Cathode-coated anode structure of secondary battery
By adopting a gradient-width anode sheet design in lithium-ion batteries, the problem of insufficient energy density in traditional design is solved, the energy density of the battery cell is improved, and the needs of high-energy density application scenarios are adapted.
Patent Information
- Application Number
- CN202422035269.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-21
- Publication Date
- 2025-08-26
- Estimated Expiration
- 2034-08-21
AI Technical Summary
The energy density of existing lithium-ion batteries has approached the theoretical limit. The traditional anode-pack cathode structure design has led to an increase in the proportion of inactive substances, affecting the energy density of the battery cell, and it is difficult to meet the needs of high energy density.
The gradient-width anode sheet design is adopted, combined with appropriate angles and width differences to ensure stability of the winding process, while reducing the redundancy of the anode ultra-cathode width and improving the energy density of the battery cell.
By optimizing the width design of the anode sheet, the energy density of the battery cell is improved, the impact of process fluctuations on the energy density is reduced, and the application needs of high energy density is met.
Smart Images
Figure CN223273327U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of secondary batteries, in particular to an anode-cathode package structure of a secondary battery. Background Art
[0002] Secondary batteries are batteries that undergo cyclical charge and discharge. In recent years, with the rapid development of the information communications and new energy industries, secondary batteries, due to their outstanding performance and practical advantages, have been widely used in many fields such as electric vehicles, consumer electronics, and large-scale energy storage, becoming the mainstream direction of the electrification era. Typical secondary batteries include lithium-ion batteries, sodium-ion batteries, and nickel-cadmium batteries. Lithium-ion batteries and sodium-ion batteries have experienced rapid development due to their ultra-high energy density and long cycle stability, and are currently gaining widespread market acceptance and recognition.
[0003] The market is currently demanding ever-increasing energy density for secondary batteries. Taking lithium-ion batteries as an example, the energy density of mainstream lithium iron phosphate batteries is currently below 200Wh / kg, while that of ternary lithium batteries is between 200-300Wh / kg. The energy density of lithium-ion batteries falls far short of meeting the demands of significant development, limiting their application in various scenarios. To meet the demands of a wider range of applications, batteries' energy and power density must be significantly increased.
[0004] The energy density of existing lithium-ion batteries is already close to the theoretical limit, and the key materials that affect the battery energy density, such as the positive electrode and the negative electrode, have a gram capacity close to the theoretical limit. Therefore, it is difficult to further improve the battery energy density from the material level. Therefore, new ways to improve the battery energy density are needed.
[0005] Taking lithium-ion batteries as an example, during the charging process, lithium ions will be released from the cathode and then embedded in the anode sites. If the anode has insufficient sites for embedding, lithium ions will accumulate on the anode surface to form lithium dendrites. In severe cases, they may pierce the diaphragm, causing a short circuit inside the battery cell, and then causing thermal runaway of the battery cell. Therefore, when designing the battery cell pole piece, the anode width is usually about 0.2-8mm wider than the cathode width, which is generally referred to as anode-wrapped cathode. If the number of winding layers is large, the anode super-cathode width is usually slightly larger to prevent cathode-wrapped anode abnormalities caused by offset during the winding process; if the number of winding layers is small, the anode super-cathode width is usually slightly smaller, and the winding process is less affected. The structural design of the anode-wrapped cathode will inevitably increase the mass proportion of inactive substances, thereby reducing the energy density of the battery cell. For applications such as drones that require high-energy-density batteries, their energy density will directly affect the product's application capabilities. Utility Model Content
[0006] The utility model aims to provide a secondary battery anode-cathode package structure, which has the characteristics of high energy density, small process fluctuation and simple control.
[0007] The utility model can be realized by the following technical solutions:
[0008] The utility model discloses an anode-cathode package structure for a secondary battery, comprising a cathode sheet, an anode sheet, and a separator arranged between the cathode sheet and the anode sheet. The anode sheet is an anode sheet with a gradually changing width. When winding, the width of the anode sheet at the head of the battery cell exceeding the cathode sheet is W1 and W1', wherein W1 is the width of the anode sheet at the wound inner circle exceeding the cathode sheet, and W1' is the width of the anode sheet at the wound outer circle exceeding the cathode sheet. When winding, the width of the anode sheet at the tail of the battery cell exceeding the cathode sheet is W2 and W2', wherein W2 is the width of the anode sheet at the wound inner circle exceeding the cathode sheet, and W2' is the width of the anode sheet at the wound outer circle exceeding the cathode sheet. The width difference between the anode sheet and the cathode sheet at the same position along the winding direction is W, and the relationship between W and W1, W2, W1', and W2 is: W=W1+W2=W1'+W2'.
