Bonding composition, negative plate, preparation method of negative plate, battery and electric device

Abstract

The invention relates to a bonding composition, a negative plate, a preparation method of the negative plate, a battery and an electric device. The bonding composition comprises a functional polymer containing a functional group and a micromolecular tertiary amine compound containing a functional group, wherein the functionality of the functional group in the micromolecular tertiary amine compound is greater than or equal to 2; the functional group in the functional polymer and the functional group in the micromolecular tertiary amine compound meet at least one of the following conditions: (1) the functional group and the functional group can form a hydrogen bond; and (2) the functional group and the functional group can be subjected to chemical reaction. When the material is used for preparing batteries, the cycling stability of the batteries can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a bonding composition, a negative electrode sheet and a preparation method thereof, a battery and an electrical device. Background Art

[0002] Secondary batteries are becoming increasingly popular due to their clean and renewable characteristics, and have been widely used in many fields such as consumer electronics, electric vehicles, and energy storage.

[0003] As the application of secondary batteries expands, people are demanding higher performance from them, such as high energy density and long cycle life. However, during the cycling of a battery cell, as active ions such as lithium ions are continuously embedded in the negative electrode material, the volume of the negative electrode sheet gradually expands. This is especially true when using high-capacity silicon-based materials (theoretical capacity can reach 4200mAh / g) as the negative electrode material. The silicon volume expansion is even greater, making it more likely that silicon particles will shatter and fall off the current collector during charge and discharge, leading to a loss of electrical connection. This results in a decrease in the cycling stability of the secondary battery, making it difficult to meet the increasingly stringent performance requirements for secondary batteries.

[0004] Therefore, traditional technologies still need to be further improved. Summary of the Invention

[0005] Based on this, it is necessary to provide a bonding composition, a negative electrode sheet and a preparation method thereof, a battery and an electrical device, in order to improve the cycle stability of the battery.

[0006] In a first aspect of the present application, a bonding composition is provided, comprising: a functional polymer containing a functional group and a small molecule tertiary amine compound containing a functional group, wherein the functionality of the functional group in the small molecule tertiary amine compound is ≥2;

[0007] The functional group in the functional polymer and the functional group in the small molecule tertiary amine compound meet at least one of the following conditions:

[0008] (1) The functional group and the functional group can form a hydrogen bond;

[0009] (2) The functional group and the functional group can undergo chemical reaction.

[0010] The above-mentioned bonding composition includes a functional polymer containing a functional group and a small molecule tertiary amine compound containing a functional group, wherein the functional group and the functional group can form a hydrogen bond or can directly react chemically. On the one hand, the functionality of the functional group in the small molecule tertiary amine compound is ≥2, so that the functional group in one molecule of the small molecule tertiary amine compound can be connected with the functional groups on at least two molecular chains of the functional polymer by forming a hydrogen bond or directly reacting with at least one of them, thereby forming a cross-linked network bonding material. When used to prepare a negative electrode sheet of a battery, it can improve the bonding with the negative electrode active material and has good mechanical properties, thereby inhibiting the expansion of the negative electrode active material and causing sliding between the negative electrode active material particles during the cycle, thereby reducing the probability of electrical contact loss during battery recycling. On the other hand, the small molecule tertiary amine compound contains a tertiary amine structure. When used to prepare a negative electrode sheet, it can induce and participate in the formation of a functional film layer (SEI film) during the cyclic charge and discharge process, generating a special nitrogen-containing component to optimize the composition of the functional film layer, and the nitrogen atom has a lone pair of electrons, which can accelerate Li + The diffusion and transport of active ions further improve the cycle stability of the battery.

[0011] In some embodiments, the mass ratio of the functional polymer to the small molecule tertiary amine compound is (1-19):1.

[0012] In some embodiments, the mass ratio of the functional polymer to the small molecule tertiary amine compound is (7-10):1.

[0013] By regulating the mass ratio of the functional polymer and the small molecule tertiary amine compound, more tertiary amine nitrogen atoms are introduced while maintaining good adhesion to the negative electrode material.

[0014] In some embodiments, the functional group and the functional group are independently selected from at least one of hydroxyl, carboxyl amide and primary amine.

[0015] In some embodiments, the small molecule tertiary amine compound is represented by formula (A):

[0016]

[0017] Among them, each R a are independently selected from an alkyl group having 1 to 5 carbon atoms, an aromatic group having 6 to 10 ring atoms, a heteroaromatic group having 5 to 10 ring atoms, a group substituted by the functional group or -N(R b )2 substituted alkyl with 1 to 5 carbon atoms, heteroaromatic group with 5 to 10 ring atoms substituted by the functional group, aromatic group with 6 to 10 ring atoms substituted by the functional group, cyano group, halogen, and at least two R a Selected from the functional group or -N(Rb )2-substituted alkyl group having 1 to 5 carbon atoms, heteroaromatic group having 5 to 10 ring atoms substituted by the functional group, or aromatic group having 6 to 10 ring atoms substituted by the functional group.

[0018] Each R b Each of them is independently selected from any one of an alkyl group having 1 to 5 carbon atoms substituted by the functional group, a heteroaromatic group having 5 to 10 ring atoms substituted by the functional group, and an aromatic group having 6 to 10 ring atoms substituted by the functional group.

[0019] In some embodiments, the small molecule tertiary amine compound includes at least one of nitrilotriacetic acid, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid.

[0020] In some embodiments, the functional polymer satisfies at least one of the following conditions (1) to (2):

[0021] (1) The functional polymer includes a polymer of formula (I):

[0022]

[0023] wherein R1 and R2 are independently selected from H, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a cyano group, a halogen group, a substituted or unsubstituted aromatic group having 6 to 10 ring atoms, a substituted or unsubstituted heteroaromatic group having 5 to 10 ring atoms, and any one of the functional groups, and at least one R1 or at least one R2 is selected from the functional groups, L is selected from a single bond or oxygen; n is the degree of polymerization;

[0024] (2) The functional polymer is a water-soluble polymer.

[0025] In some embodiments, the functional polymer includes at least one of acrylic polymer, polyvinyl alcohol, polyethylene glycol, and polyacrylamide.

[0026] In a second aspect of the present application, a negative electrode sheet is provided, comprising a current collector and a negative electrode active layer provided on at least one surface of the current collector, wherein the negative electrode active layer comprises a negative electrode active material and a binding material, wherein the binding material satisfies at least one of the following conditions:

[0027] (1) The bonding material includes the bonding composition of the first aspect;

[0028] (2) The bonding material includes a cross-linked polymer formed by a chemical reaction between the functional polymer in the bonding composition of the first aspect and the small molecule tertiary amine compound, and the reaction sites of the chemical reaction include the functional groups in the functional polymer and the functional groups in the small molecule tertiary amine compound.

[0029] In the above-mentioned negative electrode, the binding material in the negative electrode active layer includes at least one of the above-mentioned binding composition or the cross-linked polymer formed by the above-mentioned binding composition. On the one hand, the functional groups in the small molecule tertiary amine compound can be connected with the functional groups on at least two molecular chains of the functional polymer by forming hydrogen bonds or undergoing at least one of chemical reactions, thereby forming a cross-linked network binding material, thereby improving the adhesion between the binding material and the negative electrode material, and having good mechanical properties, thereby inhibiting the expansion of the negative electrode material and causing sliding between the negative electrode material particles during the cycle, thereby reducing the probability of electrical contact loss during battery recycling; on the other hand, the small molecule tertiary amine compound contains a tertiary amine structure, which can induce and participate in the formation of a functional film layer (SEI film) during the cyclic charge and discharge process, generating a special nitrogen-containing component to optimize the composition of the functional film layer, and the nitrogen atom has a lone pair of electrons, which can accelerate Li + The diffusion and transport of active ions further improve the cycle stability of the battery.

[0030] In some embodiments, in the negative electrode active layer, the mass proportion of the binding material is 1% to 20%.

[0031] In some embodiments, the negative electrode sheet satisfies at least one of the following conditions (1) to (3):

[0032] (1) The negative electrode active material includes at least one of a silicon-based active material and a carbon-based active material;

[0033] (2) In the negative electrode active layer, the mass proportion of the negative electrode active material is 60% to 99%;

[0034] (3) The negative electrode active layer further includes a conductive agent, and the conductive agent accounts for 0.05% to 30% by mass in the negative electrode active layer.

