Battery monomer, battery and electric device

Abstract

The invention provides a battery monomer, a battery and a power utilization device, and belongs to the technical field of batteries. The battery monomer comprises a first pole piece, a diaphragm and a plurality of second pole pieces; a plurality of structure weakening areas extending in the width direction of the first pole piece are arranged on the first pole piece; the diaphragm covers the surfaces of the two opposite sides of the first pole piece; the multiple second pole pieces are alternately arranged on the diaphragms on the two opposite sides of the first pole piece, every two adjacent second pole pieces are located on the different sides of the first pole piece in the length direction of the first pole piece, and a corresponding structure weakening area exists between every two adjacent second pole pieces; wherein the first pole piece is folded at the plurality of structure weakening areas, so that the first pole piece and the plurality of second pole pieces are alternately stacked with each other.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery and an electrical device. Background Art

[0002] Energy conservation and emission reduction are the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their advantages in energy conservation and environmental protection. For electric vehicles, battery technology is an important factor in their development.

[0003] However, the performance of battery cells is still difficult to achieve optimal performance, so how to improve the performance of battery cells is a problem that needs to be solved urgently in battery technology. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems existing in the background technology. To this end, one object of the present application is to provide a battery cell, a battery and an electrical device to improve the performance of the battery cell.

[0005] The embodiment of the first aspect of the present application provides a battery cell, which includes a first pole piece, a diaphragm and a plurality of second pole pieces. The first pole piece is provided with a plurality of structurally weakened areas extending along the width direction of the first pole piece; the diaphragm covers the surfaces on the opposite sides of the first pole piece; the plurality of second pole pieces are alternately arranged on the diaphragm on the opposite sides of the first pole piece, wherein, along the length direction of the first pole piece, every two adjacent second pole pieces are located on different sides of the first pole piece, and there is a corresponding structurally weakened area between every two adjacent second pole pieces; wherein the first pole piece is folded at the plurality of structurally weakened areas, so that the first pole piece and the plurality of second pole pieces are alternately stacked on each other.

[0006] In the technical solution of the embodiment of the present application, a plurality of structural weakened areas extending along the width direction of the first pole piece are provided on the first pole piece. Since the mechanical strength of the plurality of structural weakened areas is less than the mechanical strength of the remaining areas of the first pole piece, by providing the plurality of structural weakened areas extending along the width direction of the first pole piece on the first pole piece, the first pole piece can be more easily bent and can be accurately folded at a predetermined position, thereby reducing the misalignment between the first pole piece and the second pole piece and improving the flatness of the first pole piece after folding. Moreover, when the plurality of segments of the first pole piece and the plurality of second pole pieces are alternately stacked with each other, the segments of each two adjacent first pole pieces are connected by the structural weakened area, each two adjacent second pole pieces are located on different sides of the first pole piece, and there is a corresponding structural weakened area between each two adjacent second pole pieces, thereby reducing the gap between the first pole piece and the second pole piece, reducing the lithium deposition problem of the battery cell, and thus improving the performance of the battery cell.

[0007] In some embodiments, the structurally weakened area includes a groove extending along the width direction of the first pole piece. The structurally weakened area includes a groove extending along the width direction of the first pole piece, which has a better effect of guiding the bending of the first pole piece, and the groove can improve the accuracy of the folding position, reduce the misalignment of two adjacent layers of pole pieces in the battery cell after lamination, so that the battery cell has good performance.

[0008] In some embodiments, the structurally weakened area includes two grooves extending along the width direction of the first pole piece, and the two grooves are spaced apart from each other along the length direction of the first pole piece. The structurally weakened area includes two grooves extending along the width direction of the first pole piece, and the two grooves are spaced apart from each other along the length direction of the first pole piece, so that the first pole piece can be folded along the two grooves, making it easier to fold the first pole piece, improving the accuracy of the folding position, and making the segments of the first pole piece aligned with each other, reducing the misalignment between the first pole piece and the second pole piece, thereby further improving the performance of the battery cell.

[0009] In some embodiments, the spacing between the two grooves is greater than or equal to the thickness of the corresponding second pole piece. The first pole piece is folded at multiple structural weakened areas, and the spacing at the formed bends is greater than or equal to the thickness of the second pole piece, so that when multiple segments of the first pole piece and multiple second pole pieces are alternately stacked, the second pole piece will not be squeezed by the first pole piece, and the gap between the first pole piece and the second pole piece at the bend can be reduced, reducing the lithium deposition problem of the battery cell, thereby improving the performance of the battery cell.

[0010] In some embodiments, the length of each groove is less than or equal to the width of the first pole piece. The length of each groove is less than or equal to the width of the first pole piece, which limits the maximum length of the groove. Since the length of the groove does not exceed the width of the first pole piece, the mechanical strength of the structural weakened area can be maintained at a certain level, thereby reducing the probability of the first pole piece breaking during the folding process, and improving the yield rate of battery cell production.

