Positive plate, lithium ion battery and electric device

Abstract

The utility model relates to a positive plate, a lithium ion battery and an electric device. The positive plate comprises a positive current collector, the two ends of the positive current collector in the length direction are a head end and a tail end respectively, after the positive current collector is wound, the head end is located in a roll core, and the tail end is located on the outer ring of the roll core; wherein the tail end is provided with a single-sided area, one side of the single-sided area along the thickness direction is coated with an active material layer, the other side of the single-sided area is an empty foil area, and the surface of a current collector of the empty foil area is coated with a coating. According to the scheme provided by the invention, the positive plate can prevent the edge of the two-fold empty foil area at the tail end from rolling, and can improve the combination effect of the positive plate, the diaphragm and the negative plate, so that the problem of black spots or lithium precipitation at the edge of the two-fold part at the tail end of the positive plate can be avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy, in particular to a positive electrode sheet, a lithium ion battery and an electric device. BACKGROUND

[0002] With the wide application of lithium ion battery products, higher and higher requirements are put forward for the long cycle life of lithium ion batteries in order to improve the product competitiveness. After the cycle of the lithium ion battery, black spot lithium precipitation problems are prone to occur in the edge region of the two-fold single surface material of the outermost circle of the winding core, which affects the life of the battery to some extent. The main reason for the black spot lithium precipitation is that the aluminum foil in the edge region of the two-fold single surface material of the outermost circle of the winding core has weak anti-deformation ability and is prone to edge rolling, thereby causing the positive electrode sheet and the negative electrode sheet in the edge region of the tail two-fold to be in poor contact, the lithium ion migration impedance to be large, the electrolyte to be consumed faster in the battery charge and discharge cycle process, and finally causing black spots or lithium precipitation.

[0003] Therefore, how to solve the edge region rolling of the two-fold single surface material of the outermost circle of the winding core of the lithium ion battery and thereby avoid black spots or lithium precipitation has become a problem to be solved. CONTENT OF THE INVENTION

[0004] To solve or partially solve the problems in the related art, the present application provides a positive electrode sheet, a lithium ion battery and an electric device, which can avoid the edge region of the tail two-fold empty foil area from rolling, can improve the combination effect of the positive electrode sheet and the separator and the negative electrode sheet, and thereby can avoid the edge region of the tail two-fold part of the positive electrode sheet from having black spots or lithium precipitation problems.

[0005] The first aspect of the present application provides a positive electrode sheet, comprising:

[0006] a positive electrode current collector, two ends of the positive electrode current collector along the length direction are a head end and a tail end respectively, after the positive electrode current collector is wound, the head end is located inside the winding core, and the tail end is located at the outer circle of the winding core;

[0007] wherein the tail end is provided with a single surface area, one side of the single surface area along the thickness direction is coated with an active material layer, and the other side is an empty foil area, and the surface of the current collector of the empty foil area is coated with a coating layer.

[0008] In an implementation manner, the thickness of the coating layer is less than the thickness of the active material layer.

[0009] In an implementation manner, the coating layer is coated along the length direction of the current collector; and the end part of the coating layer close to the tail end of the positive electrode current collector is aligned with the end part of the positive electrode active material layer on the other side of the single surface area.

[0010] In an implementation manner, the positive electrode sheet comprises a two-fold area located at the outer circle of the winding core after being wound, the two-fold area is the single surface area, and the empty foil area of the single surface area is coated with the coating layer.

[0011] In an implementation form, the coating has a thickness of 1-120 pm.

[0012] In an implementation form, the coating has a hardness greater than a hardness of the positive current collector.

[0013] In an implementation form, the coating is at least one of a nylon, a polymer coating, a nanocomposite coating, a ceramic coating, or an organic-inorganic hybrid coating.

[0014] In an implementation form, the coating is applied to the entire surface of the empty foil region; or,

[0015] In an implementation form, the coating is applied to the edge portions of the empty foil region along both sides in the width direction of the current collector.

