Electrode assemblies, battery cells, batteries, and power consumption devices

Abstract

This application provides an electrode assembly, a battery cell, a battery, and a power-consuming device. The electrode assembly includes a negative electrode plate, a positive electrode plate, and a separator, wherein the negative electrode plate includes a negative electrode film layer, the negative electrode film layer contains a fluorine-containing polymer, and the positive electrode plate includes a positive electrode film layer, the positive electrode film layer contains a nitrile-based polymer material. The use of this electrode assembly can significantly improve the cycle performance of the battery.

Description

Cross-reference of related applications

[0001] This application claims priority to Chinese Patent Application 202310654723.2, proposed on June 5, 2023, entitled “Electrode Assembly, Battery Cell, Battery and Power Consumption Equipment,” and all contents of this application are incorporated herein by reference. [Technical Field]

[0002] This application relates to the field of lithium battery technology, and more particularly to electrode assemblies, battery cells, batteries, and power consumption devices. [Background technology]

[0003] Battery cells are widely used because they offer advantages such as reliable operating performance, no pollution, and no memory effect. For example, as environmental protection issues become increasingly important and new energy vehicles become more widespread, the demand for power battery cells tends to grow explosively.

[0004] As the range of battery applications expands, the demands on battery performance are increasing. However, since the internal resistance of battery cells causes polarization and affects the battery's cycle performance, there is a need to improve battery cycle performance. [Overview of the Initiative]

[0005] This application provides an electrode assembly, a battery cell, a battery, and a power consumption device that can effectively improve the cycle performance of the battery.

[0006] According to a first aspect, the present application provides an electrode assembly comprising a negative electrode plate, a positive electrode plate, and a separator, wherein the negative electrode plate comprises a negative electrode film layer comprising a fluorine-containing polymer, and the positive electrode plate comprises a positive electrode film layer comprising a nitrile-based polymer material.

[0007] This application demonstrates that a fluorine-containing polymer in the negative electrode film layer can form a fluoride-rich negative electrode solid electrolyte (SEI) film. This SEI film has a stable structure and can improve ionic conductivity, thereby reducing polarization and improving the battery's cycle performance. Furthermore, the nitrile-based polymer material in the positive electrode film layer can improve the ion transport performance of the positive electrode plate, while also capturing hydrogen ions and preventing their undesirable effects on the positive electrode interface. Moreover, the fluorine-containing polymer generates hydrogen ions during the SEI film construction process. Therefore, by using a nitrile-based polymer material in the positive electrode film layer, the undesirable effects of the fluorine-containing polymer on the battery's positive electrode can be effectively reduced. Both of these factors work synergistically to provide the battery containing the electrode assembly with good cycle performance.

[0008] In some embodiments, the fluorine-containing polymer includes at least one of polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, polyvinyl fluoride, fluorine-containing polyacrylate fluororubber, fluorine-containing polyester rubber, and fluorosilicone rubber. By using the above specific types of fluorine-containing polymers, batteries can be given good cycle performance.

[0009] In some embodiments, the mass percentage content of the fluorine-containing polymer in the negative electrode film layer is 0.1% to 2.5%. At this concentration, a stable SEI film with good ion transport performance can be obtained, the impact on the positive electrode is relatively small, and the battery cycle performance is better.

[0010] Preferably, the mass percentage content of the fluorine-containing polymer in the negative electrode film layer is 0.2% to 2%.

[0011] In some embodiments, the positive electrode film layer satisfies at least one of the following conditions: 1) the weight-average molecular weight of the nitrile polymer material is 200,000 to 2,000,000; 2) the mass percentage of cyano groups in the nitrile polymer material is 15% to 50%; and 3) the mass percentage content of the nitrile polymer material in the positive electrode film layer is 0.2% to 5%. In this case, the positive electrode interface has good ion transport performance and can effectively reduce the influence of hydrogen ions on the positive electrode interface, resulting in better battery cycle performance.

[0012] Preferably, the positive electrode film layer satisfies at least one of the following conditions: 1) the weight-average molecular weight of the nitrile polymer material is 400,000 to 1,000,000; 2) the mass percentage of cyano groups in the nitrile polymer material is 25% to 40%; and 3) the mass percentage content of the nitrile polymer material in the positive electrode film layer is 0.5% to 1.5%.

[0013] In some embodiments, the nitrile polymer material includes at least one of nitrile rubber, hydrogenated nitrile rubber, carboxyl nitrile rubber, polyacrylonitrile, and vulcanized nitrile rubber. Using the above specific types of nitrile polymer materials, batteries can be given better cycle performance.

[0014] In some embodiments, the positive electrode film layer further comprises a second adhesive, the second adhesive comprising at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer, sodium carboxymethylcellulose, and styrene-butadiene rubber. Further addition of the second adhesive to the positive electrode film layer, where the swelling rate of the second adhesive is relatively low, can improve the stability of the positive electrode film layer and enhance the battery's cycle performance.

[0015] In some embodiments, the positive electrode film layer contains a positive electrode active material, and the positive electrode active material is lithium iron phosphate, lithium cobaltate, Li a Ni x Co y M 1-x-y O b and includes at least one of them, where 0.8 < a < 1.2, 0 < x < 1, 0 < y < 1, 1.8 < b < 2.2, and M is selected from Mn and / or Al. The electrode assembly according to the present application has a good protective effect on the positive electrode active material, and the positive electrode interface has relatively good ion transport performance. Therefore, a positive electrode active material with a higher energy density may be used as needed.

[0016] According to a second aspect, the present application provides a method for manufacturing an electrode assembly, which includes the step of forming a negative electrode film layer on at least one side of a negative electrode current collector to obtain a negative electrode plate, where the negative electrode film layer contains a fluorine-containing polymer, and the step of forming a positive electrode film layer on at least one side of a positive electrode current collector to obtain a positive electrode plate, where the positive electrode film layer contains a nitrile-based polymer material.

[0017] According to the present application, a fluorine-containing polymer can be added to the negative electrode film layer and a nitrile-based polymer material can be added to the positive electrode film layer using a general manufacturing method. Thereby, the electrode assembly described in any one of the embodiments of the first aspect is obtained, and has any beneficial effects of the first aspect.

[0018] In some embodiments, forming a negative electrode film layer on at least one side of the negative electrode current collector specifically includes uniformly mixing a negative electrode active material with a fluorine-containing polymer, dispersing the fluorine-containing polymer on the surface of the negative electrode active material to obtain a negative electrode premix, dispersing the negative electrode premix and a first adhesive in a first solvent to obtain a negative electrode slurry, and coating the negative electrode slurry on at least one side of the negative electrode current collector to form a negative electrode film layer. First, the negative electrode active material can be premixed with the fluorine-containing polymer, and the negative electrode active material can be pre-coated on the fluorine-containing polymer, which can effectively improve the ion transport efficiency, reduce the DC impedance, realize blocking in the process of forming the SEI film, increase the toughness and structural stability of the SEI film, and improve the cycle performance of the battery.

