot pressing temperature to 100°C and the hot pressing time to 12.44 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0266] Example 41

[0267] Except for changing the hot pressing temperature to 100°C and the hot pressing time to 13.74 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0268] Example 42

[0269] Except for changing the hot pressing temperature to 120°C and the hot pressing time to 9.37 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0270] Example 43

[0271] Except for changing the hot pressing temperature to 120°C and the hot pressing time to 10.49 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0272] Example 44

[0273] Except for changing the hot pressing temperature to 160°C and the hot pressing time to 3.22 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0274] Example 45

[0275] Except for changing the hot pressing temperature to 160°C and the hot pressing time to 3.98 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0276] Example 46

[0277] Except for changing the hot pressing temperature to 180°C and the hot pressing time to 0.73 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0278] Example 47

[0279] Except for changing the hot pressing temperature to 180°C and the hot pressing time to 0.15 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0280] Example 48

[0281] Except for changing the pressure in step (3) of the positive and negative electrode preparation process from 5 MPa to 20 MPa, the rest is the same as in Example 40.

[0282] Example 49

[0283] Except for changing the pressure in step (3) of the positive and negative electrode preparation process from 5 MPa to 20 MPa, the rest is the same as in Example 42.

[0284] Example 50

[0285] Except for changing the pressure in step (3) of the positive and negative electrode preparation process from 5 MPa to 20 MPa, the rest is the same as in Example 46.

[0286] Example 51

[0287] Except for changing the pressure in step (3) of the positive and negative electrode preparation process from 5 MPa to 20 MPa, the rest is the same as in Example 45.

[0288] Example 52

[0289] Except for changing the hot pressing temperature in step (3) of the positive and negative electrode preparation process to 100°C, the rest is the same as in Example 36.

[0290] Example 53

[0291] Except for changing the hot pressing temperature to 120°C and the hot pressing time to 8 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0292] Example 54

[0293] Except for changing the hot pressing temperature to 160°C and the hot pressing time to 4.5 minutes in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0294] Example 55

[0295] Except for changing the hot pressing temperature to 180°C and the hot pressing time to 1 minute in step (3) of the positive and negative electrode preparation process, the rest is the same as in Example 36.

[0296] Comparative Example 1

[0297] Except for step (3) not being performed during the preparation of the positive and negative electrodes, the process is the same as in Example 1.

[0298] Comparative Example 2

[0299] Except for changing the settling temperature in step (3) of the positive and negative electrode preparation process to 90°C, the rest is the same as in Example 1.

[0300] Comparative Example 3

[0301] Except for changing the settling temperature in step (3) of the positive and negative electrode preparation process to 190°C, the rest is the same as in Example 3.

[0302] Comparative Example 4

[0303] Except for changing the heat treatment temperature in step (3) of the positive and negative electrode preparation process to 90°C, the rest is the same as in Example 5.

[0304] Comparative Example 5

[0305] Except for changing the heat treatment temperature in step (3) of the positive and negative electrode preparation process to 190°C, the rest is the same as in Example 8.

[0306] Comparative Example 6

[0307] Except for changing the hot pressing temperature in step (3) of the positive and negative electrode preparation process to 90°C, the rest is the same as in Example 41.

[0308] Comparative Example 7

[0309] Except for changing the hot pressing temperature in step (3) of the positive and negative electrode preparation process to 184°C, the rest is the same as in Example 47.

[0310] Measurement Examples

[0311] 1. Electrochemical performance measurement methods

[0312] Assembly of all batteries

[0313] The positive and negative electrodes prepared using the examples and comparative examples, as well as the porous membrane Celgard 2500 (polypropylene / polyethylene / polypropylene composite porous membrane, manufactured by Dongguan Kelude Experimental Equipment Technology Co., Ltd.) and electrolyte ( A solution in a DEC:EC mixture with a volume ratio of 1:1 (the solution also contains 10% FEC and 1% VC based on the total volume of the solution). A 1M electrolyte concentration was used to assemble a full cell (the ratio of the theoretical capacity of the negative electrode to the theoretical capacity of the positive electrode, N / P, was 1.1). The positive electrode pad, positive electrode sheet, separator, negative electrode sheet, and negative electrode spring were arranged from bottom to top inside the positive electrode shell. Electrolyte was injected, the negative electrode shell was then snapped in, and the cells were pressed together to obtain a coin cell. The positive electrode shell, negative electrode shell, pad, and spring used were all made of stainless steel and purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd.

