WO2023236070A9

WO2023236070A9 - Electrochemical device and electric apparatus

Info

Publication number: WO2023236070A9
Application number: PCT/CN2022/097533
Authority: WO
Inventors: 周卫源; 郝海姣
Original assignee: 宁德新能源科技有限公司; 东莞新能安科技有限公司
Priority date: 2022-06-08
Filing date: 2022-06-08
Publication date: 2024-02-01
Also published as: WO2023236070A1; CN115380399A

Abstract

An electrochemical device and an electric apparatus. The electrochemical device comprises an electrode assembly, and the electrode assembly is formed by winding a first plate, a second plate and a separator in a first direction, wherein the first direction refers to a winding direction, and a second direction is perpendicular to the first direction; the first plate comprises a first active material layer, and the second plate comprises a second active material layer; and in the first direction, the difference between the widths of the first active material layer and the second active material layer in the second direction is increased. In the electrochemical device, the distance between an edge of the first active material layer and an edge of the second active material layer increases in the second direction, so that a large movement space can be provided between the first active material layer and the second active material layer, and the distance between the edge of the first active material layer and the edge of the second active material layer can be better controlled during winding, thus reducing the probability of the edge of the first active material layer exceeding the edge of the second active material layer during winding, and improving the volumetric energy density and safety performance of the electrochemical device.

Description

An electrochemical device and electrical equipment

Technical field

The present application relates to the technical field of electrochemical devices, and in particular to an electrochemical device and electrical equipment.

Background technique

Due to their rechargeability and reusability, secondary batteries are widely used in various electrical equipment, such as portable electrical equipment. During the manufacturing process of secondary batteries, the performance of secondary batteries may be affected due to process or equipment reasons.

Contents of the invention

The inventor was surprised to find that during the battery production process, due to equipment accuracy in the winding process and other reasons, the edge spacing of the negative electrode plate and the positive electrode plate active material layer will change, the closer to the end of the electrode plate winding, resulting in The distance between the edge of the positive active material layer and the edge of the negative active layer is getting smaller and smaller, and even the edge of the positive active material layer exceeds the edge of the negative active layer. When the positive active material layer is close to or beyond the edge of the negative active material layer, the safety performance and volumetric energy density of the battery will be affected. For example, during the charging and discharging process of a lithium-ion battery, if the distance between the edge of the positive active material layer and the negative active layer becomes smaller and smaller, the probability of direct contact is greater. Due to the conductivity of the electrolyte, a short circuit may occur, thus affecting the safety of the battery. Performance; Furthermore, ions are deintercalated from the positive active material layer and cannot be embedded in the negative active material layer, so a part of the energy density will be lost, thus affecting the volumetric energy density of the battery.

In order to improve the above technical problems, the purpose of the embodiments of the present application is to provide an electrochemical device and electrical equipment to control the distance between the edge of the active material layer of the negative electrode sheet and the edge of the active material layer of the positive electrode sheet during the winding process, so as to improve the electrochemical performance. Volumetric energy density of chemical devices and product safety performance.

The specific technical solutions are as follows:

An embodiment of the first aspect of the present application provides an electrochemical device, including an electrode assembly. The electrode assembly is composed of a first pole piece, a second pole piece and an isolation film rolled along a first direction. The direction is the winding direction, the second direction is perpendicular to the first direction, the first pole piece includes a first active material layer, the second pole piece includes a second active material layer; along the first direction, the difference in width of the first active material layer and the second active material layer in the second direction increases. The "difference" in this application refers to the absolute value of the difference between two numbers, and the same is true below.

In some embodiments, the first active material layer includes a first part and a second part, the first part is close to the winding starting end of the first pole piece, and the second part is far away from the winding starting end of the first pole piece; the width of the first part is greater than The width of the second part.

In some embodiments, the first active material layer includes a first part and a second part, the first part is far away from the winding starting end of the first pole piece, and the second part is close to the winding starting end of the first pole piece; the width of the first part is greater than The width of the second part.

In some embodiments, the length of the first part along the first direction is 0.5 to 0.8 times the length of the first active material layer. This is because the first part starts winding first and exceeds the length of the second active material layer. The probability of the material layer is very small. While ensuring that the second part after winding does not exceed the edge of the second active material layer, making the first part as long as possible and the second part as short as possible can reduce the risk of the second part. The effect of length on the energy density of the first pole piece and battery assembly.

