Adhesive composition for preparing pole piece, positive pole slurry and preparation method thereof, positive pole piece, battery and electric equipment

Abstract

The invention provides an adhesive composition for preparing a pole piece, positive pole slurry and a preparation method thereof, a positive pole piece, a battery and electric equipment, and belongs to the technical field of batteries. The adhesive composition for preparing the pole piece comprises a polymer adhesive and a curing agent, wherein the molecular structure of the polymer adhesive comprises a first structural unit and a second structural unit; a side chain of the first structural unit has a hydroxyl group, a side chain of the second structural unit has a carboxylate structure, and a side chain in a molecular structure of the polymer adhesive has a carboxylic ester group; the molecular structure of the curing agent has at least two isocyanate groups. The adhesive composition provided by the invention can improve the conditions that the active layer of the existing pole piece is easy to crack and the active layer of the pole piece is easy to separate from the current collector.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more specifically, to an adhesive composition for preparing a pole piece, a positive electrode slurry and a preparation method thereof, a positive electrode piece, a battery, and an electrical device. Background Art

[0002] In recent years, with the advancement of lithium-ion battery technology, lithium-ion batteries have been widely used in energy storage systems such as hydropower, thermal, wind, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. The performance of pole pieces is a key factor affecting the performance of lithium-ion batteries. Currently, pole pieces are prone to cracking in the active layer and separation of the active layer from the current collector. Summary of the Invention

[0003] In response to the deficiencies in the prior art, the present application provides an adhesive composition for preparing a pole piece, a positive electrode slurry and a preparation method thereof, a positive pole piece, a battery, and an electrical device to improve the existing situation in which the active layer of the pole piece is prone to cracking and the active layer of the pole piece is prone to detachment from the current collector.

[0004] In the first aspect, the present application provides an adhesive composition for preparing an electrode, the composition comprising a polymer adhesive and a curing agent; wherein the molecular structure of the polymer adhesive comprises a first structural unit and a second structural unit; the side chain of the first structural unit has a hydroxyl group, the side chain of the second structural unit has a carboxylate structure, and the side chain in the molecular structure of the polymer adhesive has a carboxylate group; the molecular structure of the curing agent has at least two isocyanate groups.

[0005] In the adhesive composition for preparing the electrode provided in the present application, the polymer adhesive can bond the active material and conductive agent and other components in the electrode together, and the at least two isocyanate groups in the curing agent can respectively undergo cross-linking reactions with the hydroxyl groups in the molecular structure of the two polymer adhesives, so that the curing agent and the polymer adhesive can form a cross-linked structure, which is beneficial to improving the cohesion of the electrode active layer; the carboxylate group in the polymer adhesive can improve the flexibility of the electrode active layer, which is beneficial to reducing the cracking of the electrode active layer; the carboxylate structure in the polymer adhesive can improve the adhesion between the electrode active layer and the current collector, which is beneficial to reducing the situation where the electrode active layer is separated from the current collector, and the presence of the carboxylate structure can further improve the cohesion of the active layer; and the isocyanate group in the curing agent, the hydroxyl group in the polymer adhesive, the carboxylate structure and the carboxylate structure can cooperate with each other to improve the limiting surface density of the electrode active layer and reduce the internal resistance of the electrode, which is beneficial to improving the energy density of the battery.

[0006] In some embodiments, the molecular structure of the polymer binder further includes a third structural unit, the side chains of which only have alkyl and carboxylate groups. The above solution can further improve the flexibility of the active layer of the electrode, which is conducive to further reducing cracking of the active layer of the electrode.

[0007] In some embodiments, the side chains in the molecular structure of the polymer binder have cyano groups and / or amide groups. The above solution can further improve the cohesion of the active layer of the electrode and the adhesion between the active layer of the electrode and the current collector, which is conducive to further reducing the cracking of the active layer of the electrode and the separation of the active layer of the electrode from the current collector.

[0008] In some embodiments, the main chain of the polymer binder's molecular structure consists solely of carbon-carbon single bonds. In this embodiment, the main chain of the polymer binder formed by carbon-carbon single bonds can improve the polymer binder's electrochemical stability and antioxidant capacity, thereby making it less susceptible to decomposition during the battery's charge and discharge processes.

[0009] In some embodiments, the molecular structure of the polymer binder includes a first structural unit and a second structural unit; the structural formula of the first structural unit is as follows: R1 is an alkyl group substituted with a hydroxyl group; the structural formula of the second structural unit is as follows: M1 is a metal cation. Alternatively, the molecular structure of the polymer binder includes a first structural unit, a second structural unit, and a third structural unit; the structural formula of the first structural unit is: R2 is a hydroxyl group or a hydroxyl-substituted alkyl group, and R3 is a hydroxyl-substituted alkyl group; the structural formula of the second structural unit is as follows: M2 is a metal cation; the structural formula of the third structural unit is as follows: The above solution is helpful to reduce the cracking of the active layer of the electrode and the separation of the active layer of the electrode from the current collector.

[0010] In some embodiments, the molecular structure of the polymer binder further includes at least one of a fourth structural unit and a fifth structural unit; wherein the structural formula of the fourth structural unit is as follows: R5 and R6 are each independently a hydrogen atom or an alkyl group; the structural formula of the fifth structural unit is as follows: R7 is a cyano group or an alkyl group substituted with a cyano group. The above solution is beneficial to further reduce the cracking of the active layer of the electrode and the separation of the active layer of the electrode from the current collector.

[0011] In some embodiments, the polymer binder includes at least one of poly(sodium acrylate-acrylamide-butyl acrylate-hydroxyethyl acrylate), poly(sodium acrylate-butyl acrylate-hydroxypropyl acrylate), poly(lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate), poly(sodium acrylate-butyl acrylate-hydroxyethyl acrylate), and poly(sodium acrylate-hydroxyethyl acrylate). Using the above-mentioned polymer binders can prevent the active layer of the electrode from cracking and from separating from the current collector.

[0012] In some embodiments, the side chain of the first structural unit has a hydroxyl group at its terminal end, and the curing agent has isocyanate groups at opposite ends of its molecular structure. In this embodiment, the isocyanate groups on the curing agent and the hydroxyl groups on the polymer binder provide less steric hindrance during the cross-linking reaction, facilitating a better cross-linking reaction between the curing agent and the polymer binder, thereby further enhancing the cohesion of the electrode active layer.

[0013] In some embodiments, the curing agent includes at least one of hexamethylene diisocyanate and polyisocyanate. The use of the above substances as the curing agent facilitates a better cross-linking reaction between the curing agent and the polymer binder, thereby further improving the cohesion of the active layer of the electrode.

[0014] In some embodiments, the mass ratio of the polymer binder to the curing agent is (1-30): 1. The above solution can prevent the active layer of the electrode from cracking and from separating from the current collector.

[0015] In a second aspect, the present application provides a method for preparing a positive electrode slurry, which adopts the adhesive composition for preparing an electrode provided in any one of the first aspects above; the method for preparing the positive electrode slurry comprises: firstly mixing a system containing a polymer adhesive, a conductive agent, a positive electrode active material and water to obtain a first system; and then adding a curing agent to the first system to perform a second mixing.

[0016] The preparation method of the positive electrode slurry provided in the present application adopts the adhesive composition provided in any one of the first aspects above, so that the prepared positive electrode active layer is not easy to crack and the positive electrode active layer is not easy to separate from the positive electrode current collector. It can also make the limiting surface density of the positive electrode active layer higher and the internal resistance of the positive electrode sheet lower, which is beneficial to improving the energy density of the battery.

[0017] In some embodiments, the mass ratio of the polymer binder to the positive electrode active material is 1:(40-55).

[0018] In a third aspect, the present application provides a positive electrode slurry, which is prepared using the positive electrode slurry preparation method provided in any one of the second aspects above.

[0019] In a fourth aspect, the present application provides a positive electrode plate, which includes a positive electrode collector and a positive electrode active layer covering at least one surface in the thickness direction of the positive electrode collector; wherein the positive electrode active layer includes a solidified product of the positive electrode slurry provided in the third aspect above; the solidified product contains a product of a cross-linking reaction between a polymer binder and a curing agent.

[0020] The positive electrode active layer of the positive electrode plate provided in the present application contains the product of the cross-linking reaction between a curing agent and a polymer binder, which can make the positive electrode active layer of the positive electrode plate less likely to crack and the positive electrode active layer less likely to separate from the positive electrode current collector. It can also make the limiting surface density of the positive electrode active layer higher and the internal resistance of the positive electrode plate lower, which is beneficial to improving the energy density of the battery.