[0314] First-time coulombic efficiency and discharge specific capacity

[0315] The assembled full cells were first activated at 30°C. The assembled full cells were charged to 2.7V at a 0.1C rate, then allowed to stand for 10 minutes, followed by discharge to 4.2V at a 0.1C rate, and then allowed to stand for 10 minutes. This constituted one charge-discharge cycle; this cycle was repeated 5 times to complete the activation process. Then, starting from the 6th cycle, the charge-discharge rate was adjusted to 0.2C / 0.5C.

[0316] Record the charging and discharging capacity of the first cycle (activation). Divide the discharging capacity by the charging capacity and then multiply by 100% to obtain the initial coulombic efficiency.

[0317] The activated full cell was subjected to charge-discharge cycles of n-5 times under the same conditions as in cycle 6, yielding the discharge and charge capacity for cycle n. The discharge capacity for each cycle was divided by the mass of the positive electrode active material in the battery to obtain the discharge specific capacity (the data in Table 2 are the discharge specific capacities for cycles 1 and 50).

[0318] 2. Other property measurement methods

[0319] Tensile strength

[0320] The tensile strength of a single self-supporting membrane in the length direction was measured using a small-tonnage mechanical tensile testing machine (brand: SHIMADZU, model: EZ-LX HS).

[0321] Table 1

[0322]

[0323] Table 2

[0324]

[0325] 1 The tensile strength of the positive and negative self-supporting electrode films along their length is shown before and after the " / ".

[0326] As can be seen from Tables 1 and 2, compared with Comparative Examples 1-7, the self-supporting electrode films of Examples 1-55 of the present invention have higher tensile strength in the length direction, and all are greater than 0.15 MPa; at the same time, the initial coulombic efficiency, initial discharge capacity and cycle performance (discharge capacity after 50 cycles) of Examples 1-55 are better than those of Comparative Examples 1-7 under the same conditions.

[0327] Specifically, comparing Examples 1, 5, and 36 with Comparative Example 1, it can be seen that, compared to Comparative Example 1 without heat treatment (tensile strength of 0.12 / 0.13 MPa), the self-supporting electrode films obtained in Examples 1, 5, and 36 have greater tensile strengths in the length direction (0.26 / 0.27 MPa, 0.28 / 0.30 MPa, and 0.32 / 0.34 MPa, respectively), and also have higher initial coulombic efficiency, initial discharge specific capacity, and discharge specific capacity after 50 cycles (described in the same order below, without further repetition) (the above performance parameters for Example 1 are 80.4%, 132.1 mAh / g, and 113.6 mAh / g, respectively; for Example 5, they are 82%, 132.5 mAh / g, and 102.4 mAh / g, respectively; and for Example 36, they are 76.4%, 120.1 mAh / g, and 113.6 mAh / g, respectively). The results (108.2 mAh / g and 108.2 mAh / g) are both superior to those of Comparative Example 1 (the above performance parameters of Comparative Example 1 are 62.8%, 97 mAh / g and 70 mAh / g, respectively). This indicates that performing separate heat treatment (such as standing, rolling or hot pressing, etc.) other than the preforming and compounding processes is beneficial to improving the tensile strength of the obtained self-supporting electrode film in the length direction, as well as improving the initial coulombic efficiency, initial discharge specific capacity and cycle performance of the obtained electrode.

