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

Abstract

The present invention 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 comprising 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 above. The invention also relates to an energy storage device comprising the electrode, an electrode production system and a preparation method of the electrode. The electrode disclosed by the invention or the electrode prepared by the electrode preparation method disclosed by the invention has excellent first coulombic efficiency, relatively high specific capacity and excellent cycle performance.

Description

TECHNICAL FIELD

[0001] The present application relates generally to the field of electrochemical energy storage technology. In particular, the present application relates to an electrode and an energy storage device comprising the same, and an electrode production system and a method for preparing the electrode. BACKGROUND

[0002] Polyethylene and / or polypropylene have very wide applications in the fields of packaging, construction, household products, etc. In recent years, with the vigorous development of new energy technology, energy storage devices such as secondary batteries have attracted widespread attention. In energy storage devices such as secondary batteries, polyethylene and / or polypropylene are generally used to manufacture separators, wherein polyethylene separators have good flexibility and elasticity, and polypropylene separators have high stiffness, wear resistance and impact resistance. However, in the prior art, polyethylene and / or polypropylene are rarely used as binders to bind electrode active materials, conductive agents, etc. to manufacture electrodes in specific examples. One of the reasons is that when polyethylene and / or polypropylene are used as binders, the electrodes prepared are difficult to meet the growing demand for electrochemical performance such as initial coulombic efficiency, discharge specific capacity and cycle performance.

[0003] Therefore, it is of great significance to develop a new electrode prepared by using polyethylene and / or polypropylene as a binder, which has excellent initial coulombic efficiency, high discharge specific capacity and excellent cycle performance, to meet market demand. SUMMARY

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

[0005] In a first aspect, 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 wt%, preferably at least 50 wt%, more preferably at least 60 wt%, further preferably at least 80 wt%, for example 80-100 wt% 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, 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 in the length direction of 0.15 MPa or more, the electrode is easy to obtain excellent initial coulombic efficiency, high discharge specific capacity and excellent cycle performance.

[0007] In a second aspect, the present application relates to an energy storage device comprising the electrode according to the first aspect of the present application.

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

[0009] (a) a feed module for providing an electrode active material, a conductive agent, and a binder;

[0010] (b) a mixing module downstream of the (a) feed module for mixing the electrode active material, the conductive agent, and the binder;

[0011] (c) a pre-forming module downstream of the (b) mixing module for pre-forming the mixture obtained from the mixing module to obtain a pre-formed self-supporting electrode film;

[0012] (d) a current collector providing module for providing a current collector;

[0013] (e) a compounding module downstream of the (c) pre-forming module and the (d) current collector providing module for compounding the pre-formed self-supporting electrode film and the current collector;

[0014] (f) optionally a heat treatment module between the (c) pre-forming module and the (e) compounding module; and

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

[0016] In a fourth aspect, the present application relates to an electrode production method comprising:

[0017] Step (i) providing an electrode active material, a conductive agent, and a binder, wherein the binder comprises at least 30 wt.-%, preferably at least 50 wt.-%, more preferably at least 60 wt.-%, further preferably at least 80 wt.-%, such as 80-100 wt.-%, of polyethylene and / or polypropylene based on the total dry weight of the binder;

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

[0019] Step (iii) obtaining an electrode from the mixture obtained in step (ii),

[0020] wherein step (iii) comprises:

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

[0022] Step (iii-2) providing a current collector and compounding the current collector with the pre-formed self-supporting electrode film obtained in the previous step,

[0023] and step (iii) comprises a heat treatment process, wherein the heat treatment temperature T of the heat treatment process is in °C v and the melting point T of the binder is in °C m satisfies: , preferably ,

[0024] wherein the heat treatment process is carried out during step (iii-1), or during step (iii-2), or independently from step (iii-1) and step (iii-2), for example between step (iii-1) and step (iii-2).

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

[0026] The electrode production method of the present application is easy to operate, the self-supporting electrode film of the obtained electrode has a high tensile strength in the length direction, and the electrode has excellent first coulombic efficiency, a high discharge specific capacity, and excellent cycle performance. BRIEF DESCRIPTION OF DRAWINGS

[0027] To make the technical solutions of the present application clearer, the drawings required for describing the embodiments will be briefly described below. It should be understood that these drawings are only for the purpose of making it easier for the skilled person to understand the present application, and are not intended to limit the scope of the present application.

[0028] Figure 1 Schematic diagram of an electrode production system according to an embodiment of the present application. DETAILED DESCRIPTION

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

[0030] Unless otherwise specified, the meanings of the scientific and technical terms in the present specification are the same as those generally understood by those skilled in the art.

[0031] In the present application, unless otherwise specified, the temperature is room temperature (25°C), the atmosphere is air, and the pressure is atmospheric pressure.

[0032] It should be noted that, in the present text, for a single binder, for example linear low density polyethylene, the "melting point T of the binder" is the melting point of the linear low density polyethylene itself; for a mixture of multiple types of binders, for example a mixture of linear low density polyethylene and polypropylene copolymer, the "melting point T of the binder" is the melting point of the mixture of linear low density polyethylene and polypropylene copolymer. m m ​"melting point of the binder Tm" is the lower temperature of the solid-liquid phase transition exhibited by the mixture during the melting point determination. For example, if the binder mixture exhibits only one solid-liquid phase transition temperature during the melting point determination, this temperature is the "melting point of the binder Tm"; if the binder mixture exhibits several solid-liquid phase transition temperatures during the melting point determination, the lowest temperature of these temperatures is the "melting point of the binder Tm". In the present application, the melting point can be measured by methods conventionally used in the art, for example by differential scanning calorimetry (DSC) method. m m In the present application, the melting point can be measured by methods conventionally used in the art, for example by differential scanning calorimetry (DSC) method.

[0033] The term "high temperature" herein refers to a temperature higher than room temperature, for example a temperature in the range defined by any two of 50-200 °C, for example 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 °C, unless specified otherwise.

[0034] The present application relates to an electrode and an energy storage device including the same, and an electrode production system and a method of manufacturing the electrode.

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

[0036] Electrode

[0037] A first aspect of the present application provides an electrode including a current collector and a self-supporting electrode film, wherein the self-supporting electrode film includes an electrode active material, an electrically conductive agent, and a binder, the binder includes at least 30% by weight, preferably at least 50% by weight, more preferably at least 60% by weight, further 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 film has a tensile strength in the length 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 employs polyethylene and / or polypropylene as a binder, and the electrode film of the electrode has a tensile strength in the length direction of 0.15 MPa or more, the electrode easily achieves excellent initial coulombic efficiency, a high discharge specific capacity, and excellent cycle performance.

[0039] ​For example, the self-supporting electrode film can have a tensile strength in the length direction of, for example, 0.15-0.50 MPa or 0.25-0.50 MPa, for example, 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, 041, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50 MPa, or a range defined by any two of them. In the present application, the tensile strength can be measured by a method conventionally used in the art, for example, can be measured using a small tonnage mechanical tensile tester.

[0040] In the electrode of the present application, the binder includes polyethylene and / or polypropylene, and the total content of polyethylene and polypropylene (i.e., the content of polyethylene when polypropylene is not present, the content of polypropylene when polyethylene is not present, 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, further preferably at least 80% by weight, for example, 80-100% by weight; for example, can be 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100% by weight, or a range defined by any two of them.

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

[0042] In some embodiments, the binder includes polypropylene, for example, chlorinated polypropylene, and the content of polypropylene, for example, chlorinated polypropylene, can be 50-100%, preferably 80-100%, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100% by weight, or a range defined by any two of them.

