Battery assembly and processing method and device, battery cell, battery and electrical equipment

Abstract

The present application provides an electrode assembly and a processing method and device, a battery cell, a battery and an electrical device. The electrode assembly includes: a cathode electrode sheet, an anode electrode sheet, a separator and a conductive layer, the separator is used to separate the cathode electrode sheet and the anode electrode sheet; the cathode electrode sheet, the separator and the anode electrode sheet are wound to form a bending area; the conductive layer is configured so that at least a portion of the conductive layer is arranged on the surface of the cathode electrode sheet in the bending area, the cathode electrode sheet includes a covered area covered by the conductive layer, and the conductive layer is connected in parallel with the covered area. According to the technical solution described above, the conductive layer can maintain the electrical connection between the broken cathode electrode sheets, suppress the increase in the internal resistance of the electrode assembly, and thereby reduce the capacity attenuation of the battery cell and maintain the stability of the capacity of the battery cell.

Description

Technical Field

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

[0002] Rechargeable batteries, also known as secondary batteries, are batteries that can be recharged after discharge to reactivate the active materials and continue to be used. Rechargeable batteries are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and power tools.

[0003] Rechargeable batteries may include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and secondary alkaline zinc-manganese batteries, among others.

[0004] At present, the batteries most commonly used in automobiles are lithium-ion batteries. As a rechargeable battery, lithium-ion batteries have the advantages of small size, high energy density, high power density, many cycles and long storage time.

[0005] Rechargeable batteries include an electrode assembly and an electrolyte. The electrode assembly includes a cathode electrode sheet, an anode electrode sheet, and a separator located between the cathode and anode electrodes. Each cathode electrode sheet has a cathode active material layer, such as lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate, or lithium nickel cobalt manganese oxide. Each anode electrode sheet has an anode active material layer, such as graphite or silicon.

[0006] As the application scope of rechargeable batteries continues to expand, users have increasingly higher requirements for the stability of the battery capacity of rechargeable battery cells.

[0007] How to maintain the stability of the charging capacity of battery cells has become a difficult problem in the industry. Summary of the Invention

[0008] Various aspects of the present application provide an electrode assembly and a processing method and apparatus, a battery cell, a battery, and an electrical device, which overcome the above-mentioned problems or at least partially solve the above-mentioned problems.

[0009] The first aspect of the present application provides an electrode assembly, including a cathode electrode sheet, an anode electrode sheet, an isolating member and a conductive layer, wherein the isolating member is used to isolate the cathode electrode sheet and the anode electrode sheet; the cathode electrode sheet, the isolating member and the anode electrode sheet are wound to form a bending area; the conductive layer is configured so that at least a portion of the conductive layer is arranged on the surface of the cathode electrode sheet in the bending area, the cathode electrode sheet includes a covered area covered by the conductive layer, and the conductive layer is connected in parallel to the covered area.

[0010] By providing a conductive layer on the surface of the cathode electrode sheet in the bend region and connecting it in parallel with the covered area of ​​the cathode electrode sheet, if the covered area of ​​the cathode electrode sheet in the bend region breaks, causing the internal resistance of the electrode assembly to increase, the conductive layer can maintain the electrical connection between the broken cathode electrode sheets, suppressing the increase in the internal resistance of the electrode assembly, thereby reducing the capacity decay of the battery cells and maintaining the stability of the battery cell capacity. In addition, the conductive layer can also provide reinforcement for the cathode electrode sheet in the bend region, reducing the chance of the covered area of ​​the cathode electrode sheet breaking.

[0011] In some embodiments, a conductive layer is provided on one or both surfaces of the cathode electrode.

[0012] In this embodiment, by providing a conductive layer on one or both surfaces of the cathode electrode sheet, the occurrence of breakage in the covered area of ​​the cathode electrode sheet in the bending region, which may lead to an increase in the internal resistance of the electrode assembly, can be effectively suppressed, and the cathode electrode sheet in the bending region can be reinforced to reduce the occurrence of breakage in the covered area of ​​the cathode electrode sheet.

[0013] In some embodiments, at least a portion of the conductive layer is disposed at the first bending portion and / or the second bending portion of the cathode electrode in the bending region.

[0014] In this embodiment, a conductive layer is provided at the first and second bending parts of the cathode electrode in the bending area. The conductive layer can also strengthen the first and second bending parts of the cathode electrode, thereby reducing the occurrence of breakage in the covered area of ​​the cathode electrode and increasing the internal resistance of the electrode assembly, thereby improving the capacity stability of the battery cell.

[0015] In some embodiments, the conductive layer is further disposed at the first bending portion of the anode electrode sheet and / or the second bending portion of the anode electrode sheet in the bending region, and is connected in parallel with the anode electrode sheet.

[0016] In this embodiment, a conductive layer is provided at the first and second bending parts of the anode electrode in the bending area. The conductive layer can also strengthen the first and second bending parts of the anode electrode, thereby reducing the possibility of the anode active material layer breaking or falling off due to bending of the anode electrode, or the occurrence of the anode electrode breaking.

[0017] In some embodiments, the conductive layer includes a conductive base layer, and in the bending region, the conductive base layer is connected in parallel with the cathode electrode.

[0018] In this embodiment, the conductive layer includes a conductive base layer, which strengthens the cathode electrode to reduce the occurrence of breakage in the covered area of ​​the cathode electrode and the increase in the internal resistance of the electrode assembly, thereby improving the capacity stability of the battery cell.

[0019] In some embodiments, in the bending region, the entire surface of the conductive base layer adjacent to the cathode electrode is electrically connected to the covered region, and along the winding direction of the electrode assembly, the center line of the bending region passes through the conductive base layer.

[0020] In this embodiment, the bending angle of the cathode electrode at the center line of the bending area is large, and the possibility of breakage is greater; along the winding direction of the electrode assembly, the center line of the bending area passes through the conductive base layer. When the cathode electrode breaks near the center line, the conductive base layer can cover the part of the covered area of ​​the cathode electrode where the break occurs. Since the entire surface of the conductive base layer adjacent to the cathode electrode is electrically connected to the cathode electrode, the two parts of the covered area of ​​the cathode electrode where the break occurs can still be electrically connected through the conductive base layer, thereby suppressing the increase in the internal resistance of the electrode assembly.

[0021] In some embodiments, the conductive layer further includes an ion blocking layer, which is disposed on the side of the conductive base layer away from the cathode electrode and covers the conductive base layer. The ion blocking layer is used to block at least some ions from escaping from the cathode electrode located on the side of the ion blocking layer.

[0022] In this embodiment, by providing an ion blocking layer, during charging, at least a portion of ions can be blocked from escaping from the cathode electrode on one side of the ion blocking layer and embedding into the anode electrode, thereby reducing the occurrence of lithium deposition in the anode electrode in the bent area.

[0023] In some embodiments, in the bending region, along the winding direction of the electrode assembly, the conductive base layer includes two ends located on both sides of a center line of the bending region, and the two ends are electrically connected to the covered region respectively.

[0024] In this embodiment, the bending angle of the cathode electrode sheet at the center line of the bending area is large, and the possibility of breakage is greater; along the winding direction of the electrode assembly, the center line of the bending area passes through the conductive base layer. When the cathode electrode sheet breaks near the center line, the conductive base layer can cover the part of the covered area of ​​the cathode electrode sheet where the break occurs. Since the two ends of the conductive base layer on both sides of the center line of the bending area are electrically connected to the cathode electrode sheet respectively, the two parts of the covered area of ​​the cathode electrode sheet where the break occurs can still be electrically connected through the conductive base layer, thereby suppressing the increase in the internal resistance of the electrode assembly.

[0025] In some embodiments, the conductive base layer also includes a main body portion, which is connected to the two ends; the conductive layer also includes an ion blocking layer, which is arranged between the main body portion of the conductive base layer and the cathode electrode, and the ion blocking layer is used to block at least a part of the ions from escaping from the cathode electrode located on one side of the ion blocking layer.

[0026] In this embodiment, an ion blocking layer is arranged between the main body of the conductive base layer and the cathode electrode. The ion blocking layer is attached to the surface of the cathode electrode, which can better block a part of the ions from escaping from the cathode electrode located on one side of the ion blocking layer and embedding into the anode electrode, thereby reducing the occurrence of lithium deposition on the anode electrode in the bending area.

[0027] In some embodiments, the conductive layer further includes an insulating layer, which is disposed on a side of the conductive base layer away from the cathode electrode and covers the conductive base layer.

[0028] In this embodiment, an insulating layer is provided on the side of the conductive base layer away from the cathode electrode, and the insulating layer covers the conductive base layer. When the isolation piece in the bending area is broken, the insulating layer can prevent the conductive base layer from directly contacting the anode electrode and causing a short circuit between the cathode electrode and the anode electrode.

