Method for exfoliating a composite

Abstract

The present invention provides a method for stripping a composite by immersing the composite in a stripping solution, wherein the composite comprises a metal substrate and a coating applied to one or both sides of the metal substrate, wherein the coating comprises a polymer binder, and wherein the polymer binder comprises an aqueous copolymer. Using a stripping solution comprising a strong base allows for complete stripping of the composite in an efficient and extremely fast manner. Furthermore, the stripping method disclosed herein avoids complex separation processes, contamination and corrosion of the metal substrate, and enables excellent material recovery. An application of a method for stripping the electrodes of a battery is disclosed herein.

Description

Field of the Invention

[0001] The present invention relates to the field of methods for recycling materials. In particular, the present invention relates to a method for delaminating a composite comprising a metal substrate and a coating applied to one or both sides of the metal substrate. Background Art

[0002] Increasing urbanization, the rapid development of technological innovation, and the consequent frequent replacement of products or disposal of waste consumables have led to a shortening of the product life cycle and / or overproduction of waste. With the emergence of increasingly serious problems associated with overproduction of waste, such as harmful effects on human health, adverse effects on the environment, and consumption of resources, there has been an urgent need worldwide to take prompt action to utilize various waste treatment methods to address these complex problems.

[0003] Recycling, as a key component in the waste hierarchy for reducing waste, aims to recover useful materials from waste for reuse. Recycling materials can conserve natural resources, reduce the energy consumption associated with raw material extraction (and thus the production cost), and reduce the environmental impact by reducing greenhouse gas and SO x emissions. Since material recycling can bring significant benefits, the development of efficient material recycling methods is crucial for achieving a circular economy.

[0004] The term "composite" refers to a metal substrate with a coating applied to one or both sides of the metal substrate, where the coating contains a polymer binder. The polymer binder is responsible for the adhesion between the coating and the metal substrate. Applying a coating on a metal substrate is a method of changing the surface properties to meet the performance requirements in various technical applications. Some applications of the coating include adhesives, formation of barrier layers, scratch and wear resistance, chemical resistance, wettability, and biocompatibility. Coating a metal substrate is often used in battery preparation, membrane technology, packaging materials, printed circuit boards, wires or cables, and biomedical applications. Therefore, separating the coating from the metal substrate is a widely applied technique in material recycling.

[0005] However, for products that have reached the end of their service life or waste products that can be immediately recycled during the production process, there are some difficulties in the step of separating the composites contained in the products into the coating and the metal substrate during the recycling process.

[0006] On the one hand, delamination of the composite may occur within the bulk of the coating rather than at the coating-metal substrate interface. The coating may not be completely delaminated from the metal substrate, and part of the coating may remain intact on the metal substrate. This will result in an undesired loss of coating material as it cannot be directly recovered from the delamination process, and the recycled metal substrate will have a high impurity content due to the presence of the residual coating, necessitating a subsequent separation process to be introduced.

[0007] On the other hand, delaminating the coating from the metal substrate can be very inefficient and take up to several hours. Prolonged exposure of the composite to severe delamination conditions is likely to cause side effects such as corrosion, dissolution, and damage of the materials within the composite (especially the metal substrate), as well as the generation of side reaction products.

[0008] Polymer binders commonly responsible for the adhesion between the coating and the metal substrate, such as polyvinylidene fluoride (PVDF), have drawbacks in that they are insoluble in water, and in fact, these polymers can only be dissolved in some specific organic solvents such as N-methyl-2-pyrrolidone (NMP). NMP is flammable and toxic, so special handling is required. An NMP recovery system must be installed during the drying process to recover NMP vapor. This will incur significant costs during the manufacturing process as establishing such a recovery system requires a large capital investment. Therefore, for applications where exposure to a humid environment during manufacturing is not a significant issue, in the present invention, polymer binders with cheaper and more environmentally friendly solvents (such as aqueous solvents, most commonly water) are preferably used as it can reduce the substantial capital cost of the recovery system.

[0009] Polymer binders suitable for water-based coatings exhibit excellent dispersibility and stability in water and can promote extremely strong coating-metal substrate adhesion. However, precisely due to the extremely strong coating-metal substrate adhesion that exists when using these polymer binders, it poses a great challenge to delaminate the water-based coating from the connected metal substrate. To better optimize the performance of these water-based binders, copolymers containing structural units derived from various different monomers can be used, but there are still considerable challenges in delamination when these copolymer binders are used in coatings.

[0010] Delamination of the composite is achieved by the disruption and / or breakage of the bonds between the polymer binder within the coating and the metal substrate at the coating-metal substrate interface. Therefore, to achieve high-speed, high recovery rate, high safety but with a lower usage of additional materials and low-cost delamination, an important goal is to more efficiently disrupt and / or break the bonds between the polymer binder within the coating and the metal substrate.

[0011] Methods have been attempted to achieve complete delamination of composites. Korean Patent Application Publication No. 20130099568A discloses a method for separating a composite comprising a polymer film coated on a metal surface by carbonizing the polymer using electromagnetic induction. First, a step of pre-treating the metal-polymer composite is carried out, wherein the polymer-metal composite is placed in an induction furnace so as to receive the maximum influence of the magnetic density per unit area during induction heating, making the movement of electrons on the metal surface more active. By induction heating, the metal-polymer composite is heated to 500-900 °C, which weakens the adhesion between the polymer and the metal surface and subsequently causes thermal decomposition and carbonization of the polymer coated on the metal surface, thus facilitating separation. This method can significantly save energy by adopting induction heating. However, the proposed method causes carbonization of the polymer, making it impossible to recycle the polymer. In addition, harmful or toxic pollutants may be generated during the polymer decomposition process.

[0012] In view of the above challenges, there is a continuing need to develop a unified and simple method to achieve efficient and complete delamination of composites at the coating-metal substrate interface, wherein the coating of the composite comprises a polymer binder and wherein the polymer binder is a copolymer. The method for composite delamination disclosed herein is to achieve effective disruption and / or breakage of the bond between the copolymer binder and the metal substrate in the composite coating. Therefore, a delamination method meeting these characteristics can be applied to composites containing a copolymer binder. This method can avoid complex separation processes and contamination of the metal substrate, achieve excellent material recovery rates, and allow delamination of the composite to be completed in a short time. Summary of the Invention

[0013] The above needs can be met by the various aspects and embodiments disclosed herein. In one aspect, there is provided a method for delaminating a composite by immersing the composite in a delamination solution, wherein the composite comprises a metal substrate and a coating applied to one or both sides of the metal substrate, and wherein the coating comprises a copolymer binder.

[0014] In some embodiments, the metal substrate is selected from the group consisting of stainless steel, titanium, nickel, aluminum, copper, platinum, gold, silver, chromium, zirconium, tungsten, molybdenum, tin, vanadium, zinc, cadmium, iron, cobalt, lead, and alloys thereof.

[0015] In some embodiments, the delamination solution comprises a delamination agent and an aqueous solvent.

[0016] In some embodiments, the delamination agent is a base. In some embodiments, the base is selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, calcium oxide, strontium oxide, barium oxide, and combinations thereof.

[0017] The delamination of the composite achieved by the method provided herein is very fast and simple, and does not cause adverse effects such as loss of coating material that cannot be recycled, damage to the coating material, or introduction of impurities in the metal substrate.

[0018] On the other hand, as one of the applications of the present invention, the above method can be used for delamination of battery electrodes, where the composite is the battery electrode, the metal substrate is the current collector, and the coating is the electrode layer. A method for delaminating a battery electrode by immersing the electrode in a stripping solution is provided herein, where the electrode comprises a current collector and an electrode layer coated on one or both sides of the current collector, and where the electrode layer comprises a copolymer binder.

[0019] In the present invention, simply using the stripping solution to delaminate the battery electrode at the electrode layer-current collector interface can significantly shorten the time required to achieve complete delamination, maximize the recovery of useful materials, eliminate the contamination of the current collector, and does not require subsequent processes. In addition, the method disclosed herein is found to be applicable to the delamination of both the cathode and the anode without causing corrosion problems to the current collector and / or the electrode active materials in the electrode layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A simplified view showing one embodiment of the composite.

[0021] Figure 2 A schematic diagram showing the coating-metal substrate interface structure in the proposed composite.

[0022] Figure 3 Is a flow chart of one embodiment, which shows the steps of delaminating the composite disclosed herein and subsequent further processing for extracting the composite components (i.e., the coating and the metal substrate) after delamination of the composite.

[0023] Figure 4 Shows the cathode layer and the current collector recovered after immersing the double-sided coated cathode in the stripping solution in Example 4, where the stripping solution comprises 1M sodium hydroxide and deionized water, and where the double-sided cathode comprises a copolymer binder.

[0024] Figure 5 Shows the recovered cathode of Comparative Example 1, where the stripping solution comprises 0.5M sodium hydroxide and deionized water, and where the double-sided coated cathode comprises polyvinylidene fluoride (PVDF) as the polymer binder. DETAILED DESCRIPTION

[0025] On the one hand, a method for delaminating a composite by immersing the composite in a stripping solution is provided herein, where the composite comprises a metal substrate and a coating applied on one or both sides of the metal substrate, and where the coating comprises a copolymer binder.

[0026] On the other hand, the present disclosure provides a method for stripping an electrode by immersing a lithium-ion battery electrode in a stripping solution, where the electrode includes a current collector and an electrode layer coated on one or both sides of the current collector, and the electrode layer includes a copolymer binder.

[0027] The term "electrode" refers to a "cathode" or an "anode".

[0028] The terms "positive electrode" and "cathode" are used interchangeably. Similarly, the terms "negative electrode" and "anode" are used interchangeably.

[0029] The term "binder" or "binder material" refers to a chemical compound, a mixture of compounds, or a polymer used to hold materials in place and adhere them to a conductive metal substrate to form a composite. In some embodiments, the binder refers to a chemical compound, a mixture of compounds, or a polymer used to hold an electrode material and / or a conductive agent in place and adhere them to a conductive metal component to form an electrode. In some embodiments, the electrode does not contain any conductive agent.

[0030] The term "conductive agent" refers to a material having good electrical conductivity. Thus, a conductive agent is typically mixed with an electrode active material when forming an electrode to improve the electrical conductivity of the electrode. In some embodiments, the conductive agent is chemically active. In some embodiments, the conductive agent is chemically inert.

[0031] The term "composite" refers to a metal substrate having a coating applied on one or both sides of the metal substrate, where the metal substrate and the coating may each include one or more layers. The term "constituent" in the context of a composite refers to the metal substrate and the coating.

[0032] The term "polymer" refers to a compound prepared by polymerizing the same or different types of monomers. The general term "polymer" includes the terms "homopolymer" and "copolymer".

[0033] The term "aqueous polymer" refers to a polymer that can be dispersed in an aqueous solvent (such as water) to form a solution or a colloidal system, where the polymer in the colloidal system does not easily self-aggregate.

[0034] The term "homopolymer" refers to a polymer prepared by polymerizing the same type of monomers.

[0035] The term "copolymer" refers to a polymer prepared by polymerizing two or more different types of monomers.

[0036] The term "polymer binder" refers to a binder having polymer properties. The term "copolymer binder" refers to a polymer binder, where the binder is specifically a copolymer.

[0037] As used herein, the term "unsaturated" refers to a moiety having one or more unsaturated units.

[0038] The term "alkyl" or "alkyl group" refers to a monovalent group having the general formula C n H 2n+1 derived by removing a hydrogen atom from a saturated, unbranched or branched aliphatic hydrocarbon, where n is an integer or an integer between 1 and 20 or an integer between 1 and 8. Examples of alkyl groups include, but are not limited to, (C1–C8) alkyl groups such as methyl, ethyl, propyl, isopropyl, 2-methyl-1-propyl, 2-methyl-2-propyl, 2-methyl-1-butyl, 3-methyl-1-butyl, 2-methyl-3-butyl, 2,2-dimethyl-1-propyl, 2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 2,2-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl and octyl. Longer alkyl groups include nonyl and decyl groups. The alkyl group can be unsubstituted or substituted with one or more suitable substituents. In addition, the alkyl group can be branched or unbranched. In some embodiments, the alkyl group contains at least 2, 3, 4, 5, 6, 7 or 8 carbon atoms.

[0039] The term "cycloalkyl" or "cycloalkyl group" refers to a saturated or unsaturated cyclic non-aromatic hydrocarbon group having a single ring or multiple fused rings. Examples of cycloalkyl groups include, but are not limited to, (C3-C7) cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl, as well as saturated cyclo-terpenes and saturated bicyclic terpenes, and (C3-C7) cycloalkenyl groups such as cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl and cycloheptenyl, as well as unsaturated cyclic terpenes and unsaturated bicyclic terpenes. The cycloalkyl group can be unsubstituted or substituted with one or two suitable substituents. In addition, the cycloalkyl group can be monocyclic or polycyclic. In some embodiments, the cycloalkyl group contains at least 5, 6, 7, 8, 9 or 10 carbon atoms.

[0040] The term "alkoxy" refers to an alkyl group as defined above, attached to the main carbon chain through an oxygen atom. Some non-limiting examples of alkoxy groups include methoxy, ethoxy, propoxy, butoxy, etc. And the alkoxy as defined above can be substituted or unsubstituted, where the substituents can be, but are not limited to, deuterium, hydroxyl, amino, halogen, cyano, alkoxy, alkyl, alkenyl, alkynyl, mercapto, nitro, etc.

[0041] The term "alkenyl" refers to an unsaturated straight-chain, branched-chain, or cyclic hydrocarbon group containing one or more carbon-carbon double bonds. Examples of alkenyl groups include, but are not limited to, vinyl, 1-propenyl, and 2-propenyl, which may optionally be substituted on one or more carbon atoms of the group.

[0042] The term "aryl" or "aryl group" refers to an organic group derived by removing one hydrogen atom from a monocyclic or polycyclic aromatic hydrocarbon. Non-limiting examples of aryl groups include phenyl, naphthyl, benzyl, tolanyl, sexiphenyl, phenanthrenyl, anthracenyl, coronenyl, and tolanylphenyl. The aryl group may be unsubstituted or substituted with one or more suitable substituents. In addition, the aryl group may be monocyclic or polycyclic. In some embodiments, the aryl group contains at least 6, 7, 8, 9, or 10 carbon atoms.

[0043] The term "aliphatic" refers to C1 to C 30 alkyl groups, C2 to C 30 alkenyl groups, C2 to C 30 alkynyl groups, C1 to C 30 alkylene groups, C2 to C 30 alkenylene groups, or C2 to C 30 alkynylene groups. In some embodiments, the alkyl group contains at least 2, 3, 4, 5, 6, 7, or 8 carbon atoms.

[0044] The term "aromatic" refers to a group containing an aromatic hydrocarbon ring, which optionally includes heteroatoms or substituents. Examples of such groups include, but are not limited to, phenyl, tolyl, biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, naphthyl, anthryl, phenanthryl, pyrenyl, triphenylenyl, and their derivatives.

[0045] The term "substituted" when used to describe a compound or chemical moiety means that at least one hydrogen atom of the compound or chemical moiety is replaced by another chemical moiety. Examples of substituents include, but are not limited to, halogen; alkyl; heteroalkyl; alkenyl; alkynyl; aryl; heteroaryl; hydroxy; alkoxy; amino; nitro; mercapto; thioether; imino; cyano; amido; phosphonato; phosphinato; carboxy; thiocarbonyl; sulfonyl; sulfonamide; acyl; formyl; acyloxy; alkoxycarbonyl; carbonyl; haloalkyl (e.g., trifluoromethyl); carbocyclic cycloalkyl which may be monocyclic or fused or unfused polycyclic (e.g., cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl) or heterocycloalkyl which may be monocyclic or fused or unfused polycyclic (e.g., pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl or thiazinyl); carbocyclic or heterocyclic, monocyclic or fused or unfused polycyclic aryl (e.g., phenyl, naphthyl, pyrrolyl, indolyl, furyl, thiophenyl, imidazolyl, oxazolyl, isoxazolyl, thiazolyl, triazolyl, tetrazolyl, pyrazolyl, pyridyl, quinolinyl, isoquinolinyl, acridinyl, pyrazinyl, pyridazinyl, pyrimidinyl, benzimidazolyl, benzothiophenyl or benzofuryl); amino (primary, secondary or tertiary); ortho-lower alkyl; ortho-aryl, aryl; aryl-lower alkyl; -CO2CH3; -CONH2; -OCH2CONH2; -NH2; -SO2NH2; -OCHF2; -CF3; -OCF3; -NH(alkyl); -N(alkyl)2; -NH(aryl); -N(alkyl)(aryl); -N(aryl)2; -CHO; -CO(alkyl); -CO(aryl); -CO2(alkyl); and -CO2(aryl); and these moieties may also optionally be substituted by a fused ring structure or a bridging structure (e.g., -OCH2O-). These substituents may optionally be further substituted by substituents selected from these groups. Unless otherwise specified, all chemical groups disclosed herein may be substituted.

[0046] The term "halogen" or "halo" means F, Cl, Br or I.

[0047] The term "monomer unit" means a constituent unit provided by a single monomer to the structure of a polymer.

[0048] The term "structural unit" means the total monomer units provided by the same monomer type in a polymer.

[0049] The term "acid salt group" means an acid salt formed when an acid reacts with a base. In some embodiments, the proton of the acid is replaced by a metal cation. In some embodiments, the proton of the acid is replaced by an ammonium ion.

[0050] The term "planetary mixer" refers to a device that can be used to mix or stir different materials to produce a homogeneous mixture, which consists of paddles that perform planetary motion within a container. In some embodiments, the planetary mixer includes at least one planetary paddle and at least one high-speed dispersing paddle. The planetary paddle and the high-speed dispersing paddle rotate on their respective axes and also continuously rotate around the container. The rotational speed can be expressed in units of revolutions per minute (rpm), which refers to the number of revolutions completed by a rotating body within one minute.

[0051] The term "ultrasonic generator" refers to a device capable of applying ultrasonic energy to agitate particles in a sample. Any ultrasonic generator that can disperse the slurries disclosed herein can be used herein. Some non-limiting examples of ultrasonic generators include ultrasonic baths, probe-type ultrasonic generators, and ultrasonic flow cells.

[0052] The term "ultrasonic bath" refers to a device in which ultrasonic energy is transmitted through the wall of the ultrasonic bath container to a liquid sample.

[0053] The term "probe-type ultrasonic generator" refers to an ultrasonic probe that is immersed in a medium for direct ultrasonic treatment. The term "direct ultrasonic treatment" refers to the direct coupling of ultrasonic waves into the treatment liquid.

[0054] The term "ultrasonic flow cell" or "ultrasonic reactor chamber" refers to a device in which ultrasonic treatment is performed in a flow mode. In some embodiments, the ultrasonic flow cell is in a single-channel, multi-channel, or recirculation configuration.

[0055] The term "apply" refers to the action of laying or spreading a substance on a surface.

[0056] The term "current collector" refers to any conductive layer that contacts an electrode layer and is capable of conducting current to the electrode during discharge or charging of a secondary battery. Some non-limiting examples of current collectors include a single conductive metal layer or substrate and a single conductive metal layer or substrate covered with a conductive coating (such as a carbon black-based coating). The conductive metal layer or substrate can be in the form of a foil or a porous body with a three-dimensional network structure. In some embodiments, the three-dimensional porous current collector is coated with a conformal carbon layer.

[0057] The term "electrode layer" refers to a coating containing an electrochemically active material that contacts a current collector. In some embodiments, the electrode layer is made by applying a coating on a current collector. In some embodiments, the electrode layer is located on one or both sides of the current collector. In other embodiments, the three-dimensional porous current collector is covered with a conformal electrode layer. Thus, an electrode is a composite in which the current collector is a metal substrate and the electrode layer is a coating.

[0058] The term "room temperature" refers to an indoor temperature of about 18°C to about 30°C, such as 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30°C. In some embodiments, room temperature refers to a temperature of about 20°C + / - 1°C or + / - 2°C or + / - 3°C. In other embodiments, room temperature refers to a temperature of about 22°C or about 25°C.

[0059] The term "solid content" refers to the amount of non-volatile substances remaining after evaporation.

[0060] The term "peel strength" refers to the magnitude of the force required to separate a current collector and an electrode active material coating that are adhered to each other. It is a measure of the adhesion strength between these two materials and is usually expressed in N / cm.

[0061] The term "adhesion strength" refers to the magnitude of the force required to separate a current collector and a polymer binder coating that are adhered to each other. It is a measure of the adhesion strength between these two materials and is usually expressed in N / cm.

[0062] The term "C rate" refers to the charging rate or discharging rate of a battery expressed in ampere-hours (Ah) or milliampere-hours (mAh) based on its total storage capacity. For example, a rate of 1C means using all the stored energy within one hour; 0.1C means using 10% of the energy within one hour or using all the energy within 10 hours; and 5C means using all the energy within 12 minutes.

[0063] The term "ampere-hour (Ah)" is the unit used to describe the storage capacity of a battery. For example, a battery with a capacity of 1Ah can provide a current of 1 ampere for 1 hour or a current of 0.5 ampere for 2 hours, etc. Thus, 1 ampere-hour (Ah) is equivalent to 3,600 coulombs of charge. Similarly, the term "milliampere-hour (mAh)" is also a unit used to describe the storage capacity of a battery and is 1 / 1,000 of an ampere-hour.

[0064] The term "battery cycle life" refers to the number of complete charge / discharge cycles that a battery can perform before its nominal capacity drops to less than 80% of its initial rated capacity.