[0043] In some embodiments, the binder includes polytetrafluoroethylene in an amount of no more than 50% by weight, based on the total dry weight of the binder.

[0044] Although adding polytetrafluoroethylene (PTFE) and the like to the binder helps to improve tensile strength, the decomposition of polytetrafluoroethylene during battery application can cause many problems. In this article, the content of polytetrafluoroethylene is no more than 50 weight%, for example, no more than 45 weight%, no more than 40 weight%, no more than 35 weight%, no more than 30 weight%, no more than 25 weight%, no more than 20 weight%, no more than 15 weight%, no more than 10 weight%, no more than 5 weight%, or no more than 2 weight%. In some embodiments, the binder used in the present invention does not contain polytetrafluoroethylene.

[0045] In some embodiments, the binder 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 "fiber formation" refers to the presence of a fiber-like 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 forms fibers and the formed fibers are arranged in the thickness direction of the self-supporting electrode film. Within 45°, e.g. Within 30°, e.g. The term "oriented fibers" refers to fibers formed from polyethylene and / or polypropylene that are oriented in the thickness direction of the self-supporting electrode film. Within 45°, e.g. Within 30°, e.g. Fibers oriented within 15°. This excludes fibers such as those formed from polyethylene and / or polypropylene where only a portion of the fibers meet the defined orientation but the fibers as a whole do not meet the defined orientation. Without wishing to be bound by any theory, it is believed that when at least a portion of the polyethylene and / or polypropylene forms fibers and the fibers formed 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 properties such as the first 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°, The overall orientation of the fibers formed of polyethylene and / or polypropylene can be observed, for example, by observing a cross section, using an electron microscope, such as a scanning electron microscope.

[0048] The total amount of the binder is not particularly limited and an amount conventionally used in the art can be used. For example, the total weight of the binder can be 1-10 wt%, such as 1-5 wt%, based on the total dry weight of the self-supporting electrode film.

[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 polyethylene has a melting point in the range of 85-150 °C, preferably 110-140 °C. The melting point can be determined by conventional methods in the art. For example, the melting point can be determined by differential scanning calorimetry (DSC) method.

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

[0052] In some embodiments, the polyethylene has a melt index in the range of 0.1-100 g / 10 min, preferably 10-30 g / 10 min, determined 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 homopolymer, polypropylene copolymer, such as chlorinated polypropylene.

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

[0055] In some embodiments, the polypropylene has a glass transition temperature in the range of -20 °C to 10 °C. As previously mentioned, the glass transition temperature can be determined by differential scanning calorimetry method, e.g. according to ASTM D3418-2015.

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

[0057] In the present application, the binder can include one or more of 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 adipate), 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, gelatin, and beeswax, in addition to polyethylene / polypropylene.

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

[0059] The present application does not have a particular requirement for the type and content of the electrode active material, and an electrode active material of a type and amount conventionally used in the art can be used. For example, the electrode active material can be various electrode active materials as described below in the "Energy storage device" section. For example, the amount of the electrode active material can be 70-99% by weight, for example, 80-95% by weight, based on the total dry weight of the self-supporting electrode film.

[0060] The present application does not have a particular requirement for the conductive agent used, and a type of conductive agent conventionally used in the art can be used. As an example, the conductive agent can be selected from one or more of graphite, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. Furthermore, as an example, the amount of the conductive agent can be 0.5-15.0% by weight, for example, 2.0-5.0% by weight, based on the total dry weight of the self-supporting electrode film.

[0061] Energy storage device

[0062] A second aspect of the present application provides an energy storage device including the electrode according to the first aspect of the present application.

[0063] The electrode may be the positive electrode and / or the 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 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 structure lithium phosphate, preferably 、 、 、 、 、 、 and One or more of; the negative electrode active material can be, for example, selected from one or more of natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon-based materials, tin-based materials, lithium titanate and metallic lithium, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composites and silicon alloys.

[0065] In some embodiments, the energy storage device may be a sodium ion secondary battery. For a sodium ion secondary battery, the positive electrode active material may be selected from one or more of a layered transition metal oxide or a Prussian blue analogue, preferably 、 、 、 、 and One or more of; the negative electrode active material can be, for example, selected from one or more of natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon-based materials and tin-based materials, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composites and silicon alloys.

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

[0067] In the present application, the energy storage device can be prepared by assembling various components including the electrode of the present application or the electrode prepared by the electrode preparation method of the present application in accordance with the method conventionally used in the art. For example, in the case of a secondary battery, the positive electrode, the negative electrode, and the separator therebetween can be assembled by the conventional method in the art, and then the electrolyte can be injected, and the process of sealing and the like can be performed, and thus the secondary battery can be prepared, and thus further description will not be provided herein.

[0068] The present application does not particularly require the type of the separator, and any separator conventionally used in the art can be used. For example, the material of the separator can be selected from one or more of polyethylene, polypropylene, polyethylene terephthalate, polyimide, polyamide, and polyphenylene terephthalamide; the separator can be a single layer or a multi-layer; and the separator can be optionally surface-modified (e.g., modified at a single surface or both surfaces), for example, coated with a ceramic layer.

[0069] The present application does not particularly require the type of the electrolyte, and the type of the electrolyte conventionally used in the art can be used. As an example, the following will be described with respect to a lithium ion secondary battery.

[0070] For the lithium ion secondary battery, the electrolyte can be a non-aqueous liquid electrolyte including an organic solvent and an electrolyte lithium salt.

[0071] In some embodiments, the organic solvent can be selected from one or more of ethylene carbonate (EC), vinylene carbonate (VC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), 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 can be selected from lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroborate (LiBF6), lithium bisfluorosulfonylimide (LiFSI), lithium bistrifluoromethylsulfonylimide (LiTFSI), lithium trifluoromethylsulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium bisoxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), one or more of lithium difluorooxalate phosphate (LiD FOP) and lithium tetrafluorooxalate 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 also optionally includes an additive. As an example, the additive can include an additive that facilitates negative electrode film formation or an additive that facilitates positive electrode film formation, and can also include an additive that improves battery performance, for example, an additive that improves battery performance at high or low temperatures, etc.

[0075] For lithium ion secondary batteries, the electrolyte can also be a gel electrolyte, a solid-state electrolyte, which are not described here again.

[0076] Electrode production system

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

[0078] (a) a feed module for providing an electrode active material, a conductive agent, and a binder;

[0079] (b) a mixing module downstream of the (a) feed module for mixing the electrode active material, the conductive agent, and the binder;

[0080] (c) a pre-forming module downstream of the (b) mixing module for pre-forming the mixture obtained from the mixing module to obtain a pre-formed self-supporting electrode film;

[0081] (d) a current collector providing module for providing a current collector;

[0082] (e) a compounding module downstream of the (c) pre-forming module and the (d) current collector providing module for compounding the pre-formed self-supporting electrode film and the current collector;

[0083] (f) an optional heat treatment module between the (c) pre-forming module and the (e) compounding module; and

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

[0085] Figure 1 A schematic diagram of one embodiment of the electrode production system of the present application. See Figure 1The electrode production system of the present application comprises a feeding module 100, a mixing module 200, a pre-forming module 301, an optional heat treatment module 302, a current collector providing module 401, a compounding module 501 and an optional temperature control module (not shown). In a typical embodiment, the feeding module 100 provides electrode active materials, conductive agents and binders to the mixing module 200; the mixing module mixes the provided raw materials and then sends the mixed mixture to the pre-forming module 301 by a conveying device for rolling to manufacture a pre-formed self-supporting electrode film; then sends it to the optional heat treatment module 302 by a conveying device for heat treatment; after the heat treatment module heat treats the pre-formed self-supporting electrode film, it is sent to the compounding module 501 by a conveying device to compound the pre-formed self-supporting electrode film and the current collector from the current collector providing module 401, thereby obtaining an electrode.