[0029] In some embodiments, there are multiple conductive base layers, and the multiple conductive base layers are arranged at intervals along a direction parallel to the winding axis of the electrode assembly.

[0030] In this embodiment, a plurality of conductive base layers are provided and arranged at intervals. Compared with an integrated conductive base layer, the space occupied by the conductive base layer can be reduced, thereby improving the energy density of the battery cell.

[0031] In some embodiments, the total flow area of ​​the conductive base layer is greater than or equal to 1 / 3 of the flow area of ​​the current collector of the connected cathode electrode.

[0032] In this embodiment, the total flow area of ​​the conductive base layer must be greater than or equal to 1 / 3 of the flow area of ​​the cathode electrode collector to avoid the conductive base layer temperature rising due to the small flow area of ​​the conductive base layer and falling off from the cathode electrode, thereby ensuring safe use.

[0033] In some embodiments, the material of the ion blocking layer comprises magnesium oxide, calcium oxide, boehmite, wollastonite, barium sulfate, calcium sulfate, calcium carbonate, aluminum oxide, silicon dioxide, polyethylene, polyvinyl chloride, polyacrylic acid / acrylate, styrene-butadiene, styrene-acrylic acid, ethylene-vinyl acetate copolymer, polypropylene, polyvinylidene fluoride, carboxymethyl cellulose, epoxy glue, organic silica gel, polyurethane glue, styrene-isoprene-styrene copolymer glue and at least one of the modifications of the above substances.

[0034] In some embodiments, the material of the conductive base layer includes at least one of silver, gold, nickel, copper, aluminum, polypyrrole, polyphenylene sulfide, polyphthalocyanine, polyaniline, and polythiophene.

[0035] The second aspect of the present application provides a battery cell, which includes: a shell, an electrolyte, a cover plate and at least one electrode assembly of the above-mentioned embodiment, wherein the shell has a accommodating cavity and an opening, and the electrode assembly and the electrolyte are accommodated in the accommodating cavity; the cover plate is used to close the opening of the shell.

[0036] A third aspect of the present application provides a battery, comprising a box and at least one battery cell according to the above embodiment, wherein the battery cell is housed in the box.

[0037] A fourth aspect of the present application provides an electric device, wherein an electric device is configured to receive electric power provided by the battery of the above embodiment.

[0038] The fifth aspect of the present application provides a processing method for an electrode assembly, including providing a cathode electrode sheet, an anode electrode sheet, and an isolating member; providing a conductive layer, and arranging the conductive layer at a preset position of the cathode electrode sheet, the cathode electrode sheet including a covered area covered by the conductive layer, so that the conductive layer and the covered area are connected in parallel; winding the cathode electrode sheet, the anode electrode sheet, and the isolating member, the cathode electrode sheet, the isolating member, and the anode electrode sheet form a bending area through winding, and the preset position is configured so that at least a portion of the conductive layer is located in the bending area after winding.

[0039] The sixth aspect of the present application provides a processing device for an electrode assembly, including a providing device for providing a cathode electrode sheet, an anode electrode sheet, an isolating member and a conductive layer; a connecting device for connecting the conductive layer to the cathode electrode sheet at a preset position of the cathode electrode sheet, the cathode electrode sheet includes a covered area covered by the conductive layer, and the connecting device is used to connect the conductive layer and the covered area in parallel; a winding device for winding the cathode electrode sheet, the anode electrode sheet and the isolating member, the cathode electrode sheet, the isolating member and the anode electrode sheet are wound to form a bending area, and the preset position is configured so that at least a portion of the conductive layer is located in the bending area after winding.

[0040] The above description is only an overview of the technical solutions of the embodiments of the present application. In order to more clearly understand the technical means of the embodiments of the present application, they 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 embodiments 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

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0042] Figure 1 A schematic diagram of the three-dimensional structure of an electrode assembly in the prior art;

[0043] Figure 2 for Figure 1 A schematic structural diagram of a cross section of an electrode assembly along a direction perpendicular to the winding axis Z;

[0044] Figure 3 for Figure 1 A schematic diagram of resistance change of an electrode assembly after a covered area of ​​a cathode electrode piece is broken;

[0045] Figure 4 This is a schematic structural diagram of a cross-section of a flat electrode assembly perpendicular to the winding axis according to one embodiment of the present application;

[0046] Figure 5 This is a schematic structural diagram of an anode electrode sheet according to another embodiment of the present application;

[0047] Figure 6 This is a schematic structural diagram of a cross section perpendicular to the winding axis of another flat electrode assembly according to another embodiment of the present application;

[0048] Figure 7 This is a schematic structural diagram of a cross section perpendicular to the winding axis of another flat electrode assembly according to another embodiment of the present application;

[0049] Figure 8 This is a schematic structural diagram of a cross section perpendicular to the winding axis of another flat electrode assembly according to another embodiment of the present application;

[0050] Figure 9 This is a schematic structural diagram of a cross section perpendicular to the winding axis of another flat electrode assembly according to another embodiment of the present application;

[0051] Figure 10 This is a partially enlarged structural schematic diagram of a cross section perpendicular to the winding axis of another flat electrode assembly according to another embodiment of the present application;

[0052] Figure 11 This is a schematic structural diagram of a cross section perpendicular to the winding axis of another flat electrode assembly according to another embodiment of the present application;

[0053] Figure 12 For this application Figure 5 A schematic diagram of the EE cross-sectional structure of an embodiment;

[0054] Figure 13 For this application Figure 5 EE cross-sectional structural diagram of another embodiment;

[0055] Figure 14 For this application Figure 13 An exploded schematic diagram of a conductive film according to an embodiment of the present invention;

[0056] Figure 15 For this application Figure 13 An exploded schematic diagram of a conductive film according to another embodiment of the present invention;

[0057] Figure 16 For this application Figure 15 Schematic diagram of the combined state of the conductive film;

[0058] Figure 17 For this application Figure 5 EE cross-sectional structural diagram of another embodiment;

[0059] Figure 18 For this application Figure 17 An exploded schematic diagram of a conductive film according to an embodiment of the present invention;

[0060] Figure 19 For this application Figure 17 An exploded schematic diagram of a conductive film according to another embodiment of the present invention;

[0061] Figure 20 For this application Figure 5 EE cross-sectional structural diagram of another embodiment;

[0062] Figure 21 For this application Figure 20 An exploded schematic diagram of a conductive film according to an embodiment of the present invention;

[0063] Figure 22 for Figure 4 A schematic diagram of the cross-sectional structure of an embodiment in the M1 direction;

[0064] Figure 23 for Figure 4 A schematic cross-sectional structure diagram of another embodiment in the M1 direction;

[0065] Figure 24 This is a schematic structural diagram of a battery cell according to another embodiment of the present application;

[0066] Figure 25 This is a schematic structural diagram of a battery module according to another embodiment of the present application;

[0067] Figure 26 This is a schematic structural diagram of a battery according to another embodiment of the present application;

[0068] Figure 27 This is a schematic structural diagram of an electrical device according to another embodiment of the present application;

[0069] Figure 28 A schematic flow chart of a method for processing an electrode assembly according to another embodiment of the present application;

[0070] Figure 29 This is a structural schematic diagram of a processing device for an electrode assembly according to another embodiment of the present application. DETAILED DESCRIPTION

[0071] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0073] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0074] The term "and / or" in this document simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0075] In the description of the present application, it should be understood that the 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., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do 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 present application. In addition, the terms "first", "second", etc. in the specification and claims of the present application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order, and may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, "multiple" means two or more.

[0076] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0077] In order to make lithium-ion batteries smaller and have higher energy density, the cathode electrode sheet, anode electrode sheet and separator in the electrode assembly of the lithium-ion battery can be wound and then compacted. Figure 1 As shown, it is a schematic diagram of the three-dimensional structure of an electrode assembly 10, which includes an anode electrode sheet, a cathode electrode sheet and a separator, wherein the anode electrode sheet, the cathode electrode sheet and the separator are stacked and wound around the winding axis Z to form a winding structure, and the separator is an insulating film of the prior art, which is used to separate the anode electrode sheet and the cathode electrode sheet to prevent the anode electrode sheet and the cathode electrode sheet from short-circuiting. The winding structure of the electrode assembly is a flat body shape, and the schematic diagram of the structure of the cross section of the electrode assembly along the direction perpendicular to the winding axis Z can be as shown below. Figure 2 shown.

