Battery cell, battery device, and electric device

Abstract

The present application relates to a battery cell, a battery device, and an electric device. A negative electrode material layer in the battery cell comprises a negative electrode active material and a conductive binder. The negative electrode active material comprises a silicon-based material. The conductive binder comprises a binder and a conductive agent. The conductive agent comprises carbon nanotubes. The binder comprises a structural unit (a) and a structural unit (b). The structural unit (a) is derived from any one or a combination of two of a monomer containing a carboxylic acid group and a monomer containing a carboxylate group. The structural unit (b) is derived from any one or a combination of two or more of a monomer containing a sulfonic acid group, a monomer containing a phosphoric acid group, a monomer containing a sulfonate group, and a monomer containing a phosphate group. The battery cell has good fast charging performance.

Description

A battery cell, a battery device, and an electrical device.

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application 202510111710.X, filed on January 23, 2025, entitled “A battery cell, a battery device and an electrical device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, specifically to a battery cell, a battery device, and an electrical device. Background Technology

[0004] In recent years, secondary batteries, represented by lithium-ion batteries, have developed rapidly and are widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other fields. Due to the significant development of secondary batteries, higher performance requirements have been placed on them. Silicon-based anode materials are considered to have good application prospects due to their high theoretical specific capacity. However, batteries using silicon-based anode materials still suffer from problems such as poor fast-charging performance. Summary of the Invention

[0005] The purpose of this application is to provide a battery cell, a battery device, and an electrical device, wherein the battery cell has good fast charging performance mainly by improving the negative electrode plate.

[0006] Therefore, the first aspect of this application provides a battery cell, which includes a positive electrode, a separator, and a negative electrode;

[0007] The negative electrode sheet includes a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector; the negative electrode material layer includes a negative electrode active material and a conductive binder;

[0008] The negative electrode active material includes silicon-based materials;

[0009] The conductive binder includes an binder and a conductive agent; the conductive agent includes carbon nanotubes.

[0010] The adhesive comprises structural unit (a) and structural unit (b);

[0011] The structural unit (a) is derived from monomers selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups;

[0012] The structural unit (b) is derived from monomers selected from the group consisting of any one or any combination of two or more monomers containing sulfonic acid groups, phosphate groups, sulfonate groups, or phosphate groups.

[0013] Silicon-based materials are prone to significant volume expansion during lithium intercalation, especially during high-rate charging, which can even cause powder shedding and film detachment from the negative electrode. Furthermore, silicon-based materials have poor conductivity and high polarization, easily resulting in low charge / discharge efficiency of the negative electrode. These factors make silicon-based negative electrode materials unsuitable for fast charging requirements.

[0014] Carbon nanotubes, with their linear structure and certain mechanical strength, form a three-dimensional conductive network around silicon-based materials under the action of a binder, thus restraining the expansion of the silicon-based materials. This increases the stability of silicon-based materials during fast charging.

[0015] Furthermore, the electronic conductivity, ion transport kinetics, and transport rate of the negative electrode are improved through the following aspects, thereby enhancing fast-charging performance. Firstly, carbon nanotubes are used, which possess long-range ion-conducting and electrical conductivity properties. Secondly, structural unit (a) is employed in the binder; the carboxyl groups can combine with lithium ions to form lithium-ion transport channels, increasing the lithium-ion transport path. Thirdly, structural unit (b) contains sulfonate and phosphate groups. These two groups have significant electronegativity differences with sulfur and oxygen atoms, and with phosphorus and oxygen atoms, respectively. Compared to carboxylate groups, they are more polar, and their lone pairs of electrons can interact with lithium ions in the electrolyte to form coordinate bonds, thus promoting the desolvation of lithium ions and significantly improving the kinetic behavior of lithium ions at the electrode / electrolyte interface, making it easier for lithium ions to diffuse into the negative electrode material layer. In addition, sulfonate and phosphate groups can also form lithium-ion transport channels, increasing the ion transport rate.

[0016] In some embodiments, the conductive agent has polymer grafting, the polymer comprising a structural unit (a') derived from a monomer selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups.

[0017] When a conductive agent is grafted onto a polymer containing a structural unit (a'), the carboxyl group can form a strong hydrogen bond with functional groups such as hydroxyl groups on the surface of silicon-based materials. This helps to improve the interaction between the binder and the conductive agent and the silicon-based material, and better play the role of suppressing expansion. This is not only beneficial to improving the stability of the battery during fast charging, but also beneficial to improving the cycle performance of the battery.

[0018] In some embodiments, the adhesive further includes structural unit (c); and / or, the polymer further includes structural unit (c');

[0019] The structural unit (c) and structural unit (c') are each independently derived from any one or any combination of two or more monomers selected from the group consisting of monomers containing amide groups, monomers containing nitrile groups, monomers containing hydroxyl groups, monomers containing ester groups, and fluorine-containing monomers.

[0020] By applying the above-mentioned structural units in binders and / or polymers, battery performance can be further improved. For example, nitrile groups have strong polarity, which can improve adhesion and improve the stability of the negative electrode material layer; amide groups can play a good role in suspending and dispersing particles such as negative electrode active materials and conductive agents, improving the dispersion of these materials in the negative electrode material layer; ester groups have a certain degree of hydrophobicity, which can form good affinity with negative electrode active materials (such as graphite particles) and have an encapsulation effect; hydroxyl groups have hydrophilicity and reactivity, which can form hydrogen bonds or ionic bonds with functional groups on the surface of silicon-based materials, especially silanol groups. This interaction can significantly improve adhesion, making the electrode material stable and less prone to detachment during charging and discharging; fluorine can optimize the interface structure between the binder and the negative electrode active material, improve the electron and ion transport efficiency, which helps to improve the charge and discharge rate and energy density of the battery.

[0021] In some embodiments, the structural unit (c) is derived from a combination of monomers including the following group: monomers containing amide groups, monomers containing nitrile groups, monomers containing hydroxyl groups, and monomers containing ester groups.

[0022] When the structural unit (c) contains the above-mentioned groups, it can play the role of multiple groups at the same time, which is beneficial to improving the battery performance.

[0023] In some embodiments, the adhesive contains structural unit (a) at a mass fraction of 20% to 70%, and structural unit (b) at a mass fraction of 5% to 50%; and / or,

[0024] In the polymer-grafted conductive agent, the mass fraction of the structural unit (a') is 20% to 80%.

[0025] In the binder, controlling the mass fraction of each structural unit within the aforementioned range is beneficial for balancing the binder's electrical conductivity and ion conductivity. This enhances the bonding performance of the conductive binder while significantly improving the ion conductivity of the negative electrode sheet.

[0026] In polymer-grafted conductive agents, a mass fraction of structural unit (a') within the above-mentioned range is beneficial to enhancing the bonding performance of the conductive agent.

[0027] In some embodiments, the structural unit (c) in the adhesive has a mass fraction of 0.1% to 70%; and / or,

[0028] In the polymer-grafted conductive agent, the mass fraction of the structural unit (c') is 5% to 40%.

[0029] In the binder, the mass fraction of structural unit (c) within the above range is beneficial to maintaining good adhesion while further reducing the brittleness of the negative electrode sheet and increasing the toughness of the electrode sheet.

[0030] In polymer-grafted conductive agents, a mass fraction of structural unit (c') within the above-mentioned range is beneficial for improving the stability of the conductive binder.

[0031] In some embodiments, the mass ratio of the adhesive to the conductive agent is 2 to 100.

[0032] Controlling the weight ratio of binder and carbon nanotubes within the above range can effectively improve electrode flexibility, reduce negative electrode material demolding, and improve the anti-settling properties of conductive binder.

[0033] In some embodiments, the adhesive has a weight-average molecular weight of 500,000 to 2,500,000; and / or,

[0034] The polymer grafted with the conductive agent has a weight-average molecular weight of 2,000 to 30,000.

[0035] Controlling the weight-average molecular weight of the binder within the above range is beneficial for adjusting the viscosity of the conductive binder and enhancing its bonding performance, while also helping to reduce electrode brittleness and increase electrode toughness.

