Positive electrode slurry, preparation method, positive electrode plate, secondary battery and electric device

Abstract

The invention provides positive electrode slurry, a preparation method, a positive electrode plate, a secondary battery and an electric device. The positive electrode slurry comprises a composite positive electrode material, the composite positive electrode material comprises a positive electrode material matrix and a coating layer at least partially covering the positive electrode material matrix, and the coating layer comprises a siloxane cross-linked polymer. The positive electrode slurry can improve the cycle capacity retention ratio of the battery and prolong the cycle life of the battery.

Description

Technical Field

[0001] The present application relates to the technical field of secondary batteries, and in particular to a positive electrode slurry, a preparation method, a positive electrode sheet, a secondary battery and an electrical device. Background Art

[0002] Secondary batteries have the advantages of high energy density, high operating voltage, low self-discharge rate, small size and light weight, and are widely used in the field of consumer electronics.

[0003] With the rapid development of electric vehicles and mobile electronic devices, people have higher and higher requirements for secondary cycle performance. How to improve the cycle performance of batteries is a scientific and technological problem that needs to be solved urgently in the current application field of secondary batteries. Summary of the invention

[0004] The present application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode slurry and a preparation method thereof. The positive electrode slurry of the present application can improve the cycle performance of the battery and extend the service life of the battery.

[0005] A first aspect of the present application provides a binder, comprising a composite positive electrode material, wherein the composite positive electrode material comprises a positive electrode material matrix and a coating layer at least partially covering the positive electrode material matrix, wherein the coating layer comprises a siloxane cross-linked polymer.

[0006] The siloxane cross-linked polymer is coated as a coating layer on the surface of the positive electrode material matrix to reduce the possibility of corrosion side reactions of the electrolyte on the positive electrode material, reduce the possibility of dissolution of transition metal ions and lattice oxygen on the surface of the positive electrode material under high-voltage use conditions, slow down the irreversible phase change process on the surface of the positive electrode material, improve the cycle stability of the material, improve the cycle performance of the battery, and extend the service life of the battery.

[0007] In any embodiment, the positive electrode slurry further includes a binder, and the total mass content of the binder and the siloxane cross-linked polymer is 1%-5%, based on the total mass of the solid matter of the positive electrode slurry.

[0008] Controlling the total mass content of the binder and the siloxane cross-linked polymer within an appropriate range can further improve the cycle capacity retention rate of the battery and extend the cycle life of the battery.

[0009] In any embodiment, the mass ratio of the silicone cross-linked polymer to the binder is 1-5.5.

[0010] By controlling the mass ratio of the siloxane cross-linked polymer to the binder within an appropriate range, while ensuring that the siloxane cross-linked polymer is uniformly coated on the positive electrode material matrix and improving the stability of the positive electrode material during the cycle process, it can also ensure that the pole piece has excellent bonding strength, so that the pole piece has excellent structural stability during the cycle process.

[0011] In any embodiment, the positive electrode slurry satisfies: 0.08≤A / B≤0.20,

[0012] Wherein, A is the mass content of the siloxane cross-linked polymer, based on the total mass of the solid matter of the positive electrode slurry; B is the specific surface area of ​​the positive electrode material matrix, in g / m 2 .

[0013] By controlling the mass content of the siloxane cross-linked polymer and the specific surface area of ​​the positive electrode material matrix within an appropriate range, the cycle capacity retention rate of the battery can be further improved and the cycle life of the battery can be extended.

[0014] In any embodiment, the siloxane cross-linked polymer is generated by in-situ polymerization of a compound of the structure shown in Formula I and a compound of the structure shown in Formula II on the surface of the positive electrode material matrix.

[0015]

[0016] Wherein, R1, R2, R3, R5, and R6 each independently contain C 1-5 Alkyl; R4 contains hydrogen, C 1-20 Alkyl, C 1-5 At least one of the alkoxy groups, wherein n is any integer less than or equal to 100,000.

[0017] In any embodiment, the mass ratio of the compound with the structure represented by Formula I to the compound with the structure represented by Formula II is 3:100-15:100, preferably 10:100-15:100.

[0018] The mass ratio of the compound represented by the structure of Formula I to the compound represented by the structure of Formula II is within a suitable range, so that the generated siloxane cross-linked polymer is evenly coated on the surface of the positive electrode material, thereby achieving the purpose of protecting the positive electrode material and improving the stability of the positive electrode material during the cycle. The battery has a high cycle capacity retention rate and has excellent cycle performance.

[0019] In any embodiment, the R1, R2, R3, R5, and R6 each independently comprise C 1-2 Alkyl, R4 contains hydrogen, C 1-2 Alkyl, C 1-2 At least one of the alkoxy groups.

[0020] In any embodiment, the compound of the structure represented by Formula I comprises any one of methyltrimethoxysilane, ethyltrimethoxysilane and tetramethoxysilane.

[0021] And / or, the compound of the structure represented by formula II comprises terminal hydroxyl polydimethylsiloxane or terminal hydroxyl polydiethylsiloxane.

[0022] In any embodiment, the positive electrode material matrix includes lithium cobalt oxide.

[0023] A second aspect of the present application provides a method for preparing a positive electrode slurry, comprising the following steps:

[0024] Adding the compound represented by Formula I, the compound represented by Formula II and the cathode material matrix into a solvent to obtain an initial slurry;

[0025] The compound represented by the structure of Formula I and the compound represented by the structure of Formula II are polymerized in situ on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer.

[0026]

[0027] Wherein, R1, R2, R3, R5, and R6 each independently contain C 1-5 Alkyl; R4 contains hydrogen, C 1-20 Alkyl, C 1-5 At least one of the alkoxy groups, n is any integer less than or equal to 100,000,

[0028] A conductive agent and a binder are added to the initial slurry to obtain a positive electrode slurry.

[0029] In the process of preparing the positive electrode slurry, the compound of the structure shown in formula I and the compound of the structure shown in formula II are added, and during the stirring process, the compound of the structure shown in formula I and the compound of the structure shown in formula II undergo crosslinking polymerization reaction in situ on the positive electrode material matrix, and the in-situ polymerization reaction makes the generated siloxane crosslinked polymer uniformly coated on the surface of the positive electrode material matrix, reducing the possibility of electrolyte corrosion side reactions on the positive electrode material surface, reducing the possibility of transition metal ions and lattice oxygen dissolution on the positive electrode material surface under high-voltage use conditions, slowing down the irreversible phase change process on the positive electrode material surface, improving the cycle stability of the material, improving the cycle performance of the battery, and extending the service life of the battery. At the same time, the binder and the conductive agent are added after the step of in-situ polymerization on the surface of the positive electrode material matrix to generate the siloxane crosslinked polymer, so as to avoid the situation where the binder or the conductive agent is pre-entangled on the surface of the positive electrode material matrix, affecting the in-situ polymerization of the compound of the structure shown in formula I and the compound of the structure shown in formula II on the surface of the positive electrode material matrix.

[0030] In any embodiment, the polymerization temperature of the in-situ polymerization is 10°C-40°C.

[0031] In-situ polymerization is carried out in the preparation environment of the positive electrode slurry, without the need for additional temperature control, which reduces production costs and is conducive to industrial production.

[0032] In any embodiment, the preparation method specifically comprises:

[0033] Firstly, a compound of the structure shown in Formula I is added to a solvent containing a positive electrode material matrix, and then a compound of the structure shown in Formula II is added to obtain an initial slurry.

[0034] Wherein, the compound represented by the structure of formula I and the compound represented by the structure of formula II are polymerized in situ on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer; and / or,

[0035] A conductive agent is first added to the initial slurry, and then a binder is added to obtain a positive electrode slurry.

