CN116875227A

CN116875227A - Adhesive and preparation method thereof, electrode plate, secondary battery and power utilization device

Info

Publication number: CN116875227A
Application number: CN202311143999.0A
Authority: CN
Inventors: 吴凯; 郑仕兵; 靳超; 叶永煌; 钟铭; 吴子睿
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-09-06
Filing date: 2023-09-06
Publication date: 2023-10-13
Anticipated expiration: 2043-09-06
Also published as: CN116875227B

Abstract

The application relates to the technical field of secondary batteries, and provides an adhesive, a preparation method thereof, an electrode plate, a secondary battery and an electric device. The adhesive provided by the application comprises a compound with a chemical formula ofThe polymers shown. The book is provided withAccording to the application embodiment, through designing the molecular structure, the adhesive with the network crosslinking structure is provided, the adhesive can be uniformly coated on the particle surface of the electrode material, the electrode plate is endowed with higher adhesive force, transition metal ions in the electrode material can be chelated, the dissolution of the metal ions is inhibited, the structural stability of the cathode active material is improved, and the battery surface has higher cycle stability and lower direct current impedance.

Description

Adhesive and preparation method thereof, electrode plate, secondary battery and power utilization device

Technical Field

The application belongs to the technical field of secondary batteries, and particularly relates to an adhesive and a preparation method thereof, an electrode plate, a secondary battery and an electric device.

Background

Lithium Ion Batteries (LIBs) are of great interest because of their long life, high energy density, low maintenance costs, and the like. Currently, LIBs have been widely used in the fields of electric automobiles, portable electronic devices, energy storage systems, and the like.

The binder is a common material in lithium ion batteries and is widely applied to battery pole pieces, isolating films, packaging parts and the like. Existing binders generally comprise water-soluble binders and solvent-based binders, wherein the water-soluble binders can be dissociated into electrolyte in the electrochemical process, and the risk of pole piece demolding exists; the solvent type adhesive has high production cost, insufficient productivity and great harm to the environment. In addition, the existing adhesive is easy to gel in the preparation process, so that the slurry stability is poor, the prepared pole piece is low in adhesive force and yield, the direct current impedance of the battery is high, the circulating capacity retention rate is low, and the requirements of the market on the cost and performance of the battery are difficult to meet. Thus, the existing adhesives remain to be improved.

The statements made above merely serve to provide background information related to the present disclosure and may not necessarily constitute prior art.

Disclosure of Invention

The application aims to provide an adhesive and a preparation method thereof, an electrode plate, a secondary battery and an electric device, and aims to solve the technical problems of high direct current impedance growth rate and low cycle capacity retention rate of a lithium ion battery.

In order to achieve the purposes of the application, the technical scheme adopted by the application is as follows:

In a first aspect, embodiments of the present application provide a binder, the binder comprising a polymer having a chemical formula as shown in formula I:

i is a kind of

Wherein, the R comprises an electron donating group;

m is a natural number greater than or equal to 10, and n is a natural number greater than or equal to 10.

In the embodiment of the application, the bridging group R can be connected with a plurality of main chain polymers through amide bonds, and meanwhile, electron donating groups contained in the R groups can form hydrogen bonds between adjacent R groups, so that the binder molecules can form a network crosslinking structure taking the amide bonds as nodes and the hydrogen bonds as branched chains, thereby obviously improving the cohesive force of the binder. Meanwhile, the electron donating group contained in the R group enables the bridging group to have higher electronegativity, can chelate with transition metal, shields the structural phase change of the surface of the electrode material in a high-voltage state, thereby improving the structural stability of the electrode material, and is also beneficial to the conduction of lithium ions, thereby improving the transmission rate of lithium ions, and enabling the secondary battery to show lower direct current impedance growth rate and higher cycle capacity retention rate.

In some embodiments, the electron donating group comprises at least one of an imino group, an oxy ether, a carbonyl group, a thioether, a sulfoxide group, a sulfone group, a sulfonic acid group, and a sulfonate. The electronegative atoms containing lone pairs, such as O, N, S, contained in the electron donating groups can be chelated with transition metals, so that structural phase change of the surface of the electrode material in a high-voltage state is shielded, elution of transition metal Co, ni, mn and other ions is inhibited, the structural stability of the positive electrode active material is improved, and the secondary battery has higher cycle capacity retention rate.

In some embodiments, R comprises at least one of a C1-C20 alkyl group, a C1-C20 hydroxyalkyl group, and a non-conjugated structure. The R group contains alkyl or hydroxyalkyl with proper length, so that the binder has higher binder and flexibility, and is beneficial to reducing the direct current impedance growth rate of the battery.

In some embodiments, R comprises at least one of the groups represented by formulas II-XII:

、、

formula II and formula III

、、、

Formula IV formula V formula VI

、、、

Formula VII formula VIII formula IX

、、，

Formula X formula XI formula XII.

The wavy line in the formulae II to XII represents the bonding position of R and the main chain polymer, specifically, represents the bonding position of R and the amide bond in the formula I, and in the formula IX, b is a natural number not less than 5.

In the embodiment of the application, the R groups shown in the formulas II-XII are bridged on the main chain polymer, so that the binder can form a network structure taking an amide bond as a node, the binder shows better cohesiveness, the prepared positive pole piece has higher shearing force, and the negative pole piece has higher binder; in addition, the oxygen ether, thioether, imino, sulfonyl and the like contained in the R group can chelate transition metals (nickel, manganese, cobalt and the like) in the electrode material, inhibit metal ions from dissolving out and slow down the increase rate of direct current impedance.

In some embodiments, R comprises a conjugated structure, and R comprising the conjugated structure has the formula-A ₁ -A-A ₂ -wherein a comprises at least one of imino, oxy-ether, carbonyl, thioether, sulfoxide, sulfone, sulfonic acid, sulfonate; a is that ₁ And A ₂ Independently selected from C ₆ ~C ₁₅ At least one of the aryl groups of (a).

In the embodiment of the application, the aryl conjugated structure contained in the R group can improve the glass transition temperature and flexibility of the binder molecules, so that the pole piece is not brittle broken in the coating and drying process, and meanwhile, the electronegative atoms such as oxygen, sulfur, nitrogen and the like contained in the R group can chelate transition metal ions and inhibit metal ion dissolution, so that the structural stability of the electrode material is improved, and the secondary battery shows higher cycling stability and lower direct current impedance.

In some embodiments, a comprises at least one of an imino group, an oxyether, a thioether, a sulfone group. Imino, oxyether, thioether, sulfone groups can form intermolecular hydrogen bonds with higher strength, so that the adhesive shows better cohesiveness.

In some embodiments, R containing conjugated structure includes at least one of the groups represented by formulas XIII through XX:

、、

formula XIII formula XIV

、、

XV type XVI

、、

Formula XVII formula XVIII

、。

Formula XIX formula XX

The wavy line in the formulae XIII to XX represents the bonding position of R to the main chain polymer, and specifically represents the bonding position of R to the amide bond in the formula I.

In the embodiment of the application, the bridging group R shown in the formulas XIII-XX is connected with the main chain polymer through the amide bond, so that the adhesive can form a network structure taking the amide bond as a node, and the adhesive shows better adhesion.

In some embodiments, the molar ratio of amide bonds to electron donating groups in the binder is 0.8 to 2.5:1.

in some embodiments, the molar ratio of amide bonds to electron donating groups in the binder is 2:1.

in the molar ratio range of the amide bond and the electron donating group provided by the embodiment of the application, the adhesive can form a cross-linked network structure taking the amide bond as a node, so that the adhesive has higher cohesiveness.

In some embodiments, the number average molecular weight of the binder is 50W to 400W. The number average molecular weight of the binder is controlled within a proper range, the binder shows higher binding performance, the pole piece prepared by the method has excellent binding power and flexibility, and the battery has lower direct current impedance growth rate and higher cycle capacity retention rate.

In some embodiments, the binder is in the infrared spectrum at wavenumber 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 、3300 cm ^-1 ~3400 cm ^-1 、3500 cm ^-1 Has an infrared characteristic peak at the location of (a).

The adhesive of the embodiment of the application has the wave number of 1650 and 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 An infrared characteristic peak, thereby indicating the presence of an amide bond in the binder; at wave number of 3500 cm ^-1 The infrared characteristic peak shows that amino group exists in the adhesive and the wave number is 3300 cm ^-1 ~3400 cm ^-1 An infrared characteristic peak at the location, indicating the presence of hydrogen bonds in the binder.

In a second aspect, an embodiment of the present application provides a method for preparing an adhesive, including the steps of:

polyacrylic acid and bridging monomer R- (NH) ₂ ) _a And (3) carrying out polymerization reaction to obtain the adhesive of the embodiment of the application, wherein a is a natural number more than or equal to 2.