[0086] In the electrode production system of the present application, the heat treatment module can adopt (high temperature) standing, (high temperature) rolling or (high temperature) hot pressing for heat treatment. Figure 1 In the present application, the heat treatment module 302 is schematically shown to adopt (high temperature) rolling for heat treatment, for example, roll rolling, wherein the temperature of the upper roll is preferably equal to that of the lower roll. Alternatively, the heat treatment module 302 can also adopt (high temperature) standing or (high temperature) hot pressing for heat treatment. For details of the operation of the heat treatment module 302, see the description below in the electrode preparation method.

[0087] It is easy for those skilled in the art to understand that, in addition to the above-mentioned modules, the electrode production system of the present application can also optionally comprise other modules, for example, a slitting module (not shown) for slitting the prepared electrode, etc. Those skilled in the art can make routine settings as needed, which are not described here again.

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

[0089] Electrode preparation method

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

[0091] Step (i): providing electrode active materials, conductive agents and binders, wherein the binders comprise at least 30 wt%, preferably at least 50 wt%, more preferably at least 60 wt%, further preferably at least 80 wt%, for example 80-100 wt% of polyethylene and / or polypropylene based on the total dry weight of the binders;

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

[0093] Step (iii): obtaining an electrode from the mixture obtained in step (ii),

[0094] wherein step (iii) comprises:

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

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

[0097] and step (iii) comprises a heat treatment process, wherein the heat treatment temperature T of the heat treatment process in °C v satisfies: m T < T , preferably ,

[0098] wherein the heat treatment process is carried out during step (iii-1), or during step (iii-2), or independently from step (iii-1) and step (iii-2), for example between step (iii-1) and step (iii-2).

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

[0100] The individual steps of the electrode preparation method of the present application will be described below.

[0101] Step (i)

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

[0103] The types and amounts of the electrode active material, the conductive agent and the binder can be referred to the description above, which will not be repeated here.

[0104] It should be noted that the skilled person in the art can add various additives commonly used in the art, such as thickening agents, film-forming accelerators, etc., according to the needs during the preparation of the self-supporting electrode film.

[0105] Step (ii)

[0106] Step (ii) mixing the electrode active material, the electrically conductive agent, and the binder for the subsequent step.

[0107] The electrode production method of the present application does not have a particular requirement for the mixing method, and a mixing method commonly used in the art can be used, for example, mixing can be performed by one or more of stirring, ball milling, jet milling, high-speed shearing machine, or mechanical milling. As an example, a person skilled in the art can mix by a planetary ball mill or mechanical stirring. For example, when mixing is performed by mechanical stirring, the rotation speed of the mechanical stirring can be controlled to be 50-10000 rpm, for example, 50 rpm, 100 rpm, 300 rpm, 500 rpm, 1000 rpm, 2000 rpm, 3000 rpm, 5000 rpm, 8000 rpm, 10000 rpm, or a range defined by any two of them, and / or the mixing time is 5-720 minutes, for example, 5 minutes, 30 minutes, 60 minutes, 120 minutes, 240 minutes, 300 minutes, 360 minutes, 420 minutes, 720 minutes, or a range defined by any two of them. In addition, for example, zirconium oxide can be used as a ball milling medium, and the volume fraction of zirconium oxide is less than 30%.

[0108] Step (iii)

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

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

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

[0112] and step (iii) comprises a heat treatment process, 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: , preferably ,

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

[0114] In some embodiments, step (iii-1) is performed by way of calendering. Preferably, during the calendering, the lower roll temperature is set in the range of 100-180°C, and the upper roll temperature is set in the range of 100-160°C. Preferably, the upper roll temperature is equal to the lower roll temperature. As an example, the lower roll temperature can be 100, 110, 120, 130, 140, 150, 160, 170, 180°C, or a range defined by any two of them, and the upper roll temperature can be 100, 110, 120, 130, 140, 150, 160°C, or a range defined by any two of them. Further details regarding the calendering can be found by those skilled in the art as needed in the conventional manner, which will not be repeated here.

[0115] The present application does not have a particular requirement for the way of compounding in step (iii-2), and the way of compounding commonly used by those skilled in the art can be used. For example, compounding can be performed by way of calendering, such as calendering. When compounding is performed by way of calendering, the current collector is preferably attached to the lower roll, the self-supporting electrode film is attached to the upper roll, and the lower roll temperature is higher than or equal to the upper roll temperature. For example, the lower roll temperature can be in the range of 100-180°C, and / or the upper roll temperature can be in the range of 70-150°C. For example, the lower roll temperature can be 100, 100, 110, 120, 130, 140, 150, 160, 170, 180°C, or a range defined by any two of them, and / or the upper roll temperature can be 70, 80, 90, 100, 110, 120, 130, 140, 150°C, or a range defined by any two of them.

[0116] When the heat treatment is performed during step (iii-1) or during step (iii-2), and different temperatures of the upper and lower rolls are used, the heat treatment temperature refers to the temperature of the roll with higher temperature, such as the temperature of the lower roll.

[0117] Alternatively, the current collector can also be sputtered onto the self-supporting electrode film by way of magnetron sputtering. Alternatively, the current collector can also be electrodeposited onto the self-supporting electrode film by way of electrodeposition. The magnetron sputtering and electrodeposition can be performed by the way commonly used by those skilled in the art, which will not be repeated here.

[0118] The present application does not have a particular requirement for the type of current collector, and the type of current collector commonly used in the art can be used. For example, for the positive electrode, aluminum foil, nickel foil, or composite current collector, etc. can be used; for the negative electrode, copper foil or composite current collector, etc. can be used.

[0119] The inventors have found in their research that when step (iii) includes a heat treatment process, and the heat treatment temperature T vthe melting point T of the binder in °C m satisfies When the self-supporting electrode film of the electrode prepared by the preparation method of the present application has a high tensile strength in the length direction, and the electrode has excellent initial coulomb efficiency, high discharge specific capacity and excellent cycle performance. Further, when the heat treatment process has a heat treatment temperature T v the melting point T of the binder in °C m satisfies When the self-supporting electrode film of the electrode prepared by the preparation method of the present application has a high tensile strength in the length direction, and the electrode has excellent initial coulomb efficiency, high discharge specific capacity and excellent cycle performance. Further, when the heat treatment process has a heat treatment temperature T v may be in the range of 100, 110, 120, 130, 140, 150, 160, 170, 180 °C, or any two of them.

[0120] In preferred embodiments, the heat treatment process can be performed independently of step (iii-1) and step (iii-2), for example, between step (iii-1) and step (iii-2).

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

[0122] In some embodiments, the heat treatment process is performed by standing, and the heat treatment temperature T v satisfies .

[0123] The inventors have found that, in the case where the heat treatment process is performed by standing, when the heat treatment temperature T v satisfies , compared with the electrode whose heat treatment temperature T v and standing time t1 do not satisfy the above correlation, the self-supporting electrode film of the electrode has an increased tensile strength in the length direction, and the electrode has improved initial coulomb efficiency, discharge specific capacity and cycle performance. For example, the standing time t1 in hours can be in the range defined by any two of: , , or .

[0124] In some embodiments, the heat treatment process is performed by rolling, and the heat treatment temperature T v satisfies , preferably .