[0065] The term "capacity" is a characteristic of an electrochemical cell and refers to the total amount of electric charge that an electrochemical cell (such as a battery) can hold. Capacity is usually expressed in units of ampere-hours. The term "specific capacity" refers to the capacity output per unit weight of an electrochemical cell (such as a battery) and is usually expressed in Ah / kg or mAh / g.

[0066] In the following description, all numerical values disclosed herein are approximate values, regardless of whether the terms "about" or "approximate" are used in combination. They can vary by 1%, 2%, 5%, or sometimes 10% to 20%. Whenever a numerical range with a lower limit R L and an upper limit R U is disclosed, any numerical value within that range has been specifically disclosed. Specifically, the following numerical values within that range are specifically disclosed: R = R L + k * (R U - R L ), where k is a variable from 0% to 100%. Also, any numerical range defined by two R values determined in the above manner is also specifically disclosed.

[0067] In this specification, all cases using the singular include cases using the plural, and vice versa.

[0068] As used herein, a "composite" refers to a metal substrate having a coating applied to one or both sides of the metal substrate, where the metal substrate and the coating may each comprise one or more layers, and where the coating comprises a polymeric binder. In some embodiments, the polymeric binder is a copolymer, i.e., a copolymer binder. Figure 1 Figure 100 shows a simplified view of the composite. The composite 100 includes a metal substrate 101 and a coating 102 applied to one side of the metal substrate 101. Applying a coating on the metal substrate, i.e., forming a composite, is one of the most commonly used techniques for changing the surface properties of the metal substrate to meet the performance requirements of various applications. Coatings are often used for various purposes, including protective effects (e.g., chemical resistance, corrosion resistance, scratch resistance, and wear resistance, etc.), adhesion effects, wettability modification effects, or biocompatibility effects.

[0069] The adhesion between the coating and the metal substrate within the composite is achieved through the interaction between the polymeric binder contained in the coating and the surface of the metal substrate on which the coating is applied. A copolymer binder compatible with an aqueous solvent (most commonly water) can firmly adhere the coating to the metal substrate. Therefore, such a copolymer binder is preferably used in the present invention. In addition, since these copolymer binders can achieve good dispersibility and stability in water, water-based coatings containing these copolymer binders will have good processing efficiency in terms of formation, storage, and utilization.

[0070] In some embodiments, the substrate is a metal substrate. In some embodiments, the substrate is selected from the group consisting of stainless steel, titanium, nickel, aluminum, copper, platinum, gold, silver, chromium, zirconium, tungsten, molybdenum, tin, vanadium, zinc, cadmium, iron, cobalt, lead, and their alloys.

[0071] Typically, before applying a coating on the surface of a metal substrate, the metal substrate is exposed to ambient air for a period of time. Ambient air mainly contains oxygen, water, and several organic and inorganic substances. When the metal substrate is exposed to the naturally occurring oxygen in the atmosphere, metal oxides inevitably form on the surface of the metal substrate. For example, metallic aluminum naturally has a strong reactivity with oxygen in the atmosphere, which can initiate the formation of aluminum oxide on the exposed aluminum surface. The aluminum oxide protects the underlying aluminum from further oxidation, so aluminum has good corrosion resistance. When the metal oxide on the surface of the metal substrate comes into contact with the moisture in the ambient air, the metal oxide undergoes hydroxylation, enriching the metal oxide surface with hydroxyl groups (-OH).

[0072] The hydroxyl groups on the surface of the metal substrate consist of an H atom covalently bonded to a more electronegative O atom and an electronegative O atom with a lone pair of electrons in the outermost electron shell. Within the hydroxyl group, the hydrogen atom is capable of forming a hydrogen bond with another molecule containing a highly electronegative atom (such as O, N, or F), and the oxygen atom is capable of accepting a hydrogen bond from the hydrogen atom of another molecule similarly bonded to a highly electronegative atom (such as O, N, or F).

[0073] Meanwhile, the metallic portion of the substrate still exists on the surface of the metal substrate in the form of a metal species (M δ+ ) with a partial positive charge, such as in the metal oxide formed on the surface of the metal substrate.

[0074] Figure 2 Schematic diagram showing the coating-metal substrate interface structure of the proposed composite represented by 200. Hydroxyl (-OH) groups, metal species (M δ+ ) with a partial positive charge, and oxygen (O) atoms of the metal oxide are all present on the surface of the metal substrate 201. The copolymer binder within the coating 202 and / or on the surface of the coating 202 contains structural units derived from monomers containing carboxylic acid groups. In this case, the structural units derived from monomers containing carboxylic acid groups contain carboxylate groups, where the carboxylate group is the salt of the carboxylic acid group.

[0075] The oxygen (O) and hydrogen (H) atoms present in the copolymer binder may interact via hydrogen bonding with the O and / or H atoms of the hydroxyl groups on the surface of the metal substrate and the O atoms in the metal oxide. In addition, anionic (COO - ) of the carboxylate groups contained in the copolymer binder undergoes ion-dipole interaction with the M δ+ species on the surface of the metal substrate. Therefore, hydrogen bonding and / or ion-dipole attraction are formed between the coating and the metal substrate, and these two types of interactions contribute significantly to the adhesion of the coating to the surface of the metal substrate.

[0076] The formulation of the copolymer binder disclosed herein is provided to provide extremely strong coating-metal substrate adhesion for various applications. However, when a product containing the composite reaches the end of its practicality or service life, or a defective product is produced during the production process, this strong adhesion poses additional challenges in the subsequent recycling steps when separating the coating from the metal substrate to which it is attached.

[0077] The peeling of the coating from the metal substrate in the composite is achieved by the disruption and / or breakage of the bonds between the copolymer binder in the coating and the surface of the metal substrate. Copolymers of different components exhibiting different specific properties require different methods to separate the coating from the metal substrate. Therefore, the method of the present invention is specifically developed to peel the composite by disrupting and / or breaking the bonds between the aqueous copolymer binder disclosed herein and the surface of the metal substrate.

[0078] The present invention provides a method for peeling a composite by immersing the composite in a stripping solution; wherein the composite comprises a metal substrate and a coating applied to one or both sides of the metal substrate, and the coating comprises a copolymer binder.

[0079] In some embodiments, the peeling of the composite occurs at the coating-metal substrate interface.

[0080] In some embodiments, the stripping solution comprises a stripping agent and an aqueous solvent. In some embodiments, the stripping agent is a water-soluble strong base. In some embodiments, the aqueous solvent consists only of water.

[0081] In the stripping solution, the strong base can be an oxide of an alkali metal or alkaline earth metal, a hydroxide of an alkali metal or alkaline earth metal, or a combination thereof. In the case of a hydroxide, the strong base dissociates in the aqueous solvent and releases the constituent ions in the strong base. In the case of an oxide, the oxide reacts with water and also forms ions.

[0082] These ions can enter the interface between the copolymer binder and the surface of the metal substrate. The ions disrupt the hydrogen bonds and ion-dipole interactions between the copolymer binder and the metal substrate. The aqueous solvent (such as water) present in the stripping solution also disrupts the ion-dipole interactions between the copolymer binder in the coating and the surface of the metal substrate. These aqueous solvent molecules further serve to solvate the copolymer, forming a solvent shell (a hydration shell in the case of water), which greatly reduces the strength of the electrostatic interactions between the copolymer binder in the coating and the metal substrate.

[0083] In some embodiments, some functional groups in the polymer that can dissociate in water, such as carboxylic acid groups, are not completely dissociated in water. A strong base will further neutralize the undissociated functional groups, thereby forming corresponding anions, such as carboxylate anions when carboxylic acid functional groups are present. The attraction of water to such anions (e.g., carboxylates) is stronger than the attraction of water to the undissociated functional groups. As these dissociable functional groups ionize, the solvation effect of the ionized functional groups in water will be stronger, thus more effectively weakening the interaction between the polymer and the metal substrate. This consequently leads to coating peeling.

[0084] Therefore, the method disclosed herein in the present invention aims to achieve the peeling of the composite by using a stripping solution to break and / or fracture the hydrogen bonds and / or ion-dipole interactions between the coating and the surface of the metal substrate, wherein the coating comprises a copolymer binder. This method is simple and does not require complex separation procedures. The proposed method ensures the complete peeling of the composite at the coating-metal substrate interface without contaminating the metal substrate, thus achieving excellent material recovery and enabling the efficient and rapid peeling of the composite.

[0085] Non-ionized copolymer functional groups do not interact with the surface of the metal substrate through ion-dipole interactions. Using only an aqueous solvent as the stripping solution may not be sufficient to completely peel the coating from the metal substrate because the solvation effect of the aqueous solvent on these non-ionized copolymer functional groups will be significantly lower; and the interactions (mainly hydrogen bonds) between these copolymer functional groups in the coating and the surface of the metal substrate are generally not disrupted and reduced to the extent that the composite can be completely peeled.

[0086] Therefore, both the stripping agent and the aqueous solvent should be used in combination as the stripping solution to achieve excellent composite peeling effects. In some embodiments, the stripping solution comprises a stripping agent and an aqueous solvent.

[0087] In some embodiments, the stripping agent is a strong base. In some embodiments, the stripping agent is a hydroxide of an alkali metal or an alkaline earth metal. In some embodiments, the stripping agent is an oxide of an alkali metal or an alkaline earth metal. In some embodiments, the stripping agent is lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, calcium oxide, strontium oxide, barium oxide, or a combination thereof.

[0088] In some embodiments, the aqueous solvent is a solution containing water as the main component and a volatile solvent (such as an alcohol, a lower aliphatic ketone, a lower alkyl acetate, etc.) as a minor component other than water. In some embodiments, the proportion of water in the aqueous solvent is about 51% to about 100%, about 51% to about 95%, about 51% to about 90%, about 51% to about 85%, about 51% to about 80%, about 51% to about 75%, about 51% to about 70%, about 55% to about 100%, about 55% to about 95%, about 55% to about 90%, about 55% to about 85%, about 55% to about 80%, about 60% to about 100%, about 60% to about 95%, about 60% to about 90%, about 60% to about 85%, about 60% to about 80%, about 65% to about 100%, about 65% to about 95%, about 65% to about 90%, about 65% to about 85%, about 70% to about 100%, about 70% to about 95%, about 70% to about 90%, about 70% to about 85%, about 75% to about 100%, about 75% to about 95%, or about 80% to about 100% by weight.

[0089] In some embodiments, the proportion of water in the aqueous solvent is more than 50%, more than 55%, more than 60%, more than 65%, more than 70%, more than 75%, more than 80%, more than 85%, more than 90%, or more than 95% by weight. In some embodiments, the proportion of water in the aqueous solvent is less than 55%, less than 60%, less than 65%, less than 70%, less than 75%, less than 80%, less than 85%, less than 90%, or less than 95% by weight. In some embodiments, the aqueous solvent consists only of water, that is, the proportion of water in the aqueous solvent is 100% by weight.

[0090] Some non-limiting examples of water include tap water, bottled water, purified water, pure water, distilled water, deionized water, D2O, and combinations thereof. In some embodiments, the aqueous solvent is deionized water. Water can be part of the stripping solution to form a solvent shell around the copolymer binder of the coating and on the metal substrate surface at the coating-metal substrate surface interface. This helps to break the interaction between the copolymer binder in the coating and the metal substrate surface, resulting in complete stripping of the composite.

[0091] Any water-miscible solvent or volatile solvent can be used as the minor component of the aqueous solvent (i.e., the solvent other than water). Some non-limiting examples of water-miscible solvents or volatile solvents include alcohols, lower aliphatic ketones, lower alkyl acetates, and combinations thereof. The addition of an alcohol can improve the solubility of the stripper and lower the freezing point of water. Some non-limiting examples of alcohols include C1-C4 alcohols, such as methanol, ethanol, isopropanol, n-propanol, tert-butanol, n-butanol, and combinations thereof. Some non-limiting examples of lower aliphatic ketones include acetone, dimethyl ketone, methyl ethyl ketone (MEK), and combinations thereof. Some non-limiting examples of lower alkyl acetates include ethyl acetate (EA), isopropyl acetate, propyl acetate, butyl acetate (BA), and combinations thereof. In some embodiments, the aqueous solvent does not contain an alcohol, a lower aliphatic ketone, a lower alkyl acetate, or a combination thereof.

[0092] Surfactants are used as additives to the stripping solution to improve the stripping rate. However, adding a surfactant to the stripping solution will become an impurity in the resulting solution, leading to a decrease in product purity or requiring time and funds for developing a separation system to remove the surfactant. In addition, surfactants are harmful to the environment after discharge, and some surfactants may also pose a hazard to health. Therefore, in some embodiments, no surfactant is added to the stripping solution. In some embodiments, the stripping solution does not contain cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants.

[0093] In some embodiments, no anionic surfactants including fatty acid salts; alkyl sulfates; polyoxyalkylene alkyl ether acetates; alkylbenzene sulfonates; polyoxyalkylene alkyl ether sulfates; higher fatty acid amide sulfonates; N-acylsarcosin salts; alkyl phosphates; polyoxyalkylene alkyl ether phosphates; long-chain sulfosuccinates; long-chain N-acylglutamates; polymers and copolymers containing acrylic acid, acid anhydrides, esters, vinyl monomers, and / or olefins and their alkali metal salts, alkaline earth metal salts, and / or ammonium salt derivatives; polycarboxylates; formalin condensates of naphthalenesulfonic acid; alkylnaphthalenesulfonic acid; naphthalenesulfonic acid; alkylnaphthalenesulfonates; formalin condensates of acids and naphthalenesulfonates (such as their alkali metal salts, alkaline earth metal salts, ammonium salts, or amine salts); melamine sulfonic acid; alkylmelamine sulfonic acid; formalin condensates of melamine sulfonic acid; formalin condensates of alkylmelamine sulfonic acid; alkali metal salts, alkaline earth metal salts, ammonium salts, and amine salts of melamine sulfonic acid; lignosulfonic acid; and alkali metal salts, alkaline earth metal salts, ammonium salts, and amine salts of lignosulfonic acid are added to the stripping solution.

[0094] In some embodiments, no cationic surfactants including alkyltrimethylammonium salts such as stearyltrimethylammonium chloride, dodecyltrimethylammonium chloride, and cetyltrimethylammonium bromide; dialkyldimethylammonium salts; trialkylmethylammonium salts; tetraalkylammonium salts; alkylamine salts; benzalkonium salts; alkylpyridinium salts; and imidazolium salts are added to the stripping solution.

[0095] In some embodiments, no nonionic surfactants including alkyl ethers with polyalkylene oxides added, polyalkylene styrene phenyl ethers, polyols, ester compounds of monovalent fatty acids, polyalkylene alkyl phenyl ethers, polyalkylene fatty acid ethers, polyalkylene sorbitan fatty acid esters, glycerol fatty acid esters, polyalkylene castor oils, polyalkylene hydrogenated castor oils, polyalkylene sorbitol fatty acid esters, polyglycerol fatty acid esters, alkyl glycerol ethers, polyalkylene cholesterol ethers, alkyl glycosides, sucrose fatty acid esters, polyalkylene alkyl amines, polyoxyethylene - polyoxypropylene block polymers, sorbitan fatty acid esters, and fatty acid alkanolamides are added to the stripping solution.

[0096] In some embodiments, no zwitterionic surfactants including sodium 2 - undecyl - N,N - (hydroxyethyl carboxymethyl) - 2 - imidazoline, disodium 2 - coco - 2 - imidazoline hydroxide - 1 - carboxyethyloxy; imidazoline - based amphoteric surfactants; 2 - heptadecyl - N - carboxymethyl - N - hydroxyethyl imidazoline betaine, lauryldimethylaminoacetic acid betaine, alkyl betaines, amide betaines, sulfobetaines, and other betaine - based amphoteric surfactants; N - lauryl glycine, N - lauryl β - alanine, N - stearyl β - alanine, lauryldimethylamine oxide, oleyl dimethylamine oxide, sodium lauryl glutamate, lauryldimethylaminoacetic acid betaine, stearyldimethylaminoacetic acid betaine, coconut amide propyl hydroxysulfobetaine, and 2 - alkyl - N - carboxymethyl - N - hydroxyethyl imidazoline betaine are added to the stripping solution.

[0097] In some embodiments, the composite includes a metal substrate and coatings applied on one or both sides of the metal substrate.

[0098] In some embodiments, the coating includes a polymer binder. The purpose of the polymer binder in the coating is to provide an adhesive effect between the coating and the metal substrate within the composite. In some embodiments, the polymer binder includes an aqueous copolymer.

[0099] In some embodiments, the copolymer comprises structural unit (a), wherein structural unit (a) is derived from a monomer selected from the group consisting of monomers containing a carboxylic acid group, monomers containing a carboxylate group, monomers containing a sulfonic acid group, monomers containing a sulfonate group, monomers containing a phosphonic acid group, monomers containing a phosphonate group, and combinations thereof. In some embodiments, the salt group is a salt of an acid group. In some embodiments, the monomer containing a salt group contains an alkali metal cation. Examples of the alkali metal forming the alkali metal cation include lithium, sodium, and potassium. In some embodiments, the monomer containing a salt group contains an ammonium cation. In some embodiments, structural unit (a) may comprise a combination of a monomer containing a salt group and a monomer containing an acid group.

[0100] In some embodiments, the monomer containing a carboxylic acid group is acrylic acid, methacrylic acid, crotonic acid, 2-butylcrotonic acid, cinnamic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, 4,4-dimethylitaconic acid (tetraconic acid), or a combination thereof. In certain embodiments, the monomer containing a carboxylic acid group is 2-ethylacrylic acid, isocrotonic acid, cis-2-pentenoic acid, trans-2-pentenoic acid, angelic acid, tiglic acid, 3,3-dimethylacrylic acid, 3-propylacrylic acid, trans-2-methyl-3-ethylacrylic acid, cis-2-methyl-3-ethylacrylic acid, 3-isopropylacrylic acid, trans-3-methyl-3-ethylacrylic acid, cis-3-methyl-3-ethylacrylic acid, 2-isopropylacrylic acid, trimethylacrylic acid, 2-methyl-3,3-diethylacrylic acid, 3-butylacrylic acid, 2-butylacrylic acid, 2-pentylacrylic acid, 2-methyl-2-hexenoic acid, trans-3-methyl-2-hexenoic acid, 3-methyl-3-propylacrylic acid, 2-ethyl-3-propylacrylic acid, 2,3-diethylacrylic acid, 3,3-diethylacrylic acid, 3-methyl-3-hexylacrylic acid, 3-methyl-3-tert-butylacrylic acid, 2-methyl-3-pentylacrylic acid, 3-methyl-3-pentylacrylic acid, 4-methyl-2-hexenoic acid, 4-ethyl-2-hexenoic acid, 3-methyl-2-ethyl-2-hexenoic acid, 3-tert-butylacrylic acid, 2,3-dimethyl-3-ethylacrylic acid, 3,3-dimethyl-2-ethylacrylic acid, 3-methyl-3-isopropylacrylic acid, 2-methyl-3-isopropylacrylic acid, trans-2-octenoic acid, cis-2-octenoic acid, trans-2-decenoic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, or a combination thereof. In some embodiments, the monomer containing a carboxylic acid group is methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, bromomaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, difluoromaleic acid, nonyl hydrogenmaleate, decyl hydrogen maleate, dodecyl hydrogen maleate, octadecyl hydrogen maleate, fluoroalkyl hydrogen maleate, or a combination thereof. In some embodiments, the monomer containing a carboxylic acid group is maleic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, acrylic anhydride, methacrylic anhydride, methacrolein, methacryloyl chloride, methacryloyl fluoride, methacryloyl bromide, or a combination thereof.

[0101] In some embodiments, the monomer containing a carboxylate group is acrylate, methacrylate, crotonate, 2-butylcrotonate, cinnamate, maleate, maleic anhydride salt, fumarate, itaconate, itaconic anhydride salt, 4,4-dimethylitaconate or a combination thereof. In certain embodiments, the monomer containing a carboxylate group is 2-ethylacrylate, isocrotonate, cis-2-pentenoate, trans-2-pentenoate, angelate, tiglate, 3,3-dimethylacrylate, 3-propylacrylate, trans-2-methyl-3-ethylacrylate, cis-2-methyl-3-ethylacrylate, 3-isopropylacrylate, trans-3-methyl-3-ethylacrylate, cis-3-methyl-3-ethylacrylate, 2-isopropylacrylate, trimethylacrylate, 2-methyl-3,3-diethylacrylate, 3-butylacrylate, 2-butylacrylate, 2-pentylacrylate, 2-methyl-2-hexenoate, trans-3-methyl-2-hexenoate, 3-methyl-3-propylacrylate, 2-ethyl-3-propylacrylate, 2,3-diethylacrylate, 3,3-diethylacrylate, 3-methyl-3-hexylacrylate, 3-methyl-3-tert-butylacrylate, 2-methyl-3-pentylacrylate, 3-methyl-3-pentylacrylate, 4-methyl-2-hexenoate, 4-ethyl-2-hexenoate, 3-methyl-2-ethyl-2-hexenoate, 3-tert-butylacrylate, 2,3-dimethyl-3-ethylacrylate, 3,3-dimethyl-2-ethylacrylate, 3-methyl-3-isopropylacrylate, 2-methyl-3-isopropylacrylate, trans-2-octenoate, cis-2-octenoate, trans-2-decenoate, α-acetoxyacrylate, β-trans-aryloxyacrylate, α-chloro-β-E-methoxyacrylate or a combination thereof. In some embodiments, the monomer containing a carboxylate group is methylmaleate, dimethylmaleate, phenylmaleate, bromomaleate, chloromaleate, dichloromaleate, fluoromaleate, difluoromaleate or a combination thereof.

