Electrode plate and battery cell
By employing different compaction structure designs on the battery electrodes, the problem of stress imbalance on the concave and convex surfaces of the electrodes during battery winding was solved, improving the battery's dynamic performance and cycle life, and optimizing the battery's energy density and fast charging performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- 江苏远航锦锂新能源科技有限公司
- Filing Date
- 2025-05-12
- Publication Date
- 2026-04-21
AI Technical Summary
In the existing technology, during the battery winding process, the existing technology cannot effectively solve the problem of active material shedding and battery cycle life caused by the stress imbalance of the uneven surface of the electrode.
The positive and negative electrode sheets are designed with different compaction structures on both sides. By setting high compaction density and low compaction density material layers, an opposite electrode structure is formed, which enhances the wettability of the electrode sheets.
It improves the battery's dynamic performance and cycle life, solves the problem of active material shedding caused by stress imbalance on the uneven surface of the electrode, and optimizes the battery's energy density and fast charging performance.
Smart Images
Figure CN224153366U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of electrode processing technology, and in particular to an electrode sheet and a battery cell. Background Technology
[0002] With the rapid development of new energy vehicles in recent years, higher demands have been placed on battery energy density and lifespan to alleviate range anxiety for consumers. Current technologies offer numerous methods to improve battery energy density, with innovative solutions emerging in battery system structure and cell design.
[0003] Currently, battery cell design primarily utilizes high-capacity, high-compaction materials, matched with high coating density, and generally employs an identical A and B side design. However, the increased electrode surface density and compaction density lead to increased internal stress on the concave surface of the electrode, especially in cylindrical wound cells. During winding, the curvature differences between the concave and convex surfaces of the electrode and during charging and discharging result in increased internal stress on the concave surface. This leads to poorer contact and adhesion between the active material, conductive agent, binder, and current collector in the two surface areas of the electrode, thus affecting battery cycle life. Currently, no effective solution has been proposed to address these issues. Utility Model Content
[0004] Purpose of the utility model: To provide an electrode sheet and a battery cell to at least solve one of the problems existing in the prior art.
[0005] Technical solution: An electrode sheet, comprising:
[0006] Positive electrode sheet,
[0007] The positive electrode includes a first conductive substrate, and a first material layer and a second material layer respectively disposed on the surface of the first conductive substrate; and
[0008] The negative electrode is disposed opposite to the positive electrode.
[0009] The negative electrode sheet includes a second conductive substrate, and a third material layer and a fourth material layer respectively disposed on the surface of the second conductive substrate;
[0010] The compaction density of the first material layer is greater than that of the second material layer, and the compaction density of the third material layer is less than that of the fourth material layer, so that the two sides of the positive electrode and the negative electrode have different compaction structures.
[0011] Preferably, the compacted area of the first powder layer of the first material layer is greater than the compacted area of the second powder layer of the second material layer.
[0012] Preferably, the compacted area of the first powder layer is 0.02-0.1 g / m² larger than that of the second powder layer. 3 .
[0013] Preferably, the compacted area of the third powder layer of the third material layer is smaller than the compacted area of the fourth powder layer of the fourth material layer.
[0014] Preferably, the first material layer is a first active substance layer, and the specific capacity of the first active substance layer is 145-150 mAh / g.
[0015] Preferably, the compaction density of the first powder layer of the first material layer is 2.55-2.65 g / m³. 3 The compacted density of the second powder layer of the second material layer is 2.45-2.55 g / m³. 3 .
[0016] Preferably, the second material layer is a second active material layer, and the specific capacity of the second active material layer is 140-145 mAh / g.
[0017] Preferably, the third material layer is a third active substance layer, and the specific capacity of the third active substance layer is 340-350 mAh / g; the compaction density of the third powder layer of the third material layer is 1.45-1.55 g / m³. 3 .
[0018] Preferably, the fourth material layer is a fourth active substance layer, and the specific capacity of the fourth active substance layer is 350-355 mAh / g; the compaction density of the fourth powder layer of the fourth material layer is 1.55-1.65 g / m³. 3 .
[0019] To achieve the above objectives, according to another aspect of this application, a battery cell is also provided.
[0020] The battery cell according to this application includes the aforementioned electrode plates;
[0021] It also includes: a separator, which is disposed between the positive electrode and the negative electrode, and the positive electrode, the separator and the negative electrode are stacked in sequence and wound in a preset direction to obtain a core.