[0125] Similarly, the inventors have found that, in the case where the heat treatment process is performed by rolling, for example, by roll-to-roll, when the heat treatment temperature T v satisfies , the tensile strength of the self-supporting electrode film of the obtained electrode in the length direction increases, and the first coulomb efficiency, the discharge specific capacity, and the cycle performance of the electrode are also improved. Further, when the heat treatment temperature T v does not satisfy the above correlation, the tensile strength of the self-supporting electrode film of the obtained electrode in the length direction increases, and the first coulomb efficiency, the discharge specific capacity, and the cycle performance of the electrode are also improved. Further, when the heat treatment temperature T v satisfies , the tensile strength of the self-supporting electrode film of the obtained electrode in the length direction further increases, and the first coulomb efficiency, the discharge specific capacity, and the cycle performance of the electrode are also further improved. Further, when the heat treatment temperature T , , , the rolling time t2 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 performed by roll-to-roll, preferably the upper roll temperature is equal to the lower roll temperature.

[0127] In some embodiments, the heat treatment process is performed by hot-pressing, and the heat treatment temperature T v satisfies in minutes.

[0128] Similarly, the inventors have found that, in the case where the heat treatment process is performed by hot-pressing, when the heat treatment temperature T v satisfies , the tensile strength of the self-supporting electrode film of the obtained electrode in the length direction increases, and the first coulomb efficiency, the discharge specific capacity, and the cycle performance of the electrode are also improved. Further, when the heat treatment temperature T v does not satisfy the above correlation, the tensile strength of the self-supporting electrode film of the obtained electrode in the length direction increases, and the first coulomb efficiency, the discharge specific capacity, and the cycle performance of the electrode are also improved. Further, when the heat treatment temperature T , , , 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 performed by hot pressing, and the pressure of the heat treatment process is 5-20 MPa. For example, the pressure of the heat treatment process can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 MPa, or within a range defined by any two of them.

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

[0131] In embodiments, when the roll-to-roll roll pressing is performed, the number of roll pressings can use the number of roll pressings commonly used by those skilled in the art, for example, 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 within a range defined by any two of them.

[0132] For the binder used in the preparation method of the present application, for example, polyethylene, polypropylene, the electrode material, for example, the electrode active material, etc., see the description in the electrode section above, which is not repeated here.

[0133] Electrode

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

[0135] All the above descriptions regarding the fourth aspect of the present application apply here, which are not repeated here.

[0136] Examples

[0137] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0138] Preparation Examples

[0139] Example 1

[0140] Preparation of positive electrode

[0141] (1) NCM523 (Cluder, ), Super P (conductive carbon black), linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130°C, density 0.918 g / cm 3 , glass transition temperature -120 ° C, melt index of 12 g / 10min) are mixed uniformly in a mass ratio of 93:3:4.

[0142] (2) The mixture obtained in (1) was rolled (the rolling method was hot rolling, the upper roller temperature was 100° C., the lower roller temperature was 100° C., and the rolling time was 60 seconds) to obtain a preformed self-supporting electrode film.

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

[0144] (4) The self-supporting electrode film obtained in (3) is compounded with aluminum foil through rolling (wherein the temperature of the upper roller is 80°C, the temperature of the lower roller (collector side, the same below) is 150°C, and the rolling time is 30 seconds) via the lower surface during the standing process of step (3) to obtain a positive electrode.

[0145] Preparation of negative electrode

[0146] (1) Gr (graphite), Super P (conductive carbon black), linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130 °C, density 0.918 g / cm 3 , glass transition temperature -120 ° C, melt index of 12 g / 10min) are mixed uniformly in a mass ratio of 95:2.5:2.5.

[0147] (2) The mixture obtained in (1) was rolled (the rolling method was hot rolling, the upper roller temperature was 100° C., the lower roller temperature was 100° C., and the rolling time was 60 seconds) to obtain a preformed self-supporting electrode film.

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

[0149] (4) The self-supporting electrode film obtained in (3) is compounded with the copper foil through rolling (wherein the upper roller temperature is 80°C, the lower roller temperature is 150°C, and the rolling time is 30 seconds) via the lower surface during the standing process of step (3) to obtain a negative electrode.

[0150] Note: The melting point was measured using a differential scanning calorimeter (manufacturer: TA INSTRUMENTS, model: Q5000IR) according to the following conditions: nitrogen atmosphere, temperature increase rate of 10°C / min, test temperature range of room temperature to 200°C. The solid-liquid phase transition temperature during the test was 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 under a load of 2.16 kg, and the melt index of polypropylene was determined according to ISO 1133-1:2022 at a temperature of 230°C under a load of 2.16 kg.

[0152] Glass transition temperature: According to ASTM D3418-2015 by differential scanning calorimetry with a temperature increase rate of 10°C / min from -120°C to 25°C, constant temperature for 1 h, and then a temperature decrease rate of 10°C / min from 25°C to -120°C. A second temperature increase was performed with a temperature increase rate of 10°C / min from -120°C to 25°C, constant temperature for 1 h, and then a temperature decrease rate of 10°C / min from 25°C to -120°C.

[0153] Example 2

[0154] Except that the standing temperature in step (3) during the preparation of the positive electrode and the negative electrode was changed to 120°C, the rest was the same as Example 1.

[0155] Example 3

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

[0157] Example 4

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

[0159] Example 5

[0160] Preparation of the positive electrode

[0161] (1) NCM523 (Columbus, MA-EN-CA-0020), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, Dow 4157, melting point 130°C, density 0.918 g / cm 3 , glass transition temperature -120°C, melt index 12 g / 10 min) were mixed in a mass ratio of 93:3:4.

[0162] (2) The mixture obtained in (1) was roll-pressed (roll-pressing method: hot roll-pressing, upper roll temperature: 100°C, lower roll temperature: 100°C, roll-pressing time: 60 seconds) to obtain a preformed self-supporting electrode film.

[0163] (3) The preformed self-supporting electrode film obtained in (2) was additionally roll-pressed, with an upper roll temperature of 100°C and a lower roll temperature of 100°C, for a roll-pressing time of 260 seconds.

[0164] (4) The product obtained in (3) was laminated with an aluminum foil by roll-pressing the lower surface during roll-pressing in step (3) with an upper roll temperature of 80°C and a lower roll temperature of 150°C, for a roll-pressing time of 30 seconds, to obtain a positive electrode.

[0165] Preparation of a negative electrode

[0166] (1) Gr (graphite), Super P (conductive carbon black), and linear low-density polyethylene (LLDPE, Dow Chemical 4157, melting point 130°C, density 0.918 g / cm 3 , glass transition temperature -120°C, melt index 12 g / 10 min) were mixed in a mass ratio of 95:2.5:2.5.

[0167] (2) The mixture obtained in (1) was roll-pressed (roll-pressing method: hot roll-pressing, upper roll temperature: 100°C, lower roll temperature: 100°C, roll-pressing time: 60 seconds) to obtain a preformed self-supporting electrode film.

[0168] (3) The preformed self-supporting electrode film obtained in (2) was additionally roll-pressed, with an upper roll temperature of 100°C and a lower roll temperature of 100°C, for a roll-pressing time of 260 seconds.

[0169] (4) The self-supporting electrode film obtained in (3) was laminated with a copper foil by roll-pressing the lower surface during roll-pressing in step (3) with an upper roll temperature of 80°C and a lower roll temperature of 150°C, for a roll-pressing time of 30 seconds, to obtain a negative electrode.

[0170] Example 6

[0171] Except that the heat treatment temperature in step (3) in the preparation of the positive electrode and the negative electrode (i.e., the upper roll temperature and the lower roll temperature of the roll-pressing, the same below) was changed to 120°C, the rest was the same as in Example 5.

