Battery cell, battery apparatus, and electric device

Abstract

A battery cell, a battery apparatus, and an electric device, relating to the technical field of batteries. The battery cell comprises: a positive electrode sheet. The positive electrode sheet comprises a composite current collector and a positive electrode film layer arranged on the surface of at least one side of the composite current collector, wherein the loading amount A of the positive electrode film layer is greater than 256 mg / 1540.25 mm2, and the composite current collector comprises a support layer and conductive structure layers arranged on the surfaces of two sides of the support layer. The composite current collector satisfies at least one of the following conditions: the thickness of the support layer is greater than 8 μm; and in the width direction of the composite current collector, the composite current collector comprises a middle region and end regions, wherein the end regions are located at two ends of the middle region, and the total thickness of the conductive structure layers in the end regions is greater than 2 μm. The technical solution of the present application is beneficial to taking into account both the energy density of the battery cell and the manufacturing yield of the battery cell.

Description

Battery cells, battery devices, electrical equipment Cross-references to related applications

[0001] This patent document claims priority and benefit to Chinese Patent Application No. 202510029861.0, filed on January 8, 2025, entitled "Battery Cell, Battery Device, Electrical Equipment". The entire contents of the aforementioned patent application are incorporated herein by reference as a part of the disclosure of this patent document. Technical Field

[0002] This application relates to the field of battery technology, and more specifically, to a battery cell, a battery device, and an electrical appliance. Background Technology

[0003] With increasing environmental pollution, the new energy industry is attracting more and more attention. Within the new energy industry, battery technology is a crucial factor in its development.

[0004] The development of battery technology requires consideration of various design factors, such as energy density, cycle life, capacity, reliability, and the fabrication yield of individual battery cells. Improving the energy density and fabrication yield of individual battery cells is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] This application provides a battery cell, a battery device, and an electrical device that can improve the energy density and manufacturing yield of the battery cell.

[0006] In a first aspect, a battery cell is provided, comprising: a positive electrode sheet, the positive electrode sheet including a composite current collector and a positive electrode film layer disposed on at least one surface of the composite current collector, wherein the loading A of the positive electrode film layer is greater than 256 mg / 1540.25 mm². 2 The composite current collector includes a support layer and conductive structural layers disposed on both sides of the support layer; wherein the composite current collector satisfies at least one of the following conditions: the thickness of the support layer is greater than 8 μm; along the width direction of the composite current collector, the composite current collector includes a central region and an end region, the end regions are located at both ends of the central region, and the total thickness of the conductive structural layers in the end regions is greater than 2 μm.

[0007] Because composite current collectors are lightweight and soft, during the drying process of composite current collectors coated with positive electrode slurry, the solvent evaporation in the positive electrode slurry causes the edges of the composite current collector to peel and wrinkle. Furthermore, increasing the loading of active material per unit area further exacerbates the peeling and wrinkling. In this embodiment, the loading A of the positive electrode film layer is set to be greater than 256 mg / mm².2 With a support layer thickness greater than 8 μm and / or a conductive structure layer total thickness greater than 2 μm in the end region, the risk of electrode wrinkling can be reduced while ensuring a high coating amount, and the battery cell has both high energy density and high fabrication yield.

[0008] In some embodiments, the elastic modulus G of the composite current collector along its width direction satisfies: 3500MPa≤G≤9000MPa. This reduces the risk of wrinkling of the composite current collector during electrode fabrication, thus improving the yield rate of battery cells.

[0009] In some embodiments, the elastic modulus of the end region is greater than that of the middle region.

[0010] By setting the elastic modulus of the end region to be greater than that of the middle region, the risk of wrinkling of the electrode in the end region can be reduced, and the battery cell has a higher preparation yield.

[0011] In some embodiments, along the thickness direction of the composite current collector, the conductive structure layer in the end region includes a first conductive layer, a third conductive layer, a fourth conductive layer, and a second conductive layer disposed sequentially, and the conductive structure layer in the middle region includes the first conductive layer and the second conductive layer.

[0012] Compared to the support layer, the third and fourth conductive layers have higher strength and elastic modulus. By setting the third and fourth conductive layers in the end region, the elastic modulus of the composite current collector in the end region can be improved, the risk of the electrode wrinkling in the end region can be reduced, and the battery cell has a higher fabrication yield.

[0013] In some embodiments, the thickness of the third conductive layer and / or the fourth conductive layer at the first end is greater than or equal to the thickness of the third conductive layer and / or the fourth conductive layer at the second end, the first end being an end along the width direction of the composite current collector, the end region being away from the middle region, and the second end being an end along the width direction of the composite current collector, the end region being close to the middle region.

[0014] The thickness of the third conductive layer and / or the fourth conductive layer at the first end is greater than or equal to the thickness of the third conductive layer and / or the fourth conductive layer at the second end, which facilitates obtaining a composite current collector with a larger elastic modulus in the end region.

[0015] In some embodiments, the thickness of the third conductive layer and / or the fourth conductive layer gradually decreases along the direction from the end region to the middle region. This helps to reduce the difficulty of fabricating the third conductive layer and / or the fourth conductive layer, and the end region of the composite current collector has a larger elastic modulus.

[0016] In some embodiments, the third conductive layer and / or the fourth conductive layer are rectangular in shape. This helps to reduce the fabrication complexity of the third conductive layer and / or the fourth conductive layer, and the end region of the composite current collector has a larger elastic modulus.

[0017] In some embodiments, the thickness of the third conductive layer and / or the fourth conductive layer at the first end is 0.5 μm to 3 μm.

[0018] When the thickness of the third conductive layer and / or the fourth conductive layer at the first end is greater than or equal to 0.5 μm, the thickness of the third conductive layer and / or the fourth conductive layer can effectively improve the elastic modulus of the end region of the composite current collector and reduce the risk of wrinkling in the end region of the electrode sheet. When the thickness of the third conductive layer and / or the fourth conductive layer at the first end is less than or equal to 3 μm, the risk of short circuit caused by the overlap of the positive and negative electrode sheets in extreme cases can be reduced. By setting the thickness of the third conductive layer and / or the fourth conductive layer at the first end to be 0.5 μm to 3 μm, both the fabrication efficiency and reliability of the battery cell can be considered.

[0019] In some embodiments, the thickness of the third conductive layer and / or the fourth conductive layer at the first end is 0.8 μm to 1.5 μm. This allows for a further balance between the fabrication efficiency and reliability of the battery cell.

[0020] In some embodiments, the dimensions of the third conductive layer and / or the fourth conductive layer are 0.05L0 to 0.12L0 along the width direction of the composite current collector, where L0 is the dimension of the first conductive layer and / or the second conductive layer along the width direction of the composite current collector.

[0021] When the dimensions of the third conductive layer and / or the fourth conductive layer are greater than or equal to 0.05L0, the end region of the composite current collector has a certain size, which can effectively improve the elastic modulus of the end region of the composite current collector and reduce the risk of wrinkling in the end region of the electrode. When the dimensions of the third conductive layer and / or the fourth conductive layer are less than or equal to 0.12L0, the risk of short circuit caused by the overlap of the positive and negative electrode sheets in extreme cases can be reduced. By setting the dimensions of the third conductive layer and / or the fourth conductive layer to 0.05L0 to 0.12L0, both the fabrication yield and reliability of the battery cell can be considered.

[0022] In some embodiments, the dimensions of the third conductive layer and / or the fourth conductive layer are 5 mm to 12 mm along the width direction of the composite current collector. This allows for a further balance between the fabrication efficiency and reliability of the battery cells.

[0023] In some embodiments, 4500MPa≤G≤6000MPa. This results in a composite current collector having a larger elastic modulus, a lower risk of electrode wrinkling, and a higher yield rate for the battery cell.

[0024] In some embodiments, 310mg / 1540.25mm 2 ≤A≤450mg / 1540.25mm 2 In this way, the loading of active material per unit area is large, and the risk of electrode wrinkling is low, which can balance the preparation efficiency and volumetric energy density of the battery cell.

[0025] In some embodiments, the thickness of the first conductive layer and / or the second conductive layer is 0.8 μm to 1.2 μm, and the thickness of the support layer is 6 μm to 10 μm. Thus, when the elastic modulus of the end region is greater than that of the middle region, the first conductive layer, the second conductive layer, and the support layer have a smaller thickness, which is beneficial for improving the reliability and volumetric energy density of the battery cell.

[0026] In some embodiments, along the thickness direction of the composite current collector, the conductive structure layer in the end region includes a first conductive layer and a second conductive layer, and the conductive structure layer in the middle region includes the first conductive layer and the second conductive layer. Thus, along the thickness direction of the composite current collector, a first conductive layer, a support layer, and a second conductive layer are sequentially arranged. This composite current collector has a relatively simple structure, is easy to manufacture, and, by adjusting the thickness of the support layer or the first and second conductive layers, also has a lower risk of wrinkling.

[0027] In some embodiments, the thickness of the first conductive layer and / or the second conductive layer is 1.2 μm to 1.5 μm. This results in a larger thickness for the first and / or second conductive layers, leading to a higher elastic modulus in the composite current collector, which helps reduce the risk of wrinkling in the composite current collector.

[0028] In some embodiments, the thickness of the support layer is 6 μm to 10 μm. This results in a support layer with a relatively small thickness, and the first and second conductive layers have suitable thicknesses, which is beneficial for improving the elastic modulus of the composite current collector and reducing the risk of short circuits caused by the overlap of the positive and negative electrode sheets in extreme cases. This allows the battery cell to achieve both high fabrication yield and high reliability.

[0029] In some embodiments, 3600MPa≤G≤5000MPa. This results in a composite current collector having a larger elastic modulus, a lower risk of electrode wrinkling, and a higher yield rate for the battery cell.

[0030] In some embodiments, 280mg / 1540.25mm 2 ≤A≤390mg / 1540.25mm 2 In this way, the loading of active material per unit area is large, and the risk of electrode wrinkling is low, which can balance the preparation efficiency and volumetric energy density of the battery cell.

[0031] In some embodiments, the thickness of the support layer is 10 μm to 15 μm. This results in a larger support layer, a higher elastic modulus for the composite current collector, a lower risk of electrode wrinkling, and a higher yield rate for the battery cell.

[0032] In some embodiments, the thickness of the first conductive layer and / or the second conductive layer is 0.5 μm to 1.0 μm. This results in a smaller thickness for both the first and second conductive layers, reducing the risk of short circuits caused by the overlap of the positive and negative electrode plates in extreme cases, and allowing the battery cell to achieve both high fabrication yield and high reliability.

[0033] In some embodiments, 4000MPa≤G≤5000MPa. This results in a composite current collector with a larger elastic modulus, a lower risk of electrode wrinkling, and a higher yield rate for the battery cell.

[0034] In some embodiments, 280mg / 1540.25mm 2 ≤A≤340mg / 1540.25mm 2 In this way, the loading of active material per unit area is large, and the risk of electrode wrinkling is low, which can balance the preparation efficiency and volumetric energy density of the battery cell.

[0035] In some embodiments, the positive electrode sheet further includes a positive electrode tab, which protrudes from the composite current collector along the width direction of the composite current collector; the positive electrode sheet further includes an insulating layer, which is closer to the positive electrode tab than the positive electrode film layer along the width direction of the composite current collector.

[0036] The addition of an insulating layer can reduce the risk of short circuits caused by the overlap of the positive and negative electrode plates, which helps to improve the reliability of the battery cell.