[0036] By controlling the weight-average molecular weight of the polymer grafted with carbon nanotubes within the above-mentioned range, the conductive binder can achieve high stability while also enabling the negative electrode slurry to have good anti-gelling properties, and at the same time, it is beneficial to adjust the viscosity of the conductive binder.

[0037] In some embodiments, the carbon nanotubes include at least one of single-walled carbon nanotubes, oligowalled carbon nanotubes, or multi-walled carbon nanotubes; and / or,

[0038] The length of the carbon nanotubes is 0.5–30 μm.

[0039] Controlling the length of carbon nanotubes within the above-mentioned range is beneficial for the suspension of carbon nanotubes in conductive binders and negative electrode slurries.

[0040] In some embodiments, the silicon-based material includes at least one of silicon-carbon materials, silicon-oxygen materials, elemental silicon, and silicon alloys.

[0041] In the embodiments of this application, when the above-mentioned silicon-based materials are used, they can significantly improve the rate performance of the battery. Furthermore, using the above-mentioned materials as negative electrode active materials is beneficial to improving the energy density of lithium-ion batteries.

[0042] In some embodiments, the silicon-based material accounts for 5% to 15% of the mass of the negative electrode material layer; and / or,

[0043] The conductive adhesive accounts for 0.5% to 2% of the total mass.

[0044] When the mass percentage of silicon-based material is within the above range, good energy density and rate performance can be achieved. When the mass percentage of the conductive binder is greater than or equal to 0.5%, it can effectively improve the expansion of silicon-based material and enhance ion conduction capability. Furthermore, when its mass percentage does not exceed 2%, the negative electrode active material can have a correspondingly higher mass percentage, which is beneficial for maintaining good energy density.

[0045] A second aspect of this application provides a conductive adhesive comprising an adhesive and a conductive agent; the conductive agent comprising carbon nanotubes.

[0046] The adhesive comprises structural unit (a) and structural unit (b);

[0047] The structural unit (a) is derived from monomers selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups;

[0048] The structural unit (b) is derived from monomers selected from the group consisting of any one or any combination of two or more monomers containing sulfonic acid groups, phosphate groups, sulfonate groups, or phosphate groups.

[0049] In some embodiments, the conductive agent has polymer grafting, the polymer comprising a structural unit (a') derived from a monomer selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups.

[0050] In some embodiments, the adhesive further includes structural unit (c); and / or, the polymer further includes structural unit (c');

[0051] The structural unit (c) and structural unit (c') are each independently derived from any one or any combination of two or more monomers selected from the group consisting of monomers containing amide groups, monomers containing nitrile groups, monomers containing hydroxyl groups, monomers containing ester groups, and fluorine-containing monomers.

[0052] In some embodiments, the structural unit (c) is derived from a combination of monomers including the following group: monomers containing amide groups, monomers containing nitrile groups, monomers containing hydroxyl groups, and monomers containing ester groups.

[0053] In some embodiments, the adhesive contains structural unit (a) at a mass fraction of 20% to 70%, and structural unit (b) at a mass fraction of 5% to 50%; and / or,

[0054] In the polymer-grafted conductive agent, the mass fraction of the structural unit (a') is 20% to 80%.

[0055] In some embodiments, the structural unit (c) in the adhesive has a mass fraction of 0.1% to 70%; and / or,

[0056] In the polymer-grafted conductive agent, the mass fraction of the structural unit (c') is 5% to 40%.

[0057] In some embodiments, the mass ratio of the adhesive to the conductive agent is 2 to 100.

[0058] In some embodiments, the adhesive has a weight-average molecular weight of 500,000 to 2,500,000; and / or,

[0059] The polymer grafted with the conductive agent has a weight-average molecular weight of 2,000 to 30,000.

[0060] In some embodiments, the carbon nanotubes include at least one of single-walled carbon nanotubes, oligowalled carbon nanotubes, or multi-walled carbon nanotubes; and / or,

[0061] The length of the carbon nanotubes is 0.5–30 μm.

[0062] In some embodiments, at 25°C, the viscosity of an aqueous solution of a binder with a solid content of 15% to 25% is 15000 to 31000 mPa·s; and / or,

[0063] At 25°C, the viscosity of an aqueous solution of a conductive agent with a solid content of 0.7%–1.5% is 8000–35000 mPa·s; and / or,

[0064] At 25°C, the viscosity of an aqueous solution of a conductive adhesive with a solid content of 1.5% to 10% is 8000 to 35000 mPa·s.

[0065] When high-viscosity conductive binders are used in silicon-based anodes, they can provide good suspension for the anode active materials. During the preparation of the anode slurry, only a small amount of dispersant, such as sodium carboxymethyl cellulose, is needed to disperse the anode active materials, without the need for a large amount of dispersant, such as sodium carboxymethyl cellulose, to maintain the suspension of the anode slurry. This can further increase the content of the anode active materials in the anode slurry, and at the same time improve the viscosity stability of the anode slurry.

[0066] A third aspect of this application provides a battery device comprising the battery cell described in the first aspect of this application.

[0067] A fourth aspect of this application provides an electrical device comprising a single battery cell as described in the first aspect of this application, or a battery device as described in the third aspect of this application.

[0068] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of this application more obvious and understandable, the specific implementation methods of this application are listed below. Attached Figure Description

[0069] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. In the drawings:

[0070] Figure 1 is a schematic diagram of a battery cell according to an embodiment of this application;

[0071] Figure 2 is an exploded view of a battery cell according to an embodiment of this application shown in Figure 1;

[0072] Figure 3 is a schematic diagram of a battery module according to an embodiment of this application;

[0073] Figure 4 is a schematic diagram of a battery pack according to an embodiment of this application;

[0074] Figure 5 is an exploded view of the battery pack of one embodiment of this application shown in Figure 4;

[0075] Figure 6 is a schematic diagram of an electrical device in which a single battery cell is used as a power source according to an embodiment of this application.

[0076] Explanation of reference numerals in the attached diagram: 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 End cap. Detailed Implementation

[0077] Exemplary embodiments of this disclosure will now be described in more detail. It should be understood that this disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0078] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is expected that ranges of 60–110 and 80–120 are also included. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0079] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0080] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0081] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0082] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0083] In recent years, rechargeable batteries have made significant progress, leading to higher performance requirements. Silicon-based anode materials are considered promising due to their high theoretical specific capacity. However, silicon-based materials undergo significant volume changes during lithium insertion / extraction, which can easily cause electrode powder shedding and cracking, resulting in insufficient stability of the anode material and thus degrading battery performance.

[0084] In existing technologies, some reports have described methods such as coating to reduce the expansion of silicon-based materials, aiming to mitigate the negative impacts of expansion, such as electrode powder shedding and cracking. However, these methods have very limited effect on improving battery fast-charging performance. This is mainly because these methods primarily improve the stability of the negative electrode material, while important factors affecting battery fast-charging performance also include the ion transport rate of the negative electrode material.

[0085] This application mainly improves the fast-charging performance of the battery by applying a conductive binder to the negative electrode sheet, which simultaneously reduces the expansion of silicon-based materials and improves the electronic conductivity, ionic conductivity and kinetic performance of the negative electrode sheet.

[0086] The solutions described in the embodiments of this application are applicable to battery cells, battery devices using the battery cells, and electrical devices using the battery cells or battery devices.

[0087] battery cell

[0088] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0089] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc. In some embodiments, the battery cell is a lithium-ion battery.

[0090] [Electrode Assembly]

[0091] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator positioned between the positive and negative electrodes. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0092] [Negative electrode plate]

[0093] In some embodiments, a battery cell is provided, which includes a positive electrode, a separator, and a negative electrode.

[0094] The negative electrode sheet includes a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector; the negative electrode material layer includes a negative electrode active material and a conductive binder;

[0095] The negative electrode active material includes silicon-based materials;

[0096] The conductive binder includes an binder and a conductive agent; the conductive agent includes carbon nanotubes.

