CN113991121A

CN113991121A - Positive electrode current collector and preparation method thereof, positive electrode sheet, battery cell and battery

Info

Publication number: CN113991121A
Application number: CN202010009329.XA
Authority: CN
Inventors: 张芹
Original assignee: Shenzhen Haihong New Energy Technology Co ltd
Current assignee: Xiamen Haichen New Energy Technology Co Ltd
Priority date: 2020-01-03
Filing date: 2020-01-03
Publication date: 2022-01-28

Abstract

The present application provides a positive electrode current collector, a preparation method thereof, a positive electrode sheet, a battery core and a battery, and relates to the technical field of battery electrode sheets. The positive electrode current collector includes a base film and a functional layer disposed on the surface of the base film, and the first functional layer includes an adhesive layer, a current conducting layer and a protective layer that are sequentially stacked and disposed on the first surface. The first functional layer is divided into a first functional segment and a second functional segment, and the thickness of the first functional segment is greater than that of the second functional segment. The surface of the second functional layer is a coating area, and the structure enables the coating area to coat more active materials, thereby increasing the energy density of the positive electrode current collector. The first functional layer includes a tab segment, and a first coating segment is provided between the tab segment and the first coating segment and the second functional segment, so that the thickness of the first coating segment is equal to the thickness of the tab segment. By increasing the thickness of the functional layer at the connection between the coating section and the tab section, the structure improves the electrical conductivity and current conductivity at the connection between the coating section and the tab area, and improves the comprehensive flow-through capability of the positive electrode current collector.

Description

Positive current collector and preparation method thereof, positive plate, battery cell and battery

Technical Field

The application relates to the technical field of battery pole pieces, in particular to a positive pole current collector and a preparation method thereof, a positive pole piece, a battery core and a battery.

Background

The current collector serves as an important component of the lithium ion battery, and plays a role in supporting active substances and conducting current. The positive current collector generally includes a membrane segment coated with a positive active material and a tab segment welded to a cap. The current foil of the positive current collector is of the same thickness, and the structure has the problems of material waste and high cost. Research reports that the thickness of a membrane area is reduced to reduce the cost, but the structure has the problems of reduced conductivity and reduced flow conductivity.

Disclosure of Invention

The application aims to provide a positive current collector, a preparation method thereof, a positive plate, an electric core and a battery, so as to solve the technical problems of low conductivity and low flow conductivity of the positive current collector.

In a first aspect, an embodiment of the present application provides a positive electrode current collector, including: the base film has first surface and the second surface that sets up back to back, and the first surface is equipped with first functional layer, and the second surface is equipped with the second functional layer. The first functional layer comprises an adhesive layer, a flow guide layer and a protective layer which are sequentially stacked, and the adhesive layer is arranged on the first surface. The first functional layer is divided into a first functional section and a second functional section in the direction parallel to the first surface, and the thickness of the first functional section is larger than that of the second functional section. The first functional section comprises a first coating section and a tab section, the surface of the first coating section is used for coating materials, the surface of the tab section is used for being connected with a tab, and the first coating section is arranged between the tab section and the second functional section.

The positive current collector adopts functional layers with different thicknesses, so that the thickness of the second functional layer is smaller than that of the first functional layer. The surface of the second functional layer is a coating area, and the structure enables the coating area to be coated with more active substances, so that the energy density of the positive current collector is improved. The first functional layer comprises a pole lug section, and the surface of the pole lug section is a pole lug area and is used for being connected with a pole lug. And a first coating section is arranged between the tab section and the second functional section, and the thickness of the first coating section is equal to that of the tab section. The structure improves the conductivity and the flow conductivity of the joint of the coating area and the lug area by increasing the thickness of the functional layer of the joint of the coating area and the lug area, and improves the comprehensive overcurrent capacity of the positive current collector.

In one possible implementation, the ratio of the thickness of the first functional segment to the thickness of the second functional segment is (5-25): (1-15). Optionally, the thickness of the first functional segment is 500nm-2500nm, and the thickness of the second functional segment is 100nm-1500 nm.

The thickness of first functional section and the thickness influence the conductivity between utmost point ear district and the coating district of second functional section, through a large amount of experimental study, when the thickness of first functional section and the thickness ratio of second functional section in above-mentioned within range, can guarantee the conductivity in utmost point ear district, can improve the conductivity in coating district by a great extent.

In one possible implementation, the surface of the first coated segment has a dimension in a direction parallel to the first surface of 0.5nm to 25 nm.

The first coating section is the thickening department in coating district, and when the thickening width of first coating section was above-mentioned range value, can better improve the current capacity of anodal mass flow body.

In one possible implementation, the second functional segment includes a second coating segment and a third coating segment, the second coating segment is disposed between the first coating segment and the third coating segment, and the thickness of the second coating segment is gradually reduced from the first coating segment to the third coating segment.

The second coating section is connected with the first coating section, and the thickness of the first coating section and the thickness change of the second coating section are gradually reduced by the structure, so that the flow conductivity of the second functional section and the first functional section is improved, and further the comprehensive overcurrent capacity of the functional layer is improved. Meanwhile, the structure avoids the film surface defects of dead wrinkles and bulging force caused by different thicknesses of the functional layers.

In one possible implementation, the surface of the second coating section is a plane or a curved surface. Optionally, the surface of the second coating section and the surface of the third coating section are both planar, and the surface of the second coating section and the surface of the third coating section form an included angle of 1-50 degrees.

The surface of the second coating section can be adjusted in surface shape as required, so that the positive current collector is not affected by bending and bending in actual application.

In a possible implementation manner, the flow guide layer comprises metal layers and reinforcing layers which are alternately stacked, the thickness of each metal layer is 20-1500nm, the number of the layers is 2-50, the thickness of each reinforcing layer is 2-50nm, and the number of the layers is 1-49. In one possible implementation, the thickness of the base film is 1.2 μm to 12 μm, the thickness of the adhesive layer is 2 to 50nm, and the thickness of the protective layer is 2 to 50 nm.

The metal layer sets up with the alternating stromatolite of back up coat in above-mentioned layer thickness within range, can guarantee the water conservancy diversion ability on water conservancy diversion layer by great degree, and water conservancy diversion layer has better steadiness simultaneously. Base film, adhesive linkage, water conservancy diversion layer and protective layer are in above-mentioned thickness within range, and the adhesive linkage can make water conservancy diversion layer and base film be connected firmly for anodal mass flow body has better peel strength.

In one possible implementation, the structure of the second functional layer is the same as the structure of the first functional layer, and the second functional layer and the first functional layer are symmetrically arranged relative to the base film. The positive current collector with the structure has better conductivity and conductivity.

In one possible implementation mode, the metal layer is an aluminum layer, the reinforcing layer is a non-metal layer, and the composition of the reinforcing layer is AlO_xWherein x is more than or equal to 1 and less than or equal to 1.5, the protective layer is a non-metal layer, and the protective layer contains AlO_xWherein x is more than or equal to 1 and less than or equal to 1.5. The positive current collector containing the aluminum layer has better conductivity and flow conductivity.

In a second aspect, a positive plate is provided, which includes the positive current collector and an active material, wherein the active material is disposed on the surfaces of the first coating section and the second functional section. This positive plate adopts the anodal mass flow body that this application provided, can coat more active material, improves the energy density of anodal mass flow body. And the thickness of the connecting part of the functional layer corresponding to the coating area of the positive current collector and the tab section is increased, so that the conductivity and the flow conductivity of the positive plate are further improved.