[0022] Beneficial Effects: In this embodiment, different compaction structures are used. The compaction density of the first material layer is greater than that of the second material layer, and the compaction density of the third material layer is less than that of the fourth material layer. This results in different compaction structures on both sides of the positive and negative electrode sheets, enhancing the wettability of the electrode sheets. This improves the battery's dynamic performance and cycle life. Furthermore, it solves the current problem in cell design, which primarily uses high-capacity, high-compact materials with high coating density, and generally employs identical A and B sides. The increased surface density and compaction density of the electrode sheets lead to increased internal stress on the concave surfaces, especially in cylindrical wound cells. During winding, the concave and convex surfaces of the electrode sheet exhibit curvature differences during winding and cell charging / discharging, resulting in increased internal stress on the concave surfaces. This leads to poorer contact and adhesion between the active materials, conductive agents, binders, and current collectors on both sides of the electrode sheet, thus affecting the battery's cycle life. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the planar structure of the positive electrode of this utility model.
[0024] Figure 2 This is a schematic diagram of the negative electrode sheet planar structure of the electrode sheet of this utility model;
[0025] Figure 3 This is a schematic diagram of the planar structure of the electrode sheet of this utility model; and
[0026] Figure 4 This is a schematic diagram of the planar structure of the battery cell part of this utility model.
[0027] The attached figures are labeled as follows:
[0028] 10. Positive electrode sheet; 101. First conductive substrate; 102. First material layer; 103. Second material layer;
[0029] 20. Negative electrode sheet; 201. Second conductive substrate; 202. Third material layer; 203. Fourth material layer;
[0030] 30. Diaphragm. Detailed Implementation
[0031] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0033] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.
[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0035] like Figure 1-4 As shown, this application relates to an electrode sheet and a battery cell. Figure 1-3 As shown, the electrode includes a positive electrode 10, which is mainly used to store and release lithium ions. The positive electrode material undergoes intercalation and deintercalation reactions with lithium ions during the battery charging and discharging process.
[0036] The positive electrode 10 includes a first conductive substrate 101, and a first material layer 102 and a second material layer 103 respectively disposed on the surface of the first conductive substrate 101;
[0037] Specifically, the first conductive substrate 101 is typically an aluminum foil, serving as a current collector and an electron transport channel;
[0038] First material layer 102 (high compaction density layer): coated on one side of the first conductive substrate 101, with high compaction density and closely arranged active material particles.
[0039] Second material layer 103 (low compaction density layer): coated on the other side of the first conductive substrate 101, with low compaction density and high porosity.
[0040] The negative electrode 20 is disposed opposite to the positive electrode 10. The negative electrode 20 includes a second conductive substrate 201 and a third material layer 202 and a fourth material layer 203 respectively disposed on the surface of the second conductive substrate 201.
[0041] Specifically, the negative electrode 20 is mainly used to receive and release lithium ions; the negative electrode material absorbs lithium ions during charging and releases them during discharging.
[0042] The second conductive substrate 201 is typically copper foil.
[0043] Third material layer 202 (low compaction density layer): has a low compaction density and a loose structure.
[0044] Fourth material layer 203 (high compaction density layer): High compaction density (e.g., 1.6-1.8 g / cm³) 3 ), with dense particles.
[0045] The compaction density of the first material layer 102 is greater than that of the second material layer 103, and the compaction density of the third material layer 202 is less than that of the fourth material layer 203, so that the two sides of the positive electrode 10 and the negative electrode 20 have different compaction structures. By setting the high-density layer (first layer) of the positive electrode and the low-density layer (third layer) of the negative electrode opposite to each other, a double-sided electrode structure with different compaction densities is formed.
[0046] This application adopts a novel electrode structure to solve the problems of uneven stress on the concave and convex surfaces of the electrode and the increasing stress difference within the electrode as the cycle time increases, which leads to the shedding of active material and even electrode breakage. In addition, the different compaction design of the concave and convex surfaces can enhance the wettability of the electrode, thereby improving the battery dynamic performance and cycle life.
[0047] As can be seen from the above description, this application achieves the following technical effects:
[0048] In this embodiment, different compaction structures are used. The compaction density of the first material layer 102 is greater than that of the second material layer 103, and the compaction density of the third material layer 202 is less than that of the fourth material layer 203. This results in different compaction structures on the two sides of the positive electrode 10 and the negative electrode 20, thereby enhancing the wettability of the electrode and improving the battery's dynamic performance and cycle life. This solves the current problem in cell design, which mainly uses high-capacity, high-compact materials and high coating density, and basically adopts the same design for both sides. Due to the increase in electrode surface density and compaction density, the internal stress of the concave surface of the electrode increases, especially in cylindrical wound cells. During the winding process, the concave and convex surfaces of the electrode have different curvatures during winding and cell charging and discharging, resulting in increased internal stress on the concave surface of the electrode. This leads to poorer contact and adhesion between the active material, conductive agent, binder, and current collector in the two surface areas of the electrode, thus affecting the battery's cycle life.
