Roll core structure and laminated core
By designing empty foil areas for the positive and negative electrodes and setting an insulating layer in the lithium battery core structure, the problems of low space utilization and poor flatness of wound cells are solved, achieving higher energy density and cell quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-03-06
AI Technical Summary
The existing lithium battery stacked structure has low production efficiency and large capacity loss after the welded soft tabs break. The wound cell has low space utilization, poor flatness and is prone to lithium deposition, making it difficult to guarantee cell quality.
A wound core structure is designed, including a positive electrode sheet, a negative electrode sheet, and a separator sandwiched between them. The structure is formed by winding. Empty foil areas are set in the flat areas on the sides of the positive and negative electrode sheets to reduce active materials and optimize surface flatness. An insulating layer is set in the empty foil area of the positive electrode to prevent short circuit.
It improves the space utilization and energy density of the core, optimizes the flatness of the cell, enhances the safety and stability of the cell, prevents lithium plating, and improves the quality of the cell.
Smart Images
Figure CN223977931U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of lithium battery technology, and in particular to a core structure and stacked core. Background Technology
[0002] Currently, the main structures of bare battery cells are stacked and wound. The stacked structure has problems such as low production efficiency and large capacity loss after the welded soft tabs break. The existing wound battery cells generally wind the electrode sheets coated with active materials to form a wound body. This design results in a large space ratio of the arc area on both sides of the wound battery cell, which leads to low space utilization. In addition, the thickness of the arc area is inconsistent with the thickness of the flat area, resulting in insufficient flatness of the battery cell. In addition, the existing wound battery cells have lithium plating in the arc area, making it difficult to guarantee the quality of the battery cell.
[0003] Therefore, designing a core structure and stack with higher energy density and flatness is of great importance to those skilled in the art. Utility Model Content
[0004] The technical problem to be solved by this utility model embodiment is to provide a core structure and stacked core with higher energy density and higher flatness, so as to solve the problem of insufficient flatness of the battery cell and difficulty in ensuring the quality of the battery cell in the prior art.
[0005] This utility model discloses a wound core structure, which includes: a positive electrode sheet, a negative electrode sheet, and a separator sandwiched between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet, the negative electrode sheet, and the separator are wound to form a wound body. The wound body includes a flat surface region and flat side regions located on both sides of the flat surface region. The surface of the positive electrode sheet within the flat surface region is a positive electrode material region coated with a positive electrode active material, and the portion of the positive electrode sheet within the flat side regions is a positive electrode empty foil region without a positive electrode active material. The portion of the negative electrode sheet within the flat surface region is a negative electrode material region coated with a negative electrode active material, and the portion of the negative electrode sheet within the flat side regions is a negative electrode empty foil region without a negative electrode active material.
[0006] Optionally, an insulating layer is provided in the positive electrode empty foil region.
[0007] Optionally, the insulating layer is a ceramic layer coated within the positive electrode empty foil region.
[0008] Optionally, the distance between the edge of the ceramic layer and the corresponding edge of the positive electrode empty foil region is 0~0.5mm.
[0009] Optionally, the insulating layer is adhesive paper bonded to the positive electrode empty foil area.
[0010] Optionally, the thickness of the insulating layer in the positive electrode empty foil region is less than the thickness of the positive electrode material region.
[0011] Optionally, the positive electrode and the negative electrode are collectively referred to as electrode sheets, and the outermost electrode sheet is provided with an empty foil tail.
[0012] Optionally, the outermost electrode is the positive electrode.
[0013] Optionally, the outermost electrode is the negative electrode.
[0014] To address the problems existing in the prior art, this utility model also provides a stacked core, which includes multiple core structures as described above, and the multiple core structures are stacked together; the core structure further includes a positive electrode tab electrically connected to the positive electrode sheet, and a negative electrode tab electrically connected to the negative electrode sheet; the positive electrode tabs of the multiple core structures are electrically connected, and the negative electrode tabs of the multiple core structures are electrically connected.
[0015] Compared with the prior art, the beneficial effects of the core structure provided by this utility model embodiment are as follows: By designing a core structure, including a positive electrode sheet, a negative electrode sheet, and a separator sandwiched between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet, the negative electrode sheet, and the separator are wound to form a wound body. The wound body includes a flat surface area and flat side areas located on both sides of the flat surface area. The portion of the positive electrode sheet located in the flat side areas is a positive electrode empty foil area without positive electrode active material; the portion of the negative electrode sheet located in the flat side areas is a negative electrode empty foil area without negative electrode active material. By removing the active material from the portions of the positive and negative electrode sheets located in the flat side areas, empty foil areas are formed. On the one hand, this effectively reduces the space ratio of the flat side areas of the core, effectively improves the space utilization rate of the core structure, thereby increasing the energy density of the core structure. On the other hand, it also optimizes the surface flatness of the entire core structure, thereby improving the quality of the core structure. Attached Figure Description
[0016] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings:
[0017] Figure 1 This is a schematic diagram of the core structure provided in this embodiment of the utility model;
[0018] Figure 2 This is a schematic diagram of the structure of the positive electrode sheet provided in this embodiment of the utility model;
[0019] Figure 3 This is a schematic diagram of the negative electrode sheet provided in this embodiment of the utility model;
[0020] Figure 4 This is a schematic diagram of the stacked core structure provided in an embodiment of the present invention.