[0021] In some embodiments, the product has the following structural formula:

[0022] Wherein, a, b, g and h are all greater than 0, x, y, c, d, e, i, j and k are all greater than or equal to 0; A, B, C, D, E, G, H, I, J and K are the main chain skeletons of the polymer; R b and R h Both contain carboxylate structures; R c and R i All contain carboxylate groups; R d and R j Both contain amide groups; R e and R k All contain cyano group; R f is a linking group; R a and R g Each independently selected from an alkylene group or a structure containing a carboxylate group; when x is 0 or R a When y is 0 or R g When it is an alkylene group, i>0. The above scheme can make the positive electrode active layer of the positive electrode plate less likely to crack and the positive electrode active layer less likely to separate from the positive electrode current collector. It can also make the limiting surface density of the positive electrode active layer higher and the internal resistance of the positive electrode plate lower, which is beneficial to improving the energy density of the battery.

[0023] In some embodiments, the product has the following structural formula:

[0024] Where a, b, g, and h are all greater than 0, and x, y, c, d, e, i, j, and k are all greater than or equal to 0; R b and R h Both contain carboxylate structures; R c and R i All contain carboxylate groups; R d and R j Both contain amide groups; R eand R k All contain cyano group; R f is a linking group; R a and R g Each independently selected from an alkylene group or a structure containing a carboxylate group; when x is 0 or R a When y is 0 or R g When the alkylene group is an alkylene group, i>0. The above scheme can make the positive electrode active layer of the positive electrode sheet less likely to crack and less likely to separate from the positive electrode current collector. It can also make the limiting surface density of the positive electrode active layer higher and the internal resistance of the positive electrode sheet lower, which is beneficial to improving the energy density of the battery. The main chain skeleton of the product has only carbon-carbon single bonds, which can improve the electrochemical stability and antioxidant ability of the polymer binder, thereby making the polymer binder less likely to decompose during the charge and discharge process of the battery.

[0025] In some embodiments, c and i>0, and R c and R i The structural formulas are R l is an alkyl group; or / and, R f is a straight chain alkyl group; or / and, R b and R h The structural formulas are M3M3 is a metal cation; or / and, R d and R j The structural formulas are R m and R n are each independently a hydrogen atom or an alkyl group; or / and, R e and R k The structural formulas are R o is cyano or cyano-substituted alkyl; or / and, R a and R g The structural formulas are R p is an alkylene group, and R a and R g The carboxylate group in is connected to the main chain of the product; or / and, d and j are both greater than 0; or / and, e and k are both greater than 0. The above scheme is conducive to further reducing the cracking of the positive electrode active layer and the separation of the positive electrode active layer from the positive electrode current collector.

[0026] In a fifth aspect, the present application provides a battery comprising the positive electrode sheet provided in any one of the fourth aspects above.

[0027] In a sixth aspect, the present application provides an electrical device, which includes the battery provided in the fifth aspect.

[0028] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0030] Figure 1 A schematic structural diagram of a vehicle provided for some embodiments of the present application.

[0031] Figure 2 Schematic diagram of the exploded structure of the battery provided in some embodiments of the present application.

[0032] Figure 3 A schematic structural diagram of a battery cell provided in some embodiments of the present application.

[0033] Figure 4 An exploded view of a battery cell provided in some embodiments of the present application.

[0034] Figure 5 A schematic structural diagram of the electrode assembly provided in some embodiments of the present application.

[0035] Figure 6 This is the infrared spectrum of the polymer adhesive prepared in Example 1 of the present application.

[0036] Figure 7 This is an infrared spectrum of the cross-linked product after the cross-linking reaction between the polymer adhesive prepared in Example 1 of the present application and the curing agent.

[0037] Icons: 1000-vehicle; 100-battery; 10-housing; 11-accommodation space; 12-first part; 13-second part; 20-battery cell; 21-housing; 211-opening; 22-end cover assembly; 221-end cover; 222-electrode terminal; 23-electrode assembly; 231-positive electrode sheet; 232-negative electrode sheet; 233-separation membrane; 24-current collecting member; 25-insulating protection member; 200-controller; 300-motor. DETAILED DESCRIPTION

[0038] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0040] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0041] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0042] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0043] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0044] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0045] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0046] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0047] Power batteries can be lithium-ion batteries. During the charging process, lithium ions are released from the positive active material in the positive active layer of the positive electrode plate, transported through the electrolyte, and then embedded in the negative active layer of the negative electrode plate. Currently, the cohesive force of the active layer of the plate is low, and the adhesion between the active layer and the current collector is low, resulting in the active layer being prone to cracking and separation from the positive current collector.

[0048] Based on the above considerations, in order to simultaneously improve the existing situation in which the active layer of the electrode is prone to cracking and the active layer of the electrode is prone to detachment from the current collector, the present application designs an adhesive composition for preparing the electrode, which composition includes a polymer adhesive and a curing agent; wherein, the molecular structure of the polymer adhesive includes a first structural unit and a second structural unit; the side chain of the first structural unit has a hydroxyl group, the side chain of the second structural unit has a carboxylate structure, and the side chain in the molecular structure of the polymer adhesive has a carboxylate group; the molecular structure of the curing agent has at least two isocyanate groups.

[0049] In the adhesive composition for preparing the electrode provided in the present application, the polymer adhesive can bond the active material and conductive agent and other components in the electrode together, and the at least two isocyanate groups in the curing agent can respectively undergo a cross-linking reaction with the hydroxyl groups in the molecular structure of the two polymer adhesives, so that the curing agent and the polymer adhesive can form a cross-linked structure, which is beneficial to improving the cohesion of the electrode active layer. The carboxylate group in the polymer adhesive can improve the flexibility of the electrode active layer, which is beneficial to reducing the cracking of the electrode active layer. The presence of the carboxylate structure can further improve the cohesion of the active layer; the carboxylate structure in the polymer adhesive can improve the adhesion between the electrode active layer and the current collector, which is beneficial to reducing the separation of the electrode active layer from the current collector; in addition, the isocyanate group in the curing agent, the hydroxyl group in the polymer adhesive, the carboxylate structure and the carboxylate structure can cooperate with each other to improve the ultimate surface density of the electrode active layer and reduce the internal resistance of the electrode, which is beneficial to improving the energy density of the battery.

[0050] The adhesive composition for preparing electrode sheets provided above can be used to prepare electrode sheet slurry (e.g., positive electrode slurry), which can then be used to prepare electrode sheets (e.g., positive electrode sheets). The electrode sheets can be assembled into batteries, which can be battery cells, modules, battery packs, etc., and the batteries can be used, but not limited to, in electrical equipment such as vehicles, ships, or aircraft. The batteries disclosed in this application can be used to form a power supply system for such electrical equipment.

[0051] The embodiments of the present application provide an electrical device that uses a battery as a power source. The electrical device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle may be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft. The electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. The electric tools may include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0052] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0053] Please refer to Figure 1 , Figure 1This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of the present application. A battery 100 is disposed within the vehicle 1000, and the battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000, for example, as the operating power source of the vehicle 1000.

[0054] The vehicle 1000 may further include a controller 200 and a motor 300 . The controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0055] In some embodiments of the present application, the battery 100 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0056] Figure 2 This is a schematic diagram of the exploded structure of the battery 100 provided in some embodiments of the present application. Figure 2 The battery 100 includes a box body 10 and a battery cell 20 , and the battery cell 20 is accommodated in the box body 10 .

[0057] The housing 10 is used to provide a storage space 11 for the battery cells 20. In some embodiments, the housing 10 may include a first portion 12 and a second portion 13, which overlap to define the storage space 11 for accommodating the battery cells 20. Of course, the connection between the first portion 12 and the second portion 13 can be sealed by a seal (not shown), such as a sealing ring, sealant, or the like.

[0058] The first part 12 and the second part 13 can be in various shapes, such as a cuboid, a cylinder, etc. The first part 12 can be a hollow structure with one side open to form a receiving cavity for accommodating the battery cell 20, and the second part 13 can also be a hollow structure with one side open to form a receiving cavity for accommodating the battery cell 20. The open side of the second part 13 covers the open side of the first part 12, thereby forming a box body 10 with a receiving space 11. Of course, if Figure 2 As shown, the first part 12 may be a hollow structure with one side open, and the second part 13 may be a plate-like structure. The second part 13 covers the open side of the first part 12 to form a box body 10 with an accommodating space 11.

[0059] In the battery 100, there can be one or more battery cells 20. If there are multiple battery cells 20, the multiple battery cells 20 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 can be housed within the housing 10. Alternatively, multiple battery cells 20 can be first connected in series, in parallel, or in a hybrid connection to form a battery module, and then the multiple battery modules can be connected in series, in parallel, or in a hybrid connection to form a single unit and housed within the housing 10. The battery cells 20 can be cylindrical, flat, rectangular, or other shapes. Figure 2 The example shows a case where the battery cell 20 is square.

