Preparation method of composite current collector, battery cell, battery device and power consumption device

Abstract

This disclosure provides a method for preparing a composite current collector, a battery cell, a battery device, and an electrical device. The battery cell includes an electrode assembly, which in turn includes a composite current collector. The composite current collector includes an organic support layer and a metal layer located on at least one surface of the organic support layer. The metal layer has a porous structure. The organic support layer includes a central region and edge regions surrounding the central region. The edge regions of the organic support layer have at least one channel communicating with the central region. The sidewalls of the channels are provided with blocking portions, which are configured to ensure that the velocity of fluid flowing into the central region is greater than the velocity flowing into the edge regions. This disclosure can improve the cycle performance and reliability of the battery cell.

Description

Technical Field

[0001] This disclosure relates to the field of batteries, specifically to a method for preparing a composite current collector, a battery cell, a battery device, and an electrical device. Background Technology

[0002] Lithium-ion battery cells are widely used in power batteries, energy storage batteries and other fields. However, lithium-ion battery cells face the problem of poor electrolyte wetting in the middle area of ​​the electrode, which seriously affects the cycle performance and reliability of the battery cells. Summary of the Invention

[0003] This disclosure provides a method for preparing a composite current collector, a battery cell, a battery device, and an electrical device, which can improve the cycle performance and reliability of the battery cell.

[0004] In a first aspect, this disclosure provides a battery cell including an electrode assembly, the electrode assembly including a composite current collector, the composite current collector including an organic support layer and a metal layer located on at least one side surface of the organic support layer; the metal layer has a porous structure; the organic support layer includes a central region and an edge region located around the central region, the edge region of the organic support layer is provided with at least one channel communicating with the central region, the sidewall of the channel is provided with a blocking portion, the blocking portion is configured such that the velocity of fluid flowing into the central region in the channel is greater than the velocity of fluid flowing into the edge region.

[0005] The composite current collector of this disclosure includes an organic support layer and a metal layer located on at least one side surface of the organic support layer. The metal layer has a porous structure. At least one channel connecting to the intermediate region is provided in the edge region of the organic support layer. A blocking portion is provided on the sidewall of the channel, configured such that the velocity of fluid flowing into the intermediate region within the channel is greater than the velocity flowing into the edge region. This structural design of the composite current collector allows electrolyte to easily enter the intermediate region of the organic support layer from the edge region and makes it difficult for it to flow out from the edge region. The intermediate region of the organic support layer has good electrolyte retention capacity. The electrolyte in the intermediate region of the organic support layer, through the porous metal layer, wets the active material in the intermediate region, thereby effectively improving the wettability of the electrolyte to the intermediate region of the electrode. This reduces the problem of poor electrolyte wetting in the intermediate region of the electrode during battery cell cycling, thereby improving the cycle performance and reliability of the battery cell.

[0006] In some embodiments, the porosity of the middle region of the organic support layer is greater than the porosity of the edge region of the organic support layer.

[0007] In some embodiments, the average pore size of the middle region of the organic support layer is 1 μm-10 μm, and the porosity of the middle region of the organic support layer is 10%-30%.

[0008] In some embodiments, the average pore size of the edge region of the organic support layer is greater than or equal to 0 and less than 500 nm, and the porosity of the edge region of the organic support layer is greater than or equal to 0 and less than 10%.

[0009] In this embodiment, the porosity of the middle region of the organic support layer is greater than that of the edge region of the organic support layer, or the average pore size or porosity of the middle region of the organic support layer, or the average pore size or porosity of the edge region of the organic support layer, are within the above range. This allows the middle region of the composite current collector to store more electrolyte, while the edge region better blocks the outflow of electrolyte, further improving the electrolyte retention rate of the composite current collector.

[0010] In some embodiments, the channel has a depth direction, the dimension of which is the perpendicular distance between the first end and the second end of the channel; the dimension of the depth direction is 5%-15% of the width of the organic support layer.

[0011] In some embodiments, the edge region of the organic support layer is provided with multiple channels connecting the middle region, and the distance between two adjacent channels is 500μm-1mm.

[0012] By setting the dimension of the channel depth direction or the distance between two adjacent channels within the above-mentioned range, the electrolyte can flow more easily into the middle region of the support layer and be more difficult to flow out from the middle region, thereby further improving the liquid retention and storage capacity of the composite current collector.

[0013] In some embodiments, the channel is located within the organic support layer and has a width direction and a height direction. The height direction is parallel to the thickness direction of the organic support layer, the width direction and the height direction are in the same plane, and the plane formed by the width direction and the height direction is perpendicular to the plane of the organic support layer.

[0014] In some embodiments, the channel has a width dimension of 10 μm-30 μm and a height dimension of 50%-90% of the thickness of the organic support layer.

[0015] By limiting the dimensions of the channel in the width direction and the dimensions of the channel in the height direction, a suitable cross-sectional shape of the channel can be obtained, which further improves the liquid retention rate of the composite current collector. When the electrolyte in the middle region of the electrode is squeezed out, the electrolyte in the middle region of the composite current collector can timely and fully wet the active material, thereby further improving the cycle performance and reliability of the battery cell.

[0016] In some embodiments, the thickness of the organic support layer is 3 μm-8 μm. This can further improve the liquid retention rate of the composite current collector and increase the energy density of the battery cell.

[0017] In some embodiments, the blocking portion includes a plurality of obstructing mechanisms arranged at an angle, the obstructing mechanisms protruding from the sidewall, the obstructing mechanisms being rod-shaped or plate-shaped structures, the obstructing mechanisms having a first end connected to the sidewall and a second end protruding from the sidewall at an angle, the first end of the same obstructing mechanism being disposed away from the middle region relative to the second end.

[0018] In some embodiments, the tilt angle α of the obstruction mechanism is 30°-60°.

[0019] When the tilt angle α of the obstruction mechanism is within the above range, the obstruction mechanism can fully exert its effect of hindering the outflow of electrolyte, further improving the liquid retention rate of the composite current collector, thereby further improving the cycle performance and reliability of the battery cell.