[0019] In some embodiments, the negative electrode premix further includes a first adhesive and a first solvent. Adding the first adhesive and the first solvent to the negative electrode premix can improve the dispersion effect of the fluorine-containing polymer. Thereby, it can more easily coat the negative electrode active material and further improve the cycle performance of the battery.

[0020] In some embodiments, forming a positive electrode film layer on at least one side of the positive electrode current collector specifically includes uniformly mixing a positive electrode active material with a nitrile-based polymer material, dispersing the nitrile-based polymer material on the surface of the positive electrode active material to obtain a positive electrode premix, dispersing the positive electrode premix and a second adhesive in a second solvent to obtain a positive electrode slurry, and coating the positive electrode slurry on at least one side of the positive electrode current collector to form a positive electrode film layer. First, the positive electrode active material can be premixed with the nitrile-based polymer material, and the positive electrode active material can be pre-coated on the nitrile-based polymer material, which can effectively improve the ion transport efficiency at the positive electrode interface. Also, the nitrile-based polymer material on the surface of the positive electrode active material can capture hydrogen ions better, thereby stabilizing the metal elements on the surface of the positive electrode active material, reducing the influence of hydrogen ions on the battery performance by the fluorine-containing polymer in the negative electrode film layer, and synergistically improving the cycle performance of the battery.

[0021] In some embodiments, the positive electrode premix further contains a second solvent, and the solids content in the positive electrode premix is ​​80% to 90%. Further addition of the second solvent to the positive electrode premix can improve the dispersion effect of the nitrile polymer material. This makes it easier to coat the positive electrode active material and further improves the battery's cycle performance. Selectively, the solids content in the positive electrode premix is ​​83% to 86%.

[0022] According to a third aspect, the present application provides a battery cell comprising an electrode assembly obtained by any one embodiment of the first aspect or by a manufacturing method described in any one embodiment of the second aspect.

[0023] According to a fourth aspect, the present application provides a battery which includes a battery cell described in any one embodiment of the third aspect.

[0024] According to the fifth aspect, the present application provides a power consumption device comprising at least one of the battery cells described in any one embodiment of the third aspect or the battery described in any one embodiment of the fourth aspect.

[0025] This application provides an electrode assembly that can effectively improve the ion transport performance of a battery, reduce polarization, provide good protection for the positive electrode active material, and enable the battery to have good cycle performance. [Brief explanation of the drawing]

[0026] [Figure 1] This is a schematic diagram of a battery cell according to one embodiment of the present application. [Figure 2] Figure 1 is an exploded view of a battery cell according to one embodiment of this application. [Figure 3] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 4]This is a schematic diagram of a battery according to one embodiment of the present application. [Figure 5] Figure 4 is an exploded view of a battery according to one embodiment of this application. [Figure 6] This is a schematic diagram of a power consumption device that uses a battery cell as a power source according to one embodiment of the present application. [Modes for carrying out the invention]

[0027] The following describes in detail embodiments specifically disclosing the electrode assembly, battery cell, battery, and power consumption device of this application, with appropriate reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of well-known matters and redundant explanations of structures that are actually the same may be omitted. This is to avoid making the following explanation unnecessarily long and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and do not limit the topics described in the claims.

[0028] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the endpoints, and any combination is possible, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also predictable. Furthermore, if 1 and 2 are listed as the minimum range values ​​and 3, 4, and 5 are listed as the maximum range values, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all predictable. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means in this specification that all real numbers between "0 to 5" have already been listed, and "0 to 5" is simply a shortened representation of combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0030] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0031] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the fact that the method referred to above may further include step (c) 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 steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0032] Unless otherwise specified, the terms “includes” and “inclusion” as used in this application may be open or closed. For example, “includes” and “inclusion” may mean that other components not listed may be included or inclusion, or that only the listed components may be included or inclusion.

[0033] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the conditions A is true (or exists) and B is false (or does not exist), the condition A is false (or does not exist) but B is true (or exists), and the condition A and B are both true (or exist) all satisfy "A or B."

[0034] As described in the background technology above, as the range of battery applications expands, the demands on battery performance are also increasing. However, since the internal resistance of battery cells causes polarization and affects the battery's cycle performance, there is a need to improve the battery's cycle performance.

[0035] To address the above problem, related technologies allow for the creation of a fluoride-rich SEI film (in the case of lithium-ion batteries, the fluoride includes LiF) during the battery formation or cycling process by adding a fluorine-containing polymer to the negative electrode film layer. This controls the negative electrode / electrolyte interface of the battery, giving the SEI film a stable structure and good ionic conductivity, further reducing the DC impedance of the battery, decreasing polarization, and enabling the battery to have relatively good cycling performance.

[0036] However, the problems associated with adding fluorine-containing polymers to the negative electrode film layer are as follows: While fluorine-containing polymers are involved in the formation of the SEI film, and a good-performing SEI film can be obtained, this process involves the deposition of hydrogen ions. These hydrogen ions significantly reduce the stability of the positive electrode solid electrolyte film (CEI film) and further affect the structure of the positive electrode active material, causing the deposition of metal ions in the positive electrode active material and reducing the battery's cycle performance. This significantly weakens the positive effect of fluorine-containing polymers on improving the battery's cycle performance and limits their application.

[0037] Based on this, this application provides an electrode assembly. In this electrode assembly, a fluorine-containing polymer is added to the negative electrode film layer, and at the same time, a nitrile-based polymer material is added to the positive electrode film layer, which effectively reduces the influence of hydrogen ions on the positive electrode interface of the battery and improves the ion transport performance at the positive electrode / electrolyte interface. This works synergistically with the effect of the fluorine-containing polymer to effectively improve the battery's cycle performance.

[0038] It should also be explained that, in the context of this application, battery cells and batteries include, but are not limited to, lithium batteries, sodium batteries, magnesium batteries, etc.

[0039] Electrode assembly According to a first aspect, the present application provides an electrode assembly comprising a negative electrode plate, a positive electrode plate, and a separator. Herein, the negative electrode plate comprises a negative electrode film layer, the negative electrode film layer comprising a fluorine-containing polymer. The positive electrode plate comprises a positive electrode film layer, the positive electrode film layer comprising a nitrile-based polymer material.

[0040] This application describes an electrode assembly comprising a negative electrode plate, a positive electrode plate, and a separator, wherein the negative electrode film layer of the negative electrode plate contains a fluorine-containing polymer. Taking a lithium-ion battery containing this electrode assembly as an example, in the formation or cycling process of the lithium-ion battery, the fluorine-containing polymer in the negative electrode film layer participates in the formation of the SEI film, making the SEI film LiF-rich. The LiF effectively improves the stability of the SEI film and enhances the ion transport performance of the SEI film. This reduces polarization at the negative electrode / electrolyte interface during the cycling process and improves the battery's cycling performance.