In the embodiment of the application, polyacrylic acid and terminal polyamino functional group monomer R- (NH) ₂ ) _a The polymerization reaction is carried out under the polymerization condition, the terminal amino group in the bridging monomer is used for reacting with the carboxyl group in the polyacrylic acid to form an amide bond, and the bridging monomer contains the terminal polyamino functional group, so that the polymer shown in the formula I can be formed.

In some embodiments, the bridging monomer comprises a non-conjugated structure and the bridging monomer comprising a non-conjugated structure comprises at least one of the compounds shown in formulas XXI-XXXI:

、、

XXI formula XXII

、、、

Formula XXIII formula XXIV formula XXV

、、、

Formula XXVI formula XXVII formula XXVIII

、、，

Formula XXIX formula XXX formula XXXI

In formula XXVIII, b is a natural number of 5 or more.

The bridging monomers provided by the embodiment of the application comprise at least 2 terminal amino groups, and can form an adhesive with an alternating network structure with polyacrylic acid under the polymerization condition, so that the adhesive shows higher adhesive force.

In some embodiments, the bridging monomers comprise conjugated structures, containing a co-entityThe chemical formula of the bridging monomer of the yoke structure is (NH) ₂ ) _x -A ₁ -A-A ₂ -(NH ₂ ) _y Wherein A comprises at least one of imino, oxyether, carbonyl, thioether, sulfoxide, sulfonyl, sulfonic acid and sulfonate; a is that ₁ And A ₂ Independently selected from C ₆ ~C ₁₅ At least one of aryl groups of (a); x is a natural number greater than or equal to 1, and y is a natural number greater than or equal to 1.

The bridging monomer provided by the embodiment of the application at least comprises 2 terminal amino groups, so that an amide bond can be formed with polyacrylic acid, and the conjugated aryl groups can improve the flexibility of the adhesive, so that the adhesive has higher cohesiveness and flexibility.

In some embodiments, a comprises at least one of an imino group, an oxyether, a thioether, a sulfone group.

In some embodiments, the bridging monomer containing a conjugated structure comprises at least one of the compounds represented by formulas XXXII-XXXIX:

、、

Formula XXXII formula XXXIII

、、

Formula XXXIV formula XXXV

、、

Formula XXXVI formula XXXVII

、，

Formula XXXVIII formula XXXIX.

The bridging monomer shown in XXXII-XXXIX in the embodiment of the application can form an amide bond with polyacrylic acid, and the bridging monomer contains a terminal polyamino functional group, so that the binder molecule has a network structure taking the amide bond as a node, and the binder has higher binding force.

In a third aspect, embodiments of the present application provide an electrode slurry comprising an electrode active material and a binder comprising a binder according to embodiments of the present application and/or a binder prepared by a method of preparing a binder according to embodiments of the present application.

The binder provided by the embodiment of the application can be effectively and uniformly coated on the particle surfaces of electrode materials in the electrode slurry processing process, so that the surface stress of the materials is relieved, meanwhile, electronegative atoms containing lone pair electrons such as oxygen, nitrogen, sulfur and the like in the binder can be chelated with transition metal ions, and dissolution of the transition metal is inhibited, so that the electrode materials have higher structural stability, and the battery has higher cycle capacity retention rate and lower direct current impedance growth rate.

In some embodiments, the binder is 0.5% -5% by mass based on the total mass of the components in the electrode slurry other than the solvent.

In some embodiments, the binder is 1% -2% by mass based on the total mass of the components in the electrode slurry other than the solvent.

In the content range of the binder provided by the embodiment of the application, the binder with an alternating-current network structure can be uniformly covered on the particle surfaces of the electrode materials, which is beneficial to improving the stability of the electrode materials and the binding force of the pole pieces, so that the prepared battery has higher cycle capacity retention rate and lower direct-current impedance growth rate.

In some embodiments, the electrode active material is a positive electrode active material or a negative electrode active material.

It can be understood that when the electrode active material is a positive electrode active material, the obtained electrode slurry is a positive electrode slurry, and the prepared electrode sheet is a positive electrode sheet.

Similarly, when the electrode active material is a negative electrode active material, the obtained electrode slurry is a negative electrode slurry, and the prepared electrode plate is a negative electrode plate.

In a fourth aspect, an embodiment of the present application provides an electrode sheet, where the electrode sheet includes a current collector and an active layer disposed on at least one side of the surface of the current collector, and a preparation raw material of the active layer includes the binder according to the embodiment of the present application; or the active layer is prepared by adopting the electrode slurry of the embodiment of the application.

The electrode plate provided by the embodiment of the application has higher binding force and flexibility due to the inclusion of the binder.

In some embodiments, the electrode sheet is a positive electrode sheet or a negative electrode sheet.

In some embodiments, the shear force per unit length of active layer and current collector in the positive electrode sheet is not less than 0.7 MPa.

In some embodiments, the shear force per unit length of the active layer and the current collector in the positive electrode sheet is 0.7 MPa to 1.0 MPa.

The positive pole piece provided by the embodiment of the application has higher shearing force.

In some embodiments, the active layer in the negative electrode tab has a bond to the current collector of not less than 7N/m per unit length.

In some embodiments, the adhesion of the negative electrode active layer to the current collector per unit length is 7N/m to 50N/m.

The negative electrode plate provided by the embodiment of the application has higher adhesive force.

In a fifth aspect, an embodiment of the present application provides a secondary battery, including the electrode tab of the embodiment of the present application.

The secondary battery provided by the embodiment of the application has good cycle stability, good multiplying power performance and low direct current impedance.

In a sixth aspect, an embodiment of the present application provides an electric device including the secondary battery according to the embodiment of the present application. The secondary battery is used for providing electric energy.

The power utilization device provided by the embodiment of the application has long standby or endurance time.

The foregoing description is only an overview of the present application, and is intended to be implemented in accordance with the teachings of the present application in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present application more readily apparent.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:

FIG. 1 is a schematic illustration of a vehicle according to some embodiments of the application;

fig. 2 is an exploded view of a battery according to some embodiments of the present application;

fig. 3 is a schematic structural diagram of a battery cell according to some embodiments of the present application.

Wherein, each reference sign in the figure:

1000. a vehicle;

100. battery 200, controller 300, motor;

10. the box body comprises a box body 11, an upper box body 12 and a lower box body;

20. Battery cell, 21, casing, 22, electrode assembly, 23, apron.

Detailed Description

Embodiments of the technical scheme of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present application, and thus are merely examples, and are not intended to limit the scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having" and any variations thereof in the description of the application and the claims and the description of the drawings above are intended to cover a non-exclusive inclusion.

In the description of embodiments of the present application, the technical terms "first," "second," and the like are used merely to distinguish between different objects and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, and indicates that three relationships may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

In the description of the embodiments of the present application, the term "plurality" means two or more (including two), and similarly, "plural sets" means two or more (including two), and "plural sheets" means two or more (including two).

In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the embodiments of the present application.

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like should be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; or may be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to specific circumstances.

In the present application, "at least one" means one or more, and "a plurality" means two or more. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.

It should be understood that, in various embodiments of the present application, the sequence number of each process described above does not mean that the execution sequence of some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

The weights of the relevant components mentioned in the description of the embodiments of the present application may refer not only to the specific contents of the components, but also to the proportional relationship between the weights of the components, so long as the contents of the relevant components in the description of the embodiments of the present application are scaled up or down within the scope of the disclosure of the embodiments of the present application. Specifically, the mass described in the description of the embodiment of the application may be a mass unit known in the chemical industry field such as [ mu ] g, mg, g, kg.

Currently, the performance of LIBs, including energy density and lifetime, has not fully met various requirements, especially in the field of electric vehicles. Thus, the main direction of development today is to produce LIBs with higher energy density, lower cost and higher reliability. Positive electrode materials are one of the important factors that have made breakthroughs in this field, such as various types of positive electrode materials (e.g., liCoO ₂ 、LiNi _m Co _n Mn _1-m-n O ₂ 、LiNi _m Co _n Al _1-m-n O ₂ 、Li ₂ Mn ₂ O ₄ And LiFePO ₄ Etc.) have been widely used in LIBs. Wherein the nickel-rich cathode material (LiNi _m Co _n M _1-m-n O ₂ X is more than or equal to 0.6, M=Mn, al) becomes a research hot spot in recent years due to the advantages of high reversible capacity, low cost and the like, and the nickel content is continuously increased, so that a very considerable initial discharge specific capacity is obtained. However, nickel-rich materials cause anisotropic expansion/contraction of the material due to phase transition from H2 to H3 at high voltage, resulting in unstable structure and high oxidation state Ni ⁴⁺ The high activity of the nickel-rich anode material is easy to catalyze the electrolyte to decompose and produce gas, HF corrosion can lead to dissolution of transition metal ions Ni, co and Mn, and induction of SEI growth leads to DCR growth, so that the nickel-rich anode material has the problem of unstable structure in the use process, thereby having adverse effect on the electrochemical performance and reliability of LIBs.