[0172] Example 7

[0173] Except that the heat treatment temperature in step (3) in the preparation of the positive electrode and the negative electrode was changed to 120°C, and the roll-pressing time was changed to 240 seconds, the rest was the same as in Example 5.

[0174] Example 8

[0175] Except that the heat treatment temperature in step (3) during the preparation of the positive electrode and the negative electrode is changed to 180°C and the roll-pressing time is changed to 93 seconds, the rest is the same as Example 5.

[0176] Example 9

[0177] Except that the heat treatment temperature in step (3) during the preparation of the positive electrode and the negative electrode is changed to 180°C and the roll-pressing time is changed to 73 seconds, the rest is the same as Example 5.

[0178] Example 10

[0179] Except that the heat treatment temperature in step (3) during the preparation of the positive electrode and the negative electrode is changed to 160°C and the roll-pressing time is changed to 93 seconds, the rest is the same as Example 5.

[0180] Example 11

[0181] (1) NCM523 (Columbus, MA-EN-CA-0020), Super P (conductive carbon black), linear low density polyethylene (LLDPE, Dow 4157, melting point 130°C, density 0.918 g / cm 3 , glass transition temperature -120°C, melt index 12 g / 10 min) and PTFE (Japan Daikin F-104, melting point 344°C, density 2.18 g / cm 3 ) were mixed in a mass ratio of 93:3:2:2, wherein the melting point of the binder mixture was 130°C.

[0182] (2) The mixture obtained in (1) was roll-pressed (the roll-pressing method was hot roll-pressing, the upper roll temperature was 100°C, the lower roll temperature was 100°C, and the roll-pressing time was 60 seconds) to obtain a preformed 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 5h.

[0184] (4) The self-supporting electrode film obtained in (3) was compounded with an aluminum foil by roll-pressing (wherein the upper roll temperature was 80°C, the lower roll temperature was 150°C, and the roll-pressing time was 30 seconds) through the lower surface of the self-supporting electrode film during the standing process in step (3) to obtain a positive electrode.

[0185] Preparation of the negative electrode

[0186] (1) Gr (graphite), Super P (conductive carbon black), linear low density polyethylene (LLDPE, Dow 4157, melting point 130°C, density 0.918 g / cm 3, glass transition temperature -120°C, melt index 12 g / 10 min) and PTFE (Daikin Japan F-104, melting point 344°C, density 2.18 g / cm 3 ) were mixed in a mass ratio of 95: 2.5: 1.5: 1, and the melting point of the binder mixture was 130°C.

[0187] (2) The mixture obtained in (1) was roll-pressed (roll-pressing method: hot roll-pressing, upper roll temperature 100°C, lower roll temperature 100°C, roll-pressing time 60 seconds) to obtain a preformed 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 h.

[0189] (4) The self-supporting electrode film obtained in (3) was compounded with a copper foil by roll-pressing the lower surface during the standing process in step (3) (wherein the upper roll temperature was 80°C, the lower roll temperature was 150°C, and the roll-pressing time was 30 seconds) to obtain a negative electrode.

[0190] Example 12

[0191] Except that the standing temperature during the preparation of the positive electrode and the negative electrode was changed to 180°C and the standing time was changed to 2.56 h, the other conditions were the same as in Example 11.

[0192] Example 13

[0193] Preparation of a positive electrode

[0194] (1) NCM523 (Crouzet, MA-EN-CA-0020), Super P (conductive carbon black), linear low-density polyethylene (LLDPE, Dow Chemical 4157, melting point 130°C, density 0.918 g / cm 3 , glass transition temperature -120°C, melt index 12 g / 10 min), and PTFE (Daikin Japan F-104, melting point 344°C, density 2.18 g / cm 3 ) were mixed in a mass ratio of 93: 3: 2: 2, and the melting point of the binder mixture was 130°C.

[0195] (2) The mixture obtained in (1) was roll-pressed (roll-pressing method: hot roll-pressing, upper roll temperature 100°C, lower roll temperature 100°C, roll-pressing time 60 seconds) to obtain a preformed self-supporting electrode film.

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

[0197] (4) The self-supporting electrode film obtained in (3) was compounded with an aluminum foil by calendering the lower surface of the self-supporting electrode film during the calendering in step (3) (wherein the upper roll temperature was 80°C, the lower roll temperature was 150°C, and the calendering time was 30 seconds), to obtain a positive electrode.

[0198] Preparation of a negative electrode

[0199] (1) Gr (graphite), Super P (conductive carbon black), linear low-density polyethylene (LLDPE, Dow Chemical 4157, melting point 130°C, density 0.918 g / cm 3 , glass transition temperature -120°C, melt index 12 g / 10 min), and PTFE (Daikin F-104, melting point 344°C, density 2.18 g / cm 3 ) were mixed in a mass ratio of 95:2.5:1.5:1, wherein the melting point of the binder mixture was 130°C.

[0200] (2) The mixture obtained in (1) was calendered (the calendering method was hot calendering, the upper roll temperature was 100°C, the lower roll temperature was 100°C, and the calendering time was 60 seconds), to obtain a preformed self-supporting electrode film.

[0201] (3) The preformed self-supporting electrode film obtained in (2) was additionally calendered, wherein the upper roll temperature was 160°C, the lower roll temperature was 160°C, and the calendering time was 93 seconds.

[0202] (4) The self-supporting electrode film obtained in (3) was compounded with a copper foil by calendering the lower surface of the self-supporting electrode film during the calendering in step (3) (wherein the upper roll temperature was 80°C, the lower roll temperature was 150°C, and the calendering time was 30 seconds), to obtain a negative electrode.

[0203] Example 14

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

[0205] Example 15

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

[0207] Example 16

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

[0209] Example 17

[0210] Example 1 was repeated except that the standing time in step (3) in the preparation of the positive and negative electrodes was changed to 4 hours.

[0211] Example 18

[0212] Example 1 was repeated except that the standing time in step (3) in the preparation of the positive and negative electrodes was changed to 7 hours.

[0213] Example 19

[0214] Example 1 was repeated except that the standing time in step (3) in the preparation of the positive and negative electrodes was changed to 4 hours.

[0215] Example 20

[0216] Example 1 was repeated except that the standing time in step (3) in the preparation of the positive and negative electrodes was changed to 8 hours.

[0217] Example 21

[0218] Example 3 was repeated except that the standing time in step (3) in the preparation of the positive and negative electrodes was changed to 0.56 hours.

[0219] Example 22

[0220] Example 3 was repeated except that the standing time in step (3) in the preparation of the positive and negative electrodes was changed to 0.5 hours.

[0221] Example 23

[0222] Example 3 was repeated except that the standing time in step (3) in the preparation of the positive and negative electrodes was changed to 3 hours.

[0223] Example 24

[0224] Example 10 was repeated except that the rolling time in step (3) in the preparation of the positive and negative electrodes was changed to 135 seconds.

[0225] Example 25

[0226] Example 10 was repeated except that the rolling time in step (3) in the preparation of the positive and negative electrodes was changed to 115 seconds.

[0227] Example 26

[0228] Example 10 was repeated except that the rolling time in step (3) in the preparation of the positive and negative electrodes was changed to 15 seconds.

[0229] Example 27

[0230] Example 10 was repeated except that the rolling time in step (3) during the preparation of the positive and negative electrodes was changed to 10 seconds.

[0231] Example 28

[0232] Example 10 was repeated except that the rolling time in step (3) during the preparation of the positive and negative electrodes was changed to 150 seconds.

[0233] Example 29

[0234] Example 5 was repeated except that the rolling time in step (3) during the preparation of the positive and negative electrodes was changed to 360 seconds.