[0102] In some embodiments, the monomer containing a sulfonic acid group is vinylsulfonic acid, methylvinylsulfonic acid, allylvinylsulfonic acid, allylsulfonic acid, methylallylsulfonic acid, styrenesulfonic acid, 2-sulfoethyl methacrylate, 2-methyl-2-propene-1-sulfonic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid, 3-allyloxy-2-hydroxy-1-propanesulfonic acid, allyl hydrogen sulfate, vinyl hydrogen sulfate or a combination thereof.

[0103] In some embodiments, the monomers containing sulfonate groups are vinyl sulfonate, methyl vinyl sulfonate, allyl vinyl sulfonate, allyl sulfonate, methyl allyl sulfonate, styrene sulfonate, 2-sulfoethyl methacrylate, 2-methyl-2-propene-1-sulfonate, 2-acrylamido-2-methyl-1-propane sulfonate, 3-allyloxy-2-hydroxy-1-propane sulfonate, allyl sulfate, vinyl sulfate, or a combination thereof.

[0104] In some embodiments, the monomers containing phosphonic acid groups are vinyl phosphonic acid, allyl phosphonic acid, vinylbenzyl phosphonic acid, acrylamide alkyl phosphonic acid, methacrylamide alkyl phosphonic acid, acrylamide alkyl diphosphonic acid, acrylyl phosphonic acid, 2-methacryloyloxyethyl phosphonic acid, bis(2-methacryloyloxyethyl) phosphonic acid, ethylene 2-methacryloyloxyethyl phosphonic acid, ethyl-2-methacryloyloxyethyl phosphonic acid, allyl hydrogen phosphate, vinyl hydrogen phosphate, or a combination thereof.

[0105] In some embodiments, the monomers containing phosphonate groups are vinyl phosphonate, allyl phosphonate, vinylbenzyl phosphonate, acrylamide alkyl phosphonate, methacrylamide alkyl phosphonate, acrylamide alkyl diphosphonate, acrylyl phosphonate, 2-methacryloyloxyethyl phosphonate, bis(2-methacryloyloxyethyl) phosphonate, ethylene 2-methacryloyloxyethyl phosphonate, ethyl-2-methacryloyloxyethyl phosphonate, allyl phosphate, vinyl phosphate, or a combination thereof.

[0106] In some embodiments, based on the total molar number of monomer units in the copolymer binder, the proportion of structural unit (a) in the copolymer is about 15% to about 30%, about 16% to about 30%, about 17% to about 30%, about 18% to about 30%, about 19% to about 30%, about 20% to about 30%, about 21% to about 30%, about 22% to about 30%, about 23% to about 30%, about 24% to about 30%, about 25% to about 30%, about 15% to about 27%, about 16% to about 27%, about 17% to about 27%, about 18% to about 27%, about 19% to about 27%, about 20% to about 27%, about 21% to about 27%, about 22% to about 27%, about 15% to about 25%, about 16% to about 25%, about 17% to about 25%, about 18% to about 25%, about 19% to about 25%, or about 20% to about 25% by mole.

[0107] In some embodiments, based on the total molar number of monomer units in the copolymer binder, the proportion of structural unit (a) in the copolymer is less than 30%, less than 29%, less than 28%, less than 27%, less than 26%, less than 25%, less than 24%, less than 23%, less than 22%, less than 21% or less than 20% by mole. In some embodiments, based on the total molar number of monomer units in the copolymer binder, the proportion of structural unit (a) in the copolymer is more than 15%, more than 16%, more than 17%, more than 18%, more than 19%, more than 20%, more than 21%, more than 22%, more than 23%, more than 24% or more than 25% by mole.

[0108] In some embodiments, the copolymer further comprises structural unit (b), which is derived from a monomer selected from the group consisting of monomers containing an amide group, monomers containing a hydroxyl group, and combinations thereof.

[0109] In some embodiments, the monomer containing an amide group is acrylamide, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-n-propylmethacrylamide, N-isopropylmethacrylamide, isopropylacrylamide, N-n-butylmethacrylamide, N-isobutylmethacrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N-hydroxymethylmethacrylamide, N-(methoxymethyl)methacrylamide, N-(ethoxymethyl)methacrylamide, N-(propoxymethyl)methacrylamide, N-(butoxymethyl)methacrylamide, N,N-dimethylmethacrylamide, N-(3-(dimethylamino)propyl)methacrylamide, N-(2-(dimethylamino)ethyl)methacrylamide, N,N-(dihydroxymethyl)methacrylamide, diacetonemethacrylamide, diacetoneacrylamide, methacryloylmorpholine, N-hydroxymethacrylamide, N-methoxymethacrylamide, N-methoxymethylmethacrylamide, N,N'-methylenebisacrylamide (MBA), N-hydroxymethylacrylamide, or combinations thereof.

[0110] In some embodiments, the monomer containing a hydroxyl group contains a hydroxyl group and an alkyl group having C1 to C 20 or a C5 to C 20Methacrylates of cycloalkyl groups. In some embodiments, the monomer containing a hydroxyl group is 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl acrylate, 6-hydroxyhexyl methacrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol mono(meth)acrylate, allyl alcohol, or a combination thereof.

[0111] In some embodiments, based on the total molar number of monomer units in the copolymer binder, the proportion of structural unit (b) in the copolymer is about 5% to about 20%, about 6% to about 20%, about 7% to about 20%, about 8% to about 20%, about 9% to about 20%, about 10% to about 20%, about 11% to about 20%, about 12% to about 20%, about 13% to about 20%, about 14% to about 20%, about 15% to about 20%, about 5% to about 17%, about 6% to about 17%, about 7% to about 17%, about 8% to about 17%, about 9% to about 17%, about 10% to about 17%, about 11% to about 17%, about 12% to about 17%, about 5% to about 15%, about 6% to about 15%, about 7% to about 15%, about 8% to about 15%, about 9% to about 15%, or about 10% to about 15% by mole.

[0112] In some embodiments, based on the total molar number of monomer units in the copolymer binder, the proportion of structural unit (b) in the copolymer is less than 20%, less than 19%, less than 18%, less than 17%, less than 16%, less than 15%, less than 14%, less than 13%, less than 12%, less than 11%, or less than 10% by mole. In some embodiments, based on the total molar number of monomer units in the copolymer binder, the proportion of structural unit (b) in the copolymer is more than 5%, more than 6%, more than 7%, more than 8%, more than 9%, more than 10%, more than 11%, more than 12%, more than 13%, more than 14%, or more than 15% by mole.

[0113] In some embodiments, the copolymer further comprises a structural unit (c) derived from a monomer selected from the group consisting of monomers containing a nitrile group, monomers containing an ester group, monomers containing an epoxy group, fluorine-containing monomers, and combinations thereof.

[0114] In some embodiments, the monomer containing a nitrile group includes an α,β-ethylenically unsaturated nitrile monomer. In some embodiments, the monomer containing a nitrile group is acrylonitrile, α-halopropionitrile, α-alkylacrylonitrile, or a combination thereof. In some embodiments, the monomer containing a nitrile group is α-chloropropionitrile, α-bromopropionitrile, α-fluoropropionitrile, methacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-n-hexylacrylonitrile, α-methoxyacrylonitrile, 3-methoxyacrylonitrile, 3-ethoxyacrylonitrile, α-acetoxyacrylonitrile, α-phenylacrylonitrile, α-tolylacrylonitrile, α-(methoxyphenyl)acrylonitrile, α-(chlorophenyl)acrylonitrile, α-(cyanophenyl)acrylonitrile, vinylidenecyanide, or a combination thereof.

[0115] In some embodiments, the monomer containing an ester group is a C1-C 20 alkyl acrylate, a C1-C 20 alkyl (meth)acrylate, a cycloalkyl acrylate, or a combination thereof. In some embodiments, the monomer containing an ester group is methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, amyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 3,3,5-trimethylhexyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate, cyclohexyl acrylate, phenyl acrylate, methoxymethyl acrylate, methoxyethyl acrylate, ethoxymethyl acrylate, ethoxyethyl acrylate, perfluorooctyl acrylate, stearyl acrylate, or a combination thereof. In some embodiments, the monomer containing an ester group is cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, or a combination thereof. In some embodiments, the monomer containing an ester group is methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, stearyl methacrylate, 2,2,2-trifluoroethyl methacrylate, phenyl methacrylate, benzyl methacrylate, or a combination thereof.

[0116] In some embodiments, the epoxy group-containing monomer is vinyl glycidyl ether, allyl glycidyl ether, allyl 2,3-epoxypropyl ether, butenyl glycidyl ether, butadiene monoepoxide, chloroprene monoepoxide, 3,4-epoxy-1-butene, 4,5-epoxy-2-pentene, 3,4-epoxy-1-vinylcyclohexane, 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexyl ethylene, epoxy-4-vinylcyclohexene, 1,2-epoxy-5,9-cyclododecadiene, or a combination thereof.

[0117] In some embodiments, the epoxy group-containing monomer is 3,4-epoxy-1-butene, 1,2-epoxy-5-hexene, 1,2-epoxy-9-decene, glycidyl acrylate, glycidyl methacrylate, glycidyl crotonate, glycidyl 2,4-dimethylpentenoate, glycidyl 4-hexenoate, glycidyl 4-heptenoate, glycidyl 5-methyl-4-heptenoate, glycidyl sorbate, glycidyl linoleate, glycidyl oleate, glycidyl 3-butenoate, glycidyl 3-pentenoate, glycidyl 4-methyl-3-pentenoate, or a combination thereof.

[0118] In some embodiments, the fluorine-containing monomer is an acrylate, methacrylate, or a combination thereof containing a C1-C 20 alkyl group, wherein the monomer contains at least one fluorine atom. In some embodiments, the fluorine-containing monomer is a perfluoroalkyl acrylate, such as perfluorododecyl acrylate, perfluorooctyl acrylate, perfluorobutyl acrylate, perfluorohexylethyl acrylate, and perfluorooctylethyl acrylate; perfluoroalkyl methacrylate, such as perfluorododecyl methacrylate, perfluorooctyl methacrylate, perfluorobutyl methacrylate, perfluorohexylethyl methacrylate, and perfluorooctylethyl methacrylate; perfluorooxyalkyl acrylate, such as perfluorododecyloxyethyl acrylate and perfluorodecyloxyethyl acrylate; perfluorooxyalkyl methacrylate, such as perfluorododecyloxyethyl methacrylate and perfluorodecyloxyethyl methacrylate, or a combination thereof. In some embodiments, the fluorine-containing monomer is a carboxylate salt containing at least one C1-C 20 alkyl group and at least one fluorine atom, wherein the carboxylate salt is selected from the group consisting of crotonate, malate, fumarate, itaconate, or a combination thereof. In some embodiments, the fluorine-containing monomer is vinyl fluoride, trifluoroethylene, trifluorochloroethylene, fluoroalkyl vinyl ether, perfluoroalkyl vinyl ether, hexafluoropropene, 2,3,3,3-tetrafluoropropene, vinylidene fluoride, tetrafluoroethylene, 2-fluoroacrylate, or a combination thereof.

[0119] In some embodiments, based on the total molar number of monomer units in the copolymer binder, the proportion of structural unit (c) in the copolymer is about 50% to about 75%, about 51% to about 75%, about 52% to about 75%, about 53% to about 75%, about 54% to about 75%, about 55% to about 75%, about 56% to about 75%, about 57% to about 75%, about 58% to about 75%, about 59% to about 75%, about 60% to about 75%, about 61% to about 75%, about 62% to about 75%, about 63% to about 75%, about 64% to about 75%, about 65% to about 75%, about 50% to about 70%, about 51% to about 70%, about 52% to about 70%, about 53% to about 70%, about 54% to about 70%, about 55% to about 70%, about 56% to about 70%, about 57% to about 70%, about 58% to about 70%, about 59% to about 70%, about 60% to about 70%, about 61% to about 70%, about 62% to about 70%, about 63% to about 70%, about 64% to about 70%, about 65% to about 70%, about 55% to about 65%, about 56% to about 65%, about 57% to about 65%, about 58% to about 65%, about 59% to about 65%, or about 60% to about 65% by mole.

[0120] In some embodiments, based on the total molar number of monomer units in the copolymer binder, the proportion of structural unit (c) in the copolymer is less than 75%, less than 74%, less than 73%, less than 72%, less than 71%, less than 70%, less than 69%, less than 68%, less than 67%, less than 66%, less than 65%, less than 64%, less than 63%, less than 62%, less than 61%, less than 60%, less than 59%, less than 58%, less than 57%, less than 56%, or less than 55% by mole. In some embodiments, based on the total molar number of monomer units in the copolymer binder, the proportion of structural unit (c) in the copolymer is more than 50%, more than 51%, more than 52%, more than 53%, more than 54%, more than 55%, more than 56%, more than 57%, more than 58%, more than 59%, more than 60%, more than 61%, more than 62%, more than 63%, more than 64%, more than 65%, more than 66%, more than 67%, more than 68%, more than 69%, or more than 70% by mole.

[0121] In other embodiments, the copolymer further comprises a structural unit derived from an olefin. Any hydrocarbon containing at least one carbon-carbon double bond can be used as the olefin without any particular limitation. In some embodiments, the olefin includes C2-C 20 aliphatic compounds, C8-C 20 aromatic compounds or cyclic compounds containing vinyl unsaturation, C4-C 40Diolefins and combinations thereof. In some embodiments, the olefin is styrene, ethylene, propylene, isobutene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, cyclobutene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4,6-dimethyl-1-heptene, 4-vinylcyclohexene, vinylcyclohexane, norbornene, norbornadiene, ethylidene norbornene, cyclopentene, cyclohexene, dicyclopentadiene, cyclooctene, or a combination thereof. In some embodiments, the copolymer does not contain structural units derived from olefins. In some embodiments, the copolymer does not contain structural units derived from styrene, ethylene, propylene, isobutene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, cyclobutene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4,6-dimethyl-1-heptene, 4-vinylcyclohexene, vinylcyclohexane, norbornene, norbornadiene, ethylidene norbornene, cyclopentene, cyclohexene, dicyclopentadiene, or cyclooctene.

[0122] Monomers containing a conjugated diene group belong to olefins. In some embodiments, the monomers containing a conjugated diene group include C4-C 40 Diolefins; aliphatic conjugated diene monomers such as 1,3-butadiene, 1,3-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,7-octadiene, 1,9-decadiene, isoprene, myrcene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene; substituted linear conjugated pentadienes, substituted side-chain conjugated hexadienes, and combinations thereof. In some embodiments, the copolymer does not contain structural units derived from C4-C 40 Diolefins; aliphatic conjugated diene monomers such as 1,3-butadiene, 1,3-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,7-octadiene, 1,9-decadiene, isoprene, myrcene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene; substituted linear conjugated pentadienes or substituted side-chain conjugated hexadienes.

[0123] In other embodiments, the copolymer further comprises structural units derived from monomers containing aromatic vinyl groups. In some embodiments, the monomers containing aromatic vinyl groups are styrene, α-methylstyrene, vinyltoluene, divinylbenzene, or combinations thereof. In some embodiments, the copolymer does not contain structural units derived from monomers containing aromatic vinyl groups. In some embodiments, the copolymer does not contain structural units derived from styrene, α-methylstyrene, vinyltoluene, or divinylbenzene.

[0124] In some embodiments, the metal substrate may be in the form of a foil, sheet, or film. In some embodiments, the metal substrate is selected from the group consisting of stainless steel, titanium, nickel, aluminum, copper, platinum, gold, silver, chromium, zirconium, tungsten, molybdenum, tin, vanadium, zinc, cadmium, iron, cobalt, lead, and alloys thereof. In some embodiments, the metal substrate may comprise two or more layers, wherein the material of each layer is selected from the group consisting of stainless steel, titanium, nickel, aluminum, copper, platinum, gold, silver, chromium, zirconium, tungsten, molybdenum, tin, vanadium, zinc, cadmium, iron, cobalt, lead, and alloys thereof. In some embodiments, the metal substrate has a bilayer structure. In some embodiments, the metal substrate has three or more layers. In some embodiments, the metal substrate has only one layer. In some embodiments, the material of each layer in the metal substrate is the same. In some embodiments, the material of each layer in the metal substrate is different or partially different.

[0125] In some embodiments, when the metal substrate comprises more than one layer, the metal substrate comprises a layer of insulating material. In some embodiments, the insulating material is a polymeric material selected from the group consisting of polycarbonate, polyacrylate, polyacrylonitrile, polyester, polyamide, polystyrene, polyurethane, polyepoxy resin, poly(acrylonitrile butadiene styrene), polyimide, polyolefin, polyethylene, polypropylene, polyphenylene sulfide, poly(vinyl ester), polyvinyl chloride, polyether, polyphenylene ether, cellulose polymer, and combinations thereof. When the metal substrate comprises a layer of insulating material, the coating is applied to the metal layer on the outside of the substrate.

[0126] In some embodiments, the metal substrate is coated with a layer of carbon-containing material. This layer of carbon-containing material will be part of the coating. In some embodiments, the metal substrate is not coated with a layer of carbon-containing material.

[0127] When the time for immersing the composite in the stripping solution is insufficient, the stripping agent and the aqueous solvent contained in the stripping solution may not have enough time to shake, interfere with, and break the bonds initially formed between the coating and the metal substrate surface to the extent that the composite can be completely stripped. However, when the composite is immersed in the stripping solution for a long time, the metal substrate may be corroded due to the prolonged contact time between the composite and the stripping agent (such as strong alkali) contained in the stripping solution. The time for stripping is not particularly limited, but the time used should be long enough for complete stripping to occur, but short enough to ensure that the corrosion of the metal substrate does not occur.

[0128] In some embodiments, the time for immersing the composite in the stripping solution is from about 1 second to about 120 minutes, from about 5 seconds to about 120 minutes, from about 10 seconds to about 120 minutes, from about 20 seconds to about 120 minutes, from about 30 seconds to about 120 minutes, from about 45 seconds to about 120 minutes, from about 60 seconds to about 120 minutes, from about 75 seconds to about 120 minutes, from about 90 seconds to about 120 minutes, from about 105 seconds to about 120 minutes, from about 120 seconds to about 120 minutes, from about 30 seconds to about 90 minutes, from about 30 seconds to about 75 minutes, from about 30 seconds to about 60 minutes, from about 30 seconds to about 45 minutes, from about 30 seconds to about 30 minutes, from about 30 seconds to about 20 minutes, from about 30 seconds to about 10 minutes, from about 30 seconds to about 5 minutes, from about 60 seconds to about 90 minutes, from about 60 seconds to about 75 minutes, from about 60 seconds to about 60 minutes, from about 60 seconds to about 45 minutes, from about 60 seconds to about 30 minutes, from about 60 seconds to about 20 minutes, from about 60 seconds to about 10 minutes, from about 60 seconds to about 5 minutes, from about 120 seconds to about 60 minutes, from about 120 seconds to about 45 minutes, from about 120 seconds to about 30 minutes, from about 120 seconds to about 20 minutes, from about 120 seconds to about 10 minutes, or from about 120 seconds to about 5 minutes.

[0129] In some embodiments, the time for immersing the composite in the stripping solution is less than 120 minutes, less than 105 minutes, less than 90 minutes, less than 75 minutes, less than 60 minutes, less than 45 minutes, less than 30 minutes, less than 20 minutes, less than 10 minutes, less than 5 minutes, less than 1 minute, less than 45 seconds, less than 30 seconds, less than 20 seconds, or less than 10 seconds. In some embodiments, the time for immersing the composite in the stripping solution is more than 1 second, more than 5 seconds, more than 10 seconds, more than 20 seconds, more than 30 seconds, more than 45 seconds, more than 60 seconds, more than 75 seconds, more than 90 seconds, more than 105 seconds, more than 120 seconds, more than 5 minutes, more than 10 minutes, more than 20 minutes, or more than 30 minutes.

[0130] The stripping temperature is not particularly limited, but the temperature should not be too low such that it takes a long time to achieve complete stripping, nor should the temperature be too high such that it poses health and safety risks.

[0131] In some embodiments, the temperature at which the composite is immersed in the stripping solution is about 10°C to about 90°C, about 15°C to about 90°C, about 20°C to about 90°C, about 25°C to about 90°C, about 30°C to about 90°C, about 35°C to about 90°C, about 40°C to about 90°C, about 45°C to about 90°C, about 50°C to about 90°C, about 55°C to about 90°C, about 60°C to about 90°C, about 65°C to about 90°C, about 70°C to about 90°C, about 75°C to about 90°C, about 20°C to about 75°C, about 25°C to about 75°C, about 30°C to about 75°C, about 35°C to about 75°C, about 40°C to about 75°C, about 45°C to about 75°C, about 50°C to about 75°C, about 55°C to about 75°C, about 60°C to about 75°C, about 25°C to about 60°C, about 30°C to about 60°C, about 35°C to about 60°C, about 40°C to about 60°C or about 45°C to about 60°C.

[0132] In some embodiments, the temperature at which the composite is immersed in the stripping solution is below 90°C, below 85°C, below 80°C, below 75°C, below 70°C, below 65°C, below 60°C, below 55°C, below 50°C, below 45°C, below 40°C, below 35°C or below 30°C. In some embodiments, the temperature at which the composite is immersed in the stripping solution is above 10°C, above 15°C, above 20°C, above 25°C, above 30°C, above 35°C, above 40°C, above 45°C, above 50°C, above 55°C, above 60°C, above 65°C or above 70°C.

