Preparation method of composite current collector, battery monomer, battery device and power utilization device

Abstract

The invention provides a preparation method of a composite current collector, a battery monomer, a battery device and a power utilization device, the battery monomer comprises an electrode assembly, the electrode assembly comprises the composite current collector, and the composite current collector comprises 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 supporting layer comprises a middle area and an edge area located around the middle area, the edge area of the organic supporting layer is provided with at least one channel communicated with the middle area, the side wall of the channel is provided with a blocking part, and the blocking part is configured to enable the speed of fluid in the channel flowing towards the middle area to be larger than the speed of fluid flowing towards the edge area. The cycle performance and the reliability of the battery monomer can be improved.

Description

Technical Field

[0001] The present disclosure relates to the field of batteries, and in particular to a method for preparing a composite current collector, a battery cell, a battery device, and an electrical device. Background Art

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

[0003] The present disclosure provides a preparation method of 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, the present disclosure provides a battery cell, comprising an electrode assembly, the electrode assembly comprising a composite current collector, the composite current collector comprising 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 comprises a middle region and an edge region located around the middle region, the edge region of the organic support layer is provided with at least one channel connected to the middle region, the sidewall of the channel is provided with a blocking portion, the blocking portion being configured to allow the fluid in the channel to flow toward the middle region at a faster rate than the fluid flowing toward the edge region.

[0005] The composite current collector of the disclosed embodiment includes an organic support layer and a metal layer located on at least one side surface of the organic support layer, wherein the metal layer has a porous structure. At least one channel connected to the middle region is provided in the edge region of the organic support layer, and a barrier portion is provided on the side wall of the channel. The barrier portion is configured to allow the fluid in the channel to flow toward the middle region at a faster rate than the fluid flowing toward the edge region. The structural design of the composite current collector makes it easy for the electrolyte to enter the middle region of the organic support layer from the edge region and difficult to flow out from the edge region of the organic support layer. The middle region of the organic support layer has good liquid retention capacity. The electrolyte in the middle region of the organic support layer infiltrates the active material in the middle region through the metal layer having a porous structure, thereby effectively improving the wettability of the electrolyte to the middle region of the electrode, reducing the problem of poor electrolyte infiltration in the middle region of the electrode during the cycle of the battery cell, thereby improving the cycle performance and reliability of the battery cell.

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

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

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

[0009] In the embodiment of the present disclosure, 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, 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 is within the above range, so that the middle region of the composite current collector can store more electrolyte, and the edge region can better block the outflow of electrolyte, further improving the liquid retention rate of the composite current collector.

[0010] In some embodiments, the channel has a depth direction, and the dimension of the depth direction is a vertical distance between the first end of the channel 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, a plurality of channels communicating with the middle region are provided in the edge region of the organic support layer, and the distance between two adjacent channels is 500 μm-1 mm.

[0012] By setting the channel depth dimension or the distance between two adjacent channels within the above range, the embodiment of the present disclosure can make it easier for the electrolyte to flow into the middle area of ​​the support layer and more difficult to flow out of the middle area, thereby further improving the liquid retention and storage capacity of the composite current collector.

[0013] In some embodiments, the channel is located in the organic support layer, and 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 where the organic support layer is located.

[0014] In some embodiments, the channel has a dimension in a width direction of 10 μm to 30 μm, and a dimension in a height direction of the channel is 50% to 90% of the thickness of the organic supporting layer.

[0015] By limiting the dimensions of the channel in the width direction and the channel in the height direction, a suitable cross-sectional shape of the channel can be obtained, further improving the liquid retention rate of the composite current collector. When the electrolyte in the middle area of ​​the electrode is squeezed out, the electrolyte in the middle area of ​​the composite current collector can timely and fully infiltrate 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 to 8 μm, thereby further improving the liquid retention rate of the composite current collector and increasing the energy density of the battery cell.

[0017] In some embodiments, the blocking portion includes a plurality of obstruction mechanisms that are arranged at an angle, the obstruction mechanisms are arranged to protrude from the side wall, the obstruction mechanisms are rod-shaped or plate-shaped structures, the obstruction mechanisms have a first end connected to the side wall, and a second end that is arranged to protrude from the side wall and is inclined, and the first end of the same obstruction mechanism is arranged away from the middle area relative to the second end.

[0018] In some embodiments, the obstruction mechanism has an inclination angle α of 30°-60°.

[0019] When the inclination angle α of the obstruction mechanism is within the above range, the obstruction mechanism can fully exert its effect of hindering the outflow of the 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, two opposite side walls of the channel are provided with obstruction mechanisms, and the vertical distance x between the first ends of the obstruction mechanisms on the two side walls is 10 μm-30 μm; the vertical distance y between the second ends of the obstruction mechanisms on the two side walls is 5 μm-15 μm.

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

[0022] In some embodiments, the blocking portion includes a plurality of branches embedded in the side wall, the branches include a connected arc portion and a straight portion, the arc portion has a first opening, the straight portion has a second opening, the first opening and the second opening are located on the side wall surface and are connected to the channel, and the first opening of the same branch is arranged away from the middle area relative to the second opening, and the straight portion is tangent to the arc portion.

[0023] In some embodiments, branches are embedded in two opposite side walls of the channel, and the inner diameter of the branches is 8 μm-12 μm.

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

[0025] In some embodiments, branches are inlaid in two opposite sidewalls of the channel, and a distance c between the channels inlaid with branches is 18 μm-22 μm.

[0026] In some embodiments, a 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 3 μm-10 μm.