[0035] In a third aspect of the present application, a method for preparing a negative electrode sheet is provided, comprising the following steps:

[0036] A negative electrode active slurry is used to form a negative electrode active layer on at least one side of the current collector; the negative electrode active slurry includes a negative electrode active material and a binding material;

[0037] The bonding material satisfies at least one of the following conditions:

[0038] (1) The bonding material includes the bonding composition of the first aspect;

[0039] (2) The bonding material includes a cross-linked polymer formed by a chemical reaction between the functional polymer in the bonding composition of the first aspect and the small molecule tertiary amine compound, and the reaction sites of the chemical reaction include the functional groups in the functional polymer and the functional groups in the small molecule tertiary amine compound.

[0040] In a fourth aspect of the present application, a battery is provided, comprising the negative electrode sheet of the second aspect or the negative electrode sheet prepared by the method for preparing the negative electrode sheet of the third aspect.

[0041] In some embodiments, the negative electrode active layer further comprises a functional interface film, the components of which include C3N - and CNO - At least one of .

[0042] The tertiary amine structure introduced into the bonding material can induce and participate in the formation of the functional film layer (also known as SEI film) during the charge and discharge process, generating a special nitrogen-containing component: C3N - and CNO - , in order to optimize the composition of the functional film layer, and the nitrogen atom has a lone pair of electrons, which can accelerate the Li + The diffusion and transport of active ions further improve the cycle stability of the battery.

[0043] In some embodiments, the functional interface film is subjected to a TOF-SIMS test to obtain a normalized secondary ion mass spectrum, and the secondary ion mass spectrum satisfies at least one of the following conditions (1) to (2):

[0044] (1)C3N - The relative intensity ratio range of the corresponding characteristic peak R1 is: 0<R1≤0.3%;

[0045] (2) CNO - The relative intensity ratio range R2 of the corresponding characteristic peak is: 0.3%≤R2≤2%.

[0046] In some embodiments, the negative electrode sheet satisfies at least one of the following conditions (1) to (2):

[0047] (1) The thickness H of the functional interface film is: 0<H≤60nm;

[0048] (2) The functional interface film is supported on at least a portion of the surface of at least a portion of the negative electrode active material.

[0049] In some embodiments, the functional interface film further comprises LiF, CHO2 - , Li2CO3, Li2O, rOCO2Li, r is Li or an alkyl group.

[0050] In a fifth aspect of the present application, an electrical device is provided, comprising the battery according to the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0052] Figure 1 Schematic diagram of the mechanism of action of the bonding composition in one embodiment of the present application;

[0053] Figure 2 is a schematic diagram of one embodiment of a battery cell;

[0054] Figure 3 yes Figure 2 Exploded view of

[0055] Figure 4 is a schematic diagram of one embodiment of a battery pack;

[0056] Figure 5 yes Figure 4 Exploded view of

[0057] Figure 6 is a schematic diagram of an embodiment of an electrical device using a battery as a power source;

[0058] Figure 7 This is an electron microscope image of the negative electrode active layer prepared in Example 1.

[0059] Description of reference numerals:

[0060] 1. Battery pack; 2. Upper box; 3. Lower box; 4. Battery cell; 41. Shell; 42. Electrode assembly; 43. Cover; 5. Electrical device. DETAILED DESCRIPTION

[0061] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0062] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0063] In this application, the term "alkyl" refers to a group formed when an alkane loses a hydrogen atom, such as methane losing a hydrogen atom to form a methyl group.

[0064] In the present application, the number of carbon atoms in the "alkyl group having 1 to 5 carbon atoms" may be 1 to 5, including 1, 2, 3, 4, and 5. Non-limiting examples include methane, ethyl, and n-propyl.

[0065] In the present application, the halogen group includes chlorine, fluorine, bromine, and iodine.

[0066] In this application, "aryl" refers to a hydrocarbon group containing at least one aromatic ring, including non-fused-ring aromatic groups and fused-ring aromatic groups. A fused-ring aromatic group is a group formed by linking two or more aromatic rings through two common adjacent ring atoms, i.e., a fused ring.

[0067] Aromatic ring refers to a cyclic hydrocarbon compound with aromatic properties: that is, a hydrocarbon compound with a cyclic closed-ring conjugated system.

[0068] In the present application, "heteroaromatic group" refers to a group formed when a hydrocarbon compound containing a heteroatom loses a hydrogen atom and has a cyclic closed-ring conjugated system; further, the type of heteroatom can be N, O, P, S, etc.

[0069] In this application, the term "ring atoms" refers to the number of atoms bonded to form a ring. When a ring is substituted with a substituent, the atoms contained in the substituent are not included in the ring atoms. The term "ring atoms" used below applies unless otherwise specified. For example, a benzene ring has 6 ring atoms, and a naphthalene ring has 10 ring atoms.

[0070] In the present application, “small molecule” refers to a compound with a relative molecular weight less than or equal to 1000, and further refers to a compound with a relative molecular weight less than or equal to 500.

[0071] In conventional technology, in order to suppress the expansion of negative electrode materials, a negative electrode sheet is often prepared by using a binder that can form a three-dimensional network structure with strong binding force.

[0072] However, relying solely on a binder to form a three-dimensional network structure to bind the negative electrode active material has limited effect on improving battery cycling stability, especially in silicon-based negative electrode systems with large expansion, making it difficult to meet the increasingly stringent requirements for secondary battery performance. Further research has found that tertiary amine structures containing nitrogen atoms can induce and participate in the formation of the SEI film, affecting the battery's cycling stability.

[0073] Based on this, after a lot of experimental research, the technical solution of this application was obtained.

[0074] In one embodiment of the present application, a bonding composition is provided, comprising: a functional polymer containing a functional group and a small molecule tertiary amine compound containing a functional group, wherein the functionality of the functional group in the small molecule tertiary amine compound is ≥2.

[0075] The functional group in the functional polymer and the functional group in the small molecule tertiary amine compound meet at least one of the following conditions:

[0076] (1) Functional groups can form hydrogen bonds;

[0077] (2) Functional groups can undergo chemical reactions.

[0078] The above-mentioned bonding composition includes a functional polymer containing a functional group and a small molecule tertiary amine compound containing a functional group, wherein the functional group and the functional group can form a hydrogen bond or can directly undergo a chemical reaction. On the one hand, the functionality of the functional group in the small molecule tertiary amine compound is ≥2, so that the functional group in one molecule of the small molecule tertiary amine compound can be connected with at least two functional groups on two molecular chains of the functional polymer by forming a hydrogen bond or directly undergoing a chemical reaction, thereby forming a cross-linked network bonding material. When used to prepare a negative electrode sheet of a battery, it can improve the bonding with the negative electrode active material and has good mechanical properties, thereby inhibiting the expansion of the negative electrode active material and causing sliding between the negative electrode active material particles during the cycle, thereby reducing the probability of electrical contact loss during battery recycling. On the other hand, the small molecule tertiary amine compound contains a tertiary amine structure. When used to prepare a negative electrode sheet, it can induce and participate in the formation of a functional film layer (SEI film) during the cyclic charge and discharge process, generating a special nitrogen-containing component to optimize the composition of the functional film layer, and the nitrogen atom has a lone pair of electrons, which can accelerate Li + The diffusion and transport of active ions further improve the cycle stability of the battery.

[0079] Furthermore, the types of multiple functional groups in the same small molecule tertiary amine compound may be the same or different.

[0080] It should be noted that the functionality of the functional groups in the small molecule tertiary amine compound refers to the number of functional groups contained in one molecule of the small molecule tertiary amine compound.

[0081] In some embodiments, the functional group and the functional group are independently selected from at least one of hydroxyl, carboxyl, amide and primary amine groups.

[0082] It can be understood that the functional groups and functional groups can be the same groups that can form hydrogen bonds with each other, such as carboxyl groups and carboxyl groups, primary amine groups and primary amine groups, etc., or they can be the same groups that can undergo chemical reactions with each other, such as hydroxyl groups and hydroxyl groups, or they can be different groups that can form hydrogen bonds or undergo chemical reactions, such as hydroxyl groups and amine groups that can form hydrogen bonds, and carboxyl groups and hydroxyl groups that can undergo condensation chemical reactions. The specific type of chemical reaction may depend on the type of functional groups and functional groups, including but not limited to: at least one of: esterification reaction, dehydration condensation reaction between hydroxyl groups and hydroxyl groups, and acylation reaction between carboxyl groups and primary amine groups.