[0037] In some embodiments, the positive electrode film layer includes a positive electrode active material, which includes a lithium phosphate.

[0038] Lithium phosphates have high structural stability, and lithium phosphate battery cells have superior cycle performance and reliability. Furthermore, by setting the elastic modulus of the composite current collector, the positive electrode can be coated with more active material, and the battery cell also has a high volumetric energy density.

[0039] In some embodiments, the lithium-containing phosphate includes lithium iron phosphate.

[0040] In some embodiments, the lithium-containing phosphate satisfies at least one of the following conditions:

[0041] The compacted density P1 of the lithium phosphate powder at 3T satisfies: 2.35 g / cm³. 3 ≤P1≤2.65g / cm 3 ;

[0042] The discharge capacity Q0 of the lithium phosphate at 0.1C satisfies: 157.0 mAh / g ≤ Q0 ≤ 160.0 mAh / g;

[0043] The initial coulombic efficiency K of the lithium phosphate satisfies: 99% ≤ K ≤ 100%;

[0044] The volume average particle size Dv50 of the lithium phosphate satisfies: 0.5μm≤Dv50≤3μm.

[0045] The compaction density of lithium phosphate powder meets the above range, the positive electrode sheet can have a high compaction density, and the battery cell has a high energy density; the discharge specific capacity of lithium phosphate at 0.1C meets the above range, and the battery cell has a high energy density; the initial coulombic efficiency of lithium phosphate meets the above range, and the battery cell has a high capacity.

[0046] In some embodiments, the lithium-containing phosphate satisfies at least one of the following conditions:

[0047] The water content B of the lithium phosphate satisfies: 0 ≤ B ≤ 500 ppm;

[0048] The volume average particle size Dv50 of the lithium phosphate satisfies: 0.5μm≤Dv50≤3μm;

[0049] The particle size distribution span of the lithium phosphate satisfies: (Dv90-Dv10) / Dv50≤3.5.

[0050] The water content of lithium phosphates within the above range can reduce the wrinkling of the electrode sheets during the drying process, which is beneficial to improving the yield of battery cells. The volume average particle size of lithium phosphates within the above range can reduce the wrinkling of the electrode sheets during the drying process, which is beneficial to improving the yield of battery cells. The particle size distribution range of lithium phosphates within the above range can reduce the wrinkling of the electrode sheets during the drying process, which is beneficial to improving the yield of battery cells.

[0051] In some embodiments, the lithium-containing phosphate satisfies at least one of the following conditions:

[0052] The volume average particle size Dv50 of the lithium phosphate satisfies: 1μm≤Dv50≤3μm;

[0053] The particle size distribution span of the lithium phosphate satisfies: (Dv90-Dv10) / Dv50≤2.6.

[0054] The above technical solution is conducive to further reducing the wrinkling degree of the electrode sheet during the drying process and improving the preparation yield of the battery cell.

[0055] In some embodiments, the lithium-containing phosphate satisfies at least one of the following conditions:

[0056] The volume average particle size Dv50 of the lithium phosphate satisfies: 2μm≤Dv50≤3μm;

[0057] The particle size distribution span of the lithium phosphate satisfies: (Dv90-Dv10) / Dv50≤2.1.

[0058] The above technical solution is conducive to further reducing the wrinkling degree of the electrode sheet during the drying process and improving the preparation yield of the battery cell.

[0059] In some embodiments, the compaction density P2 of the positive electrode sheet satisfies: 2.55 g / cm³ 3 ≤P2≤2.8g / cm 3 In this way, the positive electrode sheet has a high compaction density, and the battery cell has a high energy density.

[0060] In some embodiments, the volumetric energy density of the battery cell is greater than or equal to 400 Wh / L. Thus, the battery cell has a high energy density.

[0061] In a second aspect, a battery device is provided, comprising: a plurality of battery cells as described in the first aspect or any one of the embodiments of the first aspect.

[0062] Thirdly, an electrical device is provided, comprising: a battery cell as described in the first aspect or any embodiment of the first aspect, or a battery device as described in the second aspect, wherein the battery cell or battery device is used to store or provide electrical energy. Attached Figure Description

[0063] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0064] Figure 1 is a structural schematic diagram of a vehicle according to an embodiment of this application;

[0065] Figure 2 is a schematic diagram of a battery device according to an embodiment of this application;

[0066] Figure 3 is a schematic diagram of a single battery cell according to an embodiment of this application;

[0067] Figure 4 is a schematic diagram of a composite current collector according to an embodiment of this application;

[0068] Figure 5 is a schematic diagram of a composite current collector from another perspective of an embodiment of this application;

[0069] Figure 6 is a schematic diagram of the positive electrode sheet according to an embodiment of this application;

[0070] Figure 7 is a cross-sectional view of the positive electrode plate in Figure 6 along the AA direction;

[0071] Figure 8 is a schematic diagram of a composite current collector according to an embodiment of this application;

[0072] Figure 9 is a schematic diagram of a composite current collector according to an embodiment of this application;

[0073] Figure 10 is a schematic diagram of a composite current collector according to an embodiment of this application;

[0074] Figure 11 is a schematic diagram of a composite current collector according to an embodiment of this application;

[0075] Figure 12 is a schematic diagram of a composite current collector according to an embodiment of this application;

[0076] Figure 13 is a schematic diagram of the positive electrode sheet according to an embodiment of this application.

[0077] Reference numerals: 1: Vehicle; 10: Battery device; 30: Controller; 40: Motor; 11: Housing; 111: First housing section; 112: Second housing section; 3: Battery cell; 31: Housing; 32: End cap assembly; 33: Electrode assembly; 34: Connecting member; 331: Tab; 330: Electrode assembly body; 322: Electrode terminal; 5: Positive electrode plate; 50: Composite current collector; 500: Support layer; 530: Conductive structure layer; 501: First conductive layer; 502: Second conductive layer; 503: Third conductive layer; 504: Fourth conductive layer; 602: Positive electrode tab; 70: Insulating layer; 60: Positive electrode film layer. Detailed Implementation

[0078] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0079] 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 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.

[0080] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0081] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0082] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0083] In this application, 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, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0084] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0085] In this application, "multiple" refers to two or more (including two), and similarly, "multiple groups" refers to two or more (including two), and "multiple pieces" refers to two or more (including two).

[0086] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active material and continue to be used after the battery cell has been discharged.

[0087] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0088] In some embodiments, the battery cell in this application can be a metal battery. Specifically, the metal battery may include lithium metal secondary batteries, sodium metal batteries, or magnesium metal batteries, etc. This application does not limit this.

[0089] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0090] In some embodiments, the positive electrode can be a positive electrode sheet, which can include a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0091] In some embodiments, the negative electrode may be a negative electrode sheet, which may include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0092] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0093] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0094] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride, and ceramic.

[0095] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0096] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0097] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0098] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc. The housing includes a shell and end caps.

[0099] The battery mentioned in the embodiments of this application may be a single physical module comprising one or more battery cells to provide higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or mixed via a busbar.

[0100] In some embodiments, the battery device may be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0101] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0102] In some embodiments, the battery device may be located within an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0103] The development of battery technology requires consideration of multiple design factors, such as yield, production capacity, energy density, capacity retention, discharge capacity, charge / discharge rate, reliability, and first-cycle charge capacity. In the manufacturing process of a battery cell, electrodes are first prepared, and then the prepared electrodes, along with separators and other components, are assembled into an electrode assembly. This assembly is then processed through casing, electrolyte injection, and other steps to obtain the battery cell. In the electrode preparation process, a slurry is coated onto the surface of the current collector, followed by drying, rolling, and cutting to obtain the electrode. Composite current collectors, as a novel type of current collector, are being used in battery technology due to their lightweight characteristics. However, in the process of preparing electrodes using composite current collectors, they are more prone to folding and wrinkling compared to conventional current collectors (such as copper foil or aluminum foil), which is detrimental to improving the yield of the battery cell. Furthermore, as the requirements for energy density increase, the coating weight in the electrode gradually increases, and this increased coating weight exacerbates wrinkling of the electrode.

[0104] In view of this, this application provides a battery cell in which the positive electrode film layer of the positive electrode sheet has a load per unit area greater than 256mg / 1540.25mm². 2 By adjusting the thickness of the support layer and / or the conductive structure layer in the composite current collector, the risk of electrode folding and wrinkling can be reduced while taking into account the large coating weight, which helps to improve the energy density and preparation yield of the battery cell.

[0105] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery devices.

[0106] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical equipment.

[0107] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0108] For example, as shown in Figure 1, which is a structural schematic diagram of a vehicle according to one embodiment of this application, vehicle 1 can be a gasoline vehicle, a natural gas vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A motor 40, a controller 30, and a battery device 10 can be installed inside vehicle 1. The controller 30 is used to control the battery device 10 to supply power to the motor 40. For example, the battery device 10 can be installed at the bottom, front, or rear of vehicle 1. The battery device 10 can be used to power vehicle 1. For example, the battery device 10 can serve as the operating power source for vehicle 1, for example, for the electrical system of vehicle 1, such as for the power requirements of vehicle 1's starting, navigation, and operation. In another embodiment of this application, the battery device 10 can not only serve as the operating power source for vehicle 1, but also as the driving power source for vehicle 1, replacing or partially replacing gasoline or natural gas to provide driving power for vehicle 1.

[0109] Figure 2 shows a partial structural schematic diagram of the battery device 10 according to an embodiment of this application. For example, as shown in Figure 2, the battery device 10 according to this application embodiment may include multiple battery cells 3 to meet different power usage requirements. The shape of the battery cell 3 according to this application embodiment can be set according to actual application. For example, the battery cell 3 can be cylindrical, or it can be a cuboid as shown in Figure 2 or other shapes. This application embodiment is not limited to these.

[0110] It should be understood that, as shown in FIG. 2, the battery device 10 of this embodiment may further include a housing 11, which can be used to accommodate multiple battery cells 3. The housing 11 of this embodiment has a hollow internal structure, and the multiple battery cells 3 are accommodated within the housing 11. The housing 11 may include two parts, referred to herein as a first housing portion 111 and a second housing portion 112, which are fastened together. The shapes of the first housing portion 111 and the second housing portion 112 can be determined according to the shape of the components accommodated internally, for example, according to the shape of the combination of the multiple battery cells 3 accommodated internally. At least one of the first housing portion 111 and the second housing portion 112 has an opening. For example, as shown in Figure 2, the first housing portion 111 and the second housing portion 112 can both be hollow cuboids with one open face. The openings of the first housing portion 111 and the second housing portion 112 are opposite to each other, and the first housing portion 111 and the second housing portion 112 are interlocked to form a housing 11 with a closed cavity, which can be used to accommodate multiple battery cells 3. The multiple battery cells 3 are connected in parallel, series, or mixed and placed inside the housing 11 formed by the interlocking of the first housing portion 111 and the second housing portion 112.

[0111] For example, unlike what is shown in Figure 2, only one of the first housing portion 111 and the second housing portion 112 may be a hollow cuboid with an opening, while the other is plate-shaped to cover the opening. Taking the second housing portion 112 as a hollow cuboid with one opening, and the first housing portion 111 as a plate-shaped example, then the first housing portion 111 covers the opening of the second housing portion 112 to form a housing 11 with a closed chamber, which can be used to accommodate multiple battery cells 3.