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

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

[0031] In a second aspect, the present disclosure provides a method for preparing a composite current collector, comprising: providing an organic support layer that has been stretched, the organic support layer comprising a middle region and an edge region located around the middle region, the edge region of the organic support layer being provided with at least one channel connected to the middle region, the sidewall of the channel being provided with a blocking portion, the blocking portion being configured to allow the fluid in the channel to flow toward the middle region at a greater speed than that flowing toward the edge region; providing 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] In a third aspect, the present disclosure provides a battery device comprising a plurality of battery cells according to the first aspect.

[0033] In a fourth aspect, the present disclosure provides an electrical device comprising the battery cell of the first aspect or the battery device of the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on the drawings without inventive effort.

[0035] Figure 1 Schematic diagram of a battery cell provided for some embodiments of the present disclosure.

[0036] Figure 2 A schematic diagram of an electrical device provided in some embodiments of the present disclosure.

[0037] Figure 3 Schematic diagram of the cross-sectional structure of the organic support layer provided in some embodiments of the present disclosure.

[0038] Figure 4 Schematic diagram of the cross-sectional structure of the organic support layer provided in some other embodiments of the present disclosure.

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

[0040] Figure 6 A top view of a channel structure provided for some embodiments of the present disclosure.

[0041] Figure 7 A top view of the channel structure provided for some other embodiments of the present disclosure.

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

[0043] Figure 9 Schematic diagram of channels provided in an organic support layer according to some embodiments of the present disclosure.

[0044] Among them, 10, organic support layer; 11, middle region; 12, edge region; 13, channel; 14, barrier; In the accompanying drawings, the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0045] Below, with appropriate reference to the accompanying drawings, the embodiments of the composite current collector preparation method, battery cells, battery devices, and electrical devices disclosed herein are described in detail. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially identical structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter described in the claims.

[0046] " scope " disclosed in the present disclosure is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and selected lower limit and upper limit define the boundary of special scope.The scope that this mode limits can be to include end value or not include end value, and can be combined arbitrarily, and promptly any lower limit can form a scope with any upper limit combination.For example, if the scope of 60-120 and 80-110 is listed for specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.In addition, if the minimum range value 1 and 2 listed, and if the maximum range value 3,4 and 5 listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.In the present disclosure, unless otherwise specified, numerical range " ab " represents the abbreviation of any real number combination between a and b, and wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0047] Unless otherwise specified, all embodiments and optional embodiments of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the content of the present disclosure.

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

[0049] Unless otherwise specified, all steps of the present disclosure may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0050] In the present disclosure, the terms "plurality" and "multiplicity" refer to two or more.

[0051] In the description of the embodiments of the present disclosure, unless otherwise specified, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0052] Unless otherwise stated, the test temperature for each parameter mentioned in this disclosure is 25°C.

[0053] The battery cells mentioned in the embodiments of the present disclosure can independently realize the functions of charging and discharging. The battery cells can be rectangular or in other shapes. Figure 1 A rectangular parallelepiped battery cell is shown as an example.

[0054] The battery apparatus mentioned in the embodiments of the present disclosure may include one or more battery cell assemblies to provide voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or hybrid via a busbar.

[0055] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells.

[0056] As an example, the battery cell assembly may be a battery module, which is formed by arranging and fixing multiple battery cells to form an independent module. As an example, the battery module may be formed by bundling multiple battery cells with a cable tie.

[0057] In some embodiments, the battery device may be a battery pack, which includes a case and one or more battery cell assemblies, wherein the battery cell assemblies are housed in the case.

[0058] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box by fixing the battery module in the box.

[0059] As an example, the battery cell assembly may also be housed in the box by directly fixing the plurality of battery cells to the box.

[0060] As an example, the housing may include a first housing and a second housing. The first housing and the second housing engage to form an enclosed space within the housing to house the battery cell assembly. Enclosed here means covered or closed, and can be either sealed or unsealed. The first housing may be a top cover or a bottom plate.

[0061] As an example, the box may include a top cover, a frame, and a bottom plate, wherein the top cover and the bottom plate are respectively connected to the frame to form a closed space inside the box to accommodate the battery cell assembly.

[0062] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0063] The technical solutions described in the embodiments of this disclosure are applicable to various electrical devices that use battery cells and battery devices, including, 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, satellites, and energy storage systems. Battery cells and battery devices are used to store or provide electrical energy.

[0064] Figure 2 1 is a schematic diagram of an exemplary electric device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0065] During the battery cell cycle, the electrode will swell, squeezing out some of the electrolyte in the middle area of ​​the electrode. The squeezed electrolyte in the middle area of ​​the electrode cannot flow back in time, resulting in poor electrolyte wetting in the middle area of ​​the electrode. This can cause lithium deposition in the electrode, especially in the middle area of ​​the negative electrode, where the expansion is greater. It can even cause the separator and the negative electrode to completely bond together at the lithium deposition location, exacerbating the poor electrolyte wetting of the electrode.

[0066] In addition, the current collector usually does not have the ability to retain and store liquid. Even if a composite current collector with an organic support layer is used, it can only reduce the density of the current collector and increase the energy density of the battery cell. The degree of improvement in the composite current collector's ability to retain and store liquid is relatively limited.

[0067] 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.

[0068] The present disclosure provides a battery cell, comprising an electrode assembly, the electrode assembly comprising a composite current collector, the composite current collector comprising an organic support layer and a metal layer located on at least one side of the organic support layer; the metal layer has a porous structure; Figure 3 A schematic diagram of the cross-sectional structure of an organic support layer provided in some embodiments of the present disclosure, such as Figure 3 As shown, the organic support layer 10 includes a middle region 11 and an edge region 12 located around the middle region. The edge region 12 of the organic support layer is provided with at least one channel 13 connected to the middle region 11. The sidewall of the channel 13 is provided with a blocking portion 14. The blocking portion 14 is configured to allow the fluid in the channel 13 to flow toward the middle region 11 at a faster speed than the fluid flowing toward the edge region 12.

