Current collector, positive pole piece and battery

Abstract

The utility model provides a current collector, a positive pole piece and a battery. The current collector comprises a framework and a conductive filler. The framework comprises a net-shaped structure with a plurality of meshes and is used for reducing the contact area of the current collector and other substances in the coating material and reducing heat released by reaction of the current collector and other substances, so that the needling safety of the battery is improved, and thermal runaway of the battery is prevented. And the conductive filler is filled in the meshes and is polymerized with the skeleton. The conductive filler is used for coating the coating material in the positive pole piece, so that the current collector is smoothly coated with the coating material in the positive pole piece, and the current collector and the coating material are combined to form the complete positive pole piece.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a current collector, a positive electrode, and a battery. Background Technology

[0002] A battery is a device that converts chemical energy into electrical energy. During this conversion, a rapid rise in the internal temperature of the battery can lead to thermal runaway, causing the battery to burn or explode. To reduce the probability of thermal runaway during battery use and improve battery safety, batteries before they are released to the market are typically subjected to a nail penetration test, and the safety of the battery is determined based on the results of this test.

[0003] In related technologies, the puncture resistance of batteries is generally improved by reducing the number of electrode layers or optimizing the heat dissipation and pressure relief channels of the module. However, testers have found that these two methods still cannot prevent thermal runaway of the battery. Utility Model Content

[0004] This application provides a current collector, a positive electrode, and a battery to prevent thermal runaway in the battery, thereby improving the battery's needle penetration safety.

[0005] In a first aspect, this application provides a current collector for use on a positive electrode sheet. The current collector may include a framework and a conductive filler. The framework includes a mesh structure with multiple pores. The mesh structure is made of metal. The conductive filler fills the pores and polymerizes with the framework. The conductive filler is used to bond the coating material in the positive electrode sheet.

[0006] According to the first aspect, the current collector includes a framework and a conductive filler polymerized with the framework. The framework includes a mesh structure with multiple pores, which reduces the contact area between the current collector and other substances in the coating material, thereby reducing the heat released from the reaction between the current collector and other substances and preventing thermal runaway of the battery. The conductive filler fills the pores and is used to coat the coating material in the positive electrode sheet, allowing the coating material in the positive electrode sheet to be smoothly coated onto the current collector, thus combining the current collector and the coating material to form a complete positive electrode sheet.

[0007] In one possible design, the outer surface of the skeleton is coated. The coating has higher chemical stability than the skeleton.

[0008] Based on the description of the above embodiments, the chemical stability of the coating on the outer surface of the skeleton is higher than that of the skeleton, preventing the conductive metal in the skeleton 1 from directly contacting other substances in the coating material and releasing heat in the high-temperature environment inside the battery, thereby further reducing the probability of thermal runaway of the battery after the nail penetration test and improving the safety of the battery.

[0009] In one possible design, the skeleton may include a multi-layered mesh structure. The multi-layered mesh structure is stacked along a first direction, which is the thickness direction of the skeleton.

[0010] Based on the description of the above embodiments, the skeleton includes a multi-layer mesh structure stacked along the first direction, which increases the content of conductive metal in the skeleton, thereby enhancing the conductivity of the current collector.

[0011] In one possible design, the mesh aperture is greater than or equal to 2 μm; and the mesh aperture is less than or equal to 800 μm.

[0012] Based on the description of the above embodiments, when the aperture of the mesh is greater than or equal to 2μm and less than or equal to 800μm, the battery can simultaneously possess good conductivity and high safety.

[0013] In one possible design, the surface dyn value of the current collector is greater than or equal to 34 dyn / cm.

[0014] Based on the description of the above embodiments, a surface dyn value of 34 dyn / cm or greater than or equal to the current collector can make the current collector surface smooth, and the conductive filler intact without falling off, so that the coating material in the positive electrode sheet can be smoothly coated on the current collector, thereby combining the current collector and the coating material into a complete positive electrode sheet.

[0015] In one possible design, a metal foil is provided on the side of the current collector, the metal foil being used for welding the electrode tabs.