[0112] [Battery cell]

[0113] Figure 3 is a schematic diagram of a single battery cell according to an embodiment of the present application; Figure 4 is a schematic diagram of a composite current collector according to an embodiment of the present application; Figure 5 is a schematic diagram of a composite current collector from another perspective according to an embodiment of the present application; Figure 6 is a schematic diagram of a positive electrode sheet according to an embodiment of the present application; and Figure 7 is a cross-sectional schematic diagram of the positive electrode sheet in Figure 6 along the AA direction.

[0114] This application provides a battery cell. For example, as shown in Figures 3 to 7, the battery cell 3 includes a positive electrode 5, which includes a composite current collector 50 and a positive electrode film layer 60 disposed on at least one side surface of the composite current collector 50.

[0115] The composite current collector 50 has two opposing surfaces along its thickness direction. The positive electrode film layer 60 can be disposed on one side surface of the composite current collector 50 or on both sides surface of the composite current collector 50.

[0116] The positive electrode film 60 can cover the entire surface area of ​​the composite current collector 50, or it can cover a part of the surface area of ​​the composite current collector 50.

[0117] The loading A of the positive electrode film layer 60 is greater than 256 mg / 1540.25 mm. 2 .

[0118] The loading A of the positive electrode film layer 60 can be 258 mg / 1540.25 mm. 2 270mg / 1540.25mm 2 280mg / 1540.25mm 2 290mg / 1540.25mm 2 300mg / 1540.25mm 2 310mg / 1540.25mm 2 330mg / 1540.25mm 2 340mg / 1540.25mm 2 350mg / 1540.25mm 2 360mg / 1540.25mm 2380mg / 1540.25mm 2 400mg / 1540.25mm 2 420mg / 1540.25mm 2 450mg / 1540.25mm 2 480mg / 1540.25mm 2 500mg / 1540.25mm 2 550mg / 1540.25mm 2 600mg / 1540.25mm 2 Or any value within the above range.

[0119] The composite current collector 50 includes a support layer 500 and conductive structural layers 530 disposed on both sides of the support layer 500.

[0120] A conductive structural layer 530 is provided on both sides of the support layer 500 along the thickness direction of the composite current collector 50.

[0121] The material of the support layer 500 can be an insulating material or a polymer material. For example, the material of the support layer 500 includes at least one of polyethylene terephthalate (PET), polypropylene (PP), and polyimide (PI).

[0122] The conductive structural layer 530 is made of metallic materials, such as copper, aluminum, or alloys.

[0123] Wherein, the composite current collector 50 satisfies at least one of the following conditions:

[0124] The thickness of the support layer 500 is greater than 8μm;

[0125] Along the width direction of the composite current collector 50, the composite current collector 50 includes a central region and an end region, the end regions are located at both ends of the central region, and the total thickness of the conductive structure layer 530 in the end region is greater than 2 μm.

[0126] As an example, as shown in Figures 6 and 7, the positive electrode 5 includes a composite current collector 50 and a positive electrode tab 602. The positive electrode tab 602 protrudes from the composite current collector 50, and the width direction of the composite current collector 50 is the same as the direction in which the positive electrode tab 602 protrudes from the composite current collector 50.

[0127] The width direction of the composite current collector 50 can be the y-direction shown in Figures 5 and 6.

[0128] As an example, the dimension of the composite current collector 50 in the width direction is smaller than the dimension of the composite current collector 50 in the length direction.

[0129] The thickness of the support layer 500 can be 8.5μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm or any value within the above range; the total thickness of the conductive structure layer 530 in the end region can be 2.2μm, 2.5μm, 2.8μm, 2.9μm, 3.0μm, 3.5μm, 3.8μm, 4.0μm, 4.2μm, 4.5μm, 5.0μm or any value within the above range.

[0130] The composite current collector includes a support layer. The material of the support layer is lighter and softer than that of the conductive structure layer. Therefore, the composite current collector itself is lighter and softer than traditional current collectors (such as aluminum foil).

[0131] During the drying process of the composite current collector coated with positive electrode slurry, the composite current collector is heated, and the solvent in the slurry evaporates. The end region of the composite current collector is subjected to stress along the width direction of the composite current collector away from the end region, making the end region of the composite current collector prone to warping and wrinkling. In addition, the increase in the unit area loading of active material will make the warping and wrinkling phenomena more obvious. Here, "wrinkling" can be understood as the unevenness and folding phenomena that appear on the surface of the composite current collector 50.

[0132] In this embodiment, the loading A of the positive electrode film layer is set to be greater than 256 mg / mm². 2 With a support layer thickness greater than 8 μm and / or a conductive structure layer total thickness greater than 2 μm in the end region, the composite current collector end region can be improved to resist wrinkling while maintaining a high coating amount, reducing the risk of electrode wrinkling, and the battery cell has both high energy density and high fabrication yield.

[0133] In some embodiments, along the width direction of the composite current collector 50, the elastic modulus G of the composite current collector 50 satisfies: 3500MPa≤G≤9000MPa.

[0134] The elastic modulus of the composite current collector 50 reflects its ability to resist deformation. The higher the elastic modulus of the composite current collector, the less likely the electrode or composite current collector is to wrinkle.

[0135] The elastic modulus G of the composite current collector 50 along the width direction can be 3500MPa, 3800MPa, 4000MPa, 4200MPa, 4500MPa, 4800MPa, 5000MPa, 5500MPa, 6000MPa, 6500MPa, 7000MPa, 7500MPa, 8000MPa, 8500MPa, 9000MPa or any value within the above range.

[0136] When G is greater than or equal to 3500 MPa, the composite current collector 50 has a large elastic modulus along the width direction, and the composite current collector 50 has enhanced resistance to deformation. During the preparation of electrode sheets or battery cells, the risk of wrinkling of the composite current collector 50 is reduced, which helps to improve the preparation yield of battery cells. When G is less than or equal to 9000 MPa, it is convenient to prepare the composite current collector.

[0137] In some embodiments, the elastic modulus of the end region is greater than that of the middle region.

[0138] Along the width direction of the composite current collector 50, the end regions are located at both ends of the middle region.

[0139] By setting the elastic modulus of the end region to be greater than that of the middle region, the risk of wrinkling of the positive electrode 5 in the end region can be reduced, and the battery cell has a higher preparation yield.

[0140] Figure 8 is a schematic diagram of a composite current collector according to an embodiment of this application. In some embodiments, for example, as shown in Figure 8, along the thickness direction of the composite current collector 50 (e.g., the z-direction in the figure), the conductive structure layer in the end region includes a first conductive layer 501, a third conductive layer 503, a fourth conductive layer 504, and a second conductive layer 502 disposed sequentially, and the conductive structure layer in the middle region includes a first conductive layer 501 and a second conductive layer 502.

[0141] The third conductive layer 503 and the fourth conductive layer 504 can have shapes in the yoz plane that are rectangles, circles, triangles, arcs, and combinations of straight lines, or other irregular shapes.

[0142] The third conductive layer 503 and the fourth conductive layer 504 may have the same shape or different shapes. As an example, the third conductive layer 503 and the fourth conductive layer 504 have the same shape.

[0143] The third conductive layer 503 and the fourth conductive layer 504 can be made of the same material as the first conductive layer 501 and the second conductive layer 502, or they can be made of different materials. As an example, the third conductive layer 503 and the fourth conductive layer 504 can be made of the same material as the first conductive layer 501 and the second conductive layer 502.

[0144] Compared with the support layer 500, the third conductive layer 503 and the fourth conductive layer 504 have higher strength and elastic modulus. By setting the third conductive layer 503 and the fourth conductive layer 504 in the end region, the elastic modulus of the composite current collector 50 in the end region can be improved, the risk of wrinkling of the positive electrode sheet 5 in the end region can be reduced, and the battery cell has a higher preparation yield.

[0145] In some embodiments, the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 at the first end is greater than or equal to the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 at the second end. The first end is an end along the width direction of the composite current collector 50 where the end region is far from the middle region, and the second end is an end along the width direction of the composite current collector 50 where the end region is close to the middle region.

[0146] The third conductive layer 503 and the fourth conductive layer 504 have a first end and a second end opposite each other along the width direction (e.g., the y direction in FIG8) of the composite current collector 50, wherein the first end is away from the central region relative to the second end.

[0147] As an example, as shown in Figure 8, the third conductive layer 503 and the fourth conductive layer 504 are right-angled triangles in the yoz plane, and the thickness of the third conductive layer 503 and the fourth conductive layer 504 is the largest at the first end and the thickness is 0 at the second end.

[0148] As an example, the third conductive layer 503 and the fourth conductive layer 504 are quarter-circles in the yoz plane, and the thickness of the third conductive layer 503 and the fourth conductive layer 504 is the largest at the first end and the thickness is 0 at the second end.

[0149] As an example, the composite current collector 50 can be prepared by the following steps: providing a support layer 500; cutting both ends of the support layer 500 in the width direction to obtain a support layer 500 with notches at both ends, wherein the notches can be triangular, arc or rectangular or other shapes; performing metal deposition treatment on the notches to obtain a third conductive layer 503 and a fourth conductive layer 504; performing metal deposition treatment on the middle region of the support layer 500 and the surface of the third conductive layer and the fourth conductive layer 504 to obtain a first conductive layer 501 and a second conductive layer 502.

[0150] As an example, the composite current collector 50 is prepared by the following steps: the support layer 500 is prepared by extrusion molding into a shape in which the thickness of the end region is less than that of the middle region, and then the support layer 500 is vapor-deposited on the surface of the support layer 500 to obtain the third conductive layer 503, the fourth conductive layer 504, the first conductive layer 501, and the second conductive layer 502.

[0151] When the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 at the first end is greater than the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 at the second end, it facilitates the deposition of the third conductive layer 503 and the fourth conductive layer 504 at the notch, reduces the number of bends, lowers the risk of less conductive layer being deposited at the bend positions, facilitates the preparation of the third conductive layer 503 and the fourth conductive layer 504, and facilitates obtaining a composite current collector 50 with a larger elastic modulus in the end region.

[0152] Figure 9 is a schematic diagram of a composite current collector according to an embodiment of this application. In some embodiments, for example, as shown in Figure 9, the third conductive layer 503 and / or the fourth conductive layer 504 are rectangular in shape.

[0153] The thickness of the third conductive layer 503 and / or the fourth conductive layer 504 at the first end is equal to the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 at the second end, and the third conductive layer 503 and the fourth conductive layer 504 are rectangular in shape in the yoz plane. In this way, the elastic modulus of the composite current collector 50 is more uniform and larger in the end region, which helps to reduce the risk of wrinkling of the composite current collector 50.

[0154] In the above embodiments, the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 at the first end is greater than or equal to the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 at the second end, which facilitates obtaining a composite current collector 50 with a larger elastic modulus in the end region.

[0155] In some embodiments, the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 gradually decreases along the direction from the end region to the middle region. This helps to reduce the difficulty of fabricating the third conductive layer 503 and / or the fourth conductive layer 504, and the end region of the composite current collector 50 has a larger elastic modulus.

[0156] Along the thickness direction of the composite current collector 50, the third conductive layer 503 and the fourth conductive layer 504 are spaced apart, and the third conductive layer 503 and the fourth conductive layer 504 can also be in at least partial contact.

[0157] For example, as shown in Figures 8 and 9, the third conductive layer 503 and the fourth conductive layer 504 are spaced apart along the thickness direction of the composite current collector 50. That is, along the thickness direction of the composite current collector, the end region includes the first conductive layer 501, the third conductive layer 503, the support layer 500, the fourth conductive layer 504, and the second conductive layer 502, which are sequentially arranged.

