WO2023168954A1

WO2023168954A1 - Battery cell, manufacturing method for battery cell, battery unit, battery, and electric device

Info

Publication number: WO2023168954A1
Application number: PCT/CN2022/128446
Authority: WO
Inventors: 谢超; 王艺若; 林纲
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2022-03-11
Filing date: 2022-10-28
Publication date: 2023-09-14
Also published as: CN116779944A

Abstract

Embodiments of the present application provide a battery cell, a manufacturing method for a battery cell, a battery unit, a battery, and an electric device. The battery cell comprises a first electrode sheet, a second electrode sheet, and a separator located between the first electrode sheet and the second electrode sheet. The first electrode sheet, the second electrode sheet and the separator are wound from a winding starting end along a winding direction to form the battery cell. The battery cell comprises a straight area, and bending areas located at two ends of the straight area. The first electrode sheet is continuous in the winding direction, and the second electrode sheet comprises a first section and a second section which are sequentially arranged along the winding direction, wherein the first section and the second section are disconnected in the bending areas, the second section is continuous in the winding direction, the first section is composed of at least one sheet body, and the sheet body is located in the straight area. According to the battery cell in the embodiments of the present application, in a process of pressing a winding body into a flat structure, there is no problem at a clearance part that a gap between the first electrode sheet and the second electrode sheet is too large, such that the problem of lithium precipitation is avoided, and the problem of the reduction of battery cell performance caused by lithium precipitation can be solved.

Description

Cells, cell manufacturing methods, battery cells, batteries and electrical equipment

cross reference

This application cites Chinese patent application No. 202210239360.1 titled "Battery cells, manufacturing methods of battery cells, battery cells, batteries and electrical equipment" submitted on March 11, 2022, which is fully incorporated by reference into this document. Apply.

Technical field

This application relates to the field of battery technology, and in particular to battery cells, battery cell manufacturing methods, battery cells, batteries and electrical equipment.

Background technique

This section provides merely background information relevant to the present application and is not necessarily prior art.

With the development and progress of battery technology, lithium-ion batteries have been widely used in various electronic devices due to their advantages such as high energy density and low environmental pollution. In some cases, when the wound battery core is processed and formed, there is a gap between the positive electrode piece and the negative electrode piece after winding. When the gap is large, it is easy to cause the problem of lithium precipitation, resulting in a decrease in the performance of the battery cell. It may even cause safety issues such as short circuits. Therefore, how to improve the performance and safety performance of battery cells is a problem that needs to be solved.

Contents of the invention

The purpose of this application is to provide a battery cell, a battery cell manufacturing method, a battery cell, a battery and electrical equipment, so as to improve the battery cell performance. In order to achieve the above purpose, this application provides the following technical solutions:

An embodiment of the first aspect of the present application provides an electric core. The battery core includes: a first pole piece, a second pole piece, and an isolation film located between the first pole piece and the second pole piece. The three are wound along the winding direction to form the battery core; the battery core includes a flat area and an isolation film located between the first pole piece and the second pole piece. In the bending areas at both ends of the straight area, the first pole piece is continuous in the winding direction, and the second pole piece includes a first section and a second section arranged sequentially along the winding direction, wherein the first section and the second section It is broken in the bending area, and the second section is continuous in the winding direction. The first section is composed of at least one sheet body, and the sheet body is located in the straight area.

According to the battery core in the embodiment of the present application, the wound battery core includes a straight area and a bent area, and the first section and the second section of the second pole piece are disconnected in the bent area of the battery core to form a third One section of the sheet body is arranged in the straight area of the battery core. Therefore, in the bending area of the battery core, the position where the first section and the second section are disconnected form an avoidance area. In this avoidance area, there is no The second pole piece is provided corresponding to the first pole piece. Therefore, lithium ions will not be deintercalated in the avoidance area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of a large gap between the first pole piece and the second pole piece in the avoidance area, so that the problem of lithium precipitation will not occur. , which can then solve the problem of battery cell performance degradation caused by lithium precipitation.

In some embodiments of the present application, the first section includes a plurality of sheet bodies, and each sheet body is spaced apart along the winding direction and is located in a straight area. Multiple sheets can form multiple avoidance portions located in the bending area, thereby improving the lithium deposition problem in the bending area of the inner ring.

In some embodiments of the present application, multiple sheets are arranged in parallel in the thickness direction of the battery core. In this way, the plurality of sheet bodies and part of the first pole piece can well fill the space near the center of the battery core, making the internal space of the battery core more compact and further increasing the capacity of the battery core.

In some embodiments of the present application, the projections of each sheet in the thickness direction of the battery core are arranged opposite to each other. In this way, compared with staggering the sheets, it is more conducive to allowing each sheet to occupy as large an area as possible in the flat area of the battery core, thereby increasing the area of the active material layer in the battery core. This increases the energy density of the cell per unit area.

In some embodiments of the present application, along the winding direction, from the starting end of the winding, the first pole piece includes a first straight area, a first bending area and a second straight area in order, and the sheet body includes the first sheet body , in the thickness direction of the battery core, the first sheet body is arranged correspondingly to the first straight area, and the first sheet body is located on the side of the first straight area away from the second straight area, and the projection of the first sheet body is completely Located within the projection of the first straight area. In this way, during the process of pressing the winding body into a flat structure, there is no problem of a large gap between the first pole piece and the second pole piece at this location, so that the problem of lithium deposition will not be caused. This can then solve the problem of battery cell performance degradation caused by lithium precipitation.

In some embodiments of the present application, the sheet body further includes a second sheet body. In the thickness direction, the second sheet body is arranged corresponding to the first straight area, and the second sheet body is located between the first straight area and the second straight area. between straight areas. In this way, the second sheet body can utilize the active material at the center of the battery core, making the internal space of the battery core more compact, further increasing the capacity of the battery core, and reducing the waste of active material on the first pole piece.

In some embodiments of the present application, the sheet body further includes a third sheet body. In the thickness direction of the battery core, the third sheet body is arranged corresponding to the second straight area, and the third sheet body is located in the second straight area. The side away from the first straight area. In this way, there is no second pole piece at the corresponding position of the first bending area, which can avoid the occurrence of gaps in the corner areas corresponding to the first bending area, which may cause the problem of lithium deposition in the battery.