[0016] Based on the description of the above embodiments, a metal foil is provided on the side of the current collector for welding the tabs of the positive electrode sheet to realize the conduction of current inside and outside the battery.

[0017] In one possible design, the conductive filler comprises a conductive polymer, conductive additives, and a flame retardant. The conductive polymer constitutes 70%-85% of the conductive filler, the conductive additives constitute 5%-15%, and the flame retardant constitutes 10%-35%.

[0018] Based on the description of the above embodiments, increasing the proportion of conductive polymer in the conductive filler can improve the conductivity of the current collector, making it suitable for manufacturing small-capacity batteries with high conductivity requirements. Increasing the proportion of flame retardant in the conductive filler can improve the safety of the current collector, making it suitable for manufacturing large-capacity batteries with high safety requirements.

[0019] Secondly, this application provides a positive electrode sheet, comprising a coating material and a current collector as described in any of the above embodiments. The coating material is applied to both surfaces of the current collector.

[0020] Thirdly, this application provides a battery, including a negative electrode, an electrolyte, and the positive electrode described in the above embodiments.

[0021] The beneficial effects of the positive electrode sheet provided in the second aspect and the battery provided in the third aspect can be found in the first aspect and the beneficial effects of various possible embodiments of the first aspect, and will not be repeated here. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a current collector structure in an embodiment of this application.

[0024] Figure 2 This is a schematic diagram of one structure of the skeleton in an embodiment of this application.

[0025] Figure 3 This is a schematic diagram of one structure of the skeleton in an embodiment of this application.

[0026] Figure 4 This is a schematic diagram of the connection structure between the metal foil and the skeleton in an embodiment of this application.

[0027] Figure 5 This is a schematic diagram of a structure of thickened metal gold in an embodiment of this application.

[0028] Figure 6 This is an exploded view of another structure of the current collector in an embodiment of this application.

[0029] Explanation of reference numerals in the attached figures:

[0030] 100-current collector;

[0031] 1-Frame; 11-Metal wire; 111-Coating; 12-Mesh; 2-Conductive filler; 3-Metal foil;

[0032] X is the first direction. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and drawings of this application are intended to cover without excluding other meanings. The words "a" or "an" do not exclude the presence of multiples.

[0036] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0037] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0038] The directional terms appearing in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. For example, in the description of this application, terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figures. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0039] Furthermore, the descriptions of directions such as the X direction, Y direction, and Z direction used to explain the operation and construction of the components in this embodiment are not absolute but relative. Although these directions are appropriate when the components are in the positions shown in the figure, they should be interpreted differently when these positions change to correspond to the changes.

[0040] Furthermore, the terms "first," "second," etc., in the specification and claims of this application or in the aforementioned drawings are used to distinguish different objects rather than to describe a specific order, and may explicitly or implicitly include one or more of the features.

[0041] In the description of this application, unless otherwise stated, "multiple" means two or more (including two), and similarly, "multiple groups" means two or more (including two groups).

[0042] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, "connection" or "linkage" in mechanical structures can refer to a physical connection, such as a fixed connection, for example, a connection fixed by fasteners, such as a connection fixed by screws, bolts, or other fasteners; a physical connection can also be a detachable connection, such as a snap-fit ​​or interlocking connection; a physical connection can also be an integral connection, such as a connection formed by welding, bonding, or integral molding. In circuit structures, "connection" or "linkage" can refer not only to a physical connection but also to an electrical connection or a signal connection. For example, it can be a direct connection, i.e., a physical connection, or an indirect connection through at least one intermediate component, as long as the circuit is connected; it can also refer to the internal connection of two components. Signal connection can refer not only to signal connection through a circuit but also to signal connection through a media, such as radio waves. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0043] A battery is a device that converts chemical energy into electrical energy. During the process of converting chemical energy into electrical energy, thermal runaway can occur when the internal temperature of the battery rises rapidly, leading to the battery burning or exploding.

