Battery cell, electric equipment and manufacturing method of battery cell

Abstract

The invention provides a battery cell, electric equipment and a manufacturing method of the battery cell. The battery cell comprises a first pole piece, a diaphragm and a second pole piece. The first pole piece comprises a first current collector, a conductive base layer, a first active material layer and an isolation layer. The first current collector comprises first flat sections and first bent sections which are continuously and alternately arranged; a conductive base layer and a first active material layer are arranged on the two sides of each first flat section respectively, and the conductive base layers are arranged between the first flat sections and the first active material layers. The isolation layers are arranged on the two surfaces of each first bending section. And the first pole piece is arranged between the two diaphragms. The diaphragm comprises second flat sections and second bent sections which are continuously and alternately arranged. The second flat section is arranged corresponding to the first flat section. The second bending section is arranged corresponding to the first bending section. And the plurality of second pole pieces are arranged at intervals along the thickness direction of the battery cell. And the second pole pieces and the first flat sections are alternately arranged along the thickness direction of the battery cell. And the second flat section separates the adjacent first pole piece and second pole piece.

Description

Technical Field

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

[0002] Battery cells refer to products that can be used continuously by recharging the active materials after the battery core is discharged. Battery cells are widely used in electrical devices such as mobile phones, laptops, power tools, vehicles, etc. In the development of battery technology, how to ensure the safety of battery cells is one of the research directions in battery technology. Summary of the invention

[0003] In view of the above problems, the present application provides a battery cell, an electrical device and a method for manufacturing the battery cell, which can be beneficial to improving the safety of battery cells.

[0004] The present application provides a battery cell, which includes a first pole piece, a diaphragm and a second pole piece.

[0005] The first pole piece includes a first current collector, a conductive base layer, a first active material layer and an isolation layer. The first current collector includes first flat sections and first bent sections that are continuously and alternately arranged. Each first flat section is arranged at intervals along the thickness direction of the battery cell. Each first bent section connects two adjacent first flat sections. Both surfaces of each first flat section are provided with a conductive base layer and a first active material layer, and along the thickness direction of the first pole piece, the conductive base layer is arranged between the first flat section and the first active material layer. The isolation layer is arranged on both surfaces of each first bent section.

[0006] The first pole piece is arranged between the two diaphragms. The diaphragm includes a second flat section and a second bent section which are arranged continuously and alternately. The second flat section is arranged corresponding to the first flat section. The second bent section is arranged corresponding to the first bent section.

[0007] Along the thickness direction of the battery cell, a plurality of second pole pieces are arranged at intervals. Along the thickness direction of the battery cell, the second pole pieces and the first flat sections are arranged alternately. The second flat sections separate the adjacent first pole pieces and the second pole pieces.

[0008] The battery cell of the embodiment of the present application has a stacked structure. The first pole piece includes a first current collector that extends continuously. A plurality of pole ears are arranged on the first current collector. The first current collector includes a first flat section and a first bent section. A first bent section connects two adjacent first flat sections. A plurality of pole ears are arranged corresponding to a plurality of first flat sections, respectively. When one or more pole ears in the first current collector are broken, each first flat section can still maintain electrical connection with the corresponding electrode terminal, so that it is not easy to destroy the electrochemical balance inside the battery cell, which is beneficial to reduce the possibility of lithium deposition inside the battery cell and ensure the safety of the battery cell. Isolation layers are respectively arranged on the two surfaces of the first bent section. The isolation layer can cover the first bent section so that the inner side and the outer side of the first bent section are in a non-exposed state. The isolation layer can provide protection for the first bent section. For example, when the second bend section of the diaphragm inside the first bend section is cracked or damaged, the second current collector of the second pole piece will not directly contact the first current collector of the first pole piece due to the isolation layer, which is conducive to reducing the possibility of direct contact between the first bend section and the second current collector, resulting in a short circuit between the first current collector and the second current collector and triggering a violent chemical reaction, thereby improving the safety of the battery cell. In addition, the isolation layer can strengthen and support the first bend section, thereby helping to reduce the possibility of collapse, deformation, and wrinkles in the first bend section, resulting in a sharp area in the first bend section, thereby reducing the possibility of the sharp area in the first bend section piercing the diaphragm.

[0009] In one or more of the above optional embodiments, the isolation layer is connected to the conductive base layer.

[0010] The isolation layer is connected to the conductive base layer, which is beneficial to increasing the connection area of ​​the isolation layer, improving the connection stability of the isolation layer, and reducing the possibility of separation of the isolation layer and the first bending section.

[0011] In one or more of the above optional embodiments, the total thickness of the conductive base layer and the first active material layer is greater than the thickness of the isolation layer.

[0012] The thickness of the isolation layer is relatively small, so the isolation layer is relatively easy to bend and deform when subjected to bending moment, reducing the difficulty of bending and deforming the isolation layer, and reducing the possibility of cracks or powdering of the isolation layer due to excessive internal stress in the isolation layer after bending.

[0013] In one or more optional embodiments above, the isolation layer located outside the first bending segment and the second bending segment are in contact with each other, and the isolation layer located inside the first bending segment and the second bending segment are in contact with each other.

[0014] The isolation layer on the outside of the first bending section and the second bending section of the diaphragm contact each other in such a way that the second bending section on the outside can support and limit the first bending section, which helps to reduce the possibility of the first bending section being flattened or wrinkled, resulting in sharp areas in the first bending section or separation of the isolation layer from the first bending section.

[0015] The isolation layer on the inner side of the first bending section and the second bending section of the diaphragm contact each other in such a way that the second bending section on the inner side can support and limit the first bending section, which helps to reduce the possibility of the first bending section being flattened or wrinkled, resulting in sharp areas in the first bending section or separation of the isolation layer from the first bending section.

[0016] In one or more of the above optional embodiments, the material of the isolation layer is the same as that of the conductive base layer, and the isolation layer and the conductive base layer are integrally formed.