[0049] Furthermore, the compacted area of the first powder layer of the first material layer 102 is greater than the compacted area of the second powder layer of the second material layer 103. It can be understood that the powder layer (active material + conductive agent, etc.) in the first material layer 102 has a larger load per unit area, meaning its coating is thicker or its density is higher; the positive electrode 10 employs a two-sided asymmetric structure, with one side loading more active material to provide stronger energy output.
[0050] The high areal density layer (first layer) prioritizes the electron transport requirements during high-rate charging and discharging; the low areal density layer (second layer) reserves pores to alleviate the bottleneck of lithium-ion diffusion.
[0051] Furthermore, the compacted area of the first powder layer is 0.02-0.1 g / m² larger than that of the second powder layer. 3 Understandably, this enables precise structural control, balancing local stress and temperature rise within the battery cell, and optimizing the wettability and reaction rate between the electrodes and the electrolyte.
[0052] Furthermore, the compacted area of the third powder layer of the third material layer 202 is smaller than the compacted area of the fourth powder layer of the fourth material layer 203. It can be understood that the asymmetric structure on the negative electrode corresponds to that on the positive electrode; the negative electrode side is more porous (smaller compacted area), which helps to buffer the volume expansion during lithium-ion insertion. This can reduce powder shedding or debinding caused by negative electrode expansion, extend cycle life, and improve morphological stability under fast charging performance.
[0053] Furthermore, the first material layer 102 is a first active material layer, and the specific capacity of the first active material layer is 145-150 mAh / g. It can be understood that this is primarily a positive electrode active material for energy storage, such as a high-nickel ternary NCM or NCA, providing a higher theoretical capacity.
[0054] Preferably, the first active material layer includes, but is not limited to, one of: lithium nickel manganese cobalt oxide, lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium titanate, and lithium nickel oxide. This allows for the selection of a variety of materials.
[0055] Furthermore, the compaction density of the first powder layer of the first material layer 102 is 2.55-2.65 g / m³. 3 The compacted density of the second powder layer of the second material layer is 2.45-2.55 g / m³. 3 Understandably, the ability to offer a variety of compaction densities allows for flexible use and ultimately enhances market competitiveness.
[0056] Furthermore, the second material layer 103 is a second active material layer, and the specific capacity of the second active material layer is 140-145 mAh / g. It is understood that this can reduce the side reaction rate between this layer and the electrolyte, helping to improve long-term stability, while also enabling flexible selection.
[0057] Preferably, the second active material layer includes, but is not limited to, one of: lithium nickel manganese cobalt oxide, lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium titanate, and lithium nickel oxide. This allows for the selection of a variety of materials.
[0058] Furthermore, the third material layer 202 is a third active material layer, and the specific capacity of the third active material layer is 340-350 mAh / g; the compaction density of the third powder layer of the third material layer 202 is 1.45-1.55 g / m³. 3 Understandably, this layer is a negative electrode material (such as graphite or graphite with a small amount of silicon doping), providing high capacity but low density; the low compaction density retains a certain amount of porosity, which helps to alleviate the volume expansion caused by lithium-ion intercalation.
[0059] Furthermore, the fourth material layer 203 is a fourth active material layer, and the specific capacity of the fourth active material layer is 350-355 mAh / g; the compaction density of the fourth powder layer of the fourth material layer 203 is 1.55-1.65 g / m³. 3 Understandably, this is the other side of the negative electrode, with higher specific capacity and denser compaction, designed as a high-load and dense surface to support high-rate discharge or provide volumetric energy density.
[0060] like Figure 4As shown, this application also relates to a battery cell, characterized in that it includes the aforementioned electrode plates;
[0061] It also includes a diaphragm 30, which is disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the diaphragm 30, and the negative electrode 20 are stacked sequentially and wound in a preset direction to obtain a core. This achieves good forming effect and is easy to implement and operate.
[0062] The following examples further illustrate this point:
[0063] A battery electrode sheet, wherein the first material layer (A side) of the positive electrode sheet has an active material specific capacity of 146 mAh / g and a first powder layer with a compaction of 2.6 g / m3; the second material layer (B side) has an active material specific capacity of 143 mAh / g and a second powder layer with a compaction of 2.55 g / m3; the active material, conductive agent, and binder are mixed and coated onto both sides of the first conductive substrate (positive electrode current collector) in a ratio of 97%:1.5%:1.5%.