[0044] The causes of thermal runaway may include, but are not limited to, the following:

[0045] (1) Internal short circuit: Defects, physical damage, dendrite growth or separator failure during battery manufacturing may cause internal short circuit, which may lead to a sharp rise in local temperature.

[0046] (2) Electrolyte decomposition: At high temperatures, the electrolyte in the battery decomposes to produce gas and release a large amount of heat, which exacerbates thermal runaway.

[0047] To prevent thermal runaway during battery use and improve battery safety, batteries before they are released to the market are typically subjected to a nail penetration test. The results of this test are used to assess the battery's safety. The nail penetration test simulates the battery's safety response when penetrated by a sharp object, particularly its thermal stability and safety protection capabilities under internal short circuit conditions. This verifies whether the battery can effectively prevent thermal runaway under extreme conditions.

[0048] In related technologies, the puncture resistance of batteries is generally improved by reducing the number of electrode layers or optimizing the heat dissipation and pressure relief channels of the module. However, testers have found that these two methods still cannot prevent thermal runaway of the battery.

[0049] Based on this, this application provides a current collector, a positive electrode sheet, and a battery. By designing the current collector as a mesh-like composite structure, the heat released from the reaction between the current collector and other substances is reduced, preventing thermal runaway during battery use, thereby improving the battery's puncture safety. The following is in conjunction with... Figure 1-6 Please provide a detailed explanation.

[0050] Firstly, such as Figure 1 The current collector 100 provided in this application is applied to a positive electrode sheet. The current collector 100 may include a framework 1 and a conductive filler 2. The framework 1 includes a mesh structure with a plurality of mesh openings 12. The conductive filler 2 fills the mesh openings 12 and polymerizes with the framework 1. The conductive filler 2 is used to bond the coating material in the positive electrode sheet.

[0051] The mesh structure of framework 1 can be prepared by, but is not limited to, the following two methods:

[0052] Firstly, the mesh structure of the skeleton 11 can be made by cutting metal foil. Specifically, multiple mesh openings 12 can be cut out from a whole sheet of metal foil. The thickness of the metal foil is less than 13 μm, so that the thickness of the current collector 100 does not exceed the upper limit of conventional dimensions.

[0053] like Figure 2 As shown, the mesh structure of the skeleton 1 can be woven from multiple metal wires 11, and the metal wires 11 overlap during the weaving process. The thickness at the overlapping points is kept less than 13 μm, thus ensuring that the thickness of the current collector 100 does not exceed the upper limit of conventional dimensions. For example, aluminum wire can be used to weave the skeleton. The aluminum wire has a diameter of 6 μm, and the maximum thickness of the skeleton 1 in the thickness direction is 12 μm.

[0054] Furthermore, the mesh 12 can be a planar mesh structure or a three-dimensional mesh structure, and this application does not make a specific limitation. Among them, the three-dimensional mesh structure is an interconnected and penetrating structure formed in three-dimensional space. This structure itself has good mechanical and electrical properties. Therefore, setting the mesh 12 of the skeleton 1 as a three-dimensional mesh structure can improve the conductivity and toughness of the positive electrode sheet in this application.

[0055] Specifically, the mesh structure can be made of aluminum. The selection criteria for the mesh structure material may include: aluminum's good electrical conductivity, its processability, and the fact that the reaction potential of aluminum does not significantly overlap with the operating potential of the battery in this application.

[0056] However, during testing, technicians discovered that the current collector 100 reacts with other substances in the coating material, releasing a large amount of heat and exacerbating thermal runaway. For example, under high-temperature conditions, the current collector 100, made of sheet aluminum foil in the positive electrode, undergoes an aluminothermic reaction with the metal oxides in the coating material, releasing a large amount of heat.