Thus, those skilled in the art have focused on adding substances inhibiting side reactions, such as binders, additives, etc., to the electrode slurry, and in the prior art, polyacrylic acid, which is a typical water-soluble binder, has a high association ability, and can be dissolved in water and N-methylpyrrolidone, and because of its rigidity, particularly, a large number of carboxyl functional groups contained in the polyacrylic acid side chains can be agglomerated together due to the mutual hydrogen bonding action, the active materials cannot be effectively bound during the circulation process, the circulation performance of the battery can be only relieved to some extent, and the battery is subjected to brittle risks in practical applications, and needs to be modified.

In order to alleviate the problem of unstable structure of the positive electrode material, a multifunctional composite binder can be designed. For example, epoxy, a benzofluoride functional group and a dopamine group are modified on polypropylene to construct a crosslinking composite adhesive, and the adhesive has a hydrogen bond structure formed by an ortho-position hydroxyl group and an amide bond, wherein the hydroxyl group can chelate transition metal ions, inhibit dissolution of transition metal, inhibit hydrofluoric acid corrosion and the like, but the monomer cost for introducing the groups by the method is relatively high, and the adhesive cannot replace the current polyvinylidene fluoride system. For example, PVDF-g-PAMPS copolymers are prepared by graft copolymerizing 2-acrylamido-2-methylpropanesulfonic Acid (AMPS) onto polyvinylidene fluoride (PVDF) by a free radical polymerization process, and PVDF-g-PAMPS/PMMA blends are prepared by blending amorphous polymethyl methacrylate (PMMA), however, the cost of the corresponding PAMPS and PMMA is relatively high. For example, the soluble ionic crosslinked polymer obtained through carboxyl amino ion interaction and hydrogen bonding can effectively reduce capacity attenuation generated by active material expansion in the circulation process and inhibit electrode crack generation, but the soluble binder can be dissociated into electrolyte in the electrochemical process, so that the pole piece is at a risk of demoulding.

Against the background of the above, in a first aspect of embodiments of the present application, there is provided a binder comprising a polymer having the general chemical formula I:

i is a kind of

Wherein R comprises an electron donating group;

In the embodiment of the application, the adhesive molecules have amide bonds and intermolecular hydrogen bonds, and in addition, the bridging group can be connected with a plurality of main chain polymers through the amide bonds, so that the adhesive molecules are in a network crosslinking structure, and the molecular formula of the adhesive molecules can be shown as the formula I-a:

The compounds of the formula I-a,

wherein the ellipses in formula I-a represent hydrogen bonds formed between adjacent R groups, and the wavy lines of R linkages in formula I represent the bonding locations of R to the backbone polymer.

In some embodiments, the electron donating group comprises at least one of an imino group, an oxy ether, a carbonyl group, a thioether, a sulfoxide group, a sulfone group, a sulfonic acid group, and a sulfonate. In electron-donating groups contained in the R group, O, N, S and other electronegative atoms containing lone pairs can be chelated with transition metal, so that structural phase change of the surface of the electrode material in a high-voltage state is shielded, elution of transition metal Co, ni, mn and other ions is inhibited, the structural stability of the electrode material is improved, lithium ion conduction is facilitated, the transmission rate of lithium ions is improved, and the secondary battery shows a lower direct current impedance growth rate and a higher cycle capacity retention rate.

In the technical scheme of the application, the existence of the amide bond and the existence of the oxyether, thioether, sulfonic group or sulfonate in the electron donating group lead the binder molecules to have higher water solubility and chain segment flexibility, thereby being beneficial to uniformly dispersing the binder in the electrode slurry, forming a uniform network coating structure on the surface of the active material particles, effectively binding the active material, effectively increasing the shearing force of the positive electrode plate and the binding force of the negative electrode plate, and simultaneously buffering the surface stress of the electrode material, thereby stabilizing the electrode interface, improving the stability of the battery, and further improving the electrochemical performance and reliability of LIBs.

The term "oxyether" refers to a group having an-O-group.

The term "thioether" refers to a group having a-S-group.

The term "carbonyl" refers to a group having-c=o-.

The term "imino" refers to a group having the group-NH-.

The term "sulfoxide" refers to a group having a-SO-group.

The term "sulfone group" means having the meaning of-SO ₂ -a group.

The term "sulfonic acid group" means having the group-SO ₃ H.

The term "sulfonate" refers to having the meaning-SO ₃ M (M comprises lithium or sodium).

In some embodiments, R comprises at least one of a C1-C20 alkyl group, a C1-C20 hydroxyalkyl group, and a non-conjugated structure.

The term "alkyl" refers to a saturated hydrocarbon containing primary (normal) carbon atoms, secondary carbon atoms, tertiary carbon atoms, quaternary carbon atoms, or combinations thereof. Phrases containing this term, e.g., "C ₁ ～C ₂₀ Alkyl "of (C) refers to alkyl groups containing from 1 to 20 carbon atoms, which at each occurrence may be, independently of one another, C ₁ Alkyl, C ₂ Alkyl, C ₃ Alkyl, C ₄ Alkyl, C ₅ Alkyl, C ₆ Alkyl, C ₇ Alkyl, C ₈ Alkyl, C ₉ Alkyl, C ₁₀ Alkyl, C ₁₁ Alkyl, C ₁₂ Alkyl, C ₁₃ Alkyl, C ₁₄ Alkyl, C ₁₅ Alkyl, C ₁₆ Alkyl, C ₁₇ Alkyl, C ₁₈ Alkyl, C ₁₉ Alkyl or C20 alkyl.

The term "hydroxyalkyl" refers to an alkyl group having an-OH group The terminal position of the group, i.e. the alkyl group as defined above, is attached with a hydroxyl group. Phrases containing this term, e.g., "C ₁ ～C ₂₀ Hydroxyalkyl "of (a) means that the alkyl moiety contains from 1 to 20 carbon atoms and, at each occurrence, can be independently of one another C ₁ Hydroxyalkyl, C ₄ Hydroxyalkyl, C ₅ Hydroxyalkyl, C ₈ Hydroxyalkyl, C ₁₀ Hydroxyalkyl, C ₁₂ Hydroxyalkyl, C ₁₅ Hydroxyalkyl or C ₂₀ Hydroxyalkyl groups.

The term "conjugated structure" refers to the presence in a molecule of a plurality of different double or triple bond structures linked by conjugation, sharing some conjugated pi electrons.

Similarly, the term "non-conjugated structure" refers to the absence of conjugated pi electrons in a molecule, i.e., the absence of multiple different double or triple bond structures in the molecule that are linked by conjugation.

The R group contains alkyl or hydroxyalkyl with proper length, so that the binder has higher binder and flexibility, can be uniformly covered on the particle surface of the electrode material, endows the electrode plate with higher binder or shearing force, can effectively buffer the surface stress of the electrode material, and further remarkably improves the structural stability of the electrode material, so that the secondary battery has lower direct current impedance growth rate and higher cycling stability.

、、

formula II and formula III

、、、

Formula IV formula V formula VI

、、、

Formula VII formula VIII formula IX

、、，

Formula X formula XI formula XII.

The wavy line in the formulas II to XII represents the bonding position of R and the main chain polymer, and specifically represents the bonding position of R and the amide bond in the formula I.

In formula IX, b is a natural number of 5 or more. In some embodiments, in formula IX, b is a natural number from 5 to 10.

The term "bonding site" refers to a site where the backbone polymer and bridging group are bound together by a chemical bond.

Illustratively, the presence of wavy lines in formula II indicates the position where R is bonded to the backbone polymer via an amide bond.

Illustratively, the plurality of wavy lines present in formula X each represent the position at which R is bonded to a different backbone polymer via an amide bond.

In the embodiment of the application, the R groups shown in the formulas II-XII at least comprise 2 sites for being combined with the main chain polymer, so that the R groups and the main chain polymer are connected into a network crosslinking structure through an amide bond, and because the R groups contain oxygen ether, thioether or imino groups and the like, intermolecular hydrogen bonds can be formed between the adjacent R groups, so that the adhesive shows better adhesion, the prepared positive electrode plate has higher shearing force, and the negative electrode plate has higher adhesive; in addition, oxygen atoms, nitrogen atoms, sulfur atoms and other electronegative atoms containing electrons in the R groups can chelate transition metals (nickel, manganese, cobalt and the like) in the electrode material, so that structural phase change of the electrode particles in a high-voltage state is shielded, metal ion dissolution is inhibited, and the secondary battery shows lower direct current impedance growth rate and higher cycle capacity retention rate.