[0158] Figure 10 is a schematic diagram of a composite current collector according to an embodiment of the present application, Figure 11 is a schematic diagram of a composite current collector according to an embodiment of the present application, and Figure 12 is a schematic diagram of a composite current collector according to an embodiment of the present application. For example, as shown in Figures 10 to 12, along the thickness direction of the composite current collector, the third conductive layer 503 and the fourth conductive layer 504 are at least partially in contact.

[0159] In some embodiments, the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 at the first end is 0.5 μm to 3 μm.

[0160] For example, as shown in Figures 8 and 9, the thickness of the third conductive layer 503 at the first end is denoted as D3, and the thickness of the fourth conductive layer 504 at the first end is denoted as D4.

[0161] The third conductive layer 503 and the fourth conductive layer 504 can have the same thickness or different thicknesses.

[0162] As an example, as shown in Figures 8 and 9, the third conductive layer 503 and the fourth conductive layer 504 have the same thickness.

[0163] D3 can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.8μm, 2.0μm, 2.2μm, 2.5μm, 2.8μm, 2.9μm, 3.0μm or any value within the above range, and D4 can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.8μm, 2.0μm, 2.2μm, 2.5μm, 2.8μm, 2.9μm, 3.0μm or any value within the above range.

[0164] The reliability of a single battery cell under extreme conditions is related to the thickness of the third conductive layer 503 and the fourth conductive layer 504. For example, in the case of a nail penetration test on a single battery cell, the thicker the third conductive layer 503 and the fourth conductive layer 504, the longer the burrs on the third conductive layer 503 and the fourth conductive layer 504 caused by the nail penetration, the greater the risk of puncturing the separator, and consequently the greater the risk of short circuit caused by the overlap between the positive electrode (e.g., the aluminum foil of the positive electrode) and the negative electrode (e.g., the negative active material in the negative electrode), the lower the probability of passing the nail penetration test, which is detrimental to improving the reliability of the single battery cell.

[0165] When the thickness of the third conductive layer and / or the fourth conductive layer at the first end is greater than or equal to 0.5 μm, the third conductive layer 503 and / or the fourth conductive layer 504 having a certain thickness can effectively improve the elastic modulus of the end region of the composite current collector 50 and reduce the risk of wrinkling in the end region of the positive electrode 5. When the thickness of the third conductive layer and / or the fourth conductive layer at the first end is less than or equal to 3 μm, the risk of short circuit caused by the overlap of the positive and negative electrode sheets in extreme cases can be reduced. By setting the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 at the first end to be 0.5 μm to 3 μm, the fabrication efficiency and reliability of the battery cell can be balanced.

[0166] In some embodiments, the thickness of the third conductive layer 503 and / or the fourth conductive layer 504 is 0.8 μm to 1.5 μm. This allows for a further balance between the fabrication efficiency and reliability of the battery cells.

[0167] In some embodiments, the dimensions of the third conductive layer 503 and / or the fourth conductive layer 504 along the width direction of the composite current collector 50 are 0.05L0 to 0.12L0, where L0 is the dimension of the first conductive layer 501 and / or the second conductive layer 502 along the width direction of the composite current collector 50.

[0168] For example, as shown in Figures 8 and 9, along the width direction of the composite current collector 50, the dimension of the third conductive layer 503 is denoted as L1, and the dimension of the fourth conductive layer 504 is denoted as L2.

[0169] Along the width direction of the composite current collector 50, the third conductive layer 503 and the fourth conductive layer 504 may have the same size or different sizes.

[0170] As an example, as shown in Figures 8 and 9, along the width direction of the composite current collector 50, the third conductive layer 503 and the fourth conductive layer 504 have the same dimensions, and the first conductive layer 501 and the second conductive layer 502 have the same dimensions.

[0171] L1 can be 0.05L0, 0.06L0, 0.07L0, 0.08L0, 0.09L0, 0.1L0, 0.11L0, 0.12L0 or any value within the above range, and L2 can be 0.05L0, 0.06L0, 0.07L0, 0.08L0, 0.09L0, 0.1L0, 0.11L0, 0.12L0 or any value within the above range.

[0172] When the dimensions of the third conductive layer and / or the fourth conductive layer are greater than or equal to 5%L0, the end region of the composite current collector 50 has a certain size, which can effectively improve the elastic modulus of the end region of the composite current collector 50 and reduce the risk of wrinkling in the end region of the positive electrode 5. When the dimensions of the third conductive layer and / or the fourth conductive layer are less than or equal to 12%L0, the risk of short circuit caused by the overlap of the positive and negative electrode sheets in extreme cases can be reduced. By setting the dimensions of the third conductive layer 503 and / or the fourth conductive layer 504 to be 0.05L0 to 0.12L0 along the width direction of the composite current collector 50, both the fabrication efficiency and reliability of the battery cell can be taken into account.

[0173] In some embodiments, the dimensions of the third conductive layer 503 and / or the fourth conductive layer 504 are 5 mm to 12 mm along the width direction of the composite current collector 50.

[0174] Along the width direction of the composite current collector 50, the size L1 of the third conductive layer 503 can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm or any value within the above range; along the width direction of the composite current collector 50, the size L2 of the fourth conductive layer 504 can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm or any value within the above range.

[0175] By setting the dimensions of the third conductive layer 503 and / or the fourth conductive layer 504 to be 5mm to 12mm along the width direction of the composite current collector 50, the fabrication efficiency and reliability of the battery cell can be further balanced.

[0176] In some embodiments, 4500MPa≤G≤6000MPa.

[0177] In the above embodiments, by setting the third conductive layer 503 and the fourth conductive layer 504, the elastic modulus of the composite current collector 50 along the width direction is 4500MPa to 6000MPa. The composite current collector 50 has a large elastic modulus, the risk of wrinkling of the positive electrode sheet 5 is low, and the battery cell has a high preparation yield.

[0178] In some embodiments, 310mg / 1540.25mm 2 ≤A≤450mg / 1540.25mm 2 .

[0179] In the above embodiments, through the provision of the third conductive layer 503 and the fourth conductive layer 504, the composite current collector 50 has a large elastic modulus, and is equipped with a loading capacity of 310 mg / mm². 2With an active material concentration of ~450 mg / mm², the risk of wrinkling in the positive electrode sheet is relatively low, which can balance the preparation efficiency and volumetric energy density of the battery cell.

[0180] In some embodiments, the thickness of the first conductive layer 501 and / or the second conductive layer 502 is 0.8 μm to 1.2 μm, and the thickness of the support layer 500 is 6 μm to 10 μm.

[0181] As an example, the first conductive layer 501 and the second conductive layer 502 have the same thickness.

[0182] The thicknesses of the first conductive layer 501, the second conductive layer 502, and the support layer 500 can be measured in the following way: along the width direction of the composite current collector 50, the thicknesses of the first conductive layer 501, the second conductive layer 502, and the support layer 500 are measured at multiple locations, and the average value of the measured thicknesses is taken as the thickness of the first conductive layer 501, the second conductive layer 502, and the support layer 500.

[0183] Taking Figure 5 as an example, the thickness of the first conductive layer 501 can be denoted as D11, the thickness of the second conductive layer 502 can be denoted as D12, and the thickness of the support layer 500 can be denoted as D2. D11 can be 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm or any value within the above range, D12 can be 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm or any value within the above range, and D2 can be 6μm, 7μm, 8μm, 9μm, 10μm or any value within the above range.

[0184] By incorporating the third conductive layer 503 and the fourth conductive layer 504, the elastic modulus of the composite current collector 50 in the end region increases, reducing the risk of wrinkling. This allows for the combination of a thinner first conductive layer 501 and second conductive layer 502, as well as a thinner support layer 500, thereby further improving the volumetric energy density and reliability of the battery cell.

[0185] In some embodiments, along the thickness direction of the composite current collector 50, the conductive structure layer in the end region includes a first conductive layer 501 and a second conductive layer 502, and the conductive structure layer in the middle region includes a first conductive layer 501 and a second conductive layer 502.

[0186] In this embodiment, along the thickness direction of the composite current collector 50, there are a first conductive layer 501, a support layer 500, and a second conductive layer 502 arranged sequentially; the structure of the composite current collector is relatively simple and easy to manufacture; in addition, by setting the thickness of the support layer 500 or the first conductive layer 501 and the second conductive layer 502, the composite current collector 50 also has a lower risk of wrinkling.

[0187] The reliability of a single battery cell under extreme conditions is related to the thickness of the first conductive layer 501, the second conductive layer 502, and the support layer 500. For example, in the case of a needle penetration test on a single battery cell, the thicker the first conductive layer 501 and the second conductive layer 502, the longer the burrs on the first conductive layer 501 and the second conductive layer 502 caused by the needle penetration, the greater the risk of puncturing the separator, and consequently the greater the risk of short circuit caused by the overlap between the positive electrode (e.g., the aluminum foil in the positive electrode) and the negative electrode (e.g., the negative electrode active material in the negative electrode), reducing the probability of passing the needle penetration test and hindering the improvement of the battery cell's reliability. Conversely, the thicker the support layer 500, the lower the risk of puncturing the separator, the lower the risk of short circuit in the battery cell, and the higher the reliability of the battery cell. Therefore, a reasonable thickness of the first conductive layer 501, the second conductive layer 502, and the support layer 500 is beneficial for improving the reliability of the battery cell while reducing the risk of wrinkling in the composite current collector.

[0188] In some embodiments, the thickness of the first conductive layer 501 and / or the second conductive layer 502 is greater than 1 μm and less than or equal to 1.5 μm. This results in a lower risk of wrinkling in the composite current collector and a higher fabrication yield for the battery cell; simultaneously, the battery cell can also achieve both high energy density and high reliability.

[0189] The thickness of the first conductive layer 501 and / or the second conductive layer 502 can be 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm or any value within the above range.

[0190] In some embodiments, the thickness of the first conductive layer 501 and / or the second conductive layer 502 is 1.2 μm to 1.5 μm. This results in a larger thickness for the first conductive layer 501 and / or the second conductive layer 502, leading to a larger elastic modulus in the composite current collector, which helps reduce the risk of wrinkling in the composite current collector.

[0191] In some implementations, the thickness of the first conductive layer 501 and / or the second conductive layer 502 is 1.2 μm to 1.5 μm, and the thickness of the support layer 500 is 6 μm to 10 μm.

[0192] When the thickness of the first conductive layer 501 and / or the second conductive layer 502 is 1.2 μm to 1.5 μm, the composite current collector 50 has a relatively large elastic modulus along its width. By setting the thickness of the support layer 500 to 6 μm to 10 μm, the relatively small thickness of the support layer 500 is beneficial to further improving the volumetric energy density of the battery cell. In this way, the support layer 500 has a small thickness, and the first conductive layer 501 and the second conductive layer 502 have suitable thicknesses, which is beneficial to improving the elastic modulus of the composite current collector 50 and reducing the risk of short circuit caused by the overlap of the positive and negative electrode sheets in extreme cases. The battery cell achieves both high fabrication yield and high reliability.

[0193] In some embodiments, 3600MPa≤G≤5000MPa.

[0194] When the thickness of the first conductive layer 501 and / or the second conductive layer 502 is 1.2 μm to 1.5 μm, and the thickness of the support layer 500 is 6 μm to 10 μm, the elastic modulus of the composite current collector 50 along its width direction can be 3600 MPa to 5000 MPa. Thus, the composite current collector 50 has a large elastic modulus, the risk of wrinkling of the positive electrode sheet 5 is low, and the battery cell has a high fabrication yield.