[0097] The adhesive comprises structural unit (a) and structural unit (b);

[0098] The structural unit (a) is derived from monomers selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups;

[0099] The structural unit (b) is derived from monomers selected from the group consisting of any one or any combination of two or more monomers containing sulfonic acid groups, phosphate groups, sulfonate groups, or phosphate groups.

[0100] Silicon-based materials are prone to significant volume expansion during lithium intercalation, especially during high-rate charging, which can even cause powder shedding and film detachment from the negative electrode. Furthermore, silicon-based materials have poor conductivity and high polarization, easily resulting in low charge / discharge efficiency of the negative electrode. These factors make silicon-based negative electrode materials unsuitable for fast charging requirements.

[0101] Carbon nanotubes, with their linear structure and certain mechanical strength, form a three-dimensional conductive network around silicon-based materials under the action of a binder, thus restraining the expansion of the silicon-based materials. This increases the stability of silicon-based materials during fast charging.

[0102] Furthermore, the electronic conductivity, ion transport kinetics, and transport rate of the negative electrode are improved through the following aspects, thereby enhancing fast-charging performance. Firstly, carbon nanotubes are used, which possess long-range ion-conducting and electrical conductivity properties. Secondly, structural unit (a) is employed in the binder; the carboxyl groups can combine with lithium ions to form lithium-ion transport channels, increasing the lithium-ion transport path. Thirdly, structural unit (b) contains sulfonate and phosphate groups. These two groups have significant electronegativity differences with sulfur and oxygen atoms, and with phosphorus and oxygen atoms, respectively. Compared to carboxylate groups, they are more polar, and their lone pairs of electrons can interact with lithium ions in the electrolyte to form coordinate bonds, thus promoting the desolvation of lithium ions and significantly improving the kinetic behavior of lithium ions at the electrode / electrolyte interface, making it easier for lithium ions to diffuse into the negative electrode material layer. In addition, sulfonate and phosphate groups can also form lithium-ion transport channels, increasing the ion transport rate.

[0103] In some embodiments, the conductive agent has polymer grafting, the polymer comprising a structural unit (a') derived from a monomer selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups.

[0104] When a conductive agent is grafted onto a polymer containing a structural unit (a'), the carboxyl group can form a strong hydrogen bond with functional groups such as hydroxyl groups on the surface of silicon-based materials. This helps to improve the interaction between the binder and the conductive agent and the silicon-based material, and better play the role of suppressing expansion. This is not only beneficial to improving the stability of the battery during fast charging, but also beneficial to improving the cycle performance of the battery.

[0105] In some embodiments, the structural unit (a) and the structural unit (a') are each independently derived from a monomer selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups.

[0106] In some embodiments, the monomer containing a carboxyl group may be a corresponding salt of the monomer containing the carboxyl group; for example, a potassium salt, sodium salt, lithium salt, ammonium salt, etc.

[0107] In some embodiments, the monomer containing a carboxylic acid group has the structural formula shown in formula (I), and / or the monomer containing a carboxylate group has the structural formula shown in formula (I').

[0108] Among them, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C. 1-6 Alkyl, substituted C 1-6 The substituents of the alkyl group are selected from at least one of amino, hydroxyl, and halogen groups;

[0109] R4 is a direct bond, or a substituted or unsubstituted C. 1-6 Alkylene, C 1-6 alkylene amide group, C 1-6 alkeneoxy or C 1-6 The substituted group is selected from at least one of amino, hydroxyl, and halogen groups;

[0110] M is selected from ammonium ions or metal ions (such as potassium ions, sodium ions, lithium ions, etc.).

[0111] In some embodiments, the monomer containing a carboxylic acid group may be selected from the group consisting of: acrylic acid, methacrylic acid, butenoic acid, 3,3-dimethacrylic acid, 2-ethylacrylic acid, 3-propylacrylic acid, trimethacrylic acid, 3-butylacrylic acid, 2-butylacrylic acid, 2-pentylacrylic acid, 2,3-diethylacrylic acid, 3,3-diethylacrylic acid, 2-methyl-3-pentylacrylic acid, 3-methyl-3-pentylacrylic acid, 3-methyl-3-propylacrylic acid, 3-methyl-3-hexylacrylic acid, etc.

[0112] In some embodiments, the monomer containing the carboxyl group may be selected from the group consisting of: acrylates, methacrylates, butenoates, 3,3-dimethylacrylate, 2-ethylacrylate, 3-propylacrylate, trimethylacrylate, 3-butylacrylate, 2-butylacrylate, 2-pentylacrylate, 2,3-diethylacrylate, 3,3-diethylacrylate, 2-methyl-3-pentylacrylate, 3-methyl-3-pentylacrylate, 3-methyl-3-propylacrylate, 3-methyl-3-hexylacrylate, etc.

[0113] In some embodiments, the monomer containing the sulfonate group may be a corresponding salt of the monomer containing the sulfonic acid group; for example, potassium salt, sodium salt, lithium salt, ammonium salt, etc.

[0114] In some embodiments, the monomer containing the sulfonic acid group has the structural formula shown in formula (II), and / or the monomer containing the sulfonate group has the structural formula shown in formula (II').

[0115] Among them, R5, R6, and R7 are each independently selected from H, substituted or unsubstituted C. 1-6 Alkyl, substituted C 1-6 The substituents of the alkyl group are selected from at least one of amino, hydroxyl, and halogen groups;

[0116] R8 is a direct bond, or a substituted or unsubstituted C. 1-6 Alkylene, C 1-6 alkylene amide group, C 1-6 alkeneoxy or C 1-6The substituted group is selected from at least one of amino, hydroxyl, and halogen groups;

[0117] M is selected from ammonium ions or metal ions (such as potassium ions, sodium ions, lithium ions, etc.).

[0118] In some embodiments, the monomer containing the sulfonic acid group may be selected from the group consisting of: vinyl sulfonic acid, allyl sulfonic acid, 2-methylallyl sulfonic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

[0119] In some embodiments, the monomer containing the sulfonate group may be selected from the group consisting of: vinyl sulfonate, allyl sulfonate, and 2-methyl allyl sulfonate.

[0120] In some embodiments, the monomer containing the phosphate group may be a corresponding salt of the monomer containing the phosphate group; for example, potassium salt, sodium salt, lithium salt, ammonium salt, etc.

[0121] In some embodiments, the phosphate-containing monomer has the structural formula shown in formula (III), and / or the phosphate-containing monomer has the structural formula shown in formula (III').

[0122] Among them, R9, R 10 R 11 Each is independently selected from H, substituted or unsubstituted C. 1-6 Alkyl, substituted C 1-6 The substituents of the alkyl group are selected from at least one of amino, hydroxyl, and halogen groups;

[0123] R 12 For direct bonding, or for substituted or unsubstituted C 1-6 Alkylene, C 1-6 alkylene amide group, C 1-6 alkeneoxy or C 1-6 The substituted group is selected from at least one of amino, hydroxyl, and halogen groups;

[0124] M is selected from ammonium ions or metal ions (such as potassium ions, sodium ions, lithium ions, etc.).

[0125] In some embodiments, the phosphate-containing monomer may be selected from the group consisting of: vinylphosphonic acid, 2-methylvinylphosphonic acid, 2-ethylvinylphosphonic acid, allylphosphonic acid, and cis-propenylphosphonic acid.

[0126] In some embodiments, the phosphate-containing monomer may be selected from the group consisting of: vinyl phosphonate, 2-methyl vinyl phosphonate, 2-ethyl vinyl phosphonate, allyl phosphonate, and cis-propenyl phosphate.

[0127] In some embodiments, the adhesive further includes structural unit (c); and / or, the polymer further includes structural unit (c');

[0128] The structural unit (c) and structural unit (c') are each independently derived from any one or any combination of two or more monomers selected from the group consisting of monomers containing amide groups, monomers containing nitrile groups, monomers containing hydroxyl groups, monomers containing ester groups, and fluorine-containing monomers.