[0017] During the processing of the first pole piece, a conductive material coating is provided on the first current collector to simultaneously form a conductive base layer and an isolation layer, which is beneficial to reducing processing steps and improving processing efficiency.

[0018] In one or more of the above optional embodiments, the material of the isolation layer is different from the material of the conductive base layer, and the isolation layer is an insulating material layer.

[0019] During the processing of the first pole piece, a conductive material coating is disposed on the first current collector in an area corresponding to the first flat section to form a conductive base layer, and an insulating material is disposed on the first current collector in an area corresponding to the first bent section to form an isolation layer.

[0020] Since the material of the isolation layer itself is different from that of the first current collector and the isolation layer is an insulating layer, the isolation layer has a better isolation effect on the first bending section. Therefore, when the second current collector of the second pole piece contacts the isolation layer, no chemical reaction will occur between the second current collector and the isolation layer, and thermal runaway of the battery cell will not be caused.

[0021] In one or more of the above optional embodiments, the second pole piece includes a second current collector and a second active material layer. Along the thickness direction of the battery cell, among the two outermost second pole pieces on the battery cell, the second active material layer is arranged on the side of the second current collector facing the second flat section.

[0022] The two outermost second pole pieces are arranged as single-sided second active material layers, which can reduce the usage of the second active material layer, save raw materials, and reduce production costs. At the same time, the thickness of the outermost second pole piece is relatively small, which is conducive to improving the energy density of the battery cell.

[0023] In one or more optional embodiments above, along the thickness direction of the battery cell, of any two adjacent second pole pieces, one is hot-pressed compositely connected to the second flat section of one diaphragm, and the other is hot-pressed compositely connected to the second flat section of another diaphragm.

[0024] In one or more of the above optional embodiments, the width of the first bent section is smaller than the width of the first flat section.

[0025] During the process of folding to form a battery cell, the first bending section is easier to bend than the first flat section, so that the first bending section with a smaller size can guide the first current collector to bend in the first bending section, which is beneficial to improving the accuracy of the bending position of the first current collector, reducing the processing difficulty of folding to form a battery cell, and improving the folding and forming efficiency of the battery cell.

[0026] An embodiment of the present application provides an electrical device, which includes the battery cell of the above embodiment.

[0027] The electrical equipment of the embodiment of the present application includes a battery cell. The first pole piece of the battery cell includes a first current collector extending continuously. A plurality of pole ears are arranged on the first current collector. The first current collector includes a first flat section and a first bent section. A first bent section connects two adjacent first flat sections. A plurality of pole ears are arranged corresponding to the plurality of first flat sections respectively. When one or more pole ears in the first current collector are broken, each first flat section can still maintain electrical connection with the corresponding electrode terminal, so that it is not easy to destroy the electrochemical balance inside the battery cell, which is conducive to reducing the possibility of lithium deposition inside the battery cell and ensuring the safety of the battery cell. Isolation layers are respectively arranged on the two surfaces of the first bent section. The isolation layer can cover the first bent section so that the inner side and the outer side of the first bent section are in a non-exposed state. The isolation layer can form a protection for the first bent section. For example, when cracks or damage appear in the second bending section of the diaphragm inside the first bending section, the second current collector of the second pole piece will not directly contact the first current collector of the first pole piece due to the barrier of the isolation layer, which helps to reduce the possibility of direct contact between the first bending section and the second current collector, resulting in a short circuit between the first current collector and the second current collector and initiating a violent chemical reaction, thereby improving the safety of the battery cell and the safety of electrical equipment using the battery cell.

[0028] The present application provides a method for manufacturing a battery cell, which includes:

[0029] A first pole piece is provided, the first pole piece comprising a first current collector, a conductive base layer, a first active material layer and an isolation layer, the first current collector extends continuously, the first current collector comprises first sections and second sections which are alternately arranged, the conductive base layer and the first active material layer are respectively arranged on both sides of each first section, and the isolation layer is respectively arranged on both sides of each second section;

[0030] Providing a diaphragm, arranging the diaphragms on both sides of the first pole piece respectively, and using a hot pressing composite process to hot press compositely connect the diaphragm and the first pole piece to form a first composite structure;

[0031] Providing a second pole piece, arranging the second pole piece on the first composite structure, arranging the second pole piece corresponding to each first section, and adopting a hot pressing composite process to hot press compositely connect the diaphragm and the second pole piece to form a second composite structure;

[0032] The second composite structure is bent and stacked at each second section to form a battery cell, wherein the first section forms a first flat section, the second section forms a first bent section, the first flat sections are spaced apart along the thickness direction of the battery cell, each first bent section connects two adjacent first flat sections, the diaphragm forms alternately arranged second flat sections and second bent sections, the second flat sections are arranged corresponding to the first flat sections, the second bent sections are arranged corresponding to the first bent sections, the second pole pieces are alternately arranged with the first flat sections, and the second flat sections separate the adjacent first active material layers and second pole pieces.

[0033] In the battery cell manufactured by the manufacturing method of the battery cell of the embodiment of the present application, the first pole piece includes a first current collector extending continuously. A plurality of pole ears are arranged on the first current collector. The first current collector includes a first flat section and a first bent section. A first bent section connects two adjacent first flat sections. A plurality of pole ears are arranged corresponding to the plurality of first flat sections respectively. When one or more pole ears in the first current collector are broken, each first flat section can still maintain electrical connection with the electrode terminal, so that it is not easy to destroy the electrochemical balance inside the battery cell, which is beneficial to reduce the possibility of lithium deposition inside the battery cell and ensure the safety of the battery cell. Isolation layers are respectively arranged on the two surfaces of the first bent section. The isolation layer can cover the first bent section so that the inner side and the outer side of the first bent section are in a non-exposed state. The isolation layer can form a protection for the first bent section. For example, when cracks or damage appear in the second bending section of the diaphragm inside the first bending section, the second current collector of the second pole piece will not directly contact the first current collector of the first pole piece due to the barrier of the isolation layer, which helps to reduce the possibility of direct contact between the first bending section and the second current collector, resulting in a short circuit between the first current collector and the second current collector and initiating a violent chemical reaction.