[0009] Furthermore, the angle between the width and length of the anode sheet along the winding direction when the anode sheet is cut is α, and the angle between the width and length of the anode sheet along the winding direction when the anode sheet is cut satisfies 90.02°≤α≤90.2°. If the angle is too small, the outer ring of the anode may not be enough to cover the cathode, which may lead to safety hazards such as lithium deposition. If the angle is too large, the outer ring of the anode may be too much over the cathode, resulting in an excessively high proportion of inactive material, affecting its energy density.
[0010] Furthermore, when the cathode sheet is cut, the angle between the width and length along the winding direction is β, and when the cathode sheet is cut, the angle between the width and length along the winding direction is β which is 90°.
[0011] Furthermore, the width difference between the cathode sheet and the anode sheet along the winding direction always satisfies 0.4≤W≤16, ensuring that the length of the top and bottom anode sheets exceeding the cathode sheet always satisfies 0.2≤W1, W2, W1', W2'≤8 during winding.
[0012] Furthermore, the secondary battery is a sodium ion battery or a lithium ion battery.
[0013] Furthermore, the separator is a PP film, a PE film, a PP / PE composite film or a non-woven fabric film.
[0014] Furthermore, the cathode piece is provided with a cathode ear at its head, and the anode piece is provided with an anode ear at its head, and the cathode ear and the anode ear are staggered in position.
[0015] Furthermore, the sodium ion battery is a polyanion material sodium ion battery, a layered oxide material sodium ion battery or a Prussian blue material sodium ion battery; the lithium ion battery is a lithium cobalt oxide battery, a lithium manganese oxide battery, a ternary material battery or a lithium iron phosphate battery.
[0016] Furthermore, after the secondary battery core is formed, it is packaged in a cylindrical steel shell, aluminum-plastic film or aluminum shell.
[0017] Furthermore, the current collectors of the cathode sheet and the anode sheet are copper foil, aluminum foil, copper mesh or aluminum mesh.
[0018] The utility model provides a secondary battery anode-cathode structure, which has the following beneficial effects:
[0019] In the prior art, in the traditional battery winding structure, the anode width and cathode width are fixed, and the anode super-cathode width is also a fixed value. In order to prevent the anode and cathode pole pieces from being offset due to manufacturing fluctuations during the winding process, which results in the anode being unable to super-cathode abnormalities, the anode super-cathode width is usually designed to be too redundant, which will increase the mass proportion of inactive substances in the battery cell, thereby reducing the energy density of the battery cell. In order to fully improve the energy density of the battery cell and prevent the anode super-cathode width from being excessively designed, the utility model adopts the gradient width anode of the utility model. The anode width continuously increases along the winding direction, which can avoid the influence of manufacturing process fluctuations on the anode-cathode package and also help to improve the energy density of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Attachment Figure 1 This is a schematic diagram of the pole piece winding structure in the prior art;
[0021] Attachment Figure 2 This is a schematic diagram of the anode-cathode structure of a secondary battery of the utility model;
[0022] Attachment Figure 3 This is a schematic diagram of an anode sheet of an anode-cathode structure of a secondary battery of the present invention;
[0023] Attachment Figure 4 This is a schematic diagram of a cathode sheet of an anode-cathode structure of a secondary battery of the utility model;
[0024] The reference numerals in the drawings include: 100, anode sheet; 110, anode lug; 200, cathode sheet; 210, cathode lug. DETAILED DESCRIPTION
[0025] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in further detail below in conjunction with embodiments.
[0026] like Figure 2-4As shown, the utility model discloses an anode-cathode structure of a secondary battery, comprising a cathode sheet 200, an anode sheet 100 and a separator arranged between the cathode sheet 200 and the anode sheet 100, wherein the anode sheet 100 is an anode sheet with a gradually changing width; when winding, the width of the anode sheet 200 at the head of the battery cell exceeding the cathode sheet 200 is W1 and W1', wherein W1 is the width of the anode sheet 100 at the wound inner circle exceeding the cathode sheet, and W1' is the width of the anode sheet 1 at the wound outer circle exceeding the cathode sheet 200; when winding, the width of the anode sheet 100 at the tail of the battery cell exceeding the cathode sheet 200 is W2 and W2' respectively, wherein W2 is the width of the anode sheet 100 at the wound inner circle exceeding the cathode sheet 200, and W2' is the width of the anode sheet 100 at the wound outer circle exceeding the cathode sheet 200; the width difference between the anode sheet and the cathode sheet at the same position along the winding direction is W, and the relationship between W and W1, W2, W1', and W2 is: W=W1+W2 =W1'+W2'.
