Electrode assembly, battery cell, battery device, and electric device
By providing a barrier layer in the battery cell, the barrier layer is electrically connected to the positive electrode sheet, the problem of lithium evolution phenomenon is solved, and the safety and stability of the battery are improved.
Patent Information
- Application Number
- CN202422226277.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2025-08-22
- Estimated Expiration
- 2034-09-11
AI Technical Summary
How to reduce the lithium-ion phenomenon of battery cells to improve the safety performance of the battery.
A barrier layer is provided between the positive electrode sheet and the negative electrode sheet. The barrier layer includes at least a conductive part and is electrically connected to the positive electrode main body part to prevent the ions of the positive electrode active material from being embedded in the bending area of the negative electrode sheet, ensuring that the barrier layer and the positive electrode sheet have equal potential, and prevent lithium ions from being driven out of potential.
It effectively reduces the lithium evolution phenomenon of battery cells, improves the safety performance of the battery, and reduces the risk of short circuits, while not affecting the electrochemical performance and capacity of the battery.
Smart Images
Figure CN223260805U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of battery technology, and in particular to an electrode assembly, a battery cell, a battery device, and an electrical device. Background Art
[0002] In recent years, with the rapid development of new energy technologies, new energy vehicles have become increasingly popular, gradually replacing traditional fuel vehicles and becoming one of the mainstream modes of transportation. As the power source of new energy vehicles, power batteries are one of their core components, making their safety performance a key concern.
[0003] In the development of battery technology, how to reduce the lithium plating phenomenon of battery cells is a research direction in battery technology. Utility Model Content
[0004] The embodiments of the present application provide an electrode assembly, a battery cell, a battery device, and an electrical device, which can reduce the lithium plating phenomenon of the battery cell.
[0005] In the first aspect, an embodiment of the present application provides a battery cell, which includes a shell and an electrode assembly arranged in the shell, the electrode assembly including a positive electrode sheet, a negative electrode sheet and a barrier layer, the positive electrode sheet includes a positive electrode main body and a positive electrode active material layer arranged on the positive electrode main body; the negative electrode sheet, the positive electrode sheet and the negative electrode sheet are wound to form a bending area; the barrier layer is located in the bending area, the barrier layer is arranged on the side of the positive electrode sheet facing the negative electrode sheet, and the barrier layer includes at least a conductive part, which is electrically connected to the positive electrode main body.
[0006] In the above solution, by providing a barrier layer between the positive and negative electrode sheets, the barrier layer can prevent ions released from the positive electrode active material from being embedded in the bend area of the negative electrode sheet, thereby reducing lithium plating. Furthermore, the barrier layer includes at least a conductive portion. By electrically connecting the conductive portion of the barrier layer to the main body of the positive electrode, the barrier layer and the positive electrode sheet can be brought to the same potential. Since the lithium ions of the positive electrode active material in the bend area are not driven by an electric potential, they cannot be released, further reducing lithium plating in the battery cell.
[0007] In some embodiments, the resistivity of the conductive portion is ρ1, and ρ1 satisfies: ρ1<5×10 -8 Ω·m.
[0008] In the above solution, the conductive part has a low resistivity and good conductivity, which can ensure to a certain extent that there is no potential difference between the barrier layer and the positive electrode sheet.
[0009] In some embodiments, ρ1 satisfies: ρ1≤2.8×10 -8 Ω·m.
[0010] In the above solution, the conductive performance of the conductive part is further improved.
[0011] In some embodiments, the barrier layer further includes an insulating portion, which is disposed on a side of the conductive portion facing the negative electrode plate.
[0012] In the above solution, the insulating portion can, to a certain extent, prevent the positive electrode sheet and the negative electrode sheet in the bending area from contacting each other, thereby preventing the occurrence of a short circuit.
[0013] In some embodiments, the resistivity of the insulating portion is ρ2, and ρ2 satisfies: ρ2>10 14 Ω·cm.
[0014] In the above solution, the resistivity of the insulating portion is relatively large and the insulation performance is good, thereby improving the insulation effect between the positive electrode sheet and the negative electrode sheet in the bending area.
[0015] In some embodiments, ρ2 satisfies: 10 15 Ω·cm≤ρ2≤10 19 Ω·cm.
[0016] In the above solution, the insulation performance of the insulating portion is further improved.