[0060] In some embodiments, the battery 100 may further include a busbar component (not shown), and the multiple battery cells 20 may be electrically connected via the busbar component to achieve series connection, parallel connection, or mixed connection of the multiple battery cells 20 .

[0061] Figure 3 This is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of the present application. Figure 4 This is an exploded view of a battery cell 20 provided in some embodiments of the present application. Figure 3 and Figure 4 The battery cell 20 may include a housing 21 , an end cap assembly 22 and an electrode assembly 23 . The housing 21 has an opening 211 , the electrode assembly 23 is accommodated in the housing 21 , and the end cap assembly 22 is used to cover the opening 211 .

[0062] The shape of the housing 21 can be determined according to the specific shape of the electrode assembly 23. For example, if the electrode assembly 23 is a rectangular parallelepiped structure, the housing 21 can also be a rectangular parallelepiped structure. Figure 3 and Figure 4 The case where the housing 21 and the electrode assembly 23 are square is exemplarily shown.

[0063] The shell 21 may be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0064] The end cap assembly 22 includes an end cap 221 and an electrode terminal 222. The end cap assembly 22 is used to seal the opening 211 of the outer shell 21 to form a sealed installation space (not shown), which is used to accommodate the electrode assembly 23. The installation space is also used to accommodate an electrolyte, such as an electrolyte. The end cap assembly 22 serves as a component for outputting the electrical energy of the electrode assembly 23. The electrode terminal 222 in the end cap assembly 22 is used to electrically connect to the electrode assembly 23, that is, the electrode terminal 222 is electrically connected to the tab of the electrode assembly 23. For example, the electrode terminal 222 is connected to the tab through the current collecting member 24 to achieve electrical connection between the electrode terminal 222 and the tab.

[0065] It should be noted that the number of openings 211 of the outer shell 21 can be one or two. If the number of openings 211 of the outer shell 21 is one, the number of end cap assembly 22 can also be one, and two electrode terminals 222 can be provided in the end cap assembly 22. The two electrode terminals 222 are respectively used to electrically connect to the positive electrode tab and the negative electrode tab of the electrode assembly 23. If the number of openings 211 of the outer shell 21 is two, for example, the two openings 211 are provided on opposite sides of the outer shell 21, the number of end cap assemblies 22 can also be two, and the two end cap assemblies 22 are respectively covered at the two openings 211 of the outer shell 21. In this case, the electrode terminal 222 in one end cap assembly 22 can be a positive electrode terminal, which is used to electrically connect to the positive electrode tab of the electrode assembly 23; and the electrode terminal 222 in the other end cap assembly 22 can be a negative electrode terminal, which is used to electrically connect to the negative electrode tab of the electrode assembly 23.

[0066] In some embodiments, as Figure 4 As shown, the battery cell 20 may further include an insulating protective member 25 fixed to the periphery of the electrode assembly 23, and the insulating protective member 25 is used to insulate and isolate the electrode assembly 23 from the housing 21. Exemplarily, the insulating protective member 25 is a tape bonded to the periphery of the electrode assembly 23. In some embodiments, there are multiple electrode assemblies 23, and the insulating protective member 25 is arranged around the periphery of the multiple electrode assemblies 23, and the multiple electrode assemblies 23 are formed into an integral structure to maintain the structural stability of the electrode assembly 23. Among them, the electrode assembly 23 can be a wound electrode assembly or a laminated electrode assembly, and the embodiments of the present application are not limited thereto.

[0067] Figure 5 For a schematic diagram of the structure of the electrode assembly provided in some embodiments of the present application, please refer to Figure 5 The electrode assembly 23 includes a positive electrode sheet 231, a negative electrode sheet 232 and a separator 233. The separator 233 is arranged between the positive electrode sheet 231 and the negative electrode sheet 232. The electrolyte is located in the installation space and fills the gap in the electrode assembly 23.

[0068] This application has no particular restrictions on the isolation membrane and the electrolyte.

[0069] As for the isolation membrane, the isolation membrane may be a PP (polypropylene, polypropylene) porous membrane, a PE (polyethylene, polyethylene) porous membrane, a polyimide porous membrane, or a porous membrane formed by a composite of multiple polymers.

[0070] For the coating of the electrolyte, the electrolyte includes a sodium salt and a non-aqueous solvent, or the electrolyte includes a lithium salt and a non-aqueous solvent; wherein the sodium salt may include at least one of NaPF6, NaClO4, NaBCl4, NaSO3CF3, or Na(CH3)C6H4SO3; the present application has no particular limitation on the concentration of the sodium salt in the electrolyte, as long as the purpose of the present application can be achieved. The lithium salt may include at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, Li2SiF6, lithium bis(oxalatoborate) (LiBOB), or lithium difluoroborate; the present application has no particular limitation on the concentration of the lithium salt in the electrolyte, as long as the purpose of the present application can be achieved. The present application has no particular limitation on the above-mentioned non-aqueous solvent, as long as the purpose of the present application can be achieved, for example, it may include but is not limited to at least one of carbonate compounds, carboxylate compounds, ether compounds or other organic solvents; the above-mentioned carbonate compounds may include but are not limited to at least one of chain carbonate compounds, cyclic carbonate compounds or fluorocarbonate compounds; the above-mentioned chain carbonate compounds may include but are not limited to at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC) or methylethyl carbonate (MEC); the above-mentioned cyclic carbonates may include but are not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) or vinylethylene carbonate (VEC); the fluorocarbonate compounds may include but are not limited to fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2-tetrafluoroethylene carbonate At least one of fluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate or trifluoromethylethylene carbonate; the above-mentioned carboxylic acid ester compound may include but is not limited to at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanoic acid, valerolactone or caprolactone; the above-mentioned ether compound may include but is not limited to at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanoic acid, valerolactone or caprolactone; the above-mentioned ether compound may include but Not limited to at least one of dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran; the above-mentioned other organic solvents may include but are not limited to at least one of dimethyl sulfoxide, 1,2-dioxolane, cyclopentane, methylcyclopentane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate or trioctyl phosphate.

[0071] The positive electrode sheet includes a positive electrode current collector and a positive electrode active layer covering at least one surface of the positive electrode current collector in a thickness direction.

[0072] The materials of the positive electrode current collector may include aluminum foil, foamed aluminum, aluminum composite current collector (a current collector with a polymer support layer in the middle and aluminum metal layers on both surfaces of the support layer), nickel foil, foamed nickel, etc.

[0073] The conductive agent in the positive electrode active layer is selected from at least one of conductive carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotube, graphene, activated carbon, graphite flakes, graphite particles and mesophase carbon microbeads.

[0074] The positive electrode active material in the positive electrode active layer is selected from one or more of lithium iron phosphate, lithium manganese phosphate, lithium cobalt phosphate, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.

[0075] In the present application, the adhesive in the positive electrode active layer adopts the adhesive composition for preparing the electrode provided in the present application, which comprises a polymer adhesive and a curing agent; wherein, the molecular structure of the polymer adhesive comprises a first structural unit and a second structural unit; the side chain of the first structural unit has a hydroxyl group, the side chain of the second structural unit has a carboxylate structure, and the side chain in the molecular structure of the polymer adhesive has a carboxylate group; the molecular structure of the curing agent has at least two isocyanate groups.

[0076] It should be noted that, before the adhesive composition provided by the user for preparing the electrode is used to prepare the positive electrode slurry, the curing agent and the polymer adhesive are stored separately.

[0077] Among them, the structural unit refers to the combination of atoms that constitute the polymer chain and determine how the polymer structure is connected in a certain way. It is the smallest basic unit in which the chemical composition and structure can be repeated on the polymer chain.

[0078] The side chain of a structural unit refers to a side chain structure connected to the main chain of the structural unit.

[0079] Carboxylate structure refers to the structure formed by the electrostatic combination of carboxyl anions and metal cations.

[0080] The fact that a side chain in the molecular structure of the polymer adhesive has a carboxylate group means that the side chain on any structural unit in the molecular structure of the polymer adhesive may have a carboxylate group, and the aforementioned any structural unit may be the first structural unit, the second structural unit, or any other structural unit excluding the first structural unit and the second structural unit.

[0081] In the adhesive composition for preparing the electrode provided in the present application, the polymer adhesive can bond the positive electrode active material and components such as the conductive agent in the positive electrode plate together, and at least two isocyanate groups in the curing agent can respectively undergo cross-linking reactions with the hydroxyl groups in the molecular structure of the two polymer adhesives, so that the curing agent and the polymer adhesive can form a cross-linked structure, which is beneficial to improving the cohesion of the positive electrode active layer.

[0082] In the adhesive composition for preparing pole pieces provided in the present application, the carboxylate group in the polymer adhesive can improve the flexibility of the positive electrode active layer, which is beneficial to reducing cracking of the positive electrode active layer.