[0011] In some embodiments, the structural weakened area further includes a through hole that penetrates the thickness of the first pole piece. Since the thickness of the first pole piece is relatively thin, the through hole does not need to accurately control the depth, which can reduce the requirements for processing accuracy, and the through hole can greatly weaken the strength of the first pole piece, making it easy to fold.

[0012] In some embodiments, the number N of through holes satisfies: N≥2. Providing multiple through holes can not only weaken the mechanical strength of the first pole piece, but also enable the structural weakened area of ​​the first pole piece to maintain a certain mechanical strength, thereby reducing the possibility of the first pole piece breaking when folding.

[0013] In some embodiments, a plurality of structurally weakened areas are equidistantly spaced from each other along the length direction of the first pole piece. A plurality of structurally weakened areas are equidistantly spaced from each other along the length direction of the first pole piece, and the structurally weakened areas can be located at the bend by setting a suitable spacing distance to weaken the strength of the bend, so that the first pole piece is easier to bend and can be accurately folded at a predetermined position, thereby reducing the misalignment of the multi-layer pole piece and improving the flatness of the first pole piece after folding, thereby improving the performance of the battery cell.

[0014] In some embodiments, the first electrode sheet is an anode electrode sheet, and the second electrode sheet is a cathode electrode sheet. Setting the outermost layer of the battery cell as the anode electrode sheet can reduce the number of layers of the negative electrode sheet after folding, and can make full use of the cathode active material of the cathode electrode sheet.

[0015] An embodiment of the second aspect of the present application provides a method for producing a battery cell, comprising: forming a plurality of structural weakened areas on a first pole sheet, the plurality of structural weakened areas extending along the width direction of the first pole sheet; covering the surfaces on opposite sides of the first pole sheet with a diaphragm; alternately arranging a plurality of second pole sheets on the diaphragms on opposite sides of the first pole sheet, wherein, along the length direction of the first pole sheet, every two adjacent second pole sheets are located on different sides of the first pole sheet, and there is a corresponding structural weakened area between every two adjacent second pole sheets; and folding the first pole sheet at the plurality of structural weakened areas so that the first pole sheet and the plurality of second pole sheets are alternately stacked on each other.

[0016] In the technical solution of the embodiment of the present application, by forming a plurality of structural weakened areas extending along the width direction of the first pole piece on the first pole piece, the first pole piece can be made easier to bend and can be accurately folded at a predetermined position, thereby reducing the misalignment between the first pole piece and the second pole piece and improving the flatness of the first pole piece after folding. In addition, when the plurality of segments of the first pole piece and the plurality of second pole pieces are alternately stacked with each other, the segments of each two adjacent first pole pieces are connected by a structural weakened area, each two adjacent second pole pieces are located on different sides of the first pole piece, and there is a corresponding structural weakened area between each two adjacent second pole pieces, thereby reducing the gap between the first pole piece and the second pole piece, reducing the problem of lithium deposition, and thus improving the performance of the battery cell.

[0017] An embodiment of the third aspect of the present application provides a battery, which includes the battery cell in the above embodiment.

[0018] An embodiment of the fourth aspect of the present application provides an electrical device, which includes the battery in the above embodiment, and the battery is used to provide electrical energy.

[0019] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0021] Figure 1 A schematic diagram of the structure of a vehicle according to some embodiments of the present application;

[0022] Figure 2 A schematic diagram of the exploded structure of a battery according to some embodiments of the present application;

[0023] Figure 3 A schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application;

[0024] Figure 4 This is a schematic structural diagram of a first pole piece in some embodiments of the present application in an unfolded state;

[0025] Figure 5 A schematic diagram of the structure of a battery cell formed by folding in some embodiments of the present application;

[0026] Figure 6 for Figure 4 AA section view in;

[0027] Figure 7 A flow chart of a method for producing a battery cell provided in some embodiments of the present application;

[0028] Figure 8 A schematic diagram of a composite of a first pole piece and a diaphragm in some embodiments of the present application;

[0029] Fig. 9 This is a composite schematic diagram of a first pole piece, a second pole piece, and a diaphragm according to some embodiments of the present application.

[0030] Description of reference numerals:

[0031] 1000. Vehicles;

[0032] 100, battery; 200, controller; 300, motor;

[0033] 10. Box body; 11. First part; 12. Second part;

[0034] 20. Battery cell; 21. End cap; 21a. Electrode terminal; 22. Shell; 23. Cell assembly; 23a. Tab;

[0035] 231. First pole piece; 232. Second pole piece; 233. Diaphragm; 234. Structural weakened area; 235. Groove; 236. Through hole; 237. Roller. DETAILED DESCRIPTION

[0036] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0038] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0039] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0040] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0041] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0042] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0043] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0044] At present, from the perspective of market development, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0045] The structure of a battery usually includes one or more battery cells, that is, a battery cell is the smallest unit of a battery. Among them, multiple battery cells can be connected in series, in parallel, or in mixed connection. Mixed connection means that multiple battery cells are connected in both series and parallel.