[0195] In some embodiments, 280mg / 1540.25mm 2 ≤A≤390mg / 1540.25mm 2 .

[0196] When the thickness of the first conductive layer 501 and / or the second conductive layer 502 is 1.2 μm to 1.5 μm, and the thickness of the support layer 500 is 6 μm to 10 μm, the composite current collector 50 has a larger elastic modulus along the width direction, resulting in a lower risk of wrinkling. Therefore, it can be paired with 280mg / 1540.25mm... 2 ~390mg / 1540.25mm 2 The loading of active materials can improve the preparation yield of battery cells and further increase the volumetric energy density of battery cells.

[0197] In some embodiments, the thickness of the support layer 500 is 10 μm to 15 μm.

[0198] With a support layer thickness of 10μm to 15μm, the composite current collector 50 has a high elastic modulus, a low risk of electrode wrinkling, and a high fabrication yield for the battery cell.

[0199] In some embodiments, the thickness of the support layer 500 is 10 μm to 15 μm, and the thickness of the first conductive layer 501 and / or the second conductive layer 502 is 0.5 μm to 1 μm.

[0200] With the support layer 500 having a thickness of 10μm to 15μm, the composite current collector 50 has a high elastic modulus, which can be combined with a first conductive layer 501 and a second conductive layer 502 with a smaller thickness to improve the reliability of the battery cell while increasing the elastic modulus.

[0201] In the above embodiments, the support layer 500 has a large thickness and the first conductive layer and the second conductive layer have a small thickness. The composite current collector 50 has a high elastic modulus, and the risk of short circuit caused by the overlap of the positive and negative electrode sheets is low in extreme cases. The battery cell has both high fabrication yield and high reliability.

[0202] In some embodiments, 4000MPa≤G≤5000MPa.

[0203] When the thickness of the first conductive layer 501 and / or the second conductive layer 502 is 0.5 μm to 1 μm, and the thickness of the support layer 500 is 10 μm to 15 μm, the elastic modulus of the composite current collector 50 along its width direction can be 4000 MPa to 5000 MPa. Thus, the composite current collector 50 has a large elastic modulus, the risk of wrinkling of the positive electrode sheet 5 is low, and the battery cell has a high fabrication yield.

[0204] In some embodiments, 280mg / 1540.25mm 2 ≤A≤340mg / 1540.25mm 2 .

[0205] When the thickness of the first conductive layer 501 and / or the second conductive layer 502 is 0.5 μm to 1 μm, and the thickness of the support layer 500 is 10 μm to 15 μm, the composite current collector 50 has a large elastic modulus along the width direction, resulting in a lower risk of wrinkling. Therefore, it can be paired with 280mg / 1540.25mm... 2 ~340mg / 1540.25mm 2 The loading of active materials can improve the preparation yield of battery cells and further increase the volumetric energy density of battery cells.

[0206] In some embodiments, the positive electrode 5 is a positive electrode.

[0207] When the electrode is a positive electrode, A can be the loading of the positive electrode active material per unit area.

[0208] Figure 13 is a schematic diagram of a positive electrode sheet according to an embodiment of this application. In some embodiments, for example, as shown in conjunction with Figures 6 and 13, the positive electrode sheet further includes a positive electrode tab 602, which protrudes from the composite current collector 50 along the width direction of the composite current collector 50; the positive electrode sheet further includes an insulating layer 70, which is closer to the positive electrode tab 602 than the positive electrode film layer 60 along the width direction of the composite current collector 50.

[0209] The insulation layer 70 reduces the risk of short circuits caused by the overlap of the positive and negative electrode plates, which helps improve the reliability of the battery cell.

[0210] In some embodiments, the positive electrode film 60 includes a positive electrode active material, which includes a lithium phosphate.

[0211] Lithium phosphate has high structural stability, and lithium phosphate battery cells have better cycle performance and reliability. Furthermore, by setting the elastic modulus of the composite current collector 50, the positive electrode can be coated with more active material, and the battery cell also has a high volumetric energy density.

[0212] In some embodiments, lithium-containing phosphates include lithium iron phosphate.

[0213] In some embodiments, the lithium phosphate contains at least one of the following conditions:

[0214] The compacted density P1 of lithium phosphate powder at 3T satisfies: 2.35 g / cm³ 3 ≤P1≤2.65g / cm 3 ;

[0215] The discharge capacity Q0 of lithium phosphate at 0.1C satisfies: 157.0 mAh / g ≤ Q0 ≤ 160.0 mAh / g;

[0216] The initial coulombic efficiency K of lithium phosphate satisfies: 99% ≤ K ≤ 100%.

[0217] P1 can be 2.35 g / cm³ 3 2.38g / cm 3 2.4g / cm 3 2.45g / cm 3 2.5g / cm 3 2.55g / cm 3 2.6g / cm 3 2.65g / cm 3Or any value within the above range, Q0 can be 157.0mAh / g, 157.5mAh / g, 158mAh / g, 158.5mAh / g, 159mAh / g, 159.5mAh / g, 160mAh / g or any value within the above range, K can be 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.8%, 99.9%, 100% or any value within the above range.

[0218] The compaction density of lithium phosphate powder meets the above range, the positive electrode sheet can have a high compaction density, and the battery cell has a high energy density; the discharge specific capacity of lithium phosphate at 0.1C meets the above range, and the battery cell has a high energy density; the initial coulombic efficiency of lithium phosphate meets the above range, and the battery cell has a high capacity.

[0219] In some embodiments, the lithium phosphate contains at least one of the following conditions:

[0220] The water content B of lithium phosphate satisfies: 0 ≤ B ≤ 500 ppm;

[0221] The volume average particle size Dv50 of lithium phosphate satisfies: 0.5μm≤Dv50≤3μm;

[0222] The particle size distribution span of lithium phosphates satisfies: (Dv90-Dv10) / Dv50≤3.5.

[0223] The water content B of the lithium phosphate can be 10ppm, 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 100ppm, 150ppm, 200ppm, 250ppm, 300ppm, 350ppm, 400ppm, 450ppm, 500ppm or any value within the above range.

[0224] The lower the water content of the lithium phosphate, the less stress is experienced in the end region of the composite current collector along the width direction of the composite current collector away from the end region during the drying process of the positive electrode slurry. This is beneficial to reducing the wrinkling degree of the positive electrode 5 during the drying process and improving the yield of the battery cell. In this embodiment, by setting 0≤B≤500ppm, the wrinkling degree of the positive electrode 5 during the drying process can be reduced, which is beneficial to improving the yield of the battery cell.

[0225] Dv50 can refer to the particle size corresponding to 50% of the cumulative particle size distribution number of a sample, which means that 50% of the particles are smaller than Dv50.

[0226] The volume average particle size Dv50 of lithium phosphate can be 0.5μm, 0.8μm, 1μm, 1.2μm, 1.5μm, 1.7μm, 1.9μm, 2μm, 2.2μm, 2.5μm, 2.8μm, 3μm or any value within the above range.

[0227] Large-diameter lithium phosphate particles exhibit less capillary action compared to small-diameter lithium phosphate particles. Within a certain range, the larger the volume average particle size of the lithium phosphate, the less stress is experienced at the end region of the composite current collector along the width direction of the composite current collector during the drying process of the positive electrode slurry. This helps reduce the wrinkling degree of the positive electrode 5 during the drying process and improves the yield of the battery cell. In this embodiment, by setting 0.5μm≤Dv50≤3μm, the wrinkling degree of the positive electrode 5 during the drying process can be reduced, which is beneficial to improving the yield of the battery cell.

[0228] Dv90 can refer to the particle size corresponding to 90% of the cumulative particle size distribution number of a sample, which means that 90% of the particles are smaller than Dv90.

[0229] Dv10 can refer to the particle size corresponding to a sample when the cumulative particle size distribution number reaches 10%, which means that 10% of the particles are smaller than Dv10.

[0230] (Dv90-Dv10) / Dv50 can be 3.5, 3.43, 3.31, 3.25, 3.11, 2.98, 2.85, 2.77, 2.63, 2.6, 2.55, 2.45, 2.33, 2.25, 2.1, 2.03 or any value within the above range.

[0231] The particle size distribution span (Dv90-Dv10) / Dv50 represents the degree of concentration of the particle size distribution; the smaller the value, the more concentrated the particle size distribution. A more concentrated particle size distribution results in less tortuous evaporation paths for the solvent in the positive electrode slurry during drying, reducing stress on the end region of the composite current collector and minimizing wrinkling of the positive electrode 5 during drying, thus improving the yield of the battery cell. In this embodiment, by setting (Dv90-Dv10) / Dv50 ≤ 3.5, the wrinkling of the positive electrode 5 during drying can be reduced, further improving the yield of the battery cell.

[0232] In some embodiments, the lithium phosphate contains at least one of the following conditions:

[0233] The volume average particle size Dv50 of lithium phosphate satisfies: 1μm≤Dv50≤3μm;

[0234] The particle size distribution span of lithium phosphates satisfies: (Dv90-Dv10) / Dv50≤2.6.

[0235] The above technical solution is conducive to further reducing the wrinkling degree of the electrode sheet during the drying process and improving the preparation yield of the battery cell.

[0236] In some embodiments, the lithium phosphate contains at least one of the following conditions:

[0237] The volume average particle size Dv50 of lithium phosphate satisfies: 2μm≤Dv50≤3μm;

[0238] The particle size distribution span of lithium phosphates satisfies: (Dv90-Dv10) / Dv50≤2.1.

[0239] The above technical solution is conducive to further reducing the wrinkling degree of the electrode sheet during the drying process and improving the preparation yield of the battery cell.

[0240] In some embodiments, only the volume average particle size or the particle size distribution span of the lithium phosphate can be set, without special design of the composite current collector structure, to reduce the risk of wrinkling of the composite current collector during the drying process of the slurry. As an example, the volume average particle size Dv50 of the lithium phosphate can be 1.0 μm to 3 μm, optionally 2 μm to 3 μm. As another example, the particle size distribution span of the lithium phosphate satisfies: (Dv90-Dv10) / Dv50≤3.5, optionally (Dv90-Dv10) / Dv50≤2.6.

[0241] In some embodiments, the compaction density P2 of the positive electrode sheet satisfies: 2.55 g / cm³ 3 ≤P2≤2.8g / cm 3 In this way, the positive electrode sheet has a high compaction density, and the battery cell has a high energy density.

[0242] P2 can be 2.55 g / cm³ 3 2.6g / cm 3 2.65g / cm 3 2.7g / cm 3 2.75g / cm 3 2.8g / cm 3 Or any value within the above range.

[0243] In some embodiments, the volumetric energy density of a single battery cell is greater than or equal to 400Wh / L.

[0244] The volumetric energy density of a single battery cell can be 400Wh / L, 410Wh / L, 420Wh / L, 430Wh / L, 450Wh / L, or any value within the above range.

[0245] In the above embodiments, the volumetric energy density of the battery cell is greater than or equal to 400Wh / L, so that the battery cell can achieve both high preparation yield and large volumetric energy density.

[0246] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. As an example, as shown in Figure 3, the battery cell is a square battery cell.

[0247] In some embodiments, the battery cell 3 includes a housing 31, an end cap assembly 32, and an electrode assembly 33 disposed in the housing 31.

[0248] The electrode assembly 33 can be manufactured from a positive electrode, a negative electrode, and a separator through a winding process or a stacking process. The electrode assembly 33 may include an electrode assembly body 330 and a tab 331 extending from the electrode assembly body 330.