[0328] Comparing Examples 1 and 3 with Comparative Examples 2-3, it can be seen that the only difference between Example 1 and Comparative Example 2 is that the static temperature during heat treatment in Example 1 is 100°C, while the static temperature during heat treatment in Comparative Example 2 is 90°C. Example 1 also shows differences in tensile strength (0.26 / 0.27 MPa) and electrochemical performance (80.4%, 132.1 MPa) in the length direction. The tensile strength (0.25 / 0.27 MPa) and electrochemical performance (79.4%, 127.2 mAh / g, and 99.9 mAh / g) of Example 3 were significantly better than those of Comparative Example 2 (tensile strength in the length direction was 0.13 / 0.15 MPa, and electrochemical performance test results were 67.2%, 112 mAh / g, and 72.3 mAh / g, respectively). The only difference between Example 3 and Comparative Example 3 was that the static temperature during heat treatment in Example 3 was 180°C, while the static temperature during heat treatment in Comparative Example 3 was 190°C. The tensile strength (0.25 / 0.27 MPa) and electrochemical performance (79.4%, 127.2 mAh / g, and 99.9 mAh / g) of Example 3 were significantly better than those of Comparative Example 3 (tensile strength in the length direction was 0.13 / 0.19 MPa, and electrochemical performance test results were 70%, 110 mAh / g, and 70 mAh / g, respectively). Similar patterns can be found when comparing Example 5 and Example 8 with Comparative Examples 4 and 5, and when comparing Example 41 and Example 47 with Comparative Examples 6-7. This indicates that, compared to the heat treatment temperature T in °C v The melting point T of the adhesive (in °C) m Not satisfied In the case of heat treatment temperature T (in °C) v The melting point T of the adhesive (in °C) m When this correlation is satisfied, the self-supporting electrode film of the resulting electrode has greater tensile strength in the length direction, and better initial coulombic efficiency, initial discharge capacity, and cycle performance (discharge capacity after 50 cycles).

[0329] Comparing Examples 1 and 18-20, it can be seen that the settling time in Example 1 was 5 hours, while the settling time in Example 19 was 4 hours. The tensile strength (0.26 / 0.27 Pa) of the self-supporting electrode film in the length direction of the electrode obtained in Example 1 is greater than that of the self-supporting electrode film in the length direction of the electrode obtained in Example 19 (0.18 / 0.18 MPa). Furthermore, the electrochemical performance of Example 1 (80.4%, 132.1%) is also superior. The tensile strength of the self-supporting electrode film of the electrode obtained in Example 18 (71.2%, 101.2 mAh / g and 113.6 mAh / g) was better than that of Example 19 (71.2%, 101.2 mAh / g and 84.9 mAh / g); the standing time of Example 18 was 7 hours, while that of Example 20 was 8 hours. The tensile strength of the self-supporting electrode film of the electrode obtained in Example 18 in the longitudinal direction (0.27 / 0.30 MPa) was greater than that of the self-supporting electrode film of the electrode obtained in Example 20 (0.18 / 0.19 MPa) in the longitudinal direction. Moreover, the electrochemical performance of Example 18 (81.4%, 132.9 mAh / g and 114.8 mAh / g) was better than that of Example 20 (72.5%, 101.8 mAh / g and 85.5 mAh / g). Similar patterns can be observed in other embodiments that also involve heat treatment by a static method, such as Embodiments 4 and 14-17, or Embodiments 3 and 21-23; in embodiments involving heat treatment by a rolling method, such as Embodiments 5 and 29-31, or Embodiments 10 and 24-28; and in embodiments involving heat treatment by a hot pressing method, such as Embodiments 37, 42-43, and 53, or Embodiments 38, 44-45, and 54, or Embodiments 46-47 and 55. This indicates that when performing individual heat treatments, a specific correlation is found between the heat treatment temperature and the heat treatment time (e.g., for static heat treatment, the heat treatment temperature T in °C). v The resting time t1, measured in hours, satisfies: For heat treatment by roll forming, the heat treatment temperature T is expressed in °C. v The rolling time t2, measured in seconds, satisfies: For heat treatment via hot pressing, the heat treatment temperature T is expressed in °C. v The hot pressing time t3, measured in minutes, satisfies: Compared to cases where the above correlation is not met, the self-supporting electrode film of the obtained electrode has greater tensile strength in the length direction, and better initial coulombic efficiency, initial discharge capacity, and cycle performance (discharge capacity after 50 cycles).