[0021] The labels for the attached figures are as follows:
[0022] 110. Positive electrode sheet; 120. Negative electrode sheet; 200. Flat surface area; 300. Flat side area; 111. Positive electrode material area; 112. Positive electrode empty foil area; 121. Negative electrode material area; 122. Negative electrode empty foil area; 130. Empty foil tail; 113. Positive electrode tab; 123. Negative electrode tab; 1121. Insulating layer. Detailed Implementation
[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings.
[0024] like Figures 1 to 3 As shown, this utility model provides a specific embodiment of a core structure.
[0025] A core structure, reference Figures 1 to 3 The core structure includes a positive electrode 110, a negative electrode 120, and a separator sandwiched between the positive electrode 110 and the negative electrode 120. The positive electrode 110, the negative electrode 120, and the separator are wound to form a wound body. The wound body includes a surface flat region 200 and side flat regions 300 located on both sides of the surface flat region 200. The surface of the positive electrode 110 within the surface flat region 200 is a positive electrode material region 111 coated with positive electrode active material, and the portion of the positive electrode 110 within the side flat region 300 is a positive electrode empty foil region 112 without positive electrode active material. The portion of the negative electrode 120 within the surface flat region 200 is a negative electrode material region 121 coated with negative electrode active material, and the portion of the negative electrode 120 within the side flat region 300 is a negative electrode empty foil region 122 without negative electrode active material.
[0026] Among them, on the adjacent positive electrode 110 and negative electrode 120 on both sides of the separator, the negative electrode material region 121 needs to be able to cover the adjacent positive electrode material region 111, so as to prevent lithium plating.
[0027] Specifically, refer to Figure 1 The core is a type of wound cell and is the core component of a battery. As the energy storage unit of the battery, it can store electrical energy for later use. When the battery is charging, the cell converts electrical energy into chemical energy for storage. When energy needs to be released, the cell converts the stored chemical energy into electrical energy to supply external devices. The energy storage and release of the core depends on the positive electrode 110 and the negative electrode 120, which are responsible for electron flow and ion transfer.
[0028] Further, refer to Figure 2The surface of the positive electrode 110 within the flat surface region 200 is a positive electrode material region 111 coated with positive electrode active material. The positive electrode active material is used to receive electrons and undergo a reduction reaction. It can be an oxide, such as lithium cobalt oxide, lithium iron phosphate, etc., or lithium manganese oxide, lithium cobalt oxide, etc., to release lithium ions during charging and absorb lithium ions during discharging.
[0029] Further, refer to Figure 3 The portion of the negative electrode 120 within the flat surface region 200 is the negative electrode material region 121, which is coated with a negative electrode active material. The inner surface of the portion of the negative electrode 120 within the flat surface region 200 is coated with a negative electrode active material, which can be graphite, lithium metal, silicon, etc. The negative electrode active material can absorb lithium ions during charging and release lithium ions during discharging. The negative electrode active material works in conjunction with the positive electrode active material to achieve the conversion of electrical energy and chemical energy.
[0030] Existing wound battery cells typically involve directly winding positive and negative electrode sheets coated with active materials and a separator to form a wound body. This results in arc-shaped areas on both sides of the wound body, where the surfaces of the electrode portions are coated with active materials. On one hand, this leads to a large space occupation in the arc-shaped areas on both sides of the battery cell, resulting in low space utilization. On the other hand, during battery charging, the active materials in the arc-shaped areas on both sides of the battery cell are prone to precipitate on the electrode surfaces, leading to lithium plating. Furthermore, the uneven thickness of the arc-shaped areas at both ends of the wound body results in poor flatness of the battery cell, which directly affects the quality of the battery cell.
[0031] In this embodiment, a wound core structure is designed, including a positive electrode 110, a negative electrode 120, and a separator sandwiched between the positive electrode 110 and the negative electrode 120. The positive electrode 110, the negative electrode 120, and the separator are wound to form a wound body. The wound body includes a surface flat region 200 and side flat regions 300 located on both sides of the surface flat region 200. The portion of the positive electrode 110 within the side flat regions 300 is a positive electrode empty foil region 112 that does not contain positive electrode active material; the negative electrode 120... The portion of the positive electrode 110 and negative electrode 120 located within the flat side region 300 is a negative electrode empty foil region 122 without negative electrode active material. The empty foil region is formed by removing the active material from the portions of the positive electrode 110 and negative electrode 120 located within the flat side region 300. On the one hand, this effectively reduces the space ratio of the flat side region of the core and effectively improves the space utilization rate of the core structure, thereby increasing the energy density of the core structure. On the other hand, it also optimizes the surface flatness of the entire core structure, thereby improving the quality of the core structure.