[0041] Furthermore, the positive electrode film layer of the positive electrode plate contains a nitrile polymer material. Since the nitrile polymer material contains strongly polar cyano groups (-C≡N), the lone pairs of electrons in the strongly polar cyano groups serve well as coordination sites for lithium ions and can effectively increase the dielectric constant of the nitrile polymer material. This improves the ion transport performance at the positive electrode / electrolyte interface. In addition, the lone pairs of electrons in the strongly polar cyano groups have a very strong trapping effect on hydrogen ions in the electrolyte, thereby effectively reducing the concentration of hydrogen ions in the electrolyte and mitigating the adverse effects of the fluorine-containing polymer added to the negative electrode film layer on the positive electrode. Moreover, the cyano groups have good thermal stability, mechanical strength, and electrochemical compatibility, and can interact with the groups on the surface of the positive electrode active material by forming strong hydrogen bonds and dipole-dipole interactions. This effectively stabilizes the structure of the positive electrode active material, further reducing the influence of hydrogen ions in the electrolyte on the positive electrode active material and decreasing the elution of metal ions from the positive electrode active material. The inclusion of a nitrile polymer material in the positive electrode film layer, through the two embodiments described above, effectively reduces the undesirable influence of the fluorine-containing polymer in the negative electrode film layer on the positive electrode, while simultaneously improving the ion transport performance at the positive electrode / electrolyte interface, reducing polarization at the positive electrode / electrolyte interface during the cycle process, and improving the battery's cycle performance.

[0042] In summary, this application enables the effective improvement of ion transport performance at the positive electrode / electrolyte interface and the negative electrode / electrolyte interface by simultaneously adding a fluorine-containing polymer to the negative electrode film layer and a nitrile-based polymer material to the positive electrode film layer. It also reduces the influence of hydrogen ions on the positive electrode / electrolyte interface, ensures the stability of the positive electrode active material, and synergistically improves the battery's cycle performance.

[0043] [Negative electrode plate] In some embodiments, the fluorine-containing polymer includes at least one of polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, polyvinyl fluoride, fluorine-containing polyacrylate fluororubber, fluorine-containing polyester rubber, and fluorosilicone rubber.

[0044] In some of the embodiments described above, several types of fluorine-containing polymers commonly used in the art are specifically listed, and these specific types of fluorine-containing polymers may be used. These fluorine-containing polymers have good ion transport performance and form a stable SEI film, thereby providing the battery with good cycle performance. It should be noted that the fluorine-containing polymers are not limited to the above-mentioned several types, and those skilled in the art can select any known fluorine-containing polymer from the prior art as needed.

[0045] In some embodiments, the mass percentage content of the fluorine-containing polymer in the negative electrode film layer is 0.1% to 2.5%.

[0046] In some of the above embodiments, the mass percentage content of the fluorine-containing polymer in the negative electrode film layer may be further limited to 0.1% to 2.5%. In this case, a stable SEI film with good ion transport performance can be formed, improving the ion transport performance at the negative electrode / electrolyte interface. Furthermore, in this case, relatively few hydrogen ions are generated during the SEI film formation process, the concentration of hydrogen ions in the electrolyte is relatively low, and this does not significantly affect the stability of the positive electrode / electrolyte interface, thereby giving the battery better cycle performance. For example, the mass percentage content of the fluorine-containing polymer in the negative electrode film layer may be within the range of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, or any of the above values. Preferably, the mass percentage content of the fluorine-containing polymer in the negative electrode film layer may be 0.2% to 2%, which results in better battery cycle performance.

[0047] In some embodiments, the negative electrode plate includes a negative electrode current collector, and the negative electrode film layer is placed on at least one surface of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material.

[0048] For example, the negative electrode current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is placed on one or both of the two opposing surfaces of the negative electrode current collector.

[0049] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer material substrate 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 (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0050] In some embodiments, the negative electrode active material may be a negative electrode active material for batteries known in the art. For example, the negative electrode active material may include at least one material from among artificial graphite, natural graphite, soft carbon, hard carbon, silicone-based materials, tin-based materials, and lithium titanate. The silicone-based material may be selected from at least one of elemental silicone, silicone oxide, silicone-carbon composite, silicone-nitrogen composite, and silicone alloy. The tin-based material may be selected from at least one of elemental tin, tin oxide, and tin alloy. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used individually or in combination of two or more.

[0051] In some embodiments, the negative electrode film layer further selectively comprises a first adhesive. The first adhesive 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).

[0052] In some embodiments, the negative electrode film layer further selectively includes a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0053] In some embodiments, the negative electrode film layer further selectively includes other auxiliary agents, such as thickeners (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0054] [Positive electrode plate] In some embodiments, the positive electrode film layer satisfies at least one of the following conditions: 1) the weight-average molecular weight of the nitrile polymer material is 200,000 to 2,000,000; 2) the mass percentage of cyano groups in the nitrile polymer material is 15% to 50%; and 3) the mass percentage content of the nitrile polymer material in the positive electrode film layer is 0.2% to 5%.

[0055] Preferably, the positive electrode film layer satisfies at least one of the following conditions: 1) the weight-average molecular weight of the nitrile polymer material is 400,000 to 1,000,000; 2) the mass percentage of cyano groups in the nitrile polymer material is 25% to 40%; and 3) the mass percentage content of the nitrile polymer material in the positive electrode film layer is 0.5% to 1.5%.

[0056] In some of the embodiments described above, the weight-average molecular weight of the nitrile polymer material in the positive electrode film layer, the mass percentage of cyano groups in the nitrile polymer material, and the mass percentage content of the nitrile polymer material are further limited.

[0057] The weight-average molecular weight of the nitrile polymer material may be between 200,000 and 2,000,000. In this case, the nitrile polymer material disperses more easily on the surface of the positive electrode active material, more effectively reducing the influence of hydrogen ions in the electrolyte on the positive electrode active material, more effectively promoting ion movement, and improving the ion transport rate. Furthermore, the swelling rate of the nitrile polymer material is relatively low, which further improves the stability of the positive electrode film layer, resulting in a battery with better cycle performance. For example, the weight-average molecular weight of the nitrile polymer material may be within the range of 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1,000,000, 1,100,000, 1,200,000, 1,300,000, 1,400,000, 1,500,000, 1,600,000, 1,700,000, 1,800,000, 1,900,000, 2,000,000, or any of the above values. Preferably, the weight-average molecular weight of the nitrile polymer material may be between 400,000 and 1,000,000, in which case the battery's cycle performance is better.

[0058] It should be explained that the weight-average molecular weight of nitrile polymer materials has a known meaning in this art and may be tested using known instruments and methods, for example, by using the GPC method. In this art, the unit of weight-average molecular weight is generally omitted, and unless otherwise specified, the unit of weight-average molecular weight is Daltons.

[0059] The mass percentage of cyano groups in nitrile polymer materials may be 15% to 50%. In this application, since nitrile polymer materials perform the relevant functions mainly through the strong polar cyano groups contained therein in electrode assemblies, the mass percentage of cyano groups in nitrile polymer materials has a certain effect on the battery's cycle performance. When the mass percentage of cyano groups is 15% to 50%, nitrile polymer materials have better thermal stability, mechanical strength, and electrochemical compatibility. Taking lithium-ion batteries as an example, a sufficient amount of cyano groups in the positive electrode film layer coordinating with lithium ions improves the ion transport rate, has a stronger interaction with the positive electrode active material, and has a better trapping effect on hydrogen ions in the electrolyte, thereby providing a better protective effect on the positive electrode active material and improving the battery's cycle performance.