[0069] The composite current collector of the disclosed embodiment includes an organic support layer and a metal layer located on at least one side surface of the organic support layer, wherein the metal layer has a porous structure. At least one channel connected to the middle region is provided in the edge region of the organic support layer, and a barrier portion is provided on the side wall of the channel. The barrier portion is configured to allow the fluid in the channel to flow toward the middle region at a faster rate than the fluid flowing toward the edge region. The structural design of the composite current collector makes it easy for the electrolyte to enter the middle region of the organic support layer from the edge region and difficult to flow out from the edge region of the organic support layer. The middle region of the organic support layer has good liquid retention capacity. The electrolyte in the middle region of the organic support layer infiltrates the active material in the middle region through the metal layer having a porous structure, thereby effectively improving the wettability of the electrolyte to the middle region of the electrode, reducing the problem of poor electrolyte infiltration in the middle region of the electrode during the cycle of the battery cell, thereby improving the cycle performance and reliability of the battery cell.

[0070] In the disclosed embodiments, the channels connecting the central region are configured as a "Tesla valve"-like structure, making it easy for the electrolyte to enter the channels but difficult to exit. Specifically, the electrolyte easily flows into the organic support layer through the channels, but is difficult to squeeze out of the organic support layer. The majority of the electrolyte penetrates the porous metal layer and soaks into the negative electrode active material. Furthermore, the channels are located at the edge of the organic support layer, allowing the electrolyte to quickly enter the central region of the composite current collector and making it difficult for the electrolyte to overflow from the central region, thus ensuring a certain degree of liquid retention in the composite current collector.

[0071] In the embodiment of the present disclosure, the electrolyte infiltration route is from the edge area to the middle area of ​​the electrode.

[0072] In some embodiments, the metal layer is disposed on both sides of the organic supporting layer.

[0073] It is understandable that the negative electrode plate will undergo lithium deposition due to the extrusion of the electrolyte in the middle area. Therefore, the composite current collector can usually be used as a negative electrode composite current collector, thereby reducing the problem of lithium deposition in the middle area of ​​the negative electrode plate due to poor electrolyte infiltration during the cycle of the battery cell, thereby improving the cycle performance and reliability of the battery cell. Of course, the composite current collector can also be used as a positive electrode composite current collector. In the embodiment of the present disclosure, the middle area of ​​the electrode plate and the middle area of ​​the composite current collector correspond to the middle area of ​​the organic support layer.

[0074] In some embodiments, the channel is disposed at at least one end of an edge region of the organic supporting layer.

[0075] Please continue reading Figure 3 In some embodiments, when the battery cell is a wound battery, a channel connecting to the middle region may not be provided at the starting end and the ending end of the winding, that is, no channel connecting to the middle region is provided at both ends of the composite current collector in the length direction, and a channel connecting to the middle region is provided only at both ends of the composite current collector in the width direction.

[0076] Figure 4 Schematic diagram of the cross-sectional structure of the organic support layer provided in some other embodiments of the present disclosure, such as Figure 4 As shown, in some embodiments, when the battery cell is a laminated battery, channels connecting to the middle area are provided at the edge areas around the composite current collector, that is, channels connecting to the middle area are provided at both ends in the length direction and both ends in the width direction of the composite current collector.

[0077] Except for the channel connected to the middle region, the edge region of the organic support layer has no pores at other positions of the edge region, or the pore diameter and porosity are very small.

[0078] In some embodiments, the porosity of the middle region 11 of the organic supporting layer is greater than the porosity of the edge region 12 of the organic supporting layer.

[0079] In some embodiments, the average pore size of the middle region of the organic support layer can be 1 μm-10 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a range consisting of any of the above values.

[0080] In some embodiments, the porosity of the middle region of the organic support layer can be 10%-30%, for example, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, or a range consisting of any of the above values.

[0081] In some embodiments, the average pore size of the edge region of the organic supporting layer is greater than or equal to 0 and less than 500 nm, for example, 0-400 nm, 0-300 nm, 0-200 nm, 0-100 nm, or 0-50 nm.

[0082] In some embodiments, the average pore size of the edge region of the organic supporting layer is 0. In this case, the edge region of the organic supporting layer has no pores except the channels.

[0083] In some embodiments, the porosity of the edge region of the organic supporting layer is greater than or equal to 0 and less than 10%, for example, it may be 0-8%, 0-6%, 0-4%, or 0-2%.

[0084] In some embodiments, the porosity of the edge region of the organic supporting layer is 0. In this case, the edge region of the organic supporting layer has no pores except the channels.

[0085] In the disclosed embodiments, the porosity of the central region of the organic support layer is greater than the porosity of the edge region of the organic support layer, or the average pore size or porosity of the central region of the organic support layer, or the average pore size or porosity of the edge region of the organic support layer is within the above range. This allows the central region of the composite current collector to store more electrolyte, and the edge region to better block the outflow of electrolyte, further improving the liquid retention rate of the composite current collector. When the composite current collector is applied to the negative electrode, if the electrolyte in the central region of the negative electrode pole piece is squeezed out, the electrolyte in the central region of the negative composite current collector can promptly and fully infiltrate the negative electrode active material, thereby further improving the cycle performance and reliability of the battery cell.