The term "aryl" refers to an aromatic hydrocarbon radical derived from the removal of one hydrogen atom on the basis of an aromatic ring compound, which may be a monocyclic aryl radical, or a fused ring aryl radical, or a polycyclic aryl radical, at least one of which is an aromatic ring system for a polycyclic species. For example, "C ₆ ～C ₂₀ Aryl "of (a) refers to aryl groups containing from 6 to 20 carbon atoms, which at each occurrence may be, independently of one another, C ₆ Aryl, C ₁₀ Aryl or C ₂₀ Aryl groups. Suitable examples include, but are not limited to: benzene, biphenyl, naphthalene, anthracene, phenanthrene, perylene, triphenylene, and derivatives thereof. It will be appreciated that multiple aryl groups may also be interrupted by short non-aromatic units (e.g<10% of non-H atoms, such as C, N or O atoms), in particular acenaphthene, fluorene, or 9, 9-diaryl fluorene, triarylamine, diaryl ether systems, should also be included in the definition of aryl.

In the embodiment of the application, the aryl conjugated structure contained in the R group can improve the glass transition temperature and flexibility of the binder molecules, so that the pole piece is not brittle broken in the coating and drying process; the imino, oxyether, thioether, carbonyl and other groups contained in the R group can enable the binder to form intermolecular hydrogen bonds, so that the binder forms a network structure to be coated on the particle surface of the electrode material, the surface stress of the electrode material is relieved, the binding force of the pole piece is increased, and the structural stability of the electrode material is improved; meanwhile, electronegative atoms such as oxygen, sulfur, nitrogen and the like contained in the R group can chelate transition metal ions and inhibit metal ions from dissolving out, so that the structural stability of an electrode material is improved, and the secondary battery shows higher cycle stability and lower direct current impedance.

In some embodiments, a comprises at least one of an imino group, an oxyether, a thioether, a sulfone group. Imino, oxyether, thioether and sulfonyl groups enable the adhesive to form intermolecular hydrogen bonds with higher strength, so that the adhesive shows better cohesiveness.

、、

formula XIII formula XIV

、、

XV type XVI

、、

Formula XVII formula XVIII

、，

Formula XIX formula XX.

Illustratively, the presence of wavy lines in formula XIII indicates the position at which R is bonded to the backbone polymer via an amide bond.

Illustratively, the plurality of wavy lines present in formula XIV each represent the position at which R is bonded to a different backbone polymer via an amide bond.

In the embodiment of the application, the R group shown in the formulas XIII-XX at least comprises 2 sites for being combined with the main chain polymer, so that the R group and the main chain polymer are connected into a network crosslinking structure through an amide bond, and because the R group contains oxygen ether, thioether or imino groups and the like, intermolecular hydrogen bonds with higher strength can be formed between adjacent binder molecules, and the binder can show better cohesiveness; meanwhile, the electronegative atoms such as oxygen, sulfur, nitrogen and the like contained in the electrode material can chelate transition metal ions, inhibit the dissolution of the metal ions, and play an additive improving role in improving the structural stability of the electrode material; in addition, the aryl group contained in the R group represented by formulas XIII through XX can increase the segment flexibility of the binder. Therefore, the prepared secondary battery has higher cycle stability and lower direct current impedance growth rate.

In some embodiments, the molar ratio of amide bonds to electron donating groups in the binder is 0.8 to 2.5:1. in the range of the proportion of the amide bonds and the electron donating groups provided by the embodiment of the application, the number of the amide bonds in the binder is more, so that the binder has higher cohesiveness, and in addition, sufficient electronegative atoms containing lone pair electrons such as oxygen atoms, sulfur atoms and nitrogen atoms are also used for chelating transition metals in the electron donating groups, so that the electrode plate has higher cohesive force/shearing force and structural stability, and the secondary battery shows excellent electrochemical performance. In some embodiments, the molar ratio of amide bonds to electron donating groups can include, but is not limited to, 0.8:1, 1:1, 2:1, 2.5:1.

under the condition of the molar ratio of the amide bond and the electron donating group provided by the embodiment of the application, the binder can exert excellent cohesiveness and can effectively inhibit the structural phase change of the electrode material, so that the secondary battery has lower capacity loss and direct current impedance growth rate and higher cycle capacity retention rate.

In some embodiments, the number average molecular weight of the binder is 50W to 400W. The Number average molecular weight (Number-average Molecular Weight) means that the polymer is composed of a homogeneous mixture of identical chemical compositions and varying degrees of polymerization, i.e. of a mixture of polymers of different molecular chain lengths. The size of the molecules is usually characterized by an average number of molecules. The number average is referred to as the number average molecular weight, and is denoted by (MN). Number average molecular weight = sum of the molecular weights of the components mole number of the components per total mole number. According to the embodiment of the application, the number average molecular weight of the binder is controlled within a proper range, the binder shows higher binding performance, so that the prepared pole piece has excellent binding force and flexibility, and the battery has lower direct current impedance growth rate and higher cycle capacity retention rate. In some embodiments, the number average molecular weight of the binder may include, but is not limited to, 50W to 70W, or 70W to 100W, or 100W to 150W, or 150W to 200W, or 200W to 400W.

The adhesive of the embodiment of the application has the wave number of 1650 and 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 Is provided withAn infrared characteristic peak indicating the presence of an amide bond in the binder; at wave number of 3500 cm ^-1 The infrared characteristic peak shows that amino group exists in the adhesive and the wave number is 3300 cm ^-1 ~3400 cm ^-1 An infrared characteristic peak at the location, indicating the presence of hydrogen bonds in the binder. Therefore, the three-dimensional network structure taking the amide bond as a node and taking the hydrogen bond as a branched chain is formed in the binder molecule, which is more beneficial to improving the structural stability of the electrode material, so that the secondary battery shows more excellent electrochemical performance.

The second aspect of the embodiment of the application provides a preparation method of an adhesive, which comprises the following steps:

In the embodiment of the application, polyacrylic acid and terminal polyamino functional group monomer R- (NH) ₂ ) _a And (3) carrying out polymerization under the polymerization condition, wherein the terminal amino group in the bridging monomer is used for reacting with carboxyl in polyacrylic acid to form an amide bond, and the bridging monomer can react with a plurality of polyacrylic acids due to the terminal polyamino functional group of the bridging monomer, so that a polymer shown in the formula I can be formed, and the binder molecule is in a network crosslinking structure.

、、

XXI formula XXII

、、、

Formula XXIII formula XXIV formula XXV

、、、

Formula XXVI formula XXVII formula XXVIII

、、，

Formula XXIX formula XXX formula XXXI.

In formula XXVIII, b is a natural number of 5 or more. In some embodiments, b is a natural number of 5 to 10.

The bridging monomers provided by the embodiment of the application all comprise at least 2 terminal amino groups, and can form an adhesive with an alternating network structure with polyacrylic acid under the polymerization condition, so that the adhesive shows higher adhesive force; meanwhile, structures such as imino, sulfonic acid group, sulfonyl, thioether, oxyether and the like in the bridging monomer can also enable the adhesive to form intermolecular hydrogen bonds, so that the cohesiveness of the adhesive is further improved, and the surface stress of the electrode material is buffered; in addition, the electronegative atoms such as oxygen atoms, nitrogen atoms, sulfur atoms and the like contained in the bridging monomer can chelate transition metal ions, so that the structural stability of the electrode material is improved. Thus, the secondary battery has excellent electrochemical properties.

In some embodiments, the bridging unit comprises a conjugated structure, and the bridging unit comprises a conjugated structure The monomer has the chemical formula (NH) ₂ ) _x -A ₁ -A-A ₂ -(NH ₂ ) _y Wherein A comprises at least one of imino, oxyether, carbonyl, thioether, sulfoxide, sulfonyl, sulfonic acid and sulfonate; a is that ₁ And A ₂ Independently selected from C ₆ ~C ₁₅ At least one of aryl groups of (a); x is a natural number greater than or equal to 1, and y is a natural number greater than or equal to 1.

The bridging monomer provided by the embodiment of the application at least comprises 2 terminal amino groups for forming an amide bond with polyacrylic acid, so that the binder has a network crosslinking structure; conjugated aryl groups can increase the flexibility of the binder, whereby the binder exhibits higher adhesion and flexibility; simultaneously, the imino, oxyether, thioether and other groups contained in the bridging monomer can enable the adhesive to form intermolecular hydrogen bonds, so that the adhesive force is further improved.

In some embodiments, a comprises at least one of an imino group, an oxyether, a thioether, a sulfone group. The group A provided by the embodiment of the application enables the binder molecules to form intermolecular hydrogen bonds with rich types, the shearing force of the prepared positive electrode plate is higher, and the cohesiveness of the prepared negative electrode plate is better.

、、

Formula XXXII formula XXXIII

、、

Formula XXXIV formula XXXV

、、

Formula XXXVI formula XXXVII

、，

Formula XXXVIII formula XXXIX.

The bridging monomer shown in XXXII-XXXIX in the embodiment of the application can form an amide bond with polyacrylic acid, and the bridging monomer contains a plurality of terminal amino groups, so that the binder molecule has a network structure taking the amide bond as a node, and the binder has higher binding force.