In a third aspect, a battery cell is provided, which includes a negative electrode plate, a diaphragm layer, a casing and the above positive electrode plate, where the negative electrode plate, the diaphragm layer and the positive electrode plate are disposed in the casing. The battery cell comprises the positive plate, so that the energy density of the battery cell can be improved by 0.5-2%.

In a fourth aspect, a battery is provided, which includes a casing, the above electrical core, an insulating member and a top cover assembly, wherein the electrical core is accommodated in the casing, the insulating member is disposed between the electrical core and the casing, and the top cover assembly covers the casing and is connected to the electrical core through a tab. The battery has higher electric capacity, enlarges the application range of the battery, and can be applied to equipment with larger electric quantity requirement.

In a fifth aspect, a preparation method of the above positive electrode current collector is provided, including: and forming adhesive layers on the first surface and the second surface of the base film, forming flow guide layers with different thicknesses on the adhesive layers, and forming a protective layer on the flow guide layers. The positive current collector with different thicknesses is obtained by the preparation method.

In one possible implementation manner, the flow guiding layer includes metal layers and reinforcing layers which are alternately stacked, and the forming step of the flow guiding layer includes: the method comprises the following steps: and coating perfluoropolyether oil on the surface of the bonding layer corresponding to the second functional segment, and then aluminizing the surface of the bonding layer. Optionally, the second functional segment comprises a second coating segment and a third coating segment, the second coating segment being disposed between the first functional segment and the third coating segment; and coating perfluoropolyether oil on the surfaces of the bonding layer corresponding to the first coating section and the second functional section to form a coating layer, wherein the thickness of the coating layer is gradually reduced from the surface of the bonding layer corresponding to the first coating section to the surface corresponding to the second functional section. Step two: and forming a reinforcing layer on the aluminum layer obtained in the last step. Step three: and continuously aluminizing the reinforcing layer obtained in the last step to form an aluminum layer, so as to obtain the flow guide layer with inconsistent thickness. Optionally, repeating the second step and the third step to form the reinforcing layer and the aluminum layer which are alternately stacked until the thickness of the current guiding layer reaches a predetermined value.

The method adopts the coating of perfluoropolyether oil to prevent the formation of an aluminum layer and obtain the diversion layer with inconsistent thickness.

In one possible implementation manner, the flow guiding layer includes metal layers and reinforcing layers which are alternately stacked, and the forming step of the flow guiding layer includes: the method comprises the following steps: and arranging a water-cooling baffle plate between the surface of the bonding layer corresponding to the second functional section and the evaporation source, wherein the water-cooling baffle plate is provided with a plurality of through holes for steam to pass through, the arrangement density of the through holes is gradually reduced along the direction from the first functional section to the second functional section, and the surface of the bonding layer is plated with aluminum by adopting an evaporation method. Step two: and forming a reinforcing layer on the aluminum layer obtained in the last step. Step three: and (3) forming an aluminum layer on the reinforcing layer obtained in the previous step by adopting the evaporation method in the first step to obtain the flow guide layer with inconsistent thickness. Optionally, repeating the second step and the third step to form the reinforcing layer and the aluminum layer which are alternately stacked until the thickness of the current guiding layer reaches a predetermined value.

According to the method, the water-cooling baffle is adopted, the structure of the water-cooling baffle is improved, and the flow guide layers with different thicknesses can be obtained through evaporation.

In one possible implementation, the step of forming a reinforcing layer on the aluminum layer includes: placing the aluminizer with the outermost layer of the aluminum layer in an environment with the humidity of less than 50% and standing for 46-50h to form a reinforcing layer on the aluminum layer; or ionizing argon and oxygen by adopting plasma equipment to clean and oxidize the surface of the aluminum layer so as to form a reinforcing layer on the aluminum layer.

According to the method, the metal oxide is obtained by oxidizing the metal layer, so that the reinforcing layer is formed, and the reinforcing layer and the metal layer are strong in connecting force, so that the flow guide layer is high in stability.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a schematic structural diagram of a positive electrode current collector provided in an embodiment of the present application;

fig. 2 is a schematic structural diagram of another state of a positive electrode current collector provided in an embodiment of the present application;

fig. 3 is a schematic structural diagram of a portion of a positive electrode current collector provided in an embodiment of the present application, where a layer thickness is unchanged;

fig. 4 is a schematic structural diagram of a positive electrode current collector partition provided in an embodiment of the present application;

fig. 5 is a schematic structural view of the positive electrode current collector in fig. 4 from another perspective;

fig. 6 is a schematic structural diagram of another positive electrode current collector provided in an embodiment of the present application;

fig. 7 is a structural schematic diagram of the positive electrode current collector in fig. 6 from another perspective;

fig. 8 is a schematic structural view of a plurality of positive electrode current collectors of fig. 6;

fig. 9 is a schematic structural diagram of a plurality of yet another positive electrode current collectors provided in this embodiment.

Icon: 100-positive current collector; 110-a base film; 111-a first surface; 112-a second surface; 120-a functional layer; 121 — a first functional layer; 122-a second functional layer; 130-an adhesive layer; 140-a flow guiding layer; 141-a metal layer; 143-reinforcement layer; 150-a protective layer; 210-a first functional segment; 211 — a first coating section; 212-first coating zone; 213-a tab section; 214-polar ear region; 220-two functional segments; 221-a second coating section; 222-a second coating zone; 223-a third coating section; 224-third coating zone.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, it should be noted that the terms "upper", "lower", "left", "right", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that are usually placed when products of the application are used, and are only for convenience of describing the present application and simplifying the description. The terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Some embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Referring to fig. 1 and fig. 2, fig. 1 is a schematic structural diagram of a positive electrode current collector 100 provided in this embodiment, and fig. 2 is a schematic structural diagram of another state of the positive electrode current collector 100 provided in this embodiment.

The present embodiment provides a positive electrode current collector 100, which is used in a cell of a lithium battery and collects and outputs current generated by active materials of the battery. The positive electrode collector 100 has a multi-layer structure including a base film 110 and a functional layer 120 disposed on the base film 110. In the embodiment of the present application, the material of the base film 110 may be ortho-phenylphenol (OPP), polyethylene terephthalate (PET), Polyimide (PI), polyphenylene sulfide (PPS), cast polypropylene (CPP), polyethylene naphthalate (PEN), polyvinyl chloride (PVC), and preferably, the material of the base film 110 is PET, PPS, or PEN. The base film 110 may be made of any material, or two or more materials to form a composite film. In some embodiments of the present application, the base film 110 is the base film 110. The base film 110 made of the above material has a light weight, a good tensile property, and a good adhesive strength with the functional layer 120. In some embodiments of the present application, the thickness of the base film 110 is 1.2 μm to 12 μm, wherein the thickness of the base film 110 may be 1.2 μm, 1.5 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, or 12 μm.