In some embodiments, the difference between the width of the first part and the width of the second part is 0.1 mm to 5 mm. The movement space of the second part along the second direction Z during the winding process can be increased, the distance between the edge of the outer ring part and the edge of the second active material layer can be further controlled during the winding process, and the edge of the second part beyond the second active material layer can be further reduced. The probability of the edge of the second active material layer is reduced, and the probability of energy density loss of the first pole piece and electrode assembly caused by the width of the second part being too small can be reduced.

In some embodiments, the difference between the width of the first part and the width of the second active material layer is 0.2 mm to 5 mm, and the difference between the width of the second part and the width of the second active material layer is 0.2 mm to 5 mm. The difference is 0.3mm to 5.5mm.

In some embodiments, the first active material layer further includes a transition part, one side of the transition part is connected to the first part, and the other side is connected to the second part; along the line from the first part to the In the direction of the second portion, the width of the transition portion gradually decreases along a second direction perpendicular to the first direction. The transition part is used to achieve a width transition between the first part and the second part, so that the width of the first active material layer transitions from the first part to the second part more smoothly, thereby improving the safety performance of the first pole piece and the electrode assembly. .

In some embodiments, the transition portion includes a first side and a second side, and the first side and/or the second side are arc-shaped. This makes the width of the transition part change more smoothly from the side close to the first part to the side close to the second part, so that the width of the first active material layer can transition from the first part to the second part more smoothly.

In some embodiments, the length of the transition portion along the first direction is 1 mm to 10 mm. The space occupied by the transition part on the first active material layer can be reduced, and the influence of the transition part on the number of turns of the outer ring part formed after the second part is wound can be reduced.

In some embodiments, the first portion includes a third side and a fourth side along the second direction, and the second portion includes a fifth side and a sixth side. The third side and the fifth side are located on the same straight line, and the fourth side and the sixth side are not located on the same straight line. This further reduces the probability that the first active material layer exceeds the edge of the second active material layer during the winding process, and can increase the overall area of the first active material layer, thereby increasing the capacity and energy density of the electrochemical device.

In some embodiments, the third side and the fifth side are not located on the same straight line, and the fourth side and the sixth side are not located on the same straight line. It can be added that the first part and the third side are not located on the same straight line. The width difference between the two parts further reduces the probability that the first active material layer exceeds the second active material layer, further improving the volumetric energy density of the electrochemical device and the safety performance of the product.

In some embodiments, along the first direction, the first part includes a first section and a second section, and the first section is closer to the winding start end than the second section, The length of the first section along the first direction is 0.14 to 0.5 times the length of the first portion, and the width of the first section is smaller than the width of the second section. Reduce the probability that the first section will exceed the second active material layer due to the displacement in the second direction when the winding needle is pulled out after the winding is completed, thereby further improving the volumetric energy density and energy density of the electrochemical device. product safety performance.

In some embodiments, along the first direction, the second part includes a third section and a fourth section, and the fourth section is farther away from the rolled-up part than the third section. At the beginning, the length of the third section along the first direction is 0.5 to 0.75 times the length of the second section, and the width of the third section is greater than the width of the fourth section . The distance between the edge of the third region and the edge of the fourth section and the edge of the second active material layer can be better controlled, reducing the probability that the third section and the fourth section exceed the second active material layer, and increasing The overall area of the first active material layer increases the capacity and energy density of the electrochemical device.

In some embodiments, the electrode assembly further includes a conductive portion connected to the second area of the first pole piece that is not coated with the first active material layer.

In some embodiments, the electrochemical device further includes a housing, and the electrode assembly is placed in the housing. The shell is used to accommodate the protective electrode assembly and reduce the impact of the external environment on the electrode assembly.

An embodiment of the second aspect of the present application provides an electrical device. The electrical device includes any one of the above electrochemical devices, and the electrochemical device is used to provide electrical energy to the electrical device.

Beneficial effects of the embodiments of this application:

In the electrochemical device provided by the embodiment of the present application, the electrode assembly of the electrochemical device is formed by winding the first pole piece, the second pole piece and the separator layer. The first direction is the winding direction, and the second direction is perpendicular to the In one direction, the first pole piece includes a first active material layer, and the second pole piece includes a second active material layer; along the first direction, the difference in width of the first active material layer and the second active material layer in the second direction increase. Therefore, during the winding process of the first pole piece and the second pole piece, the distance between the edge of the first active material layer and the edge of the second active material layer can be better controlled, and the edge of the first active material layer can be reduced. The probability of exceeding the edge of the second active material layer improves the volumetric energy density of the electrochemical device and the safety performance of the product.