[0249] The tab portion 331 can be formed by integrating multiple tabs of the positive electrode or the negative electrode, and the electrode assembly body 330 can include the area of ​​the positive electrode coated with a positive electrode film layer, the separator, and the area of ​​the negative electrode coated with a positive electrode film layer.

[0250] The end cap assembly 32 includes electrode terminals 322, as shown in FIG3. The end cap assembly 32 includes two electrode terminals 322, one of which is a positive electrode terminal and the other is a negative electrode terminal.

[0251] The battery cell 3 also includes a connecting member 34 for connecting the tab 331 and the electrode terminal 322 of the electrode assembly 33. For example, one connecting member 34 is used to connect the tab of the positive electrode and the positive electrode terminal, and another connecting member 34 is used to connect the tab of the negative electrode and the negative electrode terminal.

[0252] [Positive electrode plate]

[0253] The positive electrode includes a composite current collector and a positive electrode film layer disposed on at least one surface of the composite current collector.

[0254] Composite current collectors can be formed by forming metallic materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on a polymer substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0255] In some embodiments, the positive electrode film layer includes a positive electrode active material. The positive electrode active material may be any positive electrode active material known in the art for use in batteries. For example, the positive electrode active material is a lithium phosphate with an olivine structure, a lithium transition metal oxide, a spinel-structured material, etc. The general formula for lithium phosphates with an olivine structure may be Li... a A x Mn 1-y B y P 1-z C z O 4-n D n Wherein, 0 < a ≤ 1.1, 0.001 ≤ x ≤ 0.1, 0.001 ≤ y < 0.5, 0.001 ≤ z ≤ 0.1, 0.001 ≤ n ≤ 0.1, A includes one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W, B includes one or more of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge, C includes one or more of B, S, Si, and N, and D includes one or more of S, F, Cl, and Br. Lithium-containing phosphates with an olivine structure can include at least one of lithium iron phosphate, lithium manganese phosphate, and lithium manganese iron phosphate. Lithium transition metal oxides can include ternary materials, lithium-rich manganese-based materials, etc. Spinel-structured materials can include lithium manganese oxide, etc.

[0256] In some embodiments, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.1 Al 0.05One or more of O2 and its modified compounds.

[0257] During the charging and discharging process of a battery, Li undergoes insertion / extraction and consumption. The molar content of Li in the positive electrode active material varies depending on the discharge state. In the examples of positive electrode active materials listed in this application, the molar content of Li refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar content of Li changes when the positive electrode active material is applied to the battery system. Similarly, the molar content of O in the examples of positive electrode active materials listed in this application is only an ideal value. Lattice oxygen release causes changes in the molar content of O, and the actual molar content of O will fluctuate.

[0258] In some embodiments, the positive electrode film layer further includes a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0259] In some embodiments, the positive electrode film layer further includes a conductive agent. The conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0260] In one embodiment, the positive electrode sheet can be prepared by forming a positive electrode slurry using the components described above. For example, the positive electrode active material, conductive agent, binder, and any other components are dispersed in a solvent (e.g., NMP) to form the positive electrode slurry. The positive electrode slurry is then coated onto a composite current collector, and after drying, cold pressing, and other processes, the positive electrode sheet is obtained.

[0261] [Negative electrode plate]

[0262] The negative electrode includes a negative current collector and a positive electrode film layer disposed on the negative current collector.

[0263] The negative electrode current collector can be a metal material such as copper foil, or it can be a composite current collector. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0264] The positive electrode film layer includes a negative electrode active material. The negative electrode active material can be any negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from one or more of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0265] The positive electrode film layer may also optionally include a binder. As an example, the binder may include one or more of the following: styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0266] The positive electrode film may optionally include a conductive agent. The conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0267] In one embodiment, the negative electrode sheet can be prepared by forming a negative electrode slurry using the components described above. For example, the negative electrode active material, conductive agent, binder, and any other components are dispersed in a solvent (e.g., deionized water) to form the negative electrode slurry. The negative electrode slurry is then coated onto a composite current collector, and after drying, cold pressing, and other processes, the negative electrode sheet is obtained.

[0268] [Electrolytes]

[0269] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or entirely solid.

[0270] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0271] For lithium-ion battery cells or lithium metal battery cells, the electrolyte salt may include one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0272] For lithium-ion battery cells or lithium metal battery cells, the solvent may include one or more of the following: ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0273] For sodium-ion battery cells or sodium metal battery cells, the electrolyte salt may include at least one of NaPF6, NaBF4, NaN(SO2F)2, NaClO4, NaAsF6, NaB(C2O4)2, NaBF2(C2O4), NaN(SO2RF)2, and NaN(SO2F)(SO2RF), where RF includes C b F 2b+1 b is an integer from 1 to 10; optionally, the electrolyte salt includes at least one of NaPF6, NaN(SO2F)2, and NaBF2(C2O4); optionally, b is an integer from 1 to 3; optionally, RF includes at least one of CF3, C2F5, and CF2CF2CF3.

[0274] For sodium-ion battery cells or sodium metal battery cells, the solvent may include at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, diethyl sulfone, 1,3-dioxolane, tetrahydrofuran, ethylene glycol dimethyl ether, and acetonitrile; optionally, the solvent may include at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, and butyl carbonate.

[0275] The electrolyte may also optionally include negative electrode film-forming additives, positive electrode film-forming additives, and performance additives that can improve certain battery performance, such as performance additives that improve battery overcharge performance, battery high temperature or low temperature performance, etc.

[0276] [Isolation Component]

[0277] The separator is used to separate the positive electrode and the negative electrode. This application does not impose any particular limitation on the type of separator. In some embodiments, the separator is a separator membrane, wherein any known porous separator membrane with good chemical and mechanical stability can be selected.

[0278] The material of the separator can be selected from one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film; there are no particular restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different; there are no particular restrictions.

[0279] Positive electrode, negative electrode and separator can be made into electrode assembly by winding process.

[0280] [Battery Device]

[0281] This application provides a battery device including the battery cells described in the above embodiments. The battery device can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or mixed via a busbar.

[0282] In some embodiments, the battery device may be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0283] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0284] In some embodiments, the battery device may be located within an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0285] In some embodiments, the battery device 10 may further include other components. For example, the battery device 10 may further include a busbar component, which can be used to realize electrical connections between multiple battery cells 3, such as in parallel, series, or mixed connections. Specifically, the busbar component can realize electrical connections between battery cells 3 by connecting to the electrode terminals of the battery cells 3; or, the busbar component can also realize electrical connections between battery cells 3 by connecting to other components of the battery cells 3. The busbar component can be fixed to corresponding components of the battery cells 3 by welding, for example, by welding to electrode terminals, sealing structures, or housings, etc., and the embodiments of this application are not limited thereto.

[0286] The battery cells 3 can be directly assembled into the battery device 10, or they can be first assembled into battery modules, and then multiple battery modules can be assembled into the battery device 10.

[0287] [Electrical Equipment]

[0288] This application provides an electrical device including the battery device described in the above embodiments.

[0289] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical equipment.

[0290] As an example, the electrical equipment is a rail transport vehicle, such as a high-speed rail, a train, or a freight rail transport vehicle, and the battery device is installed on the aforementioned electrical equipment.

[0291] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0292] [Example]

[0293] Example 1

[0294] In Example 1, the structure of the positive electrode sheet is shown in Figures 6 and 7, and the structure of the composite current collector in the positive electrode sheet is shown in Figures 4 and 5. In the positive electrode sheet, the composite current collector includes a support layer and a first conductive layer and a second conductive layer disposed on both sides of the support layer. The support layer is made of PET, and the first and second conductive layers are made of aluminum. The thickness D2 of the support layer is 8 μm, the thickness D11 of the first conductive layer is 1.2 μm, and the thickness D12 of the second conductive layer is 1.2 μm. Along the width direction of the composite current collector, the elastic modulus G of the composite current collector is 4127 MPa, where the width direction of the composite current collector is the direction in which the positive electrode tab protrudes from the composite current collector.

[0295] A positive electrode film layer is disposed on both sides of the composite current collector along its thickness direction. The positive electrode film layer includes a positive electrode active material, which is lithium iron phosphate. The volume average particle size (Dv50) of the lithium iron phosphate is 1.5 μm. The thickness of the positive electrode sheet is 178 μm, and the coating weight (A) per unit area of ​​the positive electrode film layer is 330 mg / 1540.25 mm. 2 .

[0296] The negative electrode sheet includes a negative current collector copper foil and negative and positive electrode film layers disposed on both sides of the copper foil. The negative and positive electrode film layers include graphite, the negative electrode active material. The thickness of the negative electrode sheet is 130 μm, and the coating weight per unit area of ​​the negative electrode sheet is 150 mg / 1540.25 mm. 2 .

[0297] Example 2

[0298] The difference between Example 2 and Example 1 is that the thicknesses of the support layer, the first conductive layer and the second conductive layer in the positive electrode sheet are different.

[0299] In Example 2, the thickness D2 of the support layer is 10 μm, the thickness D11 of the first conductive layer is 1 μm, the thickness D12 of the second conductive layer is 1 μm, and the elastic modulus G of the composite current collector is 4452 MPa along the width direction; the coating weight A per unit area of ​​the positive electrode film is 310 mg / 1540.25 mm. 2 .

[0300] Example 3

[0301] The difference between Example 3 and Example 1 is that the structure of the composite current collector in the positive electrode is different.

[0302] The structure of the composite current collector in Example 3 can be seen in Figure 9. Along the thickness direction of the composite current collector, the middle region of the composite current collector includes a first conductive layer, a support layer, and a second conductive layer arranged sequentially, and the end region of the composite current collector includes a first conductive layer, a third conductive layer, a support layer, a fourth conductive layer, and a second conductive layer arranged sequentially. The third conductive layer and the fourth conductive layer have the same structure.

[0303] The thickness of the support layer D2 is 8 μm, the thickness of the first conductive layer D11 is 1 μm, the thickness of the second conductive layer D12 is 1 μm, and the thicknesses of the third conductive layer D3 and the fourth conductive layer D4 are both 1 μm. Along the width direction of the current collector, the dimensions of the third conductive layer L1 and the fourth conductive layer L2 are both 15 mm, and L0 is 200 mm. Along the width direction of the composite current collector, the elastic modulus G of the composite current collector is 5090 MPa, and the coating weight per unit area A of the positive electrode film is 380 mg / 1540.25 mm. 2 .

[0304] Examples 4-5

[0305] The difference between Examples 4-5 and Example 3 is that the thicknesses of the third and fourth conductive layers are different.

[0306] Examples 6-8

[0307] The difference between Examples 6-8 and Example 3 is that the dimensions L1 of the third conductive layer and L2 of the fourth conductive layer are different along the width direction of the current collector.

[0308] Examples 9-10

[0309] The difference between Examples 9-10 and Example 3 is that the volume average particle size of lithium iron phosphate is different.

[0310] Comparative Example 1

[0311] Comparative Example 1

[0312] The difference between Comparative Example 1 and Example 1 is that the thicknesses of the support layer, the first conductive layer and the second conductive layer in the positive electrode sheet are different.

[0313] In Comparative Example 1, the thickness D11 of the first conductive layer is 1 μm, the thickness D12 of the second conductive layer is 1 μm, the thickness of the support layer is 8 μm, and the elastic modulus G of the composite current collector is 3474 MPa along the width direction; the coating weight A per unit area of ​​the positive electrode film is 256 mg / 1540.25 mm. 2 .

