Electrode assembly, battery cell, and electric device

Abstract

The utility model provides an electrode assembly, a single battery and a power utilization device, the electrode assembly comprises a positive plate, a negative plate and a lithium supplement pole plate which are arranged in an insulation winding mode, the lithium supplement pole plate is arranged on one side, facing a winding center, of the negative plate, and diaphragms are arranged among the positive plate, the negative plate and the lithium supplement pole plate. The innermost layer of the electrode assembly is the lithium supplement pole piece, the lithium supplement pole piece is introduced in the winding process, on the premise that the technology and equipment are not upgraded and improved, lithium supplement is carried out on a battery cell, the lithium supplement pole piece and a negative pole piece are connected during formation for charging and discharging, active lithium on the lithium supplement pole piece is consumed, and the lithium supplement pole piece and the negative pole piece are connected during formation. And forming an SEI film on the surface of the negative electrode and the electrolyte. And then during normal use, the positive plate and the negative plate are connected for charging and discharging. Meanwhile, in the circulation process, when it is found that the battery cell has large capacity fading in a certain circle, the lithium supplementing pole piece and the negative pole piece are connected again, and consumed active lithium is supplemented in the charging process. The lithium supplementing step can be simplified, the operation difficulty is reduced, and the research and development cost is reduced.

Description

Technical Field

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

[0002] During the first charge and discharge process of lithium batteries, the solid electrolyte surface film (SEI film) generated on the negative electrode surface consumes part of the active lithium from the positive electrode material, resulting in irreversible capacity loss, which leads to a decrease in the first coulombic efficiency and capacity of the battery cell, affecting its performance. Studies have found that lithium replenishment or pre-lithium embedding technology can replenish the consumed lithium ions, thereby improving the coulombic efficiency and capacity of the battery cell, and effectively improving the cycle performance and first efficiency of the battery cell.

[0003] Currently, workers in the lithium battery industry are studying the use of lithium foil or lithium powder for pre-lithiation. However, this method requires additional steps to composite the lithium foil or lithium powder with the foil for rolling and transfer, which has disadvantages such as complex production, difficult operation, and increased R&D costs. Summary of the invention

[0004] The purpose of the utility model is to provide an electrode assembly, a battery and an electrical device, which can simplify the lithium replenishment steps, reduce the difficulty of operation and reduce the research and development cost.

[0005] The embodiment of the utility model is achieved as follows:

[0006] In a first aspect, the utility model provides an electrode assembly, comprising a positive electrode sheet, a negative electrode sheet and a lithium-replenishing electrode sheet which are insulated and wound, wherein the lithium-replenishing electrode sheet is arranged on the side of the negative electrode sheet toward the winding center, and a diaphragm is arranged between the positive electrode sheet, the negative electrode sheet and the lithium-replenishing electrode sheet, and the innermost layer of the electrode assembly is the lithium-replenishing electrode sheet.

[0007] In an optional embodiment, the lithium supplement electrode comprises a current collector and a lithium-containing active material layer disposed on at least one surface of the current collector.

[0008] In an optional embodiment, a lithium-containing active material layer is disposed on the surface of the current collector facing the negative electrode sheet.

[0009] In an optional embodiment, the material of the lithium-containing active material layer is one of metallic lithium, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobalt manganese oxide, nickel cobalt aluminum ternary material, lithium-rich layered material, nickel manganese spinel material, and lithium-containing polymer compound.

[0010] In an optional embodiment, along the width direction of the electrode sheet, the negative electrode sheet exceeds the lithium-replenishing electrode sheet, the separator exceeds the negative electrode sheet, and the width of the lithium-replenishing electrode sheet is smaller than the width of the negative electrode sheet.

[0011] In an optional embodiment, the width of the lithium supplement electrode sheet is the same as the width of the positive electrode sheet.

[0012] In an optional embodiment, the separator exceeds the negative electrode sheet by 0.5-4 mm, and the negative electrode sheet exceeds the lithium supplement electrode sheet by 1-4 mm.

[0013] In an optional embodiment, the ratio of the surface density of the lithium-supplementing electrode sheet to the surface density of the negative electrode sheet is 1.2-1.8.