[0057] Based on this, only the mesh structure of the current collector 100 in this application is made of aluminum, and because the mesh structure has multiple mesh openings 12, the aluminum content of the aluminum mesh structure is significantly reduced compared to sheet aluminum foil of the same volume, thus reducing the heat released by the reaction between the current collector 100 and the metal oxide. Furthermore, the mesh structure of the framework 1 includes multiple mesh openings 12, thereby reducing the contact area between the current collector 100 and the aforementioned metal oxide, further reducing the heat released by the reaction between the current collector 100 and other substances, thereby improving battery safety.

[0058] Furthermore, a coating material needs to be applied to the surface of the current collector 100 to prepare a complete positive electrode sheet, thereby ensuring the performance of the battery.

[0059] In order to reduce the contact area between the current collector 100 and the aforementioned metal oxide while still ensuring smooth application of the coating material, such as... Figure 1 As shown, the current collector 100 in this application can reduce the aluminum content and also add conductive filler 2 to the skeleton 1 to ensure that the current collector 100 has a complete coating surface so that the coating material can be smoothly coated on the current collector, thereby preparing a positive electrode sheet with high safety.

[0060] In addition, the conductive filler 2 may include conductive polymers, conductive additives, functional additives, and polymer modifiers.

[0061] The conductive polymer in conductive filler 2 can be 70% to 100%. Specifically, the conductive polymer can be one or more of polypyrrole, polyaniline, polythiophene, polyacetylene, polyphenylene, and their modified materials, including but not limited to polypyrrole, polyaniline, polythiophene, polyacetylene, etc. The conductive polymer is solid at room temperature, resistant to electrolyte corrosion, and has a conductivity of 10. -10 S / cm or higher.

[0062] Therefore, the high conductivity of the conductive polymer can give the current collector 100 good conductivity. Since the content of conductive metal in the mesh structure is reduced, the current collector 100, with its good conductivity, can also be used to ensure the conductivity of the positive electrode in this application.

[0063] The conductive additive can be one or more materials, including but not limited to conductive carbon black, graphite particles, carbon nanotubes, graphene, and metal powder. The conductive additive is resistant to electrolyte corrosion and can increase the conductivity of the conductive filler 2. Specifically, the content of the conductive additive in the conductive filler 2 can be 0% to 30%.

[0064] The functional additives may include, but are not limited to, one or more materials such as flame retardants, expanding agents, heat insulation agents, and microcapsules, which can enable the current collector 100 to acquire the functions corresponding to the properties of the additives. For example, adding a flame retardant to the conductive filler 2 can make the current collector 100 in this application difficult to burn. Specifically, the content of the functional additives in the conductive filler 2 is 0-15%.

[0065] The polymer modifier can be one or more functional materials, including but not limited to dispersants and softeners, which can appropriately improve the toughness of the current collector 100, making it less prone to breakage during processing, thereby improving the production yield of the current collector 100. Specifically, the content of the polymer modifier in the conductive filler 2 can be 0-5%.

[0066] In summary, conductive polymers are used to improve the conductivity of current collector 100, and conductive additives are used to improve the conductivity of conductive filler 2. Flame retardants are used to improve the safety of current collector 100. Polymer modifiers are used to make current collector 100 easier to process.

[0067] Furthermore, the specific methods for adding conductive filler 2 to the skeleton 1 may include: such as Figure 1 and Figure 2 As shown, conductive filler 2 is filled into mesh 12 and polymerized with skeleton 1 to form current collector 100.

[0068] In addition, the conductive polymer can also have adhesive properties, which can be used to smoothly coat the coating material in the positive electrode sheet onto the current collector 100, thereby combining the current collector 100 and the coating material into a complete positive electrode sheet.

[0069] In summary, the current collector 100 provided in this application includes a framework 1 and a conductive filler 2 polymerized with the framework 1. The framework 1 includes a mesh structure with multiple pores 12, which reduces the contact area between the current collector 100 and other substances in the coating material, thereby reducing the heat released by the reaction of the current collector 100 with other substances and preventing thermal runaway of the battery. The conductive filler 2 fills the pores 12 and is used to coat the coating material in the positive electrode sheet, allowing the coating material in the positive electrode sheet to be smoothly coated onto the current collector 100, thus combining the current collector 100 and the coating material to form a complete positive electrode sheet.