[0083] In the adhesive composition for preparing electrode sheets provided in the present application, the carboxylate structure in the polymer adhesive is conducive to the dispersion and suspension of solid particles such as the positive electrode active material in the positive electrode slurry, and the carboxylate structure is conducive to combining with active groups such as hydroxyl groups on the current collector through hydrogen bonding, which can improve the adhesion between the positive electrode active layer and the current collector, and is conducive to reducing the situation where the positive electrode active layer is separated from the current collector; in addition, the carboxylate structure is also conducive to combining with the active groups on the positive electrode active material through hydrogen bonding, which is conducive to further improving the cohesion of the positive electrode active layer.

[0084] In addition, in the adhesive composition for preparing the electrode provided in the present application, the isocyanate group in the curing agent, the hydroxyl group, the carboxylate structure and the carboxylate structure in the polymer adhesive can cooperate with each other to increase the limiting surface density of the positive electrode active layer and reduce the internal resistance of the positive electrode sheet, which is beneficial to improve the energy density of the battery prepared using the positive electrode sheet.

[0085] In some embodiments, the molecular structure of the polymer binder further includes a third structural unit, and the side chain of the third structural unit only has an alkyl group and a carboxylate group; compared with the situation where carboxylate and hydroxyl groups coexist in the same side chain, the presence of side chains only having alkyl groups and carboxylate groups in the molecular structure of the polymer binder can further improve the flexibility of the positive electrode active layer, which is beneficial to further reduce the cracking of the positive electrode active layer.

[0086] In some embodiments, the side chain in the molecular structure of the polymer binder has a cyano group; the cyano group is conducive to combining with the inactive group on the positive electrode active material through a dipole effect, and the cyano group is also conducive to combining with the inactive group sites on the current collector through a dipole effect, thereby further improving the cohesion of the positive electrode active layer and the adhesion between the positive electrode active layer and the current collector, and further reducing the cracking of the positive electrode active layer and the separation of the positive electrode active layer from the current collector; in addition, compared with the carboxylate structure, the cyano group has a greater adhesion force to the current collector, which is more conducive to reducing the separation of the positive electrode active layer from the current collector.

[0087] In some embodiments, the side chain in the molecular structure of the polymer binder has an amide group; the presence of the amide group can increase the cohesive force of the positive electrode active layer and the adhesion between the positive electrode active layer and the current collector, thereby reducing the cracking of the positive electrode active layer and the separation of the positive electrode active layer from the current collector; in addition, compared with the amide group, the cohesive force of the positive electrode active layer and the adhesion between the positive electrode active layer and the current collector caused by the carboxylate structure and the cyano group are greater.

[0088] In some embodiments, the main chain of the polymer binder's molecular structure consists solely of carbon-carbon single bonds. The carbon-carbon single bonds forming the main chain of the polymer binder improve the polymer binder's electrochemical stability and antioxidant capacity, thereby making the polymer binder less susceptible to decomposition during the battery's charge and discharge processes.

[0089] In some embodiments, the molecular structure of the polymer binder is the first example. In the first example, the molecular structure of the polymer binder includes a first structural unit and a second structural unit. The structural formula of the first structural unit is as follows: R1 is an alkyl group substituted with a hydroxyl group; the structural formula of the second structural unit is as follows: M1 is a metal cation. The above solution is conducive to reducing the cracking of the positive electrode active layer and the separation of the positive electrode active layer from the current collector.

[0090] Furthermore, in some embodiments, R1 is a C1-C5 alkyl group substituted with a hydroxyl group; illustratively, R1 is a propyl group substituted with a hydroxyl group or an ethyl group substituted with a hydroxyl group.

[0091] As an example, M1 is lithium ion or sodium ion.

[0092] In some embodiments, the molecular structure of the polymer binder includes a first structural unit, a second structural unit, and a third structural unit; the structural formula of the first structural unit is: R2 is a hydroxyl group or a hydroxyl-substituted alkyl group, and R3 is a hydroxyl-substituted alkyl group; the structural formula of the second structural unit is as follows: M2 is a metal cation; the structural formula of the third structural unit is as follows: The above solution is conducive to reducing the cracking of the positive electrode active layer and the separation of the positive electrode active layer from the current collector.

[0093] Furthermore, in some embodiments, R2 is a hydroxyl group or a C1-C5 alkyl group substituted with a hydroxyl group; illustratively, R2 is a hydroxyl group, a propyl group substituted with a hydroxyl group, or an ethyl group substituted with a hydroxyl group.

[0094] In some embodiments, R3 is a C1-C5 alkyl group substituted with a hydroxyl group; for example, R3 is a propyl group substituted with a hydroxyl group or an ethyl group substituted with a hydroxyl group.

[0095] As an example, M2 is lithium ion or sodium ion, etc.

[0096] In some embodiments, R4 is a C1-C5 alkyl group; for example, R4 is a methyl group, an ethyl group, a propyl group, or a butyl group.

[0097] In some embodiments, the molecular structure of the polymer binder further includes at least one of a fourth structural unit and a fifth structural unit; wherein the structural formula of the fourth structural unit is as follows: R5 and R6 are each independently a hydrogen atom or an alkyl group; the structural formula of the fifth structural unit is as follows: R7 is a cyano group or a cyano-substituted alkyl group. The molecular structure of the polymer binder includes the fourth structural unit and / or the fifth structural unit, which is beneficial to further reduce the cracking of the positive electrode active layer and the separation of the positive electrode active layer from the current collector.

[0098] Furthermore, in some embodiments, R5 and R6 are each independently a hydrogen atom or a C1-C5 alkyl group; illustratively, R5 and R6 are both hydrogen atoms.

[0099] In some embodiments, R7 is cyano or a C1-C5 alkyl group substituted with cyano; illustratively, R7 is cyano.

[0100] In some embodiments, the polymer binder includes at least one of poly(sodium acrylate-acrylamide-butyl acrylate-hydroxyethyl acrylate), poly(sodium acrylate-butyl acrylate-hydroxypropyl acrylate), poly(sodium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate), poly(sodium acrylate-butyl acrylate-hydroxyethyl acrylate), and poly(sodium acrylate-hydroxyethyl acrylate). Using the above polymer binders can prevent the positive electrode active layer from cracking and from separating from the current collector.

[0101] It should be noted that the polymer adhesive is not limited to the above substances, as long as the polymer adhesive includes a first structural unit with a hydroxyl group on the side chain, a second structural unit with a carboxylate structure on the side chain, and the side chain in the molecular structure of the polymer adhesive has a carboxylate group.

[0102] In some embodiments, the side chain of the first structural unit has a hydroxyl group at its terminal end, and the curing agent has isocyanate groups at opposite ends of its molecular structure. This approach can minimize steric hindrance during the cross-linking reaction between the isocyanate groups on the curing agent and the hydroxyl groups on the polymer binder, facilitating a better cross-linking reaction between the curing agent and the polymer binder, and further enhancing the cohesive force of the positive electrode active layer.

[0103] In some embodiments, the curing agent includes at least one of hexamethylene diisocyanate and polyisocyanate. The use of the above-mentioned curing agent facilitates a better cross-linking reaction between the curing agent and the polymer binder, thereby further improving the cohesion of the positive electrode active layer.

[0104] In some embodiments, the mass ratio of the polymer binder to the curing agent is (1-30):1; this can prevent the positive electrode active layer from cracking and from separating from the current collector.

[0105] As an example, the mass ratio of the polymer binder to the curing agent can be any value among 1:1, 2:1, 5:2, 4:1, 20:3, 20:1, 25:1, 27:1 and 30:1, or a range between any two values.

[0106] Furthermore, in some embodiments, the mass ratio of the polymer binder to the curing agent is (2-20):1; this can result in a higher cohesive force of the prepared positive electrode active layer, a higher adhesion force between the positive electrode active layer and the current collector, a higher toughness of the positive electrode active layer, a higher limiting surface density of the positive electrode active layer, and a lower internal resistance of the positive electrode sheet.

[0107] In the present application, the preparation method of the positive electrode slurry adopts the adhesive composition for preparing the electrode provided above; the preparation method of the positive electrode slurry includes: firstly mixing a system containing a polymer adhesive, a conductive agent, a positive electrode active material and water to obtain a first system; and then adding a curing agent to the first system for a second mixing.

[0108] The preparation method of the positive electrode slurry provided in the present application adopts the adhesive composition provided above, so that the prepared positive electrode active layer is not easy to crack and the positive electrode active layer is not easy to separate from the positive electrode current collector. It can also make the limiting surface density of the positive electrode active layer higher and the internal resistance of the positive electrode sheet lower, which is beneficial to improving the energy density of the battery prepared using the modified positive electrode material.