[0060] Furthermore, when the mass percentage of cyano groups is 15% to 50%, the swelling rate in the electrolyte of the nitrile polymer material is relatively small, and the stability of the positive electrode film layer can be improved, thereby improving the battery's cycle performance. For example, the mass percentage of cyano groups in the nitrile polymer material may be within the range of 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, or any of the above values. Preferably, the mass percentage of cyano groups in the nitrile polymer material may be 25% to 40%.

[0061] It should be explained that the mass percentage of cyano groups in nitrile polymer materials has a known meaning in this art and may be tested using known instruments and methods. For example, the mass percentage of cyano groups in nitrile polymer materials can be determined by referring to the test standard GB / T7717.9.

[0062] The mass percentage content of the nitrile polymer material in the positive electrode film layer may be 0.2% to 5%. In this case, the amount of nitrile polymer material dispersed on the surface of the positive electrode active material in the positive electrode film layer is sufficient, thereby allowing the nitrile polymer material to perform its function better. Furthermore, the stability of the positive electrode film layer is relatively good, effectively reducing the problem of film layer delamination due to swelling of the nitrile polymer material, and thus the battery has better cycle performance. For example, the mass percentage content of the nitrile polymer material in the positive electrode film layer may be within the range of 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, 5.0%, or any of the above values. Preferably, the mass percentage content of the nitrile polymer material in the positive electrode film layer may be 0.5% to 1.5%.

[0063] In some embodiments, the nitrile polymer material includes at least one of nitrile rubber, hydrogenated nitrile rubber, carboxyl nitrile rubber, polyacrylonitrile, and vulcanized nitrile rubber.

[0064] In some of the embodiments described above, several types of nitrile polymer materials commonly used in the art are specifically listed, and these specific types of nitrile polymer materials may be used. These nitrile polymer materials improve the ion transport rate at the cathode / electrolyte interface and protect the stability of the cathode / electrolyte interface, thereby giving the battery good cycle performance. It should be noted that the nitrile polymer materials are not limited to the above-mentioned several types, and those skilled in the art can select any known nitrile polymer material from the prior art as needed.

[0065] In some embodiments, the positive electrode film layer further comprises a second adhesive, the second adhesive comprising at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer, sodium carboxymethylcellulose, and styrene-butadiene rubber.

[0066] In some of the embodiments described above, the positive electrode film layer may further contain a second adhesive. This is because nitrile polymer materials, due to their strongly polar cyano groups, have the beneficial effects described above and also possess a certain adhesive effect, making them suitable as an adhesive for the positive electrode film layer. However, compared to the second adhesives listed in the embodiments above, they have a relatively high swelling rate in the electrolyte. If only nitrile polymer materials are used to bond the components of the positive electrode film layer and the positive electrode film layer to the positive electrode current collector, the swelling of the nitrile polymer material during the battery cycle process may lead to poor adhesion, potentially causing the positive electrode film layer and positive electrode current collector to separate, thus reducing the battery's cycle performance. Therefore, in some embodiments, a second adhesive may be added to the positive electrode film layer. The swelling rate of this second adhesive is relatively low, ensuring stable adhesion between the components of the positive electrode film layer and the positive electrode current collector even after long-term cycling, further improving the battery's cycle performance.

[0067] In some embodiments, the positive electrode plate includes a positive electrode current collector, and the positive electrode film layer is provided on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material.

[0068] For example, a positive electrode current collector has two opposing surfaces in the thickness direction of itself, and the positive electrode film layer is placed on one or both of the two opposing surfaces of the positive electrode current collector.

[0069] In some embodiments, the positive electrode current collector may employ a metal foil sheet or a composite current collector. For example, aluminum foil may be employed as the metal foil sheet. The composite current collector may include a polymer material substrate 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 (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (such as substrates of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0070] In some embodiments, the positive electrode active material may employ a positive electrode active material for batteries known in the art. As an example, the positive electrode active material may include at least one material among lithium-containing phosphates having an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and conventional materials that can be used as other battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of lithium transition metal oxides are 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 (which may also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which may also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which may also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2O2 (which may be abbreviated as NCM), LiNi 622 Co 0.8 Co 0.1 Mn 0.1 O2 (which may be abbreviated as NCM), lithium nickel cobalt aluminum oxide (e.g., LiNi 811 Co 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc., but not limited thereto. Examples of olivine-structured lithium-containing phosphates include lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and at least one of a composite material of lithium manganese iron phosphate and carbon, but not limited thereto.

[0071] In some embodiments, the cathode active material may include at least one of lithium iron phosphate, lithium cobalt oxide, Li a Ni x Co y M 1-x-y O b where 0.8 < a < 1.2, 0 < x < 1, 0 < y < 1, 1.8 < b < 2.2, and M is selected from Mn and / or Al.

[0072] In some of the above embodiments, the electrode assembly according to the present application has a good protective effect on the cathode active material, and the cathode interface has relatively good ion transport performance. Therefore, a cathode active material with a higher energy density may be used as needed.

[0073] In some embodiments, the cathode film layer further selectively includes a conductive agent. As an example, 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.

[0074] [Separator] This application does not particularly limit the type of separator, and any known porous structure separator having good chemical and mechanical stability may be selected.

[0075] In some embodiments, the material of the separator may be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and is not particularly limited.

[0076] Manufacturing method for electrode assemblies According to a second aspect, the present application provides a method for manufacturing an electrode assembly, comprising the steps of: forming a negative electrode film layer on at least one side of a negative electrode current collector to obtain a negative electrode plate, wherein the negative electrode film layer comprises a fluorine-containing polymer; and forming a positive electrode film layer on at least one side of a positive electrode current collector to obtain a positive electrode plate, wherein the positive electrode film layer comprises a nitrile-based polymer material.

[0077] This application allows for the addition of a fluorine-containing polymer to the negative electrode film layer and a nitrile-based polymer material to the positive electrode film layer using a general manufacturing method. This results in an electrode assembly of any one embodiment of the first embodiment having any of the beneficial effects of the first embodiment.

[0078] In some embodiments, forming a negative electrode film layer on at least one side of a negative electrode current collector specifically includes: uniformly mixing a negative electrode active material with a fluorine-containing polymer and dispersing the fluorine-containing polymer on the surface of the negative electrode active material to obtain a negative electrode premix; dispersing the negative electrode premix and a first adhesive in a first solvent to obtain a negative electrode slurry; and applying the negative electrode slurry to at least one side of a negative electrode current collector to form a negative electrode film layer.

[0079] In some of the above embodiments, the negative electrode active material may first be pre-mixed with a fluorine-containing polymer, pre-coating the fluorine-containing polymer with the negative electrode active material, which can further effectively improve ion transport efficiency, reduce DC impedance, and enable block formation in the SEI film formation process, as well as increase the toughness and structural stability of the SEI film, thereby improving the battery's cycle performance.

[0080] In some embodiments, the negative electrode premix further includes a first adhesive and a first solvent.