Referring to fig. 2, the top surface of the base film 110 is a first surface 111, and the bottom surface is a second surface 112. In the embodiment of the present application, the first surface 111 and the second surface 112 are both provided with the functional layer 120, and further, the first surface 111 is provided with the first functional layer 121, and the second surface 112 is provided with the second functional layer 122. In other embodiments of the present application, the first surface 111 or the second surface 112 of the base film 110 is provided with the functional layer 120, which is adjusted according to actual needs. In this embodiment, the first functional layer 121 and the second functional layer 122 have the same structure, and the first functional layer 121 and the second functional layer 122 are symmetrically disposed with respect to the base film 110. The first functional layer 121 will be described in detail below as an example.

Referring to fig. 1 and 2, the first functional layer 121 includes an adhesive layer 130, a flow guiding layer 140, and a protective layer 150, which are sequentially stacked, wherein the adhesive layer 130 is disposed on the first surface 111. Referring to fig. 3, fig. 3 is a schematic structural view of a portion of the positive electrode current collector 100 where the thickness of the layer is not changed. The current guiding layer 140 includes metal layers 141 and reinforcing layers 143 alternately stacked, and the dotted line segment in the drawing indicates an omitted multilayer structure. It is understood that the adhesive layer 130 of the first functional layer 121 is disposed on the first surface 111, the metal layer 141 is disposed on the adhesive layer 130, the reinforcing layer 143 is disposed on the metal layer 141, and the metal layer 141 is further disposed on the reinforcing layer 143, and the metal layer 141 and the reinforcing layer 143 are further alternately disposed according to actual requirements, such as adjusting the conductivity of the current guiding layer 140, so that the current guiding layer 140 has a layer structure in which the metal layer 141 and the reinforcing layer 143 are alternately stacked. A protective layer 150 is then disposed on the surface of the flow guiding layer 140. In the embodiment, the outermost layer of the guiding layer 140 is a metal layer 141, and the protective layer 150 is disposed on the outermost metal layer 141.

Fig. 1 is a schematic view of a minimum unit structure of a positive electrode current collector 100, and fig. 2 is a schematic view of a plurality of uncut positive electrode current collectors 100. In the process of preparing the positive current collector 100, the base film 110 has a continuous film structure, the adhesive layer 130, the flow guiding layer 140 and the protective layer 150 having a certain structure are sequentially formed on the base film 110, and then the film with a longer length is cut as required to obtain the positive current collector 100.

In some embodiments of the present application, the adhesion layer 130 is a non-metal coating, and the non-metal coating includes SiC and Si₃N₄、SiO_x(x is more than or equal to 1.5 and less than or equal to 2) and AlO_x(1. ltoreq. x. ltoreq.1.5). The non-metal bonding layer can be formed by directly plating the above compound on the base film 110 by electron beam evaporation or other methods, or by directly reacting metal vapor, an organic metal source, and an oxygen source such as oxygen or water by a method similar to Chemical Vapor Deposition (CVD), which is not limited in the present application. In some embodiments of the present application, the thickness of the adhesive layer 130 is 2-50nm, and the adhesive layer 1 of the structure30 can firmly connect the base film 110, the flow guiding layer 140 and the protective layer 150, and the service performance of the positive current collector 100 is greatly ensured. Optionally, when the bonding layer is AlO_x(x is more than or equal to 1 and less than or equal to 1.5), the thickness of the bonding layer 130 is 8-20 nm; when the bonding layer is SiO_x(x is more than or equal to 1.5 and less than or equal to 2), the thickness of the adhesive layer 130 is 10-40 nm. Alternatively, the adhesive layer 130 may have a thickness of 2nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, or 50 nm.

The conventional positive electrode current collector 100 is generally an aluminum foil, and in the embodiment of the present invention, the metal layer 141 in the positive electrode current collector 100 is an aluminum layer or an aluminum alloy. In some embodiments of the present application, the thickness of the metal layer 141 is 20 to 1500nm, optionally, the thickness of the metal layer 141 is 20 to 1000nm, and further, the thickness of the metal layer 141 may be 20nm, 100nm, 200nm, 500nm, 700nm, 800nm, 1000nm, 1200nm, 1300nm, or 1500 nm.

The reinforcing layer 143 in this application is a dense non-metallic layer 141 with a composition of metal oxide. In some embodiments of the present application, the reinforcement layer 143 is AlO_x(x is more than or equal to 1 and less than or equal to 1.5). The thickness of the reinforcing layer 143 is 2-50nm, and optionally, the thickness of the reinforcing layer 143 may be 3-6nm, or 2nm, 5nm, 10nm, 20nm, 30nm, 40nm, or 50 nm. The reinforcing layer 143 in this application can be prepared by evaporation or static curing. In the present application, the metal layer 141 and the reinforcing layer 143 constitute the flow guiding layer 140, and within the thickness range of the metal layer 141 and the reinforcing layer 143, the number of the metal layer 141 may be 2 to 50, and the number of the reinforcing layer 143 may be 1 to 49, that is, the number of the metal layer 141 is one more than the number of the reinforcing layer 143.

The protective layer 150 is disposed on the outermost layer of the positive electrode collector 100 in order to prevent the metal layer 141 from being oxidized, and the protective layer 150 is an anti-oxidation layer. In some embodiments of the present application, the protection layer 150 is the nonmetal layer 141 or the metal layer 141, when the protection layer 150 is the metal layer 141, the metal may be Ni, and when the protection layer 150 is the nonmetal layer 141, the nonmetal may be SiC, Si₃N₄、SiO_x(x is more than or equal to 1.5 and less than or equal to 2) or AlO_x(x is more than or equal to 1 and less than or equal to 1.5). The thickness of the protective layer 150 is 2 to 50nm, and optionally, the thickness of the protective layer 150 may be 3 to 12nm, 2nm, 5nm, 10nm, or more,20nm, 30nm, 40nm or 50 nm.

The current collector is of an equal-thickness structure, and the inventor of the application finds that in practical application, because the area coated with the active substance has low requirements on the conductive capability, and in order to ensure the conductive capability of the area connected with the tab, the thickness of the area coated with the active substance is larger, the conductive capability is excessive, materials are wasted, and the cost is increased.

The application provides that the design of unequal thickness is carried out to positive pole mass flow body 100 for the thickness of the functional layer 120 that the utmost point ear district 214 corresponds is greater than the thickness of the functional layer 120 that the coating district corresponds, on the basis of guaranteeing the current capacity of positive pole mass flow body 100, reduces the thickness of the functional layer 120 that the coating district corresponds, increases the volume of the active material who coats on the coating district, improves the energy density that contains this positive pole mass flow body 100's electric core, makes the cost reduction of positive pole mass flow body 100 3-30%.

Referring to fig. 4, fig. 4 is a schematic structural diagram of the positive electrode current collector 100 according to the present application. In the embodiment of the present application, the first functional layer 121 is divided into a first functional segment 210 and a second functional segment 220 in a direction parallel to the first surface 111, and the thickness of the first functional segment 210 is greater than that of the second functional segment 220. Further, in order to ensure the electric conductivity of the tab region 214 and to increase the electric conductivity of the coating region to a greater extent, the ratio of the thickness of the first functional segment 210 to the thickness of the second functional segment 220 is (5-25): (1-15). In some embodiments of the present application, the first functional segment 210 has a thickness of 500nm to 2500nm, and the second functional segment 220 has a thickness of 100nm to 1500 nm. Alternatively, the first functional segment 210 has a thickness of 500nm, 1000nm, 1500nm, 2000nm, 2300nm or 2500nm and the second functional segment 220 has a thickness of 100nm, 500nm, 800nm, 1000nm, 1200nm or 1500 nm.