[0078] Combine Figure 1 and Figure 2The electrode assembly 10 includes a straight region C and a bent region B located at both ends of the straight region C. The straight region C refers to a region having a parallel structure in the wound structure, that is, the anode electrode sheet 12, the cathode electrode sheet 11 and the separator 13 in the straight region C are substantially parallel to each other, that is, the surface of each layer of the anode electrode sheet 12, the cathode electrode sheet 11 and the separator 13 of the electrode assembly 10 in the straight region C is a plane. The bent region B refers to a region having a bent structure in the wound structure, that is, the anode electrode sheet 12, the cathode electrode sheet 11 and the separator 13 in the bent region B are all bent, that is, the surface of each layer of the anode electrode sheet 12, the cathode electrode sheet 11 and the separator 13 of the electrode assembly 10 in the bent region B is a curved surface, and the bent region B has a bending direction A. The bending direction A can be understood as a direction from the surface of the electrode assembly along the bending region to the straight region, for example, the bending direction A is along the winding direction of the wound structure in the bending region B. The electrode assembly 10 has a center line M1 in the bending region B. The center lines M1 and M2 are parallel to the winding axis Z of the electrode assembly 10 and extend along the electrode assembly 10. Figure 1 The longitudinal direction Y in the electrode assembly 10 is the width direction X, the winding axis is perpendicular to the longitudinal direction Y and the width direction X of the electrode assembly, and the longitudinal direction Y is perpendicular to the width direction X.

[0079] In one embodiment of the present application, a piece of separator 13, a piece of cathode electrode 11, another piece of separator 13 and a piece of anode electrode 12 may be stacked and then wound or folded, or at least one piece (for example, two or more pieces) of cathode electrode 11 and at least one piece (for example, two or more pieces) of anode electrode 12 and at least two separators (for example, four pieces or more, the number of separators is twice the number of cathode electrode sheets or anode electrode sheets) may be stacked and then wound or folded to form a bending area B. When the electrode assembly has multiple layers of cathode electrode sheets 11, multiple layers of anode electrode sheets 12 and multiple layers of separators 13 in the bending area B, the bending area B includes a structure in which the cathode electrode sheets 11, separators 13 and anode electrode sheets 12 are alternately distributed.

[0080] When the electrode assembly has a winding structure, the width direction of the cathode electrode sheet 11 and the anode electrode sheet 12 is parallel to the winding axis direction, and the width direction of the cathode electrode sheet 11 and the anode electrode sheet 12 is parallel to the direction perpendicular to the bending direction A; when the electrode assembly does not have a winding structure, the width direction of the cathode electrode sheet 11 and the anode electrode sheet 12 is parallel to the direction perpendicular to the bending direction A. For the simplicity of subsequent description, in this embodiment, the width direction of the cathode electrode sheet 11 and the anode electrode sheet 12, the direction perpendicular to the bending direction A and the winding axis direction are collectively referred to as the Z direction.

[0081] The surface of the anode electrode 12 has an anode active material layer composed of an anode active material, and the surface of the cathode electrode 11 has a cathode active material layer composed of a cathode active material. For example, the cathode active material can be lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate or lithium nickel cobalt manganese oxide, and the anode active material can be graphite or silicon.

[0082] like Figure 3 As shown in , the inventors discovered during the research and development process that during the use of the battery cell, the electrode assembly 10 continues to expand. Affected by the expansion and bending, the cathode electrode 11 of the electrode assembly 10 is prone to breakage in the bending area B. Each layer of the cathode electrode 11 can be equivalent to an internal resistance R, and the internal resistance of the cathode electrode 11 is greater than the internal resistance of the anode electrode 12. The resistance change of the cathode electrode 11 has a greater impact on the internal resistance of the electrode assembly. The internal resistance of the cathode electrode 11 can be roughly equivalent to the situation where the resistance of each layer of the cathode electrode 11 is connected in parallel. Assuming that there are four circles of cathode electrode 11, the equivalent internal resistance of each circle of cathode electrode 11 from the inside to the outside is R1-R4, and R1-R4 is a parallel structure. In the parallel structure, the more parallel internal resistances, the smaller the internal resistance of the electrode assembly. If some of the resistances in R1-R4 cannot be incorporated into the circuit, the total resistance of the parallel circuit will increase, causing the resistance of the electrode assembly 10 to increase. If the cathode electrode 11 breaks in the bending area B, as shown Figure 3 As shown in , the equivalent internal resistance R1 of the broken cathode electrode piece 11 cannot be connected in parallel to the circuit, and the equivalent parallel resistance is reduced, so the internal resistance of the electrode assembly 11 increases. The increase in the internal resistance of the electrode assembly 10 will lead to an increase in the charging polarization of the battery cell and a decrease in the capacity of the battery cell; in addition, the breakage of the cathode electrode piece will lead to a decrease in the effective mass of the cathode active material, and the decrease in the effective mass of the cathode active material will also lead to a decrease in the capacity of the battery cell, thereby affecting the capacity stability of the battery cell, and the decrease in the capacity of the battery cell will affect the capacity imbalance of the entire battery and worsen the performance of the entire battery. The situations in which the internal resistance increases due to the breakage of the cathode electrode piece 11 include: 1. The broken part of the cathode electrode piece 11 is not provided with a tab, and the broken part cannot be electrically connected to the top cover after the breakage; 2. The broken part of the cathode electrode piece 11 is provided with a tab, and after welding, the tab at the broken part is cracked or poorly welded, and the broken part is still not electrically connected to the top cover.

[0083] In view of this, if Figure 4As shown in the figure, the present application provides an electrode assembly 10, including a cathode electrode piece 11, an anode electrode piece 12, an isolating member 13 and a conductive layer 14, the isolating member 13 is used to isolate the cathode electrode piece 11 and the anode electrode piece 12; the cathode electrode piece 11, the isolating member 13 and the anode electrode piece 12 are wound to form a bending area B; the conductive layer 14 is configured so that at least a portion of the conductive layer 14 is arranged on the surface of the cathode electrode piece 11 in the bending area B, the cathode electrode piece 11 includes a covered area covered by the conductive layer 14, and the conductive layer 14 is connected in parallel to the covered area.

[0084] By providing a conductive layer 14 on the surface of the cathode electrode sheet 11 in the bend region B, and connecting the conductive layer 14 in parallel with the covered area of ​​the cathode electrode sheet 11, if the covered area of ​​the cathode electrode sheet 11 in the bend region B breaks, causing the internal resistance of the electrode assembly 10 to increase, the conductive layer 14 can maintain the electrical connection between the broken cathode electrode sheets 11, connecting the equivalent internal resistance of the broken cathode electrode sheets 11 into the circuit, suppressing the increase in the internal resistance of the electrode assembly 10, thereby reducing the capacity decay of the battery cells and maintaining the stability of the battery cell capacity. In addition, the conductive layer 14 can also provide reinforcement for the cathode electrode sheet 11 in the bend region B, reducing the chance of the cathode electrode sheet 11 breaking.

[0085] In the above embodiment, separator 13 has electronic insulation properties and is used to isolate adjacent cathode electrode pieces 11 and anode electrode pieces 12, preventing short circuits between adjacent cathode electrode pieces 11 and anode electrode pieces 12. Separator 13 has a large number of through-holes, allowing electrolyte ions to pass freely and having good permeability to lithium ions. Therefore, separator 13 is essentially unable to block the passage of lithium ions. For example, separator 13 includes a separator base layer and a functional layer located on the surface of the separator base layer. The separator base layer includes at least one of polypropylene, polyethylene, ethylene-propylene copolymer, polybutylene terephthalate, etc., and the functional layer can be a mixture layer of ceramic oxide and binder.

[0086] In the above embodiment, the anode electrode plate 12 includes an anode main body and an anode ear portion extending outward from the anode main body along the Z direction. At least a portion of the area along the Z direction on the surface of the anode main body is an anode active material area, which is used to coat the anode active material. The anode active material can be graphite or silicon.

[0087] In another embodiment of the present application, not only is an anode active material region provided on a partial area of ​​the surface of the anode main body, but an anode active material region is also provided on the surface of the anode ear and in the root area close to the anode main body, that is, a partial area of ​​the anode ear is the anode active material region.

[0088] In another embodiment of the present application, the anode active material region covers the entire surface of the anode main body along the direction Z.

[0089] In another embodiment of the present application, the cathode active material may not cover the entire surface of the cathode electrode 11, for example, Figure 5 FIG. 1 is a schematic diagram of the structure of a cathode electrode sheet after being unfolded along the unfolding direction D of the electrode assembly in one embodiment of the present application. The unfolding direction D is opposite to the winding direction A.

[0090] The cathode electrode 11 includes a cathode main body and at least one cathode ear 113 extending outside the cathode main body along the Z direction. At least a portion of the surface of the cathode main body is a cathode active material area 115, and the cathode active material area 115 can be coated with a cathode active material. For example, the cathode active material can be a ternary material, lithium manganese oxide or lithium iron phosphate.

[0091] In another embodiment of the present application, the surface of the cathode main body also includes a first insulating layer coating area 114 adjacent to the cathode active material area 115. The first insulating layer coating area 114 is located on the side of the cathode active material area 115 adjacent to the cathode ear portion 113. The first insulating layer coating area 114 is used to coat an insulating material for insulating and isolating the cathode active material area 115 and the cathode ear portion 113. The two surfaces of the current collector 102 of the cathode electrode piece 11 have the cathode active material area 115, and the cathode ear portion 113 is a part of the current collector 102 of the cathode electrode piece 11, wherein the material of the current collector 102 can be aluminum.