Description of drawings

In order to explain the embodiments of the present invention and the technical solutions of the prior art more clearly, the drawings needed to be used in the embodiments and the prior art are briefly introduced below. Obviously, the drawings in the following description are only for the purpose of explaining the embodiments of the present invention and the technical solutions of the prior art. For some embodiments of the invention, those of ordinary skill in the art can also obtain other embodiments based on these drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of an electrode assembly in some embodiments of the present application;

Figure 2 is a schematic structural diagram of a first pole piece and a second pole piece in some embodiments of the present application;

Figure 3 is a schematic structural diagram of a first pole piece in some embodiments of the present application;

Figure 4 is a view along the second direction of a first pole piece in some embodiments of the present application;

Figure 5 is a view along the second direction of a second pole piece in some embodiments of the present application.

Figure 6 is a schematic structural diagram of a first pole piece with a transition part in some embodiments of the present application;

Figure 7 is another structural schematic diagram of a first pole piece with a transition part in some embodiments of the present application;

Figure 8 is another structural schematic diagram of a first pole piece with a transition portion in some embodiments of the present application;

Figure 9 is another structural schematic diagram of a first pole piece in some embodiments of the present application;

Figure 10 is another structural schematic diagram of a first pole piece in some embodiments of the present application;

Figure 11 is a schematic structural diagram of another first pole piece with a transition part in some embodiments of the present application;

Figure 12 is another structural schematic diagram of another first pole piece with a transition part in some embodiments of the present application;

Figure 13 is a schematic structural diagram of another first pole piece in some embodiments of the present application;

Figure 14 is another structural schematic diagram of another first pole piece in some embodiments of the present application;

Figure 15 is another structural schematic diagram of a first pole piece and a second pole piece in some embodiments of the present application;

Figure 16 is a schematic structural diagram of an electrochemical device in some embodiments of the present application.

Detailed ways

In order to make the purpose, technical solution, and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

In order to make the purpose, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

The technical solutions in the embodiments of the present application are described clearly and in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the description of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

Hereinafter, embodiments of the present application will be described in detail. This application may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and detailed to those skilled in the art.

Additionally, the size or thickness of various components, layers, or thicknesses in the drawings may be exaggerated for simplicity and clarity. Throughout the text, the same numerical values refer to the same elements. As used herein, the terms "and/or" and "and/or" include any and all combinations of one or more of the associated listed items. Additionally, it will be understood that when element A is referred to as being "connected to" element B, element A may be directly connected to element B, or intervening element C may be present and element A and element B may be indirectly connected to each other.

Further, the use of "may" when describing embodiments of the present application means "one or more embodiments of the present application."

The terminology used herein is for the purpose of describing specific embodiments and is not intended to limit the application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It should be further understood that the term "comprising", when used in this specification, means the presence of the recited features, values, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other features, values , steps, operations, elements, components and/or combinations thereof.

Spatially relative terms, such as "on," etc., may be used herein for convenience to describe the relationship of one element or feature to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device or device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the diagram is turned over, features described as "above" or "on" other features or features would then be oriented "below" or "beneath" the other features or features. Thus, the exemplary term "upper" may include both upper and lower directions. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections do not shall be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the exemplary embodiments.

Some embodiments of the present application are described in detail below. The following embodiments and features in the embodiments may be combined with each other without conflict.

The electrochemical device and electrical equipment provided in the embodiments of the present application will be described in detail below with reference to the accompanying drawings. Among them, the electrochemical device can be a secondary battery such as a lithium-ion battery, a sodium-ion battery, or a polymer battery.

In the embodiment of the present application, the first direction is the winding direction of the first pole piece 11, and the first direction is the direction in which the winding starting end 113 and the winding ending end 114 are arranged oppositely. As shown in Figure 2, the first pole The sheet 11 is generally rectangular. The second direction is perpendicular to the first direction, and the second direction is the width direction of the first pole piece 11 . The third direction is perpendicular to the first direction and the second direction, and the third direction is the thickness direction of the first pole piece 11 . In the embodiment of the present application, the first direction is defined as the X direction, the second direction is the Z direction, and the third direction is the Y direction. The width in the embodiment of this application refers to the length of the area to be measured in the second direction Z.