[0036] Controlling the order of adding the compound of the structure shown in Formula I and the compound of the structure shown in Formula II is conducive to the full reaction of the two, improving the coating effect of the generated siloxane cross-linked polymer on the positive electrode material, and can further improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0037] Controlling the order of adding the conductive agent and the binder so that the composite positive electrode material is in full contact with the conductive agent and the conductivity of the electrode sheet is improved, which can further improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0038] In any embodiment, the total mass fraction of the compound of formula I, the compound of formula II and the binder is 1%-5%, based on the total mass of the compound of formula I, the compound of formula II, the positive electrode material matrix, the binder and the conductive agent.

[0039] By controlling the total mass fraction of the compound of the structure shown in Formula I, the compound of the structure shown in Formula II and the binder within an appropriate range, the cycle capacity retention rate of the battery can be further improved and the cycle life of the battery can be extended.

[0040] In any embodiment, the ratio of the total mass of the compound having the structure represented by formula I and the compound having the structure represented by formula II to the mass of the binder having the structure represented by formula II is 1-5.5.

[0041] By controlling the ratio of the total mass of the compound of the structure shown in Formula I and the compound of the structure shown in Formula II to the mass of the binder input within an appropriate range, the cycle capacity retention rate of the battery can be further improved and the cycle life of the battery can be extended.

[0042] In any embodiment, the positive electrode slurry satisfies: 0.08≤C / B≤0.20,

[0043] Wherein, C is the total mass fraction of the compound of formula I and the compound of formula II, based on the total mass of the compound of formula I, the compound of formula II, the positive electrode material matrix, the binder and the conductive agent; B is the specific surface area of ​​the positive electrode material matrix, in g / m 2 .

[0044] By controlling the total mass fraction of the compound represented by the structure of formula I and the compound represented by the structure of formula II to be within a suitable range and the specific surface area of ​​the positive electrode material matrix, the mass content of the generated siloxane cross-linked polymer and the specific surface area of ​​the positive electrode material matrix are within a suitable range, the cycle capacity retention rate of the battery can be further improved and the cycle life of the battery can be extended.

[0045] The third aspect of the present application provides a positive electrode plate, including a positive electrode collector and a positive electrode film layer arranged on at least one surface of the positive electrode collector, wherein the positive electrode film layer is prepared from the positive electrode slurry described in the first aspect or the positive electrode slurry prepared by the preparation method of the second aspect.

[0046] In any embodiment, the infrared spectrum of the positive electrode film layer has a wavelength at 1100 cm -1 Up to 1000cm -1 characteristic peaks.

[0047] The fourth aspect of the present application provides a secondary battery, comprising the positive electrode sheet described in the third aspect.

[0048] A fifth aspect of the present application provides an electrical device, comprising the secondary battery described in the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a schematic diagram of a secondary battery according to an embodiment of the present application;

[0050] Figure 2 yes Figure 1 An exploded view of a secondary battery according to an embodiment of the present application is shown;

[0051] Figure 3 is a schematic diagram of a battery module according to an embodiment of the present application;

[0052] Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0053] Figure 5 yes Figure 4An exploded view of a battery pack according to an embodiment of the present application is shown;

[0054] Figure 6 is a schematic diagram of an electrical device using a secondary battery according to an embodiment of the present application as a power source;

[0055] Figure 7 is the infrared spectra of the positive electrode film layers of Example 1 and Comparative Example 1 of the present application;

[0056] Figure 8 It is a test chart of the battery cycle capacity retention rate of Example 1 and Comparative Example 1 of the present application.

[0057] Reference numerals:

[0058] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 secondary battery; 51 shell; 52 electrode assembly; 53 cover plate. DETAILED DESCRIPTION

[0059] Below, the embodiments of the positive electrode slurry, preparation method, positive electrode sheet, secondary battery and electric device of the present application are specifically disclosed with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0060] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0061] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0062] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0063] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0064] If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0065] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0066] At present, in order to improve the cycle performance of positive electrode materials, positive electrode materials are coated to form a coating layer on the surface of the material. However, common coating layers also have limitations. For example, when linear polymers are used to coat positive electrode materials, these coating layers cannot exist stably during the cycle process and cannot improve the cycle performance of the battery.

[0067] [Cathode slurry]

[0068] Based on this, the present application provides a binder, including a composite positive electrode material, wherein the composite positive electrode material includes a positive electrode material matrix and a coating layer at least partially covering the positive electrode material matrix, wherein the coating layer contains a siloxane cross-linked polymer.

[0069] As used herein, the term "silicone cross-linked polymer" refers to an insoluble and infusible polymer composed of a network of macromolecules, which is mainly a network structure formed by linear macromolecules of silicone connected by chemical bonds.

[0070] As used herein, the term "siloxane" refers to an organosilicon polymer comprising Si-O-Si chains.

[0071] Compared with the linear structure polymer coating layer, the coating layer of the present application is a siloxane cross-linked polymer, and its coating layer structure is more complete and more stable. During the cycle of the battery, it is not easy to fall off from the surface of the positive electrode material matrix, and it remains on the surface of the positive electrode material to form a tight and uniform coating, which is beneficial to the cycle stability of the composite positive electrode material.

[0072] The siloxane cross-linked polymer is coated as a coating layer on the surface of the positive electrode material matrix to reduce the possibility of corrosion side reactions of the electrolyte on the positive electrode material, reduce the possibility of dissolution of transition metal ions and lattice oxygen on the surface of the positive electrode material under high-voltage use conditions, slow down the irreversible phase change process on the surface of the positive electrode material, improve the cycle stability of the material, improve the cycle performance of the battery, and extend the service life of the battery.

[0073] In some embodiments, the positive electrode slurry further includes a binder, and the total mass content of the binder and the siloxane cross-linked polymer is 1%-5%, based on the total mass of the solid matter of the positive electrode slurry.

[0074] In some embodiments, based on the total mass of the solid matter in the positive electrode slurry, the total mass content of the binder and the siloxane cross-linked polymer may be 1%, 2%, 3%, 4%, 5% or any value therebetween.

[0075] While protecting the positive electrode material, the siloxane cross-linked polymer can also cooperate with the binder to bond the composite positive electrode material together, enhance the electronic structure between the composite positive electrode material and the conductive agent and between the composite positive electrode active material and the current collector, and is conducive to forming a more stable electrode structure and improving the cycle performance of the battery.

[0076] The total mass content of the siloxane cross-linked polymer and the binder is controlled within a certain range. While ensuring that there are sufficient quantities of the siloxane cross-linked polymer and the binder to bond the composite positive electrode material to the conductive agent and the current collector to improve the cycle stability of the pole piece and the battery, it is also necessary to avoid excessive siloxane cross-linked polymers and binders from forming an excessively thick coating layer on the surface of the positive electrode material matrix, affecting the kinetic performance of the system. At the same time, it is also necessary to reduce the negative impact of excessive siloxane cross-linked polymers and binders on the content of the composite positive electrode material in the pole piece, and avoid excessive siloxane cross-linked polymers and binders from having a negative impact on the energy density of the battery.

[0077] In summary, controlling the total mass content of the binder and the siloxane cross-linked polymer within an appropriate range can further improve the cycle capacity retention rate of the battery and extend the cycle life of the battery.

[0078] In some embodiments, the mass ratio of the siloxane cross-linked polymer to the binder is 1-5.5.

[0079] In some embodiments, the mass ratio of the silicone cross-linked polymer to the binder may be 1, 2, 3, 4, 5, 5.5 or any value therebetween.