[0014] In a second aspect, the utility model provides a battery cell, comprising an electrode assembly as described in any of the aforementioned embodiments; electrode terminals, comprising a positive terminal connected to the positive electrode sheet, a negative terminal connected to the negative electrode sheet, and a third electrode terminal connected to the lithium supplement electrode sheet; wherein, when charging and discharging are performed with the aid of the negative terminal and the third electrode terminal, the battery can be pre-lithiated.

[0015] In a third aspect, the utility model provides an electrical device, comprising the battery as described above.

[0016] The beneficial effects of the embodiments of the utility model include:

[0017] The utility model provides an electrode assembly, including a positive electrode sheet, a negative electrode sheet and a lithium supplement electrode sheet arranged in an insulated winding arrangement, wherein the lithium supplement electrode sheet is arranged on the side of the negative electrode sheet facing the winding center, and a diaphragm is arranged between the positive electrode sheet, the negative electrode sheet and the lithium supplement electrode sheet, and the innermost layer of the electrode assembly is the lithium supplement electrode sheet. By introducing the lithium supplement electrode sheet during the winding process, the structure supplements lithium to the battery cell without upgrading or improving the process and equipment, and connects the lithium supplement electrode sheet and the negative electrode sheet during formation for charging and discharging, consumes the active lithium on the lithium supplement electrode sheet, and forms an SEI film with the electrolyte on the surface of the negative electrode. Afterwards, during normal use, the positive electrode sheet and the negative electrode sheet are connected for charging and discharging. At the same time, during the cycle process, if it is found that the battery cell has a large capacity attenuation in a certain cycle, the lithium supplement electrode sheet and the negative electrode sheet are connected again to supplement the consumed active lithium during the charging process. It is able to simplify the lithium supplement steps, reduce the difficulty of operation, and reduce the cost of research and development. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1This is a schematic diagram for illustrating the arrangement of the positive electrode sheet, the negative electrode sheet, the lithium supplement electrode sheet, and the diaphragm in the embodiment of the present application;

[0020] Figure 2 This is a schematic diagram of the structure of the lithium-supplementing electrode in the embodiment of the present application;

[0021] Figure 3 This is a schematic diagram for illustrating the size relationship between the negative electrode sheet and the lithium supplement electrode sheet in the embodiment of the present application;

[0022] Figure 4 This is a schematic diagram of the structure of the positive electrode sheet in the embodiment of the present application;

[0023] Figure 5 This is a schematic diagram of the structure of the negative electrode sheet in the embodiment of the present application;

[0024] Figure 6 A schematic diagram of the winding process of the electrode assembly in an embodiment of the present application;

[0025] Figure 7 It is a schematic diagram of the first tab arrangement method in the embodiment of the present application;

[0026] Figure 8 Schematic diagram of the second tab arrangement method in the embodiment of the present application;

[0027] Icon: 10-battery; 100-electrode assembly; 110-positive electrode sheet; 111-second current collector; 1111-second pole ear; 112-second active material layer; 120-negative electrode sheet; 121-third current collector; 1211-third pole ear; 122-third active material layer; 130-lithium replenishing electrode sheet; 131-first current collector; 1311-first pole ear; 132-first active material layer; 140-diaphragm. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0031] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0032] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0033] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Example

[0034] The present application provides an electrode assembly. Figure 1 ,and Figure 6 As shown, Figure 1 This is a schematic diagram for showing the arrangement of the positive electrode sheet, the negative electrode sheet, the lithium supplement electrode sheet, and the diaphragm in the first embodiment of the present application. Figure 1 The electrode assembly shown includes a positive electrode sheet, a negative electrode sheet and a lithium-replenishing electrode sheet that are insulated and wound. The lithium-replenishing electrode sheet is arranged on the side of the negative electrode sheet toward the winding center. A separator is arranged between the positive electrode sheet, the negative electrode sheet and the lithium-replenishing electrode sheet. The innermost layer of the electrode assembly is the lithium-replenishing electrode sheet.