[0330] Furthermore, comparing Examples 1-4, or Examples 5-10, or Examples 36-39, or Examples 10 and Examples 24-28, it can also be seen that by further optimizing the heat treatment temperature T...v The melting point T of the adhesive m The relationship (e.g.) ), or heat treatment temperature T v The relationship with the rolling time t2 (e.g.) Furthermore, it can further improve the tensile strength of the self-supporting electrode film in the length direction, as well as the subcoulombic efficiency, initial discharge capacity, and cycle performance.

[0331] Furthermore, it can be seen from Examples 11-13 and Examples 33-35 that the above principles also apply to cases where different adhesives or mixtures of multiple adhesives are used.

[0332] The above description is merely an exemplary embodiment of the present invention. It should be noted that those skilled in the art can make improvements to the present invention without departing from the inventive concept, and all such improvements fall within the scope of protection of the present invention.

Claims

1. An electrode comprising a current collector and a self-supporting electrode film, wherein the self-supporting electrode film comprises an electrode active material, a conductive agent, and a binder, the binder comprises at least 30% by weight of polyethylene and / or polypropylene based on the total dry weight of the binder, and the self-supporting electrode film has a tensile strength in the length direction of 0.15 MPa or more. wherein at least a portion of the polyethylene and / or polypropylene forms fibers, and the formed fibers are oriented fibers oriented in a thickness direction of the self-supporting electrode film 45° or less, wherein "oriented fibers" means that the overall orientation of the fibers formed from the polyethylene and / or polypropylene is oriented in a thickness direction of the self-supporting electrode film fibers oriented within 45° or less.

2. The electrode according to claim 1, wherein the binder comprises at least 50% by weight of polyethylene and / or polypropylene based on the total dry weight of the binder.

3. The electrode according to claim 1, wherein the binder comprises at least 60% by weight of polyethylene and / or polypropylene based on the total dry weight of the binder.

4. The electrode according to claim 1, wherein the binder comprises 80-100% by weight of polyethylene and / or polypropylene based on the total dry weight of the binder.

5. The electrode according to claim 1, wherein the self-supporting electrode film has a tensile strength in the length direction of 0.20 MPa or more.

6. The electrode according to claim 1, wherein the self-supporting electrode film has a tensile strength in the length direction of 0.25 MPa or more.

7. The electrode according to claim 1, wherein the self-supporting electrode film has a tensile strength in the length direction of 0.30 MPa or more.

8. The electrode according to any one of claims 1-7, wherein the binder comprises no more than 50% by weight of polytetrafluoroethylene based on the total dry weight of the binder.

9. The electrode according to claim 8, wherein the binder does not contain polytetrafluoroethylene.

10. The electrode according to any one of claims 1-7, wherein the binder consists of polyethylene and / or polypropylene.

11. The electrode according to claim 1, wherein the formed fibers are in the thickness direction of the self-supporting electrode film. Oriented fibers with an orientation of less than 30°.

12. The electrode according to claim 1, wherein the formed fibers are oriented fibers oriented within 15° of the thickness direction of the self-supporting electrode film. 15° of the thickness direction of the self-supporting electrode film.