[0080] By controlling the mass ratio of the siloxane cross-linked polymer to the binder within an appropriate range, while ensuring that the siloxane cross-linked polymer is uniformly coated on the positive electrode material matrix and improving the stability of the positive electrode material during the cycle process, it can also ensure that the pole piece has excellent bonding force, so that the pole piece has excellent structural stability during the cycle process, thereby improving the cycle performance of the battery.

[0081] In some embodiments, the positive electrode slurry satisfies: 0.08≤A / B≤0.20,

[0082] Wherein, A is the mass content of the siloxane cross-linked polymer, based on the total mass of the solid matter of the positive electrode slurry, and B is the specific surface area of ​​the positive electrode material matrix, in g / m 2 .

[0083] In some embodiments, the value of A / B may be selected as 0.08, 0.10, 0.12, 0.14, 0.16, 0.18, 0.2, or any value therebetween.

[0084] By controlling the mass content of the siloxane cross-linked polymer and the specific surface area of ​​the positive electrode material matrix within an appropriate range, the siloxane cross-linked polymer forms a complete and uniform coating on the surface of the positive electrode material matrix, while also reducing the negative impact of an excessively thick siloxane cross-linked polymer coating on lithium ion transmission, so that the system has excellent kinetic properties, improves the battery's cycle capacity retention rate, and extends the battery's cycle life.

[0085] In some embodiments, the siloxane cross-linked polymer is generated by in-situ polymerization of a compound of the structure shown in Formula I and a compound of the structure shown in Formula II on the surface of the positive electrode material matrix.

[0086]

[0087] Wherein, R1, R2, R3, R5, and R6 each independently contain C 1-5 Alkyl; R4 contains hydrogen, C 1-20 Alkyl, C 1-5At least one of the alkoxy groups, wherein n is any integer less than or equal to 100,000.

[0088] In this article, the term “C 1-5 "Alkyl" refers to a monovalent branched or unbranched saturated hydrocarbon chain having 1, 2, 3, 4 or 5 carbon atoms. 1-5 Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl.

[0089] In some embodiments, R1, R2, R3, R5, and R6 each independently comprise C 1-2 Alkyl, R4 contains hydrogen, C 1-2 Alkyl, C 1-2 At least one of the alkoxy groups.

[0090] In this article, the term “C 1-20 "Alkyl" refers to a monovalent branched or unbranched saturated hydrocarbon chain having 1 to 20 carbon atoms.

[0091] As used herein, the term "alkoxy" refers to a group having an -O-alkyl group, ie, an alkyl group is attached to a parent core structure via an oxygen atom.

[0092] In this article, the term “C 1-5 The term "alkoxy" refers to an alkyl moiety containing 1 to 5 carbon atoms, and each occurrence thereof can be independently C1 alkoxy, C2 alkoxy, C3 alkoxy, C4 alkoxy, or C5 alkoxy.

[0093] In this article, the term “C 1-2 "Alkyl" refers to a monovalent branched or unbranched saturated hydrocarbon chain having 1 to 2 carbon atoms.

[0094] In this article, the term “C 1-2 The term "alkoxy" refers to an alkyl group containing 1 to 2 carbon atoms, and each occurrence thereof can be independently C1 alkoxy or C2 alkoxy.

[0095] In some embodiments, the compound of the structure shown in Formula I comprises

[0096] (methyltrimethoxysilane).

[0097] In some embodiments, the compound of the structure shown in Formula I comprises

[0098] (Ethyltrimethoxysilane), this compound has a high flash point and good safety.

[0099] In some embodiments, the compound of the structure shown in Formula I comprises

[0100] (Tetramethoxysilane).

[0101] In some embodiments, the compound of the structure shown in Formula I comprises

[0102] (Trimethoxysilane).

[0103] In some embodiments, the degree of polymerization n of the compound of the structure shown in Formula II can be selected as 10, 100, 500, 1000, 1500, 2000, 4000, 5000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, 90000, 100000 or any value therebetween.

[0104] In some embodiments, the compound of the structure shown in Formula II comprises

[0105] (Hydroxy-terminated polydimethylsiloxane), wherein n can be selected from 10, 100, 500, 1000, 1500, 2000, 4000, 5000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, 90000, 100000 or any value therebetween.

[0106] In some embodiments, the compound of the structure shown in Formula II comprises

[0107] (Hydroxy-terminated polydiethylsiloxane), wherein n can be selected from 10, 100, 500, 1000, 1500, 2000, 4000, 5000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, 90000, 100000 or any value therebetween.

[0108] In this context, the term "in-situ polymerization" means that the siloxane cross-linked polymer is prepared by polymerization of reactive monomers on the surface of the positive electrode material matrix.

[0109] In some embodiments, a reaction diagram of a compound of formula I and a compound of formula II undergoing polymerization to generate a siloxane cross-linked polymer is shown below:

[0110] (Note: The dotted box represents the group that reacts, and the dotted horizontal line indicates that there are still many compounds of the structure shown in formula III that continue to react)

[0111] As shown in the above formula, under the action of water in the air environment, the -OR2 group in the compound of the structure shown in formula I reacts with the terminal -OH at both ends of the compound of the structure shown in formula II, and the -OR3 groups at both ends undergo a hydrolysis reaction under the action of water in the air environment and are converted into hydroxyl groups to obtain a compound of the structure shown in formula III. Each compound of the structure shown in formula III has two hydroxyl groups and a reactive group of the -OR1 group. The compounds of the structure shown in formula III react with each other under the action of water in the air environment with the -OR1 group and the hydroxyl group to generate a network-structured siloxane cross-linked polymer.

[0112] Through in-situ polymerization, the siloxane cross-linked polymer is evenly and completely coated on the surface of the positive electrode material matrix, so as to achieve the purpose of coating and protecting the positive electrode material with the siloxane cross-linked polymer, improve the stability of the positive electrode material, and enhance the cycle performance. In addition, the siloxane cross-linked polymer generated by in-situ polymerization can effectively overcome the problem of poor solubility of the siloxane cross-linked polymer in the positive electrode slurry, and effectively avoid the processing problem that the direct addition of the siloxane cross-linked polymer leads to increased viscosity of the positive electrode slurry and difficulty in preparing the positive electrode slurry.

[0113] Compared with the preparation method in the prior art that uses an organic solution containing a polymer to treat the surface of a material and uniformly coats the polymer on the surface of the material through the action of a solvent, the in-situ polymerization preparation process of the present application is simpler, improves production efficiency, and is conducive to the industrial production of the technology.

[0114] In some embodiments, the polymerization temperature of the in-situ polymerization is 10°C to 40°C.

[0115] In some embodiments, the polymerization temperature for the in situ polymerization is 25°C.

[0116] The in-situ polymerization reaction can be carried out at room temperature, which saves resources and is also conducive to industrial production.

[0117] In some embodiments, the mass ratio of the compound of the structure shown in Formula I to the compound of the structure shown in Formula II is 3:100-15:100. In some embodiments, the mass ratio of the compound of the structure shown in Formula I to the compound of the structure shown in Formula II can be 3:100, 5:100, 7:100, 9:100, 10:100, 12:100, 14:100, 15:100 or any value therebetween.

[0118] The mass ratio of the compound represented by the structure of Formula I to the compound represented by the structure of Formula II is within a suitable range, so that the compound represented by the structure of Formula I and the compound represented by the structure of Formula II can achieve an excellent cross-linking reaction, and the generated siloxane cross-linked polymer is uniformly coated on the surface of the positive electrode material, thereby achieving the purpose of protecting the positive electrode material, improving the stability of the positive electrode material during the cycle process, and the battery has a high cycle capacity retention rate and excellent cycle performance.