[0034] In one or more of the above optional embodiments, the method for manufacturing a battery cell includes:

[0035] providing a first current collector;

[0036] Disposing conductive material coatings on two surfaces of the first current collector respectively;

[0037] providing an active material coating on the conductive material coating;

[0038] The active material corresponding to the second section is removed to form a first pole piece, the active material coating corresponding to the first section forms a first active material layer, the conductive material coating corresponding to the first section forms a conductive base layer, and the conductive material coating corresponding to the second section forms an isolation layer.

[0039] After removing the active material corresponding to the second section, a plurality of first active material layers arranged at intervals are formed. The conductive material coating arranged on the first current collector is a continuous layer structure and is not removed. The conductive material coating is arranged on the first current collector to simultaneously form a conductive base layer and an isolation layer, which is conducive to reducing processing steps and improving processing efficiency.

[0040] In one or more of the above optional embodiments, the method for manufacturing a battery cell includes:

[0041] providing a first current collector;

[0042] Disposing conductive material coatings on two surfaces of the first current collector respectively;

[0043] providing an active material coating on the conductive material coating;

[0044] The active material and the conductive material corresponding to the second section are removed, the active material coating corresponding to the first section forms a first active material layer, and the conductive material coating corresponding to the first section forms a conductive base layer;

[0045] An insulating material coating is provided in the second section to form a first pole piece, and the insulating material coating forms an isolation layer.

[0046] The isolation layer is an insulating layer, so the isolation layer has a better isolation effect on the first bending section. Therefore, when the second current collector of the second pole piece contacts the isolation layer, no chemical reaction will occur between the second current collector and the isolation layer, and thermal runaway of the battery cell will not be caused.

[0047] In one or more of the above optional embodiments, the method for manufacturing the battery cell includes: arranging the second composite structure in a vertical direction, gradually lowering the height of the top of the second composite structure, and under the action of gravity, bending and stacking the second composite structure at each second section to form a battery cell.

[0048] Since the second composite structure is relatively easy to bend at each second section, under the action of gravity, the second composite structure is bent and stacked at each second section to form a battery cell, which helps to reduce the processing difficulty of folding to form the battery cell and improve the folding forming efficiency of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0050] Figure 1 is a schematic structural diagram of a battery cell provided by an embodiment of the present application;

[0051] Figure 2 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0052] Figure 3 It is a partial structural schematic diagram of a battery cell provided in one embodiment of the present application;

[0053] Figure 4 yes Figure 3 The enlarged schematic diagram at W in the middle;

[0054] Figure 5 is a schematic diagram of the partial structure of the first current collector and the first electrode tab in an expanded state provided by an embodiment of the present application;

[0055] Figure 6 It is a partial structural schematic diagram of a second current collector and a second electrode tab provided in one embodiment of the present application;

[0056] Figure 7 is a partial structural schematic diagram of a first pole piece in an unfolded state provided by an embodiment of the present application;

[0057] Figure 8 It is a partial structural schematic diagram of a battery cell provided in one embodiment of the present application;

[0058] Fig. 9 It is a partial structural schematic diagram of a battery cell provided in one embodiment of the present application;

[0059] Fig.10 It is a partial structural schematic diagram of a battery cell in an unfolded state provided by an embodiment of the present application;

[0060] Fig.11 It is a partial structural schematic diagram of a battery cell in an unfolded state provided by an embodiment of the present application;

[0061] Fig.12 It is a schematic diagram of a manufacturing process of a battery cell provided in an embodiment of the present application;

[0062] Fig.13 It is a schematic diagram of a manufacturing process of a battery cell provided in an embodiment of the present application;

[0063] Fig.14It is a schematic diagram of a manufacturing process of a battery cell provided in an embodiment of the present application;

[0064] Fig.15 It is a schematic diagram of the manufacturing process of a battery cell provided in one embodiment of the present application.

[0065] Description of reference numerals:

[0066] 10. Battery cells;

[0067] 20. Shell assembly;

[0068] 30. a first electrode terminal;

[0069] 40. a second electrode terminal;

[0070] 50. Battery cells;

[0071] 60. The first pole piece;

[0072] 61. first current collector; 611. first flat section; 612. first bending section; 62. conductive base layer; 63. first active material layer; 64. isolation layer; 65. first pole ear;

[0073] 70, diaphragm; 71, second flat section; 72, second bent section;

[0074] 80. second pole piece; 81. second current collector; 82. second active material layer; 83. second pole ear;

[0075] 100, first paragraph;

[0076] 110, second paragraph;

[0077] 120. A first composite structure;

[0078] 130. A second composite structure;

[0079] 140. Conductive material coating;

[0080] 150. Active material coating;

[0081] 160. Insulation material coating;

[0082] Z, thickness direction. DETAILED DESCRIPTION

[0083] The following embodiments of the technical solution of the present application will be described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0084] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the embodiments of the present application should have the common meanings understood by technicians in the field to which the embodiments of the present application belong.

[0085] In the description of the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the embodiments of the present application.

[0086] In addition, the technical terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0087] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0088] In the related art, a battery cell includes a shell assembly and a battery cell arranged in the shell assembly. The battery cell may be a stacked structure. The battery cell includes a first pole piece, a diaphragm, and a second pole piece that are stacked. The diaphragm is arranged between the first pole piece and the second pole piece. The diaphragm is a porous structure. The diaphragm can be used to transmit ions between the first pole piece and the second pole piece. The diaphragm can isolate the first pole piece and the second pole piece. The first pole piece includes a first current collector and a first active material layer. The material of the first current collector includes a metal material. The second pole piece includes a second current collector and a second active material layer. The material of the second current collector includes a metal material. The first current collector and the second current collector each have good electrical conductivity. The first current collector in the stacked battery cell has an exposed area that is not covered by the first active material layer. When the metal material of the exposed area in the first current collector and the metal material of the second current collector come into direct contact, a short circuit occurs between the first current collector and the second current collector and a violent chemical reaction is triggered, thereby causing thermal runaway of the battery cell and affecting the safety of the battery cell.