Referring to fig. 4 and 5, fig. 5 is a schematic structural view of the positive electrode current collector 100 in fig. 4 from another perspective. The first functional section 210 comprises a first coating section 211 and a tab section 213, and the surface of the tab section 213 is a tab area 214 for connecting with a tab; the surface of the first coating section 211 is a first coating region 212 for coating the active material, and the surface of the second functional section 220 is a portion of the coating region for coating the active material. The first coating section 211 is disposed between the tab section 213 and the second functional section 220, that is, the tab section 213, the first coating section 211 and the second functional section 220 are connected in sequence. Compared with the structure that the thickness of the functional layer 120 corresponding to the tab region 214 is greater than that of the functional layer 120 corresponding to the coating region, the structure increases the thickness of the functional layer 120 corresponding to the coating region on the side close to the tab region 214. Because the positive current collector 100 has higher requirement on the flow conductivity of the tab interface, the structure improves the conductivity and the flow conductivity of the joint of the coating area and the tab area 214, and avoids the short plate effect.

In order to further improve the current-carrying capacity of the positive electrode current collector 100, the surface of the first coating section 211 has a size of 0.5nm to 25nm in a direction parallel to the first surface 111. It can be understood that the width of the first coating region 212 is 0.5nm-25 nm. Alternatively, the width of the first coating region 212 is 1nm to 15 nm. The width of the first coating region 212 may be 0.5nm, 1nm, 5nm, 10nm, 15nm, 20nm, or 25 nm.

Referring to fig. 6 and 7, fig. 6 is another structural schematic diagram of the positive electrode current collector 100 of the present application, and fig. 7 is a structural schematic diagram of the positive electrode current collector 100 in fig. 6 from another perspective. The inventors of the present application have found that there is a certain limit to the current-conducting capability of the functional layer 120 having the above-mentioned structure, and in order to overcome this limit, the inventors of the present application have improved the structure of the second functional segment 220. In the embodiment of the present application, the second functional segment 220 includes a second coating segment 221 and a third coating segment 223, a surface of the second coating segment 221 is a second coating region 222, a surface of the third coating segment 223 is a third coating region 224, the second coating segment 221 is disposed between the first coating segment 211 and the third coating segment 223, and a thickness of the second coating segment 221 is gradually reduced from the first coating segment 211 to the third coating segment 223. Namely, the first coating section 211, the second coating section 221 and the third coating section 223 are sequentially connected to form a coating section, the first coating region 212, the second coating region 222 and the third coating region 224 form a coating region, the thickness of the first coating section 211 is equal to that of the tab region 214, the thickness of the third coating section 223 is equal to that of the second functional section 220, and the thickness of the second coating section 221 is gradually reduced from the first coating section 211 to the third coating section 223. The structure improves the contact area between the second functional section 220 and the first functional section 210, improves the flow conductivity of the joint of the second functional section 220 and the first functional section 210, and further improves the comprehensive overcurrent capacity of the functional layer 120. Meanwhile, the structure avoids the film surface defects of dead wrinkles and bulging force at different positions of the functional layer 120.

Further, the surface of the second coating section 221 is a plane or a curved surface, i.e., the second coating region 222 is a plane or a curved surface. Referring to fig. 6, in the embodiment of the present application, the surface of the first functional segment 210 is a plane, preferably, the surface of the second coating segment 221 forms an included angle α with the surface of the first functional segment 210, and when the included angle is 1 to 50 degrees, the current-carrying capacity of the functional layer 120 is better, and optionally, the included angle is 1 to 30 degrees. Referring to fig. 6 and 8, fig. 8 is a schematic structural diagram of a plurality of positive electrode current collectors 100 in fig. 6. When the surfaces of the second coating segment 221 and the third coating segment 223 are both planar, the surface of the first functional layer 121 is stepped. Referring to fig. 9, fig. 9 is a schematic structural diagram illustrating a plurality of positive electrode current collectors 100 connected together. When the surfaces of the second coating section 221 and the third coating section 223 are both curved, the surface of the first functional layer 121 is waved. In other embodiments of the present application, the surface shape of the second coating section 221 and the surface shape of the third coating section 223 may be changed as needed, and the present application does not limit the same.

The positive current collector 100 provided by the application has the functional layer 120 with unequal thickness, the thickness of the second functional layer 122 is smaller than that of the first functional layer 121, and the thickness of the second coating section 221 and the third coating section 223 is smaller than that of the tab section 213, so that more active substances can be coated in the coating area, and the energy density of the positive current collector 100 is improved.

Further, a first coating section 211 is arranged between the tab section 213 and the second functional section 220, and the thickness of the first coating section 211 is equal to that of the tab section 213. By increasing the thickness of the functional layer 120 corresponding to the coated region, the conductivity and conductivity of the connection between the coated region and the tab region 214 are improved.

Furthermore, the thickness of the second coating segment 221 is gradually reduced from the first coating segment 211 to the third coating segment 223, so that the contact area between the second functional segment 220 and the first functional segment 210 is increased, the flow conductivity at the joint of the second functional segment 220 and the first functional segment 210 is increased, and further the comprehensive overcurrent capacity of the functional layer 120 is increased.

The application also provides a battery (not shown in the figure), which comprises a shell, a battery core, an insulating piece and a top cover assembly, wherein the battery core is contained in the shell, the insulating piece is arranged between the battery core and the shell, and the top cover assembly is covered on the shell and is connected with the battery core through a lug. The battery cell comprises a negative plate, a diaphragm layer, a shell and a positive plate, wherein the negative plate, the diaphragm layer and the positive plate are arranged in the shell. The positive electrode sheet includes a positive electrode collector 100 and active materials coated on the surfaces of the first coating section 211 and the second functional section 220. The positive current collector 100 can be coated with more active substances, so that the energy density of a battery core containing the positive plate can be improved by 0.5-2%, the battery has higher electric capacity, the application range of the battery is expanded, and the positive current collector can be applied to equipment with higher electric quantity demand.

The application also provides a preparation method of the positive current collector, which comprises the following steps: forming an adhesive layer on the first surface of the base film, forming a flow guide layer with inconsistent thickness on the adhesive layer, and forming a reinforcing layer on the flow guide layer. The method for producing the positive electrode current collector will be specifically described below.

And (5) preparing an adhesive layer.

The base film may be pretreated before preparing the adhesive layer, including: the first and second surfaces of the base film are corona treated. Then, an adhesive layer is formed on the surface of the base film by an evaporation method. The bonding layer is nonmetal, optional, SiC or Si is selected as nonmetal₃N₄、SiO_x(x is more than or equal to 1.5 and less than or equal to 2) and AlO_x(1. ltoreq. x. ltoreq.1.5).