[0119] In some embodiments, the mass ratio of the compound of the structure shown in Formula I to the compound of the structure shown in Formula II is 10:100-15:100. In some embodiments, the mass ratio of the compound of the structure shown in Formula I to the compound of the structure shown in Formula II can be 10:100, 11:100, 12:100, 13:100, 14:100, 15:100 or any value therebetween.

[0120] By controlling the mass ratio of the compound having the structure shown in Formula I to the compound having the structure shown in Formula II within an appropriate range, the cycle performance of the battery can be further improved.

[0121] In some embodiments, the cathode material matrix includes lithium cobalt oxide.

[0122] Lithium cobalt oxide has a high theoretical gram capacity, providing a material basis for the preparation of high energy density batteries.

[0123] In some embodiments, a method for preparing a positive electrode slurry is provided, comprising the following steps:

[0124] Adding the compound represented by Formula I, the compound represented by Formula II and the cathode material matrix into a solvent to obtain an initial slurry;

[0125] The compound represented by the structure of formula I and the compound represented by the structure of formula II are polymerized in situ on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer.

[0126]

[0127] Wherein, R1, R2, and R3 each independently contain C 1-5 Alkyl, R4 contains hydrogen, substituted or unsubstituted C 1-20 Alkyl, C 1-5 At least one of the alkoxy groups, R5 and R6 each independently contain C 1-5 Alkyl, n is any integer less than or equal to 100000;

[0128] A conductive agent and a binder are added to the initial slurry to obtain a positive electrode slurry.

[0129] In some embodiments, a reaction diagram of a compound of formula I and a compound of formula II undergoing polymerization to generate a siloxane cross-linked polymer is shown below:

[0130] (Note: The dotted box represents the group that reacts, and the dotted horizontal line indicates that there are still many compounds of the structure shown in formula III that continue to react)

[0131] As shown in the above formula, under the action of water in the air environment, the -OR2 group in the compound of the structure shown in formula I reacts with the terminal -OH at both ends of the compound of the structure shown in formula II, and the -OR3 groups at both ends undergo a hydrolysis reaction under the action of water in the air environment and are converted into hydroxyl groups to obtain a compound of the structure shown in formula III. Each compound of the structure shown in formula III has two hydroxyl groups and a reactive group of the -OR1 group. The compounds of the structure shown in formula III react with each other under the action of water in the air environment with the -OR1 group and the hydroxyl group to generate a network-structured siloxane cross-linked polymer.

[0132] Compared with the preparation method in the prior art of coating the heated and vaporized polymer and the positive electrode material under high temperature environment, the process is more complicated. The preparation method of the present application can coat the positive electrode material during the preparation of the positive electrode slurry, which greatly reduces the preparation cost, simplifies the process, and is conducive to industrial production.

[0133] Compared with the preparation method in the prior art of first pretreating the positive electrode material and then performing secondary calcination to achieve coating, the preparation method of the present application avoids the negative impact of secondary calcination on the surface structure of the material, and the absence of secondary calcination also greatly reduces costs.

[0134] In the process of preparing the positive electrode slurry, the compound of the structure shown in formula I and the compound of the structure shown in formula II are added, and during the stirring process, the compound of the structure shown in formula I and the compound of the structure shown in formula II undergo crosslinking polymerization reaction in situ on the positive electrode material matrix, and the in-situ polymerization reaction makes the generated siloxane crosslinked polymer uniformly coated on the surface of the positive electrode material matrix, reducing the possibility of electrolyte corrosion side reactions on the positive electrode material, reducing the possibility of transition metal ions and lattice oxygen dissolution on the surface of the positive electrode material under high-voltage use conditions, slowing down the irreversible phase change process on the surface of the positive electrode material, improving the cycle stability of the material, improving the cycle performance of the battery, and extending the service life of the battery. At the same time, the binder and the conductive agent are added after the step of in-situ polymerization on the surface of the positive electrode material matrix to generate the siloxane crosslinked polymer, so as to avoid the situation where the binder or the conductive agent is pre-entangled on the surface of the positive electrode material matrix, affecting the in-situ polymerization of the compound of the structure shown in formula I and the compound of the structure shown in formula II on the surface of the positive electrode material matrix.

[0135] In some embodiments, the polymerization temperature of the in-situ polymerization is 10°C-40°C.

[0136] In some embodiments, the polymerization temperature may be selected to be 10°C, 20°C, 30°C, 40°C, or any value therebetween.

[0137] In some embodiments, the polymerization temperature is 25°C.

[0138] The preparation method of the present application can be completed at ambient temperature, which greatly reduces the cost and is conducive to industrial production.

[0139] In some embodiments, the preparation method of the initial slurry is specifically as follows:

[0140] A positive electrode material matrix is ​​first added to a solvent containing a compound having a structure shown in formula I, and then a compound having a structure shown in formula II is added, and in-situ polymerization is performed on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer, to obtain an initial slurry, wherein the compound having a structure shown in formula I and the compound having a structure shown in formula II are in-situ polymerized on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer.

[0141] In some embodiments, the preparation method of the initial slurry is specifically as follows:

[0142] A compound with a structure shown in Formula II is first added to a solvent containing a compound with a structure shown in Formula I, and then a positive electrode material matrix is ​​added to obtain an initial slurry, wherein the compound with a structure shown in Formula I and the compound with a structure shown in Formula II are in situ polymerized on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer.

[0143] In some embodiments, the preparation method of the initial slurry is specifically as follows:

[0144] A compound having a structure represented by formula II is first added to a solvent containing a positive electrode material matrix, and then a compound having a structure represented by formula I is added to obtain an initial slurry, wherein the compound having a structure represented by formula I and the compound having a structure represented by formula II are in situ polymerized on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer.

[0145] In some embodiments, the preparation method of the initial slurry is specifically as follows:

[0146] A positive electrode material matrix is ​​first added to a solvent containing a compound having a structure shown in formula II, and then a compound having a structure shown in formula I is added to obtain an initial slurry, wherein the compound having a structure shown in formula I and the compound having a structure shown in formula II are in situ polymerized on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer.

[0147] In some embodiments, the preparation method of the initial slurry is specifically as follows:

[0148] A compound of structure represented by formula I is first added to a solvent containing a compound of structure represented by formula II, and then a positive electrode material matrix is ​​added to obtain an initial slurry, wherein the compound of structure represented by formula I and the compound of structure represented by formula II are in situ polymerized on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer.

[0149] In some embodiments, the preparation method specifically comprises:

[0150] A compound having a structure represented by formula I is first added to a solvent containing a positive electrode material matrix, and then a compound having a structure represented by formula II is added to obtain an initial slurry, wherein the compound having a structure represented by formula I and the compound having a structure represented by formula II are in situ polymerized on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer.

[0151] Controlling the order of adding the compound of the structure shown in Formula I and the compound of the structure shown in Formula II is conducive to the full reaction of the two, improving the coating effect of the generated siloxane cross-linked polymer on the positive electrode material, and can further improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0152] In some embodiments, a binder is first added to the initial slurry, and then a conductive agent is added to obtain a positive electrode slurry.

[0153] In some embodiments, a conductive agent is first added to the initial slurry, and then a binder is added to obtain a positive electrode slurry.

[0154] Controlling the order of adding the conductive agent and the binder so that the composite positive electrode material is in full contact with the conductive agent and the conductivity of the electrode sheet is improved, which can further improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0155] In some embodiments, the total mass fraction of the compound of formula I, the compound of formula II and the binder is 1%-5%, based on the total mass of the compound of formula I, the compound of formula II, the positive electrode material matrix, the binder and the conductive agent.