[0129] By applying the above-mentioned structural units in binders and / or polymers, battery performance can be further improved. For example, nitrile groups have strong polarity, which can improve adhesion and improve the stability of the negative electrode material layer; amide groups can play a good role in suspending and dispersing particles such as negative electrode active materials and conductive agents, improving the dispersion of these materials in the negative electrode material layer; ester groups have a certain degree of hydrophobicity, which can form good affinity with negative electrode active materials (such as graphite particles) and have an encapsulation effect; hydroxyl groups have hydrophilicity and reactivity, which can form hydrogen bonds or ionic bonds with functional groups on the surface of silicon-based materials, especially silanol groups. This interaction can significantly improve adhesion, making the electrode material stable and less prone to detachment during charging and discharging; fluorine can optimize the interface structure between the binder and the negative electrode active material, improve the electron and ion transport efficiency, which helps to improve the charge and discharge rate and energy density of the battery.

[0130] In some embodiments, the monomer containing the amide group may be selected from the group consisting of: acrylamide, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-n-propylmethacrylamide, N-isopropylmethacrylamide, N-n-butylmethacrylamide, N-isobutylmethacrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N-hydroxymethylmethacrylamide, N,N-dihydroxymethylmethacrylamide, N-hydroxymethylacrylamide, and 2-acrylamido-2-methylpropanesulfonic acid.

[0131] In some embodiments, the monomer containing the nitrile group may be selected from the group consisting of: acrylonitrile, α-chloroacrylonitrile, α-bromoacrylonitrile, α-fluoroacrylonitrile, methacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, and α-hexylacrylonitrile.

[0132] In some embodiments, the monomer containing the hydroxyl group may be selected from the group consisting of: 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, and allyl alcohol.

[0133] In some embodiments, the monomer containing the ester group may be selected from the group consisting of: methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 3,5,5-trimethylhexyl acrylate, and 2-ethylhexyl acrylate.

[0134] In some embodiments, the fluorinated monomer may be selected from the group consisting of C having at least one fluorine substitution. 1-6 Alkyl acrylates, C having at least one fluorine substitution 1-6 Alkyl methacrylates.

[0135] In some embodiments, the structural unit (c) is derived from a combination of monomers including the following group: monomers containing amide groups, monomers containing nitrile groups, monomers containing hydroxyl groups, and monomers containing ester groups.

[0136] When the structural unit (c) contains the above-mentioned groups, it can play the role of multiple groups at the same time, which is beneficial to improving the battery performance.

[0137] In some embodiments, the mass fraction of the structural unit (a) is 20% to 70% based on the mass of the adhesive, for example, it can be about 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, etc.; the mass fraction of the structural unit (b) is 5% to 50%, for example, it can be about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%. In some embodiments, the mass fraction of the structural unit (a') is 20% to 80% based on the mass of the polymer-grafted conductive agent, for example, it can be about 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc.

[0138] In the binder, controlling the mass fraction of each structural unit within the aforementioned range is beneficial for balancing the binder's electrical conductivity and ion conductivity. This enhances the bonding performance of the conductive binder while significantly improving the ion conductivity of the negative electrode sheet.

[0139] In polymer-grafted conductive agents, a mass fraction of structural unit (a') within the above-mentioned range is beneficial to enhancing the bonding performance of the conductive agent.

[0140] In some embodiments, the mass fraction of the structural unit (c) is 0.1% to 70% based on the mass of the adhesive, for example, it can be about 0.1%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%. In some embodiments, the mass fraction of the structural unit (c') is 5% to 40% based on the mass of the polymer-grafted conductive agent, for example, it can be about 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%.

[0141] In the binder, the mass fraction of structural unit (c) within the above range is beneficial to maintaining good adhesion while further reducing the brittleness of the negative electrode sheet and increasing the toughness of the electrode sheet.

[0142] In polymer-grafted conductive agents, a mass fraction of structural unit (c') within the above-mentioned range is beneficial for improving the stability of the conductive binder.

[0143] In some embodiments, the mass ratio of the adhesive to the conductive agent is 2 to 100, for example, it can be about 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, etc.

[0144] Controlling the weight ratio of binder and carbon nanotubes within the above range can effectively improve electrode flexibility, reduce negative electrode material demolding, and improve the anti-settling properties of conductive binder.

[0145] In some embodiments, the weight-average molecular weight of the adhesive is 500,000 to 2,500,000, for example, it can be about 500,000, 550,000, 600,000, 650,000, 700,000, 750,000, 800,000, 850,000, 900,000, 950,000, 1,000,000, 1,300,000, 1,500,000, 2,000,000, 2,500,000, etc. In some embodiments, the weight-average molecular weight of the polymer grafted with the conductive agent is 2,000 to 30,000, for example, it can be about 2,000, 5,000, 10,000, 15,000, 20,000, 25,000, 30,000, etc.

[0146] Controlling the weight-average molecular weight of the binder within the above range is beneficial for adjusting the viscosity of the conductive binder and enhancing its bonding performance, while also helping to reduce electrode brittleness and increase electrode toughness.

[0147] By controlling the weight-average molecular weight of the polymer grafted with carbon nanotubes within the above-mentioned range, the conductive binder can achieve high stability while also enabling the negative electrode slurry to have good anti-gelling properties, and at the same time, it is beneficial to adjust the viscosity of the conductive binder.

[0148] In some embodiments, the carbon nanotubes include at least one of single-walled carbon nanotubes, oligowalled carbon nanotubes, or multiwalled carbon nanotubes. In some embodiments, the length of the carbon nanotubes is 0.5–30 μm, for example, it can be about 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc.

[0149] Conductive binders containing carbon nanotubes are wound around the surface of the negative electrode active material, which can effectively construct a conductive network and inhibit particle expansion of the active material, reducing the rebound of the negative electrode material layer thickness. Controlling the length of the carbon nanotubes within the above-mentioned range is beneficial to the suspension of carbon nanotubes in the conductive binder and negative electrode slurry.

[0150] In some embodiments, the conductive binder in the negative electrode material layer has a mass percentage of 0.5% to 2%, for example, about 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, etc.

[0151] When the mass percentage of the conductive binder is greater than or equal to 0.5%, it can effectively improve the expansion of silicon-based materials and enhance their ion-conducting ability; and when its mass percentage does not exceed 2%, the negative electrode active material can have a correspondingly higher mass percentage, which is beneficial for maintaining good energy density.

[0152] In some embodiments, at 25°C, the viscosity of the aqueous solution of the binder with a solid content of 15% to 25% is 15,000 to 31,000 mPa·s, for example, about 15,000 mPa·s, 16,000 mPa·s, 17,000 mPa·s, 18,000 mPa·s, 19,000 mPa·s, 20,000 mPa·s, 21,000 mPa·s, 23,000 mPa·s, 24,000 mPa·s, 25,000 mPa·s, 26,000 mPa·s, 27,000 mPa·s, 28,000 mPa·s, 29,000 mPa·s, 30,000 mPa·s, and 31,000 mPa·s. In some embodiments, at 25°C, the viscosity of the aqueous solution of the conductive agent with a solid content of 0.7% to 1.5% is 8000 to 35000 mPa·s, for example, it can be about 8000 mPa·s, 10000 mPa·s, 12000 mPa·s, 14000 mPa·s, 16000 mPa·s, 18000 mPa·s, 20000 mPa·s, 22000 mPa·s, 24000 mPa·s, 26000 mPa·s, 28000 mPa·s, 30000 mPa·s, 32000 mPa·s, 34000 mPa·s, or 35000 mPa·s. In some embodiments, at 25°C, the viscosity of the aqueous solution of the conductive binder with a solid content of 1.5% to 10% is 8000 to 35000 mPa·s, for example, it can be about 8000 mPa·s, 10000 mPa·s, 12000 mPa·s, 14000 mPa·s, 16000 mPa·s, 18000 mPa·s, 20000 mPa·s, 22000 mPa·s, 24000 mPa·s, 26000 mPa·s, 28000 mPa·s, 30000 mPa·s, 32000 mPa·s, 34000 mPa·s, 34500 mPa·s, or 35000 mPa·s.