[0092] For example, the cathode active material area 115 and the first insulating layer coating area 114 are distributed at both ends along the width direction (i.e., Z direction) of the cathode main body on the surface of the cathode main body, and the cathode ear portion 113 and the first insulating layer coating area 114 belong to the same end of the cathode main body.

[0093] In another embodiment of the present application, the cathode active material region 115 and the first insulating layer coating region 114 are two substantially parallel regions on the surface of the cathode body, and are distributed in two layers along the Z direction on the surface of the cathode body.

[0094] In another embodiment of the present application, the first insulating layer coating region 114 may be located at the portion where the cathode main body and the cathode ear portion 113 are connected to each other. For example, the first insulating layer coating region 114 is located on the surface of the cathode main body and is connected to the cathode ear portion 113, and is used to separate the surface of the cathode ear portion 113 from the cathode active material region 115. In another embodiment of the present application, not only is the first insulating layer coating region 114 provided on the surface of the cathode main body, but a second insulating layer coating region is also provided on the root region of the cathode ear portion 113 near the cathode main body, and the second insulating layer coating region is used to coat an insulating material.

[0095] In another embodiment of the present application, the surface of the first insulating layer coating area 114 is coated with an insulating material, which includes an inorganic filler and a binder. The inorganic filler includes one or more of boehmite, aluminum oxide, magnesium oxide, titanium dioxide, zirconium oxide, silicon dioxide, silicon carbide, boron carbide, calcium carbonate, aluminum silicate, calcium silicate, potassium titanate, and barium sulfate. The binder includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyacrylic acid, polyacrylate, polyacrylic acid-acrylate, polyacrylonitrile-acrylic acid, and polyacrylonitrile-acrylate.

[0096] In another embodiment of the present application, each cathode electrode piece 11 may include one or two or more cathode electrode ears 113. When the cathode electrode piece 11 includes two or more cathode electrode ears 113, all cathode electrode ears 113 are located on the same side of the cathode electrode piece 11 along the Z direction.

[0097] When the cathode electrode sheet 11 and the anode electrode sheet 12 are stacked on each other, both ends of the anode active material region of the anode electrode sheet along the direction Z extend beyond the corresponding ends of the cathode active material region 115 of the adjacent cathode electrode sheet 11. This allows the electrode assembly to have a good energy density. For example, the two ends of the anode active material region along the direction Z are respectively a first end and a second end, and the two ends of the cathode active material region along the direction Z are respectively a third end and a fourth end, wherein the first end of the anode active material region and the third end of the cathode active material region 115 are located on the same side of the electrode assembly along the direction Z, and the first end of the anode active material region extends beyond the third end of the cathode active material region along the direction Z, the second end of the anode active material region and the fourth end of the cathode active material region 115 are located on the other side of the electrode assembly along the direction Z, and the second end of the anode active material region extends beyond the fourth end of the cathode active material region 115 along the direction Z.

[0098] The dimensions of the two ends of the anode active material region along the winding axis Z that extend beyond the corresponding ends of the cathode active material region 115 may be the same or different. For example, the extent of the extension may be in the range of 0.2 mm to 5 mm.

[0099] In some embodiments, at least a portion of the conductive layer 14 is disposed at the first bending portion 111B and / or the second bending portion 112B of the cathode electrode 11 in the bending region B. During the use of the battery cell, the anode electrode 12 expands more than the cathode electrode 11. Since the cathode electrode 11 wraps the anode electrode 12, the large expansion of the anode electrode 12 will cause the cathode electrode 11 wrapped around the outside of the anode electrode 12 to be subjected to excessive force, especially at the first bending portion 111B and the second bending portion 112B where the bending angle is larger, the cathode electrode 11 is prone to breakage. The conductive layer 14 is disposed at the first bending portion 111B and / or the second bending portion 112B of the cathode electrode 11 in the bending region B. The conductive layer 14 can also strengthen the first bending portion 111B and / or the second bending portion 112B of the cathode electrode, thereby reducing the situation where the covered area of ​​the cathode electrode 11 breaks and the internal resistance of the electrode assembly 10 increases, thereby improving the capacity stability of the battery cell. Figure 4 The conductive layer 14 shown in FIG is disposed on the radially inner surface of the first bending portion 111B of the cathode electrode 11, and the conductive layer 14 is entirely located within the bending region B. In some embodiments, the conductive layer 14 may cover all or a portion of the cathode electrode 11 in the bending region B, that is, the conductive layer 14 may cover all or a portion of the first bending portion 111B and / or the second bending portion 112B of the cathode electrode 11 in the bending region B. In other embodiments, a portion of the conductive layer 14 is located within the bending region B, and another portion extends into the straight region C.

[0100] In this embodiment, the winding structure of the electrode assembly 10 includes a straight area C and a bending area B, and the bending area B includes a first bending area B1 and a second bending area B2 located on both sides of the straight area C, wherein the straight area C and the first bending area B1 and the second bending area B2 are respectively divided by straight dotted lines.

[0101] The electrode assembly includes anode plates 12 and cathode plates 11 alternately stacked in the first bending region B1 and the second bending region B2, with separators 13 between adjacent anode plates 12 and cathode plates 11. The innermost plates in the first bending region B1 and the second bending region B2 are both anode plates 12, and the inner surface of at least the innermost cathode plates 11 in the first bending region B1 and the second bending region B2 is provided with a conductive layer 14. For example, the inner surface of each layer of cathode plates 11 in the first bending region B1 and the second bending region B2 is provided with a conductive layer 14. In this embodiment, the radial inner surface of the cathode plate 11 refers to the surface of the cathode plate 11 facing the winding axis, or the surface facing the inside of the winding structure.

[0102] For example, the first bending area B1 has multiple layers of pole pieces, such as five layers of pole pieces. Along the winding structure from the inside to the outside, the anode pole piece 12 and the cathode pole piece 11 of the first bending area B1 are alternately stacked in sequence. The innermost pole piece of the first bending area B1 is the first bending portion 121B of the anode pole piece 12, and its radial outer side is the first bending portion 111B of the cathode pole piece 11. The conductive layer 14 is attached to the inner surface of the first bending portion 111B of the cathode pole piece 11 of the first bending area B1.

[0103] The second bending area B2 has multiple layers of pole pieces, for example, three layers of pole pieces. The innermost layer (also called the first layer) and the outermost layer (also called the third layer) of the second bending area B2 are both anode pole pieces 12, and the pole piece between the innermost pole piece and the outermost pole piece (also called the second layer pole piece) is the cathode pole piece 11. The second bending portion 122B of the anode pole piece 12 is the innermost pole piece of the first bending area B1, and its radial outer side is the second bending portion 112B of the cathode pole piece 11.

[0104] In some embodiments, the conductive layer 14 may be a single-layer structure. The material of the conductive layer 14 includes a metal-based conductive material such as silver, gold, nickel, copper, or aluminum, or a non-metal-based conductive material such as polypyrrole, polyphenylene sulfide, polyphthalocyanine, polyaniline, or polythiophene, or a mixture of one or more of the above materials. The conductive layer may also be made of other conductive materials.

[0105] The conductive layer 14 can be electrically connected to the cathode electrode 11 by bonding with a conductive glue. The conductive glue can be a metal-based conductive paste including silver, gold, nickel, copper, and aluminum paste, or a non-metal-based conductive paste such as polypyrrole, polyphenylene sulfide, polyphthalocyanine compounds, polyaniline, polythiophene glue, etc., as well as a mixture of one or more of the above materials.

[0106] In some embodiments, a conductive layer 14 is provided on one or both surfaces of the cathode electrode sheet 11. By providing a conductive layer 14 on one or both surfaces of the cathode electrode sheet 11, it is possible to more effectively suppress the occurrence of fracture of the cathode electrode sheet 11 in the bending region B, which leads to an increase in the internal resistance of the electrode assembly, and to provide reinforcement for the cathode electrode sheet 11 in the bending region B, thereby reducing the occurrence of fracture in the covered area of ​​the cathode electrode sheet. One or both surfaces of the cathode electrode sheet 11 refer to the surfaces of the cathode electrode sheet 11 located on the inner and / or outer sides of the radial direction along the winding direction. Figure 4As shown in , the conductive layer 14 is arranged on the inner surface of the cathode electrode 11 in the radial direction. When the anode electrode 12 expands, the radial inner surface of the cathode electrode 11 is subjected to an extrusion force, while the outer surface of the cathode electrode 11 is subjected to a tensioning force, and the tensioning force of the outer surface is greater than the extrusion force on the inner side. Providing the conductive layer 14 on the inner side of the cathode electrode 11 in the radial direction can reduce the force on the conductive layer 14 and reduce the risk of failure of the conductive layer 14. Providing the conductive layer 14 on both the inner and outer surfaces of the cathode electrode 11 can provide better reinforcement for the cathode electrode 11 in the bending area B, and when the cathode electrode 11 in the bending area B is broken, the conductive layers 14 on the two surfaces can provide a smoother conductive path, reducing the increase in the internal resistance of the electrode assembly 10.