[0089] The battery cell of the embodiment of the present application can effectively reduce the possibility of direct contact between the first current collector and the second current collector, so as to improve the safety of the battery cell, thereby helping to improve the safety of the battery monomer using the battery cell.

[0090] Figure 1 The structure of the battery cell 10 is schematically shown. Figure 2 The partial cross-sectional structure of the battery cell 10 is schematically shown. Figure 3 The partial structure of the battery cell 50 is schematically shown. Figure 4 for Figure 3 Enlarged view of center W.

[0091] See also Figures 1 to 4 As shown, an embodiment of the present application provides a battery cell 10. The battery cell 10 includes a shell assembly 20, a first electrode terminal 30, a second electrode terminal 40 and a battery cell 50. The first electrode terminal 30 and the second electrode terminal 40 are disposed in the shell assembly 20. The battery cell 50 is disposed in the shell assembly 20. The first electrode terminal 30 and the second electrode terminal 40 are electrically connected to the negative electrode and the positive electrode of the battery cell 50, respectively.

[0092] The embodiment of the present application provides a battery cell 50, which includes a first pole piece 60, a separator 70 and a second pole piece 80. The first pole piece 60, the separator 70 and the second pole piece 80 are stacked.

[0093] The first pole piece 60 includes a first current collector 61, a conductive base layer 62, a first active material layer 63 and an isolation layer 64. In the battery cell 50, the first current collector 61 is an integrated continuous and uninterrupted overall structure. The first current collector 61 includes first flat sections 611 and first bent sections 612 that are alternately arranged. Each first flat section 611 is arranged at intervals along the thickness direction Z of the battery cell 50. Each first bent section 612 connects two adjacent first flat sections 611. The two surfaces of each first flat section 611 are provided with a conductive base layer 62 and a first active material layer 63, and along the thickness direction of the first pole piece 60, the conductive base layer 62 is arranged between the first flat section 611 and the first active material layer 63. Isolation layers 64 are respectively arranged on the two surfaces of each first bent section 612.

[0094] The first pole piece 60 is disposed between two diaphragms 70. In the battery cell 50, each diaphragm 70 is an integral and uninterrupted structure. The diaphragm 70 includes a second flat section 71 and a second bent section 72 that are continuously and alternately disposed. The second flat section 71 is disposed corresponding to the first flat section 611. The second bent section 72 is disposed corresponding to the first bent section 612.

[0095] Along the thickness direction Z of the battery cell 50, a plurality of second pole sheets 80 are arranged at intervals. In the battery cell 50, the plurality of second pole sheets 80 are independently arranged structures, and any two second pole sheets 80 are not connected. Along the thickness direction Z of the battery cell 50, the second pole sheets 80 and the first flat sections 611 are arranged alternately. The second flat sections 71 separate the adjacent first active material layers 63 and the second pole sheets 80.

[0096] In the embodiment of the present application, the first current collector 61 may be a metal sheet. The thickness of the first current collector 61 may range from 3 microns (μm) to 20 microns. The material of the conductive base layer 62 may include conductive glue or conductive nano. The conductive base layer 62 has high viscosity and conductivity. The thickness of the conductive base layer 62 ranges from 1 micron to 20 microns. The material of the diaphragm 70 may include, but is not limited to, polyethylene or glass fiber. The second pole piece 80 may include a second current collector 81 and a second active material layer 82. The second current collector 81 may be a metal sheet.

[0097] In some possible implementations, see Figure 3 and Figure 4 As shown, the first pole piece 60 can be used as a negative pole piece. The material of the first current collector 61 can include copper or copper alloy. The material of the first active material layer 63 can include, but is not limited to, graphite or silicon-based materials. The second pole piece 80 can be used as a positive pole piece. The material of the second current collector 81 can include aluminum or aluminum alloy. The second active material layer 82 includes a positive active material containing lithium.

[0098] In other achievable embodiments, the first pole piece 60 may be used as a positive pole piece. The material of the first current collector 61 may include aluminum or an aluminum alloy. The first active material layer 63 includes a positive active material containing lithium. The second pole piece 80 may be used as a negative pole piece. The material of the second current collector 81 may include copper or a copper alloy. The material of the second active material layer 82 may include, but is not limited to, graphite or a silicon-based material.

[0099] Figure 5 The partial structure of the first current collector 61 and the first electrode tab 65 in the unfolded state is schematically shown. Figure 4 and Figure 5 As shown, in the first electrode sheet 60, a plurality of first electrode tabs 65 may be disposed on the first current collector 61. The number of the first electrode tabs 65 may be arranged one-to-one corresponding to the number of the first flat sections 611. The plurality of first electrode tabs 65 may be stacked and welded to the first electrode terminal 30 by an ultrasonic welding process. Figure 6 The partial structure of the second current collector 81 and the second electrode tab 83 is schematically shown. Figure 4 and Figure 6As shown, in the second pole piece 80, one second current collector 81 may be provided with one second pole tab 83. A plurality of second pole tabs 83 may be stacked and welded to the second electrode terminal 40 by an ultrasonic welding process. In some examples, a laser forming process is used to remove part of the material on the first current collector 61 to form the first pole tab 65. A laser forming process is used to remove part of the material on the second current collector 81 to form the second pole tab 83.

[0100] If the first pole piece 60 only includes a plurality of independently arranged first flat sections 611, the first flat sections 611 are connected in parallel with each other. A plurality of first pole tabs 65 are respectively connected to a plurality of first flat sections 611. When one of the first pole tabs 65 or a plurality of first pole tabs 65 is broken, the corresponding first flat section 611 fails, so that the corresponding first flat section 611 is electrically disconnected from the first electrode terminal 30, thereby destroying the electrochemical balance inside the battery cell 50, so that the battery cell 50 is likely to have lithium deposition. In order to reduce the possibility of the pole tab breaking, one way is to use a thicker substrate to form the first flat section 611 and the first pole tab 65. However, using a thicker substrate will reduce the energy density of the battery cell 50.