[0070] Furthermore, to further improve battery safety, the following improvements can be made to this application:

[0071] In some embodiments, such as Figure 3 As shown, a coating 111 is provided on the outer surface of the skeleton 1. The chemical stability of the coating 111 is higher than that of the skeleton 1.

[0072] Specifically, when the chemical stability of the coating 111 is higher than that of the skeleton, the high temperature environment inside the battery will not cause the coating 111 to melt, thereby preventing the skeleton 1 from being exposed and thus avoiding the conductive metal in the skeleton 1 from reacting with other substances in the coating material and releasing heat.

[0073] Optionally, a 1μm layer of titanium is plated on the surface of the skeleton. Titanium is a silvery-white transition metal with advantages such as high melting point, high strength, and good stability. Therefore, when the coating 111 on the outer surface of the skeleton 1 is titanium, the high-temperature environment inside the battery will not cause the titanium to melt, thereby preventing the skeleton 1 from being exposed and thus avoiding the conductive metal in the skeleton 1 from reacting with other substances in the coating material and releasing heat.

[0074] Specifically, when the conductive metal in the skeleton 1 is aluminum, the reaction potential of titanium is similar to that of aluminum. This prevents aluminum from undergoing an aluminothermic reaction with the metal oxides in the coating material and releasing a large amount of heat, while ensuring that the conductivity of the current collector 100 remains unaffected.

[0075] In summary, the chemical stability of the coating 111 on the outer surface of the frame 1 is higher than that of the frame 1. This prevents the conductive metal in the frame 1 from directly contacting other substances in the coating material and releasing heat under the high temperature environment inside the battery. This further reduces the probability of thermal runaway after the nail penetration test and improves the safety of the battery.

[0076] Furthermore, to ensure the battery meets the requirements for safety and conductivity, this application also includes the following improvements:

[0077] In some embodiments, the aperture of the mesh 12 is greater than or equal to 2 μm; and the aperture of the mesh 12 is less than or equal to 800 μm.

[0078] Specifically, the smaller the aperture of the mesh 12, the higher the content of conductive metal in the framework 1, and the better the conductivity of the battery. Conversely, the larger the aperture of the mesh 12, the smaller the contact area between the conductive metal and other substances in the coating material, and the better the safety of the battery.

[0079] Multiple experiments have shown that when the mesh size is greater than or equal to 2μm and less than or equal to 800μm, the battery can simultaneously possess good conductivity and high safety. Specifically, the mesh size 12 can be 50μm, 200μm, or 700μm.

[0080] Furthermore, in order to improve the smoothness of the current collector, the present application may perform surface treatment on the current collector so that the surface dyn value of the current collector is greater than or equal to 34 dyn / cm.

[0081] The dyne value reflects the surface smoothness of the current collector 100. A higher dyne value indicates a smoother surface. When the dyne value of the current collector 100 is greater than or equal to 34, the current collector 100 has a high degree of smoothness, which increases the surface tension of the current collector 100. This allows the coating material in the positive electrode sheet to be smoothly coated onto the current collector 100 while preventing the conductive filler 2 from falling off, thus combining the current collector 100 and the coating material into a complete positive electrode sheet.

[0082] Specifically, when the surface flatness of the current collector 100 is qualified, it can be expressed as: the number of holes, depressions and protrusions on the current collector 100 per square meter is less than 10.

[0083] The surface treatment process can include, but is not limited to, the following three:

[0084] Process 1: The current collector 100 is surface treated by a roll forming process.

[0085] Process 2: The current collector 100 is surface treated using a surface processing technology.

[0086] Process 3: First, the current collector 100 is surface treated by a surface processing process, and then the current collector 100 is surface treated by a rolling process.

[0087] Furthermore, the surface-treated current collector 100 needs to have a certain degree of toughness so that it can be bent and rolled up to meet the belt carrying requirements of the current collector 100 coating process.