[0107] like Figure 6 As shown in , in some embodiments, the electrode assembly 10 is an electrode assembly for a cylindrical battery. In this embodiment, the first bending portion 111B of the cathode electrode sheet 11 refers to the first turn of the cathode electrode sheet 11 from the inside to the outside in the radial direction; the second bending portion refers to the second turn of the cathode electrode sheet 11 from the inside to the outside in the radial direction, and so on. The conductive layer 14 is disposed at the first bending portion 111B, which means that the conductive layer is disposed on the first turn of the cathode electrode sheet from the inside to the outside in the radial direction.

[0108] like Figure 7 As shown in FIG, in another embodiment of the present application, a conductive layer 141 is provided on the radial inner surface of the first bend 111B of the cathode electrode sheet 11, and a conductive layer 142 is provided on the radial inner surface of the second bend 112B. Because the wound structure of the electrode assembly has two bends B1 and B2, both bends B1 and B2 are subject to expansion forces during expansion. Providing conductive layers at both bends 111B and 112B of the cathode electrode sheet 11 ensures that the forces on both bends B1 and B2 are evenly distributed.

[0109] like Figure 8 As shown in , in another embodiment of the present application, a conductive layer 141 is provided on the radial inner surface of the first bending portion 111B of the cathode electrode piece 11, and a conductive layer 143 is provided on the radial outer surface of the first bending portion 111B of the cathode electrode piece 11; a conductive layer 142 is provided on the radial inner surface of the second bending portion 112B of the cathode electrode piece 11, and a conductive layer 144 is provided on the radial outer surface of the first bending portion 111B of the cathode electrode piece 11. Providing a conductive layer 14 on both the inner and outer surfaces of the cathode electrode piece 11 can provide better reinforcement for the cathode electrode piece 11 in the bending region B, and when the cathode electrode piece 11 in the bending region B is broken, the conductive layers 14 on both the inner and outer surfaces can provide a smoother conductive path, thereby reducing the increase in the internal resistance of the electrode assembly 10.

[0110] like Figure 9 As shown in , in some embodiments, the conductive layer 14 is further disposed at the first bending portion 121B and / or the second bending portion 121B of the anode electrode sheet 12 in the bending region B, and is connected in parallel with the anode electrode sheet 12. During use of the battery cell, the anode electrode sheet 12 expands. The bending angles of the first bending portion 121B and the second bending portion 122B of the anode electrode sheet 12 in the bending region B are relatively large. Under the influence of the expansion force, the anode active material layer at the first bending portion 121B and the second bending portion 122B of the anode electrode sheet 12 is prone to fracture or detachment, or the anode electrode sheet 12 may fracture. A conductive layer 14 is provided at the first bending portion 121B and the second bending portion 122B of the anode electrode sheet 12 in the bending region B. The conductive layer 14 can also strengthen the first bending portion 12B and the second bending portion 122B of the anode electrode sheet 12, thereby reducing the anode active material layer from breaking or falling off due to bending of the anode electrode sheet 12, or the occurrence of a breakage of the anode electrode sheet 12. If the anode active material layer breaks or falls off, it will cause insufficient lithium embedding space in the anode electrode sheet 12 during charging, resulting in lithium deposition. The conductive layer 14 can reduce the anode active material layer from breaking or falling off due to bending of the anode electrode sheet 12, thereby reducing the occurrence of lithium deposition. If the anode electrode sheet 12 breaks, and the broken portion of the anode electrode sheet 12 is not conductive and lacks a receiving site, lithium deposition will also occur. The conductive layer 14 is connected in parallel to the anode electrode sheet 12, and after the anode electrode sheet 12 breaks, the broken portion of the anode electrode sheet 12 can be kept conductive, thereby reducing lithium deposition and at the same time providing reinforcement to the anode electrode sheet, thereby reducing the occurrence of breakage. In some embodiments, disposing the conductive layer 14 on the surface of the anode electrode 12 adjacent to the cathode electrode 11 can reduce the occurrence of lithium plating.

[0111] like Figure 9 As shown in , in some embodiments of the present application, a conductive layer 141 is provided on the radial inner surface of the first bending portion 111B of the cathode pole piece 11, and a conductive layer 142 is provided on the radial inner surface of the second bending portion 112B of the cathode pole piece 11; a conductive layer 145 is provided on the radial outer surface of the first bending portion 121B of the anode pole piece 12, and a conductive layer 146 is provided on the radial outer surface of the second bending portion 122B of the anode pole piece 12.

[0112] like Figure 10 As shown in , in some embodiments, a portion of the conductive layer 14 is located within the bending region B, and another portion extends into the straight region C. Specifically, the conductive layer 145 provided on the radially outer surface of the first bending portion 121B of the anode electrode piece 12 and the conductive layer 141 provided on the radially inner surface of the first bending portion 111B of the cathode electrode piece 11 are both configured so that a portion is located within the bending region B and another portion extends into the straight region C, so that the conductive layer 14 has as large an area as possible in the bending region B.

[0113] In another embodiment of the present application, both ends of the conductive layer 14 extending along the bending direction A are located in the bending region B, that is, the entire conductive layer 14 is located in the bending region B. In this embodiment, the electrode assembly further includes a straight region C connected to the bending region B. The bending direction A refers to a direction along the curved surface of the bending region B and pointing to the straight region C. The direction perpendicular to the bending direction A refers to a direction perpendicular to the bending direction A.

[0114] In another embodiment of the present application, one end of the conductive layer 14 extending along the bending direction A is located in the straight region C, and the other end is located in the bending region B.

[0115] In another embodiment of the present application, both ends of the conductive layer 14 extending along the bending direction A are located at the junction of the bending area B and the straight area C, or both ends of the conductive layer 14 extending along the bending direction A are close to the junction of the bending area B and the straight area C.

[0116] like Figure 11 As shown in , in another embodiment of the present application, a conductive layer 4 is provided on the inner and outer surfaces of the cathode electrode piece 11, as well as on the anode electrode piece 12. A conductive layer 141 is provided on the radial inner surface of the first bending portion 111B of the cathode electrode piece 11, and a conductive layer 142 is provided on the radial inner surface of the second bending portion 112B of the cathode electrode piece 11; a conductive layer 143 is provided on the radial outer surface of the first bending portion 111B of the cathode electrode piece 11, and a conductive layer 144 is provided on the radial outer surface of the second bending portion 112B of the cathode electrode piece 11; a conductive layer 145 is provided on the radial outer surface of the first bending portion 121B of the anode electrode piece 12, and a conductive layer 146 is provided on the radial outer surface of the second bending portion 122B of the anode electrode piece 12.

[0117] Figure 4 、 6 The structure of the conductive layer 14 of embodiment -11 is not limited to being applied to the first bending portion or the second bending portion of the cathode electrode piece or the anode electrode piece, but can also be applied to the third bending portion and above. Figure 4 、 6 The structures of the conductive layer 14 of the embodiment of -11 can also be combined with each other.

[0118] The structure of the conductive layer 14 is described below with reference to the accompanying drawings, taking the conductive layer 14 provided at the first bending area B1 as an example. However, the structure of the conductive layer 14 in the following embodiments is not limited to the first bending area B1, but may also be applicable to the second bending area B1 or other parts, as well as the conductive layer on the anode electrode.

[0119] like Figure 12 As shown, Figure 5In the cross-sectional structural diagram along the EE direction, the conductive layer 14 includes a conductive base layer 1402 . In the bending region, the conductive base layer 1402 is connected in parallel to the cathode electrode 12 .

[0120] In any embodiment of the present application, the material of the conductive base layer 1402 includes a metal-based conductive material, including silver, gold, nickel, copper, aluminum, or a non-metal-based conductive material, such as polypyrrole, polyphenylene sulfide, polyphthalocyanine compound, polyaniline, polythiophene, or a mixture of one or more of the above materials. The conductive layer 14 can also be made of other conductive materials. The conductive base layer 1402 strengthens the cathode electrode 11, reduces the situation where the internal resistance of the electrode assembly 10 increases due to the breakage of the cathode electrode 11, and thereby improves the capacity stability of the battery cell.

[0121] The conductive base layer 1402 can be electrically connected to the cathode electrode 11 by bonding with a conductive adhesive. In any embodiment of the present application, the conductive adhesive can be a metal-based conductive paste including silver, gold, nickel, copper, and aluminum paste, or a non-metal-based conductive paste such as polypyrrole, polyphenylene sulfide, polyphthalocyanine, polyaniline, polythiophene paste, etc., or a mixture of one or more of the above materials.