[0101] In the embodiment of the present application, the first current collector 61 is a continuous extension structure, and a plurality of tabs are arranged on the first current collector 61. When one of the first tabs 65 or a plurality of the first tabs 65 are broken, each first flat section 611 can still maintain electrical connection with the first electrode terminal 30, so that it is not easy to destroy the electrochemical balance inside the battery cell 50, which is conducive to reducing the possibility of the above-mentioned problem. At the same time, in the embodiment of the present application, a substrate with a relatively small thickness can be used to process and form the first current collector 61, which is conducive to improving the energy density of the battery cell 50.

[0102] If the first active material layer 63 is provided on the first bending section 612, when the first bending section 612 is bent, the first bending section 612 will synchronously drive the first active material layer 63 to bend. Since the flexibility of the first active material layer 63 is relatively poor, during the bending process of the first active material layer 63, the first active material layer 63 is likely to break and fall off under the action of its own internal stress. The active material that falls off from the first bending section 612 is likely to connect the first pole piece 60 and the second pole piece 80 and cause the first pole piece 60 and the second pole piece 80 to short-circuit, affecting the safety of the battery cell 50. In the embodiment of the present application, a conductive base layer 62 is provided on the first flat section 611 of the first current collector 61. The first active material layer 63 is provided on the conductive base layer 62. The first active material layer 63 is not provided on the first bending section 612 of the first current collector 61, so it can help reduce the possibility of the above-mentioned problems.

[0103] The first bending section 612 has an outer side and an inner side. The outer side of the first bending section 612 is the surface facing away from the second pole piece 80. The inner side of the first bending section 612 is the surface facing the second pole piece 80. The outer side and the inner side of the first bending section 612 are respectively provided with an isolation layer 64, so that the outer side and the inner side of the first bending section 612 are in a non-exposed state. Therefore, the isolation layer 64 can isolate the first bending section 612. The isolation layer 64 is located between the first bending section 612 of the first current collector 61 and the second bending section 72 of the diaphragm 70.

[0104] The battery cell 50 of the embodiment of the present application is a stacked structure. The first pole piece 60 includes a first current collector 61 that extends continuously. A plurality of pole ears are arranged on the first current collector 61. The first current collector 61 includes a first flat section 611 and a first bent section 612. A first bent section 612 connects two adjacent first flat sections 611. The plurality of pole ears are arranged corresponding to the plurality of first flat sections 611. When one first pole ear 65 or a plurality of first pole ears 65 in the first current collector 61 is broken, each first flat section 611 can still maintain electrical connection with the first electrode terminal 30, so that it is not easy to destroy the electrochemical balance inside the battery cell 50, which is conducive to reducing the possibility of lithium deposition inside the battery cell 50 and ensuring the safety of the battery cell 50. Isolation layers 64 are respectively arranged on the two surfaces of the first bent section 612. The isolation layer 64 can cover the first bent section 612, so that the inner side and the outer side of the first bent section 612 are in a non-exposed state. The isolation layer 64 can form a protection for the first bent section 612. For example, when the second bending section 72 of the diaphragm 70 inside the first bending section 612 is cracked or damaged, the second current collector 81 of the second pole piece 80 will not directly contact the first current collector 61 of the first pole piece 60 due to the isolation layer 64, which is conducive to reducing the possibility of direct contact between the first bending section 612 and the second current collector 81, resulting in a short circuit between the first current collector 61 and the second current collector 81 and inducing a violent chemical reaction, thereby improving the safety of the battery cell 50. In addition, the isolation layer 64 can strengthen and support the first bending section 612, thereby helping to reduce the possibility of the first bending section 612 collapsing, deforming, and wrinkling, resulting in a sharp area in the first bending section 612, thereby reducing the possibility of the sharp area of ​​the first bending section 612 piercing the diaphragm 70.

[0105] In some possible implementations, see Figure 5 As shown, the width K of the first bending segment 612 in the unfolded state is 0.1 micrometer to 1 micrometer.

[0106] In some examples, the first electrode sheet 60 can be used as a negative electrode sheet. The second electrode sheet 80 can be used as a positive electrode sheet. Along the thickness direction Z of the battery cell 50, the orthographic projection area of ​​the second electrode sheet 80 is smaller than the orthographic projection area of ​​the first active material layer 63, which is conducive to reducing the possibility of lithium plating.

[0107] In some examples, the first electrode sheet 60 can be used as a positive electrode sheet. The second electrode sheet 80 can be used as a negative electrode sheet. Along the thickness direction Z of the battery cell 50, the orthographic projection area of ​​the second electrode sheet 80 is larger than the orthographic projection area of ​​the first active material layer 63, which is conducive to reducing the possibility of lithium deposition.

[0108] In some achievable ways, Figure 7 The partial structure of the first pole piece 60 in the unfolded state is schematically shown. Figure 4 and Figure 7 As shown, the isolation layer 64 is connected to the conductive base layer 62, which is beneficial to increase the connection area of ​​the isolation layer 64, improve the connection stability of the isolation layer 64, and reduce the possibility of separation of the isolation layer 64 and the first bending section 612. The two isolation layers 64 can cover the outer side surface and the inner side surface of the first bending section 612 respectively, so as to effectively isolate the outer side surface and the inner side surface of the first bending section 612.

[0109] In some achievable embodiments, the total thickness of the conductive base layer 62 and the first active material layer 63 is greater than the thickness of the isolation layer 64. The thickness of the isolation layer 64 is relatively small, so that the isolation layer 64 is relatively easy to bend and deform when subjected to a bending moment, thereby reducing the difficulty of bending and deforming the isolation layer 64, and reducing the possibility of cracks or powdering of the isolation layer 64 due to excessive internal stress of the isolation layer 64 after bending.

[0110] In some achievable ways, Figure 8 The partial structure of the battery cell 50 is schematically shown. Figure 8 As shown, the isolation layer 64 and the second bending segment 72 located outside the first bending segment 612 are in contact with each other. The isolation layer 64 and the second bending segment 72 located inside the first bending segment 612 are in contact with each other.