In some embodiments, the polyacrylic acid is reacted with a bridging monomer R- (NH) ₂ ) _a The polymerization reaction is carried out specifically by the following steps:

step S10, polyacrylic acid and bridging monomer R- (NH) ₂ ) _a Dispersing in an organic solvent to form a mixed solution;

and step S20, under the protective atmosphere, adding an initiator into the mixed solution to perform polymerization reaction, thereby obtaining the adhesive.

In some embodiments, in step S10, the molar ratio of carboxyl groups to bridging monomers in the polyacrylic acid is 0.6-2.5: 1. under the proportion condition of the raw material components provided by the embodiment of the application, the polyacrylic acid contains sufficient carboxyl and reacts with bridging monomers containing terminal polyamino functional groups to form an amide bond, so that the formed adhesive has a network structure taking the amide bond as a node, and the viscosity of the adhesive is improved. Specifically, the ratio of carboxyl groups to bridging monomers in the polyacrylic acid may include, but is not limited to, 0.6:1, 1:1, 1.4:1, 1.8:1, 2.2:1, 2.5:1.

In some embodiments, in step S10, the organic solvent includes, but is not limited to, chloroform, ethanol, N-dimethylformamide, nitriles, or tetrahydrofuran.

In some embodiments, in step S10, the mass ratio of the starting materials including polyacrylic acid and bridging monomer to the organic solvent is 1: 20-80 parts. Under this ratio, it is more advantageous to uniformly disperse the polyacrylic acid and the bridging monomer in the organic solvent.

In some embodiments, in step S20, the conditions of the polymerization reaction include: the temperature is 60-90 ℃ and the time is 3-6 hours. Under the polymerization conditions provided by the embodiment of the application, polyacrylic acid is polymerized to form a binder with moderate molecular weight and a three-dimensional network structure. Specifically, the polymerization reaction temperature includes, but is not limited to 60 ℃, 70 ℃, 75 ℃, 80 ℃, 90 ℃. The polymerization time includes, but is not limited to, 3h, 4h, 5h, 6h.

In some embodiments, in step S20, the initiator comprises at least one of anhydrides, chloroformates, 4-N, N-lutidine (DMAP), 4-PPY, EDCI, HOBt, carbonium salts (HATU, HBTU, HCTU, TBTU).

A third aspect of the embodiment of the present application provides an electrode slurry including an electrode active material and a binder, the binder including the binder of the embodiment of the present application and/or the binder prepared by the preparation method of the binder of the embodiment of the present application.

In any of the embodiments, the mass percent of the binder may be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, or within a range consisting of any of the above values, based on the total mass of the components in the electrode slurry other than the solvent.

If the content of the additive is too small, it is difficult to exert a sufficient adhesive effect. On one hand, the adhesive can not fully disperse the conductive agent and the active substance, so that the resistance of the membrane of the pole piece is increased; on the contrary, if the content of the binder is too high, the viscosity of the electrode slurry is too high, so that the binder coating layer coated on the surface of the active material is too thick, the transmission of electrons and ions is influenced in the battery cycle process, the capacity of the pole piece is reduced, and the direct current impedance is increased.

It is understood that the current collector includes two surfaces opposite each other in the thickness direction thereof, and the active layer is stacked on either or both of the two surfaces of the current collector.

The electrode plate provided by the embodiment of the application contains the binder, so that the electrode active material, the conductive agent and other raw materials can be uniformly distributed and effectively coated on the particle surface of the active material, the electrode plate has higher binding force and flexibility, the dissolution of transition metal in the electrode material can be inhibited, and the structural stability of the electrode material is ensured, so that the secondary battery has higher cycle capacity retention rate, higher multiplying power performance and lower direct current impedance growth rate.

In some embodiments, the method for preparing the positive electrode sheet comprises the steps of:

and coating positive electrode slurry containing a binder, a positive electrode active material and a conductive agent on a positive electrode current collector, drying in an oven at 80-110 ℃, and rolling to obtain a positive electrode plate.

In some embodiments, the positive electrode active material may employ a positive electrode active material commonly used in the present application, and by way of example, the positive electrode active material may include at least one of the following materials: olivine structured lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. The lithium transition metal oxide comprises at least one of lithium cobaltate, nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, nickel cobalt manganese aluminum quaternary material, lithium iron phosphate, lithium manganese phosphate, lithium vanadium phosphate and lithium manganate.

In some embodiments, the positive electrode active material has the formula Li _a (A _b Co _c Mn _d Al _e )O ₂ Wherein A is at least one selected from Ni and Fe; a is more than or equal to 0.2 and less than or equal to 1.2, b is more than or equal to 0 and less than or equal to 1, c is more than or equal to 0 and less than or equal to 0.2, d is more than or equal to 0 and less than or equal to 0.2, e is more than or equal to 0 and less than or equal to 0.2, and b+c+d+e=1.

In some embodiments, the positive electrode active material is a high nickel layered metal oxide having the formula Li _a Ni _b Co _c Mn _d O ₂ A is more than 0.2 and less than or equal to 1.2, b is more than or equal to 0.8 and less than or equal to 1, c is more than or equal to 0 and less than or equal to 0.1, d is more than or equal to 0 and less than or equal to 0.1, and b+c+d=1.

The embodiment of the application does not limit the conductive agent in the anode slurry, and can be selected according to requirements. As an example, the conductive agent may include one or more of graphite, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the positive electrode current collector may be a metal foil or porous metal plate, such as aluminum foil, having good electrical and mechanical properties.

In some embodiments, the method of preparing the negative electrode sheet comprises the steps of:

and (3) coating the negative electrode slurry containing the binder, the negative electrode active material and the conductive agent on a negative electrode current collector, and drying and cold pressing to obtain a negative electrode plate.

In some embodiments, the negative electrode current collector may employ a metal foil or a composite current collector. The metal foil can be copper foil. The composite current collector can adopt a polymer material substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector can be formed on the surface of a high polymer material substrate such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene and the like through copper, copper alloy, nickel alloy, titanium alloy, silver and silver alloy.

In some embodiments, the negative active material may employ a negative active material for a battery, which is well known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like. The silicon-based material may include one or more of elemental silicon, silicon oxygen compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. The tin-based material may include one or more of elemental tin, tin oxide, and tin alloys. However, the embodiments of the present application are not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.

In some embodiments, the conductive agent in the negative electrode slurry includes at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

The term "shear force" refers to a phenomenon of relative dislocation deformation of a cross section of a material along the direction of application of a pair of transverse external forces (i.e., forces perpendicular to the application surface) that are closely spaced and of equal magnitude and are directed in opposite directions, and the forces that cause the material to undergo shear deformation are referred to as shear forces or shear forces. The section where shear deformation occurs is called a shear plane. Judging whether shearing is critical, and judging whether cross section of the material is staggered. In an embodiment of the application, shear force is used to characterize whether the positive electrode active layer is easily detached from the positive electrode current collector.

The positive electrode plate provided by the embodiment of the application contains the binder provided by the embodiment of the application, and the binder has a network crosslinking structure and can be effectively coated on the surface of the positive electrode active material, so that the positive electrode active layer is endowed with high shearing force, and is not easy to fall off from the positive electrode current collector in the use process.

The term "cohesive force" refers to the binding force between molecules at the interface of the adhesive and the object to be bonded. In the embodiment of the application, the binding force is used for representing the binding strength between the anode active layer and the anode current collector.

The negative electrode plate provided by the embodiment of the application contains the binder provided by the embodiment of the application, and the binder has a network crosslinking structure and can be effectively coated on the surface of a negative electrode material, so that the negative electrode plate is endowed with higher binding force, and a negative electrode active layer is not easy to fall off from a negative electrode current collector in the use process.

The secondary battery provided by the embodiment of the application has good electrochemical properties such as cycle stability, rate capability and the like.

The secondary battery is meant to include a battery case and a battery cell enclosed in the battery case. The shape of the secondary battery is not particularly limited, and may be cylindrical, square, or any other shape.

The secondary battery provided by the embodiment of the application comprises a positive electrode plate, a separation film and a negative electrode plate, wherein the separation film is arranged between the positive electrode plate and the negative electrode plate. Methods for manufacturing secondary batteries are well known. In some embodiments, the positive electrode tab, separator, and negative electrode tab and electrolyte may be assembled to form a secondary battery. For example, the positive electrode sheet, the separator and the negative electrode sheet may be wound or laminated to form an electrode assembly, the electrode assembly is placed in an outer package, dried and then injected with an electrolyte, and the secondary battery is obtained through vacuum packaging, standing, formation, shaping and other steps.

It should be appreciated that the electrolyte serves to conduct ions between the positive and negative electrode sheets. The application is not particularly limited in the kind of electrolyte, and can be selected according to the requirements. For example, the electrolyte may be liquid, gel-like or all-solid.

In some embodiments, the electrolyte includes an electrolyte salt and a solvent. Exemplary electrolyte salts may include, but are not limited to, one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate, and lithium tetrafluorooxalato phosphate. By way of example, the solvent may include, but is not limited to, one or more of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene 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 sulfone, and diethyl sulfone.