[0109] In the preparation method of the positive electrode slurry provided in the present application, the polymer binder is first mixed with the other components in the positive electrode slurry, so that the polymer binder can fully contact and bond with the other components in the positive electrode slurry; and then the curing agent is added, which is beneficial to avoid the situation where the curing agent first undergoes a cross-linking reaction with the polymer binder and cannot effectively bond with the other components in the positive electrode slurry, and can improve the cohesion of the positive electrode active layer.

[0110] If the polymer binder and curing agent are added at the same time, the polymer binder and curing agent may undergo a rapid cross-linking reaction, causing the system to solidify, making the polymer binder unable to effectively bond to other components in the positive electrode slurry, and also not conducive to coating the prepared positive electrode slurry on the surface of the current collector.

[0111] If the curing agent is added first and the polymer binder is added later, the polymer binder will quickly undergo a cross-linking reaction with the curing agent after addition, causing the system to solidify. This will also result in the polymer binder being unable to effectively bond to other components in the positive electrode slurry, and is not conducive to coating the prepared positive electrode slurry on the surface of the current collector.

[0112] In addition, the present application adopts the method of "first mixing the polymer binder with other components in the positive electrode slurry, and then adding the curing agent" and "the polymer binder has a hydroxyl group on the side chain, and the curing agent has an isocyanate group"; if "the curing agent has at least two hydroxyl groups, and the polymer binder has an isocyanate group on the side chain", in order to achieve full contact and adhesion between the polymer binder and the other components in the positive electrode slurry, when the polymer binder is first mixed with the other components in the positive electrode slurry, the isocyanate group in the polymer binder will also undergo a cross-linking reaction with the hydroxyl groups on the other components in the positive electrode slurry, resulting in a curing tendency of the system, which is not conducive to the coating of the prepared positive electrode slurry on the surface of the current collector.

[0113] In some embodiments, before adding the curing agent to the first system, the first system is filtered and the liquid phase is collected, and then the curing agent is added to the resulting liquid phase. This method can remove agglomerates in the first system and help reduce the occurrence of scratches on the current collector surface caused by the positive electrode slurry coating.

[0114] Furthermore, in some embodiments, the first system is filtered through a filter screen with a mesh size of 50 to 200.

[0115] In some embodiments, the mass ratio of the polymer binder to the positive electrode active material is 1:(40-55).

[0116] As an example, the mass ratio of the polymer binder to the positive electrode active material may be any one of 1:40, 1:45, 1:48.5, 1:50, 1:52 and 1:55, or a range of any two thereof.

[0117] The positive electrode slurry prepared above can be used to prepare positive electrode sheets. Positive electrode sheets can be prepared according to conventional methods in the art. For example, the positive electrode slurry is coated on the positive electrode current collector, and the positive electrode sheet is obtained through drying, cold pressing, and other processes. The coating method can be extrusion coating, transfer coating, blade coating, spraying, and other methods. The drying method can be air heating, infrared heating, microwave heating, nano steam heating, and other methods. The drying temperature can be 50-180°C, preferably 120°C.

[0118] The positive electrode sheet can be used to prepare an electrode assembly 23, and the electrode assembly can be used to prepare a battery 100, which can be used as a power source for electrical equipment.

[0119] In the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer covering at least one surface in the thickness direction of the positive electrode current collector; wherein the positive electrode active layer includes a solidified product of the positive electrode slurry provided above; and the solidified product contains a product of a cross-linking reaction between a polymer binder and a curing agent.

[0120] The positive electrode active layer of the positive electrode plate provided in the present application contains the product of the cross-linking reaction between a curing agent and a polymer binder, which can make the positive electrode active layer of the positive electrode plate less likely to crack and the positive electrode active layer less likely to separate from the positive electrode current collector. It can also make the limiting surface density of the positive electrode active layer higher and the internal resistance of the positive electrode plate lower, which is beneficial to improving the energy density of the battery prepared using the positive electrode plate.

[0121] In some embodiments, the product has the following structural formula (Formula I):

[0122]

[0123] Among them, a, b, g and h are all greater than 0, and x, y, c, d, e, i, j and k are all greater than or equal to 0.

[0124] A, B, C, D, E, G, H, I, J and K are the main chain skeletons of the polymer.

[0125] R b and R h All contain carboxylate structures.

[0126] R c and R i All contain carboxylate groups.

[0127] R d and R j All contain amide groups.

[0128] R e and R k All contain cyano groups.

[0129] R f For the connecting base.

[0130] R a and R g Each independently selected from an alkylene group or a structure containing a carboxylate group; when x is 0 or R a When y is 0 or R g When it is an alkylene group, i>0.

[0131] In the present application, a linking group refers to a structure connecting two groups, which may be an alkyl group or an aryl group, etc., and is not limited in the present application.

[0132] The structural formula of the product is shown in Formula I, which can make the positive electrode active layer of the positive electrode plate less likely to crack and the positive electrode active layer less likely to separate from the positive electrode current collector. It can also make the limiting surface density of the positive electrode active layer higher and the internal resistance of the positive electrode plate lower, which is beneficial to improving the energy density of the battery.

[0133] In some embodiments, the product has the following structural formula (Formula II):

[0134]

[0135] Among them, a, b, g and h are all greater than 0, and x, y, c, d, e, i, j and k are all greater than or equal to 0.

[0136] R b and R h All contain carboxylate structures.

[0137] R c and R i All contain carboxylate groups.

[0138] R d and R j All contain amide groups.

[0139] R e and R k All contain cyano groups.

[0140] R f For the connecting base.

[0141] R a and R g Each independently selected from an alkylene group or a structure containing a carboxylate group; when x is 0 or R a When y is 0 or R g When it is an alkylene group, i>0.

[0142] The structural formula of the product is shown in Formula II, which can make the positive electrode active layer of the positive electrode plate less likely to crack and the positive electrode active layer less likely to separate from the positive electrode current collector, and can also make the limiting surface density of the positive electrode active layer higher and the internal resistance of the positive electrode plate lower, which is beneficial to improving the energy density of the battery; and the main chain skeleton of the product has only carbon-carbon single bonds, which can improve the electrochemical stability and antioxidant ability of the polymer binder, thereby making the polymer binder less likely to decompose during the charge and discharge process of the battery.

[0143] In some embodiments, c and i>0, and R c and R i The structural formulas are R lCompared to the case where carboxylate and hydroxyl groups coexist in the same side chain, the presence of side chains containing only alkyl and carboxylate groups in the molecular structure of the polymer binder can further improve the flexibility of the positive electrode active layer and help further reduce cracking of the positive electrode active layer.

[0144] As an example, R l is a C1-C5 alkyl group; for example, R l It is methyl, ethyl, propyl or butyl, etc.

[0145] In some embodiments, R f It is a straight-chain alkyl group; it can reduce the steric hindrance when the isocyanate group on the curing agent and the hydroxyl group on the polymer binder undergo cross-linking reaction, which is beneficial to better cross-linking reaction between the curing agent and the polymer binder, and is beneficial to further improve the cohesion of the positive electrode active layer.

[0146] As an example, R f is a C1-C8 straight chain alkyl group, such as R f For hexyl, etc.

[0147] In some embodiments, R b and R h The structural formulas are M3 is a metal cation, for example, a lithium ion or a sodium ion.

[0148] In some embodiments, R d and R j The structural formulas are R m and R n Each is independently a hydrogen atom or an alkyl group.

[0149] Furthermore, in some embodiments, R m and R n Each independently represents a hydrogen atom or a C1-C5 alkyl group; for example, R m and R n All are hydrogen atoms.

[0150] In some embodiments, R e and R k The structural formulas are R o It is a cyano group or an alkyl group substituted with a cyano group.

[0151] Furthermore, in some embodiments, R o is a cyano group or a cyano-substituted C1-C5 alkyl group; for example, R o It is a cyano group.

[0152] In some embodiments, Ra and R g The structural formulas are R p is an alkylene group, and R a and R g The carboxylate group in is connected to the main chain of the product. As an example, R p is a C1-C5 alkylene group; for example, R p It is methylene, ethylene, propylene or butylene, etc.

[0153] In some embodiments, both d and j are greater than 0, which is beneficial for further reducing the cracking of the positive electrode active layer and the separation of the positive electrode active layer from the current collector.

[0154] In some embodiments, both e and k are greater than 0, which is beneficial for further reducing the cracking of the positive electrode active layer and the separation of the positive electrode active layer from the current collector.

[0155] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer covering at least one surface of the negative electrode current collector in the thickness direction. This application does not specifically limit the thickness of the negative electrode current collector and the negative electrode active layer, as long as they can achieve the objectives of this application. For example, the thickness of the negative electrode current collector is 4 μm to 12 μm, and the thickness of the negative electrode active layer on a single surface of the negative electrode current collector is 30 μm to 130 μm.