[0083] Please refer to the attached Figure 1 , Figure 1 This is a schematic diagram of the three-dimensional network structure formation using a small molecule tertiary amine compound as nitrilotriacetic acid (NTA) and a functional polymer as polyacrylic acid (PAA) as an example. The two carboxyl groups in the nitrilotriacetic acid form hydrogen bonds with the carboxyl groups on the two polyacrylic acid (PAA) chains ( Figure 1 The “…” indicates hydrogen bonding) to form a cross-linked structure.

[0084] Please continue to refer to Figure 1 If the functional polymer contains a functional group that can react chemically with the functional group in the small molecule tertiary amine compound, the functional group and the functional group can further react to form a chemical crosslink. For example, when the small molecule tertiary amine compound is nitrilotriacetic acid (NTA) and the functional polymer is polyethylene glycol, the carboxyl group on the nitrilotriacetic acid and the hydroxyl group in the polyethylene glycol can further undergo condensation esterification to form a chemical crosslink, and still obtain Figure 1 The cross-linked structure is shown.

[0085] In some embodiments, the mass ratio of the functional polymer to the small molecule tertiary amine compound is (1-19):1.

[0086] In some embodiments, the mass ratio of the functional polymer to the small molecule tertiary amine compound is (7-10):1.

[0087] By regulating the mass ratio of the functional polymer and the small molecule tertiary amine compound, more tertiary amine nitrogen atoms are introduced while maintaining good adhesion to the negative electrode material.

[0088] In the above "(1~19):1", the specific values ​​include the minimum and maximum values ​​of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and the following point values: 19:1, 18:1, 17:1, 16:1, 15:1, 14:1, 13:1, 12:1, 11:1, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1; or a range consisting of any two values.

[0089] In some embodiments, the small molecule tertiary amine compound is represented by formula (A):

[0090]

[0091] Among them, each R a are independently selected from an alkyl group having 1 to 5 carbon atoms, an aromatic group having 6 to 10 ring atoms, a heteroaromatic group having 5 to 10 ring atoms, a group substituted by the functional group or -N(R b )2 substituted alkyl with 1 to 5 carbon atoms, heteroaromatic group with 5 to 10 ring atoms substituted by the functional group, aromatic group with 6 to 10 ring atoms substituted by the functional group, cyano group, halogen, and at least two R a Selected from the functional group or -N(R b )2 substituted alkyl group having 1 to 5 carbon atoms, heteroaromatic group having 5 to 10 ring atoms substituted by the functional group, or aromatic group having 6 to 10 ring atoms substituted by the functional group;

[0092] Each R b Each of them is independently selected from any one of an alkyl group having 1 to 5 carbon atoms substituted by the functional group, a heteroaromatic group having 5 to 10 ring atoms substituted by the functional group, and an aromatic group having 6 to 10 ring atoms substituted by the functional group.

[0093] In some embodiments, each R b Each is independently selected from any one of an alkyl group having 2 to 4 carbon atoms substituted by a functional group, a heteroaromatic group having 5 to 8 ring atoms substituted by a functional group, and an aromatic group having 6 to 8 ring atoms substituted by a functional group.

[0094] In some embodiments, at least two R a Selected from functional groups or -N(R b )2-substituted chain alkyl group having 1 to 4 carbon atoms, heteroaromatic group having 5 to 8 ring atoms substituted by the functional group, or aromatic group having 6 to 8 ring atoms substituted by the functional group.

[0095] In some embodiments, at least two R a are independently selected from the functional group or -N(R b )2-substituted chain alkyl having 1 to 3 carbon atoms.

[0096] In some embodiments, the three R a are independently selected from the functional group or -N(R b )2-substituted chain alkyl having 1 to 3 carbon atoms.

[0097] In some embodiments, each R b Each is independently selected from a chain alkyl group having 2 to 5 carbon atoms substituted with a functional group.

[0098] In some embodiments, each R b Each is independently selected from a chain alkyl group having 2 to 4 carbon atoms substituted with a functional group.

[0099] In some embodiments, the small molecule tertiary amine compound includes at least one of nitrilotriacetic acid, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid.

[0100] In some embodiments, the functional polymer comprises a polymer of formula (I):

[0101]

[0102] Wherein, R1 and R2 are independently selected from H, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a cyano group, a halogen group, a substituted or unsubstituted aromatic group having 6 to 10 ring atoms, a substituted or unsubstituted heteroaromatic group having 5 to 10 ring atoms and any one of the functional groups, and at least one R1 or at least one R2 is selected from the functional groups, L is selected from a single bond or oxygen; and n is the degree of polymerization.

[0103] It can be understood that the above-mentioned [] represents a polymerization unit, n is the degree of polymerization, and when R1 or R2 in multiple polymerization units is selected from functional groups, the specific types may be the same or different.

[0104] In some embodiments, R1 and R2 are independently selected from any one of H, a chain alkyl group having 1 to 5 carbon atoms, a cyano group, a halogen, a chain alkyl group having 1 to 5 carbon atoms substituted by a halogen, an aromatic group having 6 to 10 ring atoms, a heteroaromatic group having 5 to 10 ring atoms, and a functional group.

[0105] In some embodiments, R1 and R2 are independently selected from any one of H, a chain alkyl group having 1 to 5 carbon atoms, a cyano group, a halogen, a chain alkyl group having 1 to 5 carbon atoms substituted by a halogen, an aromatic group having 6 to 8 ring atoms, a heteroaromatic group having 5 to 8 ring atoms, and a functional group.

[0106] In some embodiments, R1 and R2 are independently selected from any one of H, a chain alkyl group with 1 to 3 carbon atoms, a cyano group, a halogen, a chain alkyl group with 1 to 3 carbon atoms substituted by a halogen, an aromatic group with 6 to 8 ring atoms, and a functional group.

[0107] In some embodiments, the functional polymer includes at least one of acrylic polymer, polyvinyl alcohol, polyethylene glycol, and polyacrylamide.

[0108] In one embodiment of the present application, a negative electrode sheet is provided. The negative electrode sheet includes a current collector and a negative electrode active layer provided on at least one surface of the current collector. The negative electrode active layer includes a negative electrode active material and a binding material. The binding material satisfies at least one of the following conditions:

[0109] (1) The bonding material includes the bonding composition of the first aspect.

[0110] (2) The bonding material includes a cross-linked polymer formed by a chemical reaction between the functional polymer in the bonding composition of the first aspect and the small molecule tertiary amine compound, and the reaction sites of the chemical reaction include the functional groups in the functional polymer and the functional groups in the small molecule tertiary amine compound.

[0111] In the above-mentioned negative electrode, the binding material in the negative electrode active layer includes at least one of the above-mentioned binding composition or the cross-linked polymer formed by the above-mentioned binding composition. On the one hand, the functional groups in the small molecule tertiary amine compound can be connected with the functional groups on at least two molecular chains of the functional polymer by forming hydrogen bonds or undergoing at least one of chemical reactions, thereby forming a cross-linked network binding material, thereby improving the adhesion between the binding material and the negative electrode material, and having good mechanical properties, thereby inhibiting the expansion of the negative electrode material and causing sliding between the negative electrode material particles during the cycle, thereby reducing the probability of electrical contact loss during battery recycling; on the other hand, the small molecule tertiary amine compound contains a tertiary amine structure, which can induce and participate in the formation of a functional film layer (SEI film) during the cyclic charge and discharge process, generating a special nitrogen-containing component to optimize the composition of the functional film layer, and the nitrogen atom has a lone pair of electrons, which can accelerate Li + The diffusion and transport of active ions further improve the cycle stability of the battery.