[0035] In the technical solution of the embodiment of the present application, the electrode assembly is a component in which an electrochemical reaction occurs in a battery cell, and the electrode assembly is a wound electrode assembly, such as Figure 6 As shown, the positive electrode sheet, the negative electrode sheet, the lithium supplement electrode sheet, and the diaphragm are wound and arranged. Figure 1 As shown, the lithium replenishing electrode sheet is located at the winding center, that is, the positive electrode sheet, the negative electrode sheet, the lithium replenishing electrode sheet and the separator are wound around the winding center to form a winding structure, and the winding starting end of the lithium replenishing electrode sheet is located at the innermost layer of the electrode assembly.

[0036] Figure 2 , Figure 4 , Figure 5 The structures of the lithium-replenishing electrode sheet, the positive electrode sheet, and the negative electrode sheet of the first embodiment of the present application are respectively shown.

[0037] Figure 2 The schematic diagram of the structure of the lithium supplement pole piece in the embodiment of the present application is as follows. The lithium supplement pole piece comprises a current collector and a lithium-containing active material layer arranged on at least one surface of the current collector. Figure 4 , Figure 5 The structures of the positive electrode sheet and the negative electrode sheet are respectively. Optionally, the positive electrode sheet includes a positive electrode current collector and an active material layer coated on both surfaces of the current collector in the thickness direction, the positive electrode current collector is aluminum foil, and the active material is one or more of nickel-cobalt-manganese ternary material, lithium iron phosphate material, lithium cobalt oxide material, and lithium manganese oxide material. The negative electrode sheet includes a negative electrode current collector and an active material layer coated on both surfaces of the current collector in the thickness direction, the negative electrode current collector is copper foil, and the negative electrode active material is one or more of graphite, hard carbon, and silicon-based materials.

[0038] Optionally, a lithium-containing active material layer is provided on the surface of the current collector facing the negative electrode. Aluminum foil is selected as the current collector of the lithium replenishing electrode. The lithium replenishing electrode can be coated with active material on one side. When coated on one side, the surface opposite to the negative electrode must be coated with active material. It can also be coated with active material on both sides. Users can design the lithium replenishing electrode according to their own needs for lithium replenishment.

[0039] Optionally, the material of the lithium-containing active material layer is one of metallic lithium, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, nickel cobalt manganese oxide, nickel cobalt aluminum ternary material, lithium-rich layered material, nickel manganese spinel material, and lithium-containing polymer compounds. After power is turned on, a conductive path is formed between the lithium supplementing electrode sheet and the first negative electrode sheet, and the lithium ions in these compounds can be separated from the lithium supplementing electrode sheet to form active lithium ions, thereby replenishing the active lithium ions consumed in the battery cell.

[0040] Figure 3 This is a schematic diagram used to show the size relationship between the negative electrode plate and the lithium supplement electrode plate in the embodiment of the present application.

[0041] Optionally, along the width direction of the electrode sheet, the negative electrode sheet exceeds the lithium supplement electrode sheet, the diaphragm exceeds the negative electrode sheet, and the width of the lithium supplement electrode sheet is smaller than the width of the negative electrode sheet. The diaphragm completely wraps the positive electrode sheet, the negative electrode sheet and the lithium supplement electrode sheet inside, so that the positive electrode sheet, the negative electrode sheet and the lithium supplement electrode sheet cannot contact each other, avoiding short circuit.

[0042] Optionally, the width of the lithium supplementing electrode is the same as the width of the positive electrode.

[0043] Optionally, the diaphragm exceeds the negative electrode sheet by 0.5-4mm. Optionally, the diaphragm exceeds the negative electrode sheet by 0.5mm, 1mm, 2mm, 3mm, or 4mm. The negative electrode sheet exceeds the lithium-supplementing electrode sheet by 1-4mm. Optionally, the negative electrode sheet exceeds the lithium-supplementing electrode sheet by 1mm, 2mm, 3mm, or 4mm.