[0133] When the amount of stripping solution used to immerse a certain amount of composite is insufficient, complete stripping of the composite does not occur. An example of the result is that a large portion of the coating is still found to adhere or stick to the surface of the metal substrate. In terms of the stripping effect, there is no particular disadvantage in using too much stripping solution, but this will cause waste of raw materials and may generate unnecessary contaminated aqueous solvent waste, and further processing steps are required to make the solvent reusable. Therefore, except that the ratio of the stripping solution to the composite should be sufficient to strip all the composite, there is no particular limitation on the ratio of the composite to the stripping solution, and considering cost reasons, it is not recommended to use an excessive ratio of the stripping agent to the composite.

[0134] In some embodiments, when the composite is immersed in a stripping solution to effect stripping of the composite, the weight ratio of the composite to the stripping solution is from about 0.01% to about 50%, from about 0.02% to about 50%, from about 0.05% to about 50%, from about 0.1% to about 50%, from about 0.2% to about 50%, from about 0.5% to about 50%, from about 1% to about 50%, from about 2% to about 50%, from about 5% to about 50%, from about 10% to about 50%, from about 15% to about 50%, from about 20% to about 50%, from about 25% to about 50%, from about 30% to about 50%, from about 0.01% to about 25%, from about 0.02% to about 25%, from about 0.05% to about 25%, from about 0.1% to about 25%, from about 0.2% to about 25%, from about 0.5% to about 25%, from about 1% to about 25%, from about 2% to about 25%, from about 5% to about 25%, from about 10% to about 25%, from about 0.1% to about 15%, from about 0.2% to about 15%, from about 0.5% to about 15%, from about 1% to about 15%, from about 2% to about 15%, from about 5% to about 15%, from about 0.1% to about 5%, from about 0.2% to about 5%, from about 0.5% to about 5%, from about 1% to about 5%, or from about 2% to about 5%.

[0135] In some embodiments, when the composite is immersed in a stripping solution to effect stripping of the composite, the weight ratio of the composite to the stripping solution is less than 50%, less than 45%, less than 40%, less than 35%, less than 30%, less than 25%, less than 20%, less than 15%, less than 10%, less than 5%, less than 2%, less than 1%, less than 0.5%, less than 0.2%, less than 0.1%, or less than 0.05%. In some embodiments, when the composite is immersed in a stripping solution to effect stripping of the composite, the weight ratio of the composite to the stripping solution is greater than 0.01%, greater than 0.02%, greater than 0.05%, greater than 0.1%, greater than 0.2%, greater than 0.5%, greater than 1%, greater than 2%, greater than 5%, greater than 10%, greater than 15%, greater than 20%, greater than 25%, greater than 30%, greater than 35%, or greater than 40%.

[0136] The purpose of the stripping agent is to interrupt and disrupt the ion-dipole interactions and hydrogen bond interactions between the copolymer binder contained in the coating and the surface of the metal substrate. A sufficient concentration of the stripping agent in the stripping solution is required to effectively disrupt the interactions between the coating and the metal substrate, thereby enabling stripping of the composite. A relatively low concentration of the stripping agent is sufficient to cause disruption of the interactions between the copolymer binder in the coating and the surface of the metal substrate. Immersing the composite in a low concentration of the stripping agent can reduce the likelihood of corrosion of the metal substrate and other possible metal components in the composite and / or reduce side reactions that may be caused by using a high concentration of the stripping agent.

[0137] In some embodiments, the concentration of the stripping agent in the stripping solution is from about 0.3 M to about 3 M, from about 0.5 M to about 3 M, from about 0.75 M to about 3 M, from about 1 M to about 3 M, from about 1.25 M to about 3 M, from about 1.5 M to about 3 M, from about 1.75 M to about 3 M, from about 2 M to about 3 M, from about 2.25 M to about 3 M, from about 2.5 M to about 3 M, from about 0.3 M to about 2.5 M, from about 0.5 M to about 2.5 M, from about 0.75 M to about 2.5 M, from about 1 M to about 2.5 M, from about 1.25 M to about 2.5 M, from about 1.5 M to about 2.5 M, from about 1.75 M to about 2.5 M, from about 0.3 M to about 2 M, from about 0.5 M to about 2 M, from about 0.75 M to about 2 M, from about 1 M to about 2 M, from about 1.25 M to about 2 M, from about 0.3 M to about 1.5 M, from about 0.5 M to about 1.5 M, from about 0.75 M to about 1.5 M, or from about 1 M to about 1.5 M.

[0138] In some embodiments, the concentration of the stripping agent in the stripping solution is less than 3 M, less than 2.75 M, less than 2.5 M, less than 2.25 M, less than 2 M, less than 1.75 M, less than 1.5 M, less than 1.25 M, less than 1 M, or less than 0.75 M. In some embodiments, the concentration of the stripping agent in the stripping solution is greater than 0.3 M, greater than 0.5 M, greater than 0.75 M, greater than 1 M, greater than 1.25 M, greater than 1.5 M, greater than 1.75 M, greater than 2 M, greater than 2.25 M, or greater than 2.5 M.

[0139] In some embodiments, the surface density of the coating is from about 1 mg / cm 2 to about 50 mg / cm 2 、from about 2.5 mg / cm 2 to about 50 mg / cm 2 、from about 5 mg / cm 2 to about 50 mg / cm 2 、from about 7.5 mg / cm 2 to about 50 mg / cm 2 、from about 10 mg / cm 2 to about 50 mg / cm 2 、from about 12.5 mg / cm 2 to about 50 mg / cm 2 、from about 15 mg / cm 2 to about 50 mg / cm 2 、from about 17.5 mg / cm 2 to about 50 mg / cm 2 、from about 20 mg / cm 2 to about 50 mg / cm 2 、from about 25 mg / cm 2 to about 50 mg / cm 2, about 30 mg / cm 2 to about 50 mg / cm 2 , about 1 mg / cm 2 to about 30 mg / cm 2 , about 2.5 mg / cm 2 to about 30 mg / cm 2 , about 5 mg / cm 2 to about 30 mg / cm 2 , about 7.5 mg / cm 2 to about 30 mg / cm 2 , about 10 mg / cm 2 to about 30 mg / cm 2 , about 12.5 mg / cm 2 to about 30 mg / cm 2 , about 15 mg / cm 2 to about 30 mg / cm 2 , about 17.5 mg / cm 2 to about 30 mg / cm 2 , about 20 mg / cm 2 to about 30 mg / cm 2 , about 1 mg / cm 2 to about 20 mg / cm 2 , about 2.5 mg / cm 2 to about 20 mg / cm 2 , about 5 mg / cm 2 to about 20 mg / cm 2 , about 7.5 mg / cm 2 to about 20 mg / cm 2 , about 10 mg / cm 2 to about 20 mg / cm 2 , about 12.5 mg / cm 2 to about 20 mg / cm 2 , about 1 mg / cm 2 to about 15 mg / cm 2 , about 2.5 mg / cm 2 to about 15 mg / cm 2 , about 5 mg / cm 2 to about 15 mg / cm 2 , about 7.5 mg / cm 2 to about 15 mg / cm 2 or about 10 mg / cm 2 to about 15 mg / cm 2 .

[0140] In some embodiments, the surface density of the coating is less than 50 mg / cm 2, less than 45 mg / cm 2 , less than 35 mg / cm 2 , less than 30 mg / cm 2 , less than 25 mg / cm 2 , less than 20 mg / cm 2 , less than 17.5 mg / cm 2 , less than 15 mg / cm 2 , less than 12.5 mg / cm 2 , less than 10 mg / cm 2 , less than 7.5 mg / cm 2 , less than 5 mg / cm 2 or less than 2.5 mg / cm 2 . In some embodiments, the surface density of the coating is greater than 1 mg / cm 2 , greater than 2.5 mg / cm 2 , greater than 5 mg / cm 2 , greater than 7.5 mg / cm 2 , greater than 10 mg / cm 2 , greater than 12.5 mg / cm 2 , greater than 15 mg / cm 2 , greater than 17.5 mg / cm 2 , greater than 20 mg / cm 2 , greater than 25 mg / cm 2 , greater than 30 mg / cm 2 , greater than 35 mg / cm 2 or greater than 40 mg / cm 2 .

[0141] In some embodiments, the density of the coating is from about 0.5 g / cm 3 to about 7.5 g / cm 3 , from about 1 g / cm 3 to about 7.5 g / cm 3 , from about 1.5 g / cm 3 to about 7.5 g / cm 3 , from about 2 g / cm 3 to about 7.5 g / cm 3 , from about 2.5 g / cm 3 to about 7.5 g / cm 3 , from about 3 g / cm 3 to about 7.5 g / cm 3 , from about 3.5 g / cm 3 to about 7.5 g / cm 3 , from about 4 g / cm 3 to about 7.5 g / cm 3 , from about 4.5 g / cm3 to about 7.5 g / cm 3 、about 5 g / cm 3 to about 7.5 g / cm 3 、about 0.5 g / cm 3 to about 5 g / cm 3 、about 1 g / cm 3 to about 5 g / cm 3 、about 1.5 g / cm 3 to about 5 g / cm 3 、about 2 g / cm 3 to about 5 g / cm 3 、about 2.5 g / cm 3 to about 5 g / cm 3 、about 3 g / cm 3 to about 5 g / cm 3 、about 0.5 g / cm 3 to about 2.5 g / cm 3 、about 1 g / cm 3 to about 2.5 g / cm 3 or about 1.5 g / cm 3 to about 2.5 g / cm 3 。

[0142] In some embodiments, the density of the coating is less than 7.5 g / cm 3 、less than 7 g / cm 3 、less than 6.5 g / cm 3 、less than 6 g / cm 3 、less than 5.5 g / cm 3 、less than 5 g / cm 3 、less than 4.5 g / cm 3 、less than 4 g / cm 3 、less than 3.5 g / cm 3 、less than 3 g / cm 3 、less than 2.5 g / cm 3 、less than 2 g / cm 3 or less than 1.5 g / cm 3 。In some embodiments, the density of the coating is greater than 0.5 g / cm 3 、greater than 1 g / cm 3 、greater than 1.5 g / cm 3 、greater than 2 g / cm 3 、greater than 2.5 g / cm 3 、greater than 3 g / cm 3 、greater than 3.5 g / cm 3 、greater than 4 g / cm 3 、greater than 4.5 g / cm 3 、greater than 5 g / cm3 、 greater than 5.5 g / cm 3 、 greater than 6 g / cm 3 or greater than 6.5 g / cm 3 。

[0143] In some embodiments, when the composite is immersed in the stripping solution, the composite-stripping solution mixture can be stirred to effect stripping of the composite. In some embodiments, a planetary stirring mixer, a stirring mixer, a mixer, an ultrasonic generator, or a combination thereof is used to stir the composite-stripping solution mixture. In other embodiments, when the composite is immersed in the stripping solution, the composite-stripping solution mixture is not stirred.

[0144] In some embodiments, the speed of stirring the composite-stripping solution mixture is about 10 rpm to about 3000 rpm, about 20 rpm to about 3000 rpm, about 50 rpm to about 3000 rpm, about 100 rpm to about 3000 rpm, about 200 rpm to about 3000 rpm, about 250 rpm to about 3000 rpm, about 300 rpm to about 3000 rpm, about 400 rpm to about 3000 rpm, about 500 rpm to about 3000 rpm, about 600 rpm to about 3000 rpm, about 750 rpm to about 3000 rpm, about 900 rpm to about 3000 rpm, about 1200 rpm to about 3000 rpm, about 1500 rpm to about 3000 rpm, about 10 rpm to about 1000 rpm, about 20 rpm to about 1000 rpm, about 50 rpm to about 1000 rpm, about 100 rpm to about 1000 rpm, about 200 rpm to about 1000 rpm, about 250 rpm to about 1000 rpm, about 300 rpm to about 1000 rpm, about 400 rpm to about 1000 rpm, about 500 rpm to about 1000 rpm, about 10 rpm to about 750 rpm, about 20 rpm to about 750 rpm, about 50 rpm to about 750 rpm, about 100 rpm to about 750 rpm, about 200 rpm to about 750 rpm, about 250 rpm to about 750 rpm, about 300 rpm to about 750 rpm, about 10 rpm to about 500 rpm, about 20 rpm to about 500 rpm, about 50 rpm to about 500 rpm, about 100 rpm to about 500 rpm, or about 200 rpm to about 500 rpm.

[0145] In some embodiments, the speed of stirring the complex-exfoliation solution mixture is less than 3000 rpm, less than 2500 rpm, less than 1500 rpm, less than 1200 rpm, less than 900 rpm, less than 750 rpm, less than 600 rpm, less than 500 rpm, less than 400 rpm, less than 300 rpm or less than 250 rpm. In some embodiments, the speed of stirring the complex-exfoliation solution mixture is greater than 10 rpm, greater than 20 rpm, greater than 50 rpm, greater than 100 rpm, greater than 200 rpm, greater than 250 rpm, greater than 300 rpm, greater than 400 rpm, greater than 500 rpm, greater than 600 rpm or greater than 750 rpm.

[0146] In some embodiments, the time for stirring the complex-exfoliation solution mixture is from about 1 second to about 120 minutes, from about 5 seconds to about 120 minutes, from about 10 seconds to about 120 minutes, from about 20 seconds to about 120 minutes, from about 30 seconds to about 120 minutes, from about 45 seconds to about 120 minutes, from about 60 seconds to about 120 minutes, from about 75 seconds to about 120 minutes, from about 90 seconds to about 120 minutes, from about 105 seconds to about 120 minutes, from about 120 seconds to about 120 minutes, from about 30 seconds to about 90 minutes, from about 30 seconds to about 75 minutes, from about 30 seconds to about 60 minutes, from about 30 seconds to about 45 minutes, from about 30 seconds to about 30 minutes, from about 30 seconds to about 20 minutes, from about 30 seconds to about 10 minutes, from about 30 seconds to about 5 minutes, from about 60 seconds to about 90 minutes, from about 60 seconds to about 75 minutes, from about 60 seconds to about 60 minutes, from about 60 seconds to about 45 minutes, from about 60 seconds to about 30 minutes, from about 60 seconds to about 20 minutes, from about 60 seconds to about 10 minutes, from about 60 seconds to about 5 minutes, from about 120 seconds to about 60 minutes, from about 120 seconds to about 45 minutes, from about 120 seconds to about 30 minutes, from about 120 seconds to about 20 minutes, from about 120 seconds to about 10 minutes or from about 120 seconds to about 5 minutes.

[0147] In some embodiments, the time for stirring the complex-exfoliation solution mixture is less than 120 minutes, less than 105 minutes, less than 90 minutes, less than 75 minutes, less than 60 minutes, less than 45 minutes, less than 30 minutes, less than 20 minutes, less than 10 minutes, less than 5 minutes, less than 1 minute, less than 45 seconds, less than 30 seconds, less than 20 seconds or less than 10 seconds. In some embodiments, the time for stirring the complex-exfoliation solution mixture is more than 1 second, more than 5 seconds, more than 10 seconds, more than 20 seconds, more than 30 seconds, more than 45 seconds, more than 60 seconds, more than 75 seconds, more than 90 seconds, more than 105 seconds, more than 120 seconds, more than 5 minutes, more than 10 minutes, more than 20 minutes or more than 30 minutes.

[0148] In some embodiments, the planetary stirring mixer includes at least one planetary paddle and at least one high-speed dispersing paddle. In certain embodiments, the rotational speed of the planetary paddle is about 20 rpm to about 200 rpm, about 20 rpm to about 150 rpm, about 30 rpm to about 150 rpm, or about 50 rpm to about 100 rpm. In certain embodiments, the rotational speed of the dispersing paddle is about 1000 rpm to about 4000 rpm, about 1000 rpm to about 3500 rpm, about 1000 rpm to about 3000 rpm, about 1000 rpm to about 2000 rpm, about 1500 rpm to about 3000 rpm, or about 1500 rpm to about 2500 rpm.

[0149] In certain embodiments, the ultrasonic generator is an ultrasonic bath, a probe-type ultrasonic generator, or an ultrasonic flow cell. In some embodiments, the power density during the operation of the ultrasonic generator is about 10 W / L to about 100 W / L, about 20 W / L to about 100 W / L, about 30 W / L to about 100 W / L, about 40 W / L to about 80 W / L, about 40 W / L to about 70 W / L, about 40 W / L to about 60 W / L, about 40 W / L to about 50 W / L, about 50 W / L to about 60 W / L, about 20 W / L to about 80 W / L, about 20 W / L to about 60 W / L, or about 20 W / L to about 40 W / L. In certain embodiments, the power density during the operation of the ultrasonic generator is greater than 10 W / L, greater than 20 W / L, greater than 30 W / L, greater than 40 W / L, greater than 50 W / L, greater than 60 W / L, greater than 70 W / L, greater than 80 W / L, or greater than 90 W / L.

[0150] In some embodiments, the power during the operation of the ultrasonic generator is about 100 W to about 1000 W, about 200 W to about 1000 W, about 300 W to about 1000 W, about 400 W to about 1000 W, about 500 W to about 1000 W, about 500 W to about 900 W, about 500 W to about 800 W, about 500 W to about 700 W, or about 500 W to about 600 W. In some embodiments, the power during the operation of the ultrasonic generator is less than 1000 W, less than 900 W, less than 800 W, less than 700 W, less than 600 W, less than 500 W, less than 400 W, or less than 300 W. In some embodiments, the power during the operation of the ultrasonic generator is greater than 100 W, greater than 200 W, greater than 300 W, greater than 400 W, greater than 500 W, greater than 600 W, greater than 700 W, or greater than 800 W.

[0151] In some embodiments, after the composite is immersed in the stripping solution, the pH value of the stripped composite-stripping solution mixture is from about 10 to about 14, from about 10.25 to about 14, from about 10.5 to about 14, from about 10.75 to about 14, from about 11 to about 14, from about 11.25 to about 14, from about 11.5 to about 14, from about 11.5 to about 13.75, from about 11.5 to about 13.5, from about 11.5 to about 13.25, from about 11.5 to about 13, from about 11.5 to about 12.75 or from about 11.5 to about 12.5.

[0152] In some embodiments, after the composite is immersed in the stripping solution, the pH value of the stripped composite-stripping solution mixture is less than 14, less than 13.75, less than 13.5, less than 13.25, less than 13, less than 12.75, less than 12.5, less than 12.25, less than 12, less than 11.75 or less than 11.5. In some embodiments, after the composite is immersed in the stripping solution, the pH value of the stripped composite-stripping solution mixture is greater than 10, greater than 10.25, greater than 10.5, greater than 10.75, greater than 11, greater than 11.25, greater than 11.5, greater than 11.75, greater than 12, greater than 12.25 or greater than 12.5.

[0153] In some embodiments, after the composite is immersed in the stripping solution, the composite is stripped into two or more layers. In some embodiments, after the composite is immersed in the stripping solution, the composite is stripped into a coating and a metal-based substrate layer.

[0154] In some embodiments, the stripped composite-stripping solution mixture is screened to separate the coating and the metal-based substrate layer from the stripping solution. In some embodiments, filtration, sieving, decantation or a combination thereof can be used to screen the stripped composite-stripping solution mixture.

[0155] Figure 3 is a flow chart of an embodiment that shows the steps in method 300 for the stripping of the composites disclosed herein and subsequent further processes for extracting the coating and the metal substrate material. Since the tendency of the metal substrate in the present invention to corrode and dissolve is quite low, it is not necessary to purify the extracted stripping solution for further reuse. The extracted stripping solution can be reused for the stripping of other composites. This forms a closed-loop recycling process in which materials can be repeatedly recycled and reused and continuously participate in the cycle, which helps to create a circular economy.

[0156] In some embodiments, additional separation and / or extraction processes may be performed on the recovered delaminated composite materials to further extract the materials contained therein. In some embodiments, additional separation and / or extraction processes may be performed on the recovered coating and metal-based substrate to further extract the coating and metal substrate materials.

[0157] The method of the present invention is particularly suitable for achieving delamination of electrodes in a battery, where the electrode is a composite, and the electrode layer and the current collector are a coating and a metal substrate, respectively.

[0158] In some embodiments, the battery may be a primary battery or a secondary battery. Some non-limiting examples of the battery include alkaline batteries, aluminum-air batteries, lithium batteries, lithium-air batteries, magnesium batteries, solid-state batteries, silver oxide batteries, zinc-air batteries, aluminum-ion batteries, lead-acid batteries, lithium-ion batteries, magnesium-ion batteries, potassium-ion batteries, sodium-ion batteries, lithium-air batteries, aluminum-air batteries, zinc-air batteries, sodium-air batteries, silicon-air batteries, zinc-ion batteries, and sodium-sulfur batteries.

[0159] Within the electrode, a binder can be used to adhere the active material particles and the conductive agent to the current collector to form a continuous conduction path. Since the copolymer binder disclosed herein has excellent adhesion ability, this copolymer binder can be used. Due to the good adhesion ability between the electrode layer components and between the electrode layer and the current collector, using this copolymer binder helps to reduce the impedance and interface resistance between the current collector and the electrode material, thereby improving the ion and electron transport rates. In addition, the disclosed copolymer can easily interact with water through hydrogen bonds and ion-dipole interactions, making the copolymer binder have excellent dispersibility and stability in water. By using an aqueous slurry, it has good processability when forming the electrode layer.

[0160] When recycling a battery, there are disadvantages in stripping the electrode layer from the current collector using current methods, such as the need for high temperature and release of harmful substances when using the calcination method, or the need to use dangerous and harmful chemicals when using the leaching method.