In some embodiments of the present application, the first section is wrapped around at most three times in the winding direction. In the related art, the corner of the innermost ring of the battery core is the most serious part of the lithium deposition problem. In this embodiment, when the wound battery core is compressed and shaped, the center part of the battery core can form a superposed battery. The core structure can avoid gaps in the corners inside the battery core, so that the first pole piece in the battery core can effectively and continuously wrap the second pole piece, increasing the stability of the battery core structure. Moreover, since each piece in the first section The number of hollow parts formed by the intervals increases with the increase in the number of surrounding turns. This will undoubtedly waste more active materials and is not conducive to improving the energy density of the battery core. Therefore, compared with the battery core in the related art, Compared to this, the battery core in this embodiment can effectively utilize the internal space of the battery core.

In some embodiments of the present application, the first pole piece includes a first current collector and an active material layer coated on both surfaces of the first current collector, and the second pole piece includes a second current collector and an active material layer coated on both surfaces of the first current collector. In the active material layers on both surfaces, the first current collector extends out of the first tab in the width direction, and the second current collector extends out of the second tab in the width direction. During the charging and discharging process of the battery core, the active material layer coated on the first pole piece and the active material layer coated on the second pole piece react with the electrolyte inside the battery, and the third pole piece connected to the first pole piece reacts with the electrolyte inside the battery. One pole and the second pole connected to the second pole can lead the current formed by the electrochemical reaction to the battery terminal of the battery to form a current loop.

The embodiment of the second aspect of the present application provides a battery cell, which includes the battery core, the casing and the electrolyte in any embodiment of the first aspect. The housing has a cavity for accommodating the battery core, and the electrolyte is filled into the cavity.

In this embodiment, the battery cells may include lithium ion secondary batteries, lithium ion primary batteries, lithium sulfur batteries, sodium lithium ion batteries, sodium ion batteries or magnesium ion batteries, etc., which are not limited in the embodiments of the present application. The battery cell may be in the shape of a cylinder, a flat body, a rectangular parallelepiped or other shapes, and the embodiments of the present application are not limited to this. Battery cells are generally divided into three types according to packaging methods: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application are not limited to this.

According to the battery cell in the embodiment of the present application, since it includes the cell in any embodiment of the first aspect, it also has the beneficial effects of any embodiment of the first aspect. That is to say, because of the battery core in the battery in this embodiment, the first section and the second section of the second pole piece are disconnected at the bending area of the battery core, and the sheet body constituting the first section is disposed on the battery core. The straight area, therefore, in the bending area of the battery core, the position where the first section and the second section are disconnected forms an avoidance part. In this avoidance part, there is no third pole piece corresponding to the first pole piece. diode, therefore, the migration of lithium ions will not occur in this sheltered area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of a large gap between the first pole piece and the second pole piece in the avoidance area, so that the problem of lithium precipitation will not occur. , which can further solve the problem of battery cell safety performance and performance degradation caused by lithium precipitation, thereby improving the performance of battery cells.

The third embodiment of the present application provides a battery, including the battery cell in any embodiment of the second aspect.

According to the battery in the embodiment of the present application, since it has the battery cell in any embodiment of the second aspect, it also has the beneficial effects of any embodiment of the second aspect. That is to say, because of the battery core in the battery in this embodiment, the first section and the second section of the second pole piece are disconnected at the bending area of the battery core, and the sheet body constituting the first section is disposed on the battery core. The straight area, therefore, in the bending area of the battery core, the position where the first section and the second section are disconnected forms an avoidance part. In this avoidance part, there is no third pole piece corresponding to the first pole piece. diode, therefore, the migration of lithium ions will not occur in this sheltered area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of a large gap between the first pole piece and the second pole piece in the avoidance area, so that the problem of lithium precipitation will not occur. , which can further solve the problem of battery cell safety and performance degradation caused by lithium precipitation, thereby improving battery performance.

An embodiment of the fourth aspect of the present application provides an electrical device, including the battery in any embodiment of the third aspect.

According to the electrical equipment in the embodiments of the present application, since it is equipped with the battery in any embodiment of the third aspect, it also has the beneficial effects of any embodiment of the third aspect. That is to say, since the electrical equipment in this embodiment contains the first section and the second section of the second pole piece in the battery core, they are disconnected in the bending area, and the sheet body constituting the first section is disposed on the battery core. The straight area, therefore, in the bending area of the battery core, the position where the first section and the second section are disconnected forms an avoidance part. In this avoidance part, there is no third pole piece corresponding to the first pole piece. diode, therefore, the migration of lithium ions will not occur in this sheltered area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of an excessive gap between the first pole piece and the second pole piece in the avoidance area, so that the problem of lithium precipitation will not be caused. In turn, the problem of battery cell performance degradation caused by lithium precipitation can be solved, thereby improving battery performance and further enabling electrical equipment equipped with the battery to have good endurance and safety performance.

The embodiment of the fifth aspect of the present application provides a method for manufacturing an electric core, which method includes:

Provide the first pole piece, the second pole piece and the isolation film;

Winding the first pole piece, the second pole piece and the separator along the winding direction from the starting end of the winding, and processing it into an electric core including a straight area and bending areas located at both ends of the straight area;;

Wherein, the first pole piece is continuous in the winding direction, the second pole piece includes a first section and a second section arranged sequentially along the winding direction, the first section and the second section are disconnected in the bending area, and the second pole piece The segments are continuous in the winding direction, and the first segment is composed of at least one sheet body, and the sheet body is located in the straight area.

In the battery core manufactured according to the method in the embodiment of the present application, since the first section and the second section of the second pole piece are disconnected in the bending area, the sheet body constituting the first section is arranged in the straight area of the battery core. As a result, in the bending area of the battery core, a space is formed where the first section and the second section are disconnected. In this space, there is no second pole piece corresponding to the first pole piece. Therefore, lithium ion migration does not occur in this sheltered area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of a large gap between the first pole piece and the second pole piece in the avoidance area, so that the problem of lithium precipitation will not occur. , which can then solve the problem of battery cell safety and performance degradation caused by lithium precipitation.

In some embodiments of the present application, before the step of winding the first pole piece, the second pole piece and the isolation film, the manufacturing method further includes: fixing the second section of the second pole piece on the isolation film, Fix the sheet body on the isolation film. Directly fixing the sheet body and the second section to the isolation membrane can effectively fix the second pole piece, avoid the positional deviation of the second pole piece relative to the isolation membrane during the winding process, and effectively ensure the electrical current. The stability of the core structure.