13. The electrode according to any one of claims 1-7, wherein one or more of the following conditions are satisfied: (1) the total weight of the binder is 1-10% by weight of the total dry weight of the self-supporting electrode film; (2) the polyethylene is selected from one or more of ultra-high molecular weight polyethylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, and linear low-density polyethylene; (3) the polyethylene has a melting point ranging from 85-150°C; (4) the polyethylene has a glass transition temperature ranging from -120°C to -70°C; (5) the polyethylene has a melt index ranging from 0.1-100 g / 10 min measured according to ISO 1133-1:2022 at a temperature of 190°C under a load of 2.16 kg; (6) the polypropylene is selected from one or more of polypropylene homopolymer, polypropylene copolymer; (7) the polypropylene has a melting point ranging from 105-180°C; (8) the polypropylene has a glass transition temperature ranging from -20°C to 10°C; (9) the polypropylene has a melt index ranging from 0.3-100 g / 10 min measured according to ISO 1133-1:2022 at a temperature of 230°C under a load of 2.16 kg; and (10) the polypropylene is selected from one or more of polypropylene homopolymer, polypropylene copolymer. (10) one or more of polytetrafluoroethylene, polyacrylic acid, sodium carboxymethylcellulose, polyvinylidene fluoride and its derivatives, polyvinyl butyral, styrene butadiene rubber, polyvinyl alcohol, sodium alginate, polyimide, polylactic acid, polyisobutylene, polystyrene, polycaprolactone, polycarbonate, polyamide, poly-L-lactic acid, polyolefin copolymer, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene adipamide, ethylene acrylic acid copolymer, polyvinyl acetate, polyurethane, epoxy resin, chitosan, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene propylene copolymer, polylactic acid-glycolic acid copolymer, epoxy acrylate, ethylene-vinyl acetate copolymer, polyformaldehyde, polyphenylene sulfide, paraffin wax, gelatin, beeswax, in addition to polyethylene / polypropylene, wherein the melting point of polyethylene and polypropylene is measured using a differential scanning calorimeter according to the following conditions: nitrogen atmosphere, temperature rising rate of 10°C / min, test temperature range of room temperature to 200°C, recording the solid-liquid phase transition temperature during the test, and taking the lowest solid-liquid phase transition temperature as the melting point of the binder, wherein the glass transition temperature of polyethylene and polypropylene is measured as follows: according to ASTM D3418-2015 by differential scanning calorimetry with a temperature rising rate of 10°C / min from -120°C to 25°C, constant temperature for 1 h, then a temperature decreasing rate of 10°C / min from 25°C to -120°C, and a second temperature rising from -120°C to 25°C with a temperature rising rate of 10°C / min, constant temperature for 1 h, and then a temperature decreasing rate of 10°C / min from 25°C to -120°C.

14. The electrode of claim 13, wherein the total weight of the binder is 1-5 wt% of the total dry weight of the self-supporting electrode film.

15. The electrode of claim 13, wherein the polyethylene is selected from polyethylene homopolymer or polyethylene copolymer.

16. The electrode of claim 13, wherein the melting point of the polyethylene ranges from 110-140°C.

17. The electrode of claim 13, wherein the glass transition temperature of the polyethylene ranges from -120°C to -90°C.

18. The electrode of claim 13, wherein the polyethylene has a melt index ranging from 10-30 g / 10 min measured according to ISO 1133-1:2022 at a temperature of 190°C and a load of 2.16 kg.

19. The electrode of claim 1, wherein the polypropylene is selected from chlorinated polypropylene.

20. The electrode of claim 13, wherein the melting point of the polypropylene ranges from 120-150°C.

21. The electrode of claim 13, wherein the polypropylene has a melt index ranging from 1-20 g / 10 min measured according to ISO 1133-1:2022 at a temperature of 230°C and a load of 2.16 kg.

22. An energy storage device comprising the electrode of any one of claims 1-21.

23. The energy storage device according to claim 22, wherein any one of the following conditions is satisfied: (11) the energy storage device is a lithium-ion secondary battery; or (12) the energy storage device is a sodium-ion secondary battery; or (13) the energy storage device is a supercapacitor.

24. The energy storage device according to claim 23, wherein the positive electrode active material of the lithium-ion secondary battery is selected from one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-containing phosphate of olivine structure.