[0161] In contrast, the delamination method disclosed herein can effectively delaminate an electrode comprising a current collector and an electrode layer coated on one or both sides of the current collector (where the electrode layer comprises the copolymer binder disclosed in the present invention) by simply using a delamination solution, without significant safety issues or environmental impacts. In addition, the delamination process is very efficient.

[0162] Figure 4Describes the cathode layer and current collector recovered in Example 4 after immersing a double-sided coated cathode in a stripping solution, where the cathode contains a copolymer binder, and where the stripping solution contains sodium hydroxide at a concentration of 1 M and deionized water. It can be seen that the cathode layer is completely stripped from the aluminum current collector, and no discoloration or pitting of the aluminum current collector is observed, indicating no obvious corrosion of the aluminum current collector.

[0163] Figure 5 Describes the recovered cathode in Comparative Example 1, where the double-sided coated cathode immersed in the stripping solution contains polyvinylidene fluoride (PVDF) as a polymer binder. The stripping solution used herein contains sodium hydroxide at a concentration of 0.5 M and deionized water. It can be seen that the stripping of the cathode layer from the aluminum current collector is unsuccessful, and although immersed in the stripping solution, the cathode layer still adheres firmly to the aluminum current collector. This indicates that using the stripping agent disclosed in the present invention for electrode stripping is not applicable to electrodes containing non-aqueous polymer binders (such as PVDF).

[0164] A current collector is used to collect electrons generated by the electrochemical reaction of the cathode active material or to provide electrons required for the electrochemical reaction. In some embodiments, the current collector can be in the form of a foil, sheet, or film. In some embodiments, the current collector is a metal. In some embodiments, the current collector is selected from the group consisting of stainless steel, titanium, nickel, aluminum, copper, platinum, gold, silver, chromium, zirconium, tungsten, molybdenum, tin, vanadium, zinc, cadmium, iron, cobalt, lead, and their alloys. In some embodiments, the current collector has only one layer. In some embodiments, the current collector has a two-layer structure. In some embodiments, the current collector has three or more layers. In some embodiments, one or more materials in each layer can be the same, different, or partially different.

[0165] In some embodiments, when the current collector contains more than one layer, the current collector contains a layer of insulating material. In some embodiments, the insulating material is a polymeric material selected from the group consisting of polycarbonate, polyacrylate, polyacrylonitrile, polyester, polyamide, polystyrene, polyurethane, polyepoxy resin, poly(acrylonitrile butadiene styrene), polyimide, polyolefin, polyethylene, polypropylene, polyphenylene sulfide, poly(vinyl ester), polyvinyl chloride, polyether, polyphenylene ether, cellulose polymers, and combinations thereof. When the current collector contains an insulating material layer, the coating is applied to the metal layer on the outside of the current collector.

[0166] In some embodiments, the current collector is coated with a layer of carbonaceous material. This layer of carbonaceous material will be part of the coating. In some embodiments, the current collector is not coated with a layer of carbonaceous material.

[0167] The thickness of the current collector affects the volume it occupies in the battery and the amount of electrode active material required, thereby affecting the capacity of the battery. In some embodiments, the thickness of the current collector is about 5 μm to about 50 μm, about 10 μm to about 50 μm, about 15 μm to about 50 μm, about 20 μm to about 50 μm, about 25 μm to about 50 μm, about 5 μm to about 30 μm, about 10 μm to about 30 μm, about 15 μm to about 30 μm, about 20 μm to about 30 μm, about 5 μm to about 20 μm, about 5 μm to about 15 μm, about 10 μm to about 30 μm, about 10 μm to about 25 μm, or about 10 μm to about 20 μm.

[0168] In some embodiments, the thickness of the current collector is less than 50 μm, less than 45 μm, less than 40 μm, less than 35 μm, less than 30 μm, less than 25 μm, less than 20 μm, less than 15 μm, or less than 10 μm. In some embodiments, the thickness of the current collector is greater than 5 μm, greater than 10 μm, greater than 15 μm, greater than 20 μm, greater than 25 μm, greater than 30 μm, greater than 35 μm, greater than 40 μm, or greater than 45 μm.

[0169] In some embodiments, the electrode can be a cathode or an anode. In some embodiments, the electrode layer further comprises an electrode active material.

[0170] In some embodiments, the electrode active material is a cathode active material, wherein the cathode active material is selected from the group consisting of LiCoO2, LiNiO2, LiNi x Mn y O2, LiCo x Ni y O2, Li 1+z Ni x Mn y Co 1-x-y O2, LiNi x Co y Al zThe group consisting of O2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, Li2MnO3, LiFeO2, LiFePO4, and combinations thereof, wherein each x is independently from 0.1 to 0.9; each y is independently from 0 to 0.9; each z is independently from 0 to 0.4. In certain embodiments, each x in the above general formula is independently selected from 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4, 0.425, 0.45, 0.475, 0.5, 0.525, 0.55, 0.575, 0.6, 0.625, 0.65, 0.675, 0.7, 0.725, 0.75, 0.775, 0.8, 0.825, 0.85, 0.875, and 0.9; each y in the above general formula is independently selected from 0, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4, 0.425, 0.45, 0.475, 0.5, 0.525, 0.55, 0.575, 0.6, 0.625, 0.65, 0.675, 0.7, 0.725, 0.75, 0.775, 0.8, 0.825, 0.85, 0.875, and 0.9; each z in the above general formula is independently selected from 0, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, and 0.4. In some embodiments, each x, y, and z in the above general formula independently has an interval of 0.01.

[0171] In certain embodiments, the cathode active material is selected from the group consisting of LiCoO2, LiNiO2, LiNi x Mn y O2, Li 1+ z Ni x Mn y Co 1-x-y O2 (NMC), LiNi x Co y Al z O2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, LiFeO2, LiFePO4, LiCo x Ni yA group consisting of O2 and its combinations, where each x is independently from 0.4 to 0.6; each y is independently from 0.2 to 0.4; and each z is independently from 0 to 0.1. In other embodiments, the cathode active material is not LiCoO2, LiNiO2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, LiFeO2 or LiFePO4. In further embodiments, the cathode active material is not LiNi x Mn y O2, Li 1+z Ni x Mn y Co 1-x-y O2, LiNi x Co y Al z O2 or LiCo x Ni y O2, where each x is independently from 0.1 to 0.9; each y is independently from 0 to 0.45; and each z is independently from 0 to 0.2. In certain embodiments, the cathode active material is Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2; where -0.2 ≤ x ≤ 0.2, 0 ≤ a < 1, 0 ≤ b < 1, 0 ≤ c < 1 and a + b + c ≤ 1. In some embodiments, the cathode active material has the general formula Li 1+x Ni a Mn b Co c Al (1-a-b-c)O2, where 0.33 ≤ a ≤ 0.92, 0.33 ≤ a ≤ 0.9, 0.33 ≤ a ≤ 0.8, 0.4 ≤ a ≤ 0.92, 0.4 ≤ a ≤ 0.9, 0.4 ≤ a ≤ 0.8, 0.5 ≤ a ≤ 0.92, 0.5 ≤ a ≤ 0.9, 0.5 ≤ a ≤ 0.8, 0.6 ≤ a ≤ 0.92 or 0.6 ≤ a ≤ 0.9; 0 ≤ b ≤ 0.5, 0 ≤ b ≤ 0.4, 0 ≤ b ≤ 0.3, 0 ≤ b ≤ 0.2, 0.1 ≤ b ≤ 0.5, 0.1 ≤ b ≤ 0.4, 0.1 ≤ b ≤ 0.3, 0.1 ≤ b ≤ 0.2, 0.2 ≤ b ≤ 0.5, 0.2 ≤ b ≤ 0.4 or 0.2 ≤ b ≤ 0.3; 0 ≤ c ≤ 0.5, 0 ≤ c ≤ 0.4, 0 ≤ c ≤ 0.3, 0.1 ≤ c ≤ 0.5, 0.1 ≤ c ≤ 0.4, 0.1 ≤ c ≤ 0.3, 0.1 ≤ c ≤ 0.2, 0.2 ≤ c ≤ 0.5, 0.2 ≤ c ≤ 0.4 or 0.2 ≤ c ≤ 0.3. In some embodiments, the cathode active material has the general formula LiMPO4, where M is selected from the group consisting of Fe, Co, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof. In some embodiments, the cathode active material is selected from the group consisting of LiFePO4, LiCoPO4, LiNiPO4, LiMnPO4, LiMnFePO4, LiMn x Fe (1-x) PO4, and combinations thereof; where 0 < x < 1. In some embodiments, the cathode active material is LiNi x Mn y O4; where 0.1 ≤ x ≤ 0.9 and 0 ≤ y ≤ 2. In certain embodiments, the cathode active material is xLi2MnO3·(1 - x)LiMO2, where M is selected from the group consisting of Ni, Co, Mn, and combinations thereof; and where 0 < x < 1. In some embodiments, the cathode active material is Li3V2(PO4)3 or LiVPO4F. In certain embodiments, the cathode active material has the general formula Li2MSiO4, where M is selected from the group consisting of Fe, Co, Mn, Ni, and combinations thereof.

[0172] In certain embodiments, the cathode active material is doped with a dopant selected from the group consisting of Co, Cr, V, Mo, Nb, Pd, F, Na, Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof. In some embodiments, the dopant is not Co, Cr, V, Mo, Nb, Pd, F, Na, Fe, Ni, Mn, Mg, Zn, Ti, La, Ce, Ru, Si, or Ge. In certain embodiments, the dopant is not Al, Sn, or Zr.

[0173] In some embodiments, the cathode active material is LiNi 0.33 Mn 0.33 Co 0.33 O2 (NMC333), LiNi 0.4 Mn 0.4 Co 0.2 O2, LiNi 0.5 Mn 0.3 Co 0.2 O2 (NMC532), LiNi 0.6 Mn 0.2 Co 0.2 O2 (NMC622), LiNi 0.7 Mn 0.15 Co 0.15 O2, LiNi 0.7 Mn 0.1 Co 0.2 O2, LiNi 0.8 Mn 0.1 Co 0.1 O2 (NMC811), LiNi 0.92 Mn 0.04 Co 0.04 O2, LiNi 0.8 Co 0.15 Al 0.05 O2 (NCA), LiNiO2 (LNO), or a combination thereof.

[0174] In other embodiments, the cathode active material is not LiCoO2, LiNiO2, LiMnO2, LiMn2O4, or Li2MnO3. In further embodiments, the cathode active material is not LiNi 0.33 Mn 0.33 Co 0.33 O2, LiNi 0.4 Mn 0.4 Co 0.2 O2, LiNi 0.5 Mn 0.3 Co 0.2 O2, LiNi 0.6 Mn 0.2 Co 0.2 O2, LiNi 0.7 Mn 0.15 Co 0.15 O2, LiNi 0.7 Mn 0.1 Co 0.2 O2, LiNi 0.8 Mn 0.1 Co 0.1 O2, LiNi 0.92 Mn 0.04Co 0.04 O2 or LiNi 0.8 Co 0.15 Al 0.05 O2.

[0175] In certain embodiments, the cathode active material comprises or is itself a core-shell composite having a core and a shell structure, wherein the core and the shell each independently comprise a material selected from the group consisting of Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li2MnO3, LiCrO2, Li4Ti5O 12 , LiV2O5, LiTiS2, LiMoS2, LiCo a Ni b O2, LiMn a Ni bLithium transition metal oxides of the group consisting of O2 and its combinations, where -0.2 ≤ x ≤ 0.2, 0 ≤ a < 1, 0 ≤ b < 1, 0 ≤ c < 1, and a + b + c ≤ 1. In certain embodiments, each x in the above general formula is independently selected from -0.2, -0.175, -0.15, -0.125, -0.1, -0.075, -0.05, -0.025, 0, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, and 0.2; each a in the above general formula is independently selected from 0, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4, 0.425, 0.45, 0.475, 0.5, 0.525, 0.55, 0.575, 0.6, 0.625, 0.65, 0.675, 0.7, 0.725, 0.75, 0.775, 0.8, 0.825, 0.85, 0.875, 0.9, 0.925, 0.95, and 0.975; each b in the above general formula is independently selected from 0, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4, 0.425, 0.45, 0.475, 0.5, 0.525, 0.55, 0.575, 0.6, 0.625, 0.65, 0.675, 0.7, 0.725, 0.75, 0.775, 0.8, 0.825, 0.85, 0.875, 0.9, 0.925, 0.95, and 0.975; each c in the above general formula is independently selected from 0, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4, 0.425, 0.45, 0.475, 0.5, 0.525, 0.55, 0.575, 0.6, 0.625, 0.65, 0.675, 0.7, 0.725, 0.75, 0.775, 0.8, 0.825, 0.85, 0.875, 0.9, 0.925, 0.95, and 0.975. In some embodiments, each x, a, b, and c in the above general formula independently has an interval of 0.01. In other embodiments, the core and the shell each independently contain two or more lithium transition metal oxides. In some embodiments, one of the core or the shell contains only one lithium transition metal oxide, while the other contains two or more lithium transition metal oxides. The lithium transition metal oxides in the core and the shell can be the same, different, or partially different.In some embodiments, two or more lithium transition metal oxides are uniformly distributed on the core. In certain embodiments, two or more lithium transition metal oxides are non-uniformly distributed on the core. In some embodiments, the cathode active material is not a core-shell composite material.

[0176] In some embodiments, each of the lithium transition metal oxides in the core and the shell is independently doped with a dopant selected from the group consisting of Co, Cr, V, Mo, Nb, Pd, F, Na, Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof. In certain embodiments, the core and the shell each independently comprise two or more doped lithium transition metal oxides. In some embodiments, two or more doped lithium transition metal oxides are uniformly distributed on the core and / or the shell. In certain embodiments, two or more doped lithium transition metal oxides are non-uniformly distributed on the core and / or the shell.

[0177] In some embodiments, the cathode active material comprises or is itself a core-shell composite material, which comprises a core containing a lithium transition metal oxide and a shell containing a transition metal oxide. In certain embodiments, the lithium transition metal oxide is selected from the group consisting of Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li2MnO3, LiCrO2, Li4Ti5O 12 , LiV2O5, LiTiS2, LiMoS2, LiCo a Ni b O2, LiMn a Ni bGroups composed of O2 and its combinations; where -0.2 ≤ x ≤ 0.2, 0 ≤ a < 1, 0 ≤ b < 1, 0 ≤ c < 1, and a + b + c ≤ 1. In certain embodiments, x in the above general formula is independently selected from -0.2, -0.175, -0.15, -0.125, -0.1, -0.075, -0.05, -0.025, 0, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, and 0.2; each a in the above general formula is independently selected from 0, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4, 0.425, 0.45, 0.475, 0.5, 0.525, 0.55, 0.575, 0.6, 0.625, 0.65, 0.675, 0.7, 0.725, 0.75, 0.775, 0.8, 0.825, 0.85, 0.875, 0.9, 0.925, 0.95, and 0.975; each b in the above general formula is independently selected from 0, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4, 0.425, 0.45, 0.475, 0.5, 0.525, 0.55, 0.575, 0.6, 0.625, 0.65, 0.675, 0.7, 0.725, 0.75, 0.775, 0.8, 0.825, 0.85, 0.875, 0.9, 0.925, 0.95, and 0.975; each c in the above general formula is independently selected from 0, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4, 0.425, 0.45, 0.475, 0.5, 0.525, 0.55, 0.575, 0.6, 0.625, 0.65, 0.675, 0.7, 0.725, 0.75, 0.775, 0.8, 0.825, 0.85, 0.875, 0.9, 0.925, 0.95, and 0.975. In some embodiments, each x, a, b, and c in the above general formula independently has an interval of 0.01. In some embodiments, the transition metal oxide is selected from the group consisting of Fe2O3, MnO2, Al2O3, MgO, ZnO, TiO2, La2O3, CeO2, SnO2, ZrO2, RuO2, and combinations thereof. In certain embodiments, the shell contains lithium transition metal oxide and transition metal oxide.

[0178] In some embodiments, the diameter of the core is about 1 μm to about 15 μm, about 3 μm to about 15 μm, about 3 μm to about 10 μm, about 5 μm to about 10 μm, about 5 μm to about 45 μm, about 5 μm to about 35 μm, about 5 μm to about 25 μm, about 10 μm to about 45 μm, about 10 μm to about 40 μm, about 10 μm to about 35 μm, about 10 μm to about 25 μm, about 15 μm to about 45 μm, about 15 μm to about 30 μm, about 15 μm to about 25 μm, about 20 μm to about 35 μm, or about 20 μm to about 30 μm. In certain embodiments, the thickness of the shell is about 1 μm to about 45 μm, about 1 μm to about 35 μm, about 1 μm to about 25 μm, about 1 μm to about 15 μm, about 1 μm to about 10 μm, about 1 μm to about 5 μm, about 3 μm to about 15 μm, about 3 μm to about 10 μm, about 5 μm to about 10 μm, about 10 μm to about 35 μm, about 10 μm to about 20 μm, about 15 μm to about 30 μm, about 15 μm to about 25 μm, or about 20 μm to about 35 μm. In certain embodiments, the ratio of the diameter or thickness of the core to the shell is in the range of 15:85 to 85:15, 25:75 to 75:25, 30:70 to 70:30, or 40:60 to 60:40. In certain embodiments, the volume or weight ratio of the core to the shell is 95:5, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, or 30:70.

[0179] In some embodiments, the electrode active material is an anode active material, wherein the anode active material is selected from the group consisting of natural graphite particles, synthetic graphite particles, hard carbon, soft carbon, mesocarbon microbeads (MCMB), Sn particles, SnO2, SnO, Li4Ti5O 12 particles, Si particles, Si-C composite particles, and combinations thereof.

[0180] In certain embodiments, the anode active material is doped with a metal element or a non-metal element. In some embodiments, the metal element is selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, and combinations thereof. In some embodiments, the non-metal element is B, Si, Ge, N, P, F, S, Cl, I, Se, or a combination thereof.

[0181] In some embodiments, the anode active material comprises or itself is a core-shell composite material having a core and a shell structure, wherein the core and the shell are each independently selected from the group consisting of natural graphite particles, synthetic graphite particles, hard carbon, soft carbon, mesocarbon microbeads (MCMB), Sn particles, SnO2, SnO, Li4Ti5O 12A group consisting of particles, Si particles, Si-C composite particles, and combinations thereof.

[0182] In certain embodiments, the core-shell composite material comprises a core containing a carbonaceous material and a shell coated on the core of the carbonaceous material. In some embodiments, the carbonaceous material is selected from the group consisting of soft carbon, hard carbon, natural graphite particles, synthetic graphite particles, mesocarbon microbeads, Kish graphite, pyrolytic carbon, mesophase pitch, mesophase pitch-based carbon fibers, and combinations thereof. In certain embodiments, the shell is selected from the group consisting of natural graphite particles, synthetic graphite particles, hard carbon, soft carbon, mesocarbon microbeads (MCMB), Sn particles, SnO2, SnO, Li4Ti5O 12 A group consisting of particles, Si particles, Si-C composite particles, and combinations thereof.

[0183] In certain embodiments, the anode active material is not doped with a metal element or a non-metal element. In some embodiments, the anode active material is not doped with Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, B, Si, Ge, N, P, F, S, Cl, I, or Se.

[0184] In some embodiments, the electrode layer may further comprise other additives for enhancing the electrode performance. In some embodiments, the additives may include a conductive agent, a surfactant, a dispersant, and a flexibility enhancing additive.

[0185] In some embodiments, the electrode layer further comprises a conductive agent. The conductive agent is used to enhance the electrical conductivity of the electrode. Any suitable material can be used as the conductive agent. In some embodiments, the conductive agent is a carbonaceous material. Some non-limiting examples include carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, carbon fibers, carbon nanofibers, graphitized carbon flakes, carbon nanotubes, activated carbon, Super P, 0-dimensional KS6, one-dimensional vapor-grown carbon fibers (VGCF), mesoporous carbon, and combinations thereof.

[0186] In some embodiments, the electrode layer further comprises a lithium salt. The lithium salt helps to increase the ionic conductivity of the electrode layer, thereby reducing the resistance of the electrode. In some embodiments, the lithium salt is selected from the group consisting of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium metaborate (LiBO2), lithium perchlorate (LiClO4), lithium nitrate (LiNO3), lithium bis(fluorosulfonyl)imide (LiFSI), lithium iodide (LiI), lithium tetrachloroaluminate (LiAlCl4), lithium difluoro(oxalato)borate (LiBF2C2O4), lithium bis(oxalato)borate (LiBOB), lithium acetate (LiAc), and combinations thereof.

[0187] In some embodiments, the electrode layer further comprises an ion-conductive polymer. The ion-conductive polymer helps increase the ionic conductivity of the electrode layer, thereby reducing the resistance of the electrode. In some embodiments, the ion-conductive polymer is selected from the group consisting of polyethers, polycarbonates, polyacrylates, polysiloxanes, polyphosphazenes, polyethylene derivatives, alkylene oxide derivatives, phosphate polymers, polylysine, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, polymers containing one or more dissociable groups, copolymers thereof, and combinations thereof. In some embodiments, the ion-conductive polymer is selected from the group consisting of polyacrylonitriles (PANs), poly(ethylene carbonate)s (PECs), polyacrylamides (PAMs), polyethylene glycols (PEGs), poly(ethylene oxide)s (PEOs), poly(2-hydroxyethyl methacrylate)s (P(HEMAs)), polyphosphonates (PPhs), polysiloxanes, polyamides (PAs), polylactones, polyesters, poly(phosphazene)s (PPHOSs), polyurethanes (PUs), copolymers thereof, and combinations thereof.