[0017] In some embodiments, the thicknesses of the conductive portion and the insulating portion are L1 and L2, respectively, and the resistivities of the conductive portion and the insulating portion are ρ1 and ρ2, respectively, wherein (ρ1×L1+ρ2×L2) / (L1+L2)>10 14 Ω·cm.
[0018] In the above solution, by adjusting the thickness and resistivity of the conductive portion and the insulating portion respectively, the resistivity range of the entire barrier layer is limited, thereby ensuring the insulation effect of the entire barrier layer to a certain extent.
[0019] In some embodiments, 10 15 Ω·cm≤(ρ1×L1+ρ2×L2) / (L1+L2)≤10 19 Ω·cm.
[0020] In the above solution, the insulating effect of the entire barrier layer is further improved by further limiting the resistivity of the entire barrier layer.
[0021] In some embodiments, the barrier layer has a thickness D, where D satisfies: 2 μm ≤ D ≤ 500 μm.
[0022] In the above solution, the thickness of the barrier layer is within a moderate range, which can ensure the effect of reducing lithium plating to a certain extent, while not occupying too much space in the electrode assembly, thereby reducing the impact on the capacity of the battery cell.
[0023] In some embodiments, D satisfies: 5 μm≤D≤20 μm.
[0024] In the above solution, by further limiting the thickness range of the barrier layer, the effect of lithium plating is further guaranteed, and the impact on the capacity of the battery cell is reduced.
[0025] In some embodiments, the conductive portion is welded to the positive electrode main body.
[0026] In the above solution, the conductive part is electrically connected to the positive electrode main body by welding, without introducing other substances, thereby reducing the impact on the electrochemical performance of the electrode assembly.
[0027] In some embodiments, both ends of the positive electrode body along the width direction of the positive electrode sheet are protruded relative to the positive electrode active material layer to form protrusions; and the opposite ends of the barrier layer along the width direction are respectively welded to the protrusions.
[0028] In the above solution, by welding the two ends of the barrier layer in the width direction to the protruding portions of the positive electrode main body, the connection stability between the barrier layer and the positive electrode main body can be improved.
[0029] In some embodiments, the area of the electrode assembly close to the winding center is the inner circle area, the area away from the winding center is the outer circle area, and the barrier layer is located in the inner circle area.
[0030] In the above solution, by arranging the barrier layer in the inner circle area, the space occupied by the electrode assembly can be reduced, thereby reducing the impact on the capacity of the battery cell.
[0031] In some embodiments, the barrier layer is disposed at the innermost position of the inner circle region.
[0032] In the above solution, by arranging the barrier layer at the innermost position where lithium deposition is most likely to occur, the impact on the capacity of the battery cell is further reduced.
[0033] In the second aspect, an embodiment of the present application also provides an electrode assembly, including a positive electrode sheet, a negative electrode sheet and a barrier layer, the positive electrode sheet includes a positive electrode main body and a positive electrode active material layer arranged on the positive electrode main body; the negative electrode sheet, the positive electrode sheet and the negative electrode sheet are wound to form a bending area; the barrier layer is located in the bending area, the barrier layer is arranged on the concave surface of the positive electrode sheet, facing the negative electrode sheet, the barrier layer includes at least a conductive part, and the conductive part is electrically connected to the positive electrode main body.
[0034] In a third aspect, an embodiment of the present application further provides a battery device comprising a battery cell according to any of the above embodiments.
[0035] In a fourth aspect, an embodiment of the present application further provides an electrical device, comprising the above-mentioned battery device, which is used to provide electrical energy.
[0036] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0038] Figure 1 A schematic structural diagram of a vehicle according to some embodiments of the present application;
[0039] Figure 2 An exploded view of a battery device according to some embodiments of the present application;
[0040] Figure 3 This is a schematic structural diagram of a battery module according to some embodiments of the present application;
[0041] Figure 4 This is a schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application;
[0042] Figure 5 is a schematic structural diagram of a bending region of an electrode assembly in some embodiments of the present application;
[0043] Figure 6 is a schematic structural diagram of an electrode assembly in some embodiments of the present application;
[0044] Figure 7 is a schematic structural diagram of a barrier layer in some embodiments of the present application;
[0045] Figure 8 Schematic diagram of the connection between the barrier layer and the positive electrode sheet in some embodiments of the present application;
[0046] Figure 9 This is a schematic diagram of the connection between the barrier layer and the positive electrode plate at another angle in some embodiments of the present application.