[0086] Please continue reading Figure 3 In some embodiments, the channel has a depth dimension, where the depth dimension H1 is the perpendicular distance between the first end of the channel and the second end of the channel. The depth dimension H1 is 5%-15% of the width of the organic support layer, and can be, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any range thereof. It should be noted that the depth of the channels in the edge region of the organic support layer is the same, being 5%-15% of the width of the organic support layer.

[0087] In some embodiments, the channel may be disposed perpendicular to the length direction of the organic supporting layer or the width direction of the organic supporting layer.

[0088] Figure 9 Schematic diagram of channels provided in an organic support layer according to some embodiments of the present disclosure. Figure 9 As shown, in some embodiments, the channel can be tilted inside the edge region (the blocking portion is not shown), that is, the angle between the channel and the length direction or the width direction of the organic supporting layer is greater than 90° or less than 90°.

[0089] In some embodiments, the edge region of the organic support layer is provided with a plurality of channels connected to the middle region, and the distance D between two adjacent channels can be 500 μm-1 mm, for example, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1 mm, or a range consisting of any of the above values.

[0090] By setting the channel depth dimension or the distance between two adjacent channels within the above range, the disclosed embodiment can make it easier for the electrolyte to flow into the middle area of ​​the support layer and more difficult to flow out of the middle area, further improving the composite current collector's liquid retention and storage capacity. The composite current collector is used for the negative electrode. During the cycle of the battery cell, the negative electrode plate expands and squeezes out the electrolyte between the negative electrode plate and the separator. The electrolyte stored in the composite current collector can promptly infiltrate the negative electrode active material, further reducing the problem of lithium plating due to poor infiltration of the negative electrode, thereby further improving the cycle performance and reliability of the battery cell.

[0091] Figure 5 For side views of the organic support layer structure provided in some embodiments of the present disclosure, please refer to Figure 3 and Figure 5 In some embodiments, the channel is located in the organic support layer, and 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 where the organic support layer is located.

[0092] In some embodiments, the dimension w of the channel 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 a range consisting of any of the above values.

[0093] The “dimension of a channel in the width direction” refers to the distance of an opening of a single channel in the width direction or the length direction of the organic supporting layer.

[0094] 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 a range consisting of any of the above values.

[0095] By limiting the dimensions of the channel in the width direction and the channel in the height direction, a suitable cross-sectional shape of the channel can be obtained, further improving the liquid retention rate of the composite current collector. When the electrolyte in the middle area of ​​the electrode is squeezed out, the electrolyte in the middle area of ​​the composite current collector can timely and fully infiltrate the active material, thereby further improving the cycle performance and reliability of the battery cell.

[0096] In some embodiments, the thickness of the organic support layer may be 3 μm to 8 μm, for example, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or any range thereof. This can further improve the liquid retention rate of the composite current collector and increase the energy density of the battery cell.

[0097] Figure 6 A top view of the channel structure provided in some embodiments of the present disclosure, such as Figure 6 As shown, in some embodiments, the blocking portion includes a plurality of obstruction mechanisms that are arranged obliquely, the obstruction mechanisms are arranged to protrude from the side wall, the obstruction mechanisms are rod-shaped or plate-shaped structures, the obstruction mechanisms have a first end connected to the side wall, and a second end that protrudes from the side wall and is obliquely arranged, and the first end of the same obstruction mechanism is arranged relative to the middle area of ​​the second end.

[0098] In some embodiments, the opening direction of the obstruction mechanism at the tilt angle α is toward the middle region of the organic supporting layer.

[0099] Please continue reading Figure 6 In some embodiments, the inclination angle α of the obstruction mechanism can be 30°-60°, for example, it can be 30°, 35°, 40°, 45°, 50°, 55°, 60°, or a range consisting of any of the above values.

[0100] When the inclination angle α of the obstruction mechanism is within the above range, the obstruction mechanism can fully exert its effect of hindering the outflow of the electrolyte, further improving the liquid retention rate of the composite current collector, thereby further improving the cycle performance and reliability of the battery cell.

[0101] In some embodiments, two opposite side walls of the channel are provided with obstruction mechanisms, and the vertical distance x between the first ends of the obstruction mechanisms on the two side walls can be 10μm-30μm, for example, it can be 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, 22μm, 24μm, 26μm, 28μm, or 30μm.

[0102] In some embodiments, the vertical distance y between the second ends of the obstruction mechanisms arranged on the two side walls can be 5μm-15μm, for example, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, or 15μm.

[0103] When y is a constant value, an increase in x can allow more electrolyte to enter the middle area of ​​the organic support layer. The vertical distance x between the first ends of the obstruction mechanisms on the two side walls is within the above range, which can further improve the liquid retention rate of the composite current collector.

[0104] In the 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 range, which can further enhance the channel's blocking effect on electrolyte outflow and further enhance the liquid retention rate of the composite current collector.

[0105] In some embodiments, the value of x is greater than the value of y.

[0106] In some embodiments, multiple obstruction mechanisms are arranged in sequence on the same side wall, and the distance z between the first ends of adjacent obstruction mechanisms on the same side wall exposed in the channel can be 90μm-110μm, for example, 90μm, 95μm, 100μm, 105μm, or 110μm.

[0107] In some embodiments, the number of the same side wall obstruction mechanism can be 2, 4 or 6.

[0108] In some embodiments, two blocking mechanisms are arranged in sequence on the same side wall.

[0109] In some embodiments, the shortest distance s between the first ends of two adjacent obstruction mechanisms on the same side wall may be 45 μm-55 μm, for example, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm, 51 μm, 52 μm, 53 μm, 54 μm, or 55 μm.