[0188] In some embodiments, the electrode layer further comprises an inorganic solid electrolyte. The inorganic solid electrolyte can help increase the ionic conductivity of the electrode layer, thereby reducing the resistance of the electrode. In some embodiments, the inorganic solid electrolyte is selected from LPS sulfides containing sulfur and phosphorus, such as Li2S-P2S5; Li 4-x Ge 1-x P x S4 (LGPS, where x is from 0.1 to 2); Li 10±1 MP2X 12 (M = Ge, Si, Sn, Al, X = S, Se); Li 3.833 Sn 0.833 As 0.166 S4; Li4SnS4; B2S3-Li2S; xLi2S-(100-x)P2S5 (x is from 70 to 80); Li2S-SiS2-Li3N; Li2S-P2S5-LiI; Li2S-SiS2-LiI; Li2S-B2S3-LiI; Li 10 SnP2S 12 ; Li6PS5X thiogermanate (where X is a halogen); thio-LISICON compounds, such as Li 3.25 Ge 0.25 P 0.75 S4; perovskite-like compounds, such as Li3SX (X is Cl or Br); lithium-phosphorus-iodine-oxygen sulfides; lithium-phosphorus-oxygen sulfides; lithium-zinc-germanium sulfides; lithium-germanium sulfides; LLTO-based compounds, such as (La, Li)TiO3; Li6La2CaTa6O 12 ; Li6La2ANb2O 12(A is Ca and / or Sr); Li2Nd3TeSbO 12 ; Li3BO 2.5 N 0.5 ; Li9SiAlO8; LAGP compounds (Li 1+x Al x Ge 2-x (PO4)3, where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1); Li2O - LATP compounds, such as Al2O3 - TiO2 - P2O5; Li 1+x Al x Ti 2-x (PO4)3 (where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1); Li 1+x Ti 2-x Al x Si y (PO4) 3-y (where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1); LiAl x Zr 2-x (PO4)3 (where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1); LiTi x Zr 2-x (PO4)3 (where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1); LISICON - type solid electrolytes; LIPON compounds (Li 3+ y PO 4-x N x , where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1); perovskite compounds ((La, Li)TiO3); NASICON compounds, such as LiTi2(PO4)3; inverse perovskites, such as Li3OX (X is Cl or Br); lithium - aluminum - titanium - silicon - phosphate (LATSP); lithium - aluminum oxides; lithium - vanadium - germanium oxides; lithium - zinc - germanium oxides; lithium - filled garnets, such as lithium - lanthanum - zirconium oxides; lithium - lanthanum - zirconium - aluminum oxides; lithium - lanthanum - zirconium - tantalum oxides; Li3N; lithium - aluminum chlorides and combinations thereof.

[0189] The copolymer binder used in the present invention exhibits strong adhesion to the current collector. It is important for the copolymer binder to have good adhesion strength to the current collector because it promotes the adhesion of the electrode layer to the current collector in the manufacture of battery electrodes, prevents electrode separation, and enhances its mechanical stability. In some embodiments, the adhesion strength between the copolymer binder and the current collector is from about 2 N / cm to about 6 N / cm, from about 2 N / cm to about 5.8 N / cm, from about 2 N / cm to about 5.6 N / cm, from about 2 N / cm to about 5.4 N / cm, from about 2 N / cm to about 5.2 N / cm, from about 2 N / cm to about 5 N / cm, from about 2 N / cm to about 4.8 N / cm, from about 2 N / cm to about 4.6 N / cm, from about 2 N / cm to about 4.4 N / cm, from about 2 N / cm to about 4.2 N / cm, from about 2 N / cm to about 4 N / cm, from about 2 N / cm to about 3.9 N / cm, from about 2 N / cm to about 3.8 N / cm, from about 2 N / cm to about 3.7 N / cm, from about 2 N / cm to about 3.6 N / cm, from about 2 N / cm to about 3.5 N / cm, from about 2 N / cm to about 3.4 N / cm, from about 2 N / cm to about 3.3 N / cm, from about 2 N / cm to about 3.2 N / cm, from about 2 N / cm to about 3.1 N / cm, from about 2 N / cm to about 3 N / cm, from about 2.1 N / cm to about 6 N / cm, from about 2.2 N / cm to about 6 N / cm, from about 2.3 N / cm to about 6 N / cm, from about 2.4 N / cm to about 6 N / cm, from about 2.5 N / cm to about 6 N / cm, from about 2.6 N / cm to about 6 N / cm, from about 2.7 N / cm to about 6 N / cm, from about 2.8 N / cm to about 6 N / cm, from about 2.9 N / cm to about 6 N / cm, from about 3 N / cm to about 6 N / cm, from about 3.1 N / cm to about 6 N / cm, from about 3.2 N / cm to about 6 N / cm, from about 3.3 N / cm to about 6 N / cm, from about 3.4 N / cm to about 6 N / cm, from about 3.5 N / cm to about 6 N / cm, from about 3.6 N / cm to about 6 N / cm, from about 3.7 N / cm to about 6 N / cm, from about 3.8 N / cm to about 6 N / cm, from about 3.9 N / cm to about 6 N / cm, from about 4 N / cm to about 6 N / cm, from about 2.5 N / cm to about 5.5 N / cm, from about 2.5 N / cm to about 5 N / cm, from about 2.5 N / cm to about 4.5 N / cm, from about 2.5 N / cm to about 4 N / cm, from about 2.5 N / cm to about 3.5 N / cm, from about 3 N / cm to about 5 N / cm, from about 2.2 N / cm to about 4.2 N / cm or from about 2.2 N / cm to about 5.2 N / cm.

[0190] In some embodiments, the adhesion strength between the copolymer binder and the current collector is less than 6 N / cm, less than 5.8 N / cm, less than 5.6 N / cm, less than 5.4 N / cm, less than 5.2 N / cm, less than 5 N / cm, less than 4.8 N / cm, less than 4.6 N / cm, less than 4.4 N / cm, less than 4.2 N / cm, less than 4 N / cm, less than 3.9 N / cm, less than 3.8 N / cm, less than 3.7 N / cm, less than 3.6 N / cm, less than 3.5 N / cm, less than 3.4 N / cm, less than 3.3 N / cm, less than 3.2 N / cm, less than 3.1 N / cm, less than 3 N / cm, less than 2.9 N / cm, less than 2.8 N / cm, less than 2.7 N / cm, less than 2.6 N / cm, less than 2.5 N / cm, less than 2.4 N / cm, less than 2.3 N / cm or less than 2.2 N / cm. In some embodiments, the adhesion strength between the copolymer binder and the current collector is greater than 2 N / cm, greater than 2.1 N / cm, greater than 2.2 N / cm, greater than 2.3 N / cm, greater than 2.4 N / cm, greater than 2.5 N / cm, greater than 2.6 N / cm, greater than 2.7 N / cm, greater than 2.8 N / cm, greater than 2.9 N / cm, greater than 3 N / cm, greater than 3.1 N / cm, greater than 3.2 N / cm, greater than 3.3 N / cm, greater than 3.4 N / cm, greater than 3.5 N / cm, greater than 3.6 N / cm, greater than 3.7 N / cm, greater than 3.8 N / cm, greater than 3.9 N / cm, greater than 4 N / cm, greater than 4.2 N / cm, greater than 4.4 N / cm, greater than 4.6 N / cm, greater than 4.8 N / cm, greater than 5 N / cm, greater than 5.2 N / cm, greater than 5.4 N / cm, greater than 5.6 N / cm or greater than 5.8 N / cm.

[0191] In addition, the copolymer binder applied in the present invention can exhibit strong adhesion of the electrode layer to the current collector in the electrode. It is important for the electrode layer to have good peel strength with respect to the current collector because this will greatly affect the mechanical stability of the electrode and the cyclability of the battery. Therefore, the electrode should have sufficient peel strength to withstand the rigors of the battery manufacturing process.

[0192] In some embodiments, the peel strength between the current collector and the electrode layer is in the range of about 1.0 N / cm to about 8.0 N / cm, about 1.0 N / cm to about 6.0 N / cm, about 1.0 N / cm to about 5.0 N / cm, about 1.0 N / cm to about 4.0 N / cm, about 1.0 N / cm to about 3.0 N / cm, about 1.0 N / cm to about 2.5 N / cm, about 1.0 N / cm to about 2.0 N / cm, about 1.2 N / cm to about 3.0 N / cm, about 1.2 N / cm to about 2.5 N / cm, about 1.2 N / cm to about 2.0 N / cm, about 1.5 N / cm to about 3.0 N / cm, about 1.5 N / cm to about 2.5 N / cm, about 1.5 N / cm to about 2.0 N / cm, about 1.8 N / cm to about 3.0 N / cm, about 1.8 N / cm to about 2.5 N / cm, about 2.0 N / cm to about 6.0 N / cm, about 2.0 N / cm to about 5.0 N / cm, about 2.0 N / cm to about 3.0 N / cm, about 2.0 N / cm to about 2.5 N / cm, about 2.2 N / cm to about 3.0 N / cm, about 2.5 N / cm to about 3.0 N / cm, about 3.0 N / cm to about 8.0 N / cm, about 3.0 N / cm to about 6.0 N / cm, or about 4.0 N / cm to about 6.0 N / cm.

[0193] In some embodiments, the peel strength between the current collector and the electrode layer is 1.0 N / cm or higher, 1.2 N / cm or higher, 1.5 N / cm or higher, 2.0 N / cm or higher, 2.2 N / cm or higher, 2.5 N / cm or higher, 3.0 N / cm or higher, 3.5 N / cm or higher, 4.5 N / cm or higher, 5.0 N / cm or higher, 5.5 N / cm or higher, 6.0 N / cm or higher, 6.5 N / cm or higher, 7.0 N / cm or higher, or 7.5 N / cm or higher. In some embodiments, the peel strength between the current collector and the electrode layer is less than 8.0 N / cm, less than 7.5 N / cm, less than 7.0 N / cm, less than 6.5 N / cm, less than 6.0 N / cm, less than 5.5 N / cm, less than 5.0 N / cm, less than 4.5 N / cm, less than 4.0 N / cm, less than 3.5 N / cm, less than 3.0 N / cm, less than 2.8 N / cm, less than 2.5 N / cm, less than 2.2 N / cm, less than 2.0 N / cm, less than 1.8 N / cm, or less than 1.5 N / cm.

[0194] In some embodiments, the surface density of each of the cathode electrode layer and the anode electrode layer is independently about 1 mg / cm 2 to about 50 mg / cm 2 、about 2.5 mg / cm 2 to about 50 mg / cm2 , about 5 mg / cm 2 to about 50 mg / cm 2 , about 7.5 mg / cm 2 to about 50 mg / cm 2 , about 10 mg / cm 2 to about 50 mg / cm 2 , about 12.5 mg / cm 2 to about 50 mg / cm 2 , about 15 mg / cm 2 to about 50 mg / cm 2 , about 17.5 mg / cm 2 to about 50 mg / cm 2 , about 20 mg / cm 2 to about 50 mg / cm 2 , about 25 mg / cm 2 to about 50 mg / cm 2 , about 30 mg / cm 2 to about 50 mg / cm 2 , about 1 mg / cm 2 to about 30 mg / cm 2 , about 2.5 mg / cm 2 to about 30 mg / cm 2 , about 5 mg / cm 2 to about 30 mg / cm 2 , about 7.5 mg / cm 2 to about 30 mg / cm 2 , about 10 mg / cm 2 to about 30 mg / cm 2 , about 12.5 mg / cm 2 to about 30 mg / cm 2 , about 15 mg / cm 2 to about 30 mg / cm 2 , about 17.5 mg / cm 2 to about 30 mg / cm 2 , about 20 mg / cm 2 to about 30 mg / cm 2 , about 1 mg / cm 2 to about 20 mg / cm 2 , about 2.5 mg / cm 2 to about 20 mg / cm 2 , about 5 mg / cm 2 to about 20 mg / cm 2 , about 7.5 mg / cm 2 to about 20 mg / cm 2 , about 10 mg / cm2 to about 20 mg / cm 2 、about 12.5 mg / cm 2 to about 20 mg / cm 2 、about 1 mg / cm 2 to about 15 mg / cm 2 、about 2.5 mg / cm 2 to about 15 mg / cm 2 、about 5 mg / cm 2 to about 15 mg / cm 2 、about 7.5 mg / cm 2 to about 15 mg / cm 2 or about 10 mg / cm 2 to about 15 mg / cm 2 。

[0195] In some embodiments, the surface density of each of the cathode electrode layer and the anode electrode layer is independently less than 50 mg / cm 2 、less than 45 mg / cm 2 、less than 35 mg / cm 2 、less than 30 mg / cm 2 、less than 25 mg / cm 2 、less than 20 mg / cm 2 、less than 17.5 mg / cm 2 、less than 15 mg / cm 2 、less than 12.5 mg / cm 2 、less than 10 mg / cm 2 、less than 7.5 mg / cm 2 、less than 5 mg / cm 2 or less than 2.5 mg / cm 2 。In some embodiments, the surface density of each of the cathode electrode layer and the anode electrode layer is independently greater than 1 mg / cm 2 、greater than 2.5 mg / cm 2 、greater than 5 mg / cm 2 、greater than 7.5 mg / cm 2 、greater than 10 mg / cm 2 、greater than 12.5 mg / cm 2 、greater than 15 mg / cm 2 、greater than 17.5 mg / cm 2 、greater than 20 mg / cm 2 、greater than 25 mg / cm 2 、greater than 30 mg / cm 2 、greater than 35 mg / cm 2 or greater than 40 mg / cm 2 。

[0196] In some embodiments, the density of each of the cathode electrode layer and the anode electrode layer is independently about 0.5 g / cm 3 to about 7.5 g / cm 3 、about 1 g / cm 3 to about 7.5 g / cm 3 、about 1.5 g / cm 3 to about 7.5 g / cm 3 、about 2 g / cm 3 to about 7.5 g / cm 3 、about 2.5 g / cm 3 to about 7.5 g / cm 3 、about 3 g / cm 3 to about 7.5 g / cm 3 、about 3.5 g / cm 3 to about 7.5 g / cm 3 、about 4 g / cm 3 to about 7.5 g / cm 3 、about 4.5 g / cm 3 to about 7.5 g / cm 3 、about 5 g / cm 3 to about 7.5 g / cm 3 、about 0.5 g / cm 3 to about 5 g / cm 3 、about 1 g / cm 3 to about 5 g / cm 3 、about 1.5 g / cm 3 to about 5 g / cm 3 、about 2 g / cm 3 to about 5 g / cm 3 、about 2.5 g / cm 3 to about 5 g / cm 3 、about 3 g / cm 3 to about 5 g / cm 3 、about 0.5 g / cm 3 to about 2.5 g / cm 3 、about 1 g / cm 3 to about 2.5 g / cm 3 or about 1.5 g / cm 3 to about 2.5 g / cm 3 。

[0197] In some embodiments, the density of each of the cathode electrode layer and the anode electrode layer is independently less than 7.5 g / cm 3 、less than 7 g / cm 3 、less than 6.5 g / cm 3 、less than 6 g / cm3 , less than 5.5 g / cm 3 , less than 5 g / cm 3 , less than 4.5 g / cm 3 , less than 4 g / cm 3 , less than 3.5 g / cm 3 , less than 3 g / cm 3 , less than 2.5 g / cm 3 , less than 2 g / cm 3 or less than 1.5 g / cm 3 . In some embodiments, the density of each of the cathode electrode layer and the anode electrode layer is independently greater than 0.5 g / cm 3 , greater than 1 g / cm 3 , greater than 1.5 g / cm 3 , greater than 2 g / cm 3 , greater than 2.5 g / cm 3 , greater than 3 g / cm 3 , greater than 3.5 g / cm 3 , greater than 4 g / cm 3 , greater than 4.5 g / cm 3 , greater than 5 g / cm 3 , greater than 5.5 g / cm 3 , greater than 6 g / cm 3 or greater than 6.5 g / cm 3 .

[0198] In some embodiments, a battery containing an electrode to be stripped is first disassembled into one or more battery fragments, wherein the one or more battery fragments contain one or more electrode fragments. There is no particular limitation on the method for disassembling the battery, except that the minimum size of the resulting battery fragments should be greater than the mesh size of the sieve used to screen the complex-stripping solution mixture after stripping, to ensure that these fragments can be screened. In some embodiments, a crusher, a grinder or a cutter is used to disassemble the battery. In some embodiments, a water jet is used to disassemble the battery. In some embodiments, the battery is cryogenically treated before disassembly, such as using liquid nitrogen. In some embodiments, the battery is first discharged. In some embodiments, the battery is discharged by immersion in a salt solution. In other embodiments, when a water jet is used to disassemble the battery, and / or when the battery is cryogenically treated before disassembly, it is not necessary to discharge the battery.

[0199] In some embodiments, when immersing battery debris in a stripping solution to effect stripping of the electrodes, the weight ratio of the battery debris to the stripping solution is from about 0.01% to about 50%, from about 0.02% to about 50%, from about 0.05% to about 50%, from about 0.1% to about 50%, from about 0.2% to about 50%, from about 0.5% to about 50%, from about 1% to about 50%, from about 2% to about 50%, from about 5% to about 50%, from about 10% to about 50%, from about 15% to about 50%, from about 20% to about 50%, from about 25% to about 50%, from about 30% to about 50%, from about 0.01% to about 25%, from about 0.02% to about 25%, from about 0.05% to about 25%, from about 0.1% to about 25%, from about 0.2% to about 25%, from about 0.5% to about 25%, from about 1% to about 25%, from about 2% to about 25%, from about 5% to about 25%, from about 10% to about 25%, from about 0.1% to about 15%, from about 0.2% to about 15%, from about 0.5% to about 15%, from about 1% to about 15%, from about 2% to about 15%, from about 5% to about 15%, from about 0.1% to about 5%, from about 0.2% to about 5%, from about 0.5% to about 5%, from about 1% to about 5%, or from about 2% to about 5%.

[0200] In some embodiments, when immersing battery debris in a stripping solution to effect stripping of the electrodes, the weight ratio of the battery debris to the stripping solution is less than 50%, less than 45%, less than 40%, less than 35%, less than 30%, less than 25%, less than 20%, less than 15%, less than 10%, less than 5%, less than 2%, less than 1%, less than 0.5%, less than 0.2%, less than 0.1%, or less than 0.05%. In some embodiments, when immersing battery debris in a stripping solution to effect stripping of the electrodes, the weight ratio of the battery debris to the stripping solution is greater than 0.01%, greater than 0.02%, greater than 0.05%, greater than 0.1%, greater than 0.2%, greater than 0.5%, greater than 1%, greater than 2%, greater than 5%, greater than 10%, greater than 15%, greater than 20%, greater than 25%, greater than 30%, greater than 35%, or greater than 40%.

[0201] In other embodiments, after disassembly but before stripping, the electrode debris is separated from the remaining battery debris. In some embodiments, after the electrode debris is separated from the remaining battery debris, only the electrode debris is stripped.

[0202] In some embodiments, when only the electrode fragments are immersed in the stripping solution to effect stripping of the electrodes, the weight ratio of the electrode fragments to the stripping solution is from about 0.01% to about 50%, from about 0.02% to about 50%, from about 0.05% to about 50%, from about 0.1% to about 50%, from about 0.2% to about 50%, from about 0.5% to about 50%, from about 1% to about 50%, from about 2% to about 50%, from about 5% to about 50%, from about 10% to about 50%, from about 15% to about 50%, from about 20% to about 50%, from about 25% to about 50%, from about 30% to about 50%, from about 0.01% to about 25%, from about 0.02% to about 25%, from about 0.05% to about 25%, from about 0.1% to about 25%, from about 0.2% to about 25%, from about 0.5% to about 25%, from about 1% to about 25%, from about 2% to about 25%, from about 5% to about 25%, from about 10% to about 25%, from about 0.1% to about 15%, from about 0.2% to about 15%, from about 0.5% to about 15%, from about 1% to about 15%, from about 2% to about 15%, from about 5% to about 15%, from about 0.1% to about 5%, from about 0.2% to about 5%, from about 0.5% to about 5%, from about 1% to about 5% or from about 2% to about 5%.

[0203] In some embodiments, when only the electrode fragments are immersed in the stripping solution to effect stripping of the electrodes, the weight ratio of the electrode fragments to the stripping solution is less than 50%, less than 45%, less than 40%, less than 35%, less than 30%, less than 25%, less than 20%, less than 15%, less than 10%, less than 5%, less than 2%, less than 1%, less than 0.5%, less than 0.2%, less than 0.1% or less than 0.05%. In some embodiments, when only the electrode fragments are immersed in the stripping solution to effect stripping of the electrodes, the weight ratio of the electrode fragments to the stripping solution is greater than 0.01%, greater than 0.02%, greater than 0.05%, greater than 0.1%, greater than 0.2%, greater than 0.5%, greater than 1%, greater than 2%, greater than 5%, greater than 10%, greater than 15%, greater than 20%, greater than 25%, greater than 30%, greater than 35% or greater than 40%.

[0204] The stripping success rate of stripping the electrodes containing the copolymer binder by the method of the present invention is greater than 75%, the recovery rate is extremely high (>97%), and the electrodes are stripped from the current collector within a short time (<180 s).