[0047] Description of reference numerals:
[0048] 1000, vehicle; 100, battery device; 200, controller; 300, motor; 10, upper cover; 30, housing; 400, battery module; 20, battery cell; 22, housing; 21, end cap; 23, electrode assembly; 40, positive electrode plate; 41, positive electrode body; 411, protrusion; 42, positive electrode active material layer; 50, negative electrode plate; 51, negative electrode body; 52, negative electrode active material layer; 60, barrier layer; 61, conductive portion; 62, insulating portion; 70, isolation membrane; 81, bending area; 82, straight area; SS1, inner circle area; SS2, outer circle area; X, width direction. DETAILED DESCRIPTION
[0049] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.
[0050] In the description of this application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly perpendicular, but is within the allowable error range. "Parallel" is not strictly parallel, but is within the allowable error range.
[0051] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the 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 in this application may be combined with other embodiments.
[0052] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of this application. In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.
[0053] In this application, battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.
[0054] The battery device mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include multiple battery cells, which are connected in series, parallel, or hybrid via a busbar.
[0055] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells. For example, the battery cell assembly may be a battery module, which is formed by arranging and securing multiple battery cells to form a single module. For example, a battery module may be formed by bundling multiple battery cells using cable ties.
[0056] In some embodiments, the battery device may be a battery pack, which includes a case and one or more battery cell assemblies, wherein the battery cell assemblies are housed in the case.
[0057] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box by fixing the battery module in the box.
[0058] As an example, the battery cell assembly may also be housed in the box by directly fixing the plurality of battery cells to the box.
[0059] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.
[0060] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.
[0061] Please refer to Figure 1 , Figure 1Schematic diagram of the structure of the vehicle provided for some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery device 100 is provided inside the vehicle 1000, and the battery device 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000. For example, the battery device 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.
[0062] In some embodiments of the present application, the battery device 100 can serve not only as an operating power source for the vehicle 1000 , but also as a driving power source for the vehicle 1000 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000 .
[0063] Please refer to Figure 2 , Figure 2 Exploded diagram of the device provided in some embodiments of the present application. The battery device 100 includes a battery case and a battery cell 20. In some embodiments, the battery case may include an upper cover 10 and a case 30, the upper cover 10 and the case 30 covering each other, and the upper cover 10 and the case 30 jointly define a receiving cavity for accommodating the battery cell 20. The case 30 may be a hollow structure with one end open, and the upper cover 10 may be a plate-like structure, the upper cover 10 covering the open side of the case 30, so that the upper cover 10 and the case 30 jointly define a receiving cavity; the upper cover 10 and the case 30 may also be hollow structures with one side open, the open side of the upper cover 10 covering the open side of the case 30. Of course, the battery case formed by the upper cover 10 and the case 30 may be in various shapes, such as a cylinder, a cuboid, etc.
[0064] Figure 3 This is a schematic diagram of the structure of the battery module of some embodiments of the present application. In the battery device 100, there can be multiple battery cells 20, and the multiple battery cells 20 can be connected in series, in parallel, or in mixed connection. Mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 can be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box; of course, the battery device 100 can also be in the form of multiple battery cells 20 first connected in series, in parallel, or in mixed connection to form a battery module 400, and the multiple battery modules 400 are then connected in series, in parallel, or in mixed connection to form a whole, and accommodated in the box. The battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.
[0065] Each battery cell 20 may be a secondary battery cell or a primary battery cell; it may also be a lithium-sulfur battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.
[0066] Please refer to Figure 4 , Figure 4 Schematic diagram of the exploded structure of a battery cell provided in some embodiments of the present application. A battery cell 20 is the smallest unit that makes up a battery. A battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.
[0067] The end cap 21 is a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 can be adapted to the shape of the housing 22 to fit the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as an aluminum alloy). This prevents the end cap 21 from deforming when subjected to compression or collision, thereby providing the battery cell 20 with greater structural strength and improved safety. Functional components such as electrode terminals 26 can be provided on the end cap 21. The electrode terminals 26 can be used to electrically connect to the electrode assembly 23 to output or input electrical energy to the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for relieving internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any specific limitations on this. In some embodiments, an insulating member may be provided inside the end cap 21 to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, or the like.