[0081] In some of the embodiments described above, the first adhesive and the first solvent can be added to the negative electrode premix to improve the dispersion effect of the fluorine-containing polymer, thereby making it easier to coat the negative electrode active material and further improving the battery's cycle performance.

[0082] In some embodiments, the types of fluorine-containing polymer, negative electrode active material, first adhesive, and negative electrode current collector may be selected based on the description of the first embodiment.

[0083] In some embodiments, the first solvent may include water, dimethylformamide (DMF), diethylformamide, dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), methanol, ethanol, 1-propanol, 2-propanol (isopropanol), 1-butanol (n-butanol), 2-methyl-1-propanol (isobutanol), 2-butanol (2-butanol), 1-methyl-2-propanol (t-butanol), pentanol, hexanol, heptanol, or octanol, and the diol may include, for example, ethylene glycol, diethylene glycol, triethylene glycol, propyldiol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, hexanediol, glycerol, trim The at least one of the following is included: tyrolpropane, pentaerythritol, sorbitol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, acetone, methyl ethyl ketone, methyl propyl ketone, cyclopentanone, ethyl acetate, γ-butyrolactone, and ε-propiolactone.

[0084] In some embodiments, the negative electrode slurry can be applied to at least one side of the negative electrode current collector, and then a negative electrode film layer can be formed by further processes such as drying and cold pressing.

[0085] In some embodiments, forming a positive electrode film layer on at least one side of a positive electrode current collector specifically includes: uniformly mixing a positive electrode active material with a nitrile polymer material and dispersing the nitrile polymer material on the surface of the positive electrode active material to obtain a positive electrode premix; dispersing the positive electrode premix and a second adhesive in a second solvent to obtain a positive electrode slurry; and applying the positive electrode slurry to at least one side of a positive electrode current collector to form a positive electrode film layer.

[0086] In some embodiments, the positive electrode active material can first be pre-mixed with a nitrile polymer material. Because the cyano groups in the nitrile polymer material have a relatively strong interaction with the positive electrode active material, pre-mixing allows the positive electrode active material to be pre-coated onto the nitrile polymer material, further effectively improving the ion transport efficiency at the positive electrode interface. In addition, the nitrile polymer material on the surface of the positive electrode active material can better capture hydrogen ions, thereby stabilizing the metal elements on the surface of the positive electrode active material, reducing the influence of the fluorine-containing polymer in the negative electrode film layer on the battery performance of hydrogen ions, and further synergistically improving the battery's cycle performance.

[0087] In some embodiments, the cathode premix further contains a second solvent, and the solids content in the cathode premix is ​​80% to 90%.

[0088] In some of the embodiments described above, a second solvent can be added to the positive electrode premix to improve the dispersion effect of the nitrile polymer material, thereby more easily coating the positive electrode active material and further improving the battery's cycle performance. Furthermore, by limiting the solid content in the positive electrode premix, when the solid content is 80% to 90%, the pre-coating effect of the nitrile polymer material on the positive electrode active material is better, thereby better protecting the stability of the positive electrode / electrolyte interface and improving the battery's cycle performance. For example, the solid content in the positive electrode premix may be within the range of 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, or any of the above values. Preferably, the solid content in the positive electrode premix is ​​83% to 86%, at which point the battery's cycle performance is better.

[0089] In some embodiments, the types of nitrile polymer material, positive electrode active material, second adhesive, and positive electrode current collector may be selected based on the description of the first embodiment.

[0090] In some embodiments, the second solvent may include dimethylformamide (DMF), diethylformamide, dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), methanol, ethanol, 1-propanol, 2-propanol (isopropanol), 1-butanol (n-butanol), 2-methyl-1-propanol (isobutanol), 2-butanol (2-butanol), 1-methyl-2-propanol (t-butanol), pentanol, hexanol, heptanol, or octanol, and the diol may be, for example, ethylene glycol, diethylene glycol, triethylene glycol, propyldiol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, hexanediol, glycerol, trimethyl The at least one of the following is rollpropane, pentaerythritol, sorbitol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, acetone, methyl ethyl ketone, methyl propyl ketone, cyclopentanone, ethyl acetate, γ-butyrolactone, and ε-propiolactone.

[0091] In some embodiments, a positive electrode slurry can be applied to at least one side of the positive electrode current collector, and then a positive electrode film layer can be formed by further processes such as drying and cold pressing.

[0092] In some embodiments, the positive electrode plate, negative electrode plate, and separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0093] battery cell According to a third aspect, the present application provides a battery cell which includes an electrode assembly obtained by any one embodiment of the first aspect or an electrode assembly obtained by a manufacturing method of any one embodiment of the second aspect.

[0094] This application provides that the battery cell includes an electrode assembly obtained by a manufacturing method of any one embodiment of the first embodiment or any one embodiment of the second embodiment. The battery cell has the beneficial effects of the first or second embodiment.

[0095] In a similar case, the battery cell further contains an electrolyte, which acts as a conductor of ions between the positive and negative electrodes.

[0096] [Electrolyte] The electrolyte plays a role in conducting ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and it can be selected according to the needs. For example, the electrolyte may be a liquid, a gel, or all-solid.

[0097] In some embodiments, an electrolyte solution is used as the electrolyte. The electrolyte solution comprises an electrolyte salt and a solvent.

[0098] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0099] In some embodiments, the solvent may 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, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0100] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include negative electrode film forming additives, positive electrode film forming additives, and further additives that can improve some of the battery's performance, such as additives that improve the battery's overcharge performance, or additives that improve the battery's high-temperature or low-temperature performance.

[0101] In some embodiments, the battery cell may include an outer casing. This casing may be used to package the electrode assembly and electrolyte.

[0102] In some embodiments, the battery cell casing may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case. The battery cell casing may also be a pouch, such as a bag-shaped pouch. The pouch material may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0103] This application does not particularly limit the shape of the battery cell, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows a rectangular battery cell 5 as an example.

[0104] In some embodiments, referring to Figure 2, the casing may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing and forming a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the cover plate 53 can be fitted over the opening, thereby sealing the housing cavity. The positive electrode plate, negative electrode plate and separator can be formed into an electrode assembly 52 by a winding or lamination process. The electrode assembly 52 is packaged within the housing cavity. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the battery cell 5 may be one or more, and those skilled in the art can specifically select according to their actual needs.

[0105] battery According to a fourth aspect, the present application provides a battery which includes a battery cell of any one embodiment of the third aspect.

[0106] The battery cells may be assembled into a battery according to this application. One embodiment of this application further provides a battery comprising a housing and the battery cells, the battery cells being housed within the housing.

[0107] The number of battery cells included in the above-mentioned battery may be one or more, and a person skilled in the art can select the specific number according to the application and capacity of the battery.

[0108] Furthermore, in the above-mentioned battery, multiple battery cells exist in a form that is assembled to form a battery module. Figure 3 shows an example of a battery module 4. Referring to Figure 3, in the battery module 4, multiple battery cells 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple battery cells 5 may be fixed via fasteners.

[0109] Selectively, the battery module 4 may further include a housing having a housing space, in which a plurality of battery cells 5 are housed.