[0046] Furthermore, the battery cell is mainly formed by winding or stacking the cathode and anode plates, and a separator is usually provided between the cathode and anode plates. Since the laminated battery cell has the advantages of high rate and high energy density compared with the wound battery cell, and the laminated battery cell can also be made into various special-shaped batteries according to different needs, the laminated battery cell is generally used in the industry to make batteries.

[0047] At present, in the production process of laminated battery cells, continuous pole pieces can be repeatedly folded to form laminated battery cells. However, laminated battery cells are difficult to achieve better performance. One important factor is that during the folding process, the continuous pole pieces are difficult to fold accurately at the predetermined position, resulting in a large amount of misalignment of the multi-layer pole pieces and poor flatness after the pole pieces are folded.

[0048] To this end, it is considered that notches can be set at the folding position to guide the continuous electrode sheet to fold at the predetermined position. However, there is usually only one notch, and the continuous electrode sheet is still difficult to fold normally. At the corner where the continuous electrode sheet is folded, there will be non-overlapping parts between the anode electrode sheet and the cathode electrode sheet. At the same time, the electrode sheet is prone to deflection during the folding process, which causes some lithium ions electrolyzed by the cathode electrode sheet to fail to reach the coating area of ​​the anode electrode sheet active material of the anode electrode sheet facing it, resulting in lithium deposition, and the technical effect of improving the performance of the battery cell is not obvious.

[0049] Based on the above analysis, the present application proposes a battery cell, which includes a first pole piece, a plurality of structurally weakened areas extending along the width direction of the first pole piece are arranged on the first pole piece, the plurality of structurally weakened areas are spaced apart from each other along the length direction of the first pole piece to divide the first pole piece into a plurality of segments, the mechanical strength of the plurality of structurally weakened areas is less than the mechanical strength of the remaining areas of the first pole piece, the surfaces of the first pole piece on opposite sides are covered with a diaphragm; and a plurality of second pole pieces, the plurality of second pole pieces are alternately arranged on the diaphragms on opposite sides of the first pole piece, wherein, along the length direction of the first pole piece, every two adjacent second pole pieces are located on different sides of the first pole piece, and there is a corresponding structurally weakened area between every two adjacent second pole pieces; wherein, the first pole piece is folded at the plurality of structurally weakened areas, so that the plurality of segments of the first pole piece and the plurality of second pole pieces are alternately stacked with each other. The battery cell can be accurately folded at a predetermined position, the misalignment of the multilayer pole piece is reduced, the flatness of the first pole piece after folding is improved, and the gap between the first pole piece and the second pole piece is reduced, the problem of lithium deposition is reduced, and the performance of the battery cell is improved.

[0050] The battery cell disclosed in the embodiment of the present application can be used in, but not limited to, electric devices such as vehicles, ships or aircraft. A power supply system comprising the battery cell and battery disclosed in the present application can be used to form the electric device, which is beneficial to reduce the misalignment of the multi-layer pole piece and improve the flatness of the first pole piece after folding, thereby improving the performance of the battery cell.

[0051] The embodiment of the present application provides an electric device using a battery as a power source, and the electric 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 car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0052] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0053] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application. 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. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0054] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0055] Please refer to Figure 2 , Figure 2Schematic diagram of the exploded structure of the battery provided for some embodiments of the present application. The battery 100 includes a box 10 and a battery cell 20, and the battery cell 20 is contained in the box 10. Among them, the box 10 is used to provide a storage space for the battery cell 20, and the box 10 can adopt a variety of structures. In some embodiments, the box 10 may include a first part 11 and a second part 12, the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space for accommodating the battery cell 20. The second part 12 can be a hollow structure with one end open, the first part 11 can be a plate-like structure, and the first part 11 covers the open side of the second part 12, so that the first part 11 and the second part 12 jointly define a storage space; the first part 11 and the second part 12 can also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the box 10 formed by the first part 11 and the second part 12 can be in a variety of shapes, such as a cylinder, a cuboid, etc.

[0056] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.

[0057] Each battery cell 20 may be a secondary battery or a primary battery, or a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0058] Please refer to Figure 3 , Figure 3 The schematic diagram of the decomposition structure of a battery cell provided in some embodiments of the present application. A battery cell 20 refers to the smallest unit that constitutes a battery. Figure 3 The battery cell 20 includes an end cover 21, a shell 22, a battery cell assembly 23 and other functional components.

[0059] The end cap 21 refers to a component that covers the opening of the shell 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the shell 22 to match the shell 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 21 is not easily deformed when squeezed and collided, so that the battery cell 20 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals 21a can be provided on the end cap 21. The electrode terminal 21a can be used to electrically connect to the battery cell assembly 23 for outputting or inputting electrical energy of the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The material of the end cap 21 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating member may be provided inside the end cap 21, and the insulating member may be used to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be plastic, rubber, or the like.