[0068] When a lithium-ion battery is recharged, lithium ions are deintercalated from the positive electrode and embedded in the negative electrode. However, some abnormal situations may occur, such as insufficient lithium embedding space in the negative electrode, too much resistance to lithium ion embedding in the negative electrode, or lithium ions being deintercalated from the positive electrode too quickly. The deintercalated lithium ions cannot be embedded in the negative electrode in equal amounts. The lithium ions that cannot be embedded in the negative electrode can only obtain electrons on the surface of the negative electrode, thereby forming a silvery-white metallic lithium element. This is the lithium plating phenomenon. Especially in the bending area, the bending length of the positive electrode sheet is greater than the bending length of the negative electrode sheet, resulting in the negative electrode sheet in the bending area having less lithium embedding sites than the number of lithium ions that can be provided by its adjacent positive electrode sheet. Therefore, when the battery is charging, lithium plating is prone to occur in the bending area.
[0069] In order to solve the above technical problems, an embodiment of the present application provides a battery cell, which includes a shell and an electrode assembly arranged in the shell, the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a barrier layer, the positive electrode sheet includes a positive electrode main body and a positive electrode active material layer arranged on the positive electrode main body; the negative electrode sheet, the positive electrode sheet and the negative electrode sheet are wound to form a bending area; the barrier layer is located in the bending area, and the barrier layer is arranged on the side of the positive electrode sheet facing the negative electrode sheet, and the barrier layer includes at least a conductive part, and the conductive part is electrically connected to the positive electrode main body.
[0070] In the above solution, by providing a barrier layer between the positive and negative electrode sheets, the barrier layer can prevent ions released from the positive electrode active material from being embedded in the bend area of the negative electrode sheet, thereby reducing lithium plating. Furthermore, the barrier layer includes at least a conductive portion. By electrically connecting the conductive portion of the barrier layer to the main body of the positive electrode, the barrier layer and the positive electrode sheet can be brought to the same potential. Since the lithium ions of the positive electrode active material in the bend area are not driven by an electric potential, they cannot be released, further reducing lithium plating in the battery cell.
[0071] Figure 5 It is a schematic structural diagram of the bending area of the electrode assembly in some embodiments of the present application.
[0072] like Figure 5 As shown, in the first aspect, an embodiment of the present application provides a battery cell 20, the battery cell 20 includes a shell 22 and an electrode assembly 23 arranged in the shell 22, the electrode assembly 23 includes a positive electrode sheet 40, a negative electrode sheet 50 and a barrier layer 60, the positive electrode sheet 40 includes a positive electrode main body 41 and a positive electrode active material layer 42 arranged on the positive electrode main body 41; the positive electrode sheet 40 and the negative electrode sheet 50 are wound to form a bending area 81; the barrier layer 60 is located in the bending area 81, and the barrier layer 60 is arranged on the side of the positive electrode sheet 40 facing the negative electrode sheet 50, and the barrier layer 60 includes at least a conductive part 61, and the conductive part 61 is electrically connected to the positive electrode main body 41.
[0073] The positive electrode sheet 40 can also be called the cathode sheet. The positive electrode body 41 is a metal substrate, such as aluminum foil or an aluminum alloy. Positive electrode active material layers 42 can be provided on both surfaces of the positive electrode body 41. The positive electrode active material in the positive electrode active material layer 42 can be lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate, or lithium nickel cobalt manganese oxide.
[0074] The negative electrode sheet 50, also known as the anode sheet, includes a negative electrode body 51 and a negative electrode active material layer 52 disposed on the negative electrode body 51. The negative electrode body 51 is a metal substrate, such as copper foil. The negative electrode active material layer 52 can be disposed on both surfaces of the negative electrode body 51. The negative electrode active material layer 52 can be graphite or silicon.
[0075] A separator 70 may be positioned between the negative electrode sheet 50 and the positive electrode sheet 40, as well as on the outside of the positive electrode sheet 40. The negative electrode sheet 50, separator 70, positive electrode sheet 40, and separator 70 may be stacked sequentially and then wound together to form the wound electrode assembly 23. The separator 70 primarily prevents direct electron flow between the two electrode sheets while allowing particle transport. The separator 70 is a thin film that prevents short circuits between the positive and negative electrodes, ensuring proper battery operation. Specifically, the separator 70 is an electronic insulator that blocks direct electron flow between the positive and negative electrodes, thereby preventing internal short circuits, direct energy dissipation, and premature battery failure. Although the separator 70 blocks electron flow, it allows ions to flow between the positive and negative electrodes. This is because the operating principle of a battery involves the movement of ions in an electrolyte, from the positive electrode through the electrolyte to the negative electrode, completing the electrochemical reaction. The separator 70 provides a pathway for ion transport between the positive and negative electrodes, facilitating the battery's charge and discharge processes.