[0027] like Figure 3 As shown, the angle between the width and length of the anode sheet along the winding direction when the anode sheet is cut is α, and the angle between the width and length of the anode sheet along the winding direction when the anode sheet is cut satisfies 90.02°≤α≤90.2°.
[0028] like Figure 4 As shown, the angle between the width and length of the cathode sheet along the winding direction when it is cut is β, and the angle between the width and length along the winding direction when it is cut is β which is 90°.
[0029] Furthermore, the width difference between the cathode sheet and the anode sheet along the winding direction always satisfies 0.4≤W≤16.
[0030] Furthermore, the secondary battery is a sodium ion battery or a lithium ion battery.
[0031] Furthermore, the separator is a PP film, a PE film, a PP / PE composite film or a non-woven fabric film.
[0032] like Figure 2-4 As shown, the cathode plate 200 is provided with a cathode ear 210 at its head, and the anode plate 100 is provided with an anode ear 110 at its head, and the cathode ear 210 and the anode ear 110 are staggered in position.
[0033] Furthermore, the sodium ion battery is a polyanion material sodium ion battery, a layered oxide material sodium ion battery or a Prussian blue material sodium ion battery; the lithium ion battery is a lithium cobalt oxide battery, a lithium manganese oxide battery, a ternary material battery or a lithium iron phosphate battery.
[0034] Furthermore, after the secondary battery core is formed, it is packaged in a cylindrical steel shell, aluminum-plastic film or aluminum shell.
[0035] Furthermore, the current collectors of the cathode sheet and the anode sheet are copper foil, aluminum foil, copper mesh or aluminum mesh.
[0036] Example 1
[0037] This embodiment provides a novel anode sheet-cathode sheet structure, which includes anode sheets with gradient widths and cathode sheets with fixed widths.
[0038] The gradient width anode sheet has an included angle α of 90.02° between the width and length along the winding direction when the anode sheet is cut. The width of the anode sheet at the edge of the inner circle is 106.5 mm, the winding length of the anode sheet is 2125.3 mm, and the width of the anode sheet at the edge of the outer circle is 108.0 mm.
[0039] The cathode sheet width is fixed. The cathode sheet width at the edge of the inner winding is 106.1 mm, the cathode sheet winding length is 2120.3 mm, and the cathode sheet width at the edge of the outer winding is 106.1 mm.
[0040] Example 2
[0041] This embodiment provides a novel anode sheet-cathode sheet structure, which includes anode sheets with gradient widths and cathode sheets with fixed widths.
[0042] The gradient width anode sheet has an included angle α of 90.2° between the width and length along the winding direction when the anode sheet is cut. The width of the anode sheet at the edge of the inner circle is 84.7 mm, the winding length of the anode sheet is 681.2 mm, and the width of the anode sheet at the edge of the outer circle is 89.4 mm.
[0043] The cathode sheet width is fixed. The width of the cathode sheet at the edge of the inner winding is 84.3 mm, the cathode sheet winding length is 677.2 mm, and the width of the cathode sheet at the edge of the outer winding is 84.3 mm.
[0044] Comparative Example 1
[0045] This comparative example provides a conventional anode sheet-cathode sheet structure, which comprises a fixed-width anode sheet and a fixed-width cathode sheet.
[0046] The anode sheet has a fixed width. The width of the anode sheet at the edge of the inner winding is 106.5 mm, the winding length of the anode sheet is 2125.3 mm, and the width of the anode sheet at the edge of the outer winding is 106.5 mm.
[0047] The cathode sheet width is fixed. The cathode sheet width at the edge of the inner winding is 106.1 mm, the cathode sheet winding length is 2120.3 mm, and the cathode sheet width at the edge of the outer winding is 106.1 mm.
[0048] Comparative Example 2
[0049] This comparative example provides a conventional anode sheet-cathode sheet structure, which comprises a fixed-width anode sheet and a fixed-width cathode sheet.