Description of the drawings

In order to explain the technical solutions of the embodiments of the present application more clearly, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. Those of ordinary skill in the art can also obtain other drawings based on the drawings without exerting creative efforts. Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are for the purpose of illustrating preferred embodiments only and are not to be construed as limiting the application. Throughout the drawings, the same reference numbers refer to the same parts. In the attached picture:

Figure 1 is a schematic structural diagram of a vehicle in which the electrical equipment is used in some embodiments of the present application;

Figure 2 is a schematic structural diagram of a battery according to some embodiments of the present application;

Figure 3 is a schematic diagram of battery cells connected in parallel or in series according to some embodiments of the present application;

Figure 4 is an exploded view of a battery cell according to some embodiments of the present application;

Figure 5 is a schematic structural diagram of a battery core in an embodiment of the present application.

The symbols in the drawings are as follows:

1000-vehicle; 1100-battery; 1110-box; 1111-first part; 1112-second part; 1121-end cover; 1122-casing; 1123-cell assembly; 11231-pole lug; 11211-electrode terminal; 1120-battery cell; 1130-containing cavity; 1200-controller; 1300-motor; 10-winding start end; 20-winding end; 30-straight area; 40-bending area;

100-the first pole piece; 110-the first straight area; 120-the first bending area; 130-the second straight area;

200-second pole piece; 210-first section; 211-piece body; 2111-first piece body; 2112-second piece body; 2113-third piece body; 220-second section;

300-Isolation film;

410-the first pole; 420-the second pole;

M-thickness direction.

Detailed ways

The embodiments of the technical solution of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only used to illustrate the technical solution of the present application more clearly, and are therefore only used as examples and cannot be used to limit the protection scope of the present application.

Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the technical field belonging to this application; the terms used herein are for the purpose of describing specific embodiments only and are not intended to be used in Limitation of this application; the terms "including" and "having" and any variations thereof in the description and claims of this application and the above description of the drawings are intended to cover non-exclusive inclusion.

In the description of the embodiments of this application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying the relative importance or implicitly indicating the quantity or specificity of the indicated technical features. Sequence or priority relationship. In the description of the embodiments of this application, "plurality" means two or more, unless otherwise explicitly and specifically limited.

Reference herein to "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art understand, both explicitly and implicitly, that the embodiments described herein may be combined with other embodiments.

In the description of the embodiments of this application, the term "and/or" is only an association relationship describing associated objects, indicating that there can be three relationships, such as A and/or B, which can mean: A exists alone, and A exists simultaneously and B, there are three cases of B alone. In addition, the character "/" in this article generally indicates that the related objects are an "or" relationship.

In the description of the embodiments of this application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to It is more than two pieces (including two pieces).

In the description of the embodiments of this application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right" and "vertical" The orientation or positional relationships indicated by "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on those shown in the accompanying drawings. The orientation or positional relationship is only for the convenience of describing the embodiments of the present application and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the implementation of the present application. Example limitations.

In the description of the embodiments of this application, unless otherwise clearly stated and limited, technical terms such as "installation", "connection", "connection" and "fixing" should be understood in a broad sense. For example, it can be a fixed connection or a removable connection. It can be disassembled and connected, or integrated; it can be mechanical or electrical; it can be directly connected or indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

In this application, the battery cells may include lithium ion secondary batteries, lithium ion primary batteries, lithium-sulfur batteries, sodium lithium ion batteries, sodium ion batteries or magnesium ion batteries, etc., which are not limited in the embodiments of this application. The battery cell may be in the shape of a cylinder, a flat body, a rectangular parallelepiped or other shapes, and the embodiments of the present application are not limited to this. Battery cells are generally divided into three types according to packaging methods: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application are not limited to this.

The battery mentioned in the embodiments of this application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack. Batteries generally include a box for packaging one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

The battery cell includes a battery core and an electrolyte. The battery core consists of a positive electrode plate, a negative electrode plate and a separator. Battery cells mainly rely on the movement of metal ions between the positive and negative electrodes to work. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode current collector. The positive electrode current collector that is not coated with the positive electrode active material layer protrudes from the positive electrode collector that is coated with the positive electrode active material layer. Fluid, the positive electrode current collector without the positive electrode active material layer is used as the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganate, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode current collector that is not coated with the negative electrode active material layer protrudes from the negative electrode collector that is coated with the negative electrode active material layer. Fluid, the negative electrode current collector that is not coated with the negative electrode active material layer serves as the negative electrode tab. The material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon or silicon. In order to ensure that large currents can pass through without melting, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together. The material of the isolation film can be PP (polypropylene, polypropylene) or PE (polyethylene, polyethylene), etc. In addition, the battery core may have a wound structure or a laminated structure, and the embodiments of the present application are not limited thereto.

Lithium-ion batteries have been widely used in various electronic devices due to their high energy density and low environmental pollution. As the market's requirements for fast charging and rapid regeneration of lithium-ion batteries continue to increase, how to further improve battery cell performance has become an urgent problem that needs to be solved.

In the related art, a battery cell is formed by winding a positive electrode sheet, a negative electrode sheet and a separator. Specifically, after the positive electrode sheet, negative electrode sheet and separator are wound to form a rolled body, The winding body needs to be pressed into a flat shape so that the battery core finally presents a racetrack-shaped structure including straight areas and bent areas. The inventor of the present application found through research that during the process of pressing the winding body into a flat structure, the positive electrode piece and the negative electrode piece in the several turns of the winding layer near the winding center are prone to produce relatively large friction in the bending area. Large gaps. The existence of these gaps can easily cause the problem of lithium precipitation, which in turn leads to a decrease in battery cell performance. In order to improve the above problems, the applicant developed an electric core. The electric core includes a first pole piece, a second pole piece and an isolation film located between the first pole piece and the second pole piece. The three are wound along Directional winding to form a battery core. Wherein, the first pole piece is continuous in the winding direction, and the second pole piece includes a first section and a second section arranged sequentially along the winding direction. Moreover, the first section and the second section are disconnected in the bending area of the battery core, and the second section is continuous in the winding direction. The first section is composed of at least one sheet body, and the sheet body is located in the straight area of the battery core. Since the first section and the second section of the second pole piece are disconnected in the bending area of the battery core, and the sheet body constituting the first section is arranged in the straight area of the battery core, therefore, in the bending area of the battery core , the position where the first section and the second section are disconnected forms an avoidance part. In this avoidance part, there is no second pole piece corresponding to the first pole piece. Therefore, there will be no occurrence in this avoidance part. Deintercalation of lithium ions. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of a large gap between the first pole piece and the second pole piece in the avoidance area, thereby reducing the possibility of lithium precipitation in the bending area. properties, thereby improving the problem of battery cell safety and performance degradation caused by lithium precipitation.

The technical solutions described in the embodiments of this application are applicable to batteries and electrical equipment using batteries.