[0032] In one embodiment, reference Figure 1 and Figure 2An insulating layer 1121 is provided in the positive electrode empty foil area 112 of the positive electrode sheet 110. By coating the positive electrode empty foil area 112 of the positive electrode sheet 110 with the insulating layer 1121, direct contact between the positive electrode sheet 110 and the negative electrode sheet 120 can be effectively prevented, thereby avoiding short circuits inside the cell. In addition, the insulating layer 1121 can also prevent the positive electrode active material on the positive electrode sheet 110 from leaking from the edge or surface of the positive electrode sheet 110, thereby improving the safety and stability of the cell.
[0033] In one embodiment, the insulating layer 1121 is a ceramic layer coated in the positive electrode empty foil region 112. Ceramic has excellent insulation properties, which can effectively isolate current and prevent current from flowing on or inside the material, thereby avoiding short circuits and leakage. Ceramic also has good high temperature resistance, which can maintain stability in high temperature environments and is not easily deformed or melted. Furthermore, ceramic has high mechanical strength and hardness, and is not easily broken or deformed.
[0034] When the insulating layer 1121 is a ceramic layer, the distance between the edge of the ceramic layer and the corresponding positive electrode empty foil region 112 is 0~0.5mm.
[0035] In one embodiment, the insulating layer 1121 is adhesive paper bonded to the positive electrode foil area. The adhesive paper is generally soft and flexible, adaptable to various surfaces, easy to wrap and cover to provide good insulation protection, and easy to cut, fold and shape, suitable for various shapes and sizes. Furthermore, compared to materials such as high-performance ceramics, the adhesive paper is less expensive. The adhesive paper itself has certain insulating properties, which can effectively isolate current, prevent short circuits and leakage, and provide basic insulation protection. Some adhesive paper materials are renewable and biodegradable, environmentally friendly, and in line with the concept of sustainable development. More importantly, the adhesive paper has certain shock absorption and cushioning properties, which can reduce the impact of external impacts on the battery or device to a certain extent.
[0036] In one embodiment, reference Figure 1 and Figure 2 The thickness of the insulating layer 1121 is less than the thickness of the positive electrode material region 110; this design is used to ensure the overall flatness of the core structure in order to avoid inconsistent thickness on the surface of the core structure, which would affect the quality of the battery cell.
[0037] In one embodiment, the positive electrode 110 and the negative electrode 120 are collectively referred to as electrodes, and the outermost electrode is provided with an empty foil tail 130. The outermost electrode can be either the positive electrode 110 or the negative electrode 120.
[0038] like Figure 4 As shown, this utility model also provides a specific embodiment of a stacked core.
[0039] A type of stacked core, reference Figure 4 It includes multiple winding core structures 10 as described above, and the multiple winding core structures are stacked; the winding core structure also includes a positive electrode tab 113 electrically connected to the positive electrode sheet 110, and a negative electrode tab 123 electrically connected to the negative electrode sheet 120; the positive electrode tabs 113 of the multiple winding core structures are electrically connected, and the negative electrode tabs 123 of the multiple winding core structures are electrically connected.
[0040] It should be understood that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of this utility model.
Claims
1. A core structure, characterized by, The battery includes a positive electrode sheet, a negative electrode sheet, and a separator sandwiched between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet, the negative electrode sheet, and the separator are wound to form a winding body, the winding body includes a surface flat area and side surface flat areas located on both sides of the surface flat area; the surface of the part of the positive electrode sheet in the surface flat area is a positive electrode material area coated with a positive electrode active material, and the part of the positive electrode sheet in the side surface flat area is a positive electrode empty foil area without positive electrode active material; the part of the negative electrode sheet in the surface flat area is a negative electrode material area coated with a negative electrode active material, and the part of the negative electrode sheet in the side surface flat area is a negative electrode empty foil area without negative electrode active material.
2. The core structure of claim 1, wherein The positive electrode empty foil area is provided with an insulating layer.
3. The core structure of claim 2, wherein The insulating layer is a ceramic layer coated in the positive electrode empty foil area.
4. The core structure of claim 3, wherein The distance between the edge of the ceramic layer and the corresponding edge of the positive electrode empty foil area is 0-0.5mm.
5. The core structure of claim 2, wherein, The insulating layer is a gum paper bonded to the positive electrode empty foil area.
6. The core structure of claim 2, wherein The thickness of the insulating layer in the positive electrode empty foil area is less than the thickness of the positive electrode material area.
7. The core structure of claim 1, wherein The positive electrode sheet and the negative electrode sheet are collectively referred to as electrode sheets, and the outermost electrode sheet is provided with an empty foil tail.
8. The core structure of claim 7, wherein The outermost electrode sheet is the positive electrode sheet.
9. The core structure of claim 7, wherein, The outermost electrode sheet is the negative electrode sheet.
10. A core stack, characterized by The battery includes a plurality of winding core structures as claimed in any one of claims 1-9, and the plurality of winding core structures are stacked; the winding core structure further includes a positive electrode lug electrically connected to the positive electrode sheet and a negative electrode lug electrically connected to the negative electrode sheet; the positive electrode lugs of several winding core structures are electrically connected, and the negative electrode lugs of several winding core structures are electrically connected.