[0016] The second aspect of the application provides a lithium ion battery, comprising:

[0017] A positive electrode sheet, a separator, and a negative electrode sheet, the positive electrode sheet having the features of the positive electrode sheet according to the first aspect described above;

[0018] The positive electrode sheet, the separator, and the negative electrode sheet are wound to form a winding core of the lithium ion battery.

[0019] The third aspect of the application provides an electrical device, comprising:

[0020] A body, the body being provided with the lithium ion battery according to the second aspect described above.

[0021] The technical solution provided by the application can have the following beneficial effects:

[0022] The positive electrode sheet provided by the application has an active material layer on one side of the tail end single-sided region in the thickness direction, and the other side is an empty foil region. The surface of the current collector of the empty foil region is coated with a coating. The coating can enhance the toughness and deformation resistance of the empty foil region at the tail end of the positive electrode sheet, thereby avoiding the occurrence of the rolling phenomenon at the edge of the empty foil region. The combination effect of the positive electrode sheet, the separator, and the negative electrode sheet can be improved, thereby reducing the lithium ion migration impedance. The occurrence of black spot lithium precipitation at the edge of the two folding portions at the tail end of the positive electrode sheet can be avoided. At the same time, the consumption rate of electrolyte during the charge and discharge cycle of the lithium ion battery can be reduced, thereby improving the service life of the lithium ion battery.

[0023] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the application. BRIEF DESCRIPTION OF DRAWINGS

[0024] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description thereof taken in conjunction with the accompanying drawings, in which like reference characters designate the same elements throughout the attached drawings. In the drawings:

[0025] Figure 1 is a side view of a positive electrode sheet according to an embodiment of the present application;

[0026] Figure 2 is a front view of a positive electrode sheet according to an embodiment of the present application;

[0027] Figure 3 is a structural view of a lithium ion battery jelly-roll according to an embodiment of the present application;

[0028] Figure 4 is a cross-sectional view of a lithium ion battery jelly-roll according to an embodiment of the present application; Figure 3

[0029] Figure 5 is a cross-sectional view of a lithium ion battery jelly-roll according to an embodiment of the present application;

[0030] Reference numerals: 100, positive electrode sheet; 110, positive electrode current collector; 120, active material layer; 130, single-sided region; 131, coating layer; 200, jelly-roll; 201, two-fold region; 210, negative electrode sheet; 220, separator. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present application will be described herein below with reference to the accompanying drawings. While the preferred embodiments of the present application are shown in the drawings, it is understood that the present application can be embodied in many different forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0033] ​It should be understood that, although the terms "first", "second", "third", etc. can be used in this application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information without departing from the scope of the present application. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0034] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0035] Unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] In the related art, the aluminum foil in the edge region of the outermost two-fold single-sided material of the lithium ion battery roll core has weak anti-deformation ability, and the edge roll phenomenon is easy to occur, thereby causing the positive plate and the negative plate in the tail two-fold edge part to contact poorly, the lithium ion migration impedance to be large, the electrolyte to be consumed faster in the battery charge and discharge cycle process, and finally causing black spots or lithium precipitation. In view of the above problems, the present application provides a positive plate, which can avoid the occurrence of the roll phenomenon in the edge of the tail two-fold empty foil area, can improve the combination effect of the positive plate, the separator and the negative plate, and thereby can avoid the black spot or lithium precipitation problem in the edge of the tail two-fold part of the positive plate.

[0037] The technical solutions of the embodiments of the present application are described in detail below with reference to the drawings.

[0038] Figure 1 is a side view of the positive plate shown in the embodiments of the present application; Figure 2 is a front view of the positive plate shown in the embodiments of the present application; Figure 3FIG. 1 is a structural schematic diagram of a lithium ion battery roll core according to an embodiment of the present application.

[0039] Referring to Figures 1-3 , the present application provides a positive electrode sheet 100, comprising a positive electrode current collector 110, the two ends of the positive electrode current collector 110 along the length direction are respectively a head end A and a tail end B, after the positive electrode current collector 110 is wound, the head end A is located inside a roll core 200( Figure 3 shown) and the tail end B is located at the outer circle of the roll core 200; wherein, the tail end is provided with a single-sided area 130, one side of the single-sided area 130 along the thickness direction is coated with an active material layer 120, and the other side is a blank foil area, and the current collector surface of the blank foil area is coated with a coating layer 131.