[0110] Figure 7 A top view of the channel structure provided in some other embodiments of the present disclosure, such as Figure 7 As shown, in some embodiments, the blocking portion includes a plurality of branches embedded in the side wall, the branches include a connected arc portion and a straight portion, the arc portion has a first opening, the straight portion has a second opening, the first opening and the second opening are located on the side wall surface and are connected to the channel, and the first opening of the same branch is arranged away from the middle area relative to the second opening, and the straight portion is tangent to the arc portion.

[0111] In some embodiments, branches are embedded in two opposite side walls of the channel, and the inner diameter of the branches is 8 μm-12 μm, for example, 8 μm, 9 μm, 10 μm, 11 μm, or 12 μm.

[0112] 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 branch.

[0113] In some embodiments, the length a of the straight portion can be 36 μm-44 μm, for example, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, or 44 μm; the inclination angle β between the straight portion and the side wall of the channel can be 30°-60°, for example, 30°, 35°, 40°, 45°, 50°, 55°, or 60°.

[0114] In some embodiments, the opening direction of the inclination angle β of the straight portion is toward the edge region of the organic supporting layer.

[0115] In some embodiments, branches are embedded in two opposite side walls of the channel, and the distance c between the channels embedded with branches can be 18 μm-22 μm, for example, 18 μm, 19 μm, 20 μm, 21 μm, or 22 μm.

[0116] In some embodiments, the branches on two opposite side walls are symmetrically arranged along the center line of the channel, and the branches have the same shape.

[0117] In some embodiments, the branches embedded in the same sidewall have the same shape.

[0118] In some embodiments, the distance b between the second openings of two adjacent obstruction mechanisms in the channel depth direction may be 90 μm-110 μm, for example, 90 μm, 95 μm, 100 μm, 105 μm, or 110 μm.

[0119] In some embodiments, the number of branches embedded in the sidewall on the same side may be 2, 4, or 6. Exemplarily, the number of branches embedded in the sidewall on the same side is 2.

[0120] During the process of the electrolyte flowing out from the organic support layer to the battery cell, the liquid vortex formed in the arc part of the branch will hinder the outflow of the electrolyte, thereby improving the liquid retention capacity of the composite current collector, thereby further improving the cycle performance and reliability of the battery cell.

[0121] In some embodiments, the average pore size of the metal layer may be 1 μm-30 μm, for example, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, or any range thereof.

[0122] In some embodiments, the porosity of the metal layer may be 10%-30%, for example, 10%, 15 μm, 20 μm, 25 μm, 30%, or any range thereof.

[0123] The average pore size or porosity of the metal layer is within the above range, so that when the electrolyte in the middle area of ​​the electrode is squeezed out, the electrolyte in the middle area of ​​the organic support layer can pass through the metal layer smoothly, thereby replenishing the electrolyte in the middle area of ​​the electrode in time.

[0124] In some embodiments, the thickness of the metal layer may be 3 μm-10 μm, for example, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any range thereof, thereby increasing the energy density of the battery cell.

[0125] In some embodiments, the organic support layer may include one or more of polyester terephthalate, polyethylene, polypropylene, epoxy resin, and polystyrene.

[0126] In some embodiments, the metal layer may include one or more of aluminum, copper, nickel, titanium, silver, and alloys thereof.

[0127] In some embodiments, the negative electrode sheet may include a negative electrode film layer disposed on at least one surface of a negative electrode composite current collector and comprising a negative electrode active material. For example, the negative electrode composite current collector may have two opposing surfaces in its thickness direction, and the negative electrode film layer may be disposed on either or both of the two opposing surfaces of the negative electrode composite current collector.

[0128] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery cell that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, mesophase microcarbon beads, 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, the present disclosure is not limited to these materials, and other traditional 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.

[0129] 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.

[0130] In some embodiments, the negative electrode film layer may further include a negative electrode binder. For 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, water-based 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).

[0131] In some embodiments, the negative electrode film layer may further include other additives, such as thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, and the like.

[0132] The negative electrode film layer is typically formed by coating the negative electrode slurry onto the negative electrode composite current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing the negative electrode active material, negative electrode conductive agent, negative electrode binder, and other optional additives in a solvent and stirring them evenly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0133] The negative electrode plate does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode plate may further include a conductive primer layer (e.g., composed of a conductive agent and a binder) 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 plate may further include a protective layer covering the surface of the negative electrode film layer.

[0134] [Method for preparing composite current collector] The present disclosure provides a method for preparing a composite current collector, the preparation method comprising the following steps: S10: Providing a stretched organic support layer; the organic support layer includes a middle region and edge regions surrounding the middle region; the edge regions of the organic support layer are provided with at least one channel communicating with the middle region; a sidewall of the channel is provided with a blocking portion, the blocking portion being configured to cause a fluid in the channel to flow toward the middle region at a greater speed than that flowing toward the edge regions; S20: Disposing a metal layer on at least one surface of the organic support layer to obtain a composite current collector; the metal layer has a porous structure.

[0135] 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 casting of the organic polymer, and stretching the casting to obtain an organic support layer.

[0136] It will be appreciated that the shape of the edge region of the mould may vary with Figure 6 、 Figure 7The shape of the channel corresponds to the settings.

[0137] In some embodiments, the stretching process may use a bidirectional asynchronous stretching machine to perform regional stretching along the length direction and the width direction of the cast sheet.

[0138] In some embodiments, the surface of the metal layer has through holes, and the through holes on the surface of the metal layer can be arranged only in the middle area of ​​the organic support layer, or in both the middle area and the edge area of ​​the organic support layer.