[0060] The shell 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the battery cell assembly 23, electrolyte and other components. The shell 22 and the end cap 21 can be independent components, and an opening can be set on the shell 22, and the internal environment of the battery cell 20 is formed by covering the opening with the end cap 21 at the opening. Without limitation, the end cap 21 and the shell 22 can also be integrated. Specifically, the end cap 21 and the shell 22 can form a common connection surface before other components are put into the shell, and when the interior of the shell 22 needs to be encapsulated, the end cap 21 covers the shell 22. The shell 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 22 can be determined according to the specific shape and size of the battery cell assembly 23. The material of the shell 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0061] The battery cell assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more battery cell assemblies 23 may be contained in the housing 22. The battery cell assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the battery cell assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab 23a. The positive tab and the negative tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive active material and the negative active material react with the electrolyte, and the tab 23a connects the electrode terminals to form a current loop.

[0062] The present application embodiment provides a battery cell 20, Figure 4 This is a schematic structural diagram of the first pole piece 231 in some embodiments of the present application in an unfolded state. Figure 5 Schematic diagram of the structure of the battery cell 20 formed by folding in some embodiments of the present application, such as Figure 4 and Figure 5 As shown, the battery cell 20 includes a first pole piece 231, a diaphragm 233 and a plurality of second pole pieces 232. The first pole piece 231 is provided with a plurality of structurally weakened areas 234 extending along the width direction W of the first pole piece 231; the diaphragm 233 covers the opposite sides of the first pole piece 231; the plurality of second pole pieces 232 are alternately arranged on the diaphragm 233 on the opposite sides of the first pole piece 231, wherein, along the length direction L of the first pole piece 231, every two adjacent second pole pieces 232 are located on different sides of the first pole piece 231, and there is a corresponding structurally weakened area 234 between every two adjacent second pole pieces 232; wherein, the first pole piece 231 is folded at the plurality of structurally weakened areas 234, so that the first pole piece 231 and the plurality of second pole pieces 232 are alternately stacked on each other.

[0063] In the embodiment of the present application, the battery cell 20 can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., but the embodiment of the present application is not limited to this.

[0064] In the embodiment of the present application, the polarities of the first pole piece 231 and the second pole piece 232 are opposite, and the multiple segments of the first pole piece 231 and the second pole piece 232 are alternately stacked. Specifically, the first pole piece 231 can be a cathode pole piece, and the second pole piece 232 can be an anode pole piece; or, the first pole piece 231 can be an anode pole piece, and the second pole piece 232 can be a cathode pole piece.

[0065] Figure 4Schematic diagram of the structure of the first pole piece 231 in some embodiments of the present application in an unfolded state, L is the length direction of the first pole piece 231, and W is the width direction of the first pole piece 231. The first pole piece 231 is provided with a plurality of structurally weakened areas 234 extending along the width direction W of the first pole piece 231. The structurally weakened areas 234 can be provided by including a groove 235 on the first pole piece 231. The structurally weakened areas 234 can also be provided by including a through hole 236 on the first pole piece 231. The strength of the structurally weakened areas 234 is less than the mechanical strength of the remaining areas of the first pole piece 231. Exemplarily, the first pole piece 231 may include a current collector and an active material layer, the active material layer being provided on the surface of the current collector perpendicular to the thickness direction, and the active material layer being provided on both sides of the current collector. The structurally weakened areas 234 can be provided by removing the active material from the surface of the active material layer in a manner that weakens the mechanical strength of the first pole piece 231.

[0066] The first pole piece 231 is covered with a diaphragm 233 on two opposite sides, and the first pole piece 231 and the second pole piece 232 can be insulated by the diaphragm 233 to improve the working performance and safety of the battery cell 20. The present application has no particular restriction on the type of diaphragm 233, and any known porous structure diaphragm 233 with good chemical stability and mechanical stability can be selected. As an example, the main material of the diaphragm 233 can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride and ceramic. The diaphragm 233 can be a single-layer film or a multi-layer composite film without special restrictions. When the diaphragm 233 is a multi-layer composite film, the materials of each layer can be the same or different, without special restrictions.

[0067] Figure 5 The schematic diagram of the structure of the battery cell 20 formed by folding in some embodiments of the present application, the battery cell 20 includes a first pole piece 231, a diaphragm 233 and a plurality of second pole pieces 232. The first pole piece 231 and the diaphragm 233 covering the opposite sides of the first pole piece 231 are folded at a plurality of structurally weakened areas 234, so that a plurality of segments of the first pole piece 231 and a plurality of second pole pieces 232 are alternately stacked with each other, the structurally weakened areas 234 are located at the bend, the segments of every two adjacent first pole pieces 231 are connected by the structurally weakened areas 234, every two adjacent second pole pieces 232 are located on different sides of the first pole piece 231, and there is a corresponding structurally weakened area 234 between every two adjacent second pole pieces 232.

[0068] In the structural weakened area 234 where the continuous electrode sheet is folded, the first electrode sheet 231 of the structural weakened area 234 wraps the second electrode sheet 232, and the first electrode sheet 231 overlaps with the second electrode sheet 232, so that during the reaction of the battery cell 20, the lithium ions electrolyzed by the cathode electrode sheet can all reach the coating area of ​​the anode electrode sheet active material of the anode electrode sheet directly opposite to it, and the active material at the folded position is not easy to fall off due to folding, and the first electrode sheet 231 is not easy to break due to folding.