[0020] In some embodiments, both sides of the channel are provided with a blocking mechanism, and the vertical distance x between the first ends of the blocking mechanisms on the two side walls is 10μm-30μm; the vertical distance y between the second ends of the blocking mechanisms on the two side walls is 5μm-15μm.

[0021] In some embodiments, multiple obstruction mechanisms are arranged sequentially on the same sidewall. The distance z between the first ends of adjacent obstruction mechanisms exposed in the channel on the same sidewall is 90μm-110μm, and the shortest distance s between the first ends of two adjacent obstruction mechanisms on the same sidewall is 45μm-55μm.

[0022] In some embodiments, the blocking portion includes a plurality of branches embedded in the sidewall. Each branch includes a connected arcuate portion and a straight portion. The arcuate portion has a first opening, and the straight portion has a second opening. The first and second openings are located on the sidewall surface and communicate with the channel. The first opening of the same branch is disposed away from the middle region relative to the second opening, and the straight portion is tangent to the arcuate portion.

[0023] In some embodiments, the channel has branches embedded in both opposite sidewalls, and the inner diameter of the branches is 8μm-12μm.

[0024] In some embodiments, the length a of the straight portion is 36μm-44μm, and the inclination angle β between the straight portion and the sidewall of the channel is 30°-60°.

[0025] In some embodiments, the channel has branches embedded in both opposite sidewalls, and the distance c between the channels with embedded branches is 18μm-22μm.

[0026] In some embodiments, the distance b between the second openings of two adjacent obstruction mechanisms in the channel depth direction is 90 μm-110 μm.

[0027] In some embodiments, the average pore size of the metal layer is 1 μm-30 μm, and the porosity of the metal layer is 10%-30%.

[0028] In some embodiments, the thickness of the metal layer is 3μm-10μm.

[0029] In some embodiments, the organic support layer comprises one or more of polyethylene terephthalate, polyethylene, polypropylene, epoxy resin, and polystyrene.

[0030] In some embodiments, the metal layer comprises one or more of aluminum, copper, nickel, titanium, silver, and their respective alloys.

[0031] Secondly, this disclosure provides a method for preparing a composite current collector, comprising: providing a stretched organic support layer, the organic support layer including a central region and an edge region surrounding the central region, the edge region of the organic support layer having at least one channel communicating with the central region, the sidewall of the channel having a blocking portion, the blocking portion being configured such that the velocity of fluid flowing from the channel to the central region is greater than the velocity flowing to the edge region; and depositing a metal layer on at least one side surface of the organic support layer to obtain a composite current collector; the metal layer having a porous structure.

[0032] Thirdly, this disclosure provides a battery device including a plurality of battery cells as described in the first aspect.

[0033] Fourthly, this disclosure provides an electrical device, including a battery cell as described in the first aspect or a battery device as described in the third aspect. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0035] Figure 1 This is a schematic diagram of a battery cell provided in some embodiments of this disclosure.

[0036] Figure 2 A schematic diagram of an electrical device provided for some embodiments of this disclosure.

[0037] Figure 3 This is a schematic diagram of the cross-sectional structure of the organic support layer provided in some embodiments of this disclosure.

[0038] Figure 4 A schematic cross-sectional view of the organic support layer provided for other embodiments of this disclosure.

[0039] Figure 5 A side view of an organic support layer structure provided for some embodiments of this disclosure.

[0040] Figure 6 This is a top view of a channel structure provided for some embodiments of this disclosure.

[0041] Figure 7 A top view of a channel structure provided for other embodiments of this disclosure.

[0042] Figure 8 This is a top view of the channel structure at the edge of the organic support layer in Comparative Example 1.

[0043] Figure 9 This is a schematic diagram showing the channels provided in some embodiments of the present disclosure arranged in an organic support layer.

[0044] Among them, 10 is the organic support layer; 11 is the middle region; 12 is the edge region; 13 is the channel; and 14 is the blocking part.

[0045] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0046] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the composite current collector preparation method, battery cell, battery device, and power-consuming device of this disclosure. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter of the claims.

[0047] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0048] Unless otherwise specified, all embodiments and optional embodiments of this disclosure may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the content of this disclosure.

[0049] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions, and such technical solutions should be considered as included in the content of this disclosure.

[0050] Unless otherwise specified, all steps in this disclosure may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0051] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0052] In the description of the embodiments of this disclosure, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0053] Unless otherwise stated, the test temperature for all parameters mentioned in this disclosure is 25°C.

[0054] The battery cells mentioned in this disclosure are capable of charging and discharging independently. The battery cells may be cuboid or other shapes. For example... Figure 1 This is a cuboid-shaped battery cell used as an example.

[0055] The battery apparatus mentioned in the embodiments of this disclosure may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0056] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0057] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0058] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0059] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0060] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0061] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0062] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0063] 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.

[0064] The technical solutions described in this disclosure are applicable to various electrical devices that use battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. Battery cells and battery devices are used to store or provide electrical energy.

[0065] Figure 2 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0066] During battery cell cycling, the electrode expands, squeezing out some of the electrolyte from the central area of ​​the electrode. If this squeezed-out electrolyte cannot flow back in time, it leads to poor electrolyte wetting in the central area, causing lithium plating, especially in the central area of ​​the negative electrode where expansion is significant. This can even cause the separator at the lithium plating site to completely adhere to the negative electrode, further exacerbating the poor electrolyte wetting.

[0067] Furthermore, current collectors typically lack the ability to retain and store liquid. Even when using composite current collectors with organic support layers, the density of the current collector can only be reduced, and the energy density of the battery cell can be increased. The improvement in the liquid retention and storage capabilities of the composite current collector is relatively limited.

[0068] In view of this, the present disclosure provides a method for preparing a composite current collector, a battery cell, a battery device, and an electrical device, which can improve the cycle performance and reliability of the battery cell.