[0040] Referring to Figure 1 and Figure 2 , the thickness direction of the positive electrode sheet is the Z direction of the coordinate axis, the width direction is the Y direction, and the length direction is the X direction.

[0041] The positive electrode sheet 100 provided by the present application, the single-sided area 130 of the tail end of the positive electrode sheet 100 is coated with an active material layer 120 on one side along the thickness direction Z( Figure 1 , the lower side in the figure), the other side along the thickness direction( Figure 1 , the upper side in the figure) is a blank foil area, the length of the blank foil area is L, and the current collector surface of the blank foil area is coated with a coating layer 131.

[0042] Figure 5 FIG. 2 is a sectional view of a lithium ion battery roll core of the related art, referring to Figure 5 , the positive electrode sheet of the lithium ion battery of the related art is prone to winding at C, which makes the combination effect of the positive electrode sheet at C with the separator and the negative electrode sheet poor, resulting in the occurrence of black spots or lithium precipitation at C.

[0043] Referring to Figure 3 and Figure 4 , the coating layer 131 can enhance the toughness and anti-deformation ability of the blank foil area of the tail end of the positive electrode sheet 100, thereby avoiding the occurrence of winding at the edge of the blank foil area, improving the combination effect of the positive electrode sheet 100 with the separator and the negative electrode sheet 210, thereby reducing the lithium ion migration impedance, so as to avoid the occurrence of black spot and lithium precipitation at the edge of the two folding parts of the tail end of the positive electrode sheet 100, and at the same time, the consumption speed of the electrolyte in the charging and discharging cycle process of the lithium ion battery can be reduced, thereby improving the service life of the lithium ion battery.

[0044] The positive electrode current collector 110 of the present application can be an aluminum foil, and the active material layer 120 coated on the surface of the positive electrode current collector 110 is used to store and release lithium ions. The single-sided area 130 refers to an area of the positive electrode tab having the active material layer 120 on one side and no active material layer 120 on the other side, i.e., the empty foil area.

[0045] Referring to Figure 3 , the two-fold of the tail end of the positive electrode tab generally refers to a process in which the tail of the positive electrode tab 100 is bent twice during winding or folding in the lithium battery manufacturing process. The positive electrode tab 100 of the present application is co-wound with the negative electrode tab 210 and the separator film to form a winding core 200.

[0046] In the present application, when the positive electrode tab 100 is in a wound state, the head end A of the positive electrode tab 100 is located inside the winding core 200, and the tail end B is located at the outermost circle of the winding core 200. The single-sided area 130 of the tail end B of the positive electrode tab 100 will be bent twice during winding, thereby forming two-fold areas 201 on both sides of the winding core in the thickness direction. The first bending is to enable the tail of the positive electrode tab 100 to closely fit the outermost circle of the wound battery core, and the second bending is to further increase the contact area and the conductivity stability. The area of the positive electrode tab 100 between the first bending and the second bending is referred to as the two-fold area 201.

[0047] In the present application, the positive electrode tab 100 includes the two-fold area 201 located at the outermost circle of the winding core 200 after winding. The two-fold area 201 is also a single-sided area 130, and the empty foil area of the single-sided area 130 is coated with a coating layer 131. After such arrangement, the coating layer 131 can improve the anti-deformation ability of the current collector of the two-fold area, and the positive electrode tab 100 in the two-fold area at the outermost circle of the winding core 200 will not be rolled, so that the combination of the positive electrode tab 100 in the two-fold area with the separator film and the negative electrode tab 210 is better.

[0048] Continuing to refer to Figure 1 In some embodiments, the coating layer 131 is coated along the length direction X of the current collector, and the end of the coating layer 131 close to the tail end B of the positive electrode current collector 110 is aligned with the end of the positive electrode active material layer 120 on the other side of the single-sided area 130. The predetermined length area on both sides of the end of the tail end B of the positive electrode tab 100 is not coated with the active material layer 120 and the coating layer 131. After the positive electrode tab 100 is wound into a winding core 200, the overall thickness of the winding core 200 can be reduced, thereby improving the energy density of the lithium ion battery.