[0139] In some embodiments, the metal layer may be deposited on at least one surface of the organic support layer by vapor deposition, chemical plating, evaporation, bonding, etc. During the preparation of the metal layer, through holes may be formed on the surface of the metal layer by masking, or after the metal layer is prepared, through holes may be formed on the surface of the metal layer by laser etching.

[0140] In some embodiments, the metal layer may be a porous metal structure.

[0141] [Positive electrode] In some embodiments, the electrode assembly further includes a positive electrode sheet, and the positive electrode sheet may further include a positive electrode film layer disposed on at least one side of the surface of the positive electrode composite current collector.

[0142] The positive electrode active material may include one or more of lithium transition metal oxides and modified materials thereof, lithium-containing phosphates and modified materials thereof, lithium titanate, sulfur, selenium, and tellurium.

[0143] Optionally, examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium manganese-rich based materials.

[0144] Optionally, examples of lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0145] In some embodiments, in order to further improve the energy density of the battery cell, the positive electrode active material may include a general formula of Li a Ni b Co c M d O e A fOne or more lithium transition metal oxides and modified materials thereof. 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.

[0146] As an example, the positive electrode active material may include but is not limited to LiCoO2, LiNiO2, LiMnO2, LiMn2O4, 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.

[0147] Battery cells experience Li intercalation and deintercalation during the charge and discharge process, resulting in different molar Li contents in different discharge states. The molar Li contents listed in this disclosure for positive electrode active materials refer to the initial state of the material, i.e., the state before addition. The molar Li contents of positive electrode active materials used in battery cells will change after charge and discharge cycles. The molar O contents listed in this disclosure for positive electrode active materials are only theoretical values. Lattice oxygen release can cause changes in the molar O content, and the actual molar O content will also fluctuate.

[0148] The modified materials of the above-mentioned positive electrode active materials may be the positive electrode active materials subjected to doping modification and / or surface coating modification.

[0149] 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 fluorine-containing acrylic resin.

[0150] In some embodiments, the positive electrode film layer 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).

[0151] [Isolation film] In some embodiments, the separator is disposed between the positive electrode and the negative electrode. The separator of the embodiment of the present disclosure can be a porous structure separator with good chemical stability and mechanical stability.

[0152] As an example, the primary material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. 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.

[0153] Optionally, an inorganic particle coating, an organic particle coating or an organic / inorganic composite coating may be coated on the surface of the isolation membrane.

[0154] [Electrolytes] Battery cells contain an electrolyte, which conducts ions between the positive and negative electrodes. The present disclosure does not specifically limit the type of electrolyte; it can be selected based on specific needs. For example, the electrolyte can include one or more of a solid electrolyte, a gel electrolyte, and a liquid electrolyte (i.e., an electrolyte solution).

[0155] In some embodiments, the electrolyte is an electrolyte solution including an electrolyte salt and a solvent.

[0156] The type of electrolyte salt is not particularly limited and can be selected according to actual needs.

[0157] In some embodiments, the electrolyte salt may include, but is not limited to, 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 difluorooxalatoborate (LiDFOB), lithium bis(oxalatoborate) (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalatophosphate) (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).

[0158] The type of solvent is not particularly limited and can be selected according to actual needs.

[0159] In some embodiments, the solvent may include at least one of 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), butylene 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), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE). The solvent may also be an ether solvent. The ether solvent may include one or more of 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.

[0160] 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, or additives that can improve certain battery properties, such as additives that improve the overcharge / fast charge performance of battery cells, additives that improve the high-temperature performance of battery cells, and additives that improve the low-temperature performance of battery cells.

[0161] Among them, the gel electrolyte includes a polymer as a skeleton network and can be used in combination with an ionic liquid-lithium salt.

[0162] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0163] As an example, the polymer of the polymer solid electrolyte may include polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, a polyionic liquid, cellulose, and the like.

[0164] As an example, the inorganic solid electrolyte can be one or more of an oxide solid electrolyte (crystalline perovskite, lithium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor, amorphous sulfide), a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0165] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0166] In some embodiments, the battery cell may further include an outer packaging. The outer packaging may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0167] In some embodiments, the outer packaging of the battery cell is a hard shell.

[0168] The preparation method of battery cells is well known. In some embodiments, the positive electrode sheet, separator, negative electrode sheet and electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, separator and negative electrode sheet can be formed into an electrode assembly through a winding process. For example, the positive electrode sheet, separator and negative electrode sheet are wound on a winding mandrel to form a cylindrical structure. After the winding mandrel is removed, the cylindrical structure is flattened to form a wound battery cell. The electrode assembly is placed in an outer packaging, dried, and then the above-mentioned electrolyte is injected. After vacuum packaging, standing, formation and other processes, a battery cell is obtained.

[0169] Example The following examples further describe the present disclosure, which are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further processing, and all instruments used in the examples are commercially available.

[0170] Example 1 Preparation of negative electrode: Organic polymer polypropylene particles are melted and mixed to obtain an organic polymer solution, which is then cooled on a forming mold to obtain an organic polymer casting sheet. The casting sheet is then stretched in the length and width directions using a bidirectional asynchronous stretching machine, avoiding the edge areas around the casting sheet, to obtain an organic support layer with an average pore size of 10μm and a porosity of 20% in the middle area, an average pore size of less than 500nm and a porosity of less than 10% in the edge area, and a thickness of 5μm. 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 10 μm, and y is 5 μm; the distance z between the first ends of the obstruction mechanisms exposed in the channel is 100 μm, and the shortest distance s between the first ends of two adjacent obstruction mechanisms arranged on the same side wall is 50 μm.