[0314] The composite current collectors in Examples 1-10 and Comparative Example 1 were tested to observe whether wrinkling occurred after the positive electrode slurry was coated on the surface of the composite current collector and dried. Subsequently, battery cells were fabricated using the positive electrode sheets from Examples 1-10 and Comparative Example 1, and a needle penetration test was performed on the battery cells to observe their pass rate.

[0315] In the embodiments, the second conductive layer and the first conductive layer have the same structure, and the fourth conductive layer and the third conductive layer have the same structure. Table 1 only shows the thickness of the first conductive layer, the thickness of the third conductive layer, and the dimensions of the third conductive layer along the width direction of the composite current collector.

[0316] In Tables 1 and 2, D2 represents the thickness of the support layer, D11 represents the thickness of the first conductive layer, D3 represents the thickness of the third conductive layer, L1 represents the dimension of the third conductive layer along the width of the electrode, L1 / L0 represents the ratio of the third conductive layer to the first conductive layer along the width of the electrode, Dv50 represents the volume average particle size of lithium iron phosphate, A represents the maximum loading of the positive electrode film, G represents the elastic modulus of the composite current collector, and whether or not wrinkling is present indicates that the loading of the positive electrode film exceeds 256 mg / 1540.25 mm. 2 The wrinkling of the composite current collector after drying the positive electrode slurry.

[0317] Table 1. Specific parameters of Examples 1-10 and Comparative Example 1

[0318] Table 2 shows the test results of Examples 1-10 and Comparative Example 1.

[0319] As shown in Examples 1-10 and Comparative Example 1, the thickness of the support layer is greater than 8 μm and / or the thickness of the conductive structure layer in the end region is greater than 2 μm, and the loading of the positive electrode film layer exceeds 256 mg / 1540.25 mm. 2 After the positive electrode slurry was dried, the composite current collector was not wrinkled.

[0320] As shown in Examples 1-10 and Comparative Example 1, setting the elastic modulus in the width direction of the composite current collector to be greater than or equal to 3500 MPa is beneficial to increasing the maximum loading of the positive electrode film layer on the surface of the composite current collector and reducing the risk of wrinkling of the composite current collector after drying the positive electrode slurry.

[0321] In Comparative Example 1, the maximum loading of the positive electrode film layer on the surface of the composite current collector was 256 mg / 1540.25 mm. 2 At a concentration exceeding 256mg / 1540.25mm 2 Subsequently, during the drying process of the positive electrode slurry, wrinkling occurred in the composite current collector. In Examples 1-10, the maximum loading of the positive electrode film layer on the surface of the composite current collector all exceeded 256 mg / 1540.25 mm. 2 During the drying process of the positive electrode slurry, the composite current collector did not wrinkle.

[0322] As shown in Example 1, the thicknesses of the first and second conductive layers are set to 1.2 μm to 1.5 μm, the thickness of the support layer is 6 μm to 10 μm, and the elastic modulus of the composite current collector is 3600 MPa to 5000 MPa. The composite current collector is not prone to wrinkling. In addition, the loading of the positive electrode film layer can be set to 280 mg / mm². 2 ~390mg / mm 2This can improve the loading capacity while maintaining the preparation efficiency, thus giving the battery cell a larger energy density.

[0323] As shown in Example 2, the thicknesses of the first and second conductive layers are set to 0.5 μm to 1 μm, the thickness of the support layer is set to 10 μm to 15 μm, and the elastic modulus of the composite current collector is set to 4000 MPa to 5000 MPa. The composite current collector is less prone to wrinkling. In addition, the loading of the positive electrode film layer can be set to 280 mg / mm². 2 ~340mg / mm 2 This can improve the loading capacity while maintaining the preparation efficiency, thus giving the battery cell a larger energy density.

[0324] As shown in Examples 3-8, by setting a third and fourth conductive layer, the elastic modulus of the composite current collector can be improved, and a positive electrode film layer with greater weight can be loaded. As shown in Examples 3-5, the thickness of the first and second conductive layers is set to 0.8 μm to 1.2 μm, the thickness of the support layer is set to 6 μm to 10 μm, and the thickness of the third and fourth conductive layers at the first end is set to 0.5 μm to 3 μm. The composite current collector has a large elastic modulus, can load more active material, and does not wrinkle. As shown in Examples 6-8, along the width direction of the composite current collector, the size of the third and fourth conductive layers is 0.05L0 to 0.12L0. The battery cell achieves both good preparation efficiency and a large loading capacity, and all can pass the nail penetration test. As shown in Example 8, when the size of the third and fourth conductive layers exceeds 0.12L0, although the battery cell can pass the nail penetration test without ignition or explosion, one out of 20 battery cell samples showed smoke.

[0325] As shown in Examples 1 and 9-10, increasing the volume average particle size (Dv50) of lithium iron phosphate is beneficial for increasing coating weight and also helps reduce the risk of wrinkling of the positive electrode sheet. By setting the volume average particle size of lithium iron phosphate to 0.5 μm to 3 μm, the risk of wrinkling of the positive electrode sheet is low.

[0326] Examples 11-13

[0327] In Examples 11-13, the structure of the positive electrode is the same as in Example 2, the thickness of the support layer is 10 μm, the thickness of the first conductive layer and the second conductive layer are both 1 μm, and the coating weight A of the positive electrode film is 300 mg / 1540.25 mm. 2 .

[0328] The difference between Examples 11-13 is that the properties of the positive electrode active material are different.

[0329] Example 14

[0330] The difference between Example 14 and Example 11 is that the loading amount of the positive electrode film is different.

[0331] Example 15

[0332] The difference between Example 15 and Example 12 is that the loading amount of the positive electrode film is different.

[0333] Example 16

[0334] The difference between Example 16 and Example 15 lies in the structure of the composite current collector and the loading of the positive electrode film layer. Specifically, the structure of the composite current collector in Example 16 is the same as that in Example 3.

[0335] In Examples 11-16, the positive electrode active material was fabricated into positive electrode sheets and battery cells, and the relevant parameters of the positive electrode sheets and battery cells were tested. Specific test parameters for Examples 11-16 are shown in Table 3. In Table 3, P1 is the powder compaction density of the positive electrode active material at 3T, Q0 is the discharge specific capacity of the positive electrode active material at 0.1C, K is the initial coulombic efficiency of the positive electrode active material, A is the loading of the positive electrode film, P2 is the compaction density of the positive electrode sheet, Q1 is the 1 / 3C discharge capacity of the battery cell, and VED is the volumetric energy density of the battery cell.

[0336] Table 3 Test parameters for Examples 11-16

[0337] As shown in Examples 11-13, increasing the powder compaction density, discharge specific capacity, and initial coulombic efficiency of the positive electrode active material is beneficial for improving the compaction density of the positive electrode sheet, the discharge capacity of the battery cell, and the volumetric energy density. Furthermore, when the powder compaction density of the positive electrode active material is greater than 2.37 g / cm³... 3 With a discharge capacity greater than 154.3 mAh / g and an initial coulombic efficiency greater than 97.5%, the volumetric energy density of the battery cell is greater than 400 Wh / L. In conjunction with Examples 12 and 14, and Examples 13 and 15-16, increasing the loading A of the positive electrode film layer is beneficial for further improving the volumetric energy density of the battery cell.

[0338] The above describes the settings of each embodiment and comparative example. The following describes the preparation methods of battery cells and coin cells.

[0339] Preparation method of battery cell:

[0340] (1) Preparation of positive electrode sheet

[0341] PET raw material is loaded into an extrusion mold and the initial structure of the support layer is obtained by extrusion molding. Then, the initial structure is adjusted by directional stretching to obtain the support layer.

[0342] Aluminum metal material is vapor-deposited on the surface of the support layer to prepare a conductive structure layer (e.g., a first conductive layer and a second conductive layer, or a first conductive layer, a second conductive layer, a third conductive layer and a fourth conductive layer) to obtain a composite current collector;

[0343] Lithium iron phosphate, acetylene black, and polyvinylidene fluoride (PVDF) were uniformly mixed at a mass ratio of 8:1:1, and then N-methylpyrrolidone was added for dispersion. The solid content of the slurry was controlled at 45%–70%, and the viscosity was 5000 mPa·s–25000 mPa·s. The slurry was coated on both sides of the composite current collector. After coating, the electrode was dried and then rolled and die-cut to obtain the positive electrode.

[0344] It should be noted that in the preparation process of the composite current collector in Examples 3-10, a support layer of the corresponding shape is obtained by changing the extrusion die head of the extrusion mold, and then aluminum metal is vapor-deposited on the surface of the support layer to obtain the first conductive layer, the second conductive layer, the third conductive layer and the fourth conductive layer.

[0345] (2) Preparation of negative electrode sheet

[0346] Graphite, conductive carbon, and sodium polyacrylate are mixed uniformly in a mass ratio of 95:2:3. Deionized water is added and the mixture is evenly dispersed to obtain a homogeneous slurry. The slurry is then evenly coated onto copper foil and dried. Finally, the negative electrode sheet is obtained by rolling and die cutting.

[0347] (3) Isolation components

[0348] The separator is a polyethylene film with a PVDF coating.

[0349] (4) Electrolyte

[0350] An electrolyte was prepared by mixing 13 wt% lithium hexafluorophosphate, 33 wt% ethylene carbonate, 28 wt% dimethyl carbonate, 24 wt% ethyl methyl carbonate, and 2 wt% ethylene sulfate.

[0351] (5) Preparation of battery cells

[0352] By placing the electrodes in the order of "separator-negative electrode-separator-positive electrode", a wound electrode assembly is obtained. The electrode assembly is then installed into the housing, and after processes such as liquid injection and formation, a battery cell is obtained.

[0353] Methods for manufacturing button cells:

[0354] (1) Preparation of positive electrode sheet: Lithium iron phosphate, acetylene black and polyvinylidene fluoride (PVDF) are mixed uniformly in a mass ratio of 8:1:1, and then N-methylpyrrolidone is added for dispersion. The solid content of the slurry is controlled at 45% to 70%, and the viscosity is 5000 mPa·s to 25000 mPa·s. The slurry is coated on both sides of the composite current collector. After coating, the electrode sheet is dried and then rolled and then die-cut to obtain the positive electrode sheet.

[0355] (2) Preparation of negative electrode sheet: Lithium sheet is used as negative electrode sheet;

[0356] (3) Assembly: Assemble the positive electrode and lithium sheet into a button cell.

[0357] The following is a brief description of the testing methods for the physicochemical and performance parameters involved in the embodiments of this application. It should be understood that the following testing methods are only examples, and other testing methods known in the art can also be used for testing.

[0358] (1) Test method for coating weight

[0359] As an example, a single battery cell is disassembled to obtain electrode sheets, which are then cut to a specific size as samples. The positive electrode film layer on the sample is scraped off to obtain positive electrode film powder and the remaining composite current collector. The mass of the positive electrode film powder is then weighed. The coating weight per unit area = mass of positive electrode film powder / area of ​​the sample.

[0360] As another example, during the preparation process, a balance (e.g., Sartorius BSA124S electronic balance) is used to measure the mass of a composite current collector with a specific area and the mass of a composite current collector with the same area coated with a positive electrode film. The coating amount per unit area is calculated based on the difference in mass between the two and the area.