In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.

In some embodiments, the present application is not particularly limited in the kind of the separator, and any known porous structure separator having good chemical stability and mechanical stability may be used. Illustratively, the material of the barrier film may include, but is not limited to, one or more of fiberglass, nonwoven, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.

In some embodiments, the battery may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte as described above.

In some embodiments, the exterior package of the battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The outer package of the battery may also be a pouch, such as a pouch-type pouch. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module.

The battery module of the embodiment of the application comprises the secondary battery. Because the electrode plate of the secondary battery contains the binder provided by the embodiment of the application, the binder can be uniformly and effectively coated on the particle surface of the electrode material, the surface stress of the material is relieved, and the electrode interface is stabilized, so that the battery module has good electrochemical performance.

In some embodiments, a plurality of secondary batteries or a plurality of battery templates may also be assembled into a battery pack. The specific number of secondary batteries or battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

In a sixth aspect, an embodiment of the present application provides an electric device including the secondary battery according to the embodiment of the present application. The secondary battery in the embodiment of the application can be used as a power supply of an electric device and also can be used as an energy storage unit of the electric device. Therefore, the power utilization device provided by the embodiment of the application has long standby or endurance time.

The electric device may be, but is not limited to, a mobile device (e.g., a cellular phone, a notebook computer, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc. The power utilization device may select a secondary battery, a battery module, or a battery pack according to its use requirements.

Fig. 1 is a vehicle 1000 as one example. The vehicle 1000 may be a fuel oil vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or a range-extended vehicle. The interior of the vehicle 1000 is provided with a lithium ion battery 100, and the lithium ion battery 100 may be provided at the bottom or at the head or at the tail of the vehicle 1000. The lithium ion battery 100 may be used for power supply of the vehicle 1000, for example, the lithium ion battery 100 may serve as an operating power source of the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, the controller 200 being configured to control the lithium ion battery 100 to power the motor 300, for example, for operating power requirements during start-up, navigation, and travel of the vehicle 1000.

In some embodiments of the present application, lithium ion battery 100 may be used not only as an operating power source for vehicle 1000, but also as a driving power source for vehicle 1000, instead of or in part instead of fuel oil or natural gas, to provide driving power for vehicle 1000.

Referring to fig. 2, fig. 2 is an exploded view of a lithium ion battery 100 according to some embodiments of the present application. The lithium ion battery 100 includes a case 10 and a lithium ion battery cell 20, and the lithium ion battery cell 20 is accommodated in the case 10. The case 10 is used for providing an accommodating space for the lithium ion battery unit 20, and the case 10 may have various structures. In some embodiments, the case 10 may include an upper case 11 and a lower case 12, the upper case 11 and the lower case 12 being covered with each other, the upper case 11 and the lower case 12 together defining an enclosed space for accommodating the lithium ion battery cell 20. Of course, the case 10 formed by the upper case 11 and the lower case 12 may be of various shapes, such as a cylinder, a rectangular parallelepiped, etc. The plurality of battery cells 20 may be arranged in the battery case in any manner.

In the lithium ion battery 100, the number of the lithium ion battery cells 20 may be plural, and the plural lithium ion battery cells 20 may be connected in series or parallel or in series-parallel, and the series-parallel refers to that the plural lithium ion battery cells 20 are connected in series or parallel. The lithium ion battery monomers 20 can be directly connected in series or in parallel or in series-parallel, and then the whole formed by the lithium ion battery monomers 20 is accommodated in the box body 10; of course, the lithium ion battery 100 may also be a form of a lithium ion battery module formed by connecting a plurality of lithium ion battery cells 20 in series, parallel or series-parallel connection, and then connecting a plurality of lithium ion battery modules in series, parallel or series-parallel connection to form a whole, and then accommodating the whole in the case 10.

In some embodiments, referring to fig. 3, the exterior package of the battery cell 20 may include a housing 21 and a cover plate 23. The housing 21 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 21 has an opening communicating with the accommodation chamber, and the cover plate 23 is used to cover the opening to close the accommodation chamber. The positive electrode, separator, and negative electrode sheets included in the secondary battery according to the embodiment of the present application may be formed into the electrode assembly 22 through a winding process and/or a lamination process. The electrode assembly 22 is packaged in the receiving chamber. The electrolyte is impregnated in the electrode assembly 22. The number of the electrode assemblies 22 included in the battery cell 20 may be one or more, and may be adjusted according to actual needs.

The present application will be described in further detail with reference to specific examples and comparative examples. The experimental parameters not specified in the following specific examples are preferentially referred to the guidelines given in the present document, and may also be referred to the experimental manuals in the art or other experimental methods known in the art, or to the experimental conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention. It is understood that the apparatus and materials used in the following examples are more specific and in other embodiments may not be so limited; the weights of the relevant components mentioned in the embodiments of the present application may refer not only to the specific contents of the components, but also to the proportional relationship between the weights of the components, and thus, it is within the scope of the embodiments of the present application as long as the contents of the relevant components are scaled up or down according to the embodiments of the present application. Specifically, the weight described in the specification of the embodiment of the present application may be mass units known in the chemical field such as μ g, mg, g, kg.

Example 1

A binder, the method of making comprising the steps of:

step 1, dissolving polyacrylic acid containing 2 equivalents of carboxyl and a bridging monomer shown in a formula XXI containing 1 equivalent in chloroform, and stirring for 30min to obtain a mixed solution;

Formula XXI->

And 2, heating the mixed solution to 80 ℃, adding 1.1 equivalent of acetic anhydride, reacting for 5 hours under the protection of nitrogen, adding ammonia water to adjust the pH value to 6-8 after the reaction is finished, centrifuging, carrying out suction filtration, washing, and drying to obtain a binder, and marking the binder as a binder A.

Preparation of a lithium ion battery:

1) Positive pole piece: cathode active material (LiNi _0.9 Co _0.05 Mn _0.05 O ₂ ) 98g of conductive agent (super carbon black) 1g and binder (binder A) 1g, adding an appropriate amount of NMP (N-methylpyrrolidone)) Stirring and mixing at the rotating speed of 400-1000 r/s, wetting, kneading and dispersing to obtain cathode slurry, and regulating the viscosity to 8000-13500 mpa.s. And coating the prepared slurry on a current collector aluminum foil, and then drying in an oven at 80-110 ℃ to control the water content to be less than 150 ppm, so as to obtain the positive electrode plate.

2) Electrolyte solution: in an inert atmosphere glove box with water/oxygen less than 0.1ppm, mixing an organic solvent of Ethylene Carbonate (EC)/methyl ethyl carbonate (EMC)/diethyl carbonate (DEC) according to a ratio of 3:6:1 to form a basic electrolyte, and adding fully dried lithium hexafluorophosphate (LiPF) ₆ ) Stirring for 30min at normal temperature to completely dissolve lithium hexafluorophosphate and the basic electrolyte; then adding 3% of bis (trifluoromethylsulfonyl) calcium imide (Ca (TFSI) by an external method ₂ ) And obtaining electrolyte.

3) Negative pole piece: negative electrode material (hard carbon), binder (polyvinyl alcohol), conductive agent (SP-Li) according to 90:5:5, carrying out mixing ball milling on the mass of the anode material to obtain anode slurry, coating the anode slurry on the surface of a copper foil, rolling, and vacuum drying overnight at 110 ℃ to obtain the anode piece.

4) Isolation film: polyethylene film was used as the separator film.

Sequentially stacking the positive pole piece, the isolating film and the negative pole piece, so that the isolating film is positioned between the positive pole piece and the negative pole piece to play a role in isolation; then winding to obtain an electrode assembly, welding a tab for the electrode assembly, loading the electrode assembly into an aluminum shell, baking at 80 ℃ to remove water, injecting the electrolyte, and sealing; finally, the lithium ion secondary battery of the embodiment is obtained through the procedures of standing, hot and cold pressing, formation and shaping.

Example 2

A binder was prepared as in example 1, except that the bridging monomer shown in XXI was replaced with the bridging monomer shown in formula XXII, and the binder prepared was designated as binder B.

XX (X)II。

A lithium ion battery was identical to example 1 except that the binder a in the positive electrode sheet was replaced with the binder B.

Example 3

A binder was prepared as in example 1, except that the bridging monomer shown in XXI was replaced with the bridging monomer shown in formula XXIX, and the binder prepared was designated as binder C.

Formula XXIX. />

A lithium ion battery was identical to example 1 except that the binder a in the positive electrode sheet was replaced with the binder C.

Example 4

A binder was prepared as in example 1, except that the bridging monomer shown in XXI was replaced with the bridging monomer shown in formula XXX, and the binder prepared was designated as binder D.

Formula XXX.

A lithium ion battery was identical to example 1 except that the binder a in the positive electrode sheet was replaced with the binder D.