[0112] It can be understood that: when the functional groups in the functional polymer and the functional groups in the small molecule tertiary amine compound can only form hydrogen bonds, no chemical reaction occurs between the components of the bonding composition, and the original chemical structure remains. Only hydrogen bonds will be formed between the functional groups to form a network structure. If the functional groups in the functional polymer and the functional groups in the small molecule tertiary amine compound can undergo chemical reactions, a chemically cross-linked cross-linked polymer will be formed. Furthermore, the functional groups in a molecule of small molecule tertiary amine compound can be the same or different, and the types of multiple functional groups in the functional polymer can also be the same or different. Then, the bonding material can meet the above two conditions at the same time, and when the functional groups in a molecule of small molecule tertiary amine compound are different, they can form hydrogen bonds and chemical cross-links with multiple functional groups respectively, that is, hydrogen bonds can be formed simultaneously in the cross-linked polymer.

[0113] In some embodiments, in the negative electrode active layer, the binder accounts for 1% to 20% by mass.

[0114] In the above "1% to 20%", the specific values ​​include the minimum and maximum values ​​of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and the following point values: 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%; or a range consisting of any two values.

[0115] In some embodiments, the negative electrode active material may be a commonly used negative electrode active material in this application.

[0116] In some embodiments, the negative electrode active material includes at least one of a silicon-based active material and a carbon-based active material.

[0117] In any embodiment of the present application, the above-mentioned negative electrode active material includes at least one of mesocarbon microbeads, graphite, glassy carbon, carbon nanotubes, carbon-carbon composite materials, carbon fibers, hard carbon, soft carbon, silicon-based materials, tin-based materials, magnesium-based materials or iron-based materials.

[0118] Optionally, specific examples of the above-mentioned negative electrode active materials include, but are not limited to: at least one of mesophase carbon microbeads, natural graphite, artificial graphite, graphene, glassy carbon, carbon nanotubes, carbon fibers, hard carbon, soft carbon, iron oxide, tin oxide, silicon oxide, magnesium oxide, silicon-carbon composites, lithium metal or lithium metal alloys.

[0119] In some embodiments, in the negative electrode active layer, the mass proportion of the negative electrode active material is 60% to 99%.

[0120] In some embodiments, the negative electrode active layer further includes a conductive agent.

[0121] In some embodiments, the conductive agent accounts for 0.05% to 30% by mass in the negative electrode active layer.

[0122] In any embodiment of the present application, the conductive agent may be any commonly used conductive agent in the art, including but not limited to at least one of graphite, carbon nanotubes, nanofibers, carbon black, or graphene. Specifically, the conductive agent may be selected from at least one of SP, KS-6, acetylene black, branched Ketjen black ECP, SFG-6, vapor-grown carbon fiber VGCF, carbon nanotubes CNTs, and graphene, or composite conductive agents thereof.

[0123] In one embodiment of the present application, a method for preparing a negative electrode sheet is further provided, comprising the following step S10.

[0124] Step S10: forming a negative electrode active layer on at least one side of the current collector using a negative electrode active slurry; the negative electrode active slurry includes a negative electrode active material and a binding material.

[0125] The bonding material meets at least one of the following conditions:

[0126] (1) The bonding material includes the bonding composition of the first aspect.

[0127] (2) The bonding material includes a cross-linked polymer formed by a chemical reaction between the functional polymer in the bonding composition of the first aspect and the small molecule tertiary amine compound, and the reaction sites of the chemical reaction include the functional groups in the functional polymer and the functional groups in the small molecule tertiary amine compound.

[0128] It should be noted that when the binding material satisfies (2), the binding material can be prepared by chemically reacting the binding composition before mixing with the negative electrode active material, or by directly mixing the binding composition with the negative electrode active material into a negative electrode active slurry, coating it on the current collector, and then chemically reacting while drying to form the binding material.

[0129] Furthermore, the conditions of the chemical reaction may depend on the type of functional groups and functional groups. Different types will result in different chemical reactions, including but not limited to at least one of esterification reaction, dehydration condensation reaction of hydroxyl groups and hydroxyl groups, and acylation reaction of carboxyl groups and primary amino groups. In this case, the reaction conditions may be the commonly used reaction conditions in the art for esterification reaction, dehydration condensation reaction of hydroxyl groups and hydroxyl groups, and acylation reaction of carboxyl groups and primary amino groups.

[0130] In some embodiments, the negative electrode active slurry includes a solvent; further, the negative electrode active slurry has a solid content of 40 wt % to 80 wt %, and a viscosity at 25° C. adjusted to 5000 mPa·s to 25000 mPa·s.

[0131] In some embodiments, the solvent includes, but is not limited to, at least one of water, N-methylpyrrolidone, and dimethylformamide.

[0132] In some embodiments, the steps of forming the negative electrode active layer in step S10 are specifically as follows:

[0133] The negative electrode active slurry is coated on a current collector and dried to form a negative electrode active layer.

[0134] In some embodiments, the negative electrode active slurry further includes a conductive agent. Further, the type and amount of the conductive agent are the same as described above and will not be repeated here.

[0135] In one embodiment of the present application, a battery is further provided, comprising the above-mentioned negative electrode sheet or the negative electrode sheet prepared by the above-mentioned method for preparing the negative electrode sheet.

[0136] In some embodiments, the negative electrode active layer further comprises a functional interface film, the functional interface film comprising C3N - and CNO - At least one of .

[0137] The tertiary amine structure introduced into the bonding material can induce and participate in the formation of the functional film layer (SEI film) during the charge and discharge process, generating a special nitrogen-containing component: C3N - and CNO - , in order to optimize the composition of the functional film layer, and the nitrogen atom has a lone pair of electrons, which can accelerate the Li + The diffusion and transport of active ions further improve the cycle stability of the battery.

[0138] It should be noted that: C3N - and CNO - It represents the overall composition of the substance and the overall valence it presents.

[0139] In some embodiments, at least a portion of the surface of at least a portion of the active material is supported by a functional interface film.

[0140] In some embodiments, the functional interface film is subjected to TOF-SIMS testing to obtain a normalized secondary ion mass spectrum. In the secondary ion mass spectrum, C3N - The relative intensity ratio range R1 of the corresponding characteristic peak is: 0<R1≤0.3%.

[0141] In the above “0<R1≤0.3%”, the specific value of R1 includes the minimum value and the maximum value of the range, and every value between the minimum value and the maximum value. Specific examples include but are not limited to the point values ​​in the embodiments and the following point values: 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%; or a range consisting of any two values.

[0142] In some embodiments, the functional interface film is subjected to TOF-SIMS testing to obtain a normalized secondary ion mass spectrum. In the secondary ion mass spectrum, CNO - The relative intensity ratio range R2 of the corresponding characteristic peak is: 0.3%≤R2≤2%.

[0143] In the above “0.3%≤R2≤2%”, the specific value of R2 includes the minimum and maximum values ​​of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and the following point values: 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%; or a range consisting of any two values.

[0144] It can be understood that the time-of-flight secondary ion mass spectrometer TOF-SIMS analyzes the sample surface by sputtering an ion beam. The composition information and relative thickness of the interface film on the negative electrode surface can be obtained through TOF-SIMS. Specifically: TOF-SIMS excites the sample surface with primary ions to excite a trace amount of secondary ions, and measures the ion mass based on the different flight times of the secondary ions to the detector due to different masses, and analyzes the characteristic peaks corresponding to different substances. After normalization, the relative intensity ratio of each characteristic peak refers to the normalized statistics based on the total intensity of all detected characteristic peak ions as 100%, and calculates the relative intensity ratio percentage of the intensity corresponding to each characteristic peak. This value can indicate the relative mass ratio of the ions corresponding to each characteristic peak in the sample. The higher the relative intensity ratio percentage of the characteristic peak, the higher the mass ratio of the ions corresponding to the characteristic peak in the sample.

[0145] In some embodiments, the thickness H of the functional interface film is: 0<H≤60nm.

[0146] In the above “0<H≤60nm”, the specific value of H includes the minimum value and the maximum value of the range, and every value between the minimum value and the maximum value. Specific examples include but are not limited to the point values ​​in the embodiments and the following point values: 60nm, 55nm, 50nm, 45nm, 40nm, 35nm, 30nm, 25nm, 20nm, 15nm, 10nm, 9nm, 8nm, 7nm, 6nm, 5nm, 4nm, 3nm, 2nm, 1nm, 0.5nm, 0.1nm; or a range consisting of any two values.

[0147] It should be noted that the functional interface film is formed during the charge and discharge process of the battery. The charge and discharge process can be any charge and discharge process involved in the battery preparation and use steps, such as the conventional formation step or the detection step, or the charge and discharge process involved in actual recycling. The formation of the functional interface film is a dynamic development process. At each stage of the battery, the component content or thickness of the functional interface film changes dynamically.