As shown in Figures 1 to 5, the first embodiment of the present application provides an electrochemical device. The electrochemical device includes an electrode assembly 1. The electrode assembly 1 consists of a first pole piece 11, a second pole piece 12 and an isolation device. The film 13 is wound along the first direction. Among them, the first pole piece 11 includes a first active material layer 1150. The first active material layer 1150 includes a first part 111 and a second part 112. The first part 111 is close to the winding starting end 113 of the first pole piece 11, and the second part 112 is away from the winding ending end 114 of the first pole piece 11 , and the width W1 of the first part 111 is greater than the width W2 of the second part. The width of the first part width W1 refers to, along the first direction, the length of the midpoint of the first part 111 in the second direction, and the same is true for the width of the second part.

In the embodiment of the present application, the first pole piece 11 can be a negative pole piece or a positive pole piece, and the second pole piece 12 can also be a negative pole piece or a positive pole piece, and the first pole piece 11 and the second pole piece 12 Opposite polarity.

When the first pole piece 11 is a negative pole piece and the second pole piece 12 is a positive pole piece, the first active material layer 1150 on the first pole piece 11 is larger than the second active material layer 1210 on the second pole piece 12 . The layer width, that is, in the third direction Y, as long as the first active material layer 1150 covers the second active material layer 1210, along the winding direction, the width of the first active material layer 1150 and the second active material layer 1210 The difference increases. (not shown)

When the first pole piece 11 is a negative pole piece, the first active material layer includes a first part and a second part. The first part is far away from the winding starting end of the first pole piece, and the second part is close to the winding end of the first pole piece. Start; the width of the first part is greater than the width of the second part. (not shown)

As shown in FIG. 4 , the first pole piece 11 may include a first current collector 115 , and the first current collector 115 includes a first region 1151 coated with a first active material layer 1150 and a second region not coated with an active material layer. Area 1152. Further, as shown in FIG. 5 , the second pole piece 12 may include a second current collector 121 , and the second current collector 121 may include a third region 1211 coated with the second active material layer 1210 , and a third region 1211 not coated with the second active material layer 1210 . The fourth region 1212 of the two active material layers 1210.

Taking the first pole piece 11 as a positive pole piece and the second pole piece 12 as a negative pole piece as an example, the material of the first current collector 115 can be aluminum, and the material of the first active material layer 1150 includes a compound that can extract ions, such as Lithium transition metal oxide or sodium transition metal oxide, etc. The material of the second current collector 121 may be copper, and the material of the second active material layer 1210 may include substances that can embed ions, such as carbon materials, silicon materials, etc.

In some embodiments, as shown in FIG. 4 , the first current collector 115 includes a first surface 1154 and a second surface 1155 along the third direction Y. The first active material layer 1150 is located on the first surface 1154 and the second surface 1155 . Optionally, the first active material layer 1150 can be coated on the first side 1154 by continuous coating. Optionally, after the first active material layer 1150 is coated on the first side 1154, the first active material layer 1150 can be coated on the second side 1155 by gap coating.

In some embodiments, as shown in FIG. 5 , the second current collector 121 includes a third surface 1214 and a fourth surface 1215 along the third direction Y. The second active material layer 1210 is located on the third surface 1214 and the fourth surface 1215 . Optionally, the second active material layer 1210 can be coated on the third surface 1214 by continuous coating. Optionally, after the second active material layer 1210 is coated on the third surface 1214, the second active material layer 1210 can be coated on the fourth surface 1215 by gap coating. Optionally, the coating method of the first active material layer 1150 and the second active material layer 1210 includes but is not limited to extrusion coating, transfer coating or gravure printing coating.

In the embodiment of the present application, the isolation film 13 can be a porous plastic film. The isolation film 13 is used to isolate the first pole piece 11 and the second pole piece 12 to prevent the first pole piece 11 and the second pole piece 12 from internal Short circuit, the isolation film 13 is also used to allow electrolytic ions to pass freely to form a conductive path. The materials of the isolation film 12 include polypropylene (PP), polyethylene (PE), copolymers of propylene and ethylene, polyethylene homopolymers, etc.