[0069] This disclosure provides a battery cell including an electrode assembly, the electrode assembly including a composite current collector, the composite current collector including an organic support layer and a metal layer located on at least one surface of the organic support layer; the metal layer has a porous structure; Figure 3 This is a schematic diagram of the cross-sectional structure of the organic support layer provided in some embodiments of this disclosure, such as... Figure 3 As shown, the organic support layer 10 includes a central region 11 and an edge region 12 located around the central region. The edge region 12 of the organic support layer is provided with at least one channel 13 communicating with the central region 11. The sidewall of the channel 13 is provided with a blocking part 14. The blocking part 14 is configured such that the fluid in the channel 13 flows towards the central region 11 at a speed greater than the fluid flows towards the edge region 12.

[0070] The composite current collector of this disclosure includes an organic support layer and a metal layer located on at least one side surface of the organic support layer. The metal layer has a porous structure. At least one channel connecting to the intermediate region is provided in the edge region of the organic support layer. A blocking portion is provided on the sidewall of the channel, configured such that the velocity of fluid flowing into the intermediate region within the channel is greater than the velocity flowing into the edge region. This structural design of the composite current collector allows electrolyte to easily enter the intermediate region of the organic support layer from the edge region and makes it difficult for it to flow out from the edge region. The intermediate region of the organic support layer has good electrolyte retention capacity. The electrolyte in the intermediate region of the organic support layer, through the porous metal layer, wets the active material in the intermediate region, thereby effectively improving the wettability of the electrolyte to the intermediate region of the electrode. This reduces the problem of poor electrolyte wetting in the intermediate region of the electrode during battery cell cycling, thereby improving the cycle performance and reliability of the battery cell.

[0071] This embodiment of the invention sets the channel connecting the intermediate region as a structure similar to a "Tesla valve," allowing the electrolyte to easily enter but difficult to exit. That is, the electrolyte easily flows into the organic support layer through the channel, but is difficult to be squeezed out of the organic support layer. Most of the electrolyte wets the negative electrode active material through the porous metal layer. Furthermore, the channel is located at the edge of the organic support layer, allowing the electrolyte to quickly enter the intermediate region of the composite current collector and preventing it from overflowing, thus giving the composite current collector a certain liquid retention capacity.

[0072] In this embodiment, the electrolyte wetting path is from the edge region of the electrode to the middle region.

[0073] In some embodiments, a metal layer is disposed on both sides of the organic support layer.

[0074] It is understandable that lithium plating can occur in the negative electrode due to the extrusion of electrolyte in the central region. Therefore, composite current collectors are often used as negative electrode composite current collectors, thereby reducing lithium plating problems caused by poor electrolyte wetting in the central region of the negative electrode during battery cycling, thus improving the cycle performance and reliability of the battery cell. Of course, composite current collectors can also be used as positive electrode composite current collectors. In the embodiments of this disclosure, the central region of the electrode, the central region of the composite current collector, and the central region of the organic support layer correspond to each other.

[0075] In some embodiments, the channel is disposed at at least one end of the edge region of the organic support layer.

[0076] Please continue reading. Figure 3 In some embodiments, when the battery cell is a wound battery, the starting and ending ends of the winding may not have a channel connecting the intermediate region. That is, the two ends of the composite current collector in the length direction do not have a channel connecting the intermediate region, but only the two ends of the composite current collector in the width direction have a channel connecting the intermediate region.

[0077] Figure 4 This is a schematic diagram of the cross-sectional structure of the organic support layer provided in other embodiments of this disclosure, such as... Figure 4 As shown, in some embodiments, when the battery cell is a stacked battery, channels connecting to the middle region are provided in the edge regions around the composite current collector, that is, channels connecting to the middle region are provided at both ends of the composite current collector in the length direction and at both ends of the width direction.

[0078] Apart from the channels connecting to the middle region, the edge region of the organic support layer has no pores or very small pore size and porosity.

[0079] In some embodiments, the porosity of the middle region 11 of the organic support layer is greater than the porosity of the edge region 12 of the organic support layer.

[0080] In some embodiments, the average pore size of the middle region of the organic support layer can be 1μm-10μm, for example, it can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any range of the above values.

[0081] In some embodiments, the porosity of the middle region of the organic support layer can be 10%-30%, for example, it can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, or any of the above values.

[0082] In some embodiments, the average pore size of the edge region of the organic support layer is greater than or equal to 0 and less than 500 nm, for example, it can be 0-400 nm, 0-300 nm, 0-200 nm, 0-100 nm, or 0-50 nm.

[0083] In some embodiments, the average pore size of the edge region of the organic support layer is 0. In this case, the edge region of the organic support layer has no pores other than channels.

[0084] In some embodiments, the porosity of the edge region of the organic support layer is greater than or equal to 0 and less than 10%, for example, it can be 0-8%, 0-6%, 0-4%, or 0-2%.

[0085] In some embodiments, the porosity of the edge region of the organic support layer is 0. In this case, the edge region of the organic support layer has no pores except for the channels.

[0086] In this embodiment, the porosity of the middle region of the organic support layer is greater than that of the edge region, or the average pore size or porosity of the middle region of the organic support layer, or the average pore size or porosity of the edge region of the organic support layer, are within the aforementioned range. This allows the middle region of the composite current collector to store more electrolyte, while the edge region better prevents electrolyte outflow, further improving the electrolyte retention rate of the composite current collector. When the aforementioned composite current collector is applied to the negative electrode, even when the electrolyte in the middle region of the negative electrode sheet is squeezed out, the electrolyte in the middle region of the negative electrode composite current collector can promptly and fully wet the negative electrode active material, thereby further improving the cycle performance and reliability of the battery cell.

[0087] Please continue reading. Figure 3 In some embodiments, the channel has a depth direction, the dimension of which is the perpendicular distance between the first end and the second end of the channel; the depth dimension H1 is 5%-15% of the width of the organic support layer, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any range of the above values. It should be noted that the depth of the channels in the edge region of the organic support layer is the same, all being 5%-15% of the width of the organic support layer.

[0088] In some embodiments, the channel may be arranged perpendicular to the length direction or the width direction of the organic support layer.