In some embodiments of the present application, a method for forming an adhesive layer includes:

placing the corona or non-corona base film into a vacuum chamber of a single-sided or double-sided reciprocating vacuum coating machine, sealing the vacuum chamber, and gradually vacuumizing until the vacuum degree reaches 10^-4Pa-10^-1Pa, by means of an oxygen-introducing structure near the evaporation sourceAnd (3) introducing compressed oxygen or ozone, adjusting the ventilation quantity, the unreeling speed and the reeling speed, and evaporating raw materials by adopting an evaporation source to form an adhesive layer on the moving base film. In one practical example, the evaporation source adopts aluminum wire or ingot with purity not less than 99.9%, winding speed is set to 300-400m/min, wire feeding amount is set to 250-350mm/min, evaporated aluminum atom reacts with oxygen and forms a layer of AlO on the moving base film_x(x is more than or equal to 1 and less than or equal to 1.5) layers, namely the bonding layers, and the thickness of the layers is 2-50 nm. It should be noted that AlO formed in the examples of the present application_xThe value of x is determined according to whether the oxidation is complete, and when the oxidation of aluminum is complete, x is 1.5, and Al is obtained₂O₃When the aluminum oxidation is incomplete, x is more than or equal to 1 and less than 1.5.

Or placing the corona or non-corona base film into a vacuum chamber of a single-sided or double-sided reciprocating vacuum coating machine, sealing the vacuum chamber, and gradually vacuumizing until the vacuum degree reaches 10^-4Pa-10^-1And Pa, adopting an electron gun to accelerate electron bombardment to collide with evaporation raw materials, adjusting the unwinding speed, the winding speed and the evaporation capacity, absorbing heat and gasifying the raw materials, and forming a coating layer, namely a bonding layer, on the surface of the moving base film. In one practical example, the evaporation material is alumina, which is gasified through heat absorption to form AlO layer on the surface of the base film_x(x is more than or equal to 1 and less than or equal to 1.5) plating layer.

Or placing the corona or non-corona base film into a vacuum chamber of a single-sided or double-sided reciprocating vacuum coating machine, sealing the vacuum chamber, and gradually vacuumizing until the vacuum degree reaches 10^-4Pa-10^-1Pa, performing double-sided reciprocating high-efficiency film coating on the base film by utilizing magnetron sputtering. In an achievable embodiment, the target is high-purity alumina, the purity is more than or equal to 99.9 percent, the unwinding speed and the winding speed are adjusted, and sputtered alumina molecules form a layer of AlO on a moving film_x(x is more than or equal to 1 and less than or equal to 1.5), namely the bonding layer.

Or placing the corona or non-corona base film into a vacuum chamber of a single-sided or double-sided reciprocating vacuum coating machine, sealing the vacuum chamber, and gradually vacuumizing until the vacuum degree reaches 10^-4Pa-10^-1Pa, performing double-sided reciprocating high-efficiency film coating on the base film by utilizing magnetron sputtering. In a kind of can be realIn the present embodiment, the target material is high-purity aluminum with a purity of more than or equal to 99.9%, and high-purity oxygen is introduced into the sputtering path to react the aluminum with the oxygen to generate AlO_x(x is more than or equal to 1 and less than or equal to 1.5) and is deposited on the base film, namely the bonding layer.

Or, the corona or non-corona base film is placed into a continuous chemical vapor deposition device, trimethylaluminum or aluminum chloride is used as an aluminum source, oxygen, ozone, moisture or carbon dioxide is used as an oxygen source, the gas proportion, the winding speed and the unwinding speed are adjusted, and the gas is ionized to react and deposit an aluminum oxide layer, namely a bonding layer, on the base film.

And (4) preparing a flow guide layer. The diversion layer in this application includes a metal layer and a reinforcing layer, in some embodiments of this application, the metal layer is an aluminum layer, and the reinforcing layer is an oxide of aluminum, which is described below as an example.

In some embodiments of the present application, a perfluoropolyether oil that hinders aluminizing is selectively coated on the bonding layer, so that an aluminum layer is not easily formed on the bonding layer coated with the perfluoropolyether oil, and thus an aluminum layer with inconsistent thickness is obtained. Specifically, the method comprises the following steps:

the method comprises the following steps: and coating perfluoropolyether oil on the surfaces of the bonding layer corresponding to the first coating section and the second functional section to form a coating layer, wherein the thickness of the coating layer is gradually reduced from the surface of the bonding layer corresponding to the first coating section to the surface corresponding to the second functional section. Then aluminum is plated on the surface of the bonding layer, the position coated with the perfluoropolyether oil does not form an aluminum layer initially in the aluminum plating process, the perfluoropolyether oil gradually reduces to disappear along with the increase of the aluminum plating amount, and the aluminum layer begins to form on the surface of the bonding layer coated with the perfluoropolyether oil. The method combines the winding speed and the evaporation capacity of the base film to form the aluminum layer with certain structure and inconsistent thickness on the bonding layer.

Step two: and forming a reinforcing layer on the aluminum layer obtained in the last step. The previous step refers to the previous step, and in this step, refers to step one. The forming method of the reinforcing layer in the application comprises the following steps:

and placing the aluminizer with the outermost layer of the aluminum layer in an environment with the humidity of less than 50% for standing for 46-50h to form a reinforcing layer on the aluminum layer. The method is implemented byThe aluminum-coated layer reacts with oxygen in the environment to generate AlO_x(x is more than or equal to 1 and less than or equal to 1.5) to obtain the reinforcing layer.

Or ionizing argon and oxygen by adopting plasma equipment to clean and oxidize the surface of the aluminum layer so as to form a reinforcing layer on the aluminum layer. The method generates AlO by the oxidation of aluminum on the surface of an aluminum layer_x(x is more than or equal to 1 and less than or equal to 1.5) to obtain the reinforcing layer.

When the reinforcing layer is made of other materials, the reinforcing layer may be formed on the aluminum layer by a conventional technique in the art, such as evaporation, magnetron sputtering, or the like.

Step three: and continuously aluminizing the reinforcing layer obtained in the last step to form an aluminum layer, so as to obtain the flow guide layer with inconsistent thickness. And when the thickness of the aluminum layer formed before reaches the requirement, aluminum plating can be performed according to a normal process, and when the aluminum layer with inconsistent thickness needs to be formed continuously, perfluoropolyether oil is coated on the reinforced layer obtained in the last step, wherein the coating method is the same as the first step. After coating, the reinforcement layer coated with perfluoropolyether oil is aluminized. Wherein the perfluoropolyether oil can be replaced with other solutions having low surface dyne values.

It should be noted that, because the aluminum layer in the embodiment of the present application is a multilayer, the perfluoropolyether oil may be coated to obtain the aluminum layer with inconsistent thickness each time aluminum is plated, or the perfluoropolyether oil may be selectively coated, and the specific preparation process is adjusted according to actual needs, which is not limited in the present application. When preparing a plurality of aluminum layers and reinforcing layers, repeating the second step and the third step to form the reinforcing layers and the aluminum layers which are alternately laminated until the thickness of the flow guide layer reaches a preset value.

In some embodiments of the present application, a water-cooled baffle is used to control the amount of the bonding layer formed by the aluminum vapor at different positions, so as to obtain aluminum layers with inconsistent thickness. Specifically, the method comprises the following steps:

the method comprises the following steps: and arranging a water-cooling baffle plate between the surface of the bonding layer corresponding to the second functional section and the evaporation source, wherein the water-cooling baffle plate is provided with a plurality of through holes for steam to pass through, the arrangement density of the through holes is gradually reduced along the direction from the first functional section to the second functional section, and the surface of the bonding layer is plated with aluminum by adopting an evaporation method. Due to the action of the water-cooling baffle plate, the amount of aluminum deposited on the surface of the bonding layer is different, and an aluminum layer with a certain structure and inconsistent thickness is formed by combining the winding speed and the evaporation amount. It should be noted that the present application is not limited to the evaporation mechanism of the present application, and other structures of the evaporation mechanism of the present application have been described.