[0148] Furthermore, when the above battery is manufactured and shipped, in the secondary ion mass spectrometry of the functional interface membrane, C3N - The relative intensity ratio range of the corresponding characteristic peak R1 is: 0<R1≤0.2%; CNO - The relative intensity ratio range of the corresponding characteristic peak R2 is: 0.3% ≤ R2 ≤ 1%; the thickness H of the functional interface film is: 0 < H ≤ 30nm; after the above battery is cycled for 20 times, in the secondary ion mass spectrum of the functional interface film, C3N - The relative intensity ratio range of the corresponding characteristic peak R1 is: 0<R1≤0.3%; CNO - The relative intensity ratio range R2 of the corresponding characteristic peak is: 0.3%≤R2≤1.5%; the thickness H of the functional interface film is: 0<H≤40nm.

[0149] In some embodiments, the functional interface film further comprises at least one of LiF, CHO2, Li2CO3, Li2O, and ROCO2Li.

[0150] In some embodiments, in the secondary ion mass spectrum of the functional interface film, the relative intensity ratios of the characteristic peaks corresponding to LiF, CHO2, Li2CO3, Li2O, and ROCO2Li are in the range of 0.2% to 2.0%, 0.1% to 2.0%, 0.1% to 2.0%, 0.001% to 0.5%, and 0.001% to 0.5%, respectively.

[0151] In some embodiments, the battery further includes a positive electrode sheet and a separator disposed between the positive electrode sheet and the negative electrode sheet.

[0152] The positive electrode sheet and the separator can be the positive electrode sheet and the separator applicable to various types of batteries in the art. Here, the separator and the positive electrode sheet are introduced non-restrictively, but are not limited to the following systems.

[0153] Positive electrode sheet: includes a current collector and a positive electrode active layer provided on at least one surface of the current collector, and the positive electrode active layer includes a positive electrode active material.

[0154] The positive electrode active material may be any positive electrode active material commonly used in the art, including but not limited to: positive electrode active materials for lithium ion batteries, positive electrode active materials for sodium ion batteries, and positive electrode active materials for potassium ion batteries.

[0155] The positive electrode active material of a lithium ion battery, the positive electrode active material of a sodium ion battery and the positive electrode active material of a potassium ion battery are hereinafter referred to as lithium ion active material, sodium ion active material or potassium ion active material, respectively.

[0156] Further, as an example, the lithium ion active material may include at least one of the following materials: lithium phosphates containing olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries can also be used. These positive electrode active materials can be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to: lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) or its modified compounds. Examples of lithium phosphates containing olivine structures may include but are not limited to at least one of lithium iron phosphate (such as LiFePO4, referred to as LFP), lithium manganese phosphate (such as LiMnPO4) or lithium manganese iron phosphate. In any embodiment of the present application, the molecular formula of the lithium ion active material is: LiFe x Mn (1-x) PO4, x is any number from 0 to 1.

[0157] It can be understood that when x is 0, LiFex Mn (1-x) PO4 is LiMnPO4 lithium manganese phosphate. When x is 1, LiFe x Mn (1-x) PO4 is LiFePO4 lithium iron phosphate (LFP).

[0158] It should be noted that the lithium content in the positive electrode material exemplified above refers to its content when it is not in use. During the use of the battery, it will be repeatedly used as a battery, and the Li in the positive electrode active material will change during the charge and discharge process. That is, the molar subscript of Li in the positive electrode active material in the battery product will not always remain at 1, but will change; further, the range of change can be (0 to 1.2).

[0159] For example, LiFe x Mn (1-x) PO4 can be further expressed as Li y Fe x Mn (1-x) PO4, y is 0~1.1.

[0160] For example, for the ternary material Li y (Ni a Co b Mn c ) 1-d M d O 2-x A x , y is 0.2~1.2, a+b+c=1, 0≤d≤1, 0≤x<2; M is one or more of Zr, Sr, B, Ti, Mg, Sn or Al, and A is one or more of S, N, F, Cl, Br or I.

[0161] The battery is accompanied by Li intercalation and deintercalation and consumption during the charge and discharge process. The molar content of Li varies when the battery is discharged to different states. The above definition of y includes the molar content of Li under different charge and discharge states of the battery. Furthermore, the battery voltage is usually between 2-5V.

[0162] In some embodiments, the above-mentioned active material includes a high-voltage positive electrode active material; further, the above-mentioned active material includes a nickel-containing active material; for example, it can be at least one of a nickel-containing ternary material, lithium nickel cobalt oxide, lithium nickel manganese oxide or lithium nickel cobalt manganese oxide; more specifically, it can be at least one of lithium nickel manganese cobalt oxide, nickel manganese spinel or nickel-rich lithium manganese oxide.

[0163] As an example, the sodium ion active material may include at least one of the following materials: a sodium transition metal oxide, a polyanionic compound, or a Prussian blue compound. However, the present application is not limited to these materials, and other conventionally known materials that can be used as sodium ion battery positive electrode active materials may also be used.

[0164] As an optional technical solution of the present application, in the sodium transition metal oxide, the transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr or Ce. Sodium transition metal oxide is, for example, Na x MO2, wherein M includes at least one or more of Ti, V, Mn, Co, Ni, Fe, Cr or Cu, and 0<x≤1.

[0165] As an optional technical solution of the present application, the polyanionic compound can be a compound having sodium ions, transition metal ions and tetrahedral (YO4) n- A class of compounds with anionic units. The transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr or Ce; Y includes at least one of P, S or Si; n represents (YO4) n- valence.

[0166] Polyanionic compounds can also be sodium ions, transition metal ions, tetrahedral (YO4) n- A class of compounds containing anion units and halogen anions. The transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, or Ce; Y includes at least one of P, S, or Si, and n represents (YO4) n- valence state; the halogen may be at least one of F, Cl or Br.

[0167] Polyanionic compounds can also be sodium ions, tetrahedral (YO4) n- Anion unit, polyhedron unit (ZO y ) m+ and a class of compounds containing an optional halogen anion. Y includes at least one of P, S or Si, and n represents (YO4) n- valence state; Z represents a transition metal, including at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr or Ce, m represents (ZO y ) m+ valence state; the halogen may be at least one of F, Cl or Br.

[0168] Polyanionic compounds include NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7)(NFPP), NaM1PO4F or Na3(VO y )2(PO4)2F (3-2y) At least one of .

[0169] M1 is at least one of V, Fe, Mn or Ni, and 0≤y≤1.

[0170] Prussian blue compounds can be sodium ions, transition metal ions and cyanide ions (CN - ). The transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr or Ce. Prussian blue compounds are, for example, Na a M2 b M3 c (CN)6, wherein M2 and M3 are each independently selected from at least one of Ni, Cu, Fe, Mn, Co or Zn, 0<a≤2, 0<b<1, 0<c<1.

[0171] In any embodiment of the present application, the current collector may be a metal foil or a composite current collector. For example, as the metal foil, the negative electrode sheet may be copper foil, and the positive electrode sheet may be aluminum foil.

[0172] The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material on a polymer substrate.

[0173] In some embodiments, the metal material is selected from any one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver or silver alloy.

[0174] In some embodiments, the polymer material substrate includes at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE).

[0175] It can be understood that the current collector has two surfaces arranged opposite to each other in its own thickness direction, and the positive electrode active layer is sequentially provided on at least one surface, which can be one of the surfaces or both surfaces at the same time.

[0176] Diaphragm: The diaphragm is placed between the positive electrode and the negative electrode.

[0177] The type of the diaphragm of the present application can be any known porous structure diaphragm with good chemical stability and mechanical stability.

[0178] In some embodiments, the separator can be made of at least one of fiberglass, non-woven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer can be the same or different.

[0179] The thickness of the diaphragm is controlled to be 2 μm to 15 μm; optionally, the thickness of the diaphragm is controlled to be 2 μm to 13 μm.

[0180] In some embodiments, the battery further includes an electrolyte. Examples of the electrolyte are described below, including but not limited to the following.

[0181] Generally, the electrolyte solution includes an electrolyte salt and a solvent.