[0205] In some embodiments, the stripping of the electrodes occurs at the electrode layer-current collector interface. The stripping success rate refers to the degree of stripping of the electrode layer from the current collector. The success rate can be calculated by the formula:

[0206]

[0207] After the stripping reaction, the weight of the electrode layer present in the stripping solution will be equivalent to the weight of the successfully stripped electrode layer. The weight of the electrode layer still coated on the current collector is the weight of the electrode layer remaining on the current collector, and can be measured by manually scraping off the remaining electrode layer and then weighing the scraped portion. In the present invention, when the electrode layer is completely stripped from the current collector, the stripping success rate is 100%. In other cases where the electrode layer is not stripped from the current collector or the electrode layer is partially stripped from the current collector and there are still visible adherents of the electrode layer remaining on the current collector, the success rate will be less than 100%.

[0208] The recovery rate refers to the proportion of the sum of the weights of the successfully extracted and recovered electrode layer and the current collector, based on the initial weight of the electrode before immersion in the stripping solution. The recovery rate is only calculated when the success rate is greater than 75%, because below this value, the stripping is considered ineffective and economically unfeasible, and thus not worthy of consideration for application in industrial production. It reflects the degree of corrosion of the useful metal materials in the electrode and / or the degree of dissolution of the useful metal materials in the stripping solution. The method disclosed herein achieves a high recovery rate, indicating that the degree of corrosion or dissolution of the metal electrode material (such as the current collector) immersed in the stripping solution can be negligible.

[0209] Considering the composition of the copolymer binder used, the present invention provides a simple method for stripping the electrode layer from the current collector. Since the separation of the electrode layer and the current collector is a key step in battery recycling, the method disclosed herein provides a technical solution that meets the requirements of battery recycling. The method of the present invention avoids both complex separation processes and contamination of the current collector, and achieves excellent material recovery (i.e., high recovery rate).

[0210] The method disclosed in the present invention significantly reduces the time required for the electrode layer in the battery to be stripped from the current collector without damaging the underlying current collector. In the case of a short contact time between the electrode and the stripping solution, corrosion of the current collector, the electrode active material, and other electrode materials made of metal can be avoided. For example, when an electrode containing an aluminum current collector is immersed in a stripping solution containing a strong base, the short contact time causes the natural oxide layer formed on the surface of the aluminum current collector to achieve an anti-corrosion protection effect sufficient for protection.

[0211] The method of the present invention can also be used to achieve the stripping of the packaging material by immersing the packaging material in the stripping solution; wherein the packaging material comprises a metal and a coating applied to one or both sides of the metal, and the coating comprises a copolymer binder.

[0212] The coating can include metal, plastic, paper or possibly cardboard. By treating the packaging material with a stripping solution containing strong base, the metal and the coating are separated from each other. The method disclosed herein can be used for stripping various packaging materials, especially in food packaging and beverage packaging, to achieve the recycling and reuse of each material component used in the packaging.

[0213] The following examples are given to illustrate embodiments of the invention and are not intended to limit the invention to the specific embodiments recited. Unless otherwise indicated, all parts and percentages are by weight. All numerical values are approximate. When a numerical range is given, it should be understood that embodiments outside the stated range still fall within the scope of the invention. The specific details described in each example should not be construed as essential features of the invention.

[0214] Example

[0215] The pH value of the electrode-stripping solution mixture after stripping was measured by an electrode-type pH meter (ION 2700, Eutech Instruments).

[0216] The recovery rate refers to the proportion of the sum of the weights of the recovered electrode layer and the current collector based on the initial weight of the electrode before immersion in the stripping solution.

[0217] The stripping success rate refers to the degree to which the electrode layer is stripped from the current collector. It can be calculated by the formula:

[0218]

[0219] Therefore, after the stripping reaction is completed or terminated, the electrode layer in the stripping solution is recovered to obtain the weight of the successfully stripped electrode layer, while the remaining electrode layer material (if any) on the electrode is manually scraped to obtain the weight of the electrode layer remaining on the current collector.

[0220] The adhesion strength of the dried adhesive layer was measured by a tensile tester (DZ-106A, from Dongguan Zonhow Test Equipment Co., Ltd., China). This test measures the average force in Newtons required to strip the adhesive layer from the current collector at a 180° angle. The average roughness depth (R z) is 2 μm. The copolymer binder is coated on the current collector and dried to obtain a binder layer with a thickness of 10 μm to 12 μm. Then, the coated current collector is placed in an environment with a constant temperature of 25 °C and a humidity of 50% to 60% for 30 minutes. A tape 18 mm wide and 20 mm long (3M; USA; model 810) is adhered to the surface of the binder layer. The binder strip is clamped on the testing machine, and then the tape is folded backward at 180°, then placed in the movable jaws, and pulled at a peeling speed of 300 mm / minute at room temperature. The measured maximum peeling force is used as the adhesion strength. The measurement is repeated 3 times and the average value is taken.

[0221] The peeling strength of the dried electrode layer is measured by a tensile tester (DZ-106A, from Dongguan Zonhow Test Equipment Co., Ltd., China). This test measures the average force in Newtons required to peel the electrode layer from the current collector at a 180° angle. The average roughness depth (R z ) is 2 μm. A tape 18 mm wide and 20 mm long (3M; USA; model 810) is adhered to the surface of the cathode electrode layer. The cathode strip is clamped on the testing machine, and then the tape is folded backward at 180°, then placed in the movable jaws, and pulled at a peeling speed of 200 mm / minute at room temperature. The measured maximum peeling force is used as the peeling strength. The measurement is repeated 3 times and the average value is taken.

[0222] Example 1

[0223] Assembly of a pouch-type lithium-ion full cell

[0224] A) Preparation of a polymer binder

[0225] 7.45 g of sodium hydroxide (NaOH) is added to a round-bottom flask containing 380 g of distilled water. The mixture is stirred at 80 rpm for 30 minutes to obtain a first suspension.

[0226] 16.77 g of acrylic acid is added to the first suspension. The mixture is further stirred at 80 rpm for 30 minutes to obtain a second suspension.

[0227] 7.19 g of acrylamide is dissolved in 10 g of deionized water to form an acrylamide solution. Thereafter, 17.19 g of the acrylamide solution is added to the second suspension. The mixture is further heated to 55 °C and stirred at 80 rpm for 45 minutes to obtain a third suspension.

[0228] 35.95 g of acrylonitrile is added to the third suspension. The mixture is further stirred at 80 rpm for 10 minutes to obtain a fourth suspension.

[0229] After that, 0.015 g of a water-soluble free radical initiator (ammonium persulfate, APS; obtained from Aladdin Industrial Corporation, China) was dissolved in 3 g of deionized water, and 0.0075 g of a reducing agent (sodium bisulfite; obtained from Tianjin Damao Chemical Reagent Factory, China) was dissolved in 1.5 g of deionized water. 3.015 g of the APS solution and 1.5075 g of the sodium bisulfite solution were added to the fourth suspension. The mixture was stirred at 200 rpm at 55 °C for 24 h to obtain a fifth suspension.

[0230] After complete reaction, the temperature of the fifth suspension was lowered to 25 °C. 3.72 g of NaOH was dissolved in 400 g of deionized water. Thereafter, 403.72 g of the sodium hydroxide solution was added dropwise to the fifth suspension to adjust the pH to 7.3 to form a sixth suspension. The sixth suspension was filtered using a 200-μm nylon mesh to form a binder material. The solid content of the binder material was 8.88 wt.%. The adhesion strength between the copolymer binder and the current collector was 3.41 N / cm. The components of the copolymer binder of Example 1 and their respective ratios are shown in Table 1 below.

[0231] B) Preparation of a positive electrode

[0232] 12 g of a conductive agent (Super P; obtained from Timcal Ltd, Bodio, Switzerland) and 100 g of the binder material (solid content of 8.88 wt.%) were dispersed in 74 g of deionized water while being stirred with an overhead stirrer (R20, IKA) to prepare a first mixture. After addition, the first mixture was further stirred at 1200 rpm at 25 °C for about 30 min.

[0233] Thereafter, at 25 °C, 276 g of NMC532 (purchased from Shandong Tianjiao New Energy Co., Ltd., China) was added to the first mixture while being stirred with an overhead stirrer to prepare a second mixture. Then, the second mixture was degassed at a pressure of about 10 kPa for 1 h. Then, the second mixture was further stirred at 1200 rpm at 25 °C for about 60 min to form a homogenized cathode slurry.

[0234] The homogenized cathode slurry was coated onto both sides of a 16-μm-thick aluminum foil serving as a current collector using a blade coater with a gap width of 120 μm. The 80-μm-thick coated slurry on the aluminum foil was dried in an electrically heated oven at 85 °C to form a cathode electrode layer. The drying time was about 120 min. Then the electrode was pressed to reduce the thickness of the cathode electrode layer to 34 μm. The surface density of the cathode electrode layer on the current collector was 16.00 mg / cm 2 。

[0235] C) Preparation of a negative electrode

[0236] Mix 93 wt.% of graphite (BTR New Energy Materials Inc., Shenzhen, Guangdong, China) with 1 wt.% of carboxymethyl cellulose (CMC, BSH-12, DKS Co., Ltd., Japan) as a binder, 3 wt.% of SBR (AL-2001, NIPPON A&L Co., Japan), and 3 wt.% of carbon black as a conductive agent in deionized water to prepare the negative electrode slurry. The solid content of the anode slurry is 51.5 wt.%. The slurry is coated on both sides of a copper foil with a thickness of 8 μm using a knife coater with a gap width of approximately 120 μm. The coated slurry on the copper foil is dried at approximately 85 °C for 120 minutes using a hot air dryer to obtain the negative electrode. Then, the electrode is pressed to reduce the thickness of the anode electrode layer to 60 μm, and the surface density of the anode electrode layer is 10 mg / cm 2 。

[0237] D) Assembly of a pouch-type cell

[0238] After drying, the obtained cathode coating and anode coating are respectively cut into rectangular pieces with dimensions of 5.2 cm × 8.5 cm and 5.4 cm × 8.7 cm for preparing cathode sheets and anode sheets respectively. A soft-pack battery is prepared by alternately stacking the cathode and anode sheets and separating them with a porous polyethylene separator (Celgard, LLC, USA) with a thickness of 25 μm. The electrolyte is a solution containing LiPF6 (1 M) in a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) with a volume ratio of 1:1:1. The battery is assembled in a high-purity argon environment with a moisture and oxygen content < 1 ppm. After injecting the electrolyte, the soft-pack Formula battery is vacuum-sealed and then mechanically pressed using a stamping tool with a standard shape.

[0239] Then, the assembled soft-pack battery is subjected to repeated charge and discharge cycles between 3.0 V and 4.2 V at a constant current rate of 1C to simulate the real usage mode. The actual battery capacity is approximately 5 Ah. After 800 cycles, the nominal capacity drops below 80% of its initial rated capacity.

[0240] Recovery of the battery

[0241] A) Discharge and disassembly of a pouch-type cell

[0242] Fully discharge the used lithium-ion battery (0.5 kg) by soaking it in 6% NaCl solution for 12 hours. After discharging, mechanically disassemble the lithium-ion battery using a cutting machine to recover the electrodes. Cut the electrodes into small pieces with an average length of approximately 2 cm to approximately 4 cm.

[0243] B) Preparation of a stripping solution

[0244] 14.00 g of anhydrous sodium hydroxide (Sigma - Aldrich, USA) was added to 1000 g of deionized water to form a stripping solution with a concentration of 0.35 M.

[0245] C) Immersion of the cathode in the stripping solution

[0246] 5.07 g of the cathode was placed in a container filled with 1000 g of the stripping solution heated to 25 °C. The cathode layer was separated from the aluminum foil. Once it was observed that the cathode layer had been stripped, the stripping solution containing sodium hydroxide and deionized water was removed by passing it through a sieve with a mesh width of 4 mm to recover the cathode layer and the aluminum foil. The stripping solution could be further reused for stripping electrodes. Under atmospheric pressure, the recovered cathode layer and aluminum foil were dried in an oven at 80 °C for 5 hours, and the recovery rate was 99.40%. The stripping success rate and recovery rate of the stripped cathode material were measured and described in Table 1 below.

[0247] Assembly of the pouch-type lithium-ion full cells of Examples 2-5

[0248] A soft - package lithium - ion battery was prepared by the method described in Example 1. Then the assembled soft - package battery was cycled repeatedly in the same manner as in Example 1.

[0249] Recovery of the battery of Example 2

[0250] A) Discharge and disassembly of a pouch-type cell

[0251] The used lithium - ion battery was discharged and disassembled by the same method described in Example 1.

[0252] B) Preparation of a stripping solution

[0253] 20.0 g of anhydrous sodium hydroxide (Sigma - Aldrich, USA) was added to 1000 g of deionized water to form a stripping solution with a concentration of 0.50 M.

[0254] C) Immersion of the cathode in the stripping solution

[0255] The cathode was immersed and stripped by the method described in Example 1, except that the above - mentioned stripping solution was used. The stripping success rate and recovery rate of the stripped cathode material were measured and described in Table 1 below.

[0256] Recovery of the battery of Example 3

[0257] A) Discharge and disassembly of a pouch-type cell

[0258] Discharge and disassemble the used lithium-ion batteries by the same method described in Example 1.

[0259] B) Preparation of a stripping solution

[0260] Add 30.0 g of anhydrous sodium hydroxide (Sigma-Aldrich, USA) to 1000 g of deionized water to form a stripping solution with a concentration of 0.75 M.

[0261] C) Immersion of the cathode in the stripping solution

[0262] Immerse and strip the cathode by the method described in Example 1, except that the above-mentioned stripping solution is used. Measure the stripping success rate and recovery rate of the stripped cathode material and present them in Table 1 below.

[0263] Recovery of the battery of Example 4

[0264] A) Discharge and disassembly of a pouch-type cell

[0265] Discharge and disassemble the used lithium-ion batteries by the same method described in Example 1.

[0266] B) Preparation of a stripping solution

[0267] Add 40.0 g of anhydrous sodium hydroxide (Sigma-Aldrich, USA) to 1000 g of deionized water to form a stripping solution with a concentration of 1.0 M.

[0268] C) Immersion of the cathode in the stripping solution

[0269] Immerse and strip the cathode by the method described in Example 1, except that the above-mentioned stripping solution is used. Measure the stripping success rate and recovery rate of the stripped cathode material and present them in Table 1 below.

[0270] Recovery of the battery of Example 5

[0271] A) Discharge and disassembly of a pouch-type cell

[0272] Discharge and disassemble the used lithium-ion batteries by the same method described in Example 1.

[0273] B) Preparation of a stripping solution

[0274] Add 80.0 g of anhydrous sodium hydroxide (Sigma-Aldrich, USA) to 1000 g of deionized water to form a stripping solution with a concentration of 2.0 M.

[0275] C) Immersion of the cathode in the stripping solution

[0276] The cathode was immersed and stripped by the method described in Example 1, except that the above stripping solution was used. The stripping success rate and recovery rate of the stripped cathode material were measured and are shown in Table 1 below.

[0277] Assembly of the pouch-type lithium-ion full cells of Examples 6-7

[0278] A soft-pack lithium-ion battery was prepared by the method described in Example 4. Then, the assembled soft-pack battery was subjected to repeated cycling in the same manner as in Example 4.

[0279] Recovery of the battery of Example 6

[0280] The battery was recycled in the same manner as in Example 4, except that the stripping solution was heated to 70 °C. The stripping success rate and recovery rate of the stripped cathode material were measured and are shown in Table 1 below.

[0281] Recovery of the battery of Example 7

[0282] The battery was recycled in the same manner as in Example 4, except that the stripping solution was heated to 90 °C. The stripping success rate and recovery rate of the stripped cathode material were measured and are shown in Table 1 below.

[0283] Preparation of the polymer binder of Example 8

[0284] 8.25 g of sodium hydroxide (NaOH) was added to a round-bottom flask containing 380 g of distilled water. The mixture was stirred at 80 rpm for 30 minutes to obtain a first suspension.

[0285] 18.22 g of acrylic acid was added to the first suspension. The mixture was further stirred at 80 rpm for 30 minutes to obtain a second suspension.

[0286] 5.75 g of acrylamide was dissolved in 10 g of deionized water to form an acrylamide solution. Thereafter, 15.75 g of the acrylamide solution was added to the second suspension. The mixture was further heated to 55 °C and stirred at 80 rpm for 45 minutes to obtain a third suspension.

[0287] 35.96 g of acrylonitrile was added to the third suspension. The mixture was further stirred at 80 rpm for 10 minutes to obtain a fourth suspension.

[0288] In addition, 0.015 g of a water-soluble free radical initiator (ammonium persulfate, APS; purchased from Aladdin Industrial Corporation, China) was dissolved in 3 g of deionized water, and 0.0075 g of a reducing agent (sodium bisulfite; purchased from Tianjin Damao Chemical Reagent Factory, China) was dissolved in 1.5 g of deionized water. 3.015 g of the APS solution and 1.5075 g of the sodium bisulfite solution were added to the fourth suspension. The mixture was stirred at 200 rpm at 55 °C for 24 hours to obtain a fifth suspension.

[0289] After complete reaction, the temperature of the fifth suspension was lowered to 25 °C. 3.72 g of NaOH was dissolved in 400 g of deionized water. Thereafter, 403.72 g of the sodium hydroxide solution was added dropwise to the fifth suspension to adjust the pH to 7.3 to form a sixth suspension. The sixth suspension was filtered through a 200-μm nylon mesh to form a binder material. The components of the copolymer binder of Example 8 and their respective ratios are illustrated in Table 1 below.

[0290] Preparation of the polymer binder of Example 9

[0291] 5.42 g of sodium hydroxide (NaOH) was added to a round-bottom flask containing 380 g of distilled water. The mixture was stirred at 80 rpm for 30 minutes to obtain a first suspension.

[0292] 13.12 g of acrylic acid was added to the first suspension. The mixture was further stirred at 80 rpm for 30 minutes to obtain a second suspension.

[0293] 12.94 g of acrylamide was dissolved in 10 g of deionized water to form an acrylamide solution. Thereafter, 22.94 g of the acrylamide solution was added to the second suspension. The mixture was further heated to 55 °C and stirred at 80 rpm for 45 minutes to obtain a third suspension.

[0294] 34.35 g of acrylonitrile was added to the third suspension. The mixture was further stirred at 80 rpm for 10 minutes to obtain a fourth suspension.

[0295] In addition, 0.015 g of a water-soluble free radical initiator (ammonium persulfate, APS; purchased from Aladdin Industrial Corporation, China) was dissolved in 3 g of deionized water, and 0.0075 g of a reducing agent (sodium bisulfite; purchased from Tianjin Damao Chemical Reagent Factory, China) was dissolved in 1.5 g of deionized water. 3.015 g of the APS solution and 1.5075 g of the sodium bisulfite solution were added to the fourth suspension. The mixture was stirred at 200 rpm at 55 °C for 24 hours to obtain a fifth suspension.

[0296] After complete reaction, the temperature of the fifth suspension was lowered to 25 °C. 3.72 g of NaOH was dissolved in 400 g of deionized water. Thereafter, 403.72 g of the sodium hydroxide solution was added dropwise to the fifth suspension to adjust the pH to 7.3 to form a sixth suspension. The sixth suspension was filtered through a 200-μm nylon mesh to form a binder material. The components of the copolymer binder of Example 9 and their respective ratios are illustrated in Table 1 below.

[0297] Preparation of the polymer binder of Example 10

[0298] 9.07 g of sodium hydroxide (NaOH) was added to a round-bottom flask containing 380 g of distilled water. The mixture was stirred at 80 rpm for 30 minutes to obtain a first suspension.

[0299] 19.68 g of acrylic acid was added to the first suspension. The mixture was further stirred at 80 rpm for 30 minutes to obtain a second suspension.

[0300] 12.94 g of acrylamide was dissolved in 10 g of deionized water to form an acrylamide solution. Thereafter, 22.94 g of the acrylamide solution was added to the second suspension. The mixture was further heated to 55 °C and stirred at 80 rpm for 45 minutes to obtain a third suspension.

[0301] 29.52 g of acrylonitrile was added to the third suspension. The mixture was further stirred at 80 rpm for 10 minutes to obtain a fourth suspension.

[0302] In addition, 0.015 g of a water-soluble free radical initiator (ammonium persulfate, APS; purchased from Aladdin Industrial Corporation, China) was dissolved in 3 g of deionized water, and 0.0075 g of a reducing agent (sodium bisulfite; purchased from Tianjin Damao Chemical Reagent Factory, China) was dissolved in 1.5 g of deionized water. 3.015 g of the APS solution and 1.5075 g of the sodium bisulfite solution were added to the fourth suspension. The mixture was stirred at 55 °C at 200 rpm for 24 hours to obtain a fifth suspension.

[0303] After complete reaction, the temperature of the fifth suspension was lowered to 25 °C. 3.72 g of NaOH was dissolved in 400 g of deionized water. Thereafter, 403.72 g of the sodium hydroxide solution was added dropwise to the fifth suspension to adjust the pH to 7.3 to form a sixth suspension. The sixth suspension was filtered through a 200-μm nylon mesh to form a binder material. The components of the copolymer binder of Example 10 and their respective ratios are illustrated in Table 1 below.

[0304] Preparation of the polymer binder of Example 11

[0305] 6.23 g of sodium hydroxide (NaOH) was added to a round-bottom flask containing 380 g of distilled water. The mixture was stirred at 80 rpm for 30 minutes to obtain a first suspension.

[0306] 14.58 g of acrylic acid was added to the first suspension. The mixture was further stirred at 80 rpm for 30 minutes to obtain a second suspension.