[0064] The third material layer (A side) of the negative electrode sheet has a specific capacity of 348 mAh / g for the active material 202 and a compaction density of 1.52 g / m3 for the third powder layer. The fourth material layer (B side) has a specific capacity of 352 mAh / g for the active material 203 and a compaction density of 1.62 g / m3 for the fourth powder layer. The active material, conductive agent, binder, and thickener are mixed and coated onto both sides of the second conductive substrate (negative electrode current collector) in a ratio of 96.8%:1.2%:0.8%:1.2%.
[0065] The above-mentioned electrode sheets are rolled and pressed, and then the A side of the positive electrode sheet is aligned with the B side of the negative electrode sheet. They are separated by a separator and wound to obtain a core. After the core is put into the shell, baked, injected with electrolyte, and formed, a lithium-ion battery is obtained.
[0066] This application has the following beneficial effects:
[0067] 1. By adopting different compaction structures on the A and B sides of the electrode, the problem of excessive internal stress and easy delamination caused by the difference in curvature on both sides of the electrode after winding is solved, thereby improving the cycle life of the battery.
[0068] Because of the difference in hole porosity between A and B, the hole porosity of the side with greater compaction is relatively smaller, and the hole porosity of the side with less compaction is relatively larger. This can optimize the wetting effect of the inner ring of the electrode and improve battery performance.
[0069] 2. Improved interface contact and electron / ion transport path: High compaction layer provides higher electron conductivity; Low compaction layer has better porosity, which is conducive to electrolyte wetting and lithium ion diffusion; Forming a "dense-porous complementary structure" to improve rate performance and charge / discharge efficiency.
[0070] 3. Optimize the balance between electrochemical performance and energy density. The optimization of the internal structure enables the battery to maintain good fast charging performance while ensuring high energy density.
[0071] 4. Enhanced safety: Different compaction layers can provide different buffering or thermal diffusion effects during short circuits or overcharging; the high porosity on the low compaction side helps to alleviate pressure buildup caused by thermal expansion.
[0072] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and all such equivalent transformations fall within the protection scope of the present invention.
Claims
1. An electrode tab, characterized by include: Positive electrode plate (10), The positive electrode (10) includes a first conductive substrate (101), a first material layer (102) and a second material layer (103) respectively disposed on the surface of the first conductive substrate (101); and The negative electrode (20) is disposed opposite to the positive electrode (10) on opposite sides. The negative electrode sheet (20) includes a second conductive substrate (201), and a third material layer (202) and a fourth material layer (203) respectively disposed on the surface of the second conductive substrate (201); The compaction density of the first material layer (102) is greater than that of the second material layer (103), and the compaction density of the third material layer (202) is less than that of the fourth material layer (203), so that the two sides of the positive electrode (10) and the negative electrode (20) have different compaction structures.
2. The electrode patch of claim 1, wherein, The compacted area of the first powder layer of the first material layer (102) is greater than the compacted area of the second powder layer of the second material layer (103).
3. The electrode panel of claim 2, wherein, The first powder layer compaction area is 0.02-0.1 g / m larger than the second powder layer compaction area 3 .
4. The electrode patch of claim 1, wherein, The compacted area of the third powder layer of the third material layer (202) is smaller than the compacted area of the fourth powder layer of the fourth material layer (203).
5. The electrode patch of claim 1, wherein, The first material layer (102) is a first active material layer, and the specific capacity of the first active material layer is 145-150mAh / g.
6. The electrode patch of claim 1, wherein, The first powder layer of the first material layer (102) has a compacted density of 2.55-2.65 g / m 3 ; the second powder layer of the second material layer (103) has a compacted density of 2.45-2.55 g / m 3 .
7. The electrode patch of claim 1, wherein, The second material layer (103) is a second active material layer, and the specific capacity of the second active material layer is 140-145 mAh / g.
8. The electrode patch of claim 1, wherein, The third material layer (202) is a third active material layer, the gram capacity of the third active material layer is 340-350 mAh / g; the third powder layer compaction density of the third material layer (202) is 1.45-1.55 g / m 3 .
9. The electrode patch of claim 1, wherein, The fourth material layer (203) is a fourth active material layer, the gram capacity of the fourth active material layer is 350-355 mAh / g; the fourth powder layer compaction density of the fourth material layer (203) is 1.55-1.65 g / m 3 .
10. An electric cell, characterized by Includes the electrode plates as described in any one of claims 1-9; It also includes a diaphragm (30), which is disposed between the positive electrode (10) and the negative electrode (20), and the positive electrode (10), the diaphragm (30) and the negative electrode (20) are stacked in sequence and wound in a preset direction to obtain a core.