[0076] Figure 6 It is a schematic structural diagram of the electrode assembly of some embodiments of the present application.
[0077] like Figure 6 As shown, after winding, the unbent areas of the electrode assembly 23 are straight regions 82, and the bent areas are bent regions 81. The electrode assembly 23 has a multi-turn structure, with the innermost turns representing the inner region SS1 and the outermost turns representing the outer region SS2. Generally, the innermost layer is the negative electrode sheet 50, followed by the positive electrode sheet 40. The barrier layer 60 is disposed on the concave surface of the positive electrode sheet 40. It should be noted that the convex surface faces the outer region SS2, while the concave surface faces the inner region SS1.
[0078] The barrier layer 60 may be provided in both the outer region SS2 and the inner region SS1 , or only in the inner region SS1 , or only at the innermost side of the bending zone 81 .
[0079] The conductive portion 61 of the barrier layer 60 is made of a metal material, such as aluminum or an aluminum alloy. The material of the conductive portion 61 is consistent with that of the positive electrode main body 41, which reduces the introduction of new substances and the risk of affecting the electrochemical reaction. The conductive portion 61 can be electrically connected to the positive electrode main body 41 by welding or clamping.
[0080] In the above solution, by providing a barrier layer 60 between the positive electrode sheet 40 and the negative electrode sheet 50, the barrier layer 60 can prevent ions released from the positive electrode active material from being embedded in the bend region 81 of the negative electrode sheet 50, thereby reducing lithium plating. Furthermore, the barrier layer 60 includes at least a conductive portion 61. By electrically connecting the conductive portion 61 of the barrier layer 60 to the positive electrode main body 41, the barrier layer 60 and the positive electrode sheet 40 can be brought to an equipotential. Since the lithium ions of the positive electrode active material in the bend region 81 are not driven by an electric potential, they cannot be released, resulting in electrochemical inactivation of the positive electrode active material, further reducing lithium plating in the battery cell 20.
[0081] In some embodiments, the resistivity of the conductive portion 61 is ρ1, and ρ1 satisfies: ρ1<5×10 -8 Ω·m.
[0082] Among them, ρ1 can be less than 5×10 -8 Any value of Ω·m. For example, ρ1 can be 10 -8 Ω·m, 2×10 -8 Ω·m、3×10 -8 Ω·m、4×10 -8 Ω·m、4.9×10 -8 Ω·m, etc.
[0083] For example, the conductive part 61 can be made of metal materials such as aluminum, gold, aluminum, copper, silver, etc., and the selection range is relatively wide.
[0084] In the above solution, the conductive portion 61 has a low resistivity and good conductivity, which can ensure to a certain extent that there is no potential difference between the barrier layer 60 and the positive electrode sheet 40 .
[0085] In some embodiments, ρ1 satisfies: ρ1≤2.8×10 -8 Ω·m.
[0086] Wherein, ρ1 can be less than or equal to 2.8×10 -8 For example, ρ1 can be 1.24×10 -8 Ω·m、1.6×10 -8 Ω·m、2.1×10 -8 Ω·m、2.5×10 -8 Ω·m、2.8×10 -8 Ω·m, etc.
[0087] In the above solution, the conductive performance of the conductive portion 61 is further improved.
[0088] Figure 7 Schematic diagram of the structure of the barrier layer of some embodiments of the present application.
[0089] like Figure 7As shown, in some embodiments, the barrier layer 60 further includes an insulating portion 62 , which is disposed on a side of the conductive portion 61 facing the negative electrode sheet 50 .
[0090] The conductive portion 61 can be formed on the insulating portion 62 by printing or spraying. The conductive portion 61 faces the positive electrode sheet 40 , and the insulating portion 62 faces the negative electrode sheet 50 .
[0091] The insulating portion 62 may be made of a polymer or inorganic oxide having an insulating effect, for example, polypropylene, polyethylene, polyvinyl chloride, magnesium oxide, calcium oxide, aluminum oxide, silicon dioxide, or the like.