Power-consuming devices can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys and power tools, etc. Vehicles can be fuel vehicles, gas vehicles or new energy vehicles, and new energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles, etc.; spacecraft include aircraft, rockets, space shuttles, spaceships, etc.; electric toys include fixed Type or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.; electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, for example, Electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, planers and more. The embodiments of this application impose no special restrictions on the above electrical equipment.

For the convenience of explanation in the following embodiments, an electrical device according to an embodiment of the present application is a vehicle 1000 as an example.

Please refer to FIG. 1 , which is a schematic structural diagram of a vehicle 1000 provided by some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. The battery 1100 is disposed inside the vehicle 1000 , and the battery 1100 may be disposed at the bottom, head, or tail of the vehicle 1000 . The battery 1100 may be used to power the vehicle 1000 , for example, the battery 1100 may serve as an operating power source for the vehicle 1000 . The vehicle 1000 may also include a controller 1200 and a motor 1300. The controller 1200 is used to control the battery 1100 to provide power to the motor 1300, for example, for the starting, navigation and operating power requirements of the vehicle 1000 when driving.

In some embodiments of the present application, the battery 1100 can not only be used as an operating power source of the vehicle 1000, but also can be used as a driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

In some embodiments, see FIG. 2 and FIG. 3 . FIG. 2 is a schematic structural diagram of a battery 1100 disclosed in some embodiments of the present application, and FIG. 3 is a schematic diagram of battery cells connected in parallel or in series according to some embodiments of the present application. The battery 1100 includes a case 1110 and a battery cell 1120. The case 1110 is used to accommodate the battery cell 1120.

The box body 1110 may include a first part 1111 and a second part 1112. The first part 1111 and the second part 1112 cover each other to define an accommodation cavity 1130 for accommodating the battery cell 1120. The first part 1111 and the second part 1112 can be in various shapes, such as cuboid, cylinder, etc. The first part 1111 may be a hollow structure open on one side, and the second part 1112 may also be a hollow structure open on one side. The open side of the second part 1112 is covered with the open side of the first part 1111 to form an accommodating cavity 1130. Box 1110. As shown in FIG. 2 , the first part 1111 may be a hollow structure with one side open, the second part 1112 may be a plate-like structure, and the second part 1112 covers the open side of the first part 1111 to form a receiving cavity 1130 . Box 1110. For example, in Figure 2, both the first part 1111 and the second part 1112 are rectangular parallelepiped structures.

The first part 1111 and the second part 1112 can be sealed by sealing elements, which can be sealing rings, sealants, etc.

In the battery 1100, there may be one battery cell 1120 or a plurality of battery cells 1120. If there are multiple battery cells 1120 , the multiple battery cells 1120 can be connected in series, in parallel, or in mixed connection. Mixed connection means that the multiple battery cells 1120 are both connected in series and in parallel. Multiple battery cells 1120 may be first connected in series, parallel, or mixed to form a battery module, and then multiple battery modules may be connected in series, parallel, or mixed to form a whole, and be accommodated in the box 1110 . It is also possible that all the battery cells 1120 are directly connected in series or in parallel or mixed together, and then the whole battery cells 1120 are accommodated in the box 1110 .

Referring to Figure 4, this application discloses a battery cell 1120. Figure 4 is an exploded view of a battery cell 1120 disclosed in some embodiments of the present application. The battery cell 1120 refers to the smallest unit that constitutes the battery 1100. As shown in FIG. 4 , the battery cell 1120 includes an end cover 1121 , a housing 1122 , a cell assembly 1123 and other functional components.

The end cap 1121 refers to a component that covers the opening of the housing 1122 to isolate the internal environment of the battery cell 1120 from the external environment. Without limitation, the shape of the end cap 1121 may be adapted to the shape of the housing 1122 to fit the housing 1122 . In some embodiments, the end cap 1121 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 1121 is less likely to deform when subjected to extrusion and collision, so that the battery cell 1120 can have better performance. With high structural strength, safety performance can also be improved. Functional components such as electrode terminals 11211 may be provided on the end cap 1121 . The electrode terminal 11211 can be used to electrically connect with the battery cell assembly 1123 for outputting or inputting electrical energy of the battery cell 1120. In some embodiments, the end cap 1121 may also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 1120 reaches a threshold. The end cap 1121 can also be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which are not particularly limited in the embodiment of the present application. In some embodiments, an insulating member may also be provided inside the end cover 1121, and the insulating member may be used to isolate the electrical connection components in the housing 1122 from the end cover 1121 to reduce the risk of short circuit. For example, the insulating member may be plastic, rubber, etc.

The housing 1122 is a component used to cooperate with the end cover 1121 to form an internal environment of the battery cell 1120, wherein the formed internal environment can be used to accommodate the battery core assembly 1123, electrolyte and other components. The housing 1122 and the end cover 1121 may be independent components, and an opening may be provided on the housing 1122. The end cover 1121 covers the opening at the opening to form the internal environment of the battery cell 1120. Without limitation, the end cap 1121 and the shell 1122 can also be integrated. In some embodiments, the end cap 1121 and the shell 1122 can form a common connection surface before other components are put into the shell. When the shell needs to be packaged 1122, the end cover 1121 is then closed to cover the housing 1122. The housing 1122 may be of various shapes and sizes, such as rectangular parallelepiped, cylinder, hexagonal prism, etc. In some embodiments, the shape of the housing 1122 may be determined according to the specific shape and size of the cell assembly 1123 . The housing 1122 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which are not particularly limited in the embodiment of the present application.

As shown in Figure 5, the battery core proposed according to the embodiment of the first aspect of the present application includes a first pole piece 100, a second pole piece 200, and an isolation device between the first pole piece 100 and the second pole piece 200. The film 300 and the three are wound along the winding direction to form an electric core. The battery core includes a straight area 30 and bent areas 40 located at both ends of the straight area 30. The first pole piece 100 is continuous in the winding direction, and the second pole piece 200 includes first sections 210 arranged sequentially along the winding direction. and a second section 220, wherein the first section 210 and the second section 220 are disconnected in the bending area 40, and the second section 220 is continuous in the winding direction. The first section 210 is composed of at least one sheet body 211. The body 211 is located in the flat area 30.