[0156] In some embodiments, based on the total mass of the compound of formula I, the compound of formula II, the positive electrode material matrix, the binder and the conductive agent, the total mass fraction of the compound of formula I, the compound of formula II and the binder can be selected to be 1%, 2%, 3%, 4%, 5% or any value therebetween.

[0157] By controlling the total mass fraction of the compound of the structure shown in Formula I, the compound of the structure shown in Formula II and the binder within an appropriate range, the cycle capacity retention rate of the battery can be further improved and the cycle life of the battery can be extended.

[0158] In some embodiments, the ratio of the total mass of the compound having the structure represented by Formula I and the compound having the structure represented by Formula II to the mass of the binder input is 1-5.5.

[0159] In some embodiments, the ratio of the total mass of the compound of formula I and the compound of formula II to the mass of the binder can be 1, 2, 3, 4, 5, 5.5 or any value therebetween.

[0160] By controlling the ratio of the total mass of the compound of the structure shown in Formula I and the compound of the structure shown in Formula II to the mass of the binder input within an appropriate range, the cycle capacity retention rate of the battery can be further improved and the cycle life of the battery can be extended.

[0161] In some embodiments, the positive electrode slurry satisfies: 0.08≤C / B≤0.20,

[0162] Wherein, C is the total mass fraction of the compound of formula I and the compound of formula II, based on the total mass of the compound of formula I, the compound of formula II, the positive electrode material matrix, the binder and the conductive agent; B is the specific surface area of ​​the positive electrode material matrix, in g / m 2 .

[0163] In some embodiments, the value of C / B may be selected as 0.08, 0.10, 0.12, 0.14, 0.16, 0.18, 0.2, or any value therebetween.

[0164] By controlling the total mass fraction of the compound represented by the structure of formula I and the compound represented by the structure of formula II to be within a suitable range and the specific surface area of ​​the positive electrode material matrix, the mass content of the generated siloxane cross-linked polymer and the specific surface area of ​​the positive electrode material matrix are within a suitable range, the cycle capacity retention rate of the battery can be further improved and the cycle life of the battery can be extended.

[0165] In some embodiments, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0166] In some embodiments, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.

[0167] In some embodiments, the positive electrode material matrix may adopt a positive electrode material for a battery that is well known in the art. As an example, the positive electrode material matrix may include at least one of the following materials: a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds, etc. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0168] [Positive electrode]

[0169] The positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode film layer is prepared from the positive electrode slurry described in any embodiment or the positive electrode slurry prepared by the preparation method described in any embodiment.

[0170] In some embodiments, the infrared spectrum of the positive electrode film layer has a wavelength at 1100 cm -1 Up to 1000cm -1 characteristic peaks.

[0171] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0172] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0173] In some embodiments, the positive electrode sheet can be prepared by the following method: the positive electrode slurry is obtained by the above-mentioned positive electrode slurry preparation method; the positive electrode slurry is coated on the positive electrode collector, and the positive electrode sheet can be obtained after drying, cold pressing and other processes.

[0174] [Negative electrode]

[0175] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0176] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0177] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0178] In some embodiments, the negative electrode active material may adopt the negative electrode active material for the battery known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0179] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0180] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0181] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0182] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0183] [Electrolytes]

[0184] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0185] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0186] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0187] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0188] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0189] [Isolation film]

[0190] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0191] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0192] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0193] In some embodiments, the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.

[0194] In some embodiments, the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0195] [Secondary battery]

[0196] In one embodiment of the present application, a secondary battery is provided, comprising a positive electrode sheet, a separator, a negative electrode sheet and an electrolyte, wherein the binder in the active material layer of the positive electrode sheet comprises the polymer of any embodiment of the present application.

[0197] In some embodiments, the secondary battery is a lithium ion battery or a sodium ion battery. During the battery charge and discharge process, active ions are inserted and removed back and forth between the positive electrode and the negative electrode. The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0198] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0199] In some embodiments, the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.

[0200] In some embodiments, the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0201] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square or any other shape. Figure 1 The secondary battery 5 is a square structure as an example.

[0202] In some embodiments, reference Figure 2 , the outer package may include a shell 51 and a cover plate 53. Among them, the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0203] In some embodiments, secondary batteries may be assembled into a battery module. The number of secondary batteries contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0204] Figure 3 4 is an example of a battery module. Figure 3 In the battery module 4, the plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by fasteners.

[0205] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0206] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0207] Figure 4 and Figure 5 1 is a battery pack 1 as an example. Figure 4 and Figure 5 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0208] In addition, the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0209] As an electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0210] Figure 6The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the high power and high energy density requirements of the power consumption device for the secondary battery, a battery pack or a battery module can be used.

[0211] Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.

[0212] Example

[0213] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0214] 1. Preparation method

[0215] Example 1

[0216] 1) Preparation of positive electrode slurry

[0217] The specific surface area of ​​96g is 0.16g / m 2 Lithium cobalt oxide (LCO) was added to 50 ml of N-methylpyrrolidone; 0.182 g of ethyltrimethoxysilane was added and stirred at a speed of 1200 r / min for 60 min to ensure that ethyltrimethoxysilane was evenly distributed on the surface of lithium cobalt oxide; 1.818 g of terminal hydroxyl polydimethylsiloxane (PDMS) (whose degree of polymerization n was 1500) was added and stirred at a speed of 500 r / min for 15 min to allow ethyltrimethoxysilane and PDMS to undergo in-situ polymerization reaction, and the reaction temperature was 25°C to obtain a primary slurry; 1 g of carbon black conductive agent was added and stirred at a speed of 1200 r / min for 15 min to uniformly distribute the conductive agent; 1 g of polyvinylidene fluoride binder was added and stirred at a speed of 1200 r / min for 15 min to obtain a positive electrode slurry, and the temperature during the preparation of the positive electrode slurry was 25°C, wherein during the stirring of the positive electrode slurry, ethyltrimethoxysilane and terminal hydroxyl polydimethylsiloxane underwent a cross-linking reaction as shown below on the surface of lithium cobalt oxide, and the specific reaction was as follows:

[0218]

[0219] 2) Preparation of positive electrode

[0220] The positive electrode slurry is evenly coated on the positive electrode current collector, and the coating surface density is 25.3 mg / cm 2After that, it is dried, cold pressed and cut to obtain the positive electrode sheet.

[0221] 3) Preparation of negative electrode sheet

[0222] Active material artificial graphite, silicon particles, conductive agent carbon black, and binder styrene-butadiene rubber (SBR) are dissolved in solvent deionized water at a weight ratio of 72:24:1:3, and mixed evenly to prepare negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil once or multiple times, and the coating surface density is 8.6 mg / cm 2 After drying, cold pressing and cutting, the negative electrode sheet is obtained.

[0223] 4) Isolation film

[0224] A polyethylene film is used as the isolation film.

[0225] 5) Preparation of electrolyte

[0226] Ethylene carbonate and diethyl carbonate are mixed in a mass ratio of 3:7, and a certain mass of lithium hexafluorophosphate (LiPF6) is added. After fully dissolved, an electrolyte solution with a LiPF6 concentration of 1 mol / L is prepared as a standard electrolyte.

[0227] 6) Preparation of batteries

[0228] The positive electrode sheet, the separator, and the negative electrode sheet of Example 1 are stacked in order, so that the separator is between the positive and negative electrode sheets to play an isolating role, and then wound to obtain a bare cell, and the bare cell is welded with a pole ear, and the bare cell is placed in an aluminum shell, and baked at 80°C to remove water, and then the electrolyte is injected and sealed to obtain an uncharged battery. The uncharged battery is then subjected to the processes of static, hot and cold pressing, formation, shaping, and capacity testing in sequence to obtain the lithium-ion battery product of Example 1.