[0171] 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 an aperture of 10μm and a porosity of 10% are etched on the metal layer by laser scoring, and finally a negative electrode composite current collector is obtained.

[0172] The negative electrode active material graphite, negative electrode conductive agent acetylene black, negative electrode binder styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) were mixed in a mass ratio of 94:2:3:1, and deionized water was added as solvent. The mixture was stirred thoroughly to obtain the negative electrode slurry. The negative electrode slurry was then coated on both surfaces of the negative electrode composite current collector, dried, and cold pressed to 1.65 g / cm 3 , and obtain the negative electrode sheet.

[0173] Preparation of positive electrode sheet: Mix the positive electrode active material MCM811, the positive electrode conductive agent acetylene black, and the positive electrode binder polyvinylidene fluoride (PVDF) in a mass ratio of 94:4:2, add the solvent N-methylpyrrolidone, stir and mix thoroughly to obtain the positive electrode slurry, and then apply it to the two surfaces of the aluminum-based current collector, dry and cold press to 1.65g / cm 3 , and obtain the positive electrode.

[0174] 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, and then LiPF6, VC, DTD, and PS were added and stirred evenly to obtain an electrolyte. The concentration of LiPF6 in the electrolyte was 1 mol / L. Based on the total mass of the electrolyte as 100%, the mass percentages of VC, DTD, and PS were 3%, 1%, and 1%, respectively.

[0175] The negative electrode sheets and positive electrode sheets prepared according to the above method are wound together with the die-cut isolation film, negative electrode sheet, isolation film, positive electrode sheet, isolation film... from the first layer to the last layer to form a bare battery cell. The bare battery cell is placed in an outer package and injected with electrolyte. After that, the battery cell is obtained through processes such as formation and aging.

[0176] Example 2 The preparation method of the remaining battery cells is the same as that of Example 1, except that x is 20 μm during the preparation of the negative electrode sheet.

[0177] Example 3 The preparation method of the remaining battery cells is the same as that of Example 1, except that x is 30 μm during the preparation of the negative electrode sheet.

[0178] Example 4 The preparation method of the remaining battery cells is the same as that of Example 1, except that x is 20 μm and y is 10 μm during the preparation of the negative electrode sheet.

[0179] Example 5 The preparation method of the remaining battery cells is the same as that of Example 1, except that x is 20 μm and y is 15 μm during the preparation of the negative electrode sheet.

[0180] Example 6 The preparation method of the rest of the battery cells is the same as that of Example 1, except that x is 30 μm and y is 10 μm during the preparation of the negative electrode sheet.

[0181] Example 7 The preparation method of the remaining battery cells is the same as that of Example 1, except that x is 30 μm and y is 15 μm during the preparation of the negative electrode sheet.

[0182] Example 8 In addition to the channel structure at both ends of the width direction of the organic support layer during the preparation of the negative electrode, Figure 7 In the structure of A3, the angle β is 30°, a is 40 μm, b is 100 μm, and c is 20 μm. The preparation method of the remaining battery cells is the same as that of Example 1.

[0183] Example 9 The preparation method of the rest of the battery cells is the same as that of Example 8, except that the angle β is 45° during the preparation of the negative electrode sheet.

[0184] Example 10 The preparation method of the rest of the battery cells is the same as that of Example 8, except that the angle β is 60° during the preparation of the negative electrode plate.

[0185] Comparative Example 1 In addition to the channel structure at both ends of the width direction of the organic support layer during the preparation of the negative electrode, Figure 8 The preparation method of the remaining battery cells is the same as that of Example 8 except that the opening distance w is 20 μm in the structure of A1.

[0186] Comparative Example 2 The preparation method of the rest of the battery cells is the same as that of Example 8, except that the edge area of ​​the organic support layer is not processed during the preparation of the negative electrode plate, that is, the average pore size of the organic support layer is 10 μm and the porosity is 20%.

[0187] Test section (1) Liquid retention rate test of negative electrode composite current collector Take 20 layers of the prepared negative electrode composite current collector, measuring 100mm×100mm, stack them together and clamp them with two aluminum clamps. The weight is recorded as m0. Then, soak them together with the clamps in the electrolyte for 2 hours and remove them. When the electrolyte begins to drip, wipe off the residual electrolyte on the surface of the aluminum clamp with dust-free paper. The weight is recorded as m1. Then, use an automatic press to apply 500N-3000N of pressure on both sides of the clamp (simulating the state of the battery cell in the battery pack). Hold for 3 minutes and weigh the weight, recorded as m2. Calculate the liquid retention rate of the negative electrode composite current collector according to the following formula:

[0188] in, θ is the liquid retention rate of the negative electrode composite current collector, in %.

[0189] (2) Cycling performance test of battery cells At a constant temperature of 25°C, the battery was charged to 4.4V at a constant current of 1C, then charged at a constant voltage of 4.4V until the current dropped to 0.05C, and then discharged to 2.5V at a constant current of 1C. The first cycle discharge specific capacity (C d1 ); Repeat the charge and discharge until the 500th cycle, and the discharge capacity after 500 cycles is recorded as C dn .

[0190] Capacity retention rate (%) = discharge capacity after 500 cycles (C dn ) / first cycle discharge specific capacity (C d1 ).

[0191] (3) Determination of lithium deposition level of negative electrode After cycling the battery cell for 500 cycles according to the above-mentioned cycling method, the battery cell was disassembled, and the positive and negative electrode sheets were further separated to observe the lithium deposition in the bending area and the middle area of ​​the negative electrode sheet. The judgment criteria are shown in Table 1.