[0182] In some embodiments, the electrolyte salt may be selected from electrolyte salts commonly used in the art, such as lithium ion electrolyte salts.

[0183] As an example, the lithium ion electrolyte salt includes, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalatophosphate) (LiDFOP) or lithium tetrafluorooxalatophosphate (LiTFOP).

[0184] In some embodiments, the solvent can be selected from one or more of fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) or diethyl sulfone (ESE).

[0185] In some embodiments, the concentration of the electrolyte salt in the electrolyte solution is generally 0.5 mol / L to 15 mol / L.

[0186] The present application has no particular restrictions on the shape of the battery. The shape of the battery of the present application can be cylindrical, square or any other shape. For example, Figure 2 The battery cell 4 is a battery having a square structure as an example.

[0187] In some embodiments, reference Figure 3 The housing may include a shell 41 and a cover plate 43. The shell 41 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates together form a receiving cavity. The shell 41 has an opening communicating with the receiving cavity, and the cover plate 43 may be disposed over the opening to seal the receiving cavity.

[0188] The positive electrode sheet, separator and negative electrode sheet can be wound or laminated to form an electrode assembly 42, which is encapsulated in the receiving cavity. The number of electrode assemblies 42 included in the battery cell 4 can be one or more, which can be adjusted according to needs.

[0189] The battery includes one or more battery cells 4 .

[0190] The battery may be a battery module or a battery pack; the battery module or battery pack includes at least one battery cell 4. The number of battery cells contained in the battery module may be one or more, and those skilled in the art may select an appropriate number based on the application and capacity of the battery module.

[0191] Figure 4 and Figure 5 The battery pack 1 is shown as an example. The battery pack 1 includes a battery case and one or more battery cells 4 disposed within the battery case. The battery case includes an upper case 2 and a lower case 3. The upper case 2 can be placed over the lower case 3 to form an enclosed space for the battery cells 4.

[0192] The plurality of battery cells 4 can be arranged in the battery box in any manner.

[0193] The present application also provides an electrical device, which includes the above-mentioned battery.

[0194] Furthermore, in the above-mentioned electrical device, the battery may exist in the form of a battery cell, or may be further assembled into a battery pack.

[0195] The above-mentioned battery or the battery pack assembled therefrom can be used as a power source for an electrical device, or as an energy storage unit for an electrical device.

[0196] The above-mentioned electrical devices may be, but are not limited to, mobile devices, electric vehicles, electric trains, ships, satellites, energy storage systems, etc.

[0197] In some embodiments, the mobile device may be a mobile phone or a laptop computer, etc.

[0198] In some embodiments, electric vehicles include, but are not limited to, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, and the like.

[0199] Figure 6 The power consumption device 5 is taken as an example. The power consumption device 5 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the power consumption device 5's requirements for high power and high energy density of the battery, a battery pack can be used.

[0200] As another example, the power-consuming device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be light and thin, and may use a battery as a power source.

[0201] The present application will be described below in conjunction with specific embodiments, but the present application is not limited to the following embodiments. It should be understood that the attached claims summarize the scope of the present application. Under the guidance of the concept of the present application, those skilled in the art should realize that certain changes made to the various embodiments of the present application will be covered by the spirit and scope of the claims of the present application.

[0202] The following are specific examples.

[0203] Example 1

[0204] S1: 771 mg of polyacrylic acid slurry (35 wt%, solvent is water, weight average molecular weight is 25w) is dispersed in 9.2 g of deionized water, and then 30 mg of nitrilotriacetic acid is added and dissolved in the solution, and mixed to obtain a mixed solution of the bonding composition with a concentration of 3%.

[0205] Concentration of the mixed solution of the bonding composition = total mass of the bonding composition (functional polymer + small molecule tertiary amine compound) / total mass of the mixed solution of the bonding composition × 100%.

[0206] The mass ratio of the functional polymer (polyacrylic acid contained in the polyacrylic acid slurry) to the small molecular tertiary amine compound (nitrilotriacetic acid) in the mixed solution of the bonding composition is denoted as X1. Please see Table 1 for specific values.

[0207] S2: Place nano-silicon particles, conductive carbon black, single-walled carbon nanotubes (SWCNTs) and a mixed solvent of the above-mentioned bonding composition in water and mix to obtain a negative electrode active slurry, wherein the mass ratio of the bonding composition (functional polymer + small molecule tertiary amine compound) in the mixed solvent of nano-silicon particles, conductive carbon black, single-walled carbon nanotubes (SWCNTs) and the above-mentioned bonding composition is 70:9:1:20.

[0208] S3: The above-mentioned negative electrode active slurry was coated on the surface of the current collector (copper foil, thickness of 6 μm), dried at 80°C to remove the solvent, and a negative electrode active layer was formed to obtain a negative electrode sheet. The coating surface density was 1.8 mg / cm 2 .

[0209] It should be noted that, in the process of preparing the negative electrode active slurry, the solvent in the negative electrode active slurry is evaporated, and the mass proportion Y1 of the binding material in the negative electrode active layer is: the mass of the binding composition in the negative electrode active slurry to the total mass of the components in the negative electrode active slurry excluding the solvent. Please see Table 1 for specific values.

[0210] The negative electrode active layer components on the prepared negative electrode sheet were sampled and dispersed in ethanol and observed under a transmission electron microscope (TEM). The electron microscope image is as follows: Figure 7 As shown, it can be clearly observed that the surface of the silicon particles is supported by a film composed of a continuous phase.

[0211] Furthermore, the negative electrode active layer of the negative electrode sheet, the raw material polyacrylic acid slurry and the raw material nitrilotriacetic acid were sampled and tested by Fourier transform infrared spectrometer, and the main characteristic peaks of each were obtained. The main characteristic peak of the FTIR of the raw material polyacrylic acid slurry was 3225cm -1 (-OH) and 1700cm -1 (C=O); The main characteristic peak of FTIR of raw material nitrilotriacetic acid: 3040cm -1 and 1710cm -1 (for the carboxyl part); the main characteristic peak of the negative electrode active layer FTIR: 3155cm -1 (-OH) and 1690cm -1 (C=O).

[0212] The bonding strength of the prepared negative electrode sheets was tested. The specific steps were as follows: a 20mm wide and 160mm long negative electrode sheet sample was cut and attached to a steel plate with double-sided tape. A paper sheet the same width as the electrode sheet was then secured with tape. A 180° peel test was then performed to obtain the bonding strength data. The results are shown in Table 1.

[0213] S4: Preparation of batteries

[0214] The negative electrode sheet prepared above was cut into Φ=12mm discs and assembled in the order of outer shell, spring sheet, gasket, lithium sheet (counter electrode), diaphragm, the negative electrode sheet, and outer shell in an argon-filled glove box (H2O<0.1ppm, O2<0.1ppm). The electrolyte was injected and then packaged to obtain a button battery.

[0215] Among them, the electrolyte of the electrolyte is LiPF6, the concentration of the electrolyte in the solvent is 1 mol / L, the solvent is a mixture of diethyl carbonate (DEC) and ethylene carbonate (EC) with a mass ratio of 1:1, and 10wt% of the additive fluoroethylene carbonate (FEC) is added.

[0216] S5: Testing

[0217] (1) Cyclic performance test

[0218] Take the above battery and perform a constant current charge and discharge test on the battery at room temperature of 25°C using a Neware battery tester CT-3008-S4: charge and discharge cycles at 0.2 A / g for 2 cycles, then charge and discharge cycles at 0.4 A / g for 2 cycles, and then charge and discharge cycles at 0.8 A / g for 1 cycle. The capacity at this time is recorded as C5. Continue to cycle charge and discharge at 0.8 A / g. The capacity of the battery after a total of n cycles (including the aforementioned 5 cycles) is recorded as Cn. The capacity retention rate of the battery after n cycles is recorded as Pn, Pn = Cn / C5×100%.

[0219] The capacity retention rate after 100 cycles is recorded as P100. Please see Table 1 for details.

[0220] Furthermore, the negative electrode sheet in the battery that has been cycled 100 times was disassembled, the cracking condition on the surface of the negative electrode sheet was observed, and the thickness change rate W of the negative electrode sheet was calculated.

[0221] W = thickness of negative electrode sheet after 100 cycles / original thickness of negative electrode sheet

[0222] Please see Table 1 for specific test results.