[0361] (2) Test method for elastic modulus

[0362] The composite current collector was tested using a tensile-compression testing machine to measure the stress-strain curve during the tensile process. The standard used for the tensile test was ISO 1924-1. The composite current collector was cut into rectangular strips of 70 mm × 7.5 mm. Before the tensile test, the strips were dried in an oven for 24 hours. The effective length of the strip was 50 mm, and the tensile rate was 1 mm / min.

[0363] Elastic modulus G = stress / strain.

[0364] (3) Thickness measurement method

[0365] The composite current collector was observed using a scanning electron microscope (SEM), and the thicknesses of the support layer, the first conductive layer, the second conductive layer, the third conductive layer, and the fourth conductive layer in the composite current collector were measured.

[0366] (4) Test method for water content of lithium phosphate

[0367] As an example, the water content of lithium phosphates is tested using GB / T-6283-2008.

[0368] (5) Test method for volume average particle size of lithium phosphate

[0369] As an example, the volume average particle size of the material can be tested using a Malvern 2000 (MasterSizer 2000) laser particle size analyzer, referring to GB / T19077-2016 / ISO 13320:2009. Specifically, take an appropriate amount of the sample to be tested (the sample concentration should be 8%–12% opacity), add 20 mL of anhydrous ethanol, and sonicate for 5 min (53 kHz / 120 W) to ensure complete dispersion. Then, measure the sample according to the GB / T19077-2016 / ISO13320:2009 standard.

[0370] As another example, scanning electron microscopy (SEM) was used to observe the positive electrode film. The number and size of lithium iron phosphate particles were counted in a specific area (e.g., 30 μm × 30 μm). The average size of the observed particles was taken as a reference for the volume average particle size.

[0371] (6) Test of powder compaction density

[0372] Lithium iron phosphate powder was placed into the sample cavity of the test equipment, and the powder was compacted under a pressure of 3T. The height H of the sample after compaction under this pressure was recorded.

[0373] The compacted density of the powder is P1 = m / (H×S), where m is the mass of the weighed lithium iron phosphate powder, S is the bottom area of ​​the mold, and H is the height of the compacted sample.

[0374] (7) Testing of the 0.1C discharge specific capacity and initial coulombic efficiency of the positive electrode active material

[0375] Charge the coin cell to 3.65V at 0.1C, then charge it at 3.65V under constant voltage until the current is ≤0.05mA. Let it stand for 2 minutes. The charging capacity at this time is recorded as C0. Then discharge it to 2.5V at 0.1C. The discharge capacity at this time is the initial specific capacity, recorded as Q0. The initial coulombic efficiency is Q0 / C0×100%.

[0376] (8) Testing the compaction density of the electrode sheet

[0377] Take an electrode with area s, measure its thickness as h1, and its weight as m1; take a composite current collector with the same area, its thickness as h2, and its weight as m2; the compaction density of the electrode is (m1-m2) / [s×(h1-h2)], in g / cm³. 3 .

[0378] As an example, a composite current collector can be obtained by removing the coating (e.g., positive electrode film) on the electrode.

[0379] (9) Testing of the volumetric energy density of a single battery cell

[0380] At room temperature (25℃±2℃), the battery cells were discharged to 2V using a constant current discharge (1 / 3C rate), then left to stand for 30 minutes. They were then charged to 3.65V using a constant current 1 / 3C rate, and continued to be charged at a constant voltage until the charging current was less than 0.05C. After standing for 30 minutes, the cells were discharged to 2.5V using a constant current 1 / 3C rate, and left to stand for 30 minutes. The discharge energy E (in Wh) of the battery cells was recorded.

[0381] After repeating the process three times, take the average of the three discharge energies E, divide it by the volume V of the battery cell, and then the volumetric energy density VED = E. average / V, the unit is Wh / L.

[0382] (10) Needle prick test

[0383] Twenty battery cells were tested using the standard TJ / JW126—2020, and the number of battery cells that passed the test was recorded.

[0384] Specifically, discharge the battery to the termination voltage at rated current at room temperature (e.g., 25°C), then charge it according to the manufacturer's charging method. Next, using a high-temperature resistant steel needle with a diameter of 5mm to 8mm and a cone angle of 45° to 60° at the tip, the needle should have a smooth surface free of rust, oxide layer, and oil. Pierce the needle at a speed of 25mm / s ± 5mm / s, perpendicular to the thickness of the electrode assembly. The penetration point should be close to the geometric center of the pierced surface. Finally, leave the needle inside the battery cell and observe for 1 hour. Observe for any signs of fire or explosion within 1 hour. If fire or explosion occurs, the needle penetration test is considered a failure.

[0385] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell, characterized by, include: A positive electrode tab including a composite current collector and a positive electrode film layer disposed on at least one side surface of the composite current collector, the positive electrode film layer having a loading amount A greater than 256 mg / 1540.25 mm 2 , the composite current collector including a support layer and a conductive structure layer disposed on both side surfaces of the support layer; The composite current collector satisfies at least one of the following conditions: The thickness of the support layer is greater than 8 μm; Along the width direction of the composite current collector, the composite current collector includes a central region and an end region, the end regions are located at both ends of the central region, and the total thickness of the conductive structure layer in the end regions is greater than 2 μm.

2. The battery cell of claim 1, wherein, Along the width direction of the composite current collector, the elastic modulus G of the composite current collector satisfies: 3500MPa≤G≤9000MPa.

3. The battery cell according to claim 1 or 2, characterized in that, The elastic modulus of the end region is greater than that of the middle region.

4. The battery cell of claim 3, wherein, Along the thickness direction of the composite current collector, the conductive structure layer in the end region includes a first conductive layer, a third conductive layer, a fourth conductive layer, and a second conductive layer arranged sequentially, and the conductive structure layer in the middle region includes the first conductive layer and the second conductive layer.

5. The battery cell of claim 4, wherein, The thickness of the third conductive layer and / or the fourth conductive layer at the first end is greater than or equal to the thickness of the third conductive layer and / or the fourth conductive layer at the second end. The first end is the end of the composite current collector located away from the middle region along the width direction of the composite current collector. The second end is the end of the composite current collector located close to the middle region along the width direction of the composite current collector.

6. The battery cell of claim 5, wherein, The thickness of the third conductive layer and / or the fourth conductive layer gradually decreases along the direction from the end region to the middle region.

7. The battery cell of claim 5, wherein, The third conductive layer and / or the fourth conductive layer are rectangular in shape.

8. The battery cell of any one of claims 5-7, wherein, The thickness of the third conductive layer and / or the fourth conductive layer at the first end is 0.5 μm to 3 μm.

9. The battery cell of claim 8, wherein, The thickness of the third conductive layer and / or the fourth conductive layer at the first end is 0.8 μm to 1.5 μm.

10. The battery cell of any one of claims 4-9, wherein, Along the width direction of the composite current collector, the dimensions of the third conductive layer and / or the fourth conductive layer are 0.05L0 to 0.12L0, where L0 is the dimension of the first conductive layer and / or the second conductive layer along the width direction of the composite current collector.

11. The battery cell of any one of claims 4-10, wherein, Along the width direction of the composite current collector, the dimensions of the third conductive layer and / or the fourth conductive layer are 5 mm to 12 mm.

12. The battery cell of any one of claims 3-11, wherein, 4500MPa≤G≤6000MPa.

13. The battery cell of any one of claims 3-12, wherein, 310 mg / 15 40.25 mm 2 ≤ A ≤ 450 mg / 15 40.25 mm 2 .

14. The battery cell of any one of claims 4-13, wherein, The thickness of the first conductive layer and / or the second conductive layer is 0.8 μm to 1.2 μm, and the thickness of the support layer is 6 μm to 10 μm.

15. The battery cell of claim 1 or 2, wherein, Along the thickness direction of the composite current collector, the conductive structure layer in the end region includes a first conductive layer and a second conductive layer, and the conductive structure layer in the middle region includes the first conductive layer and the second conductive layer.

16. The battery cell of claim 15, wherein, The thickness of the first conductive layer and / or the second conductive layer is 1.2 μm to 1.5 μm.

17. The battery cell of claim 16, wherein, The thickness of the support layer is 6μm to 10μm.

18. The battery cell of claim 16 or 17, wherein, 3600MPa≤G≤5000MPa.

19. The battery cell of any one of claims 16-18, wherein, 280 mg / 15 40.25 mm 2 ≤ A ≤ 390 mg / 15 40.25 mm 2 .

20. The battery cell of claim 15, wherein, The thickness of the support layer is 10μm to 15μm.

21. The battery cell of claim 20, wherein, The thickness of the first conductive layer and / or the second conductive layer is 0.5 μm to 1.0 μm.

22. The battery cell of claim 20 or 21, wherein, 4000MPa≤G≤5000MPa.

23. The battery cell of any one of claims 20-22, wherein, 280 mg / 15 40.25 mm 2 ≤ A ≤ 340 mg / 15 40.25 mm 2 .

24. The battery cell of any one of claims 1-23, wherein, The positive electrode sheet also includes a positive electrode tab, which protrudes from the composite current collector along the width direction of the composite current collector; The positive electrode sheet further includes an insulating layer, which is located closer to the positive electrode tab than the positive electrode film layer along the width direction of the composite current collector.

25. The battery cell of any one of claims 1-24, wherein, The positive electrode film layer includes a positive electrode active material, which includes lithium phosphate.

26. The battery cell of claim 25, wherein, The lithium-containing phosphate includes lithium iron phosphate.

27. The battery cell of claim 25 or 26, wherein, The lithium-containing phosphate satisfies at least one of the following conditions: The lithium-containing phosphate has a powder compaction density P1 at 3T that satisfies: 2.35 g / cm 3 ≤ P1 ≤ 2.65 g / cm 3 ; The discharge capacity Q0 of the lithium phosphate at 0.1C satisfies: 157.0 mAh / g ≤ Q0 ≤ 160.0 mAh / g; The initial coulombic efficiency of the lithium-containing phosphate satisfies: 99% ≤ K ≤ 100%.

28. The battery cell of any one of claims 25-27, wherein, The lithium-containing phosphate satisfies at least one of the following conditions: The water content B of the lithium phosphate satisfies: 0 ≤ B ≤ 500 ppm; The volume average particle size Dv50 of the lithium phosphate satisfies: 0.5μm≤Dv50≤3μm; The particle size distribution span of the lithium phosphate satisfies: (Dv90-Dv10) / Dv50≤3.

5.

29. The battery cell of claim 28, wherein, The lithium-containing phosphate satisfies at least one of the following conditions: The volume average particle size Dv50 of the lithium phosphate satisfies: 1μm≤Dv50≤3μm; The particle size distribution span of the lithium phosphate satisfies: (Dv90-Dv10) / Dv50≤2.

6.

30. The battery cell of claim 29, wherein, The lithium-containing phosphate satisfies at least one of the following conditions: The volume average particle size Dv50 of the lithium phosphate satisfies: 2μm≤Dv50≤3μm; The particle size distribution span of the lithium phosphate satisfies: (Dv90-Dv10) / Dv50≤2.

1.

31. The battery cell of any one of claims 1-30, wherein, The compacted density P2 of the positive electrode sheet satisfies: 2.55 g / cm 3 ≤ P2 ≤ 2.8 g / cm 3 .

32. The battery cell of any one of claims 1-31, wherein, The volumetric energy density of the battery cell is greater than or equal to 400Wh / L.

33. A battery device, characterized by include: Multiple battery cells according to any one of claims 1-32.

34. An electrical device, comprising: include: Multiple battery cells according to any one of claims 1-32, or battery devices according to claim 33, wherein the battery cells or battery devices are used to store or provide electrical energy.

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