25. The energy storage device of claim 23, wherein the positive active material of the lithium-ion secondary battery is selected from one or more of , , , , , , and .

26. The energy storage device according to claim 23, wherein the negative electrode active material of the lithium-ion secondary battery is selected from one or more of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon-based material, tin-based material, lithium titanate, and metallic lithium.

27. The energy storage device according to claim 23, wherein the negative electrode active material of the lithium-ion secondary battery is selected from one or more of graphite and silicon-based material.

28. The energy storage device according to claim 23, wherein the negative electrode active material of the lithium-ion secondary battery is selected from one or more of graphite, silicon-carbon composite, and silicon alloy.

29. The energy storage device according to claim 23, wherein the positive electrode active material of the sodium-ion secondary battery is selected from one or more of layered transition metal oxide or Prussian blue analogues.

30. The energy storage device of claim 23, wherein the sodium-ion secondary battery has a cathode active material selected from one or more of , , , , and .

31. The energy storage device according to claim 23, wherein the negative electrode active material of the sodium-ion secondary battery is selected from one or more of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon-based material, and tin-based material.

32. The energy storage device according to claim 23, wherein the negative electrode active material of the sodium-ion secondary battery is selected from one or more of graphite and silicon-based material.

33. The energy storage device according to claim 23, wherein the negative electrode active material of the sodium-ion secondary battery is selected from one or more of graphite, silicon-carbon composite, and silicon alloy.

34. The energy storage device according to claim 23, wherein the positive electrode active material of the supercapacitor is selected from one or more of metal oxide, conductive polymer, and carbon material.

35. The energy storage device of claim 23, wherein the positive electrode active material of the supercapacitor is selected from one or more of , NiO, , polyaniline, polypyrrole, activated carbon, graphene, and biochar.

36. The energy storage device according to claim 23, wherein the negative electrode active material of the supercapacitor is selected from one or more of metal, carbon material, conductive polymer, metal oxide, metal organic framework (MOF) derived material.

37. The energy storage device of claim 23, wherein the negative active material of the supercapacitor is selected from one or more of aluminum, zinc, activated carbon, graphite, polyaniline, polypyrrole, polythiophene, and graphene.

38. A method for preparing an electrode according to claim 1, the method comprising: Step (i): providing an electrode active material, a conductive agent, and a binder, wherein the binder comprises at least 30 wt% of polyethylene and / or polypropylene based on the total dry weight of the binder; Step (ii): mixing the electrode active material, the conductive agent, and the binder; and Step (iii): obtaining an electrode from the mixture obtained in step (ii), wherein step (iii) comprises: Step (iii-1): pre-forming the mixture obtained in step (ii) to obtain a pre-formed self-supporting electrode film; and and ​ Step (iii-2): providing a current collector and compounding the current collector with the preformed self-supporting electrode film obtained from the previous step, and step (iii) comprises a heat treatment process, wherein the heat treatment temperature T of the heat treatment process is in °C v with the melting point T of the binder in °C m satisfies: wherein the melting point is measured using a differential scanning calorimeter according to the following conditions: nitrogen atmosphere, heating rate 10 °C / min, test temperature range from room temperature to 200 °C, recording the solid-liquid phase transition temperature during the test, taking the lowest solid-liquid phase transition temperature as the melting point of the binder, wherein the heat treatment process is performed during step (iii-1), or during step (iii-2), or independently from step (iii-1) and step (iii-2); wherein the self-supporting electrode film in the electrode prepared by the electrode preparation method has a tensile strength in the length direction of 0.15 MPa or more.

39. The electrode preparation method according to claim 38, wherein the binder comprises at least 50 wt% of polyethylene and / or polypropylene based on the total dry weight of the binder.

40. The electrode preparation method according to claim 38, wherein the binder comprises at least 60 wt% of polyethylene and / or polypropylene based on the total dry weight of the binder.

41. The electrode preparation method according to claim 38, wherein the binder comprises 80-100 wt% of polyethylene and / or polypropylene based on the total dry weight of the binder.