[0223] (2) Characterization test of functional interface film:

[0224] According to the steps of the cycle performance test (1) above, the cycle performance test was performed for 20 cycles and 100 cycles respectively, and then the battery was disassembled. The functional interface film on the surface of the negative electrode active layer after cyclic charge and discharge was tested by TOF-SIMS according to the following steps to obtain a normalized secondary ion mass spectrum. The components of the functional interface film and the intensity of its characteristic peaks, as well as the thickness of the functional interface film, were analyzed based on the secondary ion mass spectrum information:

[0225] (1) The battery after the above-mentioned cyclic charge and discharge is disassembled to separate the negative electrode sheet, and the functional interface film (SEI) on the surface of the negative electrode active layer after the cycle is etched using TOF-SIMS to obtain a normalized secondary ion mass spectrum. Based on the secondary ion mass spectrum information, the component types of the functional interface film, the intensity of its characteristic peaks, and the thickness of the functional interface film are analyzed.

[0226] The specific components and their mass ratios are shown in Table 2.

[0227] Furthermore, the functional interface film on the surface of the negative electrode active layer after 20 cycles was subjected to elemental analysis using an X-ray photoelectron spectrometer, and the elements and their contents were: C: 56.40%, O: 34.90%, F: 7.1%, P: 0.90%, and N: 0.7%.

[0228] Examples 2 to 4

[0229] Examples 2 to 4 are substantially the same as Example 1, except that the amounts of polyacrylic acid slurry and nitrilotriacetic acid in step S1 are different from those in Example 1, so that the value of X1 is different from that in Example 1. For specific values, see Table 1.

[0230] The other steps are the same as those in Example 1. Please see Table 1 for specific parameters and results.

[0231] Examples 5-6

[0232] Examples 5 to 6 are substantially the same as Example 1, except that in step S1 , nitrilotriacetic acid is replaced by ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid of equal mass, respectively.

[0233] The other steps are the same as those in Example 1. Please see Table 1 for specific parameters and results.

[0234] Example 7

[0235] Example 7 is basically the same as Example 1, except that steps S1 to S3 are as follows:

[0236] S1: 0.27 g of polyvinyl alcohol (weight average molecular weight of 25w) powder was dissolved in 9.7 g of water to obtain a polyvinyl alcohol solution, and then 30 mg of nitrilotriacetic acid was added and dissolved in the polyvinyl alcohol solution, and mixed to obtain a mixed solution of a bonding composition with a concentration of 3%.

[0237] Concentration of the mixed solution of the bonding composition = total mass of the bonding composition (functional polymer + small molecule tertiary amine compound) / total mass of the mixed solution of the bonding composition × 100%.

[0238] The mass ratio of the functional polymer (polyvinyl alcohol contained in the polyvinyl alcohol slurry) to the small molecular tertiary amine compound (nitrilotriacetic acid) in the mixed solution of the bonding composition is denoted as X1. Please see Table 1 for specific values.

[0239] The mixed solution of the bonding composition was heated at 90° C. for 5 hours to obtain a mixed solution containing a cross-linked bonding material.

[0240] S2: Place a mixed solution of nano-silicon particles, conductive carbon black, single-walled carbon nanotubes (SWCNTs) and the above-mentioned cross-linked binding material in water and mix them to obtain a negative electrode active slurry, wherein the mass ratio of the cross-linked binding material in the mixed solution of nano-silicon particles, conductive carbon black, single-walled carbon nanotubes (SWCNTs) and the above-mentioned cross-linked binding material is 70:9:1:20.

[0241] S3: Same as step S3 in Example 1.

[0242] At this time, Y1 is: the percentage of the mass of the cross-linking binder in the negative electrode active slurry to the total mass of the components in the negative electrode active slurry excluding the solvent. Please see Table 1 for specific values.

[0243] The other steps are the same as those in Example 1. Please see Table 1 for specific parameters and results.

[0244] Example 8

[0245] Example 8 is basically the same as Example 1, except that: in step S2, while ensuring that the total mass of the bonding composition in the mixed solvent of the conductive carbon black and the bonding composition is the same as that in Example 1, the feeding of the mixed solvent of the conductive carbon black and the bonding composition is further regulated to maintain the mass ratio of the negative electrode active material and the single-walled carbon nanotubes in the formed negative electrode active layer the same as that in Example 1, and the total mass ratio of the conductive carbon black and the above-mentioned bonding composition is the same as that in Example 1, while making the respective mass ratios of the conductive carbon black and the above-mentioned bonding composition in the negative electrode active layer different from that in Example 1, that is, the Y1 value is different. Please see Table 1 for details.

[0246] The other steps are the same as those in Example 1. Please see Table 1 for specific parameters and results.

[0247] Example 9

[0248] Example 9 is essentially the same as Example 1, differing only in that in step S2, the nano-silicon particles are replaced with graphite. The mass ratio of graphite, conductive carbon black, single-walled carbon nanotubes (SWCNTs), and the bonding composition (functional polymer + small molecule tertiary amine compound) in the mixed solvent of the bonding composition is 95:1.5:0.5:3.

[0249] The cycle performance test steps in step S5 are as follows:

[0250] Take the above battery and perform constant current charge and discharge test on the battery at room temperature of 25℃ using Neware battery tester CT-3008-S4: activate 2 cycles of charge and discharge at 0.1C constant current between 0.005V and 2V, then cycle 2 cycles of charge and discharge at 0.5C constant current, and then cycle 1 cycle of charge and discharge at 1C. The capacity at this time is recorded as C5. Continue to cycle charge and discharge at 1C constant current. The capacity of the battery after a total of n cycles (including the aforementioned 5 cycles) is recorded as Cn. The capacity retention rate of the battery after n cycles is recorded as Pn, Pn = Cn / C5×100%.

[0251] The other steps are the same as those in Example 1. Please see Table 1 for specific parameters and results.

[0252] Comparative Example 1

[0253] Comparative Example 1 is substantially the same as Example 1, except that in step S2, the bonding composition is directly replaced with polyacrylic acid slurry, and the mass of the polyacrylic acid in the polyacrylic acid slurry is the same as that of the bonding composition in Example 1.

[0254] The other steps are the same as those in Example 1. Please see Tables 1 and 2 for specific parameters and results.

[0255] Among them, the functional interface film on the surface of the negative electrode active layer of the battery prepared in comparison 1 after 20 cycles was subjected to elemental analysis testing using an X-ray photoelectron spectrometer, and the elements and their contents were: C: 45.01%, O: 49.68%, F: 4.61%, P: 0.70%, N: null (not detected).

[0256] Comparative Example 2

[0257] Comparative Example 2 is basically the same as Example 9, except that in step S2, the bonding composition is directly replaced with CMC-SBR (CMC: SBR mass ratio = 2:3, both purchased from Shenzhen Kejing), and the mass of CMC-SBR is the same as that of the bonding composition in Example 1.

[0258] The other steps are the same as those in Example 1. Please see Tables 1 and 2 for specific parameters and results.

[0259] Comparative Example 3

[0260] Comparative Example 3 is substantially the same as Example 1, except that steps S1 to S3 are as follows:

[0261] S1: 0.27 g of polyvinyl alcohol was dissolved in 9.7 g of water to obtain a polyvinyl alcohol solution, and then 30 mg of triacrylic acid was added and dissolved in the solution, followed by mixing to obtain a mixed solution of a bonding composition with a concentration of 3%.

[0262] Concentration of the mixed solution of the adhesive composition = total mass of the adhesive composition (functional polymer + triacrylic acid) / total mass of the mixed solution of the adhesive composition × 100%.

[0263] The mass ratio of the functional polymer to triacylglycerol in the mixed solution of the bonding composition is denoted as X1. Please see Table 1 for specific values.

[0264] The mixed solution of the bonding composition was heated at 90° C. for 5 hours to obtain a mixed solution containing a cross-linked bonding material.

[0265] S2: Place a mixed solution of nano-silicon particles, conductive carbon black, single-walled carbon nanotubes (SWCNTs) and the above-mentioned cross-linked binding material in water and mix them to obtain a negative electrode active slurry, wherein the mass ratio of the cross-linked binding material in the mixed solution of nano-silicon particles, conductive carbon black, single-walled carbon nanotubes (SWCNTs) and the above-mentioned cross-linked binding material is 70:9:1:20.