[0110] Figures 4 and 5 show an example of battery 1. Referring to Figures 4 and 5, battery 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, the upper housing 2 being able to cover the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0111] The above-mentioned battery may be a rechargeable battery or a lithium battery.

[0112] power consumption equipment According to the fifth aspect, the present application provides a power consumption device comprising at least one of a battery cell of any one embodiment of the third aspect or a battery of any one embodiment of the fourth aspect.

[0113] This application further provides a power consumption device, the power consumption device including a battery cell or battery according to this application. The battery cell or battery may be used as a power source for the power consumption device, or as an energy storage unit for the power consumption device. The power consumption device may include, but is not limited to, mobile devices (e.g., mobile phones, laptop computers, etc.), electric vehicles (e.g., 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.

[0114] As the power consumption device, the above-mentioned battery cell or battery can be selected according to the usage demand.

[0115] Figure 6 shows an example of a power-consuming device. This power-consuming device includes a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0116] Other examples of such devices may include mobile phones, tablet computers, and laptop computers. These devices generally require a thin profile and can utilize battery cells as a power source.

[0117] Examples Examples of the present application are described below. The examples described below are illustrative and for interpretive purposes only, and should not be construed as limitations thereon. Where no specific technical or condition is described in the examples, the procedures are carried out in accordance with the technical or condition or product specifications described in the literature in the art. Where the manufacturer of the reagents or equipment used is not specified, they are all commonly available commercial products.

[0118] Example 1-1 (1) Manufacturing of positive electrode plates Lithium cobalt oxide and a nitrile polymer material were dry-blended, and then a small amount of N-methylpyrrolidone was added to obtain a positive electrode premix. The solid content of the positive electrode premix was 85%, and the positive electrode premix was stirred until it became dough-like, stirring for at least 60 minutes. Then, polyvinylidene fluoride and conductive carbon black were added and then uniformly mixed, and after that, sufficient NMP was added and stirred to dissolve and disperse, forming a uniformly dispersed positive electrode slurry. Here, the mass ratio of lithium cobalt oxide, nitrile polymer material, polyvinylidene fluoride and conductive carbon black was 96.8:0.5:1.5:1.2. The nitrile polymer material was nitrile rubber, and the mass percentage of cyano groups in the nitrile polymer material was 20%, with a weight-average molecular weight of 400,000. This positive electrode slurry was uniformly coated onto an aluminum foil positive electrode current collector, and then dried, cold-pressed, and slit to obtain a positive electrode plate.

[0119] (2) Manufacturing of negative electrode plates Artificial graphite, a fluorine-containing polymer emulsion, and sodium carboxymethylcellulose (CMC-Na) were added to deionized water and thoroughly kneaded to obtain a negative electrode premix. Subsequently, an appropriate amount of water and styrene-butadiene rubber (SBR) were added and stirred to disperse the mixture, obtaining a negative electrode slurry. Here, the mass ratio of artificial graphite, fluorine-containing polymer, sodium carboxymethylcellulose, and styrene-butadiene rubber was 96.3:1:1.2:1.5, and the fluorine-containing polymer was polyvinylidene fluoride. This negative electrode slurry was coated onto the copper foil of the negative electrode current collector, and then dried, cold-pressed, and slit to obtain a negative electrode plate.

[0120] (3) Manufacturing of electrolyte At 25°C, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a 1:1:1 volume ratio to obtain a mixed solvent. Then, LiPF6 was dissolved in the mixed solvent to obtain an electrolyte. The concentration of LiPF6 was 1 mol / L.

[0121] (4) Manufacturing of separators A polyethylene (PE) separator substrate with a thickness of 7 μm was selected, and a ceramic coating was applied to a thickness of 3 μm.

[0122] (5) Manufacturing of secondary batteries The positive electrode plate, composite separator, and negative electrode plate were stacked and wound in sequence, then cold-press-formed (during which time the separator was bonded to the electrode plates) to obtain an electrode assembly. This electrode assembly was placed in an outer casing, the manufactured electrolyte was added, and after processes such as packaging, standing, chemical conversion, and aging, a secondary battery was obtained.

[0123] Examples 1-2 to 1-13 The manufacturing of the positive electrode plate, negative electrode plate, electrolyte, separator, and secondary battery is similar to that of Example 1-1, with the only difference being some of the parameter conditions, which can be specifically described in Table 1.

[0124] Examples 1-14 The manufacturing of the electrolyte, separator, and secondary battery was similar to that of Example 1-1, with the only difference being as follows.

[0125] (1) Manufacturing of positive electrode plates Lithium cobalt oxide, a nitrile polymer, polyvinylidene fluoride, and conductive carbon black were added to a sufficient amount of NMP, stirred, dissolved, and dispersed to form a uniformly dispersed positive electrode slurry. Here, the mass ratio of lithium cobalt oxide, nitrile polymer material, polyvinylidene fluoride, and conductive carbon black was 96.8:0.5:1.5:1.2. The nitrile polymer material was nitrile rubber, the mass percentage of cyano groups in the nitrile polymer material was 20%, and the weight-average molecular weight was 400,000. This positive electrode slurry was uniformly coated onto an aluminum foil positive electrode current collector, and then dried, cold-pressed, and slit to obtain a positive electrode plate.

[0126] (2) Manufacturing of negative electrode plates Artificial graphite, a fluorine-containing polymer emulsion, sodium carboxymethylcellulose (CMC-Na), and styrene-butadiene rubber (SBR) were added to sufficient deionized water, stirred, dissolved, and dispersed to form a uniformly dispersed negative electrode slurry. Here, the mass ratio of artificial graphite, fluorine-containing polymer, sodium carboxymethylcellulose, and styrene-butadiene rubber was 96.3:1:1.2:1.5, and the fluorine-containing polymer was polyvinylidene fluoride. This negative electrode slurry was coated onto the copper foil of the negative electrode current collector, and then dried, cold-pressed, and slit to obtain a negative electrode plate.

[0127] Examples 1-15 The manufacturing of the negative electrode plate, electrolyte, separator, and secondary battery was similar to that of Example 1-1, with the only difference being as follows.

[0128] (1) Manufacturing of positive electrode plates Lithium cobalt oxide, a nitrile polymer, polyvinylidene fluoride, and conductive carbon black were added to a sufficient amount of NMP, stirred, dissolved, and dispersed to form a uniformly dispersed positive electrode slurry. Here, the mass ratio of lithium cobalt oxide, nitrile polymer material, polyvinylidene fluoride, and conductive carbon black was 96.8:0.5:1.5:1.2. The nitrile polymer material was nitrile rubber, the mass percentage of cyano groups in the nitrile polymer material was 20%, and the weight-average molecular weight was 400,000. This positive electrode slurry was uniformly coated onto an aluminum foil positive electrode current collector, and then dried, cold-pressed, and slit to obtain a positive electrode plate.

[0129] Examples 1-16 The manufacturing of the positive electrode plate, electrolyte, separator, and secondary battery was similar to that of Example 1-1, with the only difference being as follows.