[0307] 5.75 g of acrylamide was dissolved in 10 g of deionized water to form an acrylamide solution. Thereafter, 15.75 g of the acrylamide solution was added to the second suspension. The mixture was further heated to 55 °C and stirred at 80 rpm for 45 minutes to obtain a third suspension.

[0308] 38.64 g of acrylonitrile was added to the third suspension. The mixture was further stirred at 80 rpm for 10 minutes to obtain a fourth suspension.

[0309] In addition, 0.015 g of a water-soluble free radical initiator (ammonium persulfate, APS; purchased from Aladdin Industrial Corporation, China) was dissolved in 3 g of deionized water, and 0.0075 g of a reducing agent (sodium bisulfite; purchased from Tianjin Damao Chemical Reagent Factory, China) was dissolved in 1.5 g of deionized water. 3.015 g of the APS solution and 1.5075 g of the sodium bisulfite solution were added to the fourth suspension. The mixture was stirred at 55 °C at 200 rpm for 24 hours to obtain a fifth suspension.

[0310] After the reaction was complete, the temperature of the fifth suspension was lowered to 25 °C. 3.72 g of NaOH was dissolved in 400 g of deionized water. Thereafter, 403.72 g of the sodium hydroxide solution was added dropwise to the fifth suspension to adjust the pH to 7.3 to form a sixth suspension. The sixth suspension was filtered through a 200-μm nylon mesh to form a binder material. The components of the copolymer binder of Example 11 and their respective ratios are shown in Table 1 below.

[0311] Assembly of the pouch-type lithium-ion full cells of Examples 8-11

[0312] A) Preparation of a positive electrode

[0313] The positive electrode was prepared by the method described in Example 4, except that the binder materials prepared in Examples 8-11 were used respectively to prepare the cathodes of Examples 8-11.

[0314] B) Preparation of a negative electrode

[0315] The negative electrode was prepared by the method described in Example 4.

[0316] C) Assembly of a pouch-type cell

[0317] Prepare a pouch-type lithium-ion battery by the method described in Example 4. Then, subject the assembled pouch-type battery to repeated cycling in the same manner as in Example 4.

[0318] Recovery of the batteries of Examples 8-11

[0319] Recycle the battery in the same manner as in Example 4. Measure the stripping success rate and recovery rate of the cathode material after stripping and present them in Table 1 below.

[0320] Assembly of the pouch-type lithium-ion full cell of Example 12

[0321] Prepare a pouch-type lithium-ion battery by the method described in Example 4. Then, subject the assembled pouch-type battery to repeated cycling in the same manner as in Example 4.

[0322] Recovery of the battery of Example 12

[0323] A) Discharge and disassembly of a pouch-type cell

[0324] Discharge and disassemble the used lithium-ion battery by the same method described in Example 4.

[0325] B) Preparation of a stripping solution

[0326] Add 56.1 g of anhydrous potassium hydroxide (Sigma-Aldrich, USA) to 1000 g of deionized water to form a stripping solution with a concentration of 1.0 M.

[0327] C) Immersion of the cathode in the stripping solution

[0328] Immerse and strip the cathode by the method described in Example 4, except that the above-mentioned stripping solution is used. Measure the stripping success rate and recovery rate of the cathode material after stripping and present them in Table 1 below.

[0329] Assembly of the pouch-type lithium-ion full cell of Example 13

[0330] Prepare a pouch-type lithium-ion battery by the method described in Example 4, except that 276 g of NMC532 is replaced with the same weight of LCO. Then, subject the assembled pouch-type battery to repeated cycling in the same manner as in Example 4.

[0331] Assembly of the pouch-type lithium-ion full cell of Example 14

[0332] A pouch-type lithium-ion battery was prepared by the method described in Example 4, except that 276 g of NMC532 was replaced with the same weight of LFP (Tianjin Sitelan Energy Technology Co., Ltd., China). Then the assembled pouch-type battery was cycled repeatedly in the same manner as in Example 4.

[0333] Assembly of the pouch-type lithium-ion full cell of Example 15

[0334] A pouch-type lithium-ion battery was prepared by the method described in Example 4, except that when preparing the polymer binder, 23.30 g of 2-ethylacrylic acid was used to replace 16.77 g of acrylic acid when preparing the second suspension. Then the assembled pouch-type battery was cycled repeatedly in the same manner as in Example 4.

[0335] Assembly of the pouch-type lithium-ion full cell of Example 16

[0336] A pouch-type lithium-ion battery was prepared by the method described in Example 4, except that when preparing the polymer binder, 25.16 g of vinylsulfonic acid was used to replace 16.77 g of acrylic acid when preparing the second suspension. Then the assembled pouch-type battery was cycled repeatedly in the same manner as in Example 4.

[0337] Recovery of the batteries of Examples 13-16

[0338] The battery was recycled in the same manner as in Example 4. The stripping success rate and recovery rate of the cathode material after stripping were measured and are shown in Table 1 below.

[0339] Assembly of the pouch-type lithium-ion full cell of Comparative Example 1

[0340] A) Preparation of a positive electrode

[0341] In a 500 mL round-bottom flask, 10 g of polyvinylidene fluoride PVDF ( 5130, purchased from Solvay, Belgium) as the polymer binder was dispersed in 250 g of NMP (≥99%, Sigma-Aldrich, USA), and at the same time, it was stirred with an overhead stirrer at 500 rpm for about 3 hours to prepare the first suspension.

[0342] Thereafter, 15 g of SuperP was added to the first suspension and stirred at 1200 rpm for 30 minutes to obtain the second suspension.

[0343] At 25 °C, 225 g of NMC532 was dispersed into the second suspension while stirring with a overhead stirrer to prepare the third suspension. Then, the third suspension was degassed at a pressure of about 10 kPa for 1 hour. The third suspension was further stirred at a speed of 1200 rpm at 25 °C for about 90 minutes to form a homogenized cathode slurry.

[0344] The homogenized cathode slurry was coated onto both sides of an aluminum foil with a thickness of 16 μm as a current collector using a doctor blade coater with a gap width of 120 μm. The coated slurry on the aluminum foil was dried at 85 °C in an electric heating oven to form a cathode electrode layer. The drying time was about 120 minutes. Then the electrode was pressed to reduce the thickness of the cathode electrode layer to 34 μm.

[0345] B) Preparation of a negative electrode

[0346] The negative electrode was prepared in the same manner as in Example 2.

[0347] C) Assembly of a pouch-type cell

[0348] A pouch-type battery was assembled in the same manner as in Example 2. Then the assembled pouch-type battery was cycled repeatedly in the same manner as in Example 2.

[0349] Recovery of the battery of Comparative Example 1

[0350] The battery was recycled in the same manner as in Example 2, except that if the stripping was incomplete, the reaction was terminated after five minutes. The stripping success rate and recovery rate of the cathode material after stripping were measured and are shown in Table 1 below.

[0351] Assembly of the pouch-type lithium-ion full cell of Comparative Example 2

[0352] A pouch-type lithium-ion battery was prepared by the method described in Example 1. Then the assembled pouch-type battery was cycled repeatedly in the same manner as in Example 1.

[0353] Recovery of the battery of Comparative Example 2

[0354] The battery was recycled in the same manner as in Example 1, except that when preparing the stripping solution, no stripping agent was added and only 1000 g of deionized water was added. If the stripping was incomplete, the reaction was terminated after five minutes. The stripping success rate and recovery rate of the cathode material after stripping were measured and are shown in Table 1 below.

[0355] Assembly of the pouch-type lithium-ion full cell of Comparative Example 3

[0356] A pouch-type lithium-ion battery was prepared by the method described in Example 1. Then, the assembled pouch-type battery was subjected to repeated cycling in the same manner as in Example 1.

[0357] Recovery of the battery of Comparative Example 3

[0358] A) Discharge and disassembly of a pouch-type cell

[0359] The spent lithium-ion battery was discharged and disassembled by the same method as described in Example 1.

[0360] B) Preparation of a stripping solution

[0361] 4.00 g of anhydrous sodium hydroxide (Sigma-Aldrich, USA) was added to 1000 g of deionized water to form a stripping solution with a concentration of 0.10 M.

[0362] C) Immersion of the cathode in the stripping solution

[0363] The cathode was immersed and stripped by the method described in Example 1, except that the above-mentioned stripping solution was used. If the stripping was incomplete, the reaction was terminated after five minutes. The stripping success rate and recovery rate of the stripped cathode material were measured and are shown in Table 1 below.

[0364] Assembly of the pouch-type lithium-ion full cell of Comparative Example 4

[0365] A pouch-type lithium-ion battery was prepared by the method described in Example 2, except that when preparing the polymer binder, 9.47 g of sodium hydroxide was added when preparing the first suspension, 20.41 g of acrylic acid was added when preparing the second suspension, acrylamide was not added when preparing the third suspension, and 38.64 g of acrylonitrile was added when preparing the fourth suspension. Then, the assembled pouch-type battery was subjected to repeated cycling in the same manner as in Example 2.

[0366] Assembly of the pouch-type lithium-ion full cell of Comparative Example 5

[0367] A pouch-type lithium-ion battery was prepared by the method described in Example 2, except that when preparing the polymer binder, 2.19 g of sodium hydroxide was added when preparing the first suspension, 7.29 g of acrylic acid was added when preparing the second suspension, 12.94 g of acrylamide was added when preparing the third suspension, and 38.64 g of acrylonitrile was added when preparing the fourth suspension. Then, the assembled pouch-type battery was subjected to repeated cycling in the same manner as in Example 2.

[0368] Assembly of the pouch-type lithium-ion full cell of Comparative Example 6

[0369] A pouch-type lithium-ion battery was prepared by the method described in Example 2, except that when preparing the polymer binder, 4.21 g of sodium hydroxide was added when preparing the first suspension, 10.93 g of acrylic acid was added when preparing the second suspension, 25.16 g of acrylamide was added when preparing the third suspension, and 26.84 g of acrylonitrile was added when preparing the fourth suspension. Then the assembled pouch-type battery was cycled repeatedly in the same manner as in Example 2.

[0370] Recovery of the batteries of Comparative Examples 4-6

[0371] The battery was recycled in the same manner as in Example 2, except that if the stripping was incomplete, the reaction was terminated after five minutes. The stripping success rate and recovery rate of the cathode material after stripping were measured and are shown in Table 1 below.

[0372]

[0373] Although the present invention has been described in connection with a limited number of embodiments, the specific features of one embodiment should not limit the other embodiments of the present invention. In some embodiments, the method may include a plurality of steps not mentioned herein. In other embodiments, the method does not include or substantially does not contain any steps not enumerated herein. There are variations and changes based on the described embodiments. The appended claims are intended to cover all such variations and changes that fall within the scope of the present invention.

Claims

1. A method for stripping a composite by immersing the composite in a stripping solution, wherein the composite comprises a metal substrate and a coating applied on one or both sides of the metal substrate, wherein the stripping solution comprises a stripping agent and an aqueous solvent, the stripping agent is a water-soluble strong base, wherein the coating comprises a copolymer binder, and wherein the copolymer binder comprises a structural unit (a) derived from a monomer selected from the group consisting of monomers containing a carboxylic acid group, monomers containing a sulfonic acid group, monomers containing a phosphonic acid group, monomers containing a carboxylate group, monomers containing a sulfonate group, monomers containing a phosphonate group, and combinations thereof, wherein based on the total molar number of monomer units in the copolymer binder, the proportion of the structural unit (a) in the copolymer is 15% to 30% by mole; wherein the copolymer further comprises a structural unit (b), wherein the structural unit (b) is derived from a monomer selected from the group consisting of monomers containing an amide group, monomers containing a hydroxyl group, and combinations thereof, wherein based on the total molar number of monomer units in the copolymer binder, the proportion of the structural unit (b) in the copolymer is 5% to 20% by mole; and wherein the copolymer further comprises a structural unit (c), wherein the structural unit (c) is derived from a monomer selected from the group consisting of monomers containing a nitrile group, monomers containing an ester group, monomers containing an epoxy group, fluorine-containing monomers, and combinations thereof.

2. The method according to claim 1, wherein the concentration of the stripping agent in the stripping solution is 0.3 to 3 M.

3. The method according to claim 2, wherein the stripping agent is selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, calcium oxide, strontium oxide, barium oxide, and combinations thereof.

4. The method according to claim 2, wherein the aqueous solvent is water.

5. The method according to claim 2, wherein the aqueous solvent comprises water as a main component and a minor component, wherein the proportion of water in the aqueous solvent is greater than 51% and less than 100% by weight, and wherein the minor component is selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, tert-butanol, n-butanol, acetone, dimethyl ketone, methyl ethyl ketone, ethyl acetate, isopropyl acetate, propyl acetate, butyl acetate, and combinations thereof.

6. The method according to claim 1, wherein the monomer containing a carboxylic acid group is selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, 2-butylcrotonic acid, cinnamic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, 4,4-dimethylitaconic acid, 2-ethylacrylic acid, isocrotonic acid, cis-2-pentenoic acid, trans-2-pentenoic acid, angelic acid, tiglic acid, 3,3-dimethylacrylic acid, 3-propylacrylic acid, trans-2-methyl-3-ethylacrylic acid, cis-2-methyl-3-ethylacrylic acid, 3-isopropylacrylic acid, trans-3-methyl-3-ethylacrylic acid, cis-3-methyl-3-ethylacrylic acid, 2-isopropylacrylic acid, trimethylacrylic acid, 2-methyl-3,3-diethylacrylic acid, 3-butylacrylic acid, 2-butylacrylic acid, 2-pentylacrylic acid, 2-methyl-2-hexenoic acid, trans-3-methyl-2-hexenoic acid, 3-methyl-3-propylacrylic acid, 2-ethyl-3-propylacrylic acid, 2,3-diethylacrylic acid, 3,3-diethylacrylic acid, 3-methyl-3-hexylacrylic acid, 3-methyl-3-tert-butylacrylic acid, 2-methyl-3-pentylacrylic acid, 3-methyl-3-pentylacrylic acid, 4-methyl-2-hexenoic acid, 4-ethyl-2-hexenoic acid, 3-methyl-2-ethyl-2-hexenoic acid, 3-tert-butylacrylic acid, 2,3-dimethyl-3-ethylacrylic acid, 3,3-dimethyl-2-ethylacrylic acid, 3-methyl-3-isopropylacrylic acid, 2-methyl-3-isopropylacrylic acid, trans-2-octenoic acid, cis-2-octenoic acid, trans-2-decenoic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, bromomaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, difluoromaleic acid, nonyl hydrogen maleate, decyl hydrogen maleate, dodecyl hydrogen maleate, octadecyl hydrogen maleate, fluoroalkyl hydrogen maleate, maleic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, acrylic anhydride, methacrylic anhydride, methacrolein, methacryloyl chloride, methacryloyl fluoride, methacryloyl bromide, and combinations thereof.

7. The method according to claim 1, wherein the carboxylate group-containing monomer is selected from the group consisting of acrylate, methacrylate, crotonate, 2-butylcrotonate, cinnamate, maleate, maleic anhydride salt, fumarate, itaconate, itaconic anhydride salt, 4,4-dimethylitaconate, 2-ethylacrylate, isocrotonate, cis-2-pentenoate, trans-2-pentenoate, angelate, tiglate, 3,3-dimethylacrylate, 3-propylacrylate, trans-2-methyl-3-ethylacrylate, cis-2-methyl-3-ethylacrylate, 3-isopropylacrylate, trans-3-methyl-3-ethylacrylate, cis-3-methyl-3-ethylacrylate, 2-isopropylacrylate, trimethylacrylate, 2-methyl-3,3-diethylacrylate, 3-butylacrylate, 2-butylacrylate, 2-pentylacrylate, 2-methyl-2-hexenoate, trans-3-methyl-2-hexenoate, 3-methyl-3-propylacrylate, 2-ethyl-3-propylacrylate, 2,3-diethylacrylate, 3,3-diethylacrylate, 3-methyl-3-hexylacrylate, 3-methyl-3-tert-butylacrylate, 2-methyl-3-pentylacrylate, 3-methyl-3-pentylacrylate, 4-methyl-2-hexenoate, 4-ethyl-2-hexenoate, 3-methyl-2-ethyl-2-hexenoate, 3-tert-butylacrylate, 2,3-dimethyl-3-ethylacrylate, 3,3-dimethyl-2-ethylacrylate, 3-methyl-3-isopropylacrylate, 2-methyl-3-isopropylacrylate, trans-2-octenoate, cis-2-octenoate, trans-2-decenoate, α-acetoxyacrylate, β-trans-aryloxyacrylate, α-chloro-β-E-methoxyacrylate, methylmaleate, dimethylmaleate, phenylmaleate, bromomaleate, chloromaleate, dichloromaleate, fluoromaleate, difluoromaleate, and combinations thereof.

8. The method according to claim 1, wherein the sulfonic acid group-containing monomer is selected from the group consisting of vinylsulfonic acid, methylvinylsulfonic acid, allylvinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-sulfoethyl methacrylate, 2-methyl-2-propene-1-sulfonic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid, 3-allyloxy-2-hydroxy-1-propanesulfonic acid, allyl hydrogen sulfate, vinyl hydrogen sulfate, and combinations thereof.

9. The method according to claim 1, wherein the monomer containing a sulfonate group is selected from the group consisting of vinyl sulfonate, methyl vinyl sulfonate, allyl vinyl sulfonate, allyl sulfonate, methallyl sulfonate, styrene sulfonate, 2-sulfoethyl methacrylate, 2-methyl-2-propene-1-sulfonate, 2-acrylamido-2-methyl-1-propane sulfonate, 3-allyloxy-2-hydroxy-1-propane sulfonate, allyl sulfate, vinyl sulfate, and combinations thereof.

10. The method according to claim 1, wherein the monomer containing a phosphonic acid group is selected from the group consisting of vinyl phosphonic acid, allyl phosphonic acid, vinylbenzyl phosphonic acid, acrylamide alkyl phosphonic acid, methacrylamide alkyl phosphonic acid, acrylamide alkyl diphosphonic acid, acrylyl phosphonic acid, 2-methacryloyloxyethyl phosphonic acid, bis(2-methacryloyloxyethyl) phosphonic acid, ethylene 2-methacryloyloxyethyl phosphonic acid, ethyl-2-methacryloyloxyethyl phosphonic acid, allyl hydrogen phosphate, vinyl hydrogen phosphate, and combinations thereof.

11. The method according to claim 1, wherein the monomer containing a phosphonate group is selected from the group consisting of vinyl phosphonate, allyl phosphonate, vinylbenzyl phosphonate, acrylamide alkyl phosphonate, methacrylamide alkyl phosphonate, acrylamide alkyl diphosphonate, acrylyl phosphonate, 2-methacryloyloxyethyl phosphonate, bis(2-methacryloyloxyethyl) phosphonate, ethylene 2-methacryloyloxyethyl phosphonate, ethyl-2-methacryloyloxyethyl phosphonate, allyl phosphate, vinyl phosphate, and combinations thereof.

12. The method according to claim 1, wherein the monomer containing an amide group is selected from the group consisting of acrylamide, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-n-propylmethacrylamide, N-isopropylmethacrylamide, isopropylacrylamide, N-n-butylmethacrylamide, N-isobutylmethacrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N-hydroxymethylmethacrylamide, N-(methoxymethyl)methacrylamide, N-(ethoxymethyl)methacrylamide, N-(propoxymethyl)methacrylamide, N-(butoxymethyl)methacrylamide, N,N-dimethylmethacrylamide, N-(3-(dimethylamino)propyl)methacrylamide, N-(2-(dimethylamino)ethyl)methacrylamide, N,N-(dihydroxymethyl)methacrylamide, diacetone methacrylamide, diacetone acrylamide, methacryloylmorpholine, N-hydroxymethacrylamide, N-methoxymethacrylamide, N-methoxymethylmethacrylamide, N,N'-methylenebisacrylamide (MBA), N-hydroxymethylacrylamide, and combinations thereof.

13. The method according to claim 1, wherein, based on the total molar number of monomer units in the copolymer binder, the proportion of the structural unit (c) in the copolymer is 50% to 75% by mole.

14. The method according to claim 1, wherein the nitrile group-containing monomer is selected from the group consisting of acrylonitrile, α-halopropionitrile, α-alkylacrylonitrile, α-chloropropionitrile, α-bromopropionitrile, α-fluoropropionitrile, methacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-n-hexylacrylonitrile, α-methoxyacrylonitrile, 3-methoxyacrylonitrile, 3-ethoxyacrylonitrile, α-acetoxyacrylonitrile, α-phenylacrylonitrile, α-tolylacrylonitrile, α-(methoxyphenyl)acrylonitrile, α-(chlorophenyl)acrylonitrile, α-(cyanophenyl)acrylonitrile, vinylidene cyanide, and combinations thereof.

15. The method according to claim 1, wherein the metal substrate is in the form of a foil, sheet, film, or a combination thereof, and wherein the metal substrate is selected from the group consisting of titanium, nickel, aluminum, copper, platinum, gold, silver, chromium, zirconium, tungsten, molybdenum, tin, vanadium, zinc, cadmium, iron, cobalt, lead, and alloys thereof.

16. The method according to claim 1, wherein, The metal substrate is in the form of a porous body having a three-dimensional network structure, and wherein the metal substrate is selected from the group consisting of titanium, nickel, aluminum, copper, platinum, gold, silver, chromium, zirconium, tungsten, molybdenum, tin, vanadium, zinc, cadmium, iron, cobalt, lead, and alloys thereof.

17. The method according to claim 1, wherein the weight ratio of the composite to the stripping solution is 0.01% to 50%, and wherein the temperature at which the composite is immersed in the stripping solution is 10°C to 90°C.

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