[0089] Figure 9 This is a schematic diagram illustrating the arrangement of channels within an organic support layer, as provided in some embodiments of this disclosure. (See diagram for example.) Figure 9 As shown, in some embodiments, the channel can be obliquely disposed inside the edge region (the blocking part is not shown), that is, the angle between the channel and the length direction or the width direction of the organic support layer is greater than 90° or less than 90°.

[0090] In some embodiments, the edge region of the organic support layer is provided with multiple channels connecting the middle region, and the distance D between two adjacent channels can be 500μm-1mm, for example, it can be 500μm, 600μm, 700μm, 800μm, 900μm, 1mm, or any range of the above values.

[0091] This embodiment of the invention, by setting the dimension of the channel depth or the distance between two adjacent channels within the aforementioned range, allows the electrolyte to flow more easily into the middle region of the support layer and makes it more difficult for it to flow out from the middle region, further improving the electrolyte retention and storage capacity of the composite current collector. When the composite current collector is used as the negative electrode, during battery cycling, the expansion of the negative electrode sheet squeezes out the electrolyte between the negative electrode sheet and the separator. The electrolyte stored inside the composite current collector can then promptly wet the negative electrode active material, further reducing the problem of lithium plating due to poor wetting of the negative electrode, thereby further improving the cycle performance and reliability of the battery cell.

[0092] Figure 5 For a side view of the organic support layer structure provided in some embodiments of this disclosure, please refer to... Figure 3 and Figure 5 In some embodiments, the channel is located within the organic support layer and has a width direction and a height direction. The height direction is parallel to the thickness direction of the organic support layer, the width direction and the height direction are in the same plane, and the plane formed by the width direction and the height direction is perpendicular to the plane of the organic support layer.

[0093] In some embodiments, the channel dimension w in the width direction can be 10μm-30μm, for example, it can be 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, 22μm, 24μm, 26μm, 28μm, 30μm, or any range of the above values.

[0094] "Dimension of the channel in the width direction" refers to the distance of an opening of a single channel in the width or length direction of the organic support layer.

[0095] Please continue reading. Figure 5 In some embodiments, the dimension H2 of the channel in the height direction can be 50%-90% of the thickness of the organic support layer, for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or any range of the above values.

[0096] By limiting the dimensions of the channel in the width direction and the dimensions of the channel in the height direction, a suitable cross-sectional shape of the channel can be obtained, which further improves the liquid retention rate of the composite current collector. When the electrolyte in the middle region of the electrode is squeezed out, the electrolyte in the middle region of the composite current collector can timely and fully wet the active material, thereby further improving the cycle performance and reliability of the battery cell.

[0097] In some embodiments, the thickness of the organic support layer can be 3μm-8μm, for example, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, or any range of the above values. This can further improve the liquid retention rate of the composite current collector and increase the energy density of the battery cell.

[0098] Figure 6 This is a top view of the channel structure provided in some embodiments of this disclosure, such as... Figure 6 As shown, in some embodiments, the blocking part includes a plurality of inclined blocking mechanisms that protrude from the sidewall. The blocking mechanism is a rod-shaped or plate-shaped structure. The blocking mechanism has a first end connected to the sidewall and a second end that protrudes from the sidewall and is inclined. The first end of the same blocking mechanism is disposed in the middle region relative to the second end.

[0099] In some embodiments, the opening direction of the tilt angle α of the obstruction mechanism is toward the middle region of the organic support layer.

[0100] Please continue reading. Figure 6 In some embodiments, the tilt angle α of the obstruction mechanism can be 30°-60°, for example, it can be 30°, 35°, 40°, 45°, 50°, 55°, 60°, or any range of the above values.

[0101] When the tilt angle α of the obstruction mechanism is within the above range, the obstruction mechanism can fully exert its effect of hindering the outflow of electrolyte, further improving the liquid retention rate of the composite current collector, thereby further improving the cycle performance and reliability of the battery cell.

[0102] In some embodiments, both sides of the channel are provided with a blocking mechanism, and the vertical distance x between the first ends of the blocking mechanisms on the two side walls can be 10μm-30μm, for example, 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, 22μm, 24μm, 26μm, 28μm, or 30μm.

[0103] In some embodiments, the vertical distance y between the second ends of the obstruction mechanisms arranged on the two sidewalls can be 5μm-15μm, for example, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, or 15μm.

[0104] With y as a constant, increasing x allows more electrolyte to enter the middle region of the organic support layer. The vertical distance x between the first ends of the deflection mechanisms on the two sidewalls is within the above range, which can further improve the liquid retention rate of the composite current collector.

[0105] In this embodiment of the present disclosure, the vertical distance y between the second ends of the obstruction mechanisms arranged on the two side walls is within the above-mentioned range, which can further enhance the obstruction effect of the channel on the outflow of electrolyte and further improve the liquid retention rate of the composite current collector.

[0106] In some embodiments, the value of x is greater than the value of y.

[0107] In some embodiments, multiple obstruction mechanisms are arranged sequentially on the same sidewall, and the distance z between the first ends of adjacent obstruction mechanisms exposed in the channel on the same sidewall can be 90μm-110μm, for example, 90μm, 95μm, 100μm, 105μm, or 110μm.

[0108] In some embodiments, the number of obstruction mechanisms on the same sidewall can be 2, 4, or 6.

[0109] In some embodiments, two obstruction mechanisms are arranged sequentially on the same sidewall.

[0110] In some embodiments, the shortest distance s between the first ends of two adjacent obstruction mechanisms disposed on the same sidewall can be 45μm-55μm, for example, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, or 55μm.

[0111] Figure 7 This is a top view of the channel structure provided in other embodiments of this disclosure, such as... Figure 7 As shown, in some embodiments, the blocking portion includes multiple branches embedded in the sidewall. Each branch includes a connected arcuate portion and a straight portion. The arcuate portion has a first opening, and the straight portion has a second opening. The first and second openings are located on the sidewall surface and communicate with the channel. The first opening of the same branch is disposed away from the middle region relative to the second opening, and the straight portion is tangent to the arcuate portion.

[0112] In some embodiments, the channel has branches embedded in both opposite sidewalls, and the inner diameter of the branches is 8μm-12μm, for example, 8μm, 9μm, 10μm, 11μm, or 12μm.