[0153] When high-viscosity conductive binders are used in silicon-based anodes, they can provide good suspension for the anode active materials. During the preparation of the anode slurry, only a small amount of dispersant, such as sodium carboxymethyl cellulose, is needed to disperse the anode active materials, without the need for a large amount of dispersant, such as sodium carboxymethyl cellulose, to maintain the suspension of the anode slurry. This can further increase the content of the anode active materials in the anode slurry, and at the same time improve the viscosity stability of the anode slurry.

[0154] In some embodiments, the method for preparing the conductive adhesive includes:

[0155] A first reaction system comprising monomers for deriving structural unit (a) and monomers for deriving structural unit (b) is provided, and an adhesive is prepared by a first polymerization reaction;

[0156] Provide a conductive agent, the conductive agent comprising carbon nanotubes;

[0157] The conductive agent is mixed with the adhesive to prepare the conductive adhesive;

[0158] in,

[0159] The monomers used to derive structural unit (a) and the monomers used to derive structural unit (a') are each independently selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups and monomers containing carboxylate groups.

[0160] The monomer used to derive structural unit (b) is selected from the group consisting of any one or any combination of two or more monomers containing sulfonic acid groups, phosphate groups, sulfonate groups, and phosphate groups.

[0161] In some embodiments, the conductive agent has polymer grafting, and the method for preparing the conductive agent includes: providing a second reaction system comprising monomers for deriving structural units (a'), mixing the second reaction system with the conductive agent, and preparing the polymer-grafted conductive agent by a second polymerization reaction.

[0162] In some embodiments, the first reaction system further includes a monomer for deriving structural unit (c); and / or, the second reaction system further includes a monomer for deriving structural unit (c');

[0163] The monomers used to derive structural unit (c) and the monomers used to derive structural unit (c') are each independently selected from the group consisting of any one or any combination of two or more monomers containing amide groups, nitrile groups, hydroxyl groups, ester groups, and fluorine groups.

[0164] In some embodiments, the first and second reaction systems further contain initiators, and the polymerization reaction is carried out through the action of the initiators. In some embodiments, the initiators in the first and second reaction systems may be the same or different, and may be independently selected from initiators commonly used in the art. The initiators may include, but are not limited to, persulfates, such as ammonium persulfate, potassium persulfate, and sodium persulfate.

[0165] In some embodiments, the first reaction system and the second reaction system further contain a solvent. In some embodiments, the solvents in the first reaction system and the second reaction system may be the same or different, and the solvents include, but are not limited to, aqueous solvents, such as deionized water.

[0166] In some embodiments, the conductive agent is a dispersion containing carbon nanotubes, and the preparation method can be selected by those skilled in the art according to specific practical needs. For example, a dispersion containing carbon nanotubes can be obtained by ball milling carbon nanotubes to the required length and adding them to a solution containing a dispersant. The dispersant can be a commonly used dispersant in the art, such as sodium carboxymethyl cellulose, polyvinyl alcohol cellulose, etc., but is not limited thereto.

[0167] In some embodiments, the reaction temperature of the first polymerization reaction can be selected according to specific practical needs. For example, the reaction temperature of the first polymerization reaction can be 50℃ to 110℃; for example, it can be 55℃ to 100℃, 60℃ to 90℃, or 70℃ to 80℃, etc. The reaction time of the first polymerization reaction can be selected according to specific practical needs. For example, the reaction time of the first polymerization reaction can be 5h to 20h; for example, it can be 5.5h to 18h, 6h to 16h, 7h to 14h, or 8h to 12h, etc.

[0168] In some embodiments, the reaction temperature of the second polymerization reaction can be selected according to specific practical needs. For example, the reaction temperature of the second polymerization reaction can be 50℃ to 80℃; for example, it can be 55℃ to 75℃, 60℃ to 70℃, or 65℃ to 70℃, etc. The reaction time of the second polymerization reaction can be selected according to specific practical needs. For example, the reaction time of the second polymerization reaction can be 0.5h to 10h; for example, it can be 0.5h to 9h, 0.5h to 8h, 0.5h to 7h, 0.5h to 6h, 0.5h to 5h, 0.5h to 4h, 0.5h to 3h, 0.5h to 2h, or 0.5h to 1h, etc.

[0169] In some embodiments, the silicon-based material includes at least one of silicon-carbon materials, silicon-oxygen materials, elemental silicon, and silicon alloys.

[0170] In the embodiments of this application, when the above-mentioned silicon-based materials are used, they can significantly improve the rate performance of the battery. Furthermore, using the above-mentioned materials as negative electrode active materials is beneficial to improving the energy density of lithium-ion batteries.

[0171] In some embodiments, the negative electrode active material may further include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, tin-based materials, and lithium titanate. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0172] In some embodiments, the silicon-based material in the negative electrode material layer accounts for 5% to 15% by mass, for example, 5%, 6%, 7%, 8%, 9%, 9.5%, 10%, 11%, 12%, 13%, 14%, 15%, etc.

[0173] When the mass percentage of silicon-based materials is greater than or equal to 5%, it can effectively improve the energy density of the battery; when its mass percentage is less than or equal to 15%, its expansion effect can be well suppressed, and even under high-rate charging conditions, lithium plating is not easily generated.

[0174] In some embodiments, the negative electrode sheet further includes a base coating layer disposed between the negative electrode current collector and the negative electrode material layer. The base coating layer can be a battery base coating layer known in the art, typically formed from a base coating slurry comprising a conductive agent, a binder, a dispersant, and deionized water. The conductive agent, binder, and dispersant can be conductive agents, binders, and dispersants known in the art for use in batteries. By further including a base coating layer, the adhesion between the negative electrode active material and the current collector can be increased, making the electrode sheet less prone to powder shedding or delamination during charging and discharging.

[0175] In some embodiments, the negative electrode current collector may be a metal foil or a current collector. For example, copper foil may be used as the metal foil. The current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0176] In some embodiments, the negative electrode material layer may optionally further include other binders. These other binders may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0177] In some embodiments, the negative electrode material layer may optionally further include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0178] In some embodiments, the negative electrode material layer may optionally also include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0179] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, conductive agent, conductive binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0180] [Positive electrode plate]

[0181] The positive electrode sheet includes a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector, the positive electrode material layer including a positive electrode active material.

[0182] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0183] In some embodiments, the positive current collector may be a metal foil or a current collector. For example, aluminum foil may be used as the metal foil. The current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0184] In some embodiments, when the battery cell is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, sodium transition metal oxides, polyanionic compounds, Prussian blue compounds, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon materials, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon materials, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon materials.

[0185] As an optional technical solution in this application, the transition metal in the sodium transition metal oxide can be at least one selected from Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. For example, the sodium transition metal oxide is Na. xMO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, 0 <x≤1。

[0186] As an optional technical solution in this application, the polyanionic compound can be a compound containing sodium ions, transition metal ions, or a tetrahedral (YO4) structure. n- A class of compounds with anionic units. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si; n represents (YO4). n- The price state.

[0187] Polyanionic compounds can also contain sodium ions, transition metal ions, or tetrahedral (YO4) ions. n- A class of compounds containing anionic units and halide anions. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si, and n represents (YO4). n- The valence state; the halogen can be at least one of F, Cl and Br.

[0188] Polyanionic compounds can also be sodium-containing tetrahedral (YO4) compounds. n- Anionic unit, polyhedral unit (ZO) y ) m+ And a class of compounds with optional halide anions. Y can be at least one of P, S, and Si, and n represents (YO4). n- The valence state; Z represents a transition metal, which can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; m represents (ZO) y ) m+ The valence state; the halogen can be at least one of F, Cl and Br.