As shown in FIG. 4 , the battery core may also be referred to as the battery core assembly 1123 , which is the component in the battery cell 1120 where electrochemical reactions occur. One or more battery core assemblies 1123 may be contained within the housing 1122 . The cell assembly 1123 is mainly formed by winding or stacking positive electrode sheets and negative electrode sheets, and a separator is usually provided between the positive electrode sheets and the negative electrode sheets. The portions of the positive electrode sheet and the negative electrode sheet that contain active material constitute the main body of the battery cell assembly, and the portions of the positive electrode sheet and the negative electrode sheet that do not contain active material constitute the tabs 11231 respectively. The positive electrode tab and the negative electrode tab can be located together at one end of the main body or respectively located at both ends of the main body. During the charging and discharging process of the battery, the positive active material and the negative active material react with the electrolyte, and the tab 11231 is connected to the electrode terminal to form a current loop.

In some embodiments, the first pole piece 100 is a negative pole piece, and the second pole piece 200 is a positive pole piece. The pole piece usually includes a current collector and an active material layer coated on both sides of the current collector. The current collector is a structure that collects current. For example, it can be copper foil, aluminum foil, etc.

The isolation film 300 is an important part of the battery core and is used to insulate the first pole piece 100 and the second pole piece 200 to prevent short circuit. The isolation film 300 is made of insulating material. In some embodiments, the isolation film 300 may be made of polyethylene, polypropylene, or the like.

The first pole piece 100 , the second pole piece 200 and the isolation film 300 are wound from the winding starting end 10 along the winding direction to form an electric core, where the winding direction is winding along the extension direction of the pole pieces from the winding starting end 10 to the winding end 10 . End 20 direction. When the winding is completed, the winding start end 10 is located on the innermost ring of the battery core, and the other end opposite to the winding start end 10 is the winding end 20 , and the winding end 20 is located on the outermost ring of the battery core.

After the first pole piece 100 , the second pole piece 200 and the isolation film 300 are rolled to form a rolled body, the rolled body needs to be pressed into a flat shape to finally form an elliptical electric core. For a battery core with a racetrack-shaped end surface, the flat area 30 refers to the flat part near the middle of the battery core. In the flat area 30 , both the first pole piece 100 and the second pole piece 200 are in a straight state. ; The bending area 40 refers to the portion of the battery core that is curved in appearance near both ends. In the bending area 40, the first pole piece 100 and/or the second pole piece 200 are in a bent state.

The sheet body 211 can also be understood as a sheet-shaped pole piece structure. The sheet body 211 can be obtained after cutting the pole piece. The sheet body 211 is located in the flat area 30. Therefore, in the wound battery core, the sheet body 211 is flat. straight state.

According to the battery core in the embodiment of the present application, the rolled battery core includes a straight area 30 and a bent area 40. The first section 210 and the second section 220 of the second pole piece 200 are in the bent area of the battery core. 40 is disconnected, and the piece 211 constituting the first section 210 is arranged in the straight area 30 of the battery core. Therefore, in the bent area 40 of the battery core, the position where the first section 210 and the second section 220 are disconnected forms a In the sheltered area, there is no second pole piece 200 corresponding to the first pole piece 100. Therefore, lithium ion migration does not occur in this sheltered area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of a large gap between the first pole piece 100 and the second pole piece 200 in the avoidance area, so that lithium precipitation will not occur. problem, which can then solve the problem of battery cell safety and performance degradation caused by lithium precipitation.

In some embodiments of the present application, the first section 210 includes a plurality of pieces 211 , and each piece 211 is spaced apart along the winding direction and is located in the flat area 30 .

The sheet bodies 211 are spaced apart along the winding direction, and the sheet bodies 211 can be connected to the isolation film 300 through a composite fixation method, such as glue coating, gluing, extrusion, heating, etc.

In the related art, a hollow structure is usually formed at the center of the wound battery core. In this embodiment, the second pole piece 200 includes a first section 210 and a second section 220 arranged sequentially along the winding direction, and the first section 210 includes a plurality of sheet bodies 211 arranged spaced apart from each other. The plurality of sheet bodies 211 A plurality of avoidance parts located in the bending area 40 can be formed, thereby better improving the lithium deposition problem in the inner ring bending area 40 and thereby improving the capacity and performance of the battery core.

In some embodiments of the present application, multiple sheets 211 are arranged in parallel in the thickness direction M of the battery core.

The thickness direction M of the battery core is consistent with the thickness direction of the first pole piece 100 or the second pole piece 200. Since the pole piece is an aluminum foil piece, its thickness direction M is a direction perpendicular to the plane of the pole piece.

In this embodiment, the plurality of sheet bodies 211 are disconnected from each other and arranged in parallel in the thickness direction M of the battery core. At this time, a part of the first pole piece 100 is wound with each sheet body 211. In this way, the plurality of sheet bodies 211 are wound together. The individual piece body 211 and part of the first pole piece 100 can well fill the space near the center of the battery core, making the internal space of the battery core more compact and further increasing the capacity of the battery core.

In some embodiments of the present application, the projections of each sheet 211 in the thickness direction M of the battery core are arranged opposite to each other.

The projection of each sheet 211 in the thickness direction M is to project the plurality of sheets 211 along the thickness direction M of the battery core. The projections of each sheet 211 are arranged opposite to each other, which means that the projections of these sheets 211 basically overlap. It should be pointed out that the projected areas of each sheet 211 do not necessarily overlap completely. For example, the ratio of the overlapping area projected by each sheet 211 to the total projected area of each sheet 21 may be more than 80%. In this embodiment No special restrictions are made.

In this embodiment, by arranging the projections of the respective sheets 211 in the cell thickness direction M relative to each other, it is more conducive to align the respective sheets 211 in the battery core compared to staggering the respective sheets 211 . The flat area 30 occupies as large an area as possible, which is beneficial to increasing the area of the active material layer in the battery core, thereby increasing the energy density of the battery core per unit area.

In some embodiments of the present application, from the winding starting end 10 , the first pole piece 100 includes a first straight area 110 , a first bending area 120 and a second straight area 130 in sequence, and the sheet body 211 includes the first sheet Body 2111, in the thickness direction M of the battery core, the first sheet body 2111 is arranged corresponding to the first straight area 110, and the first sheet body 2111 is located on the side of the first straight area 110 away from the second straight area 130 , the projection of the first sheet 2111 is completely located within the projection of the first flat area 110 .

In this embodiment, the first sheet body 2111 is located on the side of the first straight area 110 away from the second straight area 130, and the first straight area 110 is close to the winding start end 10 of the battery core. That is to say, on During the winding process of the battery core, the first pole piece 100 is first bent, and then the first piece body 2111 is placed on the side of the first straight area 110 away from the second straight area 130. Therefore, when winding When the wound battery core is pressed and shaped, it is possible to prevent the first pole piece 100 from being displaced in position and creating a gap, which affects the performance of the battery. Moreover, the projection of the first sheet body 2111 is located within the projection of the first straight area 110. That is to say, the bending areas 40 at both ends of the first sheet body 2111 are only formed with the first pole piece 100 and the isolation film 300. During the process of pressing the winding body into a flat structure, there is no migration problem of lithium ions from the first pole piece 100 and the second pole piece 200 in this part, so the problem of lithium precipitation will not be caused, and the problem can be solved. The problem of battery performance degradation caused by lithium precipitation.