[0130] (2) Manufacturing of negative electrode plates Artificial graphite, a fluorine-containing polymer emulsion, sodium carboxymethylcellulose (CMC-Na), and styrene-butadiene rubber (SBR) were added to sufficient deionized water, stirred, dissolved, and dispersed to form a uniformly dispersed negative electrode slurry. Here, the mass ratio of artificial graphite, fluorine-containing polymer, sodium carboxymethylcellulose, and styrene-butadiene rubber was 96.3:1:1.2:1.5, and the fluorine-containing polymer was polyvinylidene fluoride. This negative electrode slurry was coated onto the copper foil of the negative electrode current collector, and then dried, cold-pressed, and slit to obtain a negative electrode plate.

[0131] Comparative Example 1-1 The manufacturing of the electrolyte, separator, and secondary battery was similar to that of Example 1-1, with the only difference being as follows.

[0132] (1) Manufacturing of positive electrode plates Lithium cobalt oxide, polyvinylidene fluoride, and conductive carbon black were added to a sufficient amount of NMP, stirred, dissolved, and dispersed to form a uniformly dispersed positive electrode slurry. Here, the mass ratio of lithium cobalt oxide, polyvinylidene fluoride, and conductive carbon black was 97.3:1.5:1.2. This positive electrode slurry was uniformly coated onto the aluminum foil of the positive electrode current collector, and then dried, cold-pressed, and slit to obtain a positive electrode plate.

[0133] (2) Manufacturing of negative electrode plates Artificial graphite, sodium carboxymethylcellulose (CMC-Na), and styrene-butadiene rubber (SBR) were added to sufficient deionized water, stirred, dissolved, and dispersed to form a uniformly dispersed negative electrode slurry. The mass ratio of artificial graphite, sodium carboxymethylcellulose, and styrene-butadiene rubber was 97.3:1.2:1.5. This negative electrode slurry was coated onto the copper foil of the negative electrode current collector, and then dried, cold-pressed, and slit to obtain a negative electrode plate.

[0134] Comparative Example 1-2 The manufacturing of the negative electrode plate, electrolyte, separator, and secondary battery was similar to that of Example 1-1, with the only difference being as follows.

[0135] (1) Manufacturing of positive electrode plates Lithium cobalt oxide, polyvinylidene fluoride, and conductive carbon black were added to a sufficient amount of NMP, stirred, dissolved, and dispersed to form a uniformly dispersed positive electrode slurry. Here, the mass ratio of lithium cobalt oxide, polyvinylidene fluoride, and conductive carbon black was 97.3:1.5:1.2. This positive electrode slurry was uniformly coated onto the aluminum foil of the positive electrode current collector, and then dried, cold-pressed, and slit to obtain a positive electrode plate.

[0136] Comparative Examples 1-3 The manufacturing of the positive electrode plate, electrolyte, separator, and secondary battery was similar to that of Example 1-1, with the only difference being as follows.

[0137] (2) Manufacturing of negative electrode plates Artificial graphite, sodium carboxymethylcellulose (CMC-Na), and styrene-butadiene rubber (SBR) were added to sufficient deionized water, stirred, dissolved, and dispersed to form a uniformly dispersed negative electrode slurry. The mass ratio of artificial graphite, sodium carboxymethylcellulose, and styrene-butadiene rubber was 97.3:1.2:1.5. This negative electrode slurry was coated onto the copper foil of the negative electrode current collector, and then dried, cold-pressed, and slit to obtain a negative electrode plate.

[0138] Examples 2-1 to 2-29 The manufacturing of the positive electrode plate, negative electrode plate, electrolyte, separator, and secondary battery is similar to that of Example 1-1; the only difference is some of the parameter conditions, which can be specifically described in Table 2.

[0139] Test section: 1. Cycle performance At 45°C, the rechargeable battery was charged to 3.65V at a rate of 0.5C, then charged at a constant voltage until the current fell below 0.05C, and finally discharged to 2.5V using a rate of 1C. This full-charge, full-discharge cycle test was performed. This cycle test was continued until the discharge capacity of the rechargeable battery decayed to 80% of its initial capacity, and the number of cycles at this point was recorded.

[0140] 2. Electrolyte HF content test At 25°C, the secondary battery was charged to 3.65V at a rate of 0.5C, then charged at a constant voltage until the current fell below 0.05C, and then discharged to 2.5V using a rate of 1C. After 500 cycles in this full-charge / full-discharge format, the secondary battery was disassembled and the electrolyte was collected. Free H₂O₂ in the electrolyte was determined by HF acid-base titration. + The sample was tested, and approximately 15g was weighed out based on the HF content. An indicator was added, and the initial titration tube volume was recorded. The titration tube volume was also recorded from the start of the titration to the end of the reaction. The HF content was then calculated.

[0141] 3. Co metal ion test During long-term cycling and storage processes, positive electrode metal ions eluted and deposited on the anode (i.e., negative electrode). The metal ion content was measured using inductively coupled plasma (ICP) technology. After the end of cycling or storage, the disassembled anode plates were dried, and trace amounts of anode powder were collected using a polyfluoride spoon. After removal with microwaves, the Co metal ion content in the anode was measured.

[0142] The results for Examples 1-1 to 1-16 and Comparative Examples 1-1 to 1-3 are shown in Table 1, and the results for Examples 2-1 to 2-29 are shown in Table 2.

[0143] [Table 1] TIFF2026519806000003.tif180163

[0144] [Table 2] TIFF2026519806000005.tif229164TIFF2026519806000006.tif218165

[0145] Based on Table 1, the cycle performance of the secondary batteries obtained in each example was significantly better than that of each comparative example, demonstrating that the cycle performance of secondary batteries can be effectively improved by using the electrode assembly according to this application. In Comparative Examples 1-2, adding a fluorine-containing polymer only to the negative electrode plate made the SEI film more stable, improved ionic conductivity, and reduced polarization, resulting in a certain improvement in the battery's cycle performance. However, this increased the HF content in the electrolyte and the cobalt ion content in the anode, leading to poor stability of the positive electrode active material and relatively poor cycle performance. In Comparative Examples 1-3, adding a nitrile-based polymer material only to the positive electrode plate effectively reduced the HF content in the electrolyte and improved the stability of the positive electrode active material. However, this may result in an unstable SEI film, relatively poor ionic conductivity, and relatively poor cycle performance.

[0146] As can be seen by comparing Examples 1-1 to 1-9, by using different types of fluorine-containing polymers and nitrile-based polymer materials, it was possible to effectively improve the cycle performance of secondary batteries in all cases.

[0147] As can be seen by comparing Examples 1-1 and 1-10 to 1-13, the solid content in the positive electrode premix has a certain effect on the cycle performance of the secondary battery, and the battery cycle performance was better when the solid content in the positive electrode premix was 80% to 90%.

[0148] As can be seen by comparing Examples 1-1 and 1-14 to 1-16, premixing of the active material with a fluorine-containing polymer or nitrile-based polymer material in the manufacturing process of the positive and negative electrode plates has a certain effect on the cycle performance of the secondary battery. When the positive electrode slurry and negative electrode slurry were manufactured after premixing the active material with a fluorine-containing polymer or nitrile-based polymer material, the battery cycle performance was better.