[0189] Polyanionic compounds include, for example, NaFePO4, Na3V2(PO4)3, NaM'PO4F (where M' is one or more of V, Fe, Mn, and Ni) and Na3(VO y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0190] Prussian blue compounds can be a class of compounds containing sodium ions, transition metal ions, and cyanide ions (CN-). The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Examples of Prussian blue compounds include Na. a Me b Me'c (CN)6, wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co, and Zn, 0 <a≤2,0<b<1,0<c<1。

[0191] In some embodiments, the positive electrode material layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0192] In some embodiments, the positive electrode material layer may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0193] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0194] [Electrolytes]

[0195] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0196] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0197] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0198] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0199] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0200] [Isolation Component]

[0201] In some embodiments, the electrode assembly further includes a spacer disposed between the positive electrode and the negative electrode.

[0202] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0203] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a single component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0204] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0205] [Structure of the electrode assembly]

[0206] The electrode assembly can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0207] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0208] In some implementations, the electrode assembly is a stacked structure.

[0209] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0210] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0211] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0212] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0213] As an example, the separator can be set continuously, either by folding or rolling between any adjacent positive or negative electrode plates.

[0214] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0215] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0216] [shell]

[0217] In some embodiments, the battery cell may include a casing. The casing may be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum-plastic film, etc. In some embodiments, the casing may be a sealed structure or a non-sealed structure. As an example, when the casing is a non-sealed structure, the casing serves to protect the electrode assembly, and a sealing bag is included between the casing and the electrode assembly to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag may be a bag-shaped insulating component or an aluminum-plastic film. When the casing is a sealed structure, it is used to encapsulate components such as the electrode assembly and electrolyte.

[0218] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. This application does not have any particular limitations. For example, Figure 1 shows a prismatic battery cell 5 as an example.

[0219] In some embodiments, referring to FIG2, the housing includes an end cap 53 and a housing 51. The housing 51 has an opening, and the end cap 53 covers the opening. The housing 51 may have one or more openings. The end cap 53 may also be provided one or more times. The positive electrode, the negative electrode, and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within a receiving cavity formed by the housing 51 and the end cap 53. The electrolyte is immersed in the electrode assembly 52.

[0220] [Electrode terminals]

[0221] In some embodiments, at least one electrode terminal is provided on the housing, and the electrode terminal is electrically connected to the tab. The electrode terminal can be directly connected to the tab, or it can be indirectly connected to the tab through a current collector. The electrode terminal can be provided on the end cap or on the housing.

[0222] [Pressure relief mechanism]

[0223] In some embodiments, a pressure relief mechanism is provided on the casing. The pressure relief mechanism is used to release the internal gas of the battery cell.

[0224] As an example, the internal pressure or temperature of a battery cell is actuated to release the internal pressure or temperature when it reaches a predetermined threshold. When the internal pressure or temperature of the battery cell reaches the predetermined threshold, the pressure relief mechanism is activated or a weak structure in the pressure relief mechanism is broken, thereby forming an opening or channel for the internal pressure or temperature to be released. The threshold design varies depending on the design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell.

[0225] As an example, the pressure relief mechanism can be integrally molded with the housing.

[0226] As an example, the pressure relief mechanism can also be separately installed and connected to the housing.

[0227] The term "actuation" as used in this application refers to the activation or actuation of the pressure relief mechanism to a certain state, thereby releasing the internal pressure and temperature of the battery cell. The actions of the pressure relief mechanism may include, but are not limited to: movement of components within the mechanism to form an exhaust channel, rupture, breakage, tearing, or opening of at least a portion of the mechanism, etc. When the pressure relief mechanism is activated, the high-temperature, high-pressure substances inside the battery cell are discharged as waste from the activated portion. This method allows for pressure and temperature relief of the battery cell under controllable pressure or temperature, thereby preventing potentially more serious accidents.

[0228] In some embodiments, when the housing is a non-sealed structure, the pressure relief mechanism can be configured as a through hole for venting gas inside the battery cell.

[0229] The emissions from battery cells mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0230] Battery device

[0231] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0232] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0233] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties. Figure 3 shows a battery module 4 as an example. Referring to Figure 3, in battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other arbitrary way.

[0234] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0235] As an example, the battery cell assembly can be a battery module, which can be housed within a housing by fixing the battery module within the housing. Figures 4 and 5 show an example battery pack 1. Referring to Figures 4 and 5, the battery pack 1 can include a housing and multiple battery modules 4 disposed within the housing. The housing includes an upper housing 2 and a lower housing 3, with the upper housing 2 covering the lower housing 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery housing.

[0236] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0237] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0238] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0239] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0240] Electrical appliances

[0241] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft. Figure 6 shows an example electrical device. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0242] Example 1

[0243] This embodiment provides a lithium-ion battery cell, the preparation method of which is as follows, and the relevant parameters and test results are shown in Tables 1 to 3.

[0244] (I) Positive electrode plate

[0245] Nickel-cobalt-manganese LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM 622 Materials, conductive agent carbon black, and PVDF are mixed in a weight ratio of 97:2:1 and then uniformly dispersed in N-methylpyrrolidone (NMP) to obtain a positive electrode slurry. The positive electrode slurry is then uniformly coated onto the positive electrode current collector, and after drying, cold pressing, and slitting, a positive electrode sheet is obtained.

[0246] (II) Negative electrode plate

[0247] Preparation of conductive adhesive:

[0248] (1) Preparation of carbon nanotube (CNT) predispersant

[0249] 40g of single-walled carbon nanotubes (SWCNTs, with an average diameter of 2-3nm) were processed to a length of 5-10μm using a ball mill. The SWCNTs were added to a 400g carboxymethyl cellulose solution and heated to 65℃. Then, 0.8g of ammonium persulfate and monomers (100g of acrylic acid and 20g of acrylamide) were added dropwise to the solution over 3 hours. The solution was kept at a constant temperature for 1 hour to obtain a viscous product. After cooling to room temperature, the product was washed with water, centrifuged to remove impurities, and then diluted with deionized water to obtain a carbon nanotube pre-dispersion with a solid content of 1.0% and a viscosity of 23000mPa·s (25℃).

[0250] (2) Preparation of adhesive solution

[0251] 1.44 kg of acrylic acid, 0.83 kg of 2-acrylamide-2-methylpropanesulfonic acid, 0.95 kg of acrylonitrile, and 2.09 kg of 2-hydroxyethyl acrylate monomer were added to a three-necked flask equipped with a reflux condenser and a stirrer. 3 L of deionized water was added, followed by 2.39 g of ammonium persulfate. The mixture was reacted at 80°C with a rotation speed of 500 rpm for 8–12 hours. After the reaction was complete, a copolymer was obtained, which is the binder. The copolymer was diluted with deionized water to a binder solution with a solid content of 20 wt%, a viscosity of 15000 mPa·s, and a molecular weight of 750,000.

[0252] (3) Preparation of conductive binder dispersion

[0253] The conductive binder dispersion was prepared according to the following mass fractions: 33% carbon nanotube pre-dispersion, 18% binder solution, and the remainder being deionized water and LiOH aqueous solution for pH adjustment. The specific preparation method is as follows:

[0254] 4.75 kg of carbon nanotube pre-dispersion obtained in step (1) and 4.11 kg of deionized water were mixed at 80°C for 1 h. Then, 2.59 kg of binder solution obtained in step (2) was added to the system. After stirring at a constant temperature for 8 to 12 h, LiOH aqueous solution was added to adjust the pH value and a certain amount of deionized water was added to adjust the solid content. A black viscous solution with pH = 7 to 8, solid content of about 4%, and viscosity of 17500 mPa·s (25°C) was prepared, which is the conductive binder dispersion.

[0255] Preparation of primer current collector

[0256] Conductive carbon black (SP), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC-Na), and deionized water were mixed in a ratio of 1.5 kg: 0.13 kg: 0.13 kg: 8.24 kg at 1800 rpm and 25°C for 2 hours until homogeneous. The mixture was then filtered through a 200-mesh screen to obtain a primer slurry with a solid content of 15%–30% and a viscosity of 100 mPa·s–1000 mPa·s. This primer slurry was then gravure-coated onto a copper foil current collector substrate and dried to obtain a primer coating with a thickness of 2 μm.