[0049] In some embodiments, the coating layer 131 is coated on both side edge parts of the empty foil area along the width direction Y of the current collector, i.e., the middle area of the current collector surface of the empty foil area opposite to the other active material layer 120 is not coated with the coating layer 131, and the coating layer 131 is coated on the edges along the width direction Y of the current collector. Referring toFigure 5 Since the edge portions of the current collector along the width direction Y of the current collector are prone to curling inward, the current collector of the empty foil area presents an arc shape, as shown in Figure 4 The embodiment coats the coating layer 131 at the edge portions of the empty foil area prone to curling, thereby improving the deformation resistance of the edge portions of the empty foil area and avoiding curling of the edge portions of the empty foil area.

[0050] In some embodiments, the coating layer 131 is coated on the entire surface of the empty foil area, that is, a layer of the coating layer 131 is uniformly coated on the entire surface of the empty foil area opposite to the other active material layer 120. Since the middle portion and the edge portion of the empty foil area are both coated with the coating layer 131, the deformation resistance of the entire empty foil area is improved, thereby avoiding curling of the edge portion of the empty foil area.

[0051] In some embodiments, the thickness of the coating layer 131 is less than the thickness of the second active material layer 120. After the positive electrode sheet 100 is wound into the jelly-roll 200, the overall thickness of the jelly-roll 200 is further reduced, and the power density of the lithium ion battery is improved.

[0052] In some embodiments, the thickness of the active material layer 120 is about 150 μm, and the thickness of the coating layer 131 is 1 μm-120 μm.

[0053] In some embodiments, the hardness of the coating layer 131 is greater than the hardness of the positive electrode current collector 110. Since the material of the coating layer 131 has high hardness and high mechanical strength, coating the coating layer 131 with high hardness on the surface of the current collector can enhance the overall mechanical strength of the positive electrode sheet 100, thereby avoiding curling of the edge portion of the empty foil area.

[0054] In some embodiments, the material of the coating layer 131 is at least one of nylon, a polymer coating layer 131, a nano-composite coating layer 131, a ceramic coating layer 131, or an organic-inorganic hybrid coating layer 131, but is not limited thereto. In other embodiments, the coating layer 131 can also be other materials having similar properties to the above-mentioned materials.

[0055] In some embodiments, when the coating layer 131 is a nylon coating layer, the nylon material itself has high mechanical strength, which can enhance the overall mechanical strength of the positive electrode sheet 100.

[0056] When the coating 131 is a polymer coating, high molecular materials such as polyester and polyurethane can be used as the coating 131, which can significantly improve the toughness and corrosion resistance of the current collector, so that the positive plate 100 not only has good mechanical strength, but also provides excellent chemical stability. When a nanocomposite coating 131 is used, nanoparticles (such as silicon dioxide, aluminum oxide, etc.) can be added to the coating 131, which can greatly improve the toughness and wear resistance of the coating 131. The nanoparticles can enhance the bonding force between the current collector and the coating 131, and at the same time improve the physical properties of the coating 131.

[0057] When the coating 131 is a ceramic coating, ceramic materials such as aluminum oxide and silicon nitride can be used for coating 131 treatment. Although the hardness is high, the toughness is poor. The present embodiment improves the toughness of the coating 131 by adding organic polymers or using a multi-layer composite structure.

[0058] When the coating 131 is a metal coating, a layer of metal (such as nickel, copper, etc.) is deposited on the surface of the current collector by electroplating or chemical plating, which can improve the toughness and corrosion resistance of the current collector. At the same time, the metal coating also has good electrical conductivity and weldability.

[0059] When the coating 131 is an organic-inorganic hybrid coating, the organic-inorganic hybrid coating is a combination of organic and inorganic materials, so that the coating 131 has the advantages of both organic and inorganic materials. For example, combining silane coupling agent with polymer makes the coating 131 have good mechanical properties and excellent chemical stability.