[0235] Example 30

[0236] Example 5 was repeated except that the rolling time in step (3) during the preparation of the positive and negative electrodes was changed to 340 seconds.

[0237] Example 31

[0238] Example 5 was repeated except that the rolling time in step (3) during the preparation of the positive and negative electrodes was changed to 45 seconds.

[0239] Example 32

[0240] Example 8 was repeated except that the rolling time in step (3) during the preparation of the positive and negative electrodes was changed to 9 seconds.

[0241] Example 33

[0242] Example 10 was repeated except that the linear low density polyethylene was replaced by the corresponding weight parts of chlorinated polypropylene (PP-C, Yangzi Petrochemical-BASF Limited Liability Company, R370Y, melting point 128°C, density 1.3 g / cm 3 , glass transition temperature -10°C, melt index 9 g / 10 min).

[0243] Example 34

[0244] Example 10 was repeated except that the linear low density polyethylene was replaced by the corresponding weight parts of high density polyethylene (HDPE, Yangzi Petrochemical-BASF Limited Liability Company, 5000S, melting point 131°C, density 1.3 g / cm 3 , glass transition temperature -125°C, melt index 22 g / 10 min).

[0245] Example 35

[0246] Except that the linear low-density polyethylene was replaced by the corresponding weight parts of low-density polyethylene (LDPE, Iran Petrochemical 2420D, melting point 125 ° C, density 1.3 g / cm 3 , glass transition temperature -100 ° C., and melt index of 20 g / 10 min), the rest is the same as Example 10.

[0247] Example 36

[0248] Preparation of positive electrode

[0249] (1) NCM523 (Cruder, MA-EN-CA-0020), Super P (conductive carbon black), linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130 °C, density 0.918 g / cm 3 , glass transition temperature -120 ° C, melt index of 12 g / 10min) are mixed uniformly in a mass ratio of 93:3:4.

[0250] (2) The mixture obtained in (1) was roll-pressed (the rolling method was hot rolling, the upper roller temperature was 100° C., the lower roller temperature was 100° C., and the rolling time was 60 seconds) to obtain a preformed self-supporting electrode film.

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

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

[0253] Preparation of negative electrode

[0254] (1) Gr (graphite), Super P (conductive carbon black), linear low-density polyethylene (LLDPE, DowDuPont 4157, melting point 130 °C, density 0.918 g / cm 3 , glass transition temperature -120 ° C, melt index of 12 g / 10min) are mixed uniformly in a mass ratio of 95:2.5:2.5.

[0255] (2) The mixture obtained in (1) was roll-pressed (the rolling method was hot rolling, the upper roller temperature was 100° C., the lower roller temperature was 100° C., and the rolling time was 60 seconds) to obtain a preformed self-supporting electrode film.

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

[0257] (4) The self-supporting electrode film obtained in (3) is compounded with a copper foil by roll pressing (wherein the upper roll temperature is 80°C, the lower roll temperature is 150°C, and the roll pressing time is 30 seconds) from the lower surface during the heat pressing process in step (3), to obtain a negative electrode.

[0258] Example 37

[0259] Except that the heat pressing temperature in step (3) in the process of preparing the positive electrode and the negative electrode is changed to 120°C, the rest is the same as Example 36.

[0260] Example 38

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

[0262] Example 39

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

[0264] Example 40

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

[0266] Example 41

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

[0268] Example 42

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

[0270] Example 43

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

[0272] Example 44

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

[0274] Example 45

[0275] Except that the hot-pressing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 160°C and the hot-pressing time was changed to 3.98 minutes, the rest was the same as in Example 36.

[0276] Example 46

[0277] Except that the hot-pressing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 180°C and the hot-pressing time was changed to 0.73 minutes, the rest was the same as in Example 36.

[0278] Example 47

[0279] Except that the hot-pressing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 180°C and the hot-pressing time was changed to 0.15 minutes, the rest was the same as in Example 36.

[0280] Example 48

[0281] Except that the pressure in step (3) in the process of preparing the positive and negative electrodes was changed from 5 MPa to 20 MPa, the rest was the same as in Example 40.

[0282] Example 49

[0283] Except that the pressure in step (3) in the process of preparing the positive and negative electrodes was changed from 5 MPa to 20 MPa, the rest was the same as in Example 42.

[0284] Example 50

[0285] Except that the pressure in step (3) in the process of preparing the positive and negative electrodes was changed from 5 MPa to 20 MPa, the rest was the same as in Example 46.

[0286] Example 51

[0287] Except that the pressure in step (3) in the process of preparing the positive and negative electrodes was changed from 5 MPa to 20 MPa, the rest was the same as in Example 45.

[0288] Example 52

[0289] Except that the hot-pressing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 100°C, the rest was the same as in Example 36.

[0290] Example 53

[0291] Except that the hot-pressing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 120°C and the hot-pressing time was changed to 8 minutes, the rest was the same as in Example 36.

[0292] Example 54

[0293] Except that the hot-pressing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 160°C and the hot-pressing time was changed to 4.5 minutes, it was the same as Example 36.

[0294] Example 55

[0295] Except that the hot-pressing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 180°C and the hot-pressing time was changed to 1 minute, it was the same as Example 36.

[0296] Comparative Example 1

[0297] Except that step (3) was not performed in the process of preparing the positive and negative electrodes, it was the same as Example 1.

[0298] Comparative Example 2

[0299] Except that the standing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 90°C, it was the same as Example 1.

[0300] Comparative Example 3

[0301] Except that the standing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 190°C, it was the same as Example 3.

[0302] Comparative Example 4

[0303] Except that the heat-treatment temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 90°C, it was the same as Example 5.

[0304] Comparative Example 5

[0305] Except that the heat-treatment temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 190°C, it was the same as Example 8.

[0306] Comparative Example 6

[0307] Except that the hot-pressing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 90°C, it was the same as Example 41.

[0308] Comparative Example 7

[0309] Except that the hot-pressing temperature in step (3) in the process of preparing the positive and negative electrodes was changed to 184°C, it was the same as Example 47.

[0310] Measurement Example

[0311] 1. Electrochemical performance measurement method

[0312] Assembly of full cells

[0313] The positive and negative electrodes prepared in 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 the electrolyte ( In a solution in a mixture of DEC:EC with a volume ratio of 1:1 (the solution also contains 10 volume % of FEC and 1 volume % of VC based on the total volume of the solution), A full cell was assembled (with a concentration of 1M) (the ratio of the theoretical capacity of the negative electrode to the theoretical capacity of the positive electrode, N / P, was 1.1). A positive electrode gasket, positive electrode sheet, separator, negative electrode sheet, and negative electrode spring were placed from bottom to top within the positive electrode casing. Electrolyte was injected, and the negative electrode casing was snapped in place and pressed to form a button cell. The positive and negative electrode casings, gaskets, and springs used were made of stainless steel and purchased from Dongguan Kelude Laboratory Equipment Technology Co., Ltd.

[0314] First coulombic efficiency and discharge specific capacity

[0315] The assembled full cell was first activated at 30°C. The cell was charged to 2.7V at a 0.1C rate, then allowed to rest for 10 minutes. It was then discharged to 4.2V at a 0.1C rate and allowed to rest for 10 minutes. This cycle was repeated five times to complete the activation process. Starting from the sixth cycle, the charge and discharge rates were adjusted to 0.2C / 0.5C.

[0316] Record the charge capacity and discharge capacity of the first cycle (activation), divide the discharge capacity by the charge capacity, and then multiply by 100% to get the first coulombic efficiency.