In the electrochemical device provided by the embodiment of the present application, since the first part 111 is close to the winding starting end 113 of the first pole piece 11 , the second part 112 is far away from the winding starting end 113 of the first pole piece 11 , that is, the second part 112 is close to the winding ending end 114 of the first pole piece 11. After the first pole piece 11 is wound along the first direction X, the first part 111 is located inside the second part 112. The width W1 of the first part 111 is greater than the width W2 of the second part 112 . Therefore, the width difference between the first part 111 and the second active material layer 1210 in the second pole piece 12 is smaller than the width difference between the second part 112 and the second active material layer 1210 in the second pole piece 12 . The width of the active material layer 1210 is different. During the winding process of the first pole piece 11 and the second pole piece 12 , compared with the first part 111 , there is a larger width difference between the second part 112 and the second active material layer 1210 , and the second part 112 It is far away from the winding starting end 113 of the first pole piece 11 , so during the winding process of the first pole piece 11 and the second pole piece 12 , the edge of the second part 112 and the second active material layer 1210 can be better controlled. The edge spacing can better control the spacing between the edge of the first active material layer 1150 and the edge of the second active material layer 1210, and reduce the probability that the edge of the first active material layer 1150 exceeds the edge of the second active material layer 1210, Improve the volumetric energy density of electrochemical devices and the safety performance of products.

In some embodiments, as shown in FIG. 3 , the length L1 of the first portion 111 along the first direction X is 0.5 to 0.8 times the length L2 of the first active material layer 1150 . This is because the first part 111 starts to be wound first, and the probability of it exceeding the second active material layer 1210 is very small. When ensuring that the second part 112 does not exceed the edge of the second active material layer 1210 after being rolled as much as possible, Making the first part 111 as long as possible and the second part 112 as short as possible can reduce the impact of the length of the second part 112 on the energy density of the first pole piece 11 and the battery assembly.

In the embodiment of the present application, the length L1 of the first part 111 is 0.5 to 0.8 times the length L2 of the first active material layer 1150, so that after the first pole piece 11 is wound, the inner ring portion formed by the first part 11 The number is 0.5 to 0.8 times the total number of winding turns of the first active material layer 1150 . For example, assuming that the number of winding turns of the entire first active material layer 1150 is 20 turns, the number of turns formed by winding the first part 11 may be 10 to 16 turns.

In some embodiments, the difference between the width W1 of the first part 111 and the width W2 of the second part 112 is 0.1 mm to 5 mm. During the winding process of the first pole piece 11, compared with the first part 111, the movement range of the second part 112 in the second direction Z is 0.1 mm to 5 mm longer. The difference between the width W1 of the first part 111 and the width W2 of the second part 112 is greater than or equal to 0.1 mm, which can increase the movement space of the second part 112 along the second direction Z during the winding process, and can further control the outer ring during the winding process. The distance between the edge of the portion and the edge of the second active material layer 1210 further reduces the probability that the edge of the second portion 112 exceeds the edge of the second active material layer 1210 . The difference between the width W1 of the first part 112 and the width W2 of the second part 112 is less than or equal to 5 mm, which reduces the probability of energy density loss of the first pole piece 11 and the electrode assembly 1 due to the too small width of the second part 112. Optionally, the difference between the width W1 of the first part 111 and the width W2 of the second part 112 is 0.3 mm.

Specifically, the above embodiments will be further described below in conjunction with examples and comparative examples. As shown in Table 1, Table 1 shows the energy density value of the battery after the battery is fully charged.

Table 1

As shown in Table 1, the first pole piece in Table 1 can be a negative pole piece, and the second pole piece can be a positive pole piece. In the comparative example, the first part and the second part of the first active material layer in the first pole piece have the same width. In the embodiment, the width of the first part of the first active material layer in the first pole piece is greater than the width of the second part, and the width difference between the first part and the second part is 0.5 mm. By comparing the comparative examples with the embodiments, it can be seen that the dimensions of the batteries are approximately the same. The materials and current collector types of the middle active material layers of the first pole piece and the second pole piece in the comparative examples are the same as those in the embodiments. The width of the first part is larger than When the width of the second part is increased, the cell capacity of the battery increases and the energy density increases. Therefore, making the width of the first part of the first pole piece larger than the width of the second part can improve the volumetric energy density of the electrochemical device and the safety performance of the product.

In some embodiments, as shown in Figures 6, 7, and 8, the first active material layer 1150 also includes a transition portion 116. One side of the transition portion 116 is connected to the first portion 111, and the other side is connected to the second portion 112. . Along the direction from the first part 111 to the second part 112, the width of the transition part 116 in the second direction Z gradually decreases.