[0111] The isolation layer 64 on the outside of the first bending section 612 and the second bending section 72 of the diaphragm 70 are in contact with each other in such a way that the second bending section 72 on the outside can support and limit the first bending section 612, thereby reducing the possibility of the first bending section 612 being flattened or wrinkled, resulting in sharp areas in the first bending section 612, or causing the isolation layer 64 to separate from the first bending section 612.

[0112] The isolation layer 64 on the inner side of the first bending section 612 and the second bending section 72 of the diaphragm 70 are in contact with each other so that the second bending section 72 on the inner side can support and limit the first bending section 612, which helps to reduce the possibility of the first bending section 612 being flattened or wrinkled, resulting in sharp areas in the first bending section 612, or causing the isolation layer 64 to separate from the first bending section 612.

[0113] In some examples, the isolation layer 64 and the second bending segment 72 located outside the first bending segment 612 are connected to each other. The isolation layer 64 and the second bending segment 72 located inside the first bending segment 612 are connected to each other.

[0114] In some possible implementations, see Figure 8 As shown, the material of the isolation layer 64 is the same as that of the conductive base layer 62. The isolation layer 64 and the conductive base layer 62 are integrally formed.

[0115] During the processing of the first pole piece 60 , a conductive material coating 140 is provided on the first current collector 61 to simultaneously form a conductive base layer 62 and an isolation layer 64 , which is beneficial to reducing the processing steps and improving the processing efficiency.

[0116] Since the material of the isolation layer 64 is different from that of the first current collector 61, when the second current collector 81 of the second pole piece 80 contacts the isolation layer 64, a violent chemical reaction is not likely to occur between the second current collector 81 and the isolation layer 64, which is beneficial to reduce the possibility of thermal runaway of the battery cell 50. When the second current collector 81 contacts the isolation layer 64, the intensity of the chemical reaction between the second current collector 81 and the isolation layer 64 is lower than the intensity of the chemical reaction between the first current collector 61 and the second current collector 81 in direct contact.

[0117] In some examples, the material of the conductive base layer 62 and the material of the isolation layer 64 may include, but are not limited to, conductive glue or conductive nanoparticles.

[0118] In some achievable ways, Fig. 9 The partial structure of the battery cell 50 is schematically shown. Fig. 9 As shown, the material of the isolation layer 64 is different from the material of the conductive base layer 62. The isolation layer 64 is an insulating material layer.

[0119] During the processing of the first pole piece 60 , a conductive material coating 140 is disposed on the first current collector 61 in an area corresponding to the first flat section 611 to form a conductive base layer 62 , and an insulating material is disposed on the first current collector 61 in an area corresponding to the first bent section 612 to form an isolation layer 64 .

[0120] Since the material of the isolation layer 64 itself is different from the material of the first current collector 61, and the isolation layer 64 is an insulating layer, the isolation layer 64 has a better isolation effect on the first bending section 612. Therefore, when the second current collector 81 of the second pole piece 80 contacts the isolation layer 64, a chemical reaction will not occur between the second current collector 81 and the isolation layer 64, and thermal runaway of the battery cell 50 will not be caused.

[0121] In some examples, the material of the isolation layer 64 includes plastic. For example, the material of the isolation layer 64 may include, but is not limited to, polyethylene and polypropylene.

[0122] In some possible implementations, see Fig. 9 As shown, the second pole piece 80 includes a second current collector 81 and a second active material layer 82. Along the thickness direction Z of the battery cell 50, the outermost side of the battery cell 50 is the second pole piece 80. Among the two outermost second pole pieces 80 on the battery cell 50, the second active material layer 82 is arranged on the side of the second current collector 81 facing the second flat section 71. The two outermost second pole pieces 80 are pole pieces with the second active material layer 82 arranged on one side, and the remaining second pole pieces 80 are pole pieces with the second active material layer 82 arranged on both sides.

[0123] The two outermost second pole pieces 80 are provided with a single-sided second active material layer 82, which can reduce the usage of the second active material layer 82, save raw materials, and reduce production costs. At the same time, the thickness of the outermost second pole piece 80 is relatively small, which is conducive to improving the energy density of the battery cell 50.

[0124] In some examples, the first electrode sheet 60 can be used as a negative electrode sheet. The second electrode sheet 80 can be used as a positive electrode sheet. If the two outermost second electrode sheets 80 are set as double-sided second active material layers 82, the second active material layer 82 on the second electrode sheet 80 facing away from the second flat section 71 will have lithium deposition problems, affecting the safety of the battery cell 50. In the embodiment of the present application, the two outermost second electrode sheets 80 are set as single-sided second active material layers 82, which can help solve the above problems.

[0125] In some possible implementations, see Figure 3 and Fig. 9 As shown, along the thickness direction Z of the battery cell 50, one of any two adjacent second pole pieces 80 is thermocompressively composite-connected to the second flat section 71 of one diaphragm 70, and the other is thermocompressively composite-connected to the second flat section 71 of another diaphragm 70. Any two adjacent second pole pieces 80 are respectively connected to different diaphragms 70.

[0126] Fig.10 The partial structure of the battery cell 50 in the unfolded state is schematically shown. Fig. 9 and Fig.10As shown, when the battery cell 50 is in the unfolded state, N first flat sections 611 are arranged at intervals, and N is an integer greater than or equal to 2. A first bending section 612 is arranged between two adjacent first flat sections 611. The second flat sections 71 on one side of the 1st to N-1th first flat sections 611 are connected to the second pole piece 80, that is, the 1st to N-1th first flat sections 611 are respectively provided with a second pole piece 80. Among the second pole pieces 80 corresponding to the 1st to N-1th first flat sections 611, one of any two adjacent second pole pieces 80 is on one side of the first current collector 61, and the other is on the other side of the first current collector 61. The second pole pieces 80 are respectively connected to the second flat sections 71 on both sides of the Nth first flat section 611, that is, two second pole pieces 80 are correspondingly provided to the Nth first flat section 611.