[0050] The anode sheet has a fixed width. The width of the anode sheet at the edge of the inner winding is 84.7mm, the winding length of the anode sheet is 681.2mm, and the width of the anode sheet at the edge of the outer winding is 84.7mm.
[0051] The cathode sheet width is fixed. The width of the cathode sheet at the edge of the inner winding is 84.3 mm, the cathode sheet winding length is 677.2 mm, and the width of the cathode sheet at the edge of the outer winding is 84.3 mm.
[0052] Comparative Example 3
[0053] This comparative example provides a conventional anode sheet-cathode sheet structure, which comprises a fixed-width anode sheet and a fixed-width cathode sheet.
[0054] The anode sheet has a fixed width. The width of the anode sheet at the edge of the inner coil is 89.4mm, the coiled length is 681.2mm, and the width of the anode sheet at the edge of the outer coil is 89.4mm.
[0055] The cathode sheet width is fixed. The width of the cathode sheet at the edge of the inner winding is 84.3 mm, the cathode sheet winding length is 677.2 mm, and the width of the cathode sheet at the edge of the outer winding is 84.3 mm.
[0056] In order to verify the technical effect of the present invention, a comparative test was conducted on the above embodiments, as shown in Table 1:
[0057] Table 1 Statistics of wound cells and finished cells
[0058]
[0059] In the description of the present invention, it should be understood that terms such as "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.
[0060] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined.
[0061] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, indirect connection through an intermediate medium, internal communication between two components, or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.
[0062] The above embodiments are merely specific embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art will be able to make various modifications and improvements without departing from the scope of the present invention, and these obvious alternatives are all within the scope of protection of the present invention.
Claims
1. A secondary battery anode-cathode structure, comprising a cathode sheet, an anode sheet, and a separator disposed between the cathode sheet and the anode sheet, characterized in that: The anode sheet is an anode sheet with a gradually changing width; When winding, the width of the anode sheet and cathode sheet at the head of the cell is W1 and W1', where W1 is the width of the anode sheet and cathode sheet in the inner circle, and W1' is the width of the anode sheet and cathode sheet in the outer circle. When winding, the widths of the anode sheet and cathode sheet at the tail of the cell are W2 and W2' respectively, where W2 is the width of the anode sheet and cathode sheet in the inner circle, and W2' is the width of the anode sheet and cathode sheet in the outer circle. The width difference between the anode sheet and the cathode sheet at the same position along the winding direction is W. The relationship between W and W1, W2, W1', and W2 is: W=W1+W2=W1'+W2'.
2. The secondary battery anode-cathode structure according to claim 1, characterized in that: When the anode sheet is cut, the angle between the width and the length along the winding direction is α, and the angle between the width and the length along the winding direction when the anode sheet is cut meets 90.02°≤α≤90.2°.
3. The secondary battery anode-cathode structure according to claim 1, characterized in that: When the cathode sheet is cut, the angle between the width and length along the winding direction is β, and when the cathode sheet is cut, the angle between the width and length along the winding direction is β which is 90°.
4. The secondary battery anode-cathode structure according to claim 1, wherein: The width difference between the cathode sheet and the anode sheet along the winding direction always satisfies 0.4≤W≤16.
5. The secondary battery anode-cathode structure according to any one of claims 2 to 4, characterized in that: The secondary battery is a sodium ion battery or a lithium ion battery.
6. The secondary battery anode-cathode structure according to claim 5, characterized in that: The separator is a PP film, a PE film, a PP / PE composite film or a non-woven fabric film.
7. The secondary battery anode-cathode structure according to claim 6, characterized in that: The cathode piece is provided with a cathode ear at its head, and the anode piece is provided with an anode ear at its head, and the cathode ear and the anode ear are staggered in position.
8. The secondary battery anode-cathode structure according to claim 7, characterized in that: The sodium ion battery is a polyanion material sodium ion battery, a layered oxide material sodium ion battery or a Prussian blue material sodium ion battery; the lithium ion battery is a lithium cobalt oxide battery, a lithium manganese oxide battery, a ternary material battery or a lithium iron phosphate battery.
9. The secondary battery anode-cathode structure according to claim 8, characterized in that: After the secondary battery core is formed, it is packaged in a cylindrical steel shell, an aluminum-plastic film or an aluminum shell.
10. The secondary battery anode-cathode structure according to claim 9, characterized in that: The current collectors of the cathode sheet and the anode sheet are copper foil, aluminum foil, copper mesh or aluminum mesh.