42. The electrode production method according to claim 38, wherein the heat treatment temperature T of the heat treatment process in °C v the melting point T of the binder in °C m satisfies: .

43. The electrode preparation method according to claim 38, wherein the heat treatment process is performed between step (iii-1) and step (iii-2).

44. The electrode preparation method according to any one of claims 38-43, wherein the heat treatment process is performed by standing, rolling or hot pressing.

45. The electrode production method according to any one of claims 38-43, wherein the heat treatment process is performed by standing, and the heat treatment temperature T in °C v the standing time tl in hours satisfies: .

46. The electrode production method according to any one of claims 38-43, wherein the heat treatment process is performed by rolling, and the heat treatment temperature T in °C v satisfies: .

47. The electrode production method according to claim 46, wherein the heat treatment temperature T in °C v The roll pressing time t2 in seconds satisfies: .

48. The electrode preparation method according to claim 46, wherein the rolling is a pair-rolling.

49. The electrode preparation method according to claim 48, wherein in the pair-rolling, the temperature of the upper roller is equal to the temperature of the lower roller.

50. The electrode production method according to any one of claims 38-43, wherein the heat treatment process is performed by hot pressing, and a heat treatment temperature T in °C v satisfies: .

51. The electrode preparation method according to claim 50, wherein the pressure of the hot pressing is 5-20 MPa.

52. The electrode preparation method according to any one of claims 38-43, wherein one or more of the following conditions are met: (a) the total weight of the binder accounts for 1-10 wt% of the total dry weight of the self-supporting electrode film; (b) the polyethylene is selected from one or more of ultra-high molecular weight polyethylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene and linear low-density polyethylene; (c) the melting point of the polyethylene ranges from 85-150 °C; (d) the glass transition temperature of the polyethylene is from -120 °C to -70 °C; (e) the melt index of the polyethylene measured according to ISO 1133-1:2022 at a temperature of 190 °C under a load of 2.16 kg ranges from 0.1-100 g / 10 min; (f) the polypropylene is selected from one or more of polypropylene homopolymer and polypropylene copolymer; (g) the melting point of the polypropylene ranges from 105-180 °C; (h) the glass transition temperature of the polypropylene is from -20 °C to 10 °C; (i) the melt index of the polypropylene measured according to ISO 1133-1:2022 at a temperature of 230 °C under a load of 2.16 kg ranges from 0.3-100 g / 10 min; (j) the binder further comprises, in addition to polyethylene / polypropylene, one or more of polytetrafluoroethylene, polyacrylic acid, sodium carboxymethylcellulose, polyvinylidene fluoride and its derivatives, polyvinyl butyral, styrene butadiene rubber, polyvinyl alcohol, sodium alginate, polyimide, polylactic acid, polyisobutylene, polystyrene, polycaprolactone, polycarbonate, polyamide, poly-L-lactic acid, polyolefin copolymer, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene adipamide, ethylene acrylic acid copolymer, polyvinyl acetate, polyurethane, epoxy resin, chitosan, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene propylene copolymer, polylactic acid-glycolic acid copolymer, epoxy acrylate, ethylene-vinyl acetate copolymer, polyformaldehyde, polyphenylene sulfide, paraffin wax, gelatin, beeswax; (k) the electrode is an electrode of an energy storage device and the energy storage device is a lithium ion secondary battery; or (l) the electrode is an electrode of an energy storage device and the energy storage device is a sodium ion secondary battery; or (m) the electrode is an electrode of an energy storage device and the energy storage device is a supercapacitor; wherein the glass transition temperature of polyethylene and polypropylene is measured as follows: according to ASTM D3418-2015 by differential scanning calorimetry with a temperature ramp of 10 °C / min from -120 °C to 25 °C, 1 h isothermal, then a temperature ramp of 10 °C / min from 25 °C to -120 °C, and a second temperature ramp of 10 °C / min from -120 °C to 25 °C, 1 h isothermal, then a temperature ramp of 10 °C / min from 25 °C to -120 °C.