Step two: and forming a reinforcing layer on the aluminum layer obtained in the last step. The method of forming the reinforcing layer is the same as described above. And placing the aluminizer with the outermost layer of the aluminum layer in an environment with the humidity of less than 50% for standing for 46-50h to form a reinforcing layer on the aluminum layer. The method generates AlO by the reaction of the aluminum layer and oxygen in the environment_x(x is more than or equal to 1 and less than or equal to 1.5) to obtain the reinforcing layer. Or ionizing argon and oxygen by adopting plasma equipment to clean and oxidize the surface of the aluminum layer so as to form a reinforcing layer on the aluminum layer. The method generates AlO by the oxidation of aluminum on the surface of an aluminum layer_x(x is more than or equal to 1 and less than or equal to 1.5) to obtain the reinforcing layer.

Step three: and (3) forming an aluminum layer on the reinforcing layer obtained in the previous step by adopting the evaporation method in the first step to obtain the flow guide layer with inconsistent thickness.

It should be noted that the aluminum layer in the embodiment of the present application is a multilayer, a water-cooling baffle may be adopted to obtain aluminum layers with inconsistent thicknesses in each aluminum plating, the water-cooling baffle may also be selectively arranged, and the specific preparation process is adjusted according to actual needs, which is not limited in the present application. When preparing a plurality of aluminum layers and reinforcing layers, repeating the second step and the third step to form the reinforcing layers and the aluminum layers which are alternately laminated until the thickness of the flow guide layer reaches a preset value.

And (4) preparing a protective layer. The protective layer of the embodiment of the application can be a metal layer or a non-metal layer, and the protective layer made of corresponding materials is prepared on the flow guide layer according to different materials. In some embodiments of the present application, the passivation layer is AlO_x(x is more than or equal to 1 and less than or equal to 1.5). The preparation method comprises the following steps:

and (3) placing the film with the flow guide layer in a room temperature environment with the humidity of less than 50%, standing and curing for 46-50h, wherein a compact oxide layer, namely a protective layer with an anti-oxidation effect, is formed on the surface of the aluminizer due to the permeation of oxygen or a small amount of moisture in the air.

Or, the film with the flow guide layer is placed in a vacuum chamber of a single-side or double-side evaporation coating machine containing a plasma device, the vacuum chamber is sealed, and the vacuum chamber is gradually vacuumized until the vacuum degree reaches 10^-4-10^-1Pa, using plasma equipment to ionize argon and oxygen to clean and oxidize the surface of the aluminizer without opening an evaporation source to generate a layer of compact AlO_x(x is more than or equal to 1.4 and less than or equal to 1.5), namely the protective layer.

Or, the film with the flow guiding layer is put into a high-temperature ozone reaction device, the reaction temperature and the ozone content are adjusted, and the denser AlO is formed on the surface of the aluminizer_x(x is more than or equal to 1.4 and less than or equal to 1.5), namely the protective layer.

The features and properties of the present application are described in further detail below with reference to examples.

Example 1

The embodiment provides a positive current collector and a preparation method thereof, and the preparation method comprises the following steps:

s1, firstly, performing corona treatment on the surface of a base film to be coated, wherein the thickness of the base film is 12 microns, then placing a winding drum base film into a vacuum chamber of a vacuum coating machine, sealing the vacuum chamber, and gradually vacuumizing until the vacuum degree reaches 5 multiplied by 10^-2And Pa, introducing compressed oxygen by utilizing an oxygen introducing structure near the evaporation source, wherein the air introducing amount is 4000sccm and 3500 sccm. The evaporation source evaporation raw material is metal aluminum wire or aluminum ingot, the purity is more than or equal to 99.9 percent, the winding speed is set to 350m/min, the wire feeding amount is set to 300mm/min, and evaporated aluminum atoms react with oxygen to form a layer of Al on the moving film₂O₃The oxide layer, i.e. the adhesive layer, is about 10nm thick.

S2, placing the film with the bonding layer on the surface obtained in the step S1 into a vacuum chamber of a single-side or double-side reciprocating evaporation coating machine containing a plasma device, sealing the vacuum chamber, and gradually vacuumizing until the vacuum degree reaches 2 multiplied by 10^-2Pa, before entering the evaporation zone, ionizing argon by plasma equipment to clean the surface of the bonding layer, wherein the amount of the argon is 500 sccm. And (3) coating the perfluoropolyether oil on the surface of the bonding layer at a fixed point and a fixed width by using a coating device, wherein the thicknesses of the coating layers are the same.

Then the aluminum is put into an evaporation area, the aluminum with the purity of more than or equal to 99.9 percent is heated by adopting an evaporation mode, the winding speed is set to be 300m/min, the wire feeding amount is set to be 1100mm/min, the aluminum is continuously melted and evaporated in an evaporation mechanism, and an aluminum plating layer with inconsistent thickness, namely an aluminum metal plating layer, is formed on the surface of the bonding layer, and the thickness of the part with larger thickness of the aluminum metal plating layer is about 50-55 nm.

S3, placing the aluminizer obtained in the step S2 into a vacuum chamber of a single-side or double-side reciprocating evaporation coating machine containing a plasma device, sealing the vacuum chamber, and vacuumizing step by step until the vacuum degree reaches 2 multiplied by 10^-2Pa, before entering the evaporation area, ionizing argon and oxygen by using a plasma device to clean and oxidize the surface of the aluminized film, wherein the argon is 500sccm, the oxygen is 350sccm, and denser Al is generated on the surface of the aluminized metal layer₂O₃An oxide layer, i.e. a reinforcement layer, the thickness of which is about 4 nm.

Then the aluminum enters an evaporation area, the aluminum with the purity of more than or equal to 99.9 percent is heated by adopting an evaporation mode, the unwinding speed, the winding speed and the evaporation amount are adjusted, the aluminum is continuously melted and evaporated in an evaporation mechanism, and an aluminum-plated layer is formed on the surface of the bonding layer.

Repeating the step 40 times according to the design of single-sided and double-sided molding of the equipment to obtain the flow guide layer with the metal layer and the reinforcing layer alternately laminated, wherein the outermost layer of the flow guide layer is an aluminum layer.

S4, placing the aluminizer obtained in the step S3 in humidity<50 percent, standing and curing for 48 hours in a room temperature environment, and forming a layer of compact Al on the surface of the aluminizer due to the permeation of oxygen or a small amount of moisture in the air₂O₃An oxide layer, i.e. a protective layer, the thickness of which is about 3 nm.

The positive electrode current collector with different thicknesses is obtained through the steps, and the structure of the positive electrode current collector is shown in figure 1.

Example 2

The present embodiment provides a positive electrode current collector and a method for preparing the same, which are different from those of embodiment 1 only in that:

when the perfluoropolyether oil is coated in S2, the thickness of the coating layer is gradually reduced from the surface of the adhesive layer corresponding to the first coated segment to the surface corresponding to the second functional segment. After vapor deposition, aluminum plating layers with inconsistent thickness are formed on the surface of the bonding layer, and the thickness of the aluminum plating layers is gradually changed.

The positive electrode current collector with different thicknesses obtained in the embodiment has a structure shown in fig. 6.