[0317] The activated full battery is charged and discharged for n-5 cycles under the same charge and discharge conditions as the sixth cycle to obtain the discharge and charge capacities at cycle n. The discharge capacity at each cycle is divided by the mass of the positive electrode active material in the battery to obtain the specific discharge capacity (the data in Table 2 are the specific discharge capacities at cycles 1 and 50).

[0318] 2. Other property measurement methods

[0319] tensile strength

[0320] The tensile strength of the self-supporting film in the longitudinal 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 in the length direction of the positive self-supporting electrode film and the negative self-supporting electrode film before and after " / " respectively.

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

[0327] Specifically, it can be seen from Comparative Example 1, Inventive Example 5 and Inventive Example 36 that, compared with Comparative Example 1 (tensile strength of 0.12 / 0.13 MPa) which does not perform heat treatment, the self-supporting electrode films of Inventive Example 1, Inventive Example 5 and Inventive Example 36 have greater tensile strength in the length direction (0.26 / 0.27 MPa, 0.28 / 0.30 MPa and 0.32 / 0.34 MPa respectively), and the first coulombic efficiency, the first discharge gram capacity and the discharge gram capacity after 50 cycles (the above performance parameters of Inventive Example 1 are 80.4%, 132.1 mAh / g and 113.6 mAh / g respectively, the above performance parameters of Inventive Example 5 are 82%, 132.5 mAh / g and 102.4 mAh / g respectively, and the above performance parameters of Inventive Example 36 are 76.4%, 120.1 mAh / g and 108.2 mAh / g respectively) are all 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 shows that performing a separate heat treatment (stationary, rolling or hot pressing, etc.) in addition to the pre-forming and compounding process is beneficial to improving the tensile strength in the length direction of the obtained self-supporting electrode film, and improving the first coulombic efficiency, the first discharge gram capacity and the cycle performance of the obtained electrode.

[0328] Comparing Example 1 and Example 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 the heat treatment of Example 1 is 100°C, while the static temperature during the heat treatment of Comparative Example 2 is 90°C. The tensile strength (0.26 / 0.27 MPa) and electrochemical properties (80.4%, 132.1 mAh / g and 113.6mAh / g) are significantly better than Comparative Example 2 (the tensile strength in the length direction is 0.13 / 0.15MPa, and the electrochemical performance test results are 67.2%, 112mAh / g and 72.3mAh / g, respectively); the difference between Example 3 and Comparative Example 3 is that the static temperature during the heat treatment of Example 3 is 180°C, while the static temperature during the heat treatment of Comparative Example 3 is 190°C. The tensile strength in the length direction (0.25 / 0.27MPa) and electrochemical performance (79.4%, 127.2mAh / g and 99.9mAh / g) of Example 3 are significantly better than Comparative Example 3 (the tensile strength in the length direction is 0.13 / 0.19MPa, and the electrochemical performance test results are 70%, 110mAh / g and 70mAh / g, respectively). Similar patterns can be found by comparing Example 5 and Example 8 with Comparative Examples 4 and 5, and by comparing Example 41 and Example 47 with Comparative Examples 6-7. This shows that compared with the heat treatment temperature T v The melting point T of the binder in °C m Dissatisfied In the case of heat treatment temperature T in °C v The melting point T of the binder in °C m When this correlation is met, the self-supporting electrode film of the obtained electrode has greater tensile strength in the length direction, and better first coulombic efficiency, first discharge gram capacity and cycle performance (discharge gram capacity after 50 cycles).

[0329] Comparing Example 1 and Examples 18-20, it can be seen that the standing time of Example 1 is 5 hours, while the standing time of Example 19 is 4 hours, the tensile strength of the self-supporting electrode film of the electrode obtained in Example 1 in the length direction (0.26 / 0.27 MPa) is greater than that of the self-supporting electrode film of the electrode obtained in Example 19 in the length direction (0.18 / 0.18 MPa), and the electrochemical performance of Example 1 (80.4%, 132.1 mAh / g and 113.6 mAh / g) is better than that of Example 19 (71.2%, 101.2 mAh / g and 84.9 mAh / g); the standing time of Example 18 is 7 hours, while the standing time of Example 20 is 8 hours, the tensile strength of the self-supporting electrode film of the electrode obtained in Example 18 in the length direction (0.27 / 0.30 MPa) is greater than that of the self-supporting electrode film of the electrode obtained in Example 20 in the length direction (0.18 / 0.19 MPa), and the electrochemical performance of Example 18 (81.4%, 132.9 mAh / g and 114.8 mAh / g) is better than that of Example 20 (72.5%, 101.8 mAh / g and 85.5 mAh / g). Similar rules can also be found for other examples, for example, Examples 4 and Examples 14-17, or Examples 3 and Examples 21-23, which are also heat treated in a standing manner; for Examples, for example, Examples 5 and Examples 29-31, or Examples 10 and Examples 24-28, which are heat treated in a rolling manner; for Examples, for example, Examples 37, Examples 42-43 and Example 53, or Examples 38, Examples 44-45 and Example 54, or Examples 46-47 and Example 55, which are heat treated in a hot-pressing manner. This shows that, when the heat treatment temperature and the heat treatment time satisfy a specific correlation (for example, for heat treatment in a standing manner, the heat treatment temperature T v and the standing time t1 in hours satisfy: ; for heat treatment in a rolling manner, the heat treatment temperature T v and the rolling time t2 in seconds satisfy: ; for heat treatment in a hot-pressing manner, the heat treatment temperature T v and the hot-pressing time t3 in minutes satisfy: , compared with the case where the above correlation is not satisfied, the self-supporting electrode film of the obtained electrode has greater tensile strength in the length direction, and has better first coulombic efficiency, first discharge gram capacity and cycle performance (discharge gram capacity after 50 cycles).

[0330] In addition, 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 the heat treatment temperature Tv a relationship between the melting point T m of the binder (for example ), or a relationship between the heat treatment temperature T v and the rolling time t2(for example ), can further improve the tensile strength of the self-supporting electrode film of the obtained electrode in the length direction, and the sub-Coulomb efficiency, the initial discharge capacity, and the cycle performance.

[0331] In addition, it can also be seen from Examples 11-13 and Examples 33-35 that the above rules are also applicable to the case of using different binders or using a mixture of multiple binders.

[0332] The above only describes exemplary embodiments of the present application. It should be noted that, for those skilled in the art, improvements can be made to the present application without departing from the inventive concept, and these all fall within the scope of protection of the present application.

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 wt %, preferably at least 50 wt %, more preferably at least 60 wt %, further preferably at least 80 wt %, for example 80-100 wt % 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, for example 0.20 MPa or more, or 0.25 MPa or more, or 0.30 MPa or more.

2. The electrode of claim 1, wherein the binder comprises no more than 50 wt% polytetrafluoroethylene, based on the total dry weight of the binder, such as comprising no polytetrafluoroethylene.

3. The electrode according to claim 1 or 2, wherein the binder consists of polyethylene and / or polypropylene.

4. The electrode according to any one of claims 1 to 3, wherein one or more of the following conditions are met: (1) at least a portion of the polyethylene and / or polypropylene is formed into fibers; and (2) At least a portion of the polyethylene and / or polypropylene forms fibers and the formed fibers are formed in the thickness direction of the self-supporting electrode film. Within 45°, e.g. Within 30°, e.g. Oriented fibers with an orientation within 15°.