[0092] In the above solution, the insulating portion 62 can prevent the positive electrode sheet 40 and the negative electrode sheet 50 in the bending area 81 from contacting each other to a certain extent, thereby preventing the occurrence of a short circuit.
[0093] Optionally, the material of the insulating portion 62 can be the same as that of the isolation film 70 , which facilitates process preparation and reduces costs, does not require the introduction of other new substances, has electrochemical stability, and does not cause additional reactions.
[0094] In some embodiments, the resistivity of the insulating portion 62 is ρ2, and ρ2 satisfies: ρ2>10 14 Ω·cm.
[0095] Among them, ρ2 can be greater than 10 14 For example, ρ2 can be 2×10 14 Ω·cm、3×10 14 Ω·cm、4×10 14 Ω·cm、5×10 14 Ω·cm、6×10 14 Ω·cm, etc.
[0096] In the above solution, the insulating portion 62 has a relatively high resistivity and good insulation performance, thereby improving the insulation effect between the positive electrode sheet 40 and the negative electrode sheet 50 in the bending region 81 .
[0097] In some embodiments, ρ2 satisfies: 10 15 Ω·cm≤ρ2≤10 19 Ω·cm.
[0098] Among them, ρ2 can be 10 15 Ω·cm-10 19 For example, ρ2 can be 2×10 15 Ω·cm, 10 16 Ω·cm, 10 17 Ω·cm, 10 18Ω·cm, 10 19 Ω·cm, etc.
[0099] The resistivity of polypropylene and polyethylene is generally 10 15 Ω·cm-10 19 Ω·cm, the material of the isolation film 70 is usually polypropylene or polyethylene. Therefore, the insulating portion 62 of the barrier layer 60 is made of the same material as the isolation film 70.
[0100] In the above solution, the insulation performance of the insulating portion 62 is further improved.
[0101] In some embodiments, the thicknesses of the conductive portion 61 and the insulating portion 62 are L1 and L2, respectively, and the resistivities of the conductive portion 61 and the insulating portion 62 are ρ1 and ρ2, respectively, wherein (ρ1×L1+ρ2×L2) / (L1+L2)>10 14 Ω·cm.
[0102] (ρ1×L1+ρ2×L2) / (L1+L2) is the average resistivity of the entire barrier layer 60. 14 For example, (ρ1×L1+ρ2×L2) / (L1+L2) can be 2×10 14 Ω·cm、3×10 14 Ω·cm、4×10 14 Ω·cm、5×10 14 Ω·cm、6×10 14 Ω·cm, etc.
[0103] In the above solution, by adjusting the thickness and resistivity of the conductive portion 61 and the insulating portion 62 respectively, the resistivity range of the entire barrier layer 60 is limited, thereby ensuring the insulation effect of the entire barrier layer 60 to a certain extent.
[0104] In some embodiments, 10 15 Ω·cm≤(ρ1×L1+ρ2×L2) / (L1+L2)≤10 19 Ω·cm.
[0105] Among them, (ρ1×L1+ρ2×L2) / (L1+L2) can be 10 15 Ω·cm-10 19 For example, (ρ1×L1+ρ2×L2) / (L1+L2) can be 2×10 15 Ω·cm, 10 16 Ω·cm, 10 17 Ω·cm, 10 18 Ω·cm, 10 19Ω·cm, etc.
[0106] In the above solution, by further limiting the resistivity of the entire barrier layer 60 , the insulation effect of the entire barrier layer 60 is further improved.
[0107] In some embodiments, the barrier layer 60 has a thickness D, where D satisfies: 2 μm≤D≤500 μm.
[0108] The thickness D of the barrier layer 60 may be any value between 2 μm and 500 μm. For example, the thickness D of the barrier layer 60 may be 2 μm, 10 μm, 50 μm, 200 μm, 500 μm, etc.
[0109] In the above solution, the thickness of the barrier layer 60 is within a moderate range, which can ensure the effect of reducing lithium plating to a certain extent, while not occupying too much space of the electrode assembly 23 and reducing the impact on the capacity of the battery cell 20.
[0110] In some embodiments, D satisfies: 5 μm≤D≤20 μm.
[0111] The thickness D of the barrier layer 60 may be any value between 5 μm and 20 μm. For example, the thickness D of the barrier layer 60 may be 5 μm, 7 μm, 12 μm, 15 μm, 20 μm, etc.