[0266] S3: Same as step S3 in Example 1.

[0267] At this time, Y1 is: the percentage of the mass of the cross-linking binder in the negative electrode active slurry to the total mass of the components in the negative electrode active slurry excluding the solvent. Please see Table 1 for specific values.

[0268] The other steps are the same as those in Example 1. Please see Tables 1 and 2 for specific parameters and results.

[0269] The relevant parameters and performance test results of each embodiment and comparative example are shown in Tables 1 and 2.

[0270] Table 1

[0271]

[0272]

[0273] In Table 1, “ / ” represents the absence of the substance or parameter.

[0274] The test results of the functional interface film of Example 1 and Comparative Examples 1 to 3 are shown in Table 2, wherein the functional interface film components of each stage of the battery of each embodiment and comparative example include: LiF, CHO2 - , Li2CO3, Li2O, rOCO2Li, and some of the different components are shown in Table 2.

[0275] Table 2

[0276]

[0277] In Table 2, “ / ” indicates that the test was conducted but the substance or structure could not be detected; the relative intensity ratio is the data recorded after multiple tests. The test results fluctuate each time, so the fluctuation range is recorded; “null” indicates that the test result was not obtained after the test was completed.

[0278] Analysis of the data in Table 1, comparing the data of Examples 1-8 with Comparative Examples 1 and 3, and comparing the data of Example 9 with Comparative Example 2, reveals that, on the one hand, the negative electrode sheet produced using the binding composition of the present application exhibits excellent binding properties, maintaining good binding capacity during the battery's charge-discharge cycle. On the other hand, combined with the components of the functional interface film formed on the negative electrode sheet in the battery in Table 2, and the elemental analysis of the functional interface films in Comparative Example 1 and Example 1, it is clear that the negative electrode sheet produced using the binding composition of the present application can form specific nitrogen-containing substances. Thus, the negative electrode sheet produced using the binding composition of the present application can improve the battery's cycling stability.

[0279] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0280] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make several modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the appended claims, and the specification and drawings may be used to interpret the claims.

Claims

1. A bonding composition, characterized in that include: Functional polymers containing functional groups and small molecule tertiary amine compounds containing functional groups, wherein the functionality of the functional groups in the small molecule tertiary amine compounds is ≥2; The functional group in the functional polymer and the functional group in the small molecule tertiary amine compound meet at least one of the following conditions: (1) The functional group and the functional group can form a hydrogen bond; (2) The functional group and the functional group can undergo chemical reaction.

2. The bonding composition according to claim 1, wherein The mass ratio of the functional polymer to the small molecule tertiary amine compound is (1-19):

1.

3. The bonding composition according to claim 1, wherein The mass ratio of the functional polymer to the small molecule tertiary amine compound is (7-10):

1.

4. The bonding composition according to any one of claims 1 to 3, characterized in that The functional group and the functional group are independently selected from at least one of a hydroxyl group, a carboxyl group, an amide group and a primary amine group.

5. The bonding composition according to any one of claims 1 to 4, characterized in that The small molecule tertiary amine compound is shown in formula (A): Among them, each R a are independently selected from an alkyl group having 1 to 5 carbon atoms, an aromatic group having 6 to 10 ring atoms, a heteroaromatic group having 5 to 10 ring atoms, a group substituted by the functional group or -N(R b )2 substituted alkyl with 1 to 5 carbon atoms, heteroaromatic group with 5 to 10 ring atoms substituted by the functional group, aromatic group with 6 to 10 ring atoms substituted by the functional group, cyano group, halogen, and at least two R a Selected from the functional group or -N(R b )2 substituted alkyl group having 1 to 5 carbon atoms, heteroaromatic group having 5 to 10 ring atoms substituted by the functional group, or aromatic group having 6 to 10 ring atoms substituted by the functional group; Each R b Each of them is independently selected from any one of an alkyl group having 1 to 5 carbon atoms substituted by the functional group, a heteroaromatic group having 5 to 10 ring atoms substituted by the functional group, and an aromatic group having 6 to 10 ring atoms substituted by the functional group.

6. The bonding composition according to any one of claims 1 to 4, characterized in that The small molecule tertiary amine compound includes at least one of nitrilotriacetic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid.

7. The bonding composition according to any one of claims 1 to 6, wherein The functional polymer satisfies at least one of the following conditions (1) to (2): (1) The functional polymer includes a polymer of formula (I): wherein R1 and R2 are independently selected from H, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a cyano group, a halogen group, a substituted or unsubstituted aromatic group having 6 to 10 ring atoms, a substituted or unsubstituted heteroaromatic group having 5 to 10 ring atoms, and any one of the functional groups, and at least one R1 or at least one R2 is selected from the functional groups, L is selected from a single bond or oxygen; n is the degree of polymerization; (2) The functional polymer is a water-soluble polymer.

8. The bonding composition according to any one of claims 1 to 7, wherein The functional polymer includes at least one of acrylic polymer, polyvinyl alcohol, polyethylene glycol and polyacrylamide.

9. A negative electrode sheet, characterized in that: The negative electrode sheet includes a current collector and a negative electrode active layer provided on at least one surface of the current collector. The negative electrode active layer includes a negative electrode active material and a binding material. The binding material satisfies at least one of the following conditions: (1) The bonding material comprises the bonding composition according to any one of claims 1 to 8; (2) The bonding material comprises a cross-linked polymer formed by a chemical reaction between the functional polymer in the bonding composition according to any one of claims 1 to 8 and the small molecule tertiary amine compound, and the reaction sites of the chemical reaction include the functional groups in the functional polymer and the functional groups in the small molecule tertiary amine compound.

10. The negative electrode sheet according to claim 9, wherein: In the negative electrode active layer, the mass proportion of the binding material is 1% to 20%.

11. The negative electrode sheet according to any one of claims 9 to 10, characterized in that: The negative electrode sheet satisfies at least one of the following conditions (1) to (3): (1) The negative electrode active material includes at least one of a silicon-based active material and a carbon-based active material; (2) In the negative electrode active layer, the mass proportion of the negative electrode active material is 60% to 99%; (3) The negative electrode active layer further includes a conductive agent, and the conductive agent accounts for 0.05% to 30% by mass in the negative electrode active layer.

12. A method for preparing a negative electrode sheet, characterized in that: The steps include: A negative electrode active slurry is used to form a negative electrode active layer on at least one side of the current collector; the negative electrode active slurry includes a negative electrode active material and a binding material, and the binding material meets at least one of the following conditions: (1) The bonding material comprises the bonding composition according to any one of claims 1 to 8; (2) The bonding material comprises a cross-linked polymer formed by a chemical reaction between the functional polymer in the bonding composition according to any one of claims 1 to 8 and the small molecule tertiary amine compound, and the reaction sites of the chemical reaction include the functional groups in the functional polymer and the functional groups in the small molecule tertiary amine compound.

13. A battery, characterized in that: The battery comprises the negative electrode sheet according to any one of claims 1 to 11 or the negative electrode sheet prepared by the method for preparing the negative electrode sheet according to claim 12.

14. The battery according to claim 13, wherein The negative electrode active layer also contains a functional interface film, the components of which include C3N - and CNO - At least one of .

15. The battery according to claim 14, wherein The functional interface film is subjected to a TOF-SIMS test to obtain a normalized secondary ion mass spectrum, wherein the secondary ion mass spectrum satisfies at least one of the following conditions (1) to (2): (1)C3N - The relative intensity ratio range of the corresponding characteristic peak R1 is: 0<R1≤0.3%; (2) CNO - The relative intensity ratio range R2 of the corresponding characteristic peak is: 0.3%≤R2≤2%.

16. The battery according to any one of claims 14 to 15, characterized in that The negative electrode sheet satisfies at least one of the following conditions (1) to (2): (1) The thickness H of the functional interface film is: 0<H≤60nm; (2) The functional interface film is supported on at least a portion of the surface of at least a portion of the negative electrode active material.

17. The battery according to any one of claims 14 to 16, characterized in that The functional interface film also includes LiF, CHO2 - , Li2CO3, Li2O, rOCO2Li, r is Li or an alkyl group.

18. An electrical device, characterized in that: The electrical device comprises the battery according to any one of claims 13 to 17.

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