[0113] Please continue reading. Figure 7In some embodiments, the arc portion includes a first arc and a second arc, the radius of the first arc is r1, the radius of the second arc is r2, and the difference between r2 and r1 is the inner diameter of the aforementioned branch.

[0114] In some embodiments, the length 'a' of the straight portion can be 36μm-44μm, for example, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, or 44μm; the inclination angle β between the straight portion and the sidewall of the channel can be 30°-60°, for example, 30°, 35°, 40°, 45°, 50°, 55°, or 60°.

[0115] In some embodiments, the opening direction of the tilt angle β of the straight portion is toward the edge region of the organic support layer.

[0116] In some embodiments, the channel is embedded with branches in both opposite sidewalls, and the distance c between the channels with embedded branches can be 18μm-22μm, for example, 18μm, 19μm, 20μm, 21μm, or 22μm.

[0117] In some embodiments, the branches of the two opposite sidewalls are symmetrically arranged along the centerline of the channel, and each branch has the same shape.

[0118] In some embodiments, the branches embedded in the same sidewall have the same shape.

[0119] In some embodiments, the distance b between the second openings of two adjacent obstruction mechanisms in the channel depth direction can be 90μm-110μm, for example, 90μm, 95μm, 100μm, 105μm, or 110μm.

[0120] In some embodiments, the number of branches embedded in the sidewall on the same side can be 2, 4 or 6. For example, the number of branches embedded in the sidewall on the same side is 2.

[0121] During the process of electrolyte flowing from the organic support layer into the cell, the liquid vortex formed by the arc part in the branch will hinder the outflow of electrolyte, improve the liquid retention capacity of the composite current collector, and thus further improve the cycle performance and reliability of the battery cell.

[0122] In some embodiments, the average pore size of the metal layer can be 1μm-30μm, for example, it can be 1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, or any range of the above values.

[0123] In some embodiments, the porosity of the metal layer can be 10%-30%, for example, it can be 10%, 15μm, 20μm, 25μm, 30%, or any of the above values.

[0124] If the average pore size or porosity of the metal layer is within the above range, the electrolyte in the middle region of the organic support layer can pass smoothly through the metal layer even when the electrolyte in the middle region of the electrode is squeezed out, so as to replenish the electrolyte in the middle region of the electrode in a timely manner.

[0125] In some embodiments, the thickness of the metal layer can be 3μm-10μm, for example, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any range of the above values. This can improve the energy density of the battery cell.

[0126] In some embodiments, the organic support layer may include one or more of polyethylene terephthalate, polyethylene, polypropylene, epoxy resin, and polystyrene.

[0127] In some embodiments, the metal layer may include one or more of aluminum, copper, nickel, titanium, silver, and their respective alloys.

[0128] In some embodiments, the negative electrode sheet may include a negative electrode film layer disposed on at least one surface of the negative electrode composite current collector and comprising a negative electrode active material. For example, the negative electrode composite current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode composite current collector.

[0129] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, mesophase microcarbon spheres, silicon-based materials, and tin-based materials. Silicon-based materials may include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include at least one of elemental tin, tin oxides, and tin alloys. However, this disclosure is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0130] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0131] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), 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).

[0132] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0133] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode composite current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, negative electrode conductive agent, negative electrode binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0134] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may also include a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode composite current collector and the negative electrode film layer and disposed on the surface of the negative electrode composite current collector; in some embodiments, the negative electrode sheet may also include a protective layer covering the surface of the negative electrode film layer.

[0135] [Preparation method of composite current collector]

[0136] This disclosure provides a method for preparing a composite current collector, the method comprising the following steps:

[0137] S10: Provide a stretched organic support layer; the organic support layer includes a central region and an edge region surrounding the central region, the edge region of the organic support layer is provided with at least one channel communicating with the central region, the sidewall of the channel is provided with a blocking part, the blocking part is configured such that the velocity of fluid flowing into the central region in the channel is greater than the velocity of fluid flowing into the edge region.

[0138] S20: A metal layer is disposed on at least one side surface of the organic support layer to obtain a composite current collector; the metal layer has a porous structure.

[0139] In some embodiments, the preparation method further includes melting and mixing the organic polymer to obtain a molten organic polymer; cooling the molten organic polymer in a mold to obtain a cast sheet of the organic polymer; and stretching the cast sheet to obtain an organic support layer.

[0140] It is understandable that the shape of the mold edge area can be similar to... Figure 6 , Figure 7 The shape of the channel is set accordingly.

[0141] In some embodiments, the stretching process can be performed using a bidirectional asynchronous stretching machine to stretch the casting along both the length and width directions.

[0142] In some embodiments, the surface of the metal layer has through holes. The through holes on the surface of the metal layer may be located only in the middle region of the organic support layer, or they may be located in both the middle and edge regions of the organic support layer.

[0143] In some embodiments, the metal layer can be deposited on at least one side surface of the organic support layer by means of vapor deposition, chemical plating, evaporation, or adhesion. During the fabrication of the metal layer, through holes can be formed on the surface of the metal layer by means of a mask, or through holes can be formed on the surface of the metal layer by laser etching after the metal layer has been fabricated.

[0144] In some embodiments, the metal layer may be a porous metal structure.

[0145] [Positive electrode plate]

[0146] In some embodiments, the electrode assembly further includes a positive electrode sheet, which may also include a positive electrode film layer disposed on at least one side surface of the positive electrode composite current collector.

[0147] The positive electrode active material may include one or more of lithium transition metal oxides and their modified materials, lithium phosphates and their modified materials, lithium titanate, sulfur, selenium, and tellurium.

[0148] Optionally, examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and lithium-rich manganese-based materials.

[0149] Optionally, examples of lithium phosphates may include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0150] In some embodiments, to further improve the energy density of a single battery cell, the positive electrode active material may include materials of the general formula Li. a Ni b Co c M d O e A fOne or more of lithium transition metal oxides and their modified materials. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M may include one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A may include one or more of N, F, S and Cl.

