A winding core structure and a lithium ion battery
By setting a first active material layer on the outer side of the negative electrode sheet of the wound battery and providing a first etched area thereon, the lithium plating problem is solved, the cycle stability and energy density of the battery are improved, and the overall performance of the battery is enhanced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENZHEN HIGHPOWER TECH CO LTD
- Filing Date
- 2025-04-29
- Publication Date
- 2026-06-12
Smart Images
Figure CN224355263U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of battery manufacturing technology, specifically relating to a core structure and a lithium-ion battery. Background Technology
[0002] In wound-type battery cells, the negative electrode is typically wound first, followed by the positive electrode. At this point, the outer side (B-side) of the wound negative electrode is wrapped by the positive electrode. Figure 1 Compared to the inner side (A side) of the negative electrode, the arc of the outer side of the winding is larger than that of the positive electrode, resulting in insufficient negative electrode and easy lithium plating, which is not conducive to improving the battery's electrical performance. Utility Model Content
[0003] The technical problem to be solved by this utility model is that lithium plating is prone to occur in the arc area where the negative electrode sheet of the wound battery is wrapped by the positive electrode sheet in the prior art. This utility model provides a core structure and a lithium-ion battery.
[0004] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows:
[0005] A wound core structure is provided, including a positive electrode sheet, a separator, and a negative electrode sheet. The negative electrode sheet includes a negative electrode current collector and an active material layer. The active material layer includes a first active material layer and a second active material layer. The first active material layer and the second active material layer are respectively disposed on both sides of the negative electrode current collector. The first active material layer is located on the outer side of the winding of the negative electrode sheet, and the second active material layer is located on the inner side of the winding of the negative electrode sheet.
[0006] The first active material layer has a first etching region with multiple first etching grooves. The second active material layer may or may not have a second etching region with multiple second etching grooves. The total volume of the multiple first etching grooves in the first etching region is greater than the total volume of the multiple second etching grooves in the second etching region.
[0007] Optionally, the first etching region has a plurality of first etching grooves, and a second etching region is provided on the second active material layer, the second etching region having a plurality of second etching grooves;
[0008] The etching depth of the first etching groove is 5-30 μm, and the etching depth of the second etching groove is 5-20 μm.
[0009] Optionally, the first etching region has a plurality of first etching grooves, and a second etching region is provided on the second active material layer, the second etching region having a plurality of second etching grooves;
[0010] The etching width of the first etching groove is 50-150 μm, and the etching width of the second etching groove is 50-110 μm.
[0011] Optionally, the first etched area has multiple first etched grooves, and no second etched area is provided on the second active material layer;
[0012] The etching depth of the first etching groove is 5-30 μm.
[0013] Optionally, the first etched area has multiple first etched grooves, and no second etched area is provided on the second active material layer;
[0014] The etching width of the first etching groove is 5-150μm.
[0015] Optionally, the depth of the first etching trench is 10%-50% of the thickness of the first active material layer, and the depth of the second etching trench is 10%-30% of the thickness of the second active material layer.
[0016] Optionally, a plurality of the first etching grooves and / or a plurality of the second etching grooves are spaced apart in the length extension direction of the current collector.
[0017] Optionally, a plurality of the first etching grooves and / or a plurality of the second etching grooves are arranged parallel to each other in the length extension direction of the current collector.
[0018] Optionally, the spacing between adjacent first etching grooves is 0.5-3mm, and the spacing between adjacent second etching grooves is 0.5-3mm.
[0019] Optionally, the first etching groove and / or the second etching groove are laser etching grooves.
[0020] On the other hand, this application provides a lithium-ion battery including the aforementioned winding structure.