[0156] The material of the negative electrode current collector may include aluminum foil, copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam or a polymer substrate covered with a conductive metal, etc.; wherein the conductive metal includes but is not limited to copper, nickel or titanium, and the material of the polymer substrate includes but is not limited to at least one of polyethylene, polypropylene, ethylene propylene copolymer, polyethylene terephthalate, polyethylene naphthalate and poly(p-phenylene terephthalamide).

[0157] The negative electrode active material in the negative electrode active layer includes graphite, coke, etc., or the negative electrode active material in the negative electrode active layer includes lithium alone, an alloy formed by lithium and other metal elements or non-metal elements, wherein the metal elements include tin (Sn), zinc (Zn), aluminum (Al), magnesium (Mg), silver (Ag), gold (Au), gallium (Ga), indium (In), foil (Pt), etc., and the non-metal elements include boron (B), carbon (C), silicon (Si), etc.

[0158] The conductive agent in the negative electrode active layer may include but is not limited to carbon materials, metals or conductive polymers, etc. The carbon material may include at least one of conductive carbon black (Super P), superconducting carbon black, carbon nanotubes (CNTs), carbon nanofibers, acetylene black, Ketjen black, natural graphite, artificial graphite, flake graphite, carbon dots or graphene, etc. The metal may include metal powder or metal fiber of copper, iron, aluminum, etc. The conductive polymer may include at least one of polythiophene, polypyrrole, polyaniline, polyphenylene and polyphenylene ethylene.

[0159] The binder in the negative electrode active layer can be selected from the adhesive composition provided above for preparing the electrode, and the binder can also include but is not limited to polypropylene alcohol, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyamide-imide, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl pyrrolidone, polyethylene, polypropylene, epoxy resin, nylon, styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral, water-based acrylic resin, carboxymethyl cellulose (CMC) or sodium carboxymethyl cellulose (CMC-Na) and the like. At least one of the following.

[0160] As an example, when the adhesive of the negative electrode plate is the adhesive composition for preparing the electrode plate provided above, the method for preparing the negative electrode plate includes: firstly mixing a system containing a polymer adhesive, a conductive agent, a negative electrode active material and a solvent to obtain a first system; and then adding a curing agent to the first system to perform a second mixing.

[0161] As an example, when other conventional adhesives are used as the binder in the negative electrode sheet, the negative electrode sheet can be prepared according to conventional methods in the art. For example, the negative electrode active material, conductive agent, and binder described above are dispersed in a solvent, which can be N-methylpyrrolidone (NMP) or deionized water, to form a uniform negative electrode slurry. The negative electrode slurry is then coated on the negative electrode current collector, and the negative electrode sheet is obtained through processes such as drying and cold pressing. The coating method can be extrusion coating, transfer coating, blade coating, spraying, etc. The drying method can be air heating, infrared heating, microwave heating, nano steam heating, etc. The drying temperature can be 50 to 180°C, preferably 120°C.

[0162] Next, one or more embodiments will be described in more detail with reference to the following examples. Of course, these examples do not limit the scope of one or more embodiments.

[0163] Example 1

[0164] (1) Preparation of polymer adhesive:

[0165] 400 mL of deionized water was added to a 1000 mL three-necked flask, and then the comonomer was added to the three-necked flask. Then, potassium persulfate initiator was added, and the mixture was stirred under condensation reflux at 60° C. for 6 hours to obtain an initial polymer system; then, a 10 wt % sodium hydroxide aqueous solution was used to adjust the pH of the initial polymer system to 7.0, and after dialysis in a 2.5W molecular weight dialysis bag, the mixture was centrifuged and dried to obtain a polymer adhesive.

[0166] The comonomers are sodium acrylate, acrylamide, butyl acrylate and hydroxyethyl acrylate in a molar ratio of 3:2:3:2; the molar amount of potassium persulfate initiator is 0.25% of the total molar amount of the comonomers.

[0167] (2) Preparation of positive electrode slurry:

[0168] Lithium iron phosphate, Super P, and the polymer binder prepared in step (1) were added to a stirring tank, followed by deionized water, and stirred at 1000 rpm for 2.5 hours to obtain a first system. The obtained first system was filtered through a 150-mesh filter, and the liquid phase was collected. Hexamethylene diisocyanate was added to the obtained liquid phase, and stirred at 400 rpm for 2 minutes to obtain a positive electrode slurry; wherein the mass ratio of lithium iron phosphate, Super P, polymer binder, deionized water, and hexamethylene diisocyanate was 97:1:2:60:0.5.

[0169] (3) Preparation of positive electrode sheet:

[0170] The positive electrode slurry prepared in step (2) is immediately and evenly coated on one surface of the positive electrode collector aluminum foil (thickness of 15 μm) and dried and cured in a blower at 120°C for 5 minutes. Then, the newly prepared positive electrode slurry is immediately and evenly coated on the other surface of the positive electrode collector aluminum foil, and then cold pressed, trimmed, and cut into pieces. It is dried under vacuum conditions at 120°C for 4 hours to obtain a positive electrode sheet; wherein the thickness of the single-sided positive electrode active material layer is 100 μm.

[0171] Example 2

[0172] The difference between Example 2 and Example 1 is that the mass ratio of lithium iron phosphate, Super P, polymer adhesive, deionized water and hexamethylene diisocyanate is 97:1:2:60:0.1.

[0173] Example 3

[0174] The difference between Example 3 and Example 1 is that the mass ratio of lithium iron phosphate, Super P, polymer adhesive, deionized water and hexamethylene diisocyanate is 97:1:2:60:0.3.

[0175] Example 4

[0176] The difference between Example 4 and Example 1 is that the mass ratio of lithium iron phosphate, Super P, polymer adhesive, deionized water and hexamethylene diisocyanate is 97:1:2:60:0.8.

[0177] Example 5

[0178] The difference between Example 5 and Example 1 is that the mass ratio of lithium iron phosphate, Super P, polymer adhesive, deionized water and hexamethylene diisocyanate is 97:1:2:60:1.

[0179] Example 6

[0180] The difference between Example 6 and Example 1 is that the hexamethylene diisocyanate in Example 1 is replaced by polyisocyanate.

[0181] Example 7

[0182] The difference between Example 7 and Example 1 is that the comonomers used are sodium acrylate, butyl acrylate, and hydroxypropyl acrylate in a molar ratio of 5:3:2.

[0183] Example 8

[0184] The difference between Example 8 and Example 1 is that the comonomers used are sodium lithium acrylate, acrylonitrile, acrylamide, and hydroxyethyl acrylate in a molar ratio of 3:3:2:2.

[0185] Example 9

[0186] The difference between Example 9 and Example 1 is that the comonomers used are sodium acrylate, butyl acrylate, and hydroxyethyl acrylate in a molar ratio of 5:3:2.

[0187] Example 10

[0188] The difference between Example 10 and Example 1 is that the comonomers used are sodium acrylate and hydroxyethyl acrylate in a molar ratio of 8:2.

[0189] Example 11

[0190] The difference between Example 11 and Example 1 is that the comonomers used are sodium acrylate, acrylonitrile, butyl acrylate, and hydroxyethyl acrylate in a molar ratio of 3:2:3:2.

[0191] Comparative Example 1

[0192] Comparative Example 1 differs from Example 1 in that hexamethylene diisocyanate is not used in step (2); step (2) of Comparative Example 1 is as follows: lithium iron phosphate, Super P, and the polymer binder prepared in step (1) are added to a stirring tank, followed by deionized water, and stirred at 1000 rpm for 2.5 hours to obtain a first system. The obtained first system is filtered through a 150-mesh filter, and the liquid phase is collected to obtain a positive electrode slurry; wherein the mass ratio of lithium iron phosphate, Super P, polymer binder, and deionized water is 97:1:2:60.

[0193] Comparative Example 2

[0194] The difference between Comparative Example 2 and Example 1 is that the polymer binder in the positive electrode slurry is styrene-butadiene rubber.

[0195] Comparative Example 3

[0196] The difference between Comparative Example 3 and Comparative Example 1 is that the polymer binder in the positive electrode slurry is styrene-butadiene rubber.

[0197] Table 1 Preparation parameters of polymer binders and positive electrode slurries of Examples 1 to 11 and Comparative Examples 1 to 3

[0198]

[0199]

[0200] In Table 1, “ / ” means that there is no corresponding parameter.

[0201] Detect the performance of the positive electrode:

[0202] (1) Adhesion test between the positive electrode active layer and the positive electrode current collector aluminum foil in the positive electrode sheet

[0203] The positive electrode slurry prepared in Examples 1 to 11 and Comparative Examples 1 to 3 was immediately and evenly coated on one surface of the positive electrode current collector aluminum foil (thickness 15 μm) and dried and cured in a blower at 120°C for 5 minutes, and then cold pressed, trimmed, and cut into pieces. It was then dried under vacuum conditions at 120°C for 4 hours to obtain the positive electrode sheet to be tested; wherein the thickness of the positive electrode active material layer was 100 μm.