Example 5

A binder was prepared as in example 1, except that the bridging monomer shown in XXI was replaced with the bridging monomer shown in formula XXXIII, and the binder prepared was designated as binder E.

Formula XXXIII.

A lithium ion battery was similar to example 1 except that the binder a in the positive electrode sheet was replaced with the binder E.

Example 6

A binder was prepared as in example 1, except that the bridging monomer shown in XXI was replaced with the bridging monomer shown in formula XXXVIII, and the binder prepared was designated as binder F.

Formula XXXIII.

A lithium ion battery was identical to example 1 except that the binder a in the positive electrode sheet was replaced with the binder F.

Example 7

A binder was prepared as in example 1, except that the bridging monomer shown in XXI was replaced with the bridging monomer shown in formula XXXV, and the binder prepared was designated as binder G.

Formula XXXV.

A lithium ion battery was identical to example 1 except that the binder a in the positive electrode sheet was replaced with the binder G.

Example 8

A binder was prepared as in example 1, except that the bridging monomer shown in XXI was replaced with the bridging monomer shown in formula XXXIX, and the binder prepared was designated as binder H-1.

Formula XXXIX.

A lithium ion battery is the same as in example 1 except that the binder A in the positive electrode sheet is replaced with the binder H-1.

Example 9

A binder, similar to example 8, differs in that the equivalent ratio of carboxyl groups in the polyacrylic acid to the equivalent ratio of bridging monomers is 1:1, the prepared binder was designated H-2.

A lithium ion battery is the same as in example 8 except that the binder A in the positive electrode sheet is replaced with the binder H-2.

Example 10

A binder, similar to example 8, differs in that the equivalent ratio of carboxyl groups in the polyacrylic acid to the equivalent ratio of bridging monomers is 3:1, the adhesive prepared was designated H-3.

A lithium ion battery is the same as in example 8 except that the binder A in the positive electrode sheet is replaced with the binder H-3.

Example 11

An adhesive, as in example 8.

A lithium ion battery was similar to example 8, except that the content of binder H-1 in the positive electrode sheet was 0.1wt%.

Example 12

An adhesive, as in example 8.

A lithium ion battery was similar to example 8, except that the content of binder H-1 in the positive electrode sheet was 0.5wt%.

Example 13

An adhesive, as in example 8.

A lithium ion battery was similar to example 8, except that the content of binder H-1 in the positive electrode sheet was 2wt%.

Example 14

An adhesive, as in example 8.

A lithium ion battery was similar to example 8, except that the content of binder H-1 in the positive electrode sheet was 5wt%.

Example 15

An adhesive, as in example 8.

A lithium ion battery was similar to example 8, except that the content of binder H-1 in the positive electrode sheet was 6wt%.

Example 16

An adhesive, as in example 8.

A lithium ion battery is the same as in the embodiment 8, wherein the preparation method of the negative electrode plate is as follows:

negative electrode material (hard carbon), binder (binder H-1), conductive agent (SP-Li) according to 90:5:5, carrying out mixing ball milling on the mass of the anode material to obtain anode slurry, coating the anode slurry on the surface of a copper foil, rolling, and vacuum drying overnight at 110 ℃ to obtain the anode piece.

Example 17

An adhesive, as in example 8.

A lithium ion battery is similar to example 16, except that the mass content of the binder H-1 in the negative electrode sheet is 2wt%.

Example 18

An adhesive, as in example 8.

A lithium ion battery is the same as in example 16 except that the mass content of the binder H-1 in the negative electrode sheet is 1wt%.

Example 19

An adhesive, as in example 8.

A lithium ion battery is the same as in example 16 except that the mass content of the binder H-1 in the negative electrode sheet is 0.5wt%.

Comparative example 1

A lithium ion secondary battery, which is different from embodiment 16 in that: the binder H-1 used was replaced by polyvinylidene fluoride.

Comparative example 2

A lithium ion secondary battery, which is different from embodiment 16 in that: the binder H-1 used was replaced by polyacrylonitrile.

The pole pieces or lithium ion batteries prepared in the foregoing examples and comparative examples were subjected to the following characterization tests:

characterization of physical Properties

Testing

(1) Infrared spectrum (FTIR) and X-ray photoelectron spectroscopy (XPS) of the binder

A small amount of binder was taken and placed in a 100 ℃ oven for drying 12 h, and the functional group (NH ₂ -、-S=O-、CO-NH-、-SO ₂ -、SO ₃ (-) -; the corresponding XPS test method is the same, and is used for detecting the C-N, C-S, C = O, S = O, C-O bond, the content and the like in the adhesive.

(2) Positive pole piece shear force test

Taking a processed freshly dried positive pole piece, attaching a special double faced adhesive tape for die cutting, attaching abrasive paper on the other side, polishing and wiping a stainless steel plate, placing the stainless steel plate in an oven, heating at 80 ℃ for 5 min, fixing the stainless steel plate and a non-double faced adhesive tape area of the pole piece on a tensile testing machine, opening the tensile testing machine, setting parameters, starting up a test record, taking a maximum value Fs (N) of the tensile force, recording a stressed area S, and enabling the shearing strength Q=Fs/S (MPa).

(3) Negative pole piece adhesion test

The testing process comprises the following steps: taking a negative electrode plate to be tested, cutting a sample with the width of 30mm and the length of 100-160mm by using a blade, attaching the cut sample of the electrode plate to a double-sided adhesive tape, aligning the edge of the electrode plate with the edge of a steel plate, and ensuring that the electrode plate is adhered and leveled with the double-sided adhesive tape. When the length of the steel plate is longer than that of the pole piece, paper tape is inserted above or below the pole piece, the pole piece is fixed by using crepe rubber, the test surface is upward, and the pole piece is rolled back and forth 3-4 times by using a 2kg pressing roller. The adhesive force of the pole piece is measured on a tensile machine, and the numerical value N/m is recorded.

(4) Number average molecular weight test

The number average molecular weight test method comprises the following steps: the binder molecules were dissolved or dispersed in polar solvents ethanol, methanol, tetrahydrofuran, and the number average molecular weight of the binder was determined by Gel Permeation Chromatography (GPC).

The test results were as follows:

the adhesive prepared in example 1 was analyzed by infrared spectroscopy and was observed at 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 The corresponding characteristic peak of amide bond at 3500 cm ^-1 The corresponding amino characteristic peak, 1179 and 1179 cm ^-1 Corresponding C-S-C characteristic peak, 1600 and 1600 cm ^-1 C=o characteristic peak corresponding thereto, 2800 cm ^-1 ~3000 cm ^-1 Corresponding methyl characteristic peaks. Further, XPS analysis revealed that a characteristic peak of C-S, a c=o characteristic peak of 288.8eV, and a C-N characteristic peak of 285.7eV were observed at 286.8 eV.

The adhesive prepared in example 2 was analyzed by infrared spectroscopy and was observed at 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 The corresponding characteristic peak of amide bond at 3500 cm ^-1 Corresponding amino (-NH) ₂ ) Characteristic peak, 3310 cm ^-1 ~3350 cm ^-1 The corresponding-NH-characteristic peak. Further, XPS analysis revealed a C-N characteristic peak of 285.7 eV.

The adhesive prepared in example 3 was analyzed by infrared spectroscopyIt can be observed at 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 The corresponding characteristic peak of amide bond at 3500 cm ^-1 Corresponding amino (-NH) ₂ ) Characteristic peak 970 cm ^-1 Corresponding characteristic peak of sulfonyl at 1100 cm ^-1 Characteristic peaks of at-C-O-C-. Further, XPS analysis revealed that a characteristic peak of C-S was observed at 286.8eV, a characteristic peak of C-N at 285.7eV, and a characteristic peak of s=o at 168.4 eV.

The adhesive prepared in example 4 was observed to be at 650 cm by infrared spectroscopic analysis ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 The corresponding characteristic peak of amide bond at 1490 and 1490 cm ^-1 ，1440 cm ^-1 And 1395 cm ^-1 Characteristic absorption peaks of three sulfonates, 3650 and 3650 cm ^-1 -3600 cm ^-1 The corresponding hydroxyl (-OH) characteristic peak. Further, XPS analysis revealed that a characteristic peak of C-S was observed at 286.8eV, a characteristic peak of S=O at 168.4eV, and a characteristic peak of C-O at 285.4 eV.

The adhesive prepared in example 5 was analyzed by infrared spectroscopy and was observed at 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 The corresponding characteristic peak of amide bond at 3500 cm ^-1 Corresponding amino (-NH) ₂ ) Characteristic peak, 1400 cm ^-1 、1600 cm ^-1 At the characteristic peak of benzene ring, at 1100 cm ^-1 Characteristic peaks of at-C-O-C-. Further, XPS analysis revealed a characteristic peak of C-N at 285.7eV, and a characteristic peak of C-O at 285.4 eV.