[0151] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811), LiNi 0.83 Mn 0.08 Co 0.07 O2 (abbreviated as Ni83), LiNi 0.90 Mn 0.05 Co 0.05 O2 (abbreviated as Ni90), LiNi 0.94 Mn 0.03 Co 0.03 O2 (abbreviated as Ni94), LiNi 0.96 Co 0.02 Mn 0.02 O2 (abbreviated as Ni96), LiNi 0.80 Co 0.15 Al 0.05 One or more of O2, LiFePO4, LiMnPO4 and their respective modified materials.

[0152] During the charging and discharging process, lithium (Li) undergoes insertion / extraction and consumption within a single battery cell, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar Li content represents the initial state of the material, i.e., the state before material addition. As the positive electrode active material is applied to the battery cell, the molar Li content changes after charge-discharge cycles. Similarly, the molar O content in the examples of positive electrode active materials in this disclosure is only a theoretical value. Oxygen release from the crystal lattice causes changes in the molar O content, leading to fluctuations in the actual molar O content.

[0153] The modified materials for the above-mentioned positive electrode active materials can be doped and / or surface coated.

[0154] In some embodiments, the positive electrode film layer may further include a positive electrode binder, which may include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0155] In some embodiments, the positive electrode film may further include a positive electrode conductive agent, which may include, but is not limited to, one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor-grown carbon fibers (VGCF).

[0156] [Isolation membrane]

[0157] In some embodiments, the separator is disposed between the positive and negative electrodes. The separator in this disclosure can be a porous structure separator with good chemical and mechanical stability.

[0158] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0159] Alternatively, an inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating may be applied to the surface of the separator.

[0160] [Electrolytes]

[0161] Each battery cell includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This disclosure does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte may include one or more of solid electrolytes, gel electrolytes, and liquid electrolytes (i.e., electrolyte solutions).

[0162] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0163] There are no specific restrictions on the types of electrolyte salts; they can be selected according to actual needs.

[0164] In some embodiments, the electrolyte salt may be one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0165] There are no specific restrictions on the type of solvent; it can be selected according to actual needs.

[0166] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate (PPC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE). An ether solvent may also be selected. Ether solvents may include one or more of the following: ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, and crown ether.

[0167] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve the overcharge / fast charge performance of individual battery cells, additives that improve the high-temperature performance of individual battery cells, additives that improve the low-temperature performance of individual battery cells, etc.

[0168] The gel electrolyte includes a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0169] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0170] As an example, the polymers of polymeric solid electrolytes may include polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids, cellulose, etc.

[0171] As an example, inorganic solid electrolytes can be one or more of the following: oxide solid electrolytes (crystalline perovskite, lithium superconducting ion conductors, garnet, amorphous LiPON thin films), sulfide solid electrolytes (crystalline lithium superconducting ion conductors, amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0172] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0173] In some embodiments, the battery cell may also include an outer packaging. The outer packaging may be a rigid shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging may also be a flexible package, such as a pouch-type flexible package. The material of the flexible package may be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0174] In some embodiments, the outer packaging of a single battery cell is a hard shell.

[0175] Methods for preparing battery cells are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process. Exemplarily, the positive electrode, separator, and negative electrode are wound on a mandrel to form a cylindrical structure. After the mandrel is removed, the cylindrical structure is flattened to form a wound cell. The electrode assembly is placed in an outer packaging, dried, and then injected with the electrolyte. After vacuum sealing, settling, and formation processes, a battery cell is obtained.

[0176] Example

[0177] The following examples describe the contents of this disclosure in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0178] Example 1

[0179] Preparation of the negative electrode sheet: Polypropylene particles are melted and mixed to obtain an organic polymer solution. This solution is then cooled on a molding die to obtain a cast organic polymer sheet. The sheet is then stretched along both the length and width directions using a biaxial asynchronous stretching machine, avoiding the edge regions. This results in an organic support layer with an average pore size of 10 μm and a porosity of 20% in the central region, and an average pore size of less than 500 nm and a porosity of less than 10% in the edge regions. The thickness of the organic support layer is 5 μm. The channel structure at both ends of the width direction of the organic support layer is as follows... Figure 6 In the structure of A2, the angle α is 30°, x is 10μm, and y is 5μm; the distance z between the first ends of the obstruction mechanism exposed in the channel is 100μm, and the shortest distance s between the first ends of two adjacent obstruction mechanisms on the same sidewall is 50μm.

[0180] The organic support layer is placed in a vacuum plating chamber, and the high-purity copper wire in the metal evaporation chamber is melted and evaporated at a high temperature of 1300℃-2000℃. The evaporated metal passes through the cooling system in the vacuum plating chamber and is finally deposited on both sides of the organic support layer in the thickness direction. Then, through holes with a diameter of 10μm and a porosity of 10% are etched on the metal layer by laser etching, and finally the negative electrode composite current collector is obtained.

[0181] The negative electrode active material graphite, the negative electrode conductive agent acetylene black, the negative electrode binder styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) were mixed in a mass ratio of 94:2:3:1. Deionized water was added as a solvent, and the mixture was stirred thoroughly to obtain a uniform negative electrode slurry. The negative electrode slurry was then coated onto both surfaces of the negative electrode composite current collector, dried, and cold-pressed to a density of 1.65 g / cm³. 3 This yields the negative electrode sheet.

[0182] Preparation of the positive electrode sheet: The positive electrode active material MCM811, the positive electrode conductive agent acetylene black, and the positive electrode binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 94:4:2. N-methylpyrrolidone solvent was added, and the mixture was thoroughly stirred to obtain a uniform positive electrode slurry. This slurry was then coated onto both surfaces of an aluminum-based current collector, dried, and cold-pressed to a density of 1.65 g / cm³. 3 This yields the positive electrode sheet.

[0183] Preparation of electrolyte: In an argon atmosphere glove box with a water content of <10ppm, ethylene carbonate (EC), polycarbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of EC:PC:DMC = 3:3:3. Then, LiPF6, VC, DTD, and PS were added and stirred until homogeneous to obtain the electrolyte. The concentration of LiPF6 in the electrolyte was 1 mol / L. Based on the total mass of the electrolyte being 100%, the mass percentages of VC, DTD, and PS were 3%, 1%, and 1%, respectively.