[0257] Preparation of negative electrode sheet

[0258] The active material graphite, silicon oxide (SiOx, 0 < x < 2), carbon black, conductive binder dispersion, and thickener sodium carboxymethyl cellulose (CMC-Na) were stirred and mixed, then dispersed in deionized water. The mixture was stirred at 1800 r / min and 25℃ for 3 hours until homogeneous to obtain the negative electrode slurry. The mass ratio of graphite, silicon oxide, carbon black, conductive binder (based on solid content), and thickener in the negative electrode slurry was 88:9.5:0.5:1.5:0.5. The negative electrode slurry was uniformly coated onto a copper foil current collector coated with a primer slurry. After drying, cold pressing, and slitting, the negative electrode sheet was obtained.

[0259] (III) Electrolyte

[0260] Ethyl carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1. LiPF6 was then uniformly dissolved in this solution to obtain the electrolyte. The concentration of LiPF6 in the electrolyte was 1 mol / L.

[0261] (iv) Separating membrane

[0262] The separator is a 12μm thick porous polyethylene membrane.

[0263] (V) Lithium-ion batteries

[0264] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. They are then wound to obtain a bare cell. Tabs are welded onto the bare cell, which is then placed in an aluminum casing and baked at 80°C to remove moisture. Electrolyte is then injected and the casing is sealed, resulting in a non-charged battery. The non-charged battery then undergoes a series of processes including settling, hot and cold pressing, formation, shaping, and capacity testing to obtain the final battery product.

[0265] The prepared batteries were subjected to the following tests, and the test results are shown in Table 3:

[0266] 1. First effect

[0267] At 45℃, the battery was charged at a constant current of 0.02C to 3.75V, and the charging capacity C1 was recorded. After resting at 25℃ for 5 minutes, the battery was charged at a constant current of 1 / 3C to a voltage of 4.25V, and then charged at a constant voltage of 4.25V to a current of 0.05C, and the charging capacity C2 was recorded. After resting for 5 minutes, the battery was discharged at a constant current of 1 / 3C to a voltage of 2.8V, and the discharge capacity D0 was recorded. The initial efficiency (%) is D0 / (C1+C2).

[0268] 2. Ratio performance

[0269] At 25℃, the equivalent charging window test of 10%~80% SOC: At 25℃, the secondary battery is charged at a constant current of 1 / 3C to the charging cutoff voltage of 4.25V, then charged at a constant voltage to a current of 0.05C, left to stand for 5 minutes, and then discharged at a constant current of 1 / 3C to the discharge cutoff voltage of 2V. Its actual capacity is recorded as C0. Then, the battery was sequentially charged at a constant current of 0.5C0, 1C0, 1.5C0, 2C0, 2.5C0, 3C0, 3.5C0, 4C0, and 4.5C0 until the full battery charging cutoff voltage of 3.65V or the negative electrode cutoff potential of 0V (whichever comes first). After each charging, the battery was discharged at 1C0 until the full battery discharge cutoff voltage of 2.8V. The negative electrode potential corresponding to 80% SOC (State of Charge) was recorded at different charging rates. The rate-negative electrode potential curve was plotted, and the charging rate corresponding to the negative electrode potential of 0V at 80% SOC was obtained after linear fitting.

[0270] 3. Cyclic performance

[0271] At 25℃, the secondary battery was charged at a constant current of 1 / 3C to the charging cutoff voltage of 4.25V, then charged at a constant voltage to a current of 0.05C, allowed to stand for 5 minutes, and then discharged at a constant current of 1 / 3C to the discharge cutoff voltage of 2V. This constitutes one charge-discharge cycle, and the discharge capacity at this point is recorded as the discharge capacity of the battery in the first cycle. This charge-discharge cycle was repeated, and the capacity retention rate after 1000 cycles was calculated. Capacity retention rate = Discharge capacity after 1000 cycles / Discharge capacity in the first cycle × 100%.

[0272] Examples 2 to 23

[0273] The preparation method is basically the same as that in Example 1, but the specific parameters have been adjusted. The specific parameters and test results are shown in Tables 1 to 3. Among them, the conductive binder in Example 23 includes commercially available single-walled carbon nanotube slurry (OCSiAl Company, Russia, product 02HO17, solid content 1%) and the binder numbered 2-1 in Table 2.

[0274] Comparative Examples 1 to 2

[0275] The preparation method is basically the same as that in Example 1, but the specific parameters are adjusted as follows and in Tables 1 to 3. The test results are shown in Table 3.

[0276] The conductive adhesive of Comparative Example 1 includes polymer-grafted carbon nanotubes numbered 1-1 in Table 1 and a commercially available polyacrylic acid adhesive (Sichuan Yindile Technology Co., Ltd., LA136D, with a solid content of 6%).

[0277] The conductive binders in Comparative Example 2 included commercially available single-walled carbon nanotube slurry (OCSiAl Company, Russia, product 02HO17, 1% solids content) and commercially available polyacrylic acid binder (Sichuan Yindile Technology Co., Ltd., LA136D, 6% solids content).

[0278] Table 1. Composition of polymer-grafted carbon nanotubes

[0279] Table 2 Composition of Adhesive

[0280] Table 3. Composition and test results of conductive adhesives in the examples and comparative examples.

[0281] The results above show that the battery provided in this application not only has good cycle capacity retention but also excellent rate performance, making it suitable for fast charging. Replacing the binder in this application with a commercially available conventional product leads to a significant deterioration in battery performance. A comparison of Examples 1, 11-16, and Example 23 shows that polymer grafting onto single-walled carbon nanotubes further improves the battery's cycle performance.

[0282] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A battery cell, characterized in that, Includes positive electrode, separator, and negative electrode; The negative electrode sheet includes a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector; the negative electrode material layer includes a negative electrode active material and a conductive binder; The negative electrode active material includes silicon-based materials; The conductive binder includes an binder and a conductive agent; the conductive agent includes carbon nanotubes. The adhesive comprises structural unit (a) and structural unit (b); The structural unit (a) is derived from monomers selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups; The structural unit (b) is derived from monomers selected from the group consisting of any one or any combination of two or more monomers containing sulfonic acid groups, phosphate groups, sulfonate groups, or phosphate groups.

2. The battery cell as described in claim 1, characterized in that, The conductive agent is a polymer-grafted conductive agent, the polymer comprising a structural unit (a'), the structural unit (a') being derived from monomers selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups.