[0088] In summary, the current collector can be surface-treated using any of the following methods: surface processing, rolling, or a combination of surface processing and rolling. This process ensures that the surface dyn value of the current collector is greater than or equal to 34 dyn / cm, resulting in a smooth surface, intact conductive filler without detachment, and successful coating of the positive electrode material onto the current collector. Consequently, the current collector and the coating material are combined to form a complete positive electrode.

[0089] Furthermore, to facilitate the successful fabrication of the current collector 100 and the positive electrode, the following improvements were made in this application:

[0090] In some embodiments, such as Figure 4 As shown, a metal foil 3 is provided on the side of the current collector 100.

[0091] Specifically, tabs need to be welded to both ends of the positive electrode sheet composed of the current collector 100 and the coating material. However, the framework 1 of the current collector 100 is a mesh structure with holes 2. Based on this, metal foils 3 can be respectively provided on both sides of the current collector 100 near the tabs for welding the tabs. Specifically, the tabs are used to enable the conduction of current inside and outside the battery.

[0092] Furthermore, for ease of processing, all sides of the current collector 100 can be provided with metal foil 3 of the same specification. In addition, the material of the metal foil 3 can be the same as that of the frame 1.

[0093] In summary, the current collector 100 has a metal foil 3 on its side for welding the tabs of the positive electrode to enable the conduction of current inside and outside the battery.

[0094] Regarding the current collector 100 for which the skeleton 1 is prepared by braiding metal wire 11, in other embodiments, such as Figure 5 As shown, the diameter of the metal wire 11 is increased so that the metal wire 11 can be used to weld the electrode tab.

[0095] Specifically, the metal wire 11 at the edge of the current collector 100 is thickened so that the thickened metal wire 11 can be used to weld the electrode tab.

[0096] Furthermore, since the framework 1 in the current collector 100 has a mesh structure, the amount of metal material that can be used for conductivity in the current collector 100 is relatively small. In order to further ensure the conductivity of the current collector 100, the following features can be added to the framework 1:

[0097] In some embodiments, such as Figure 6 As shown, the skeleton 1 may include a multi-layered mesh structure. The multi-layered mesh structure is stacked along a first direction X. Wherein, the first direction X is the thickness direction of the skeleton 1.

[0098] According to the description of the above embodiments, the skeleton 1 includes a multi-layer mesh structure stacked along the first direction X, which increases the content of conductive metal in the skeleton 1, thereby enhancing the conductivity of the current collector 100.

[0099] Furthermore, to ensure current continuity between the multi-layered mesh structures, in some embodiments, pressure welding can be performed at the tabs between the multi-layered mesh structures.

[0100] Furthermore, as can be seen from the foregoing, conductive fillers with different component ratios can give the current collector 100 higher conductivity or higher safety, thereby adapting it to batteries of different specifications.

[0101] Based on this, the proportion of conductive polymer in the conductive filler can be 70%-85%, the proportion of conductive additive in the conductive filler can be 5%-15%, and the proportion of flame retardant in the conductive filler can be 10%-35%, thus obtaining conductive fillers with different component ratios, allowing the current collector to meet different performance requirements. The following two examples illustrate this in detail:

[0102] Example 1: The conductive filler comprises a conductive polymer, a conductive additive, and a flame retardant. The conductive polymer accounts for 85% of the conductive filler, the conductive additive accounts for 10%, and the flame retardant accounts for 10%.

[0103] Specifically, the proportions of the conductive fillers are as follows: 85% polypyrrole (conductive polymer), 2.5% conductive carbon black (conductive additive), 2.5% carbon nanotubes (conductive additive), and 10% triphenyl phosphate (flame retardant).

[0104] Example 2: The conductive filler comprises a conductive polymer, a conductive additive, and a flame retardant. The conductive polymer accounts for 70% of the conductive filler, the conductive additive accounts for 5%, and the flame retardant accounts for 25%.