[0184] The negative electrode and positive electrode prepared according to the above method are sequentially wound from the first layer to the last layer, forming a bare cell by winding the die-cut separator, negative electrode, separator, positive electrode, separator, etc. The bare cell is then placed in an outer packaging and injected with electrolyte. After formation, aging and other processes, a battery cell is obtained.

[0185] Example 2

[0186] Except for the negative electrode sheet, where x is 20 μm, the preparation methods for the other battery cells are the same as in Example 1.

[0187] Example 3

[0188] Except for the negative electrode sheet, where x is 30 μm, the preparation methods for the other battery cells are the same as in Example 1.

[0189] Example 4

[0190] Except for the negative electrode sheet, where x is 20 μm and y is 10 μm, the preparation methods for the other battery cells are the same as in Example 1.

[0191] Example 5

[0192] Except for the negative electrode sheet, where x is 20 μm and y is 15 μm, the preparation methods for the other battery cells are the same as in Example 1.

[0193] Example 6

[0194] Except for the negative electrode sheet, where x is 30 μm and y is 10 μm, the preparation methods for the other battery cells are the same as in Example 1.

[0195] Example 7

[0196] Except for the negative electrode sheet, where x is 30 μm and y is 15 μm, the preparation methods for the other battery cells are the same as in Example 1.

[0197] Example 8

[0198] In addition to the channel structure at both ends of the organic support layer in the width direction during the preparation of the negative electrode sheet, the process is as follows: Figure 7 Except for the structure of A3, where angle β is 30°, a is 40μm, b is 100μm, and c is 20μm, the preparation method of the other battery cells is the same as in Example 1.

[0199] Example 9

[0200] Except for the negative electrode sheet, where the angle β is 45°, the preparation methods for the other battery cells are the same as in Example 8.

[0201] Example 10

[0202] Except for the fact that the angle β is 60° during the preparation of the negative electrode sheet, the preparation method of the other battery cells is the same as in Example 8.

[0203] Comparative Example 1

[0204] In addition to the channel structure at both ends of the organic support layer in the width direction during the preparation of the negative electrode sheet, the process is as follows: Figure 8 Except for the structure of A1, where the opening distance w is 20 μm, the preparation method of the other battery cells is the same as in Example 8.

[0205] Comparative Example 2

[0206] Except for the fact that the edge region of the organic support layer is not treated during the preparation of the negative electrode sheet, i.e., the average pore size of the organic support layer is 10 μm and the porosity is 20%, the preparation method of the other battery cells is the same as in Example 8.

[0207] Test section

[0208] (1) Test of liquid retention rate of negative electrode composite current collector

[0209] Take 20 layers of the prepared negative electrode composite current collector, each 100mm × 100mm in size, stack them together, and clamp them with two aluminum clamps. Record the weight as m0. Then, immerse the current collector and clamps in electrolyte for 2 hours. Remove the current collector and wait until the electrolyte is dripping. Wipe away any remaining electrolyte on the surface of the aluminum clamps with lint-free paper. Record the weight as m1. Next, apply a pressure of 500N-3000N (simulating the state of a single battery cell in a battery pack) to both sides of the clamps using an automatic press. Hold for 3 minutes and record the weight as m2. Calculate the liquid retention rate of the negative electrode composite current collector using the following formula:

[0210]

[0211] in, θ The liquid retention rate of the negative electrode composite current collector is expressed in units of %.

[0212] (2) Cycle performance test of individual battery cells

[0213] Under a constant temperature environment of 25℃, the capacitor was charged to 4.4V with a constant current of 1C, then charged to 0.05C with a constant voltage of 4.4V until the current dropped to 0.05C, and finally discharged to 2.5V with a constant current of 1C. The first discharge specific capacity (C) was obtained. d1 Repeat this charge-discharge cycle until the 500th cycle, and the discharge specific capacity after 500 cycles is denoted as C. dn .

[0214] Capacity retention (%) = Discharge specific capacity after 500 cycles (C) dn ) / First-cycle discharge specific capacity (C d1 ).

[0215] (3) Determination of lithium plating grade of negative electrode sheet

[0216] After cycling the battery cell 500 times according to the above-described cycling method, disassemble the battery cell and further separate the positive electrode and negative electrode. Observe the lithium deposition in the bending area and the middle area of ​​the negative electrode. The judgment criteria are shown in Table 1.

[0217] Table 1

[0218]

[0219] The relevant parameters of Examples 1-10 and Comparative Examples 1-2, as well as the test results of the liquid retention rate of the negative electrode composite current collector, the capacity retention rate of the battery cell after 500 cycles, and the lithium plating grade, are shown in Table 2.

[0220] Table 2

[0221]

[0222] As can be seen from Examples 1-10 and Comparative Examples 1-2, Figure 7 The structure of A3 has a branch. When the electrolyte flows from the organic support layer into the cell, the liquid vortex formed by the arc of the branch severely hinders the outflow of the electrolyte, thus giving the organic support layer a better liquid retention capacity. However, when the β angle is too small, the formed liquid vortex may not be large, so the effect of hindering the outflow of liquid is not obvious. Therefore, the liquid retention rate of the negative electrode composite current collector in Example 8 is lower than that when β is 45°. But when β is too large, because the angle at which the straight part of the branch intersects with the main channel is too large, the electrolyte rarely passes through the branch channel when it flows out, so the effect of hindering the outflow of liquid is not obvious. The liquid retention rate of the negative electrode composite current collector in Example 10 is also lower than that when β is 45°.

[0223] For adoption Figure 6 In the embodiment of the A2 structure, when y is 5 μm, as x increases, more electrolyte can enter the middle region of the organic support layer, so the liquid retention rate of the corresponding negative electrode composite current collector is relatively high. When y is 10 μm and x is 20 μm, compared with the case of x being 20 μm and y being 5 μm, because y is larger, it is conducive to the entry of electrolyte, and the liquid retention rate of the negative electrode composite current collector is higher. When x is 30 μm and y is 10 μm, compared with the case of x being 20 μm and y being 10 μm, it is possible that the inflow of electrolyte is not significantly increased, and the liquid retention rate of the negative electrode composite current collector is not much different. However, when y increases to 15 μm, the obstruction effect on electrolyte outflow is greatly weakened, and the liquid retention rate of the negative electrode composite current collector is lower.