Example 3

S2, placing the film with the bonding layer on the surface obtained in the step S1 into a vacuum chamber of a single-side or double-side reciprocating evaporation coating machine containing a plasma device, sealing the vacuum chamber, and gradually vacuumizing until the vacuum degree reaches 2 multiplied by 10^-2Pa, before entering the evaporation zone, ionizing argon by plasma equipment to clean the surface of the bonding layer, wherein the amount of the argon is 600 sccm.

And then entering an evaporation area, and arranging a water-cooling baffle plate between the bonding layer and the evaporation source to shield the surface of the bonding layer corresponding to the second functional section. The water-cooling baffle in this embodiment is equipped with a plurality of through-holes that supply steam to pass, and the row of a plurality of through-holes is established density and is evenly set up. Heating aluminum with the purity of more than or equal to 99.9% in an evaporation mode, setting the winding speed to be 380m/min, setting the wire feeding amount to be 900mm/min, continuously melting and evaporating the aluminum in an evaporation mechanism, and forming an aluminum plating layer with inconsistent thickness on the surface of the bonding layer, namely an aluminum metal plating layer, wherein the thickness of the aluminum metal plating layer is about 60-65 nm.

S3, placing the aluminizer obtained in the step S2 into a single-sided or double-sided reciprocating steaming device containing a plasma deviceIn a vacuum chamber of a coating machine, the vacuum chamber is sealed and is gradually vacuumized until the vacuum degree reaches 2 multiplied by 10^-2Pa, before entering the evaporation area, ionizing argon and oxygen by a plasma device to clean and oxidize the surface of the aluminized film, wherein the argon is 600sccm, the oxygen is 400sccm, and a compact Al layer is generated on the surface of the aluminized metal layer₂O₃An oxide layer, i.e. a reinforcement layer, the thickness of which is about 4 nm.

Then the aluminum enters an evaporation area, the water-cooling baffle is arranged between the bonding layer and the evaporation source, the aluminum with the purity of more than or equal to 99.9 percent is heated in an evaporation mode, the unwinding speed, the winding speed and the evaporation amount are adjusted, the aluminum is continuously melted and evaporated in an evaporation mechanism, and an aluminum coating layer is formed on the surface of the bonding layer.

Repeating the step 30 times according to the design of single-sided and double-sided molding of the equipment to obtain the flow guide layer with the metal layer and the reinforcing layer alternately laminated, wherein the outermost layer of the flow guide layer is an aluminum layer.

S4, placing the aluminizer obtained in the step S3 into a vacuum chamber of a single-side or double-side evaporation coating machine containing a plasma device, sealing the vacuum chamber, and vacuumizing step by step until the vacuum degree reaches 5 multiplied by 10^-3-5×10^-2Pa, using plasma equipment to ionize argon and oxygen to clean and oxidize the surface of the aluminizer without opening an evaporation source to generate a compact layer of Al₂O₃An oxide layer, i.e. an anti-oxidation layer, having a thickness of about 4 nm.

The anode current collector with different thicknesses is obtained through the steps, and the thickness of the obtained aluminum layer is consistent due to the fact that the through holes of the water-cooling baffle are uniformly formed. The positive electrode current collector had the same structure as that of example 1, but had a different thickness.

Example 4

The present embodiment provides a positive electrode current collector and a method for preparing the same, which are different from those of embodiment 3 only in that:

in S2, a water-cooled baffle is provided between the adhesive layer and the evaporation source so that the surface of the adhesive layer corresponding to the second functional segment is shielded by the water-cooled baffle. The water-cooling baffle in this embodiment is equipped with a plurality of through-holes that supply steam to pass, and the row of a plurality of through-holes establishes the density and reduces according to setting gradually. In the process of evaporating metal aluminum on the bonding layer, the thickness of the formed aluminum layer is inconsistent and the aluminum layer with gradually changed thickness is obtained due to different arrangement densities of the through holes of the water-cooling baffle.

The positive electrode current collector with different thicknesses obtained in this example has the same structure as the positive electrode current collector of example 2, but different specific thicknesses, as shown in fig. 6.

Example 5

The present embodiment provides a positive electrode current collector and a method for preparing the same, which are different from those of embodiment 3 only in that: the thickness of the base film used in this example was 6 μm.

The thickness of the base film adopted in the embodiment is reduced compared with that of the embodiment 3, so that the mechanical property of the positive electrode current collector is changed.

Example 6

s1, firstly, performing corona treatment on the surface of a base film to be coated, wherein the thickness of the base film is 12 microns, then placing a winding drum base film into a vacuum chamber of a vacuum coating machine, sealing the vacuum chamber, and gradually vacuumizing until the vacuum degree reaches 5 multiplied by 10^-2And Pa, adopting an electron gun to accelerate electron bombardment to collide with evaporated alumina raw materials, setting the purity to be more than or equal to 99.9%, setting the winding speed to be 350m/min, absorbing heat and gasifying the raw materials, and forming a coating layer, namely a bonding layer, on the surface of the moving base film, wherein the thickness of the coating layer is about 10 nm.

Example 7

s4, placing the aluminizer obtained in the step S3 into a high-temperature ozone reaction device, adjusting the reaction temperature and the ozone content, and forming a layer of compact Al on the surface of the aluminizer₂O₃An oxide layer, i.e. a protective layer, the thickness of which is about 4 nm.

Comparative example 1

the aluminum layers obtained by evaporation without coating perfluoropolyether oil in S2 and S3 were uniform in thickness. The positive current collector obtained in this embodiment has an equal thickness structure.

Comparative example 2

This comparative example provides a common positive current collector.

Test example 1

Conducting performance tests are respectively carried out on the first functional section and the second functional section of the positive current collector provided in the examples 1-7 and the comparative examples 1-2 by adopting a sheet resistance meter and a balance, and the method comprises the following steps:

testing by using a sheet resistance instrument:

1. the entire width sample was tested from the edge using a four-wire sheet resistance tester, and the entire width sheet resistance was measured in the Transverse (TD) direction.

2. And (3) the probe of the sheet resistance meter is required to be vertical to the membrane surface and pressed to the bottom, and the numerical value is stable and recorded when being displayed.

3. The same method tests three rows in the Machine Direction (MD) and records the data.

Balance conductivity test:

1. the entire width of the sample was taken, an a4 pad was placed on the flattened surface under the film, and the sample was cut with a rotary cutter, and the TD direction was equally divided into 10 samples.

2. The balance is calibrated first to see if the balance level is in the middle equilibrium position, showing that the weight returns to zero.

3. And (5) placing the sample on a balance platform, and recording after the balance displays stable numerical values.

4. And (3) calculating the thickness after testing the product quality: (finished mass-raw film mass)/sample density/sample area 100.

5. And (3) calculating the conductivity: thickness (nm) sheet resistance (m Ω).

And (3) adopting a high-speed rail tensile machine to test the mechanical properties:

1. a whole width sample is taken in the TD direction and the MD direction respectively, and a strip sample with the width of 15mm and the length of 200mm is taken.

2. Setting the initial distance of a tensile machine to be 50mm, and testing the speed to be 50 mm/min; and (4) using a tension machine clamp to clamp the strip sample evenly and tightly at two ends of the sample for testing.