[0122] Combine Figure 5 The conductive base layer 1402 is electrically connected to the cathode active material region 115 of the cathode electrode 11 .

[0123] like Figure 13 As shown in FIG, in the bending region B, the entire surface of the conductive base layer 1402 adjacent to the cathode electrode sheet 11 is electrically connected to the covered region 11F of the cathode electrode sheet 11. Along the winding direction of the electrode assembly 10, the center line M1 of the bending region B passes through the conductive base layer 14. The bending angle of the cathode electrode sheet 11 at the center line M1 of the bending region B1 is large, and the possibility of fracture is greater. Along the winding direction A of the electrode assembly 10, the center line M1 of the bending region B1 passes through the conductive base layer 14. When the cathode electrode sheet 11 fractures near the center line M1, the conductive base layer 14 can cover the fractured portion of the cathode electrode sheet 11. Since the entire surface of the conductive base layer 14 adjacent to the cathode electrode sheet 11 is electrically connected to the cathode electrode sheet 11, the two fractured portions of the cathode electrode sheet 11 can still be electrically connected through the conductive base layer 14, thereby suppressing the increase in the internal resistance of the electrode assembly 10.

[0124] like Figure 13In another embodiment shown in , the conductive layer 14 further includes an ion blocking layer 1401, which is arranged on the side of the conductive base layer 1402 away from the cathode electrode 11 and covers the conductive base layer 1402. The ion blocking layer 1401 is used to block at least a portion of the ions from escaping from the cathode electrode 11 located on the side of the ion blocking layer 1401. During charging, the conductive base layer 1402 will block some ions from escaping from the active material area 115 of the cathode electrode 11, but some ions may still diffuse outward from the edge of the conductive base layer 1402. The ion blocking layer 1401 covers the side of the conductive base layer 1402 away from the cathode electrode 11, and can block some ions from escaping from the cathode active material area 115 of the cathode electrode 11 located on the side of the ion blocking layer 1401 and embedding into the anode electrode 12 adjacent to the cathode electrode 11. The ion blocking layer 1401 mainly blocks the ions diffused from the edge of the conductive base layer 1402 from embedding into the anode electrode 12 adjacent to the cathode electrode 11, which can reduce the occurrence of lithium deposition in the anode electrode 12 in the bending area B.

[0125] like Figure 14 As shown in Figure 13 An exploded view of an embodiment of the middle conductive layer 14 . In this embodiment, the area of ​​the ion blocking layer 1401 is greater than or equal to the area of ​​the conductive base layer 1402 and covers the edge of the conductive base layer 1402 .

[0126] like Figure 15 As shown in Figure 13 An exploded view of another embodiment of the conductive layer 14, Figure 16 for Figure 15 The plan view of the combined state of the conductive layer 14. In this embodiment, Figure 14 The difference between the embodiment and the embodiment is that there are multiple conductive base layers 1402, which are arranged at intervals along the direction parallel to the winding axis Z of the electrode assembly 10, and each conductive base layer 1402 is connected in parallel with the covered area 11F of the corresponding cathode plate 11 covered by the conductive base layer 1402. Figure 14 The conductive substrate 1402 is a single unit, with multiple conductive substrates 1402 arranged at intervals. Because the forces applied to different locations of the electrode assembly may vary, the conductive substrates 1402 are spaced apart. The conductive substrates 1402 located at locations subject to greater force in the electrode assembly experience greater force, while those located elsewhere experience less force. This disperses the force applied to the conductive substrates 1402 and reduces the likelihood of breakage. Furthermore, while ensuring conductivity, the space occupied by the conductive substrates 1402 can be reduced, thereby increasing the energy density of the battery cells.

[0127] like Figure 17As shown in , in other embodiments, in the bending region B, along the winding direction A of the electrode assembly 10, the conductive base layer 1402 includes two end portions 1402a located on both sides of the center line M1 of the bending region B, and the two end portions 1402a are respectively electrically connected to the covered area 11F of the cathode electrode 11.

[0128] In this embodiment, the bending angle of the cathode electrode 11 at the center line M1 of the bending area B is large, and the possibility of breakage is greater; along the winding direction of the electrode assembly 10, the center line M1 of the bending area B passes through the conductive base layer 1402. When the cathode electrode 11 breaks near the center line, the conductive base layer 1402 can cover the broken part of the cathode electrode 11. Since the two ends of the conductive base layer 1402 on both sides of the center line M1 of the bending area B are respectively electrically connected to the covered area 11F of the cathode electrode 11, the two broken parts of the cathode electrode 11 can still be electrically connected through the conductive base layer 1402, thereby suppressing the increase in the internal resistance of the electrode assembly 10.

[0129] In this embodiment, the conductive base layer 1402 also includes a main body 1402b, which is connected to the two end portions 1402a; the conductive layer 14 also includes an ion blocking layer 1401, which is arranged between the main body 1402b of the conductive base layer 1402 and the cathode electrode 11, and the ion blocking layer 1401 is used to block at least a part of the ions from escaping from the cathode electrode 11 located on one side of the ion blocking layer 1401.

[0130] In this embodiment, an ion blocking layer 1401 is arranged between the main body 1402b of the conductive base layer 1402 and the cathode electrode 11. The ion blocking layer 1401 is attached to the surface of the cathode electrode 11 and directly covers the cathode active material area 115 of the cathode electrode 11. It can better block a part of the ions from escaping from the cathode electrode 11 and embedding into the adjacent anode electrode 12, thereby reducing the occurrence of lithium deposition in the bending area of ​​the anode electrode 12.

[0131] like Figure 18 As shown in Figure 17 An exploded view of an embodiment of the conductive layer 14. In this embodiment, along the winding direction, the length of the ion blocking layer 1401 is less than the length of the conductive base layer 1402, and the conductive base layer 1402 exceeds the two ends of the ion blocking layer 1401 to form an end 1402a electrically connected to the cathode electrode 11, and the part between the two ends 1402a forms the main body 1402b.

[0132] like Figure 19 As shown in Figure 17 Exploded view of another embodiment of the conductive layer 14. In this embodiment, Figure 17The difference between the embodiment in the embodiment is that there are multiple conductive base layers 1402, which are arranged at intervals along the direction parallel to the winding axis Z of the electrode assembly 10, and each conductive base layer 1402 is connected in parallel with the covered area 11F of the corresponding cathode electrode piece 11 covered by the conductive base layer 1402. Specifically, the two end portions 1402a of each conductive base layer 1402 are respectively electrically connected to the covered area 11F of the corresponding cathode electrode piece 11 covered by the conductive base layer 1402. In this embodiment, compared Figure 17 The conductive base layer 1402 is a single unit, and multiple conductive base layers 1402 are arranged at intervals. This reduces the space occupied by the conductive base layers 1402 while ensuring conductivity, thereby increasing the energy density of the battery cell. Furthermore, even if one or more of the corresponding covered areas 11F of the multiple conductive base layers 1402 are broken, as long as at least one conductive base layer 1402 remains conductive, the broken electrode pieces can remain electrically connected, thus improving reliability.

[0133] like Figure 20 FIG. 1 shows the structure of the conductive layer 14 of another embodiment. Figure 17 The difference between the embodiments in FIG and FIG is that the conductive layer 14 further includes an insulating layer 1403, which is disposed on the side of the conductive base layer 1402 away from the cathode electrode 11 and covers the conductive base layer 1402. In this embodiment, the insulating layer 1403 is disposed on the side of the conductive base layer 1402 away from the cathode electrode 11 and covers the conductive base layer 1402. When the separator 13 in the bending region B ruptures, the insulating layer 1403 prevents the conductive base layer 1402 from directly contacting the anode electrode 12 and causing a short circuit between the cathode electrode 11 and the anode electrode 12. In this embodiment, the area of ​​the insulating layer 1403 is greater than or equal to the area of ​​the conductive base layer 1402 and covers the edges of the conductive base layer 1402.

[0134] Figure 21 Shown in Figure 18 On the basis of the embodiment of FIG, an insulating layer 1403 is provided on the side of the conductive base layer 1402 away from the cathode electrode 11. In some embodiments not shown, the insulating layer 1403 may also be provided on the conductive base layer 1402. Figure 19 On the basis of the embodiment of FIG. 1 , an insulating layer is provided on the side of the conductive base layer 1402 away from the cathode electrode 11 .

[0135] In any embodiment of the present application, the material of the ion blocking layer 1402 includes magnesium oxide, calcium oxide, boehmite, wollastonite, barium sulfate, calcium sulfate, calcium carbonate, aluminum oxide, silicon dioxide, polyethylene, polyvinyl chloride, polyacrylic acid / acrylate, styrene-butadiene, styrene-acrylic acid, ethylene-vinyl acetate copolymer, polypropylene, polyvinylidene fluoride, carboxymethyl cellulose, epoxy glue, organic silicone, polyurethane glue, styrene-isoprene-styrene copolymer glue and at least one of the modifications of the above substances.