[0149] As can be seen by comparing Examples 1-1 and 2-1 to 2-7 based on Table 2, the mass percentage content of the fluorine-containing polymer in the negative electrode film layer has a certain effect on the cycle performance of the secondary battery. The cycle performance of the secondary battery was better when the mass percentage content of the fluorine-containing polymer in the negative electrode film layer was 0.1% to 2.5%, and the cycle performance of the secondary battery was highest when the mass percentage content of the fluorine-containing polymer in the negative electrode film layer was 0.2% to 2%.

[0150] As can be seen by comparing Examples 1-1 and 2-8 to 2-16, the mass percentage content of nitrile polymer material in the positive electrode film layer has a certain effect on the cycle performance of the secondary battery. The cycle performance of the secondary battery was better when the mass percentage content of nitrile polymer material in the positive electrode film layer was 0.2% to 5%, and the cycle performance of the secondary battery was highest when the mass percentage content of nitrile polymer material in the positive electrode film layer was 0.5% to 1.5%.

[0151] As can be seen by comparing Examples 1-1 and 2-17 to 2-23, the mass percentage of cyano groups in nitrile polymer materials has a certain effect on the cycle performance of secondary batteries. When the mass percentage of cyano groups in the nitrile polymer material is 15% to 50%, the cycle performance of secondary batteries is better, and when the mass percentage of cyano groups in the nitrile polymer material is 25% to 40%, the cycle performance of secondary batteries is highest.

[0152] As can be seen by comparing Examples 1-1 and 2-24 to 2-29, the weight-average molecular weight of the nitrile polymer material has a certain effect on the cycle performance of the secondary battery. The cycle performance of the secondary battery was better when the weight-average molecular weight of the nitrile polymer material was between 200,000 and 2,000,000, and the cycle performance was highest when the weight-average molecular weight of the nitrile polymer material was between 400,000 and 1,000,000.

[0153] The possible causes of the above results have already been explained and will not be explained further here.

[0154] It should be noted that this application is not limited to the embodiments described above. The embodiments described above are merely illustrative, and any embodiments that have substantially the same configuration as the technical idea and produce the same effects within the scope of the technical proposal of this application are included within the scope of the technical proposal. Furthermore, other methods that are constructed by adding various modifications to the embodiments that a person skilled in the art could conceive of, and by combining some of the components of the embodiments, are also included within the scope of this application, without departing from the spirit of this application. [Explanation of symbols]

[0155] 1 Battery, 2 Upper casing, 3 Lower casing, 4 Battery module, 5 Battery cell, 51 Case, 52 Electrode assembly, 53 Cover plate

Claims

1. An electrode assembly comprising a negative electrode plate, a positive electrode plate, and a separator, The negative electrode plate includes a negative electrode film layer, and the negative electrode film layer contains a fluorine-containing polymer. An electrode assembly in which the positive electrode plate includes a positive electrode film layer, and the positive electrode film layer contains a nitrile-based polymer material.

2. The electrode assembly according to claim 1, wherein the fluorine-containing polymer includes at least one of polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, polyvinyl fluoride, fluorine-containing polyacrylate fluororubber, fluorine-containing polyester rubber, and fluorosilicone rubber.

3. The electrode assembly according to claim 1 or 2, wherein the mass percentage content of the fluorine-containing polymer in the negative electrode film layer is 0.1% to 2.5%.

4. The positive electrode film layer comprises at least, 1) The weight-average molecular weight of the nitrile polymer material is 200,000 to 2,000,000. 2) The mass percentage of cyano groups in the nitrile polymer material is 15% to 50%. 3) The electrode assembly according to claim 1, which satisfies one of the following conditions: the mass percentage content of the nitrile polymer material in the positive electrode film layer is 0.2% to 5%.

5. The positive electrode film layer comprises at least, 1) The weight-average molecular weight of the nitrile polymer material is 400,000 to 1,000,000. 2) The mass percentage of cyano groups in the nitrile polymer material is 25% to 40%. 3) The electrode assembly according to claim 1, which satisfies one of the following conditions: the mass percentage content of the nitrile polymer material in the positive electrode film layer is 0.5% to 1.5%.

6. The electrode assembly according to claim 4 or 5, wherein the nitrile polymer material comprises at least one of nitrile rubber, hydrogenated nitrile rubber, carboxyl nitrile rubber, polyacrylonitrile, and vulcanized nitrile rubber.

7. The positive electrode film layer further comprises a second adhesive, The electrode assembly according to claim 1, wherein the second adhesive comprises at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer, sodium carboxymethylcellulose, and styrene-butadiene rubber.

8. The positive electrode film layer includes a positive electrode active material, The positive electrode active material is lithium iron phosphate, lithium cobalt oxide, Li ａ Ni ｘ Co ｙ M １－ｘ－ｙ O ｂ It includes at least one of the following: The electrode assembly according to claim 1, where 0.8 < a < 1.2, 0 < x < 1, 0 < y < 1, 1.8 < b < 2.2, and M is selected from Mn and / or Al.

9. A method for manufacturing an electrode assembly, The step of forming a negative electrode film layer on at least one side of a negative electrode current collector to obtain a negative electrode plate, The negative electrode film layer comprises a fluorine-containing polymer, The step of forming a positive electrode film layer on at least one side of a positive electrode current collector to obtain a positive electrode plate, The steps include: the positive electrode film layer comprising a nitrile polymer material; A method for manufacturing an electrode assembly, including the method described above.

10. Forming a negative electrode film layer on at least one side of the negative electrode current collector means, specifically, The negative electrode active material is uniformly mixed with a fluorine-containing polymer, and the fluorine-containing polymer is dispersed on the surface of the negative electrode active material to obtain a negative electrode premix. The negative electrode premix and the first adhesive are dispersed in the first solvent to obtain a negative electrode slurry. The manufacturing method according to claim 9, comprising applying a negative electrode slurry to at least one side of a negative electrode current collector to form a negative electrode film layer.

11. The manufacturing method according to claim 10, wherein the negative electrode premix further comprises a first adhesive and a first solvent.

12. Forming a positive electrode film layer on at least one side of the positive electrode current collector means, specifically, The positive electrode premix is ​​obtained by uniformly mixing the positive electrode active material with a nitrile polymer material and dispersing the nitrile polymer material on the surface of the positive electrode active material. The positive electrode premix and the second adhesive are dispersed in the second solvent to obtain a positive electrode slurry. The manufacturing method according to claim 9, comprising applying a positive electrode slurry to at least one side of a positive electrode current collector to form a positive electrode film layer.

13. The manufacturing method according to claim 12, wherein the positive electrode premix further contains a second solvent, and the solid content in the positive electrode premix is ​​80% to 90%.

14. The manufacturing method according to claim 13, wherein the solid content in the positive electrode premix is ​​83% to 86%.

15. A battery cell comprising an electrode assembly according to any one of claims 1 to 8 or an electrode assembly obtained by a manufacturing method according to any one of claims 9 to 14.

16. A battery, comprising the battery cell described in claim 15.

17. A power consumption device comprising at least one of the battery cell described in claim 15 or the battery described in claim 16.

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