[0069] In the embodiment of the present application, a plurality of structural weakened areas 234 extending along the width direction W of the first pole piece 231 are provided on the first pole piece 231. Since the mechanical strength of the plurality of structural weakened areas 234 is less than the mechanical strength of the remaining areas of the first pole piece 231, by providing the plurality of structural weakened areas 234 extending along the width direction W of the first pole piece 231 on the first pole piece 231, the first pole piece 231 can be made easier to bend and can be accurately folded at a predetermined position, thereby reducing the misalignment between the first pole piece 231 and the second pole piece 232 and improving the flatness of the first pole piece 231 after folding. Furthermore, when multiple segments of the first pole piece 231 and multiple second pole pieces 232 are alternately stacked on each other, every two adjacent segments of the first pole piece 231 are connected by a structural weakened area 234, every two adjacent second pole pieces 232 are located on different sides of the first pole piece 231, and there is a corresponding structural weakened area 234 between every two adjacent second pole pieces 232, thereby reducing the gap between the first pole piece 231 and the second pole piece 232, reducing the lithium plating problem of the battery cell 20, and thus improving the performance of the battery cell 20.

[0070] According to some embodiments of the present application, the structural weakened area 234 includes a groove 235 extending along the width direction W of the first pole piece 231 .

[0071] In the embodiment of the present application, the groove 235 extends along the width direction W of the first pole piece 231, and the groove 235 can be formed by a metal tool, a laser tool, liquid etching, etc. The cross-section of the groove 235 can be set to a rectangle, a trapezoid, or a triangle, etc. Exemplarily, the first pole piece 231 may include a current collector and an active material layer, and the active material layer is arranged on the current collector. The groove 235 extending along the width direction W of the first pole piece 231 can be formed by removing the active material of the active material layer, and the depth of the groove 235 does not exceed the thickness of the first pole piece 231.

[0072] Optionally, Figure 6 for Figure 4In the AA cross-sectional view in FIG. 2 , the cross-section of the groove 235 may be triangular, and the number of the grooves 235 may be multiple. After the first pole piece 231 is folded at the structural weakened area 234, the groove 235 is located inside the bend. When the groove 235 is located inside the bend, even if the radius of curvature inside the bend is small, or the width of the groove 235 along the extension direction is small, it is not easy for two adjacent segments of the first pole piece 231 to interfere with each other, so that the first pole piece 231 can be folded smoothly and the possibility of powder falling is reduced.

[0073] In the embodiment of the present application, the structural weakened area 234 includes a groove 235 extending along the width direction W of the first pole piece 231, which has a better effect of guiding the first pole piece 231 to bend, and the groove 235 can improve the accuracy of the folding position and reduce the misalignment of two adjacent layers of pole pieces in the battery cell 20 after stacking, so that the battery cell 20 has good performance.

[0074] According to some embodiments of the present application, the structural weakened area 234 includes two grooves 235 extending along the width direction W of the first pole piece 231 , and the two grooves 235 are spaced apart from each other along the length direction L of the first pole piece 231 .

[0075] In the embodiment of the present application, the structural weakened area 234 includes two grooves 235 extending along the width direction W of the first pole piece 231. The two grooves 235 are spaced apart from each other along the length direction L of the first pole piece 231, so that the first pole piece 231 can be folded along the two grooves 235, making the first pole piece 231 easier to fold, improving the accuracy of the folding position, and making the segments of the first pole piece 231 aligned with each other, reducing the misalignment between the first pole piece 231 and the second pole piece 232, thereby further improving the performance of the battery cell 20.

[0076] According to some embodiments of the present application, the distance between the two grooves 235 is greater than or equal to the thickness of the corresponding second pole piece 232 .

[0077] In the embodiment of the present application, the spacing between the two grooves 235 is greater than or equal to the thickness of the corresponding second pole piece 232. The spacing between the structurally weakened areas 234 of the first pole piece 231 along the length direction L of the first pole piece 231 can be greater than or equal to the thickness of the corresponding second pole piece 232. The first pole piece 231 is folded at a plurality of structurally weakened areas 234, and the spacing at the formed bending is greater than or equal to the thickness of the second pole piece 232, so that when the plurality of segments of the first pole piece 231 and the plurality of second pole pieces 232 are alternately stacked, the second pole piece 232 will not be squeezed by the first pole piece 231, and the gap between the first pole piece 231 and the second pole piece 232 at the bending can be reduced, thereby reducing the lithium deposition problem of the battery cell 20, thereby improving the performance of the battery cell 20.

[0078] According to some embodiments of the present application, the length of each groove 235 is less than or equal to the width of the first pole piece 231 .

[0079] In the embodiment of the present application, the length of each groove 235 is less than or equal to the width of the first pole piece 231, which limits the maximum length of the groove 235. Since the length of the groove 235 does not exceed the width of the first pole piece 231, the mechanical strength of the structural weakened area 234 can be maintained at a certain level, thereby reducing the probability of the first pole piece 231 breaking during the folding process, thereby improving the production yield of the battery cell 20.