[0112] In the above solution, by further limiting the thickness range of the barrier layer 60 , the effect of lithium plating is further ensured, and the impact on the capacity of the battery cell 20 is reduced.
[0113] Figure 8 Schematic diagram of the connection between the barrier layer and the positive electrode sheet in some embodiments of the present application; Figure 9 This is a schematic diagram of the connection between the barrier layer and the positive electrode plate at another angle in some embodiments of the present application.
[0114] Please refer to Figure 8 and Figure 9 In some embodiments, the conductive portion 61 is welded to the positive electrode main body 41 .
[0115] The conductive portion 61 is directly welded to a portion of the positive electrode body portion 41 that is not coated with the positive electrode active material.
[0116] In the above solution, the conductive portion 61 is electrically connected to the positive electrode main body 41 by welding, without introducing other substances, thereby reducing the impact on the electrochemical performance of the electrode assembly 23.
[0117] In some embodiments, both ends of the positive electrode body 41 along the width direction X of the positive electrode sheet 40 are protruded relative to the positive electrode active material layer 42 to form protrusions 411 ; and opposite ends of the barrier layer 60 along the width direction X are welded to the protrusions 411 respectively.
[0118] No positive electrode active material is provided on the surface of the protrusion 411 . The barrier layer 60 crosses the positive electrode active material layer 42 of the positive electrode sheet 40 along the width direction X. Both ends are directly welded to the protrusion 411 , and then the electrode assembly 23 is wound after welding.
[0119] In the above solution, by welding the two ends of the barrier layer 60 along the width direction X to the protrusions 411 of the positive electrode body 41 , the connection stability between the barrier layer 60 and the positive electrode body 41 can be improved.
[0120] In some embodiments, the area of the electrode assembly 23 close to the winding center is the inner circle area SS1, and the area away from the winding center is the outer circle area SS2. The barrier layer 60 is located in the inner circle area SS1.
[0121] Since the inner circle area SS1 has a greater bending force than the outer circle area SS2, in the inner circle area SS1, the bending length of the positive electrode sheet 40 is much greater than the bending length of the negative electrode sheet 50, and lithium deposition is more likely to occur in the inner circle area SS1 than in the outer circle area SS2, so the barrier layer 60 is set in the inner circle area SS1 where lithium deposition is more likely to occur.
[0122] In the above solution, by disposing the barrier layer 60 in the inner region SS1 , the space occupied by the electrode assembly 23 can be reduced, thereby reducing the impact on the capacity of the battery cell 20 .
[0123] In some embodiments, the barrier layer 60 is disposed at the innermost position of the inner circle region SS1 .
[0124] That is, the barrier layer 60 is disposed at the corner of the first bending circle and the second bending circle. The first bending circle is the negative electrode sheet 50, and the second bending circle is the positive electrode sheet 40. Because the bending force is the greatest at the innermost part of the inner circle area SS1 and lithium deposition is most likely to occur, the barrier layer 60 is disposed at the innermost part of the inner circle area SS1 where lithium deposition is most likely to occur.
[0125] In the above solution, by arranging the barrier layer 60 at the innermost position where lithium deposition is most likely to occur, the impact on the capacity of the battery cell 20 is further reduced.
[0126] Secondly, an embodiment of the present application further provides an electrode assembly 23, including a positive electrode sheet 40, a negative electrode sheet 50 and a barrier layer 60, the positive electrode sheet 40 includes a positive electrode main body 41 and a positive electrode active material layer 42 arranged on the positive electrode main body 41; the negative electrode sheet 50, the positive electrode sheet 40 and the negative electrode sheet 50 are wound to form a bending area 81; the barrier layer 60 is located in the bending area 81, the barrier layer 60 is arranged on the concave surface of the positive electrode sheet 40, facing the negative electrode sheet 50, the barrier layer 60 includes at least a conductive part 61, and the conductive part 61 is electrically connected to the positive electrode main body 41.
[0127] In a third aspect, an embodiment of the present application further provides a battery device 100 , comprising a battery cell 20 according to any of the above embodiments.
[0128] In a fourth aspect, an embodiment of the present application further provides an electrical device, comprising the above-mentioned battery device 100, wherein the battery device 100 is used to provide electrical energy.