[0229] Embodiment 2-5

[0230] Compared with Example 1, the masses of ethyltrimethoxysilane and hydroxypolydimethylsiloxane and the mass of the binder polyvinylidene fluoride binder were adjusted. See Table 1 for specific parameters.

[0231] Embodiment 6-8

[0232] Compared with Example 1, the mass ratio of ethyltrimethoxysilane to hydroxypolydimethylsiloxane was adjusted. For specific parameters, see Table 1.

[0233] Example 9

[0234] Compared with Example 1, Example 9 adjusts the preparation method of the positive electrode slurry, which is as follows:

[0235] Add 0.182 g of ethyltrimethoxysilane to 50 ml of N-methylpyrrolidone;

[0236] Add 1.818 g of hydroxy-terminated polydimethylsiloxane (PDMS);

[0237] The specific surface area of ​​96g added is 0.16g / m 2 Lithium cobalt oxide (LCO) was prepared by stirring at a speed of 500 r / min for 15 min to allow ethyltrimethoxysilane and PDMS to undergo in-situ polymerization reaction on the surface of the lithium cobalt oxide material at a reaction temperature of 25° C. to obtain a primary slurry;

[0238] Add 1g of carbon black conductive agent and stir at 1200r / min for 15min to make the conductive agent evenly distributed;

[0239] 1 g of polyvinylidene fluoride binder was added and stirred at a speed of 1200 r / min for 15 min to obtain a positive electrode slurry. The temperature during the preparation of the positive electrode slurry was 25° C.

[0240] Example 10

[0241] Compared with Example 1, Example 10 adjusts the preparation method of the positive electrode slurry, which is as follows:

[0242] The specific surface area of ​​96g is 0.16g / m 2 Lithium cobalt oxide (LCO) was added to 50 ml of N-methylpyrrolidone;

[0243] Add 1.818 g of hydroxyl-terminated polydimethylsiloxane (PDMS) and stir at 1200 r / min for 60 min to ensure that the hydroxyl-terminated polydimethylsiloxane is evenly distributed on the surface of LCO;

[0244] 0.182 g of ethyltrimethoxysilane was added and stirred at a speed of 500 r / min for 15 min to allow ethyltrimethoxysilane and PDMS to undergo in-situ polymerization reaction on the surface of the lithium cobalt oxide material at a reaction temperature of 25° C. to obtain a primary slurry;

[0245] Add 1g of carbon black conductive agent and stir at 1200r / min for 15min to make the conductive agent evenly distributed;

[0246] 1 g of polyvinylidene fluoride binder was added and stirred at a speed of 1200 r / min for 15 min to obtain a positive electrode slurry. The temperature during the preparation of the positive electrode slurry was 25° C.

[0247] Embodiment 11

[0248] Compared with Example 1, Example 11 adjusted the preparation method of the positive electrode slurry, which is as follows:

[0249] The specific surface area of ​​96g is 0.16g / m 2 Lithium cobalt oxide (LCO) was added to 50 ml of N-methylpyrrolidone;

[0250] Add 0.182 g of ethyltrimethoxysilane and stir at 1200 r / min for 60 min to ensure that ethyltrimethoxysilane is evenly distributed on the surface of LCO;

[0251] 1.818 g of hydroxy-terminated polydimethylsiloxane (PDMS) was added and stirred at a speed of 500 r / min for 15 min to allow ethyltrimethoxysilane and PDMS to undergo in-situ polymerization reaction on the surface of the lithium cobalt oxide material at a reaction temperature of 25° C. to obtain a primary slurry;

[0252] Add 1g of polyvinylidene fluoride binder and stir at 1200r / min for 15min to make the conductive agent evenly distributed;

[0253] 1 g of carbon black conductive agent was added and stirred at a speed of 1200 r / min for 15 min to obtain positive electrode slurry. The temperature during the preparation of the positive electrode slurry was 25° C.

[0254] Comparative Examples 1-7

[0255] Compared with Example 1, the preparation method of the positive electrode slurry was adjusted, as follows:

[0256] Comparative Example 1: 96g of the specific surface area is 0.16g / m 2 Lithium cobalt oxide (LCO) was added to 50 ml of N-methylpyrrolidone;

[0257] Add 1g of carbon black conductive agent and stir at 1200r / min for 15min to make the conductive agent evenly distributed;

[0258] 3 g of polyvinylidene fluoride binder was added and stirred at a speed of 1200 r / min for 15 min to obtain a positive electrode slurry. The temperature during the preparation of the positive electrode slurry was 25° C.

[0259] Comparative Example 2: 96g of the specific surface area is 0.16g / m 2 Lithium cobalt oxide (LCO) was added to 50 ml of N-methylpyrrolidone;

[0260] Add 2 g of hydroxy-terminated polydimethylsiloxane (PDMS) and stir at 500 r / min for 15 min;

[0261] Add 1g of carbon black conductive agent and stir at 1200r / min for 15min to make the conductive agent evenly distributed;

[0262] 1 g of polyvinylidene fluoride binder was added and stirred at a speed of 1200 r / min for 15 min to obtain a positive electrode slurry. The temperature during the preparation of the positive electrode slurry was 25° C.

[0263] Comparative Example 3: 96g of the specific surface area is 0.16g / m 2 Lithium cobalt oxide (LCO) was added to 50 ml of N-methylpyrrolidone;

[0264] Add 2 g of ethyltrimethoxysilane and stir at 1200 r / min for 60 min;

[0265] Add 1g of carbon black conductive agent and stir at 1200r / min for 15min to make the conductive agent evenly distributed;

[0266] 1 g of polyvinylidene fluoride binder was added and stirred at a speed of 1200 r / min for 15 min to obtain a positive electrode slurry. The temperature during the preparation of the positive electrode slurry was 25° C.

[0267] Comparative Example 4: 96g of the specific surface area is 0.16g / m 2 Lithium cobalt oxide (LCO) was added to 50 ml of N-methylpyrrolidone to obtain an initial slurry;

[0268] Add 1g of carbon black conductive agent and stir at 1200r / min for 15min to make the conductive agent evenly distributed;

[0269] Add 1 g of polyvinylidene fluoride binder and stir at a speed of 1200 r / min for 15 min to obtain a secondary slurry;

[0270] Add 0.182 g of ethyltrimethoxysilane and stir at 1200 r / min for 60 min;

[0271] 1.818 g of hydroxy-terminated polydimethylsiloxane (PDMS) was added and stirred at a speed of 500 r / min for 15 min to obtain a positive electrode slurry. The temperature during the preparation of the positive electrode slurry was 25° C.

[0272] Comparative Example 5: 1 g of carbon black conductive agent was added to 50 ml of N-methylpyrrolidone, and stirred at 1200 r / min for 15 min to evenly distribute the conductive agent;

[0273] Add 1 g of polyvinylidene fluoride binder and stir at a speed of 1200 r / min for 15 min to obtain an initial slurry;

[0274] The specific surface area of ​​96g added is 0.16g / m 2 Lithium cobalt oxide (LCO), to obtain a secondary slurry;

[0275] Add 0.182 g of ethyltrimethoxysilane and stir at 1200 r / min for 60 min;

[0276] 1.818 g of hydroxy-terminated polydimethylsiloxane (PDMS) was added and stirred at a speed of 500 r / min for 15 min to obtain a positive electrode slurry. The temperature during the preparation of the positive electrode slurry was 25° C.