5. The electrode according to any one of claims 1 to 4, wherein one or more of the following conditions are met: (3) the total weight of the binder accounts for 1-10% by weight of the total dry weight of the self-supporting electrode film, for example, 1-5% by weight; (4) 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, and preferably the polyethylene is selected from polyethylene homopolymer or polyethylene copolymer; (5) The melting point of the polyethylene is in the range of 85-150°C, preferably 110-140°C; (6) The glass transition temperature of the polyethylene is -120°C to -70°C, preferably -120°C to -90°C; (7) The polyethylene has a melt index in the range of 0.1-100 g / 10 min, preferably 10-30 g / 10 min, measured at a temperature of 190° C. and a load of 2.16 kg according to ISO 1133-1:2022; (8) The polypropylene is selected from one or more of polypropylene homopolymers and polypropylene copolymers, such as chlorinated polypropylene; (9) The melting point of the polypropylene is in the range of 105-180°C, preferably 120-150°C; (10) The glass transition temperature of the polypropylene is between -20°C and 10°C; (11) the polypropylene has a melt index in the range of 0.3-100 g / 10 min, preferably 1-20 g / 10 min, measured at a temperature of 230° C. and a load of 2.16 kg according to ISO 1133-1:2022; and (12) In addition to polyethylene / polypropylene, the binder also includes one or more of 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, polylactic 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, polyoxymethylene, polyphenylene sulfide, paraffin, gelatin, and beeswax.

6. An energy storage device comprising the electrode according to any one of claims 1 to 5.

7. The energy storage device according to claim 6, wherein any one of the following conditions is met: (13) The energy storage device is a lithium ion secondary battery. Preferably, the positive electrode active material is selected from one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and olivine structure lithium phosphate, preferably 、 、 、 、 、 、 and One or more of Preferably, the negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon-based materials, tin-based materials, lithium titanate and metallic lithium, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composites and silicon alloys; or (14) The energy storage device is a sodium ion secondary battery. Preferably, the positive electrode active material is selected from one or more layered transition metal oxides or Prussian blue analogs, preferably 、 、 、 、 and One or more of Preferably, the negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon-based materials and tin-based materials, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composites and silicon alloys; or (15) The energy storage device is a supercapacitor. Preferably, the positive electrode active material is selected from one or more of metal oxides, conductive polymers and carbon materials. 、NiO、 , one or more of polyaniline, polypyrrole, activated carbon, graphene and biochar, Preferably, the negative electrode active material is selected from one or more of metals, carbon materials, conductive polymers, metal oxides, metal organic framework (MOF) derived materials, preferably aluminum, zinc, activated carbon, graphite, polyaniline, polypyrrole, polythiophene and One or more of .

8. An electrode production system comprising: (a) a feeding module for providing electrode active materials, a conductive agent, and a binder; (b) a mixing module, located downstream of the feeding module (a), for mixing the electrode active material, the conductive agent and the binder; (c) a preforming module, located downstream of the mixing module (b), for preforming the mixture obtained by the mixing module to obtain a preformed self-supporting electrode film; (d) a current collector providing module, used to provide a current collector; (e) a composite module, located downstream of the (c) preforming module and the (d) current collector providing module, for composite the preformed self-supporting electrode film and the current collector; (f) an optional heat treatment module located between the (c) preforming module and the (e) composite module; and (g) An optional temperature control module for displaying and controlling the temperature of the (f) heat treatment module.

9. An electrode preparation method comprising: Step (i): providing an electrode active material, a conductive agent and a binder, wherein the binder comprises at least 30 wt %, preferably at least 50 wt %, more preferably at least 60 wt %, further preferably at least 80 wt %, for example 80-100 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): preforming the mixture obtained in step (ii) to obtain a preformed self-supporting electrode film; and Step (iii-2): providing a current collector, and compounding the current collector with the preformed self-supporting electrode film obtained in the previous step, And step (iii) comprises a heat treatment process, wherein the heat treatment temperature T in ° C. v The melting point T of the binder in °C m satisfy: , preferably , The heat treatment process is carried out during step (iii-1), or during step (iii-2), or independently of step (iii-1) and step (iii-2), for example, between step (iii-1) and step (iii-2). 10 . The electrode preparation method according to claim 9 , wherein the heat treatment process is performed by standing, rolling or hot pressing.

11. The electrode preparation method according to any one of claims 9 to 10, wherein the heat treatment process is performed by standing still, and the heat treatment temperature T in ° C. v With the rest time t1 in hours: .

12. The electrode preparation method according to any one of claims 9 to 11, wherein the heat treatment process is performed by roller pressing, and the heat treatment temperature T in ° C. v The rolling time t2 in seconds satisfies: , preferably . 13 . The electrode preparation method according to claim 12 , wherein the roller pressing is double-roll pressing, and preferably the temperature of the upper roller is equal to the temperature of the lower roller.

14. The electrode preparation method according to any one of claims 9 to 13, wherein the heat treatment process is performed by hot pressing, and the heat treatment temperature T in ° C. v The hot pressing time t3 in minutes satisfies: ; Preferably, the hot pressing pressure is 5-20MPa.

15. The preparation method according to any one of claims 9 to 14, wherein one or more of the following conditions are met: (a) the binder comprises at least 30 wt%, preferably at least 50 wt%, more preferably at least 60 wt%, further preferably at least 80 wt%, e.g. 80-100 wt% of polyethylene and / or polypropylene, based on the total dry weight of the binder; (b) the total weight of the binder accounts for 1-10 wt %, such as 1-5 wt %, of the total dry weight of the self-supporting electrode film; (c) 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 the polyethylene is selected from polyethylene homopolymer or polyethylene copolymer; (d) the polyethylene has a melting point in the range of 85-150°C, preferably 110-140°C; (e) the glass transition temperature of the polyethylene is from -120°C to -70°C, preferably from -120°C to -90°C; (f) the polyethylene has a melt index in the range of 0.1-100 g / 10 min, preferably 10-30 g / 10 min, measured at a temperature of 190° C. and a load of 2.16 kg according to ISO 1133-1:2022; (g) the polypropylene is selected from one or more of a polypropylene homopolymer and a polypropylene copolymer, such as chlorinated polypropylene; (h) the melting point of the polypropylene is in the range of 105-180°C, preferably 120-150°C; (i) the glass transition temperature of the polypropylene is from -20°C to 10°C; (j) the polypropylene has a melt index in the range of 0.3-100 g / 10 min, preferably 1-20 g / 10 min, measured at a temperature of 230° C. and a load of 2.16 kg according to ISO 1133-1:2022; (k) in addition to polyethylene / polypropylene, the binder further comprises one or more of 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, 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, polyoxymethylene, polyphenylene sulfide, paraffin, gelatin, and beeswax; (1) The energy storage device is a lithium ion secondary battery, and preferably, the positive electrode active material is selected from one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and olivine structure lithium phosphate, preferably 、 、 、 、 、 、 and One or more of Preferably, the negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon-based materials, tin-based materials, lithium titanate and metallic lithium, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composites and silicon alloys; or (m) The energy storage device is a sodium ion secondary battery. Preferably, the positive electrode active material is selected from one or more of layered transition metal oxides or Prussian blue analogs, preferably 、 、 、 、 and One or more of Preferably, the negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon-based materials and tin-based materials, preferably one or more of graphite and silicon-based materials, more preferably one or more of graphite, silicon-carbon composites and silicon alloys; or (n) The energy storage device is a supercapacitor, preferably, the positive electrode active material is 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, Preferably, the negative electrode active material is selected from one or more of metals, carbon materials, conductive polymers, metal oxides, metal organic framework (MOF) derived materials, preferably aluminum, zinc, activated carbon, graphite, polyaniline, polypyrrole, polythiophene and One or more of .

16. An electrode prepared by the preparation method according to any one of claims 9 to 15.

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