[0060] The above introduces the positive plate 100 of the present application, accordingly, the present application also provides a lithium ion battery.

[0061] Continuing to refer to Figure 3 and Figure 4 The lithium ion battery package, the positive plate 100, the separator 220 and the negative plate 210, the positive plate 100 has the characteristics of the positive plate 100 of the above embodiment; wherein the positive plate 100, the separator 220 and the negative plate 210 are wound to form a roll core 200 of the lithium ion battery.

[0062] The lithium ion battery provided by the present application, the tail end of the positive plate 100 is provided with a single-sided area 130, one side of the single-sided area 130 along the thickness direction is coated with an active material layer 120, and the other side is a blank foil area, the surface of the current collector of the blank foil area is coated with a coating 131. The coating 131 can enhance the toughness of the current collector of the blank foil area, enhance the deformation resistance of the aluminum foil, and further improve the contact effect of the edge part of the tail end of the positive plate 100 and the negative plate 210, reduce the lithium ion migration impedance, reduce the consumption speed of the electrolyte in the charging and discharging cycle process of the lithium ion battery, and further avoid the problem of black spot lithium precipitation at the edge part of the tail end of the positive plate 100, thereby improving the service life of the lithium ion battery.

[0063] The application also provides a power consuming device comprising a body, wherein the body is installed with the lithium ion battery of any one of the above embodiments. The power consuming device can be a mobile communication device, a sound equipment, a game machine, a smart door lock, etc., but is not limited thereto, and the lithium ion battery of the application provides power supply for the power consuming device.

[0064] The above has described the embodiments of the application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, practical application, or improvement to the technology in the market, or to enable other ordinary skilled in the art to understand the embodiments disclosed herein.

Claims

1. A positive electrode sheet characterized by comprising: Comprising: a positive electrode current collector, two ends of the positive electrode current collector along the length direction are a head end and a tail end respectively, after the positive electrode current collector is wound, the head end is located inside the winding core, and the tail end is located at the outer circle of the winding core; wherein the tail end is provided with a single-sided area, one side of the single-sided area along the thickness direction is coated with an active material layer, and the other side is a hollow foil area, and the current collector surface of the hollow foil area is coated with a coating layer.

2. The positive electrode sheet according to claim 1, characterized in that: the thickness of the coating layer is less than the thickness of the active material layer.

3. The positive electrode sheet according to claim 1, characterized in that: the coating layer is coated along the length direction of the current collector; and the end of the coating layer close to the tail end of the positive electrode current collector is aligned with the end of the positive electrode active material layer on the other side of the single-sided area.

4. The positive electrode sheet according to claim 1, characterized in that: the positive electrode sheet comprises a two-fold area located at the outer circle of the winding core after winding, the two-fold area is the single-sided area, and the hollow foil area of the single-sided area is coated with the coating layer.

5. The positive electrode sheet according to claim 1, characterized in that: the thickness of the coating layer is 1 μm-120 μm.

6. The positive electrode sheet according to claim 1, characterized in that: the hardness of the coating layer is greater than the hardness of the positive electrode current collector.

7. The positive electrode sheet according to claim 1, characterized in that: the material of the coating layer is at least one of nylon, a polymer coating layer, a nano-composite material coating layer, a ceramic coating layer, or an organic-inorganic hybrid coating layer.

8. The positive electrode sheet according to claim 1, characterized in that: the coating layer is coated on the entire surface of the hollow foil area; or the coating layer is coated on the edge parts of both sides of the hollow foil area along the width direction of the current collector.

9. A lithium-ion battery, characterized by Comprising: a positive electrode sheet, a separator, and a negative electrode sheet, the positive electrode sheet has the features of the positive electrode sheet according to any one of claims 1-8; wherein the positive electrode sheet, the separator, and the negative electrode sheet are wound to form a winding core of the lithium ion battery.

10. An electrical device, characterized by Comprising: a body, the body is installed with the lithium ion battery according to claim 9.

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