53. The method of manufacturing according to claim 52, wherein the total weight of the binder is 1-5 wt% of the total dry weight of the self-supporting electrode film.

54. The method of manufacturing according to claim 52, wherein the polyethylene is selected from polyethylene homopolymer or polyethylene copolymer.

55. The method of manufacturing according to claim 52, wherein the melting point of the polyethylene ranges from 110-140 °C.

56. The method of manufacturing according to claim 52, wherein in condition (d), the glass transition temperature of the polyethylene ranges from -120 °C to -90 °C.

57. The method of manufacturing according to claim 52, wherein in condition (e), the polyethylene has a melt index ranging from 10-30 g / 10 min measured according to ISO 1133-1:2022 at a temperature of 190 °C under a load of 2.16 kg.

58. The method of manufacturing according to claim 38, wherein the polypropylene is selected from chlorinated polypropylene.

59. The method of manufacturing according to claim 52, wherein the melting point of the polypropylene ranges from 120-150 °C.

60. The method of manufacturing according to claim 52, wherein in condition (i), the polypropylene has a melt index ranging from 1-20 g / 10 min measured according to ISO 1133-1:2022 at a temperature of 230 °C under a load of 2.16 kg.

61. The method of manufacturing of claim 52, wherein the positive active material of the lithium-ion secondary battery 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 olivine-structured lithium-containing phosphates.

62. The production method according to claim 52, wherein in the condition (k), the positive electrode active material of the lithium-ion secondary battery is selected from one or more of , , , , , , and .

63. The method of manufacturing of claim 52, wherein the negative active material of the lithium-ion secondary battery is selected from one or more of natural graphite, artificial graphite, meso-carbon microbe (MCMB), hard carbon, soft carbon, silicon-based materials, tin-based materials, lithium titanate, and metallic lithium.

64. The method of manufacturing of claim 52, wherein the negative active material of the lithium-ion secondary battery is selected from one or more of graphite and silicon-based materials.

65. The method of manufacturing of claim 52, wherein the negative active material of the lithium-ion secondary battery is selected from one or more of graphite, silicon-carbon composites, and silicon alloys.

66. The method of manufacturing of claim 52, wherein the positive active material of the sodium-ion secondary battery is selected from one or more of layered transition metal oxides or Prussian blue analogues.

67. The production method of claim 52, wherein the sodium-ion secondary battery positive electrode active material is selected from one or more of , , , , and .

68. The method of manufacturing of claim 52, wherein the negative active material of the sodium-ion secondary battery is selected from one or more of natural graphite, artificial graphite, meso-carbon microbe (MCMB), hard carbon, soft carbon, silicon-based materials, and tin-based materials.

69. The method of manufacturing of claim 52, wherein the negative active material of the sodium-ion secondary battery is selected from one or more of graphite and silicon-based materials.

70. The method of manufacturing of claim 52, wherein the negative active material of the sodium-ion secondary battery is selected from one or more of graphite, silicon-carbon composites, and silicon alloys.

71. The method of manufacturing of claim 52, wherein the positive active material of the supercapacitor is selected from one or more of metal oxides, conductive polymers, and carbon materials.

72. The method of manufacturing of claim 52, wherein the positive electrode active material of the supercapacitor is selected from one or more of , NiO, , polyaniline, polypyrrole, activated carbon, graphene, and biochar.

73. The method of manufacturing of claim 52, wherein the negative active material of the supercapacitor is selected from one or more of metals, carbon materials, conductive polymers, metal oxides, metal-organic framework (MOF) derived materials.

74. The method of manufacturing of claim 52, wherein the negative active material of the supercapacitor is selected from one or more of aluminum, zinc, activated carbon, graphite, polyaniline, polypyrrole, polythiophene, and MnO2.

75. An electrode made by the method of manufacturing of any one of claims 38-74.

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