[0105] Specifically, the proportions of the conductive fillers are as follows: 70% iodine-doped polyacetylene (conductive polymer), 2.5% conductive carbon black (conductive additive), 2.5% carbon nanotubes (conductive additive), and 25% ethoxypentafluorocyclotriphosphazene (flame retardant).

[0106] Among them, polypyrrole has better conductivity than iodine-doped polyacetylene, and the proportion of conductive polymer is greater in Example 1.

[0107] Ethoxypentafluorocyclotriphosphazene has a better flame retardant effect than triphenyl phosphate, and the proportion of flame retardant in Example 2 is larger.

[0108] Based on the description of the above embodiments, the conductive polymer is used to improve the conductivity of the current collector. The flame retardant is used to improve the safety of the current collector.

[0109] Therefore, the conductive filler in Example 1 can improve the conductivity of the current collector, making it suitable for manufacturing small-capacity batteries with high conductivity requirements, such as a 20Ah high-nickel ternary 811 pouch battery. Similarly, the conductive filler in Example 1 can improve the safety of the current collector, making it suitable for manufacturing large-capacity batteries with high safety requirements, such as a 560Ah lithium iron phosphate prismatic battery.

[0110] For example, ten 20Ah high-nickel ternary 811 pouch cells are set as Sample 1. The current collector in Sample 1 includes the conductive filler from Example 1.

[0111] Ten 560Ah lithium iron phosphate prismatic batteries were set up as Sample 2. The current collector in Sample 2 included the conductive filler from Example 1.

[0112] Ten 560Ah lithium iron phosphate prismatic batteries were set up as Sample 3. The current collector in Sample 3 included the conductive filler from Example 2.

[0113] A needle prick test was performed on 10 samples (sample 1), 10 samples (sample 2), and 10 samples (sample 3). The standard for the needle prick test can be found in GB / T31485-2015.

[0114] The test results are as follows:

[0115] All 10 samples met the above standards; 2 samples met the above standards; and all 10 samples met the above standards.

[0116] The conclusion that can be drawn from the above test results is:

[0117] Increasing the proportion of conductive polymers in conductive fillers can improve battery conductivity, making it suitable for manufacturing small-capacity batteries with high conductivity requirements. Increasing the proportion of flame retardants in conductive fillers can improve battery safety, making it suitable for manufacturing large-capacity batteries with high safety requirements.

[0118] Secondly, this application provides a positive electrode sheet, comprising a coating material and a current collector as described in any of the above embodiments. The coating material is applied to both surfaces of the current collector.

[0119] Thirdly, this application provides a battery, including a negative electrode, an electrolyte, and the positive electrode described in the above embodiments.

[0120] Those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0121] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A current collector for application to a positive electrode sheet, characterized by, The current collector comprises a framework and a conductive filler; The framework comprises a mesh structure with a plurality of mesh holes, and the mesh structure is made of metal; The conductive filler is filled in the mesh holes and is polymerized with the framework; The conductive filler is used to bond the coating material in the positive electrode tab.

2. The current collector of claim 1, wherein An outer surface of the framework is provided with a plating layer; The chemical stability of the plating layer is higher than that of the framework.

3. The current collector of claim 2, wherein The framework comprises a multi-layer mesh structure; The multi-layer mesh structure is stacked along a first direction; The first direction is the thickness direction of the framework.

4. The current collector of claim 2, wherein The pore size of the mesh hole is greater than or equal to 2 μm; And the pore size of the mesh hole is less than or equal to 800 μm.

5. The current collector of claim 2, wherein The surface of the current collector has an area value greater than or equal to 34 dyn / cm.

6. The current collector of claim 2, wherein The side of the current collector is provided with a metal foil; The metal foil is used for welding the tab.

7. The current collector of any one of claims 1-6, wherein, The conductive filler comprises a conductive polymer, a conductive additive and a flame retardant.

8. A positive electrode sheet characterized by comprising: The coating material and the current collector of any one of claims 1-7 are included; The coating material is coated on both sides of the current collector.

9. A battery, characterized by The negative electrode tab, the electrolyte and the positive electrode tab of claim 8 are included.

Images