[0080] According to some embodiments of the present application, the structural weakened area 234 further includes a through hole 236 penetrating the thickness of the first pole piece 231 .

[0081] In the embodiment of the present application, the through hole 236 can be a circular hole, a rectangular hole, an elliptical hole or a diamond hole, etc. By providing the through hole 236, the strength of the bend can also be weakened, playing the same role as the groove 235. At the same time, the through hole 236 can also play a positioning role. The number of the through hole 236 can be one or more.

[0082] For example, Figure 4 As shown, the through hole 236 may be located in the middle of the two grooves 235 .

[0083] In some embodiments, the structural weakened zone 234 of the first pole piece 231 may include a groove 235 and a through hole 236 at the same time. The groove 235 and the through hole 236 may jointly weaken the mechanical strength of the structural weakened zone 234 of the first pole piece 231. Since the structural weakened zone 234 of the first pole piece 231 includes the through hole 236, when the same mechanical strength needs to be achieved, the depth of the groove 235 may be appropriately reduced, which is beneficial to improving the stress condition of the first pole piece 231 in the structural weakened zone 234 when folding, thereby reducing the risk of breakage while ensuring that the first pole piece 231 is easy to bend.

[0084] In the embodiment of the present application, since the thickness of the first pole piece 231 is relatively thin, the through hole 236 does not need to be precisely controlled in depth, which can reduce the requirements for processing accuracy. In addition, the through hole 236 can greatly weaken the strength of the first pole piece 231, making it easy to fold.

[0085] According to some embodiments of the present application, the number N of the through holes 236 satisfies: N≥2.

[0086] In the embodiment of the present application, the through holes 236 may be arranged at intervals along the width direction W of the first pole piece 231. By providing a plurality of through holes 236, the mechanical strength of the first pole piece 231 can be weakened, and the structural weakened area 234 of the first pole piece 231 can maintain a certain mechanical strength, so as to reduce the possibility of the first pole piece 231 breaking when being folded.

[0087] According to some embodiments of the present application, a plurality of structural weakened areas 234 are equidistantly spaced from each other along the length direction L of the first pole piece 231 .

[0088] In the embodiment of the present application, Figure 4 In the structural schematic diagram of the first pole piece 231 in the unfolded state, a plurality of structural weakened areas 234 are arranged at intervals along the length direction L of the first pole piece 231, and each structural weakened area 234 is located at the position to be folded. The plurality of structural weakened areas 234 are equidistantly spaced from each other along the length direction L of the first pole piece 231, and the plurality of structural weakened areas 234 have high parallelism, and the edges of the folded battery cell 20 along the stacking direction are neat, and the folding can be assisted by an automatic flapping mechanism during the folding process, so as to facilitate folding in place.

[0089] In the embodiment of the present application, multiple structural weakened areas 234 are equidistantly spaced from each other along the length direction L of the first pole piece 231. The structural weakened areas 234 can be located at the bend by setting a suitable spacing distance to weaken the strength of the bend, making the first pole piece 231 easier to bend and accurately folded at a predetermined position, thereby reducing the misalignment of the multi-layer pole pieces and improving the flatness of the first pole piece 231 after folding, thereby improving the performance of the battery cell 20.

[0090] According to some embodiments of the present application, the first pole piece 231 is an anode pole piece, and the second pole piece 232 is a cathode pole piece.

[0091] In the embodiment of the present application, after the first pole piece 231 is folded, it is located on the outermost side in the stacking direction. Generally, the material of the cathode active substance in the cathode pole piece is a ternary material, lithium manganese oxide or lithium iron phosphate, etc., and the material of the anode active substance in the anode pole piece is generally graphite or silicon. Since the material of the cathode active substance is more expensive than the material of the anode active substance, the outermost layer of the battery cell 20 is set as the anode pole piece, which can reduce the number of layers of the negative pole piece after folding and enable the cathode active substance of the cathode pole piece to be fully utilized.

[0092] According to some embodiments of the present application, a method for producing a battery monomer is provided. Figure 7 A flowchart of a method for producing a battery cell provided in some embodiments of the present application. Figure 7 , the method comprising:

[0093] Step S710: forming a plurality of structural weakened areas on the first pole piece, wherein the plurality of structural weakened areas extend along a width direction of the first pole piece.

[0094] Step S720: Covering the surfaces of two opposite sides of the first pole piece with a diaphragm.

[0095] Step S730: Alternately arrange a plurality of second pole pieces on the diaphragm on opposite sides of the first pole piece, wherein along the length direction of the first pole piece, every two adjacent second pole pieces are located on different sides of the first pole piece, and there is a corresponding structural weakened area between every two adjacent second pole pieces.

[0096] Step S740: folding the first pole sheet at a plurality of structural weakened areas so that the first pole sheet and a plurality of second pole sheets are alternately stacked on each other.

[0097] In the embodiment of the present application, in the embodiment of the present application, the battery cell 20 can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., but the embodiment of the present application is not limited to this.