[0127] Exemplarily, the first current collector 61 includes 7 first flat sections 611 and 6 first bent sections 612. When the battery cell 50 is in the unfolded state, each of the first to sixth first flat sections 611 is provided with a corresponding second pole piece 80. Among the second pole pieces 80 provided corresponding to the first to sixth first flat sections 611, one of any two adjacent second pole pieces 80 is on one side of the first current collector 61, and the other is on the other side of the first current collector 61. Two second pole pieces 80 are provided corresponding to the seventh first flat section 611.

[0128] In some achievable ways, Fig.11 The partial structure of the battery cell 50 in the unfolded state is schematically shown. Fig.11 As shown, along the bending axis of the first bending section 612, the width L1 of the first bending section 612 is less than the width L2 of the first flat section 611. In the process of folding to form the battery cell 50, the first bending section 612 can be bent along the bending axis. When the first current collector 61 is unfolded, the extension direction of the bending axis of the first bending section 612 is the same as the width direction of the first current collector 61.

[0129] During the process of folding to form the battery cell 50, the first bending section 612 is easier to bend than the first flat section 611, so that the first bending section 612 with a smaller width can guide the first current collector 61 to bend in the first bending section 612, which is beneficial to improve the accuracy of the bending position of the first current collector 61, reduce the processing difficulty of folding to form the battery cell 50, and improve the folding forming efficiency of the battery cell 50.

[0130] In some examples, a laser cutting process may be used to remove a portion of the material of the first current collector 61 at a position corresponding to the first bending section 612 , so that the width L1 of the first bending section 612 is smaller than the width L2 of the first flat section 611 .

[0131] According to some embodiments of the present application, an electric device is provided, including a battery cell 50 of any of the above solutions, and the battery cell 50 is used to provide electric energy for the electric device. The electric device may include, for example, a mobile phone, a laptop computer, a power tool, a vehicle, etc.

[0132] Fig.12 The manufacturing process of the battery cell 50 is schematically shown. Fig.12 As shown, the embodiment of the present application also provides a method for manufacturing a battery cell 50, which includes:

[0133] A first pole piece 60 is provided. The first pole piece 60 includes a first current collector 61, a conductive base layer 62, a first active material layer 63 and an isolation layer 64. The first current collector 61 extends continuously. The first current collector 61 includes first segments 100 and second segments 110 that are alternately arranged. The conductive base layer 62 and the first active material layer 63 are respectively arranged on both sides of each first segment 100. The isolation layer 64 is respectively arranged on both sides of each second segment 110.

[0134] Providing a diaphragm 70, arranging the diaphragms 70 on both sides of the first pole piece 60, and using a hot pressing composite process to hot press composite the diaphragm 70 and the first pole piece 60 to form a first composite structure 120;

[0135] Providing a second pole piece 80, setting the second pole piece 80 on the first composite structure 120, and setting the second pole piece 80 corresponding to each first section 100, and using a hot pressing composite process to hot press compositely connect the diaphragm 70 and the second pole piece 80 to form a second composite structure 130;

[0136] The second composite structure 130 is bent and stacked at each second section 110 to form a battery cell 50, wherein the first section 100 forms a first flat section 611, and the second section 110 forms a first bent section 612, and each first flat section 611 is arranged at intervals along the thickness direction Z of the battery cell 50, and each first bent section 612 connects two adjacent first flat sections 611, and the diaphragm 70 forms alternating second flat sections 71 and second bent sections 72, the second flat section 71 is arranged corresponding to the first flat section 611, and the second bent section 72 is arranged corresponding to the first bent section 612, and the second electrode sheet 80 is arranged alternately with the first flat section 611, and the second flat section 71 separates the adjacent first active material layer 63 and the second electrode sheet 80.

[0137] In some achievable ways, Fig.13 The manufacturing process of the battery cell 50 is schematically shown. Fig.13As shown, the second composite structure 130 is arranged in the vertical direction, and then the height of the top of the second composite structure 130 is gradually lowered. Since the second composite structure 130 is relatively easy to bend at each second section 110, under the action of gravity, the second composite structure 130 is bent and stacked at each second section 110 to form the battery cell 50, which is conducive to reducing the processing difficulty of folding to form the battery cell 50 and improving the folding forming efficiency of the battery cell 50.

[0138] In some achievable ways, Fig.14 The manufacturing process of the battery cell 50 is schematically shown. Fig.14 As shown, the manufacturing method of the battery cell 50 includes:

[0139] Providing a first current collector 61;

[0140] Conductive material coatings 140 are respectively provided on two surfaces of the first current collector 61;

[0141] Disposing an active material coating 150 on the conductive material coating 140;

[0142] The active material corresponding to the second section 110 is removed to form the first pole piece 60 , the active material coating 150 arranged corresponding to the first section 100 forms a first active material layer 63 , the conductive material coating 140 arranged corresponding to the first section 100 forms a conductive base layer 62 , and the conductive material coating 140 arranged corresponding to the second section 110 forms an isolation layer 64 .

[0143] After removing the active material corresponding to the second section 110, a plurality of first active material layers 63 are formed. The conductive material coating 140 disposed on the first current collector 61 is a continuous layer structure and is not removed. The conductive material coating 140 is disposed on the first current collector 61 to simultaneously form the conductive base layer 62 and the isolation layer 64, which is conducive to reducing the processing steps and improving the processing efficiency.

[0144] In some examples, a laser cleaning process is used to remove the active material corresponding to the second segment 110 .

[0145] In some achievable ways, Fig.15 The manufacturing process of the battery cell 50 is schematically shown. Fig.15 As shown, the manufacturing method of the battery cell 50 includes:

[0146] Providing a first current collector 61;

[0147] Conductive material coatings 140 are respectively provided on two surfaces of the first current collector 61;

[0148] Disposing an active material coating 150 on the conductive material coating 140;

[0149] The active material and the conductive material corresponding to the second section 110 are removed, the active material coating 150 corresponding to the first section 100 forms the first active material layer 63, and the conductive material coating 140 corresponding to the first section 100 forms the conductive base layer 62;

[0150] An insulating material coating 160 is disposed on the second section 110 to form the first pole piece 60 , and the insulating material coating 160 forms a separation layer 64 .