[0136] In any embodiment of the present application, the material of insulating layer 1403 is selected from an organic polymer insulating material, an inorganic insulating material, and a composite material. The material of the insulating layer is selected from an organic polymer insulating material, and the organic polymer insulating material is selected from at least one of polyamide, polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly(p-phenylene terephthalamide), epoxy resin, polyoxymethylene, phenolic resin, polypropylene, polytetrafluoroethylene, silicone rubber, polyvinylidene fluoride, polycarbonate, aramid, poly(phenylene dicarboxamide), cellulose and its derivatives, starch and its derivatives, protein and its derivatives, polyvinyl alcohol and its cross-linked products, polyethylene glycol and its cross-linked products. In any embodiment of the present application, the composite material is composed of an organic polymer insulating material and an inorganic insulating material. In some embodiments, the composite material is selected from at least one of epoxy resin glass fiber reinforced composite material and polyester resin glass fiber reinforced composite material. In any embodiment of the present application, the inorganic insulating material is selected from at least one of aluminum oxide, silicon carbide, and silicon dioxide.

[0137] Figure 22 Shown Figure 4 Schematic diagram of the cross-sectional structure of an embodiment at the position M1 along the winding axis Z direction, a conductive layer 14 is arranged on the surface of the cathode plate 11 along the winding axis Z direction of the electrode assembly.

[0138] Figure 23 Shown Figure 4 A schematic diagram of a cross-sectional structure of another embodiment at the position M1 along the winding axis Z direction, and Figure 22 The difference between the embodiments is that multiple conductive layers 14 are arranged on the surface of the cathode electrode sheet 11 along the winding axis Z of the electrode assembly. The multiple conductive layers 14 are spaced apart along the winding axis Z of the electrode assembly, and each conductive layer 14 is connected in parallel with the covered area 11F of the corresponding cathode electrode sheet 11. Because the forces applied to the electrode assembly may vary at different locations, the conductive layers 14 are spaced apart. The conductive layers 14 located at locations where the electrode assembly is subjected to greater forces are subjected to greater forces, while the conductive layers 14 at other locations are subjected to less force. This disperses the forces applied to the conductive layers 14 and reduces the possibility of fracture of the conductive layers 14. In addition, while ensuring the conductive effect, the space occupied by the conductive layers 14 can be reduced, thereby increasing the energy density of the battery cell. Figure 22 and Figure 23 The conductive layer 14 of the embodiment can be made of Figure 12-21 The structure of the conductive layer 14 in the embodiment.

[0139] In some embodiments, the total flow area of ​​the conductive base layer 1402 is greater than or equal to 1 / 3 of the flow area of ​​the current collector 102 of the connected cathode electrode 11, so as to avoid the conductive base layer 1402 temperature rising due to the small flow area and falling off from the cathode electrode, thereby ensuring safe use. Figure 15 or Figure 19 As shown in the embodiment, when a conductive layer includes multiple parallel conductive base layers 1402, the total flow area of ​​the conductive base layers refers to the sum of the flow areas of the multiple conductive base layers 1402. Figure 23 As shown, when the conductive layer 14 includes multiple parallel conductive layers 14, the total flow area of ​​the conductive base layer 1402 is the sum of the flow areas of the conductive base layers 1402 of all the conductive layers 14. The flow area of ​​each conductive base layer 1402 is the cross-sectional area of ​​the conductive base layer 1402 along the winding axis Z direction of the electrode assembly 10. Figure 28 As shown in , when conductive layers 14 are provided on both surfaces of the cathode electrode sheet, the total flow area of ​​the conductive base layer 1402 is equal to the sum of the flow areas of the conductive layers 141 and 143 on the two surfaces. The flow area of ​​the current collector 102 of the cathode electrode sheet 11 is the cross-sectional area of ​​the current collector 102 along the winding axis Z direction of the electrode assembly 10.

[0140] Figures 12 to 23 The embodiment only briefly describes the positional relationship between the conductive layer 14 and the cathode electrode 11 and the structural features of the conductive layer 14. Figures 12 to 23 The conductive layer is not limited to being provided on the cathode electrode piece 11 , but may also be provided on the anode electrode piece 12 . Figures 12 to 23 The structure of the conductive layer 14 of the embodiment can be applied alone or in combination Figure 4-11 In the structure of the electrode assembly 10 of any embodiment.

[0141] like Figure 24 FIG2 is a schematic diagram of the structure of a battery cell according to another embodiment of the present application. The battery cell includes a housing 20 and one or more electrode assemblies 10 accommodated in the housing 20. The housing 20 includes a shell 21 and a cover plate 22. The shell 21 has a receiving cavity and an opening, that is, the plane does not have a shell wall, so that the inside and outside of the shell 21 are connected, so that the electrode assembly 10 can be accommodated in the receiving cavity of the shell 21. The cover plate 22 is combined with the shell 21 at the opening of the shell 21 to form a hollow cavity. After the electrode assembly 10 is accommodated in the shell 20, the shell 20 is filled with electrolyte and sealed.

[0142] The housing 21 is determined by the shape of one or more electrode assemblies 10 after assembly. For example, the housing 21 may be a hollow cuboid, a hollow cube, or a hollow cylinder. For example, when the housing 21 is a hollow cuboid or a cube, one of the planes of the housing 21 is an open surface, i.e., the plane does not have a housing wall, allowing the inside and outside of the housing 21 to communicate. When the housing 21 is a hollow cylinder, one of the circular side surfaces of the housing 21 is an open surface, i.e., the circular side surface does not have a housing wall, allowing the inside and outside of the housing 21 to communicate.

[0143] In another embodiment of the present application, the housing 21 may be made of a conductive metal material or plastic. Optionally, the housing 21 is made of aluminum or an aluminum alloy.

[0144] The structure of the electrode assembly 10 can refer to the aforementioned Figure 4-23 The relevant contents of the electrode assembly described in the embodiment will not be repeated here.

[0145] like Figure 25 FIG. 1 is a schematic diagram of the structure of a battery module according to another embodiment of the present invention. The battery module 6 includes a plurality of interconnected battery cells 7, wherein the plurality of battery cells 7 can be connected in series, in parallel, or in hybrid connection. Hybrid connection means that the connection includes both series and parallel connection. The structure of the battery cell 7 can refer to FIG. Figure 24 The battery cells described in the corresponding embodiments are not described in detail here.

[0146] Figure 26 This is a schematic diagram of the structure of a battery according to another embodiment of the present invention. The battery 2 includes a box 5, and the box 5 contains a plurality of battery cells 7. The structure of the battery cell 7 can be referred to Figure 25 The structure of the battery cell 7 is shown. The specific manner of accommodating multiple battery cells 7 in the box 5 may include: directly installing the battery cell 7 in the box 5, or assembling multiple battery cells 7 into a battery module, and then installing the battery module in the battery 2.

[0147] like Figure 26 As shown in , in some embodiments, the battery 2 includes multiple battery modules 6 and a box body 5, the box body includes a lower box body 52 and an upper box body 51, and the multiple battery modules 6 can be connected in series, in parallel, or mixed. The lower box body 52 has a accommodating cavity, and the lower box body 52 has an opening so that the multiple connected battery modules 6 can be accommodated in the accommodating cavity of the lower box body 52. ​​The upper box body 51 and the lower box body 52 are combined at the opening of the lower box body 52 to form a hollow cavity, and the upper box body 51 and the lower box body 52 are sealed after being combined.

[0148] In another embodiment of the present application, the battery can independently power an electrical device, and the battery can be called a battery pack, for example, used to power a car.

[0149] In another embodiment of the present application, according to the power demand of the electrical device, multiple batteries are connected to form a battery pack to supply power to the electrical device. In another embodiment of the present application, the battery pack can also be housed in a box and encapsulated.

[0150] To simplify the description, the following embodiments are described using an example in which the electrical device includes a battery.

[0151] In one embodiment of the present application, there is also provided an electric device, for example, the electric device may be a car, for example, a new energy vehicle, and the electric device includes the battery described in the above embodiment, wherein the battery used in the electric device may be as follows Figure 26 The batteries described in the corresponding embodiments are not described in detail here.

[0152] For example, Figure 27 The figure shows a schematic structural diagram of an electric device according to another embodiment of the present application. The electric device may be a car. The car 1 may be a fuel car, a gas car or a new energy car. The new energy car may be a pure electric car, a hybrid car or an extended-range car, etc. The car includes a battery 3, a controller 2 and a motor 4. The battery 3 is used to supply power to the controller 2 and the motor 4 as the operating power supply and driving power supply of the car 1. For example, the battery 3 is used to meet the working power requirements during the start-up, navigation and operation of the car. For example, the battery 3 supplies power to the controller 2, the controller 2 controls the battery 3 to supply power to the motor 4, and the motor 4 receives and uses the power of the battery 3 as the driving power supply of the car 1, replacing or partially replacing fuel or natural gas to provide driving power for the car.