[0204] Take the positive electrode sheet to be tested and use a blade to cut a positive electrode sheet sample with a width of 30mm and a length of 140mm. Attach the special double-sided tape NITTO.NO5000NS to the steel plate. The double-sided tape is 20mm wide and 120mm long. Attach the fixed-size positive electrode sheet sample cut above to the double-sided tape, with the positive active layer of the positive electrode sheet sample facing the double-sided tape and adhered to the double-sided tape. Then use a 3kg pressure roller to roll the surface of the positive electrode sheet sample three times in the same direction to obtain the sample to be tested. The sample to be tested was placed between the upper and lower clamps of a testing machine (Instron 3343) so that the direction of the steel plate pointing to the positive electrode sheet sample (i.e., the thickness direction of the positive electrode active layer) was parallel to the horizontal direction. The end of the steel plate not attached to the positive electrode sheet sample was fixed with the lower clamp, and the positive electrode current collector aluminum foil was fixed with the upper clamp. The upper clamp of the testing machine applied a peeling force at a peeling speed of 10 mm / min. When the upper clamp moved 50 mm, the peeling force F (in N) was recorded. The bonding force between the positive electrode active layer and the positive electrode current collector aluminum foil is f1, f1 = F / L, where f1 is in N / m and L is the width of the double-sided tape.

[0205] (2) Cohesion test of the positive electrode active layer in the positive electrode sheet

[0206] The positive electrode slurry prepared in Examples 1 to 11 and Comparative Examples 1 to 3 was immediately and evenly coated on one surface of the positive electrode current collector aluminum foil (thickness 15 μm) and dried and cured in a blower at 120°C for 5 minutes, and then cold pressed, trimmed, and cut into pieces. It was then dried under vacuum conditions at 120°C for 4 hours to obtain the positive electrode sheet to be tested; wherein the thickness of the positive electrode active material layer was 100 μm.

[0207] Take the positive electrode sheet to be tested, and use a blade to cut a positive electrode sheet sample with a width of 30mm and a length of 130mm. Stick the special double-sided tape NITTO.NO5000NS on the steel plate, the width of the double-sided tape is 20mm, and the length of the double-sided tape is 130mm. Stick the fixed-size positive electrode sheet sample cut above on the double-sided tape, with the side of the positive electrode current collector aluminum foil in the positive electrode sheet sample facing away from the positive electrode active layer facing the double-sided tape and bonded to the double-sided tape. Stick the low-viscosity green tape MD-XTG-620-2335L with a width of 20mm and a length of 270mm flatly on the surface of the positive electrode active layer in the positive electrode sheet sample and fix the opposite ends of the paper bag with wrinkle glue. Then use a pressure roller weighing 3kg to roll along the surface of the positive electrode sheet sample in the same direction three times to obtain the sample to be tested. The sample to be tested was then placed between the upper and lower clamps of a testing machine (Instron 3343) so that the direction pointing to the positive electrode sample (i.e., the thickness direction of the positive electrode active layer) was parallel to the horizontal direction. The end of the steel plate not attached to the positive electrode sample was fixed with the lower clamp. The low-viscosity green tape was folded upward and fixed with the upper clamp. The upper clamp of the testing machine applied a peel force at a peel speed of 10 mm / min. When the upper clamp moved 50 mm, the peel force F (in N) at this point was recorded. The cohesive force of the positive electrode active layer was f2, f2 = F / L, where f2 is in N / m and L is the width of the low-viscosity green tape.

[0208] (3) Limiting surface density test of the positive electrode active layer in the positive electrode sheet

[0209] The positive electrode slurries prepared in Examples 1 to 11 and Comparative Examples 1 to 3 were immediately and evenly coated (referred to as the first coating) on ​​one surface of a positive electrode current collector aluminum foil (thickness of 15 μm) and dried in an oven at 80°C for 10 min (referred to as the first drying). The density of the positive electrode active layer after the first drying was 150 g / m 2 .

[0210] After the first drying, observe the positive electrode sheet. If there is no cracking on the surface of the active layer of the positive electrode sheet and the positive electrode active layer has not fallen off, perform a second coating and a second drying on the surface of the positive electrode active layer. The second coating and second drying operations are the same as the first coating and first drying. The density of the positive electrode active layer after each drying is controlled to be 10g / m higher than the density of the positive electrode active layer after the previous drying. 2 .

[0211] Repeat the above operation. When cracks appear on the surface of the positive electrode active layer of the positive electrode sheet after a certain drying, the density of the positive electrode active layer after the previous drying is recorded as the limiting surface density.

[0212] (4) Folding test of the positive electrode active layer in the positive electrode sheet

[0213] The positive electrode sheets prepared in Examples 1-11 and Comparative Examples 1-3 were folded in half and rolled three times in the same direction using a 2 kg roller. The positive electrode sheets were then flattened and the above process repeated until light leakage from the folded portion of the sheet ceased. The number of folds was recorded. Each group was tested five times and the average value was calculated.

[0214] (5) Resistance test of positive electrode

[0215] Use the CRM-01 electrode resistance tester to test the resistance of the positive electrode. Test each group 5 times and take the average value.

[0216] Among them, the performance of the positive electrode is shown in Table 2:

[0217] Table 2 Performance of positive electrode sheet

[0218]

[0219] The polymer adhesive prepared in Example 1 was characterized by infrared spectroscopy. Figure 6 shown; from Figure 6 It can be seen that the wave number is 1662cm -1 The peak and wave number at 1320 cm -1 The peaks at 1662 cm-1 correspond to the -C=O- and -CO- bonds of the carboxyl anion in the polymer adhesive. -1 The peak and wave number at 1330 cm -1 The peaks at 1662 cm-1 correspond to the -C=O- and -CO- bonds of the carboxylate groups in the polymer adhesive. -1 The peak and wave number at 1560 cm -1 The peaks at 1662 cm-1 correspond to the -C=O- and -CN- bonds of the amide groups in the polymer adhesive. -1 The peak at wave number is 3300 cm -1 The peak at wave number is 1330 cm -1 The peaks at correspond to the -C=O- bond, hydroxyl group and -CO- bond in the hydroxy ester in the polymer adhesive, respectively; this indicates that a copolymerization reaction occurred between the comonomers sodium acrylate, acrylamide, butyl acrylate and hydroxyethyl acrylate in Example 1 to form a copolymer.

[0220] The polymer adhesive prepared in Example 1 was added to a stirring tank, and then deionized water was added and stirred at 1000 rpm for 2.5 hours to obtain a first system. Hexamethylene diisocyanate was added to the first system and stirred at 400 rpm for 2 minutes. The system was dried to obtain a cross-linked product. The cross-linked product after the cross-linking reaction between the polymer adhesive prepared in Example 1 and the curing agent was characterized by infrared spectroscopy. The results are as follows: Figure 7 shown; from Figure 6 and Figure 7 It can be seen from the comparison that compared with Figure 6 , Figure 7 The medium wave number is 3300cm -1 The peak corresponding to the hydroxyl group in the hydroxy ester almost disappeared, indicating that the hydroxyl group in the polymer adhesive had reacted; and the wave numbers of the peaks corresponding to the -C=O- bond and the -CN- bond formed after the hydroxyl group reacted with the carboxylate group were 1662 cm -1 and 1560cm -1 (coinciding with the -C=O- bond and -CN- bond of the amide group in the polymer adhesive), which is consistent with expectations; indicating that a cross-linking reaction occurs between the hydroxyl group in the polymer adhesive and the isocyanate group in the curing agent (i.e., hexamethylene diisocyanate).

[0221] As can be seen from Table 2, compared with Comparative Examples 1 to 3, the positive electrode sheets prepared using the polymer binders and curing agents of Examples 1 to 11 have higher cohesive force of the positive electrode active layer, higher adhesion between the positive electrode active layer and the positive electrode current collector, higher limiting surface density of the positive electrode active layer, generally more times that the positive electrode sheet can be folded, and lower internal resistance of the positive electrode sheet.

[0222] It can be seen from Examples 1 to 5 that the ratio of polymer binder to curing agent can further affect the relevant performance of the positive electrode sheet; the more curing agent is used, the higher the cohesion of the positive electrode active layer, the higher the adhesion between the positive electrode active layer and the positive electrode current collector, and the higher the limiting surface density of the positive electrode active layer; the more polymer binder is used, the more times the positive electrode sheet can be folded, the higher the flexibility of the positive electrode sheet, and the less likely the positive electrode active layer is to crack.