[0224] The test results in Table 2 also show that... Figure 6 and Figure 7 The negative electrode composite current collector formed by the organic support layer of the structure has excellent liquid retention capacity, which in turn gives the battery cell excellent cycle performance. The underlying reason is that the improved liquid retention rate of the negative electrode composite current collector effectively improves the wetting state of the electrolyte in the middle region of the negative electrode, thereby effectively improving lithium plating in the middle region.

[0225] It should be noted that this disclosure 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 disclosure are included within the technical scope of this disclosure. 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, are also included within the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. A battery cell, comprising an electrode assembly, the electrode assembly including a composite current collector, characterized in that, The composite current collector includes an organic support layer and a metal layer located on at least one surface of the organic support layer; the metal layer has a porous structure. The organic support layer includes a central region and an edge region surrounding the central region. The edge region of the organic support layer is provided with at least one channel communicating with the central region. The sidewall of the channel is provided with a blocking portion, which is configured to cause the fluid in the channel to flow towards the central region at a speed greater than the fluid to flow towards the edge region.

2. The battery cell according to claim 1, characterized in that, The porosity of the middle region of the organic support layer is greater than that of the edge region of the organic support layer.

3. The battery cell according to claim 1, characterized in that, The average pore size of the middle region of the organic support layer is 1μm-10μm, and the porosity of the middle region of the organic support layer is 10%-30%; and / or, The average pore size of the edge region of the organic support layer is greater than or equal to 0 and less than 500 nm, and the porosity of the edge region of the organic support layer is greater than or equal to 0 and less than 10%.

4. The battery cell according to claim 1, characterized in that, The channel has a depth direction, the dimension of which is the perpendicular distance between the first end and the second end of the channel; the dimension of the depth direction is 5%-15% of the width of the organic support layer; and / or, The edge region of the organic support layer is provided with multiple channels connecting the middle region, and the distance between two adjacent channels is 500μm-1mm.

5. The battery cell according to claim 1, characterized in that, The channel is located within the organic support layer. The channel has a width direction and a height direction. The height direction is parallel to the thickness direction of the organic support layer. The width direction and the height direction are located in the same plane, and the plane formed by the width direction and the height direction is perpendicular to the plane of the organic support layer.

6. The battery cell according to claim 5, characterized in that, The channel has a width dimension of 10μm-30μm, and the channel's height dimension is 50%-90% of the organic support layer thickness; and / or, The thickness of the organic support layer is 3μm-8μm.

7. The battery cell according to claim 1, characterized in that, The blocking part includes a plurality of inclined blocking mechanisms, each blocking mechanism protruding from the sidewall. Each blocking mechanism is rod-shaped or plate-shaped, and has a first end connected to the sidewall and a second end protruding from the sidewall and inclined. The first end of the same blocking mechanism is positioned away from the intermediate region relative to the second end, and the blocking mechanism satisfies one or more of the following conditions (1)-(3): (1) The tilt angle α of the obstruction mechanism is 30°-60°; (2) The two opposite sidewalls of the channel are provided with the obstruction mechanism, and the vertical distance x between the first ends of the obstruction mechanism on the two sidewalls is 10μm-30μm; the vertical distance y between the second ends of the obstruction mechanism on the two sidewalls is 5μm-15μm; (3) Multiple obstruction mechanisms are arranged sequentially on the same sidewall. The distance z between the first ends of adjacent obstruction mechanisms exposed in the channel on the same sidewall is 90μm-110μm. The shortest distance s between the first ends of two adjacent obstruction mechanisms on the same sidewall is 45μm-55μm.

8. The battery cell according to claim 1, characterized in that, The blocking portion includes multiple branches embedded in the sidewall. Each branch includes a connected arc portion and a straight portion. The arc portion has a first opening, and the straight portion has a second opening. The first opening and the second opening are located on the surface of the sidewall and communicate with the channel. The first opening of the same branch is positioned away from the intermediate region relative to the second opening. The straight portion is tangent to the arc portion, and the blocking portion satisfies one or more of the following conditions (1)-(4): (1) The channel is inlaid with the branch in each of the two opposite side walls, and the inner diameter of the branch is 8μm-12μm; (2) The length a of the straight section is 36μm-44μm, and the inclination angle β between the straight section and the sidewall of the channel is 30°-60°; (3) The channel is inlaid with the branch in each of the two opposite side walls, and the distance c between the channels inlaid with the branch is 18μm-22μm; (4) The distance b between the second openings of two adjacent branches in the channel depth direction is 90μm-110μm.

9. The battery cell according to claim 1, characterized in that, The average pore size of the metal layer is 1 μm-30 μm, and the porosity of the metal layer is 10%-30%; and / or, The thickness of the metal layer is 3μm-10μm.

10. The battery cell according to claim 1, characterized in that, The organic support layer comprises one or more of polyethylene terephthalate, polyethylene, polypropylene, epoxy resin, and polystyrene; and / or, The metal layer includes one or more of aluminum, copper, nickel, titanium, silver, and their respective alloys.

11. A method for preparing a composite current collector, characterized in that, include: A stretched organic support layer is provided, the organic support layer including a central region and an edge region surrounding the central region, the edge region of the organic support layer being provided with at least one channel communicating with the central region, the sidewall of the channel being provided with a blocking portion, the blocking portion being configured such that the velocity of fluid flowing into the central region from the channel is greater than the velocity flowing into the edge region. A metal layer is disposed on at least one surface of the organic support layer to obtain a composite current collector; the metal layer has a porous structure.

12. A battery device, characterized in that, It includes the battery cells described in any one of claims 1-10.

13. An electrical appliance, characterized in that, Includes the battery cell as described in any one of claims 1-10 or the battery device as described in claim 12.

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