[0277] Comparative Example 6: 1 g of carbon black conductive agent was added to 50 ml of N-methylpyrrolidone, and stirred at 1200 r / min for 15 min to uniformly distribute the conductive agent;

[0278] Add 1 g of polyvinylidene fluoride binder and stir at a speed of 1200 r / min for 15 min to obtain an initial slurry;

[0279] Add 0.182 g of ethyltrimethoxysilane and stir at 1200 r / min for 60 min;

[0280] 1.818 g of hydroxy-terminated polydimethylsiloxane (PDMS) was added and stirred at a speed of 500 r / min for 15 min to obtain a secondary slurry;

[0281] The specific surface area of ​​96g added is 0.16g / m 2 Lithium cobalt oxide (LCO) is used to obtain a positive electrode slurry, and the temperature during the preparation of the positive electrode slurry is 25°C.

[0282] Comparative Example 7: 0.182 g of ethyltrimethoxysilane was added to 50 ml of N-methylpyrrolidone and stirred at a speed of 1200 r / min for 60 min;

[0283] 1.818 g of hydroxy-terminated polydimethylsiloxane (PDMS) was added and stirred at a speed of 500 r / min for 15 min at a stirring temperature of 25° C. to obtain an initial slurry;

[0284] Add 1g of carbon black conductive agent and stir at 1200r / min for 15min to make the conductive agent evenly distributed;

[0285] Add 1 g of polyvinylidene fluoride binder and stir at a speed of 1200 r / min for 15 min to obtain a secondary slurry;

[0286] The specific surface area of ​​96g added is 0.16g / m 2 Lithium cobalt oxide (LCO) is used to obtain a positive electrode slurry. The temperature during the preparation of the positive electrode slurry is 25°C.

[0287] 2. Test Method

[0288] 1. Infrared characterization of positive electrode film

[0289] Disassemble the battery, take out the positive electrode sheet, scrape the positive electrode film layer to obtain the positive electrode film layer powder, mix the positive electrode film layer powder with a solvent (such as N-methylpyrrolidone), filter after fully dissolving, take the filter residue, and use the reflection mode of the Thermo Scientific infrared spectrometer to collect the spectrum of the extracted positive electrode film layer powder. -1 ~1100cm -1 (such as 1066cm -1 If a vibration infrared peak appears near the cathode film, it can be determined that the cathode film contains Si-O functional groups.

[0290] 2. Battery cycle capacity retention rate

[0291] At 25°C and normal pressure (0.1MPa), the battery is charged at a constant current of 0.5C to a voltage of 3.5V, and then discharged at a constant current of 1C to a voltage of 3.2V. This is a charge and discharge cycle. The capacity of the first discharge is 100%, and the charge and discharge cycle is repeated 50 times. The test is stopped and the cycle capacity retention rate is recorded. The room temperature cycle capacity retention rate is used as an indicator to evaluate the room temperature cycle performance of the battery.

[0292] III. Analysis of test results of various embodiments and comparative examples

[0293] The positive electrode slurries and batteries of the embodiments and comparative examples were prepared according to the above method, and various parameters were measured. The results are shown in the table below.

[0294] Table 1

[0295]

[0296] According to the above results, the composite positive electrode material in the positive electrode slurry in Examples 1-11 includes a lithium cobalt oxide positive electrode material matrix and a siloxane cross-linked polymer at least partially covered on the positive electrode material matrix. From the comparison between Examples 1-11 and Comparative Examples 1-7, it can be seen that the surface of the positive electrode material matrix in the positive electrode slurry is coated with a siloxane cross-linked polymer, which can improve the cycle capacity retention rate of the battery and extend the cycle life of the battery.

[0297] from Figure 7 The infrared spectra of the positive electrode film layer of Example 1 and Comparative Example 1 show that the infrared spectrum of Example 1 has a peak at 1100 cm -1 Up to 1000cm -1 The characteristic peak of Si-O functional group appears, while the corresponding characteristic peak does not appear in Comparative Example 1, which proves to a certain extent that the surface of the positive electrode material matrix in the positive electrode film layer is coated with siloxane cross-linked polymer.

[0298] From the comparison between Examples 1, 2-3 and Examples 4 and 5, it can be seen that based on the total mass of the solid matter in the positive electrode slurry, the total mass content of the polyvinylidene fluoride binder and the siloxane cross-linked polymer in the positive electrode slurry is 1%-5%, which can further improve the cycle capacity retention rate of the battery and extend the cycle life of the battery.

[0299] From the comparison between Examples 1 and 3 and Examples 2, 4 and 5, it can be seen that, based on the total mass of the solid matter in the positive electrode slurry, the relationship between the mass content A of the siloxane cross-linked polymer and the specific surface area B of the lithium cobalt oxide satisfies 0.08≤A / B≤0.20, which can further improve the cycle capacity retention rate of the battery and extend the cycle life of the battery.

[0300] It can be seen from Examples 1, 6-8 that when the mass ratio of the compound ethyl trimethoxy silane of the structure shown in Formula I to the compound terminal hydroxyl polydimethylsiloxane of the structure shown in Formula II is 3:100-15:100, the battery has a high cycle capacity retention rate and excellent cycle performance. It can be seen from the comparison of Examples 1, 7 with Examples 6, 8 that when the mass ratio of the compound ethyl trimethoxy silane of the structure shown in Formula I to the compound terminal hydroxyl polydimethylsiloxane of the structure shown in Formula II is 10:100-15:100, the cycle capacity retention rate of the battery can be further improved and the cycle life of the battery can be extended.

[0301] The preparation method of the positive electrode slurry in Examples 1-11 includes the following steps: adding ethyltrimethoxysilane, a compound of the structure shown in Formula I, terminal hydroxyl polydimethylsiloxane, a compound of the structure shown in Formula II, and lithium cobalt oxide, a positive electrode material matrix, to a solvent, and in situ polymerizing ethyltrimethoxysilane and terminal hydroxyl polydimethylsiloxane on the surface of the positive electrode material matrix at 25°C to generate a siloxane cross-linked polymer to obtain an initial slurry; adding a conductive carbon black conductive agent and a polyvinylidene fluoride binder into the initial slurry, and stirring to prepare a positive electrode slurry.