3. TD, MD samples were tested and recorded using this method.

The test results are as follows:

TABLE 1 first functional segment Performance test results

TABLE 2 second functional segment Performance test results

As can be seen from tables 1 and 2, the positive electrode current collectors provided in examples 1 to 4 and examples 6 to 7 of the present application have better electrical and mechanical properties than those of comparative example 1 and comparative example 2. Example 5 affects the mechanical properties of the positive electrode current collector due to the thin base film. The positive electrode current collectors provided in embodiments 1 to 4 and 6 to 7 of the present application are divided into two functional segments, where the sheet resistance of the first functional segment is 40 to 50m Ω, and the resistivity is 3.5 to 4.5 × 10^-8Omega.m. The transverse tensile strength is about 185-220MPa, and the longitudinal tensile strength is about 190-230 MPa. The second functional segments of examples 1-4 and 6-7 had sheet resistances of 75-80m Ω and resistivities of 3.5-6.0X 10^-8Omega-m, the transverse tensile strength is about 210-230MPa, the longitudinal tensile strength is about 190-260MPa, the transverse fracture elongation is about 94% -110%, the longitudinal fracture elongation is about 95-130%, and the dyne value of the positive electrode current collector is about 56.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A positive electrode current collector, characterized in that, comprising: a base film and a functional layer arranged on the surface of the base film, the base film has a first surface and a second surface arranged opposite to each other, the first surface The surface is provided with a first functional layer, and the second surface is provided with a second functional layer;

The first functional layer includes an adhesive layer, a flow guiding layer and a protective layer that are stacked in sequence, and the adhesive layer is arranged on the first surface;

The first functional layer is divided into a first functional segment and a second functional segment in a direction parallel to the first surface, and the thickness of the first functional segment is greater than the thickness of the second functional segment;

The first functional section includes a first coating section and a tab section, the surface of the first coating section is used for coating material, the surface of the tab section is used for connecting with the tab, the first The coating segment is arranged between the tab segment and the second functional segment.

2 . The positive electrode current collector according to claim 1 , wherein the ratio of the thickness of the first functional segment to the thickness of the second functional segment is (5-25): (1-15); 2 .

Optionally, the thickness of the first functional segment is 500 nm-2500 nm, and the thickness of the second functional segment is 100 nm-1500 nm.

3 . The positive electrode current collector according to claim 1 , wherein the size of the surface of the first coating section in a direction parallel to the first surface is 0.5 nm-25 nm. 4 .

4. The positive electrode current collector according to any one of claims 1 to 3, wherein the second functional section comprises a second coating section and a third coating section, and the second coating section is provided in Between the first coating section and the third coating section, the thickness of the second coating section gradually decreases from the first coating section to the third coating section.

5. The positive electrode current collector according to claim 4, wherein the surface of the second coating section is a plane or a curved surface;

Optionally, the surface of the second coating section and the surface of the third coating section are both flat, and the surface of the second coating section and the surface of the third coating section form an included angle, The included angle is 1-50 degrees.

6 . The positive electrode current collector according to claim 1 , wherein the current conducting layer comprises a metal layer and a reinforcement layer which are alternately stacked, the thickness of the metal layer is 20-1500nm, and the number of layers is 2- 50 layers, the thickness of the reinforcement layer is 2-50nm, and the number of layers is 1-49 layers.

7 . The positive electrode current collector according to claim 6 , wherein the thickness of the base film is 1.2 μm-12 μm, the thickness of the adhesive layer is 2-50 nm, and the thickness of the protective layer is 2-50 nm. 8 . 50nm.

8 . The positive electrode current collector according to claim 1 , wherein the structure of the second functional layer is the same as that of the first functional layer, and the second functional layer is the same as the structure of the first functional layer. 9 . The first functional layer is symmetrically arranged relative to the base film.

9 . The positive electrode current collector according to claim 6 , wherein the metal layer is an aluminum layer, the reinforcing layer is a non-metallic layer, and the composition of the reinforcing layer is AlO _x , wherein 1≤x≤ 1.5. The protective layer is a non-metallic layer, and the composition of the protective layer is AlO _x , where 1≤x≤1.5.

10. A positive electrode sheet, characterized in that, comprising:

The positive electrode current collector of any one of claims 1 to 9, and

Active substances, the active substances are arranged on the surfaces of the first coating section and the second functional section.

11. A battery cell, characterized in that it comprises a negative electrode sheet, a diaphragm layer, a casing and the positive electrode sheet according to claim 10, wherein the negative electrode sheet, the diaphragm layer and the positive electrode sheet are arranged in the casing .

12 . A battery, characterized in that it comprises a casing, the battery cell according to claim 11 , an insulating member and a top cover assembly, the battery core is accommodated in the interior of the casing, and the insulating member is disposed in the Between the battery core and the casing, the top cover assembly is covered on the casing, and is connected to the battery core through tabs.

13. A method for preparing a positive electrode current collector according to any one of claims 1 to 9, characterized in that, comprising: forming the adhesive layer on the first surface and the second surface of the base film, The flow-guiding layer with different thicknesses is formed on the adhesive layer, and the protective layer is formed on the flow-guiding layer.

14 . The method for preparing a positive electrode current collector according to claim 13 , wherein the conducting layer comprises metal layers and reinforcing layers which are alternately stacked and arranged, and the forming step of the conducting layer comprises: 14 .

Step 1: Coating perfluoropolyether oil on the surface of the adhesive layer corresponding to the second functional segment, and then coating the surface of the adhesive layer with aluminum;

Optionally, the second functional section includes a second coating section and a third coating section, the second coating section is arranged between the first functional section and the third coating section; in The surface of the adhesive layer corresponding to the first coating section and the second functional section is coated with perfluoropolyether oil to form a coating, so that the thickness of the coating is determined by the thickness of the adhesive layer. The surface corresponding to the first coating section gradually becomes smaller toward the surface corresponding to the second functional section;

Step 2: forming a reinforcement layer on the aluminum layer obtained in the previous step;

Step 3: Continue to aluminize on the reinforcement layer obtained in the previous step to form an aluminum layer, so as to obtain a diversion layer with inconsistent thickness;

Optionally, steps 2 and 3 are repeated to form the reinforcement layer and the aluminum layer alternately stacked, until the thickness of the flow guiding layer reaches a predetermined value.

15 . The method for preparing a positive electrode current collector according to claim 13 , wherein the conducting layer comprises metal layers and reinforcing layers which are alternately stacked, and the forming step of the conducting layer comprises: 15 .

Step 1: A water-cooled baffle is arranged between the surface of the adhesive layer corresponding to the second functional section and the evaporation source, and the water-cooled baffle is provided with a plurality of through holes for steam to pass through. The arrangement density of each through hole gradually decreases along the direction from the first functional section to the second functional section, and the surface of the adhesive layer is plated with aluminum by an evaporation method;

Step 3: using the evaporation method of Step 1 to form an aluminum layer on the reinforcement layer obtained in the previous step, to obtain a diversion layer with inconsistent thickness;

16. The method for preparing a positive electrode current collector according to claim 14 or 15, wherein the step of forming the reinforcement layer on the aluminum layer comprises:

The aluminized film whose outermost layer is an aluminum layer is placed in an environment with a humidity of less than 50% for 46-50 hours, so that the reinforcement layer is formed on the aluminum layer;

Or use plasma equipment to ionize argon and oxygen to clean and oxidize the surface of the aluminum layer, so that the reinforcement layer is formed on the aluminum layer.