[0223] It can be seen from Example 1 and Example 6 that the use of hexamethylene diisocyanate or polyisocyanate as the curing agent can make the positive electrode active layer of the prepared positive electrode sheet have higher cohesive force, higher adhesion between the positive electrode active layer and the positive electrode current collector, higher limiting surface density of the positive electrode active layer, generally more times that the positive electrode sheet can be folded, and lower internal resistance of the positive electrode sheet.

[0224] It can be seen from Examples 1, 7 and 9 that replacing the amide group in the polymer binder (i.e., Example 1) with a carboxylate (i.e., sodium carboxylate) structure (i.e., Example 7 and Example 9) will lead to an increase in the cohesive force of the positive electrode active layer and an increase in the adhesion between the positive electrode active layer and the current collector; indicating that: compared with the amide group in the polymer binder, the carboxylate structure in the polymer binder is beneficial to further improve the cohesive force of the positive electrode active layer and the adhesion between the positive electrode active layer and the positive electrode current collector.

[0225] It can be seen from Example 1 and Example 8 that replacing the carboxylate group in the polymer binder (i.e., Example 1) with a cyano group (i.e., Example 8) will lead to an increase in the cohesive force of the positive electrode active layer and the adhesion between the positive electrode active layer and the current collector, but will lead to a decrease in the number of times the positive electrode sheet can be folded; this shows that: compared with the carboxylate group in the polymer binder, the cyano group in the polymer binder is beneficial to further improve the cohesive force of the positive electrode active layer and the adhesion between the positive electrode active layer and the current collector; this shows that: compared with the cyano group in the polymer binder, the carboxylate group in the polymer binder is beneficial to increase the number of times the positive electrode sheet can be folded.

[0226] It can be seen from Example 1 and Example 10 that replacing the amide group and carboxylate group in the polymer binder (i.e., Example 1) with a carboxylate (i.e., sodium carboxylate) structure (i.e., Example 10) will lead to an increase in the cohesive force of the positive electrode active layer and the adhesion between the positive electrode active layer and the positive electrode current collector, but will lead to a decrease in the number of times the positive electrode sheet can be folded; this shows that: compared with the amide group and carboxylate group in the polymer binder, the carboxylate structure in the polymer binder is beneficial to further improve the cohesive force of the positive electrode active layer and the adhesion between the positive electrode active layer and the positive electrode current collector.

[0227] It can be seen from Examples 1 and 11 that replacing the amide group in the polymer binder (i.e., Example 1) with a cyano group (i.e., Example 11) will lead to an increase in the cohesive force of the positive electrode active layer and an increase in the adhesion between the positive electrode active layer and the current collector; this indicates that compared with the amide group in the polymer binder, the cyano group in the polymer binder is beneficial to further improve the cohesive force of the positive electrode active layer and the adhesion between the positive electrode active layer and the current collector.

[0228] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. An adhesive composition for preparing a pole piece, characterized in that: including a polymer binder and a curing agent; The molecular structure of the polymer adhesive includes a first structural unit and a second structural unit; the side chain of the first structural unit has a hydroxyl group, the side chain of the second structural unit has a carboxylate structure, and the side chain of the molecular structure of the polymer adhesive has a carboxylate group; The curing agent has at least two isocyanate groups in its molecular structure.

2. The adhesive composition for preparing a pole piece according to claim 1, characterized in that: The molecular structure of the polymer adhesive further includes a third structural unit, and the side chain of the third structural unit only has an alkyl group and a carboxylate group.

3. The adhesive composition for preparing a pole piece according to claim 1 or 2, characterized in that: The side chain in the molecular structure of the polymer adhesive has a cyano group and / or an amide group.

4. The adhesive composition for preparing a pole piece according to any one of claims 1 to 3, characterized in that: The main chain in the molecular structure of the polymer binder has only carbon-carbon single bonds.

5. The adhesive composition for preparing a pole piece according to claim 1, characterized in that: The molecular structure of the polymer adhesive includes the first structural unit and the second structural unit; the structural formula of the first structural unit is as follows: R1 is an alkyl group substituted with a hydroxyl group; the structural formula of the second structural unit is as follows: M1 is a metal cation; Alternatively, the molecular structure of the polymer adhesive includes the first structural unit, the second structural unit and the third structural unit; the structural formula of the first structural unit is: R2 is a hydroxyl group or a hydroxyl-substituted alkyl group, and R3 is a hydroxyl-substituted alkyl group; the structural formula of the second structural unit is as follows: M2 is a metal cation; the structural formula of the third structural unit is as follows: R4 is an alkyl group.

6. The adhesive composition for preparing a pole piece according to claim 5, characterized in that: The molecular structure of the polymer adhesive further includes at least one of the fourth structural unit and the fifth structural unit; Wherein, the structural formula of the fourth structural unit is as follows: R5 and R6 are each independently a hydrogen atom or an alkyl group; The structural formula of the fifth structural unit is as follows: R7 is cyano or cyano-substituted alkyl.

7. The adhesive composition for preparing a pole piece according to claim 5 or 6, characterized in that: The polymer adhesive includes at least one of poly(sodium acrylate-acrylamide-butyl acrylate-hydroxyethyl acrylate), poly(sodium acrylate-butyl acrylate-hydroxypropyl acrylate), poly(lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate), poly(sodium acrylate-butyl acrylate-hydroxyethyl acrylate) and poly(sodium acrylate-hydroxyethyl acrylate).

8. The adhesive composition for preparing a pole piece according to any one of claims 1 to 7, characterized in that: The end of the side chain of the first structural unit has a hydroxyl group, and the opposite ends of the molecular structure of the curing agent respectively have an isocyanate group.

9. The adhesive composition for preparing a pole piece according to any one of claims 1 to 8, characterized in that: The curing agent includes at least one of hexamethylene diisocyanate and polyisocyanate.

10. The adhesive composition for preparing a pole piece according to any one of claims 1 to 9, characterized in that: The mass ratio of the polymer adhesive to the curing agent is (1-30):

1.

11. A method for preparing a positive electrode slurry, characterized in that: The method for preparing the positive electrode slurry adopts the adhesive composition for preparing the electrode sheet according to any one of claims 1 to 10; The preparation method of the positive electrode slurry comprises: firstly performing a first mixing on a system containing the polymer binder, the conductive agent, the positive electrode active material and water to obtain a first system; and then adding the curing agent to the first system to perform a second mixing.

12. The method for preparing the positive electrode slurry according to claim 11, wherein: The mass ratio of the polymer binder to the positive electrode active material is 1:(40-55).

13. A positive electrode slurry, characterized in that: The positive electrode slurry is prepared by the positive electrode slurry preparation method according to claim 11 or 12.

14. A positive electrode plate, characterized in that: The positive electrode sheet includes a positive electrode current collector and a positive electrode active layer covering at least one surface in the thickness direction of the positive electrode current collector; The positive electrode active layer comprises a solidified product of the positive electrode slurry according to claim 13; the solidified product contains a product of a cross-linking reaction between the polymer binder and the curing agent.

15. The positive electrode sheet according to claim 14, characterized in that: The structural formula of the product is as follows: Where a, b, g, and h are all greater than 0, and x, y, c, d, e, i, j, and k are all greater than or equal to 0; A, B, C, D, E, G, H, I, J and K are the main chain skeletons of the polymer; R b and R h All contain carboxylate structures; R c and R i All contain carboxylate groups; R d and R j All contain amide groups; R e and R k All contain cyano groups; R f is a linker; R a and R g Each independently selected from an alkylene group or a structure containing a carboxylate group; when x is 0 or R a When y is 0 or R g When it is an alkylene group, i>0.

16. The positive electrode sheet according to claim 15, characterized in that: The structural formula of the product is as follows: Where a, b, g, and h are all greater than 0, and x, y, c, d, e, i, j, and k are all greater than or equal to 0; R b and R h All contain carboxylate structures; R c and R i All contain carboxylate groups; R d and R j All contain amide groups; R e and R k All contain cyano groups; R f is a linking group; R a and R g Each independently selected from an alkylene group or a structure containing a carboxylate group; when x is 0 or R a When y is 0 or R g When it is an alkylene group, i>0.

17. The positive electrode sheet according to claim 15 or 16, characterized in that: c and i>0, and R c and R i The structural formulas are R l is an alkyl group; or / and, R f is a straight-chain alkyl group; or / and, R b and R h The structural formulas are M3 is a metal cation; or / and, R d and R j The structural formulas are R m and R n are each independently a hydrogen atom or an alkyl group; or / and, R e and R k The structural formulas are R o is cyano or cyano-substituted alkyl; or / and, R a and R g The structural formulas are R p is an alkylene group, and R a and R g The carboxylate group in is connected to the main chain of the product; or / and, d and j are both > 0; Or / and, e and k are both > 0.

18. A battery, characterized in that: The battery comprises the positive electrode sheet according to any one of claims 14 to 17.

19. An electrical device, characterized in that: The electric device comprises the battery according to claim 18.

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