[0192] Table 1

[0193] Table 2 shows 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 500-cycle capacity retention rate of the battery cell, and the lithium plating level.

[0194] Table 2

[0195] It can be seen from Examples 1-10 and Comparative Examples 1-2 that Figure 7 The structure of A3 has a tributary. When the electrolyte flows out of the organic support layer into the battery cell, the liquid vortex formed by the arc portion of the tributary severely hinders the outflow of the electrolyte, thereby making the organic support layer have a better liquid retention capacity. However, when the angle β is too small, the liquid vortex formed may not be large, and the effect of hindering liquid outflow is not obvious. Therefore, the liquid retention rate of the negative electrode composite current collector of Example 8 is reduced compared with the case with β of 45°. However, when β is too large, the angle at which the straight portion of the tributary intersects the main channel is too large, so the electrolyte rarely flows through the tributary channel when flowing out, and the effect of hindering liquid outflow is also not obvious. Therefore, the liquid retention rate of the negative electrode composite current collector of Example 10 is also reduced compared with the case with β of 45°.

[0196] For the adoption Figure 6 For the embodiment of the A2 structure, when y is 5 μm, as x increases, more electrolyte can enter the middle area of ​​the organic support layer, so the corresponding negative electrode composite current collector has a higher liquid retention rate; when y is 10 μm and x is 20 μm, compared with the case where x is 20 μm and y is 5 μm, because y is larger, it is conducive to the entry of the electrolyte, and the liquid retention rate of the negative electrode composite current collector is higher; and when x is 30 μm and y is 10 μm, compared with the case where x is 20 μm and y is 10 μm, it may be because the inflow of the electrolyte is not increased too much, and the liquid retention rate of the negative electrode composite current collector is not much different; but when y is increased to 15 μm, the hindering effect on the outflow of the electrolyte is greatly weakened, and the liquid retention rate of the negative electrode composite current collector is lower.

[0197] From the test results in Table 2, we can also see 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 ability, so that the battery monomer formed by it also has excellent cycle performance. The deep-seated reason is that the increase in the liquid retention rate of the negative electrode composite current collector effectively improves the wetting state of the electrolyte in the middle area of ​​the negative electrode, thereby effectively improving the lithium plating in the middle area.

[0198] It should be noted that the present disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solution of the present disclosure, embodiments having substantially the same structure as the technical concept and exerting the same effects are all included in the technical scope of the present disclosure. In addition, within the scope of the present disclosure, various modifications that can be conceived by those skilled in the art to the embodiments, and other methods constructed by combining some of the constituent elements in the embodiments are also included in the scope of the present disclosure.

Claims

1. A battery cell comprising an electrode assembly, wherein the electrode assembly comprises a composite current collector, characterized in that: The composite current collector comprises an organic support layer and a metal layer located on at least one side of the organic support layer; the metal layer has a porous structure; The organic support layer includes a middle area and an edge area located around the middle area. The edge area of ​​the organic support layer is provided with at least one channel connected to the middle area. The sidewall of the channel is provided with a blocking portion. The blocking portion is configured to allow the fluid in the channel to flow toward the middle area at a faster speed than that of the fluid flowing toward the edge area.

2. The battery cell according to claim 1, wherein: The porosity of the middle region of the organic supporting layer is greater than the porosity of the edge region of the organic supporting layer.

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

4. The battery cell according to claim 1, wherein: The channel has a depth direction, and the dimension of the depth direction is the vertical distance between the first end of the channel 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 a plurality of channels communicating with the middle region, and the distance between two adjacent channels is 500 μm-1 mm.

5. The battery cell according to claim 1, characterized in that The channel is located in 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 located in the same plane, and the plane formed by the width direction and the height direction is perpendicular to the plane where the organic support layer is located.

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

7. The battery cell according to claim 1, characterized in that The blocking portion includes a plurality of obstruction mechanisms disposed obliquely, the obstruction mechanisms being disposed protruding from the side wall, the obstruction mechanisms being rod-shaped or plate-shaped, the obstruction mechanisms having a first end connected to the side wall and a second end protruding from the side wall and disposed obliquely; the first end of the same obstruction mechanism being disposed away from the middle area relative to the second end, and the obstruction mechanism meeting one or more of the following conditions (1)-(3): (1) The inclination angle α of the obstruction mechanism is 30°-60°; (2) The obstruction mechanism is provided on both of the two opposite side walls of the channel, and the vertical distance x between the first ends of the obstruction mechanisms on the two side walls is 10 μm-30 μm; the vertical distance y between the second ends of the obstruction mechanisms on the two side walls is 5 μm-15 μm; (3) A plurality of the obstruction mechanisms are arranged in sequence on the same side wall, the distance z between the first ends of the obstruction mechanisms adjacent to each other on the same side wall and exposed in the channel is 90 μm-110 μm, and the shortest distance s between the first ends of two adjacent obstruction mechanisms on the same side wall is 45 μm-55 μm.

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

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 3 μm-10 μm.

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

11. A method for preparing a composite current collector, characterized in that: include: Providing an organic support layer that has undergone a stretching process, the organic support layer comprising a middle region and edge regions located around the middle region, the edge regions of the organic support layer being provided with at least one channel communicating with the middle region, the sidewalls of the channel being provided with blocking portions, the blocking portions being configured to cause a fluid in the channel to flow toward the middle region at a greater speed than that flowing toward the edge regions; A metal layer is provided on at least one side 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: The invention comprises a plurality of battery cells according to any one of claims 1 to 10.

13. An electrical device, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 10 or the battery device according to claim 12.

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