In some embodiments of the present application, the sheet body 211 also includes a second sheet body 2112. In the thickness direction M, the second sheet body 2112 is arranged corresponding to the first straight area 110, and the second sheet body 2112 is located in the first flat area 110. between the straight area 110 and the second straight area 130.

In this embodiment, the second sheet body 2112 is disposed between the first straight area 110 and the second straight area 130. In this way, the second sheet body 2112 can well fill the space near the center of the battery core. This makes the internal space of the battery core more compact, further increases the capacity of the battery core, and reduces the waste of active material on the first pole piece 100 .

In some embodiments of the present application, the sheet body 211 also includes a third sheet body 2113. In the thickness direction M of the battery core, the third sheet body 2113 is arranged corresponding to the second straight area 130, and the third sheet body 2113 Located on the side of the second straight area 130 away from the first straight area 110 .

In this embodiment, the first piece 2111 is disposed on the side of the first straight area 110 away from the second straight area 130 , and the third piece 2113 is disposed on the second straight area 130 away from the first straight area 110 side, and the first bending area 120 is located between the first straight area 110 and the second straight area 130. In this way, at least the first bending area 120 can form an avoidance part, and in this avoidance part , there is no second pole piece 200 arranged corresponding to the first pole piece 100, therefore, the migration of lithium ions will not occur in this avoidance part. During the process of pressing the winding body into a flat structure, in the avoidance part, There is no gap problem between the first pole piece 100 and the second pole piece 200 in the empty part, so the problem of lithium precipitation will not be caused, and the problem of battery cell performance degradation caused by lithium precipitation can be solved.

In some embodiments of the present application, the first section 210 wraps up to three times in the winding direction.

In this embodiment, the first pole piece 100, the second pole piece 200 and the isolation film 300 are wound along the winding direction from the winding starting end 10 to form a battery core. The pole pieces 200 are all the first section 210 of the second pole piece 200. That is to say, the three circles located in the center of the battery core are all sheet bodies 211. These sheet bodies 211 are disconnected from each other and are located in the flat area 30 of the battery core. , one end of the sheet body 211 close to the second section 220 is disconnected from the second section 220 of the second pole piece 200 in the bending area 40 . In the related art, the corner of the innermost ring of the battery core is the most serious part of the lithium deposition problem. In this embodiment, when the wound battery core is compressed and shaped, the center part of the battery core can form a superposed battery. The core structure can avoid gaps in the corners inside the battery core, so that the first pole piece 100 in the battery core can effectively and continuously wrap the second pole piece 200, increasing the structural stability of the battery core. Moreover, since the first section 210 The number of hollows formed between the sheets 211 increases as the number of circles increases, which will undoubtedly waste more active material and is not conducive to improving the energy density of the battery core. Therefore, compared with the battery cells in the related art, the battery core in this embodiment can effectively utilize the internal space of the battery core and increase the energy density of the battery core per unit volume.

In some embodiments of the present application, the first pole piece 100 includes a first current collector and active material layers coated on both surfaces of the first current collector, and the second pole piece 200 includes a second current collector and a second current collector coated on both surfaces. In the active material layers on both surfaces of the current collector, the first current collector extends out of the first tab 410 in the width direction, and the second current collector extends out of the second tab 420 in the width direction.

The first pole tab 410 and the second pole tab 420 are parts of the positive electrode piece and the negative electrode piece that do not contain active material. In some embodiments, the first pole piece 100 includes a first current collector and two parts coated on the first current collector. The active material layer on the surface of the second pole piece 200 includes a second current collector and an active material layer coated on both surfaces of the second current collector. The first current collector extends out of the first tab 410 in the width direction. The fluid extends out of the second pole tab 420 in the width direction, wherein the active material layer coated on the surface of the first pole piece 100 and the active material layer coated on the surface of the second pole piece 200 have opposite polarities, for example, the first The pole piece 100 can be coated with a positive active material, and the second pole piece 200 can be coated with a negative active material, or the first pole piece 100 can be coated with a negative active material, and the second pole piece 200 can be coated with a positive active material. In related art, the number of first poles 410 and second poles 420 may be multiple, and multiple poles of the same polarity may be arranged in parallel. For example, the first pole 410 may include multiple first poles. Sub-pole tabs, each first sub-pole tab is connected to a different roll layer of the first pole piece 100 respectively, the second pole tab 420 may include a plurality of second sub-pole tabs, each second sub-pole tab is connected to the second section 220 respectively. Different roll layers and different sheets 211 of the first section 210 are connected. The first tab 410 and the second tab 420 can be welded to the adapter of the battery by ultrasonic welding, and then the adapter is welded to the top cover of the battery cell by laser welding to realize the battery circuit.

In this embodiment, during the charging and discharging process of the battery cell, the active material layer coated on the first pole piece 100 and the active material layer coated on the second pole piece 200 react with the electrolyte inside the battery. The first tab connected to the first pole piece and the second tab connected to the second pole piece can lead the current formed by the electrochemical reaction to the battery terminal of the battery to form a current loop.

In some embodiments of the present application, the battery core includes a first pole piece 100, a second pole piece 200, and an isolation film 300 located between the first pole piece 100 and the second pole piece 200. The three pole pieces start from the winding start end 10 It is wound along the winding direction to form an electric core. The battery core includes a straight area 30 and bent areas 40 located at both ends of the straight area 30. The first pole piece 100 is continuous in the winding direction, and the second pole piece 200 includes first sections 210 arranged sequentially along the winding direction. and a second section 220, wherein the first section 210 and the second section 220 are disconnected in the bending area 40, and the second section 220 is continuous in the winding direction. The first section 210 is composed of a plurality of sheets 211, The plurality of sheets 211 are arranged in parallel in the thickness direction M of the battery core, and the projections of the sheets 211 in the thickness direction M of the battery core are arranged opposite to each other. The sheets 211 are spaced apart along the winding direction and are all located on a straight District 30. From the winding starting end 10, the first pole piece 100 includes a first straight area 110, a first bending area 120 and a second straight area 130 in sequence, and the sheet body 211 includes a first sheet body 2111, a second sheet body 2112 and The third sheet body 2113. In the thickness direction M of the battery core, the first sheet body 2111 is arranged corresponding to the first straight area 110, and the first sheet body 2111 is located in the first straight area 110 away from the second straight area 130. On one side, the projection of the first sheet 2111 is completely located within the projection of the first straight area 110, the second sheet 2112 is arranged corresponding to the first straight area 110, and the second sheet 2112 is located in the first straight area Between 110 and the second straight area 130, a third piece 2113 is provided corresponding to the second straight area 130, and the third piece 2113 is located on the side of the second straight area 130 away from the first straight area 110. Along the winding direction, the first section 210 can wrap around at most three times. The first pole piece 100 includes a first current collector and an active material layer coated on both surfaces of the first current collector, and the second pole piece 200 includes a second current collector and an active material layer coated on both surfaces of the second current collector, The first current collector extends out of the first tab 410 in the width direction, and the second current collector extends out of the second tab 420 in the width direction.