[0302] From the comparison between Example 1 and Comparative Example 4, it can be seen that compared with the preparation method of Comparative Example 4: lithium cobalt oxide is put into a solvent to obtain an initial slurry; conductive carbon black conductive agent and polyvinylidene fluoride binder are sequentially put into the initial slurry to obtain a secondary slurry; ethyl trimethoxy silane of the compound of formula I and terminal hydroxyl polydimethylsiloxane of the compound of formula II are sequentially put into the secondary slurry to obtain a positive electrode slurry. The preparation method of the present application can improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0303] From the comparison between Example 1 and Comparative Example 5, it can be seen that compared with the preparation method of Comparative Example 5: the conductive carbon black conductive agent and the polyvinylidene fluoride binder are sequentially put into the solvent to obtain the initial slurry; lithium cobalt oxide is put into the initial slurry to obtain the secondary slurry; ethyl trimethoxy silane of the compound of formula I and the terminal hydroxyl polydimethylsiloxane of the compound of formula II are put into the secondary slurry to obtain the positive electrode slurry. The preparation method of the present application can improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0304] From the comparison between Example 1 and Comparative Example 6, it can be seen that compared with the preparation method of Comparative Example 6: firstly, the conductive carbon black conductive agent and the polyvinylidene fluoride binder are put into the solvent to obtain the initial slurry; the compound ethyltrimethoxysilane of the structure shown in Formula I and the compound terminal hydroxyl polydimethylsiloxane of the structure shown in Formula II are put into the initial slurry to obtain the secondary slurry; lithium cobalt oxide is put into the secondary slurry to obtain the positive electrode slurry. The preparation method of the present application can improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0305] From the comparison between Example 1 and Comparative Example 7, it can be seen that compared with the preparation method of Comparative Example 7: the compound ethyltrimethoxysilane of the structure shown in Formula I and the compound terminal hydroxyl polydimethylsiloxane of the structure shown in Formula II are sequentially put into the solvent to obtain an initial slurry; the conductive carbon black conductive agent and the polyvinylidene fluoride binder are sequentially put into the initial slurry to obtain a secondary slurry; lithium cobalt oxide is put into the secondary slurry to obtain a positive electrode slurry. The preparation method of the present application can improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0306] From the comparison between Example 1 and Example 9, it can be seen that the steps in Example 1 are: first adding ethyl trimethoxy silane, a compound of the structure shown in Formula I, to a solvent containing lithium cobalt oxide, and then adding terminal hydroxyl polydimethylsiloxane, a compound of the structure shown in Formula II, and the steps in Example 9 are: sequentially adding ethyl trimethoxy silane, a compound of the structure shown in Formula I, and terminal hydroxyl polydimethylsiloxane, a compound of the structure shown in Formula II, to the solvent, and then adding lithium cobalt oxide to the solvent. The preparation method of adding the compound of the structure shown in Formula I and the compound of the structure shown in Formula II to a solvent containing lithium cobalt oxide can further improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0307] From the comparison between Example 1 and Example 10, it can be seen that the steps in Example 1 are: first adding ethyl trimethoxy silane, a compound of the structure shown in Formula I, to a solvent containing lithium cobalt oxide, and then adding hydroxy-terminated polydimethylsiloxane, a compound of the structure shown in Formula II, and the steps in Example 10 are: first adding hydroxy-terminated polydimethylsiloxane, a compound of the structure shown in Formula II, to a solvent containing lithium cobalt oxide, and then adding ethyl trimethoxy silane, a compound of the structure shown in Formula I. The preparation method of first adding the compound of the structure shown in Formula I and then adding the compound of the structure shown in Formula II can further improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0308] From the comparison between Example 1 and Example 11, it can be seen that the steps in Example 1 are: first adding the conductive carbon black conductive agent to the initial slurry, and then adding the polyvinylidene fluoride binder, and the steps in Example 11 are: first adding the polyvinylidene fluoride binder to the initial slurry, and then adding the conductive carbon black conductive agent. The preparation method of adding the conductive agent first and then adding the binder can further improve the cycle capacity retention rate of the battery and extend the service life of the battery.

[0309] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A positive electrode slurry, characterized in that: The invention comprises a composite positive electrode material, wherein the composite positive electrode material comprises a positive electrode material matrix and a coating layer at least partially covering the positive electrode material matrix, wherein the coating layer comprises a siloxane cross-linked polymer.

2. The positive electrode slurry according to claim 1, characterized in that The positive electrode slurry further includes a binder, and the total mass content of the binder and the siloxane cross-linked polymer is 1%-5%, based on the total mass of the solid matter of the positive electrode slurry.

3. The positive electrode slurry according to claim 2, characterized in that The mass ratio of the silicone cross-linked polymer to the binder is 1-5.

5.

4. The positive electrode slurry according to any one of claims 1 to 3, characterized in that The positive electrode slurry satisfies: 0.08≤A / B≤0.20, Wherein, A is the mass content of the siloxane cross-linked polymer, based on the total mass of the solid matter of the positive electrode slurry; B is the specific surface area of ​​the positive electrode material matrix, in g / m 2 .

5. The positive electrode slurry according to any one of claims 1 to 4, characterized in that: The siloxane cross-linked polymer is generated by in-situ polymerization of a compound with a structure shown in Formula I and a compound with a structure shown in Formula II on the surface of the positive electrode material matrix. Wherein, R1, R2, R3, R5, and R6 each independently contain C 1-5 Alkyl; R4 contains hydrogen, C 1-20 Alkyl, C 1-5 At least one of the alkoxy groups, wherein n is any integer less than or equal to 100,000.

6. The positive electrode slurry according to claim 5, characterized in that The mass ratio of the compound with the structure shown in formula I to the compound with the structure shown in formula II is 3:100-15:100, and can be optionally 10:100-15:

100.

7. The positive electrode slurry according to claim 5 or 6, characterized in that: The R1, R2, R3, R5, and R6 each independently contain C 1-2 Alkyl, R4 contains hydrogen, C 1-2 Alkyl, C 1-2 At least one of the alkoxy groups.

8. The positive electrode slurry according to any one of claims 5 to 7, characterized in that: The compound represented by the structure of Formula I comprises any one of methyltrimethoxysilane, ethyltrimethoxysilane and tetramethoxysilane. And / or, the compound of the structure represented by formula II comprises terminal hydroxyl polydimethylsiloxane or terminal hydroxyl polydiethylsiloxane.

9. The positive electrode slurry according to any one of claims 1 to 8, characterized in that: The positive electrode material matrix includes lithium cobalt oxide.

10. A method for preparing a positive electrode slurry, characterized in that: The following steps are involved: Adding the compound represented by Formula I, the compound represented by Formula II and the cathode material matrix into a solvent to obtain an initial slurry; The compound represented by the structure of Formula I and the compound represented by the structure of Formula II are polymerized in situ on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer. Wherein, R1, R2, R3, R5, and R6 each independently contain C 1-5 Alkyl; R4 contains hydrogen, C 1-20 Alkyl, C 1-5 At least one of the alkoxy groups, n is any integer less than or equal to 100,000, A conductive agent and a binder are added into the initial slurry to obtain the positive electrode slurry.

11. The preparation method according to claim 10, characterized in that: The polymerization temperature of the in-situ polymerization is 10°C-40°C.

12. The preparation method according to claim 10 or 11, characterized in that: The preparation method specifically comprises: Firstly, a compound of the structure shown in Formula I is added to a solvent containing a positive electrode material matrix, and then a compound of the structure shown in Formula II is added to obtain an initial slurry. Wherein, the compound represented by the structure of formula I and the compound represented by the structure of formula II are polymerized in situ on the surface of the positive electrode material matrix to generate a siloxane cross-linked polymer; and / or, A conductive agent is first added to the initial slurry, and then a binder is added to obtain the positive electrode slurry.

13. The preparation method according to any one of claims 10 to 12, characterized in that: The total mass fraction of the compound of formula I, the compound of formula II and the binder is 1%-5%, based on the total mass of the compound of formula I, the compound of formula II, the positive electrode material matrix, the binder and the conductive agent.

14. The preparation method according to any one of claims 10 to 13, characterized in that: The ratio of the total mass of the compound with the structure shown in formula I and the compound with the structure shown in formula II to the mass of the binder is 1-5.

5.

15. The preparation method according to any one of claims 10 to 14, characterized in that: The positive electrode slurry satisfies: 0.08≤C / B≤0.20, Wherein, C is the total mass fraction of the compound of formula I and the compound of formula II, based on the total mass of the compound of formula I, the compound of formula II, the positive electrode material matrix, the binder and the conductive agent; B is the specific surface area of ​​the positive electrode material matrix, in g / m 2 .

16. A positive electrode plate, characterized in that: The invention comprises a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode film layer is prepared by the positive electrode slurry according to any one of claims 1 to 9 or the positive electrode slurry prepared by the preparation method according to any one of claims 10 to 15.

17. The positive electrode sheet according to claim 16, characterized in that: The infrared spectrum of the positive electrode film has a wavelength at 1100 cm -1 Up to 1000cm -1 characteristic peaks.

18. A secondary battery, characterized in that: Including the positive electrode sheet as described in claim 16 or 17.

19. An electrical device, characterized in that: Includes the secondary battery as claimed in claim 18.

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