[0129] According to some embodiments of the present application, a battery cell 20 is provided. The battery cell 20 includes a housing 22 and an electrode assembly 23 disposed within the housing 22. The electrode assembly 23 includes a positive electrode sheet 40, a negative electrode sheet 50, and a barrier layer 60. The positive electrode sheet 40 includes a positive electrode body 41 and a positive electrode active material layer 42 disposed on the positive electrode body 41. The negative electrode sheet 50 and the positive electrode sheet 40 and the negative electrode sheet 50 are wound to form a bending region 81. The barrier layer 60 is located in the bending region 81. The barrier layer 60 is disposed on the side of the positive electrode sheet 40 facing the negative electrode sheet 50. The barrier layer 60 includes at least a conductive portion 61, which is electrically connected to the positive electrode body 41. The barrier layer 60 also includes an insulating portion 62, which is disposed on the side of the conductive portion 61 facing the negative electrode sheet 50.
[0130] 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 make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions 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: The invention comprises a shell and an electrode assembly disposed in the shell, wherein the electrode assembly comprises: A positive electrode sheet, comprising a positive electrode main body and a positive electrode active material layer disposed on the positive electrode main body; A negative electrode sheet, wherein the positive electrode sheet and the negative electrode sheet are wound to form a bending area; The barrier layer is located in the bending area, and is arranged on the side of the positive electrode sheet facing the negative electrode sheet. The barrier layer at least includes a conductive portion, and the conductive portion is electrically connected to the positive electrode main body.
2. The battery cell according to claim 1, wherein: The resistivity of the conductive portion is ρ1, and the ρ1 satisfies: ρ1<5×10 -8 Ω·m.
3. The battery cell according to claim 2, characterized in that: The ρ1 satisfies: ρ1≤2.8×10 -8 Ω·m.
4. The battery cell according to claim 1, wherein: The barrier layer further includes an insulating portion, which is arranged on a side of the conductive portion facing the negative electrode plate.
5. The battery cell according to claim 4, characterized in that The resistivity of the insulating portion is ρ2, and the ρ2 satisfies: ρ2>10 14 Ω·cm.
6. The battery cell according to claim 5, characterized in that The ρ2 satisfies: 10 15 Ω·cm≤ρ2≤10 19 Ω·cm.
7. The battery cell according to claim 4, characterized in that The thicknesses of the conductive portion and the insulating portion are L1 and L2 respectively, and the resistivities of the conductive portion and the insulating portion are ρ1 and ρ2 respectively, wherein (ρ1×L1+ρ2×L2) / (L1+L2)>10 14 Ω·cm.
8. The battery cell according to claim 7, characterized in that 10 15 Ω·cm≤(ρ1×L1+ρ2×L2) / (L1+L2)≤10 19 Ω·cm。 9. The battery cell according to claim 1, characterized in that The thickness of the barrier layer is D, and D satisfies: 2 μm≤D≤500 μm.
10. The battery cell according to claim 9, characterized in that The D satisfies: 5 μm≤D≤20 μm.
11. The battery cell according to claim 1, wherein The conductive portion is welded to the positive electrode main body.
12. The battery cell according to claim 11, characterized in that Both ends of the positive electrode main body along the width direction of the positive electrode sheet are protruded relative to the positive electrode active material layer to form protruding portions; Two opposite ends of the barrier layer along the width direction are respectively welded to the protruding portions.
13. The battery cell according to claim 1, characterized in that The area of the electrode assembly close to the winding center is the inner circle area, and the area away from the winding center is the outer circle area. The barrier layer is located in the inner circle area.
14. The battery cell according to claim 13, characterized in that The barrier layer is arranged at the innermost position of the inner circle area.
15. An electrode assembly, characterized in that: include: A positive electrode sheet, comprising a positive electrode main body and a positive electrode active material layer disposed on the positive electrode main body; A negative electrode sheet, wherein the positive electrode sheet and the negative electrode sheet are wound to form a bending area; The barrier layer is located in the bending area, and is arranged on the side of the positive electrode sheet facing the negative electrode sheet. The barrier layer at least includes a conductive portion, and the conductive portion is electrically connected to the positive electrode main body.
16. A battery device, characterized in that: The invention comprises a battery cell according to any one of claims 1 to 14.
17. An electrical device, characterized in that: The battery device according to claim 16 is included for providing electrical energy.