In the embodiment of the present application, as shown in FIG. 7 , the transition part 116 is located between the first part 111 and the second part 112 along the first direction X. The width of the side where the transition part 116 is connected to the first part 111 is the largest, and may be equal to the width of the first part 111 . The width of the side where the transition part 116 is connected to the second part 112 is the smallest, and may be equal to the width of the second part 112 . equal. The width of the first part 111 is greater than the width of the second part 112, and the transition part 116 is used to realize a width transition between the first part 111 and the second part 112, so that the width of the first active material layer 1150 transitions from the first part 111 more smoothly. In the second part, the safety performance of the first pole piece 11 and the electrode assembly 1 is improved.

In some embodiments, along the second direction Z, the transition portion 116 includes a first side 1161 and a second side 1162 . The first side 1161 or the second side 1162 is arc-shaped, as shown in FIG. 7 , or both the first side 1161 and the second side 1162 are arc-shaped, as shown in FIG. 8 .

In the embodiment of the present application, as shown in FIGS. 7 and 8 , the first side 1161 or the second side 1162 of the transition part 116 may be arc-shaped, so that the transition part 116 changes from the side close to the first part 111 to the side close to the second part 116 . The width change on one side of the two parts 112 is more gradual, so that the width of the first active material layer 1151 can transition from the first part 111 to the second part 112 more smoothly. The shape of the first side 1161 and the shape of the second side 1162 may be the same or different. Optionally, the first side 1161 is in an arc shape, and the second side 1162 is in an inclined straight line; optionally, the first side 1161 is in an inclined straight line, and the second side 1162 is in an arc shape; optional , both the first side 1161 and the second side 1162 are arc-shaped.

Optionally, as shown in FIG. 6 , the first side 1161 and the second side 1162 are both inclined straight lines. The inclination angles of the first side 1161 and the second side 1162 may be equal or unequal, and this application does not limit this.

In some embodiments, the length of the transition portion 116 along the first direction X is 1 mm to 10 mm. The length of the transition part 116 along the first direction X is also the distance between the first part 111 and the second part 112 along the first direction X. The length of the transition part 116 along the first direction Smoothness of the transition to the width of the second portion 112 . The length of the transition part 116 along the first direction number influence. The length of the transition part 116 can be set according to the width difference between the first part 111 and the second part 112, which is not limited in this application.

In some embodiments, as shown in FIGS. 9 and 10 , along the second direction Z, the first portion 111 includes a third side 1113 and a fourth side 1114 . Along the second direction Z, the second portion 112 includes a fifth side 1123 and a sixth side 1124. The third side 1113 may be located on the same straight line as the fifth side 1123, and the fourth side 1114 may not be located on the same straight line as the sixth side 1124. Or as shown in Figure 9, the third side 1113 may not be located on the same straight line as the fifth side 1123, and the fourth side 1114 may be located on the same straight line as the sixth side 1124, so that the first part 111 can be The width W1 is greater than the width W2 of the second part 112, which further reduces the probability that the first active current collector 1150 exceeds the edge of the second active material layer 1210 during the winding process, and can increase the area of the second part 111, thereby increasing the number of first active materials. The overall area of layer 1150 is increased, thereby increasing the capacity and energy density of the electrochemical device.

Optionally, as shown in Figure 11, the first pole piece 11 includes a transition portion 116. The first side 1161 of the transition portion 116 is not located on the same straight line as the third side 1113 and the fifth side 1123, and the second The side 1162 is located on the same straight line as the fourth side 1114 and the sixth side 1124 . Optionally, as shown in Figure 12, the first side 1161 of the transition portion 116 is located on the same straight line as the third side 1113 and the fifth side 1123, and the second side 1162 is located on the same straight line as the fourth side 1114 and the fifth side 1123. The six sides 1124 are not located on the same straight line.

In some embodiments, the third side 1113 and the fifth side 1123 may not be located on the same straight line, and the fourth side 1114 and the sixth side 1124 may not be located on the same straight line, which can increase the distance between the first part 111 and the second part. The width difference between the parts 112 further reduces the probability that the first active material layer 1150 exceeds the edge of the second active material layer 1210, further improving the volumetric energy density of the electrochemical device and the safety performance of the product.

In some embodiments, as shown in Figure 13, along the first direction At the starting end 113, the length L3 of the first section 1111 along the first direction .