[0153] like Figure 28 FIG. 1 is a flow chart of a method for processing an electrode assembly according to another embodiment of the present application, the method comprising:

[0154] Step 100: providing a cathode electrode piece, an anode electrode piece, and a separator;

[0155] Step 200: providing a conductive layer, disposing the conductive layer at a predetermined position of a cathode electrode, wherein the cathode electrode includes a covered area covered by the conductive layer, and connecting the conductive layer and the covered area in parallel;

[0156] Step 300: Winding the cathode electrode sheet, the anode electrode sheet and the separator, wherein the cathode electrode sheet, the separator and the anode electrode sheet are wound to form a bending region, and the preset position is configured so that at least a portion of the conductive layer is located in the bending region after winding.

[0157] like Figure 29As shown, it is a structural schematic diagram of a processing device for an electrode assembly according to another embodiment of the present application, the processing device 400 includes: a providing device 410 for providing a cathode electrode sheet, an anode electrode sheet, an isolating member and a conductive layer; a connecting device 420, a connecting device for connecting the conductive layer to the cathode electrode sheet at a preset position of the cathode electrode sheet, the cathode electrode sheet includes a covered area covered by the conductive layer, and the connecting device 420 is used to connect the conductive layer and the covered area in parallel; a winding device 430, for winding the cathode electrode sheet, the anode electrode sheet and the isolating member, the cathode electrode sheet, the isolating member and the anode electrode sheet are wound to form a bending area, and the preset position is configured so that at least a portion of the conductive layer is located in the bending area after winding.

[0158] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of this application and to form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0159] 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 make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrode assembly, characterized in that: include: A cathode electrode sheet, an anode electrode sheet, and a separator, wherein the separator is used to separate the cathode electrode sheet from the anode electrode sheet, the cathode electrode sheet includes a cathode current collector and a cathode active material layer coated on the surface of the cathode current collector, and the anode electrode sheet includes an anode current collector and an anode active material layer coated on the surface of the anode current collector; the cathode electrode sheet, the separator, and the anode electrode sheet are wound to form a bent region and a straight region, wherein the bent region is located on both sides of the straight region, and the bent region includes multiple bent portions; The conductive layer is configured to be arranged on the surface of the cathode active material layer of the cathode electrode in the bending area, the cathode active material layer of the cathode electrode includes a covered area covered by the conductive layer, the conductive layer is connected in parallel to the covered area, and each conductive layer only covers one bending part.

2. The electrode assembly according to claim 1, wherein The conductive layer is provided on one surface or both surfaces of the cathode electrode.

3. The electrode assembly according to claim 1, wherein At least a portion of the conductive layer is disposed at a first bending portion and / or a second bending portion of the cathode electrode in a bending region.

4. The electrode assembly according to claim 1, wherein The conductive layer is further arranged at the first bending portion of the anode electrode sheet and / or the second bending portion of the anode electrode sheet in the bending region, and is connected in parallel with the anode electrode sheet.

5. The electrode assembly according to claim 1, wherein The conductive layer includes a conductive base layer, and in the bending area, the conductive base layer is connected in parallel with the cathode electrode.

6. The electrode assembly according to claim 5, wherein: In the bending area, the entire surface of the conductive base layer on the side adjacent to the cathode electrode is electrically connected to the covered area, and along the winding direction of the electrode assembly, the center line of the bending area passes through the conductive base layer.

7. The electrode assembly according to claim 6, wherein: The conductive layer further includes The ion blocking layer is arranged on the side of the conductive base layer away from the cathode electrode and covers the conductive base layer. The ion blocking layer is used to block at least a part of ions from escaping from the cathode electrode located on the side of the ion blocking layer.

8. The electrode assembly according to claim 5, wherein: In the bending region, along the winding direction of the electrode assembly, the conductive base layer includes two end portions located on both sides of a center line of the bending region, and the two end portions are electrically connected to the covered region respectively.

9. The electrode assembly according to claim 8, wherein The conductive base layer also includes a main body portion, which is connected to the two end portions; the conductive layer also includes an ion blocking layer, which is arranged between the main body portion of the conductive base layer and the cathode electrode piece, and the ion blocking layer is used to block at least a part of the ions from escaping from the cathode electrode piece located on one side of the ion blocking layer.

10. The electrode assembly according to claim 6, wherein The conductive layer further includes an insulating layer, which is arranged on a side of the conductive base layer away from the cathode electrode and covers the conductive base layer.

11. The electrode assembly according to any one of claims 5 to 9, wherein: There are a plurality of conductive base layers, and the plurality of conductive base layers are arranged at intervals along a direction parallel to the winding axis of the electrode assembly.

12. The electrode assembly according to any one of claims 5 to 9, wherein: The total flow area of ​​the conductive base layer is greater than or equal to 1 / 3 of the flow area of ​​the current collector of the connected cathode electrode.

13. The electrode assembly according to claim 7 or 9, wherein: The material of the ion barrier layer includes magnesium oxide, calcium oxide, boehmite, wollastonite, barium sulfate, calcium sulfate, calcium carbonate, aluminum oxide, silicon dioxide, polyethylene, polyvinyl chloride, polyacrylic acid / acrylate, styrene-butadiene, styrene-acrylic acid, ethylene-vinyl acetate copolymer, polypropylene, polyvinylidene fluoride, carboxymethyl cellulose, epoxy glue, organic silica gel, polyurethane glue, styrene-isoprene-styrene copolymer glue and at least one of the modified products of the above materials.

14. The electrode assembly according to any one of claims 5 to 9, wherein: The material of the conductive base layer includes at least one of silver, gold, nickel, copper, aluminum, polypyrrole, polyphenylene sulfide, polyphthalocyanine compounds, polyaniline, and polythiophene.

15. The electrode assembly according to any one of claims 1 to 9, wherein: There are multiple conductive layers, and the multiple conductive layers are arranged at intervals along a direction parallel to the winding axis of the electrode assembly.

16. A battery cell comprising: A shell, an electrolyte, a cover plate and at least one electrode assembly according to any one of claims 1 to 15, characterized in that: The housing has a receiving cavity and an opening, and the electrode assembly and the electrolyte are received in the receiving cavity; The cover plate is used to close the opening of the housing.

17. A battery, characterized in that: The battery cell comprises a box body and at least one battery cell according to claim 16, wherein the battery cell is accommodated in the box body.

18. An electrical device, characterized in that: The electric device is configured to receive electric power supplied from the battery according to claim 17 .

19. A method for processing an electrode assembly, characterized in that: include Providing a cathode electrode piece, an anode electrode piece and a separator, wherein the cathode electrode piece includes a cathode current collector and a cathode active material layer coated on the surface of the cathode current collector, and the anode electrode piece includes an anode current collector and an anode active material layer coated on the surface of the anode current collector; Providing a conductive layer, disposing the conductive layer at a predetermined position of the cathode active material layer of the cathode electrode, wherein the cathode active material layer of the cathode electrode includes a covered area covered by the conductive layer, and the conductive layer and the covered area are connected in parallel; The cathode electrode sheet, the anode electrode sheet and the separator are wound, and the cathode electrode sheet, the separator and the anode electrode sheet are wound to form a bending area and a straight area, and the bending area is located on both sides of the straight area. The bending area includes multiple bending parts, and the preset parts are configured so that after winding, at least a part of the conductive layer is located in the bending area on the surface of the cathode active material layer, and each of the conductive layers only covers one of the bending parts.

20. A processing device for an electrode assembly, characterized in that: include Providing an apparatus for providing a cathode electrode piece, an anode electrode piece, a separator, and a conductive layer, wherein the cathode electrode piece includes a cathode current collector and a cathode active material layer coated on the surface of the cathode current collector, and the anode electrode piece includes an anode current collector and an anode active material layer coated on the surface of the anode current collector; a connecting device for connecting the conductive layer to the cathode active material layer of the cathode electrode at a predetermined position of the cathode electrode, the cathode active material layer of the cathode electrode including a covered area covered by the conductive layer, the connecting device for connecting the conductive layer and the covered area in parallel; A winding device is used to wind the cathode electrode sheet, the anode electrode sheet and the separator, wherein the cathode electrode sheet, the separator and the anode electrode sheet are formed into a bending area and a straight area through winding, wherein the bending area is located on both sides of the straight area, and the bending area includes a plurality of bending parts, and the preset part is configured so that after winding, at least a portion of the conductive layer is located in the bending area on the surface of the cathode active material layer, and each of the conductive layers only covers one of the bending parts.

Images