[0098] In the embodiment of the present application, the polarities of the first pole piece 231 and the second pole piece 232 are opposite, and the multiple segments of the first pole piece 231 and the second pole piece 232 are alternately stacked. Specifically, the first pole piece 231 can be a cathode pole piece, and the second pole piece 232 can be an anode pole piece; or, the first pole piece 231 can be an anode pole piece, and the second pole piece 232 can be a cathode pole piece.

[0099] In the embodiment of the present application, a plurality of structurally weakened areas 234 extending along the width direction W of the first pole piece 231 are formed on the first pole piece 231. The structurally weakened areas 234 can be formed by providing a groove 235 on the first pole piece 231. The structurally weakened areas 234 can also be formed by providing a through hole 236 on the first pole piece 231. The strength of the structurally weakened areas 234 is less than the mechanical strength of the remaining areas of the first pole piece 231. Exemplarily, the first pole piece 231 may include a current collector and an active material layer. The active material layer is provided on the surface of the current collector perpendicular to the thickness direction. The active material layer can be provided on both sides of the current collector. The structurally weakened areas 234 can be formed by removing the active material from the surface of the active material layer to weaken the mechanical strength of the first pole piece 231.

[0100] In the embodiment of the present application, before forming the battery cell 20, the first pole piece 231 and the two diaphragms 233 are stacked and arranged, and after compounding, a continuous composite pole piece that can be bent is formed, and the first pole piece 231 and the diaphragm 233 are alternately arranged, and the diaphragm 233 is provided on both sides of the first pole piece 231 to play an insulating role. Adhesive layers can be provided on both sides of the diaphragm 233, for example, the adhesive layer is a PCS layer (Polyvinylidene fluoride coated separator). In the process of heating and compounding and applying pressure to the first pole piece 231 and the diaphragm 233, many particles in the PCS layer distributed in a point shape are flattened to generate adhesion to the first pole piece 231.

[0101] In one process, Figure 8 FIG. 2 is a composite diagram of the first pole piece 231 and the diaphragm 233 in some embodiments of the present application. Figure 8 As shown, the surfaces of the two opposite sides of the first pole piece 231 are covered with a diaphragm 233 , and pressure is applied by a roller 237 to attach the diaphragm 233 to the first pole piece 231 through the PCS layer. Fig. 9 FIG. 2 is a composite schematic diagram of the first pole piece 231, the second pole piece 232 and the diaphragm 233 in some embodiments of the present application. Fig. 9 As shown, along the length direction L of the first pole piece 231, a plurality of second pole pieces 232 are alternately arranged on the diaphragm 233 on opposite sides of the first pole piece 231, and every two adjacent second pole pieces 232 are located on different sides of the first pole piece 231, and there is a corresponding structural weakened area 234 between every two adjacent second pole pieces 232, and pressure is applied by a roller 237 to attach the second pole piece 232 to the diaphragm 233.

[0102] In addition, it can also be compounded by cold pressing, electrophoresis or bonding.

[0103] In an embodiment of the present application, the first pole piece 231 and the diaphragm 233 covering the opposite sides of the first pole piece 231 are folded in multiple structural weakened areas 234, so that multiple segments of the first pole piece 231 and multiple second pole pieces 232 are stacked alternately with each other, the structural weakened areas 234 are located at the bends, and every two adjacent segments of the first pole pieces 231 are connected by the structural weakened areas 234, and every two adjacent second pole pieces 232 are located on different sides of the first pole piece 231, and there is a corresponding structural weakened area 234 between every two adjacent second pole pieces 232.

[0104] In the structural weakened area 234 where the continuous electrode sheet is folded, the first electrode sheet 231 of the structural weakened area 234 wraps the second electrode sheet 232, and the first electrode sheet 231 overlaps with the second electrode sheet 232, so that during the reaction of the battery cell 20, the lithium ions electrolyzed by the cathode electrode sheet can all reach the coating area of ​​the anode electrode sheet active material of the anode electrode sheet directly opposite to it, and the active material at the folded position is not easy to fall off due to folding, and the first electrode sheet 231 is not easy to break due to folding.

[0105] In the embodiment of the present application, by forming a plurality of structural weakened areas 234 extending along the width direction W of the first pole piece 231 on the first pole piece 231, the first pole piece 231 can be bent more easily and accurately folded at a predetermined position, thereby reducing the misalignment between the first pole piece 231 and the second pole piece 232 and improving the flatness of the first pole piece 231 after folding. In addition, when the plurality of segments of the first pole piece 231 and the plurality of second pole pieces 232 are alternately stacked with each other, the segments of each two adjacent first pole pieces 231 are connected by the structural weakened area 234, each two adjacent second pole pieces 232 are located on different sides of the first pole piece 231, and there is a corresponding structural weakened area 234 between each two adjacent second pole pieces 232, thereby reducing the gap between the first pole piece 231 and the second pole piece 232, reducing the problem of lithium deposition, and thus improving the performance of the battery cell 20.

[0106] The embodiment of the present application provides a battery including a battery cell 20 in any implementation manner.

[0107] In the embodiments of the present application, the battery can be applied to but not limited to mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, the electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc., and the spacecraft can include airplanes, rockets, space shuttles and spacecrafts, etc.