In the embodiment of the present application, the first section 1111 is closer to the winding starting end 113. After the first pole piece 11 is wound, the second section 1112 is located outside the first section 1111 and on the side of the first pole piece 11. During the winding process, the winding needle is located at the first section 1111. The width W5 of the first section 1111 is smaller than the width W6 of the second section 1112, so that the width difference between the first section 1111 and the second active material layer 1210 is larger than that between the second section 1112 and the second active material layer 1210. The width difference between the first section 1111 and the second section 1112 allows the first section 1111 to have a larger displacement space along the second direction Z during the winding process, which can reduce the time required for the winding needle to be withdrawn after the winding is completed. This causes the first section 1111 to be displaced in the second direction Z, resulting in a probability that the first section 1111 exceeds the edge of the second active material layer 1210, thereby further improving the volumetric energy density of the electrochemical device and the safety performance of the product.

In some embodiments, as shown in FIG. 13 , along the first direction Around the starting end 113 , the length L4 of the third section 1121 along the first direction Width W8.

In the embodiment of the present application, the fourth section 1122 is further away from the winding start end 113, the winding end end 114 is closer to the fourth section 1122, and the third section 1121 is closer to the first part 11 than the fourth section 1122. . The width W7 of the third section 1121 is greater than the width W8 of the fourth section 1122, and the third section 1121 can achieve a width transition between the first part 11 and the fourth section 1122. In addition, after the first pole piece 11 is wound, the fourth section 1122 is located outside the third section 1121. During the winding process, the displacement of the fourth section 1122 in the second direction Z may be greater than that of the third section. The displacement of the section 1121 along the Z direction makes the width W7 of the third section 1121 larger than the width W8 of the fourth section 1122, so that the edge of the third section 1211 and the edge of the fourth section 1122 and the second section can be better controlled. The distance between the edges of the active material layer 1210 reduces the probability that the third section 1121 and the fourth section 1122 exceed the edge of the second active material layer 1210, and increases the area of the second part 112, thereby increasing the first active material The overall area of layer 1150 is increased, thereby increasing the capacity and energy density of the electrochemical device.

In some embodiments, the electrode assembly 1 further includes a conductive part 4 connected to the second region 1152 of the first pole piece 11 that is not coated with the first active material layer 1150 .

In the embodiment of the present application, as shown in FIGS. 1 , 4 and 5 , one end of the conductive part 4 is connected to the second region 1152 , and the other end extends out of the second region 1152 along the second direction Z. The conductive part 4 is a conductive component connected to the first pole piece 11 and the second pole piece 12 to draw out current from the first pole piece 11 and the second pole piece 12 . The conductive part 4 may include a first pole tab 41 connected to the first pole piece 11 and a second pole tab 42 connected to the second pole piece 12 . The first tab 41 can be a negative tab or a positive tab, the second tab can be a negative tab or a positive tab, and the first tab 41 and the second tab 42 have opposite polarities.

Taking the first tab 41 as a positive tab and the second tab 42 as a negative tab as an example, the material of the first tab 41 may include at least one of aluminum (Al) or aluminum alloy, and the second tab 42 The material may include at least one of nickel (Ni), copper (Cu) or copper plated with nickel (Ni-Cu). The first tab 41 and the second region 1152 in the first pole piece 11 may be connected by welding or other methods.

In some embodiments, as shown in FIG. 14 , the first region 1151 includes at least one first sub-region 1153 that is not coated with the first active material layer 1150 , and the first tab 41 is connected to the first sub-region 1153 . The third region 1211 of the second pole piece 12 includes at least one third sub-region 1213 that is not coated with the second active material layer 1210 , and the second tab 42 is connected to the third sub-region 1213 .

Optionally, as shown in Figure 14, the first region 1151 includes a plurality of first sub-regions 1153, the conductive part 4 includes a plurality of first tabs 41, and each first tab 41 is connected to a first sub-region 1153. , after the first pole piece 11 is wound, the positions of the plurality of first pole tabs 41 are relative to each other along the third direction X, and the plurality of first pole tabs 41 can be connected to each other.

Optionally, as shown in Figure 15, the third region 1211 includes a plurality of third sub-regions 1213, the conductive part 4 includes a plurality of second tabs 42, and each second tab 42 is connected to a third sub-region 1213. , after the second pole piece 12 is wound, along the third direction X, the positions of the plurality of second pole tabs 42 are opposite, and the plurality of second pole tabs 42 can be connected to each other.

In some embodiments, as shown in FIG. 16 , the electrochemical device further includes a housing 10 , and the electrode assembly 1 is placed in the housing 10 . The housing 10 is used to accommodate the protective electrode assembly 1 and reduce the impact of the external environment on the electrode assembly 1 .