The adhesive prepared in example 6 was analyzed by infrared spectroscopy and was observed at 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 The corresponding characteristic peak of amide bond at 1490 and 1490 cm ^-1 ，1440 cm ^-1 And 1395 cm ^-1 Characteristic absorption peaks of three sulfonates and 1400 cm ^-1 、1600 cm ^-1 Characteristic peak of benzene ring 590 cm ^-1 ~700 cm ^-1 The corresponding S-C peak. Further, XPS analysis revealed that a characteristic peak of s=o, 286.8, was observed at 168.4eVCharacteristic peaks of C-S were observed under eV.

The adhesive prepared in example 7 was analyzed by infrared spectroscopy and was observed at 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 The corresponding characteristic peak of amide bond at 3500 cm ^-1 The corresponding amino characteristic peak, 1179 and 1179 cm ^-1 Corresponding C-S-C characteristic peak, 1400 cm ^-1 -1600 cm ^-1 Characteristic peak of benzene ring 1092 cm ^-1 C=ch characteristic peak corresponding thereto 970 cm ^-1 Corresponding characteristic peak of sulfonyl. Further, XPS analysis revealed that a characteristic peak of s=o was observed at 168.4eV, and a characteristic peak of c—s was observed at 286.8 eV.

The adhesive prepared in example 8 was analyzed by infrared spectroscopy and was observed at 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 The corresponding characteristic peak of amide bond at 1490 and 1490 cm ^-1 ，1440 cm ^-1 And 1395 cm ^-1 Characteristic absorption peaks of three sulfonates and 1400 cm ^-1 、1600 cm ^-1 Is characterized by the characteristic peak of benzene ring. Further, XPS analysis revealed that a characteristic peak of s=o was observed at 168.4eV, and a characteristic peak of c—s was observed at 286.8 eV.

The binders prepared in examples 9 to 19 were identical to the infrared spectrum of the binders prepared in example 8.

The results of analysis of the number average molecular weights of the binders prepared in examples 1 to 10 are shown in Table 1 below. The prepared binders of examples 11 to 19 were identical to the number average molecular weight of the binders prepared in example 8.

TABLE 1

Electrochemical performance test

(1) DC impedance DCR test

Taking the battery core, carrying out capacity calibration, discharging to 50% of SOC (state of charge) by 1/3C, standing for 60 min, recording voltage V1, discharging (current I, A) by 4C for 30 s, and recording voltage V2, wherein DCR value is= (V1-V2)/I.

(2) Test of transition metal ion dissolution content after 1000 cycles

Taking a certain circulation for 1000 circles, washing the battery core with ethylene glycol dimethyl ether, drying, adding 1+1 aqua regia, digesting for 6 hours with microwaves (high temperature and high pressure (high temperature to 200 ℃), and measuring the contents of various transition metals contained in the cathode through an Inductively Coupled Plasma (ICP) emission spectrometer.

(3) Capacity retention test

Placing the assembled battery cell on an electrochemical test channel, circulating 1000 circles at 0.5C current and room temperature of 25 ℃ to read the capacity value C ¹ ₁₀₀₀ Comparing the initial first-turn capacity C ¹ ₀ By the formula: capacity retention = C ¹ ₁₀₀₀ /C ¹ ₀ *100% to obtain the capacity retention.

Electrochemical performance tests were performed on the lithium ion secondary batteries prepared in examples 1 to 19 and comparative examples 1 to 2. The test results are shown in table 2 below.

According to table 2, after the binder prepared by the embodiment of the application is added into the battery, the positive electrode plate/negative electrode plate shows higher binding force/shearing force, and can also effectively avoid the dissolution of transition metal ions, so that the structural stability of the electrode material is higher, and the lithium ion battery has better capacity retention rate and lower direct current impedance under the current density of 0.5C, and has excellent electrical performance.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application, and are intended to be included within the scope of the appended claims and description. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims

1. A binder comprising a polymer having the chemical formula I:

i is a kind of

Wherein, the R comprises an electron donating group;

2. The binder of claim 1 wherein the electron donating group comprises at least one of an imino group, an oxy ether, a carbonyl group, a thioether, a sulfoxide group, a sulfone group, a sulfonic acid group, and a sulfonate.

3. The adhesive according to claim 1 or 2, wherein R comprises at least one of a C1-C20 alkyl group, a C1-C20 hydroxyalkyl group, of a non-conjugated structure.

4. The binder of claim 3 wherein R comprises at least one of the groups of formulas II-XII:

、、

formula II and formula III

、、、

Formula IV formula V formula VI

、、、

Formula VII formula VIII formula IX

、、，

Formula X formula XI formula XII

Wherein, the wavy line in the formula II-XII represents the joint position of the amide bond in the formula I and R; in formula IX, b is a natural number of 5 or more.

5. The adhesive of claim 1 or 2, wherein R comprises a conjugated structure, and wherein R comprising a conjugated structure has the formula-a ₁ -A-A ₂ -wherein a comprises at least one of imino, oxy-ether, carbonyl, thioether, sulfoxide, sulfone, sulfonic acid, sulfonate; a is that ₁ And A ₂ Independently selected from C ₆ ~C ₁₅ At least one of the aryl groups of (a).

6. The binder of claim 5 wherein R comprising a conjugated structure comprises at least one of the groups represented by formulas XIII-XX:

、、

formula XIII formula XIV

、、

XV type XVI

、、

Formula XVII formula XVIII

、，

Formula XIX formula XX

Wherein, the wavy line in the formulas XIII to XX represents the bonding position of the amide bond in the formula I and R.

7. The binder of claim 1 or 2, wherein the molar ratio of amide bond to the electron donating group in the binder is 0.8-2.5: 1.

8. the binder of claim 1 or 2, wherein the binder has a number average molecular weight of 50W to 400W.

9. The binder of claim 1 or 2 wherein the binder has an infrared spectrum at wavenumber 1650 cm ^-1 ~1750 cm ^-1 、1250 cm ^-1 ~1350 cm ^-1 、3300 cm ^-1 ~3400 cm ^-1 、3500 cm ^-1 Has an infrared characteristic peak at the location of (a).

10. A method for preparing an adhesive, comprising the steps of:

polyacrylic acid and bridging monomer R- (NH) ₂ ) _a Carrying out a polymerization reaction to obtain the adhesive according to any one of claims 1-8, wherein a is a natural number greater than or equal to 2.

11. The method of preparing a binder of claim 10, wherein the bridging unit comprises a non-conjugated structure and the bridging unit comprising a non-conjugated structure comprises at least one of the compounds of formula XXI to formula XXXI:

、、

XXI formula XXII

、、、

Formula XXIII formula XXIV formula XXV

、、、

Formula XXVI formula XXVII formula XXVIII

、、，

Formula XXIX formula XXX formula XXXI

In formula XXVIII, b is a natural number of 5 or more.

12. The method of preparing a binder according to claim 10, wherein the bridging monomer comprises a conjugated structure, and the bridging monomer having a conjugated structure has a chemical formula (NH ₂ ) _x -A ₁ -A-A ₂ -(NH ₂ ) _y Wherein A comprises at least one of imino, oxyether, carbonyl, thioether, sulfoxide, sulfonyl, sulfonic acid and sulfonate; a is that ₁ And A ₂ Independently selected from C ₆ ~C ₁₅ At least one of aryl groups of (a); x is a natural number greater than or equal to 1, and y is a natural number greater than or equal to 1.

13. The method of preparing a binder of claim 12, wherein the bridging monomer comprising a conjugated structure comprises at least one of the compounds of formula XXXII to formula XXXIX:

、、

formula XXXII formula XXXIII

、、

Formula XXXIV formula XXXV

、、

Formula XXXVI formula XXXVII

、，

Formula XXXVIII formula XXXIX.

14. An electrode slurry comprising an electrode active material and a binder, wherein the binder comprises the binder of any one of claims 1 to 9 and/or the binder produced by the method for producing a binder of any one of claims 10 to 13.

15. The electrode slurry according to claim 14, wherein the binder is 0.5 to 5% by mass based on the total mass of the components other than the solvent in the electrode slurry.

16. The electrode slurry according to any one of claims 14 to 15, wherein the electrode active material is a positive electrode active material or a negative electrode active material.

17. An electrode sheet, characterized in that the electrode sheet comprises a current collector and an active layer arranged on at least one side of the surface of the current collector, wherein the raw materials for preparing the active layer comprise the binder as claimed in any one of claims 1 to 9; or the active layer is produced using the electrode slurry according to any one of claims 14 to 16.

18. The electrode sheet of claim 17, wherein the electrode sheet is a positive electrode sheet or a negative electrode sheet.

19. The electrode sheet of claim 18, wherein the shear force per unit length of active layer and current collector in the positive electrode sheet is not less than 0.7 MPa; or alternatively, the first and second heat exchangers may be,

the binding force between the active layer in the negative electrode plate and the current collector in unit length is not less than 7N/m.

20. A secondary battery comprising the electrode sheet of any one of claims 17 to 19.

21. An electric device comprising the secondary battery according to claim 20.