3. The battery cell according to claim 1 or 2, characterized in that, The monomer containing a carboxylic acid group has the structural formula shown in formula (I), and / or the monomer containing a carboxylate group has the structural formula shown in formula (I'). Among them, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C. 1-6 Alkyl, substituted C 1-6 The alkyl substituents are selected from at least one of amino, hydroxyl, and halogen groups; R4 is a direct bond, or a substituted or unsubstituted C. 1-6 Alkylene, C 1-6 alkylene amide group, C 1-6 alkeneoxy or C 1-6 alkylene ester group, the substituted C 1-6 The substituents of the alkylene group are selected from at least one of amino, hydroxyl, and halogen groups; M is selected from ammonium ions or metal ions.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The monomer containing the sulfonic acid group has the structural formula shown in formula (II), and / or the monomer containing the sulfonate group has the structural formula shown in formula (II'). Among them, R5, R6, and R7 are each independently selected from H, substituted or unsubstituted C. 1-6 Alkyl, substituted C 1-6 The alkyl substituents are selected from at least one of amino, hydroxyl, and halogen groups; R8 is a direct bond, or a substituted or unsubstituted C. 1-6 Alkylene, C 1-6 alkylene amide group, C 1-6 alkeneoxy or C 1-6 alkylene ester group, the substituted C 1-6 The substituents of the alkylene group are selected from at least one of amino, hydroxyl, and halogen groups; M is selected from ammonium ions or metal ions.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The monomer containing the phosphate group has the structural formula shown in formula (III), and / or the monomer containing the phosphate group has the structure shown in formula (III'). Among them, R9, R 10 R 11 Each is independently selected from H, substituted or unsubstituted C. 1-6 Alkyl, substituted C 1-6 The alkyl substituents are selected from at least one of amino, hydroxyl, and halogen groups; R 12 For direct bonding, or for substituted or unsubstituted C 1-6 Alkylene, C 1-6 alkylene amide group, C 1-6 alkeneoxy or C 1-6 alkylene ester group, the substituted C 1-6 The substituents of the alkylene group are selected from at least one of amino, hydroxyl, and halogen groups; M is selected from ammonium ions or metal ions.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The monomer containing a carboxylic acid group includes at least one of the following: acrylic acid, methacrylic acid, butenoic acid, 3,3-dimethacrylic acid, 2-ethylacrylic acid, 3-propylacrylic acid, trimethacrylic acid, 3-butylacrylic acid, 2-butylacrylic acid, 2-pentylacrylic acid, 2,3-diethylacrylic acid, 3,3-diethylacrylic acid, 2-methyl-3-pentylacrylic acid, 3-methyl-3-pentylacrylic acid, 3-methyl-3-propylacrylic acid, 3-methyl-3-hexylacrylic acid, wherein the monomer containing a carboxyl salt group is the corresponding lithium salt of the monomer containing the carboxylic acid group; and / or, The monomer containing a sulfonic acid group includes at least one of the following: vinyl sulfonic acid, allyl sulfonic acid, 2-methylallyl sulfonic acid, and 2-acrylamide-2-methylpropanesulfonic acid, wherein the monomer containing a sulfonate group is the corresponding lithium salt of the monomer containing the sulfonic acid group; and / or, The monomer containing a phosphate group includes at least one of the following: vinylphosphonic acid, 2-methylvinylphosphonic acid, 2-ethylvinylphosphonic acid, allylphosphonic acid, and cis-propenylphosphonic acid, wherein the monomer containing a phosphate group is the corresponding lithium salt of the monomer containing the phosphate group.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The adhesive further includes structural unit (c); and / or, the polymer further includes structural unit (c'); The structural unit (c) and structural unit (c') are each independently derived from any one or any combination of two or more monomers selected from the group consisting of monomers containing amide groups, monomers containing nitrile groups, monomers containing hydroxyl groups, monomers containing ester groups, and fluorine-containing monomers.

8. The battery cell as described in claim 7, characterized in that, The monomer containing an amide group includes at least one of the following: acrylamide, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-n-propylmethacrylamide, N-isopropylmethacrylamide, N-n-butylmethacrylamide, N-isobutylmethacrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N-hydroxymethylmethacrylamide, N,N-dihydroxymethylmethacrylamide, N-hydroxymethylacrylamide, 2-acrylamido-2-methylpropanesulfonic acid; and / or, The monomer containing a nitrile group includes at least one of the following: acrylonitrile, α-chloroacrylonitrile, α-bromoacrylonitrile, α-fluoroacrylonitrile, methacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-n-hexylacrylonitrile; and / or, The hydroxyl-containing monomer comprises at least one of the following: 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, allyl alcohol; and / or, The monomer containing the ester group includes at least one of the following: 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, 3,5,5-trimethylhexyl acrylate, 2-ethylhexyl acrylate; and / or, The fluorinated monomer includes at least one of the following: C having at least one fluorine substitution. 1-6 Alkyl acrylates, C having at least one fluorine substitution 1-6 Alkyl methacrylates.

9. The battery cell as described in claim 7 or 8, characterized in that, The structural unit (c) is derived from a combination of monomers including the following groups: monomers containing amide groups, monomers containing nitrile groups, monomers containing hydroxyl groups, and monomers containing ester groups.

10. The battery cell according to any one of claims 1 to 9, characterized in that, In the adhesive, the mass fraction of structural unit (a) is 20%–70%, and the mass fraction of structural unit (b) is 5%–50%; and / or, In the polymer-grafted conductive agent, the mass fraction of the structural unit (a') is 20% to 80%.

11. The battery cell according to any one of claims 7 to 10, characterized in that, In the adhesive, the structural unit (c) has a mass fraction of 0.1% to 70%; and / or, In the polymer-grafted conductive agent, the mass fraction of the structural unit (c') is 5% to 40%.

12. The battery cell according to any one of claims 1 to 11, characterized in that, The mass ratio of the adhesive to the conductive agent is 2 to 100.

13. The battery cell according to any one of claims 1 to 12, characterized in that, The adhesive has a weight-average molecular weight of 500,000 to 2,500,000; and / or, The weight-average molecular weight of the polymer is 2000 to 30000.

14. The battery cell according to any one of claims 1 to 13, characterized in that, The carbon nanotubes include at least one of single-walled carbon nanotubes, oligo-walled carbon nanotubes, or multi-walled carbon nanotubes; and / or, The length of the carbon nanotubes is 0.5–30 μm.

15. The battery cell according to any one of claims 1 to 14, characterized in that, The silicon-based material includes at least one of silicon-carbon materials, silicon-oxygen materials, elemental silicon, and silicon alloys.

16. The battery cell according to any one of claims 1 to 15, characterized in that, In the negative electrode material layer, the silicon-based material accounts for 5% to 15% of the total mass; and / or, The conductive adhesive accounts for 0.5% to 2% of the total mass.

17. A conductive adhesive, characterized in that, The conductive binder includes an binder and a conductive agent; the conductive agent includes carbon nanotubes. The adhesive comprises structural unit (a) and structural unit (b); The structural unit (a) is derived from monomers selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups; The structural unit (b) is derived from monomers selected from the group consisting of any one or any combination of two or more monomers containing sulfonic acid groups, phosphate groups, sulfonate groups, or phosphate groups.

18. The conductive adhesive as claimed in claim 17, characterized in that, The conductive agent is a polymer-grafted conductive agent, the polymer comprising a structural unit (a'), the structural unit (a') being derived from monomers selected from the group consisting of any one or a combination of two of the following: monomers containing carboxylic acid groups, monomers containing carboxylate groups.

19. The conductive adhesive as claimed in claim 17 or 18, characterized in that, The adhesive further includes structural unit (c); and / or, the polymer includes structural unit (c'); The structural unit (c) and structural unit (c') are each independently derived from any one or any combination of two or more monomers selected from the group consisting of monomers containing amide groups, monomers containing nitrile groups, monomers containing hydroxyl groups, monomers containing ester groups, and fluorine-containing monomers.

20. The conductive adhesive according to any one of claims 17 to 19, characterized in that, In the adhesive, the mass fraction of structural unit (a) is 20%–70%, and the mass fraction of structural unit (b) is 5%–50%; and / or, In the polymer-grafted conductive agent, the mass fraction of the structural unit (a') is 20% to 80%.

21. The conductive adhesive according to any one of claims 19-20, characterized in that, In the adhesive, the structural unit (c) has a mass fraction of 0.1% to 70%; and / or, In the polymer-grafted conductive agent, the mass fraction of the structural unit (c') is 5% to 40%.

22. The conductive adhesive according to any one of claims 17 to 21, characterized in that, The mass ratio of the adhesive to the conductive agent is 2 to 100.

23. The conductive adhesive according to any one of claims 17 to 22, characterized in that, At 25°C, the viscosity of an aqueous solution of a binder with a solid content of 15%–25% is 15000–31000 mPa·s; and / or, At 25°C, the viscosity of an aqueous solution of a conductive agent with a solid content of 0.7%–1.5% is 8000–35000 mPa·s; and / or, At 25°C, the viscosity of an aqueous solution of a conductive adhesive with a solid content of 1.5% to 10% is 8000 to 35000 mPa·s.

24. A battery device, characterized in that, Includes the battery cell according to any one of claims 1 to 16.

25. An electrical appliance, characterized in that, It includes the battery cell according to any one of claims 1 to 16, or the battery device according to claim 24.

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