According to the battery core in the embodiment of the present application, the rolled battery core includes a straight area 30 and a bent area 40. The first section 210 and the second section 220 of the second pole piece 200 are in the bent area of the battery core. 40 is disconnected, and the piece 211 constituting the first section 210 is arranged in the straight area 30 of the battery core. Therefore, in the bent area 40 of the battery core, the position where the first section 210 and the second section 220 are disconnected forms a In the sheltered area, there is no second pole piece 200 provided corresponding to the first pole piece 100. Therefore, migration of lithium ions does not occur in this sheltered area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of a large gap between the first pole piece 100 and the second pole piece 200 in the avoidance area, so that analysis will not occur. The problem of lithium can then solve the problem of battery cell performance degradation caused by lithium precipitation.

In some embodiments, by arranging the projections of each sheet 211 in the cell thickness direction M relative to each other, the flat area 30 of the cell can accommodate more sheets 211 , which can increase more chemical reactions. layer to increase the energy density of the cell per unit area. Since the battery core in this embodiment is provided with the second sheet body 2112 between the first straight area 110 and the second straight area 130, the second sheet body 2112 can well fill the gap near the center of the battery core. space, making the internal space of the battery core more compact, further increasing the capacity of the battery core, and reducing the waste of active material on the first pole piece 100. Moreover, since the first sheet body 2111 is disposed on the side of the first straight area 110 away from the second straight area 130, the third sheet body 2113 is disposed on the side of the second straight area 130 away from the first straight area 110. , and the first bending area 120 is located between the first straight area 110 and the second straight area 130. In this way, at least the first bending area 120 can form an avoidance part, and in this avoidance part, there is no The second pole piece 200 is provided corresponding to the first pole piece 100. Therefore, lithium ion migration will not occur in the sheltered area. During the process of pressing the winding body into a flat structure, there will be no lithium ion migration in the sheltered area. The problem of a gap between the first pole piece 100 and the second pole piece 200 will not cause the problem of lithium precipitation, thereby solving the problem of battery cell performance degradation caused by lithium precipitation.

Furthermore, during the charging and discharging process of the battery cell, the active material layer coated on the first pole piece 100 and the active material layer coated on the second pole piece 200 react with the electrolyte inside the battery and react with the first pole piece 100 . The first tab connected to the pole piece and the second tab connected to the second pole piece can lead the current formed by the electrochemical reaction to the battery terminal of the battery to form a current loop.

According to the battery cell in the embodiment of the present application, since it includes the cell in any embodiment of the first aspect, it also has the beneficial effects of any embodiment of the first aspect. That is to say, due to the battery core in the battery in this embodiment, the first section 210 and the second section 220 of the second pole piece 200 are disconnected at the bending area 40 of the battery core, forming the sheet body of the first section 210 211 is disposed in the flat area 30 of the battery core. Therefore, in the bending area 40 of the battery core, a space is formed where the first section 210 and the second section 220 are disconnected. In this space, there is no The second pole piece 200 is provided corresponding to the first pole piece 100. Therefore, lithium ion migration will not occur in the avoidance area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of a large gap between the first pole piece 100 and the second pole piece 200 in the avoidance area, so that lithium precipitation will not occur. The problem of battery cell safety and performance degradation caused by lithium precipitation can be solved, thereby improving the performance of battery cells.

In this embodiment, the battery may include a case and a battery cell, and the battery cell is accommodated in the case. Among them, the box is used to provide accommodating space for the battery cells, and the box can adopt a variety of structures. In some embodiments, the box may include a first part and a second part, the first part and the second part cover each other, and the first part and the second part jointly define an accommodation space for accommodating battery cells. The second part may be a hollow structure with one end open, and the first part may be a plate-like structure, and the first part covers the open side of the second part, so that the first part and the second part jointly define an accommodation space; the first part and the second part The parts may also be hollow structures with one side open, and the open side of the first part is covered with the open side of the second part. Of course, the box formed by the first part and the second part can be in various shapes, such as cylinder, rectangular parallelepiped, etc.

Since the battery in this embodiment has the battery cell in any embodiment of the second aspect, it also has the beneficial effects of any embodiment of the second aspect. Specifically, in this embodiment, after winding and forming, The battery core includes a straight area 30 and a bending area 40. The first section 210 and the second section 220 of the second pole piece 200 are disconnected at the bending area 40 of the battery core, and the sheet body 211 constituting the first section 210 is provided In the straight area 30 of the battery core, and therefore in the bent area 40 of the battery core, an escape location is formed where the first section 210 and the second section 220 are disconnected. In this void area, there is no connection with the third section. One pole piece 100 is provided correspondingly to the second pole piece 200. Therefore, migration of lithium ions will not occur in the avoidance area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of an excessive gap between the first pole piece 100 and the second pole piece 200 in the avoidance area, thereby not causing lithium precipitation. This can further solve the problem of battery cell performance degradation caused by lithium precipitation, thereby improving battery performance.

The fourth aspect embodiment of the present application provides an electrical device, including the battery in the third aspect embodiment.

Embodiments of the present application provide an electrical device that uses a battery as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, spaceships, etc.

According to the electrical equipment in the embodiment of the present application, since it has the battery in the embodiment of the third aspect, it also has the beneficial effects of any embodiment of the third aspect. Specifically, in this embodiment, the winding The formed battery core includes a straight area 30 and a bending area 40. The first section 210 and the second section 220 of the second pole piece 200 are disconnected at the bending area 40 of the battery core to form the sheet body of the first section 210. 211 is disposed in the flat area 30 of the battery core. Therefore, in the bending area 40 of the battery core, a space is formed where the first section 210 and the second section 220 are disconnected. In this space, there is no The second pole piece 200 is provided corresponding to the first pole piece 100. Therefore, migration of lithium ions does not occur in the avoidance area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of an excessive gap between the first pole piece 100 and the second pole piece 200 in the avoidance area, thereby not causing lithium precipitation. This can further solve the problem of battery cell performance degradation caused by lithium precipitation. Therefore, electrical equipment that uses this battery as a power source can also obtain better battery cell performance.