[0108] By adopting the battery cell 20 in the embodiment of the present application, the battery reliability can be improved.

[0109] An embodiment of the present application further provides an electrical device, which includes a battery in any embodiment, and the battery is used to provide electrical energy.

[0110] In the embodiments of the present application, 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 car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0111] By adopting the battery in the embodiment of the present application, the reliability of the electrical device is improved.

[0112] The technical solution of the present application is further described below by means of a specific embodiment. Figures 1 to 9 As shown,

[0113] The battery cell 20 includes a first pole piece 231, a diaphragm 233 and a plurality of second pole pieces 232. The first pole piece 231 is provided with a plurality of structurally weakened areas 234 extending along the width direction W of the first pole piece 231; the diaphragm 233 covers the opposite sides of the first pole piece 231; the plurality of second pole pieces 232 are alternately arranged on the diaphragm 233 on the opposite sides of the first pole piece 231, wherein along the length direction L of the first pole piece 231, every two adjacent second pole pieces 232 are located on different sides of the first pole piece 231, and there is a corresponding structurally weakened area 234 between every two adjacent second pole pieces 232; wherein the first pole piece 231 is folded at the plurality of structurally weakened areas 234, so that the first pole piece 231 and the plurality of second pole pieces 232 are alternately stacked on each other. The first pole piece 231 is an anode pole piece, and the second pole piece 232 is a cathode pole piece.

[0114] The structural weakened area 234 includes two grooves 235 extending along the width direction W of the first pole piece 231, and the two grooves 235 are spaced apart from each other along the length direction L of the first pole piece 231. The spacing between the two grooves 235 is greater than or equal to the thickness of the corresponding second pole piece 232. The length of each groove 235 is less than or equal to the width of the first pole piece 231.

[0115] The structural weakened area 234 further includes a through hole 236 penetrating the thickness of the first pole piece 231. The number N of the through holes 236 satisfies: N≥2.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell (20), characterized in that: include: A first pole piece (231), wherein the first pole piece (231) is provided with a plurality of structural weakened areas (234) extending along a width direction of the first pole piece (231); a diaphragm (233), the diaphragm (233) covering surfaces on two opposite sides of the first pole piece (231); and a plurality of second pole pieces (232), the plurality of second pole pieces (232) being alternately arranged on the diaphragm (233) on opposite sides of the first pole piece (231), wherein, along the length direction of the first pole piece (231), every two adjacent second pole pieces (232) are located on different sides of the first pole piece (231), and a corresponding structural weakened area (234) exists between every two adjacent second pole pieces (232); The first pole piece (231) is folded at the plurality of structural weakened areas (234), so that the first pole piece (231) and the plurality of second pole pieces (232) are stacked alternately with each other.

2. The battery cell (20) according to claim 1, characterized in that: The structural weakened area (234) comprises a groove (235) extending along the width direction of the first pole piece (231).

3. The battery cell (20) according to claim 1 or 2, characterized in that: The structural weakened area (234) comprises two grooves (235) extending along the width direction of the first pole piece (231), and the two grooves (235) are spaced apart from each other along the length direction of the first pole piece (231).

4. The battery cell (20) according to claim 3, characterized in that: The distance between the two grooves (235) is greater than or equal to the thickness of the corresponding second pole piece (232).

5. The battery cell (20) according to any one of claims 2 to 4, characterized in that: The length of each groove (235) is less than or equal to the width of the first pole piece (231).

6. The battery cell (20) according to any one of claims 1 to 5, characterized in that: The structurally weakened area (234) further comprises a through hole (236) penetrating the thickness of the first pole piece (231).

7. The battery cell (20) according to claim 6, characterized in that: The number N of the through holes (236) satisfies: N≥2.

8. The battery cell 20 according to any one of claims 1 to 7, characterized in that: The plurality of structural weakened areas (234) are equidistantly spaced from one another along the length direction of the first pole piece (231).

9. The battery cell 20 according to any one of claims 1 to 8, characterized in that: The first pole piece (231) is an anode pole piece, and the second pole piece (232) is a cathode pole piece.

10. A method for producing a battery cell, characterized in that: The method comprises: forming a plurality of structural weakened areas on the first pole piece, wherein the plurality of structural weakened areas extend along a width direction of the first pole piece; Covering the surfaces of the first pole piece on two opposite sides with a diaphragm; Alternately arranging a plurality of second pole pieces on the diaphragms on opposite sides of the first pole piece, wherein along the length direction of the first pole piece, every two adjacent second pole pieces are located on different sides of the first pole piece, and there is a corresponding structural weakened area between every two adjacent second pole pieces; The first pole sheet is folded at the plurality of structural weakened areas so that the first pole sheet and the plurality of second pole sheets are alternately stacked on each other.

11. A battery, characterized in that: The invention comprises a battery cell (20) as claimed in any one of claims 1 to 10.

12. An electrical device, characterized in that: The electrical device comprises the battery as claimed in claim 11, wherein the battery is used to provide electrical energy.

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