[0021] The beneficial effects of this application are as follows:
[0022] The core structure provided in this application has a first active material layer in the negative electrode sheet located on the outer side of the negative electrode sheet winding. After placing the first active material layer on the outer side of the negative electrode sheet winding, a first etched area is formed on the first active material layer. The first etched area is beneficial for providing space for lithium ion insertion and accommodation, reducing the lithium plating problem caused by insufficient negative electrode. At the same time, based on solving the lithium plating problem, the outer side of the negative electrode sheet winding has negative electrode active material, which is beneficial for maintaining the energy density of the core. The total volume of the multiple first etched grooves is greater than the total volume of the multiple second etched grooves in the second etched area. This arrangement allows lithium ions to diffuse and insert into the active material more uniformly on the outer side of the negative electrode sheet winding, strengthens the ability of the outer side of the negative electrode sheet winding to cope with lithium plating, reduces the occurrence of lithium plating problems, improves the cycle stability and service life of the battery, and thus enhances the overall performance of the battery. Attached Figure Description
[0023] Figure 1 This is a cross-sectional diagram of a wound battery cell in the existing technology;
[0024] Figure 2 This is a schematic diagram of the negative electrode structure provided in one embodiment of the present invention;
[0025] Figure 3 This is a schematic diagram of the negative electrode structure provided in another embodiment of the present invention.
[0026] The reference numerals in the accompanying drawings are as follows:
[0027] 100. Negative electrode sheet; 1. Negative current collector; 2. Active material layer; 21. First active material layer; 211. First etched region; 2111. First etched trench; 22. Second active material layer; 221. Second etched region; 2211. Second etched trench; H. Etching depth of the first etched trench; H1. Etching depth of the second etched trench; W. Etching width of the first etched trench; W1. Etching width of the second etched trench. Detailed Implementation
[0028] To make the technical problems solved, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.
[0029] In the description of this utility model, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.
[0030] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0031] Reference Figure 2-3 This utility model provides a wound core structure, including a positive electrode sheet, a separator, and a negative electrode sheet 100. The negative electrode sheet 100 includes a negative electrode current collector 1 and an active material layer 2. The active material layer 2 includes a first active material layer 21 and a second active material layer 22. The first active material layer 21 and the second active material layer 22 are respectively disposed on both sides of the negative electrode current collector 1. The first active material layer 21 is located on the outer side of the winding of the negative electrode sheet 100, and the second active material layer 22 is located on the inner side of the winding of the negative electrode sheet 100.
[0032] The first active material layer 21 is provided with a first etching region 211, the first etching region 211 having a plurality of first etching grooves 2111. The second active material layer 22 is provided with or without a second etching region 221, the second etching region 221 having a plurality of second etching grooves 2211. The total volume of the plurality of first etching grooves 2111 in the first etching region 211 is greater than the total volume of the plurality of second etching grooves 2211 in the second etching region 221.
[0033] Specifically, in the core structure provided in this application, the first active material layer 21 in the negative electrode sheet 100 is located on the outer side of the winding of the negative electrode sheet 100. After the first active material layer 21 is placed on the outer side of the winding of the negative electrode sheet 100, a first etched region 211 is formed on the first active material layer 21. The first etched region 211 is beneficial to provide space for lithium ions to be inserted and accommodated, reducing the lithium plating problem caused by insufficient negative electrode. At the same time, based on solving the lithium plating problem, the outer side of the winding of the negative electrode sheet 100 has negative electrode active material, which is beneficial to maintaining the energy density of the core. The total volume of the multiple first etched grooves 2111 is larger than the total volume of the multiple second etched grooves 2211 of the second etched region 221. This arrangement allows lithium ions to diffuse and insert into the active material more uniformly on the outer side of the winding of the negative electrode sheet 100, strengthens the ability of the outer side of the winding of the negative electrode sheet 100 to cope with lithium plating, reduces the occurrence of lithium plating problems, improves the cycle stability and service life of the battery, and thus enhances the overall performance of the battery.
[0034] Reference Figure 3 In one embodiment, the first etched region 211 has a plurality of first etched grooves 2111, and the second active material layer 22 is provided with a second etched region 221, the second etched region 221 having a plurality of second etched grooves 2211;
[0035] The etching depth H of the first etching tank is 5-30 μm, and the etching depth H1 of the second etching tank is 5-20 μm.
[0036] When the etching depth H of the first etching trench is set to 5-30μm, the specific surface area of the active material layer