Provide a first pole piece 100, a second pole piece 200 and an isolation film 300;

The first pole piece 100 , the second pole piece 200 and the isolation film 300 are wound along the winding direction from the winding starting end, and processed into an electrode including a straight area 30 and bent areas 40 located at both ends of the straight area 30 . core;

Among them, the first pole piece 100 is continuous in the winding direction, and the second pole piece 200 includes a first section 210 and a second section 220 arranged sequentially along the winding direction. The first section 210 and the second section 220 are in the bending area. 40 is disconnected, and the second section 220 is continuous in the winding direction. The first section 210 is composed of at least one sheet body 211, and the sheet body 211 is located in the straight area 30.

When manufacturing the battery core in this embodiment, it is necessary to wind the first pole piece 100 , the second pole piece 200 and the isolation film 300 along the winding direction. The sheet body 211 of 200 and the isolation film 300 are wound along the winding direction. Next, the first pole piece 100, the second section 220 of the second pole piece 200 and the isolation film 300 are wound along the winding direction. After completion After winding, the wound battery core can be compressed and shaped so that the sheet body 211 is located in the flat area 30 of the battery core, and a part of the second section 220 close to the first section 210 is also located in the flat area 30 .

According to the battery core manufactured according to the embodiment of the present application, the wound battery core includes a straight area 30 and a bending area 40. The first section 210 and the second section 220 of the second pole piece 200 are in the bending area of the battery core. 40 is disconnected, and the piece 211 constituting the first section 210 is arranged in the straight area 30 of the battery core. Therefore, in the bent area 40 of the battery core, the position where the first section 210 and the second section 220 are disconnected forms a In the sheltered area, there is no second pole piece 200 provided corresponding to the first pole piece 100. Therefore, migration of lithium ions does not occur in this sheltered area. Therefore, in the process of pressing the winding body into a flat structure, there is no problem of an excessive gap between the first pole piece 100 and the second pole piece 200 in the avoidance area, thereby not causing lithium precipitation. problem, which can then solve the problem of battery cell performance degradation caused by lithium precipitation.

In some embodiments of the present application, before the step of winding the first pole piece 100, the second pole piece 200 and the isolation film 300, the manufacturing method further includes:

The second section 220 of the second pole piece 200 is fixed on the isolation film 300 , and the sheet body 211 is fixed on the isolation film 300 .

The method of fixing the sheet body 211 and the second section 220 to the isolation film 300 may be glue coating, pasting, extrusion, heating, etc.

In this embodiment, the sheet body 211 and the second section 220 are directly fixed on the isolation film 300, which can effectively realize the fixation of the second pole piece 200 and avoid the second pole piece 200 relative to the winding process. The position of the isolation film 300 is shifted, effectively ensuring the structural stability of the battery core.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present application. The scope shall be covered by the claims and description of this application. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any way. The application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

An electric core, including: a first pole piece, a second pole piece and an isolation film located between the first pole piece and the second pole piece, the three of which are wound along the winding direction to form the electric core ; The battery core includes a straight area and bending areas located at both ends of the straight area, the first pole piece is continuous in the winding direction, and the second pole piece includes successive pole pieces along the winding direction. The first and second paragraphs of the setting;

Wherein, the first section and the second section are disconnected in the bending area, and the second section is continuous in the winding direction, and the first section is composed of at least one sheet body, so The sheet body is located in the flat area.
The battery core according to claim 1, wherein the first section includes a plurality of the sheet bodies, and each of the sheet bodies is spaced apart along the winding direction and is located in the flat area.
The battery core according to claim 2, wherein a plurality of the sheets are arranged in parallel in the thickness direction of the battery core.
The battery core according to claim 2 or 3, wherein the projections of each of the sheets in the thickness direction of the battery core are arranged opposite to each other.
The battery core according to claim 1, wherein along the winding direction, from the starting end of the first pole piece, the first pole piece sequentially includes a first straight area, a first bent area and a third Two straight areas, the sheet body includes a first sheet body, the first sheet body is arranged corresponding to the first straight area in the thickness direction of the battery core, and the first sheet body is located The first straight area is on one side away from the second straight area, and the projection of the first sheet is completely located within the projection of the first straight area.
The battery core according to claim 5, wherein the sheet body further includes a second sheet body, the second sheet body is disposed corresponding to the first straight area in the thickness direction, and the The second piece is located between the first straight area and the second straight area.
The battery core according to claim 5 or 6, wherein the sheet body further includes a third sheet body, and the third sheet body corresponds to the second straight area in the thickness direction of the battery core. is arranged, and the third piece is located on the side of the second straight area away from the first straight area.
The battery core according to any one of claims 1 to 7, wherein the first section is wound around at most three times along the winding direction.
The battery core according to any one of claims 1 to 8, wherein the first pole piece includes a first current collector and active material layers coated on both surfaces of the first current collector, and the second pole piece The sheet includes a second current collector and an active material layer coated on both surfaces of the second current collector. The first current collector extends out of the first tab in the width direction, and the second current collector extends in the width direction. Extend the second pole.
A battery cell, including: the battery core according to any one of claims 1-9;

A housing with a cavity for accommodating the battery core;

Electrolyte, the electrolyte fills the cavity.
A battery including the battery cell according to claim 10.
An electrical device including the battery according to claim 11.
A method of manufacturing an electric core, including:

Provide the first pole piece, the second pole piece and the isolation film;

The first pole piece, the second pole piece and the isolation film are rolled along the winding direction and processed into an electric core including a straight area and bent areas located at both ends of the straight area;

Wherein, the first pole piece is continuous in the winding direction, and the second pole piece includes a first section and a second section arranged sequentially along the winding direction, and the first section and the second section are located in the winding direction. The bending area is disconnected, and the second section is continuous in the winding direction. The first section is composed of at least one sheet body, and the sheet body is located in the straight area.
The manufacturing method of an electric core according to claim 13, wherein before the step of winding the first pole piece, the second pole piece and the isolation film in the winding direction, the manufacturing method further include:

The second section of the second pole piece is fixed on the isolation membrane, and the sheet body is fixed on the isolation membrane.