[0151] After removing the active material corresponding to the second section 110, a plurality of first active material layers 63 are formed which are spaced apart from each other. After removing the conductive material corresponding to the second section 110, a plurality of conductive base layers 62 are formed which are spaced apart from each other.

[0152] The isolation layer 64 is an insulating layer, so the isolation layer 64 has a good isolation effect on the first bending section 612. Therefore, when the second current collector 81 of the second pole piece 80 contacts the isolation layer 64, no chemical reaction will occur between the second current collector 81 and the isolation layer 64, and thermal runaway of the battery cell 50 will not be caused.

[0153] In some examples, a laser cleaning process is used to remove the active material and the conductive material corresponding to the second segment 110 .

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: A first pole piece, comprising a first current collector, a conductive base layer, a first active material layer and an isolation layer, wherein the first current collector comprises first flat segments and first bent segments which are continuously and alternately arranged, wherein each of the first flat segments is arranged at intervals along the thickness direction of the battery cell, wherein each of the first bent segments connects two adjacent first flat segments, wherein both surfaces of each of the first flat segments are provided with the conductive base layer and the first active material layer, wherein along the thickness direction of the first pole piece, the conductive base layer is arranged between the first flat segment and the first active material layer, and the isolation layer is arranged on both surfaces of each of the first bent segments; A diaphragm, wherein the first pole piece is arranged between two layers of the diaphragms, and the diaphragm comprises a second flat section and a second bent section which are arranged continuously and alternately, wherein the second flat section is arranged corresponding to the first flat section, and the second bent section is arranged corresponding to the first bent section; A plurality of second pole pieces are arranged at intervals along the thickness direction of the battery core, the second pole pieces are arranged alternately with the first flat sections, and the second flat sections separate adjacent first pole pieces and second pole pieces.

2. The battery cell according to claim 1, characterized in that: The isolation layer is connected to the conductive base layer.

3. The battery cell according to claim 1, characterized in that: The total thickness of the conductive base layer and the first active material layer is greater than the thickness of the isolation layer.

4. The battery cell according to claim 1, characterized in that: The isolation layer located outside the first bending section and the second bending section are in contact with each other, and the isolation layer located inside the first bending section and the second bending section are in contact with each other.

5. The battery cell according to claim 1, characterized in that: The material of the isolation layer is the same as that of the conductive base layer, and the isolation layer and the conductive base layer are integrally formed.

6. The battery cell according to claim 1, characterized in that: The material of the isolation layer is different from that of the conductive base layer, and the isolation layer is an insulating material layer.

7. The battery cell according to claim 1, characterized in that: The second pole piece includes a second current collector and a second active material layer. Along the thickness direction of the battery cell, the second active material layer is arranged on the side of the second current collector facing the second flat section in the two outermost second pole pieces on the battery cell.

8. The battery cell according to claim 1, characterized in that: Along the thickness direction of the battery core, one of any two adjacent second pole pieces is connected to the second flat section of one diaphragm by hot pressing and composite connection, and the other is connected to the second flat section of another diaphragm by hot pressing and composite connection.

9. The battery cell according to claim 1, characterized in that: The width of the first bending section is smaller than the width of the first flat section.

10. An electrical device, characterized in that: Comprising the battery cell as claimed in any one of claims 1 to 9.

11. A method for manufacturing a battery cell, characterized in that: include: Providing a first pole piece, the first pole piece comprising a first current collector, a conductive base layer, a first active material layer and an isolation layer, the first current collector extending continuously, the first current collector comprising first segments and second segments arranged alternately, the conductive base layer and the first active material layer being arranged on both sides of each first segment, and the isolation layer being arranged on both sides of each second segment; Providing a diaphragm, arranging the diaphragm on both sides of the first pole piece respectively, and using a hot pressing composite process to hot press compositely connect the diaphragm and the first pole piece to form a first composite structure; Providing a second pole piece, arranging the second pole piece on the first composite structure, arranging the second pole piece corresponding to each first segment, and using a hot pressing composite process to hot press compositely connect the diaphragm and the second pole piece to form a second composite structure; The second composite structure is bent and stacked at each of the second sections to form a battery cell, wherein the first section forms a first flat section, the second section forms a first bent section, the first flat sections are spaced apart along the thickness direction of the battery cell, each first bent section connects two adjacent first flat sections, the diaphragm forms alternating second flat sections and second bent sections, the second flat section is arranged corresponding to the first flat section, the second bent section is arranged corresponding to the first bent section, the second pole pieces are alternately arranged with the first flat sections, and the second flat sections separate the adjacent first active material layers and the second pole pieces.

12. The method for manufacturing a battery cell according to claim 11, characterized in that: providing the first current collector; Disposing conductive material coatings on two surfaces of the first current collector respectively; providing an active material coating on the conductive material coating; The active material corresponding to the second segment is removed to form the first pole piece, the active material coating corresponding to the first segment forms the first active material layer, the conductive material coating corresponding to the first segment forms the conductive base layer, and the conductive material coating corresponding to the second segment forms the isolation layer.

13. The method for manufacturing a battery cell according to claim 11, characterized in that: providing the first current collector; Disposing conductive material coatings on two surfaces of the first current collector respectively; providing an active material coating on the conductive material coating; removing the active material and the conductive material corresponding to the second section, so that the active material coating corresponding to the first section forms the first active material layer, and the conductive material coating corresponding to the first section forms the conductive base layer; An insulating material coating is provided on the second section to form the first pole piece, and the insulating material coating forms the isolation layer.

14. The method for manufacturing a battery cell according to claim 11, characterized in that: The second composite structure is arranged in a vertical direction, and the height of the top of the second composite structure is gradually lowered. Under the action of gravity, the second composite structure is bent and stacked at each of the second sections to form the battery core.

Images