[0044] Optionally, the ratio of the surface density of the lithium-replenishing electrode sheet to the surface density of the negative electrode sheet is 1.2-1.8. Optionally, the ratio of the surface density of the lithium-replenishing electrode sheet to the surface density of the negative electrode sheet is 1.2, 1.4, 1.6, 1.8, so as to achieve sufficient lithium replenishment of the negative electrode sheet. Example

[0045] A battery cell includes an electrode assembly and electrode terminals, wherein the electrode terminals include a positive terminal connected to a positive electrode sheet, a negative terminal connected to a negative electrode sheet, and a third electrode terminal connected to a lithium supplement electrode sheet; wherein, when charging and discharging are performed with the aid of the negative terminal and the third electrode terminal, the battery can be pre-lithiated. Figure 7 and Figure 8 Shown are schematic diagrams of two types of tab settings.

[0046] The lithium replenishing electrode sheet can be used to replenish lithium to the battery cell, and the positive terminal and the negative terminal can be used to realize the charge and discharge function of the battery cell. The third electrode terminal is connected to the lithium replenishing electrode sheet, and the lithium replenishing electrode sheet can be controlled to replenish lithium at an appropriate time through the third electrode terminal, so that lithium replenishment can be realized as needed during the whole life stage of the battery cell, so that the amount of lithium ions in the whole life stage of the battery cell can meet the use requirements, and the cycle life of the battery cell can be effectively improved.

[0047] The battery cell also includes a shell (not shown in the figure), and the electrode assembly is arranged in the shell. The shell is a component used to form the internal environment of the battery cell, wherein the formed internal environment can be used to accommodate the electrode assembly, the electrolyte (not shown in the figure) and other components. The shell can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell can be determined according to the specific shape and size of the electrode assembly. The material of the shell can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose any special restrictions on this. Example

[0048] An electrical device, including a battery cell of any of the above embodiments, the battery cell is used to provide electrical energy. It is understandable that the electrical device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle can be a fuel vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, and the like; the spacecraft includes an airplane, a rocket, a space shuttle, and a spacecraft, and the like; the electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, and the like; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and an electric tool for railways, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator, and an electric planer, and the like. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0049] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. An electrode assembly, characterized in that: It comprises a positive electrode sheet, a negative electrode sheet and a lithium supplement electrode sheet which are insulated and wound. The lithium supplement electrode sheet is arranged on the side of the negative electrode sheet facing the winding center. A diaphragm is arranged between the positive electrode sheet, the negative electrode sheet and the lithium supplement electrode sheet. The innermost layer of the electrode assembly is the lithium supplement electrode sheet.

2. The electrode assembly according to claim 1, characterized in that: The lithium supplement electrode comprises a current collector and a lithium-containing active material layer arranged on at least one surface of the current collector.

3. The electrode assembly according to claim 2, characterized in that: A lithium-containing active material layer is disposed on the surface of the current collector facing the negative electrode sheet.

4. The electrode assembly according to claim 2, characterized in that: The material of the lithium-containing active material layer is one of metallic lithium, lithium cobaltate, lithium manganate, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobalt manganese oxide, nickel cobalt aluminum ternary material, lithium-rich layered material, nickel manganese spinel material, and lithium-containing polymer compound.

5. The electrode assembly according to claim 2, characterized in that: Along the width direction of the electrode sheet, the negative electrode sheet exceeds the lithium supplement electrode sheet, the separator exceeds the negative electrode sheet, and the width of the lithium supplement electrode sheet is smaller than the width of the negative electrode sheet.

6. The electrode assembly according to claim 5, characterized in that: The width of the lithium supplement electrode sheet is the same as that of the positive electrode sheet.

7. The electrode assembly according to claim 2, characterized in that: The separator exceeds the negative electrode sheet by 0.5-4 mm, and the negative electrode sheet exceeds the lithium supplement electrode sheet by 1-4 mm.

8. The electrode assembly according to claim 3, characterized in that: The ratio of the surface density of the lithium supplementing electrode sheet to the surface density of the negative electrode sheet is 1.2-1.

8.

9. A battery cell, characterized in that: include: The electrode assembly according to any one of claims 1 to 8; Electrode terminals, including a positive terminal connected to the positive electrode sheet, a negative terminal connected to the negative electrode sheet, and a third electrode terminal connected to the lithium supplement electrode sheet; When charging and discharging are performed via the negative electrode terminal and the third electrode terminal, the battery can be pre-lithiated.

10. An electrical device, characterized in that: Comprising the battery cell according to claim 9.

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