An embodiment of the second aspect of the present application also provides an electrical device. The electrical device includes the electrochemical device in any of the above embodiments, and the electrochemical device is used to provide electrical energy to the electrical device.

Electrical equipment provided by the embodiments of this application include but are not limited to drones, electric vehicles, mobile phones, laptops, electric toys, electric tools, battery cars, and the like. In the electrochemical device included in the electrical equipment provided by the embodiment of the present application, the first part 111 of the first active material layer 1150 is close to the winding starting end 113 of the first pole piece 11 , and the second part 112 of the first active material layer 1150 Far away from the winding starting end 113 of the first pole piece 11 , that is, the second part 112 is close to the winding ending end 114 of the first pole piece 11 . After the first pole piece 11 is wound along the first direction X, the first part 111 is located at the The inner side of the second part 112. The width W1 of the first part 111 is greater than the width W2 of the second part 112 . Therefore, the width difference between the first part 111 and the second active material layer 1210 in the second pole piece 12 is smaller than the width difference between the second part 112 and the second active material layer 1210 in the second pole piece 12 . The width of the active material layer 1210 is different. During the winding process of the first pole piece 11 and the second pole piece 12 , compared with the first part 111 , there is a larger width difference between the second part 112 and the second active material layer 1210 , and the second part 112 It is far away from the winding starting end 113 of the first pole piece 11 , so during the winding process of the first pole piece 11 and the second pole piece 12 , the edge of the second part 112 and the second active material layer 1210 can be better controlled. The edge spacing can better control the spacing between the edge of the first active material layer 1150 and the edge of the second active material layer 1210, and reduce the probability that the edge of the first active material layer 1150 exceeds the edge of the second active material layer 1210, Improve the volumetric energy density of electrochemical devices and the safety performance of products.

The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection of the present application. within the range.

Claims

An electrochemical device includes an electrode assembly. The electrode assembly is formed by winding a first pole piece, a second pole piece and an isolation film in a first direction. The first direction is the winding direction, and the second direction is vertical. In the first direction, where,

The first pole piece includes a first active material layer, and the second pole piece includes a second active material layer; along the first direction, the first active material layer and the second active material layer are at The difference in width in the second direction increases.
The electrochemical device according to claim 1, the first active material layer includes a first part and a second part, the first part is close to the winding starting end of the first pole piece, and the second part is away from the winding start end of the first pole piece. The winding starting end of the first pole piece; the width of the first part is greater than the width of the second part.
The electrochemical device according to claim 1, the first active material layer includes a first part and a second part, the first part is away from the winding starting end of the first pole piece, and the second part is close to the winding start end of the first pole piece. The winding starting end of the first pole piece; the width of the first part is greater than the width of the second part.
The electrochemical device according to claim 2 or 3, wherein the length of the first portion along the first direction is 0.5 to 0.8 times the length of the first active material layer.
The electrochemical device according to claim 2, wherein the difference between the width of the first part and the width of the second part is 0.1 mm to 5 mm.
The electrochemical device according to claim 2, wherein the difference between the width of the first part and the width of the second active material layer is 0.2 mm to 5 mm, and the difference between the width of the second part and the width of the second active material layer is 0.2 mm to 5 mm. The difference between the widths of the active material layers is 0.3 mm to 5.5 mm.
The electrochemical device according to claim 2, wherein the first active material layer further includes a transition part, one side of the transition part is connected to the first part, and the other side is connected to the second part; Along the direction from the first part to the second part, the width of the transition part gradually decreases in a second direction perpendicular to the first direction.
The electrochemical device according to claim 7, wherein along the second direction, the transition portion includes a first side and a second side, the first side and/or the second side The sides are curved.
The electrochemical device of claim 8, wherein the length of the transition portion along the first direction is 1 mm to 10 mm.
The electrochemical device of claim 2 , wherein along the first direction, the first portion includes a first section and a second section, the first section being smaller than the second section Closer to the winding start end, the length of the first section along the first direction is 0.14 to 0.5 times the length of the first part, and the width of the first section is smaller than the The width of the second section.
The electrochemical device according to claim 2, wherein along the first direction, the second part includes a third section and a fourth section, the fourth section being smaller than the third section. The section is further away from the winding start end, the length of the third section along the first direction is 0.5 times to 0.75 times the length of the second part, and the width of the third section greater than the width of the fourth section.
An electrical equipment, wherein the electrical equipment includes the electrochemical device according to any one of claims 1 to 11, and the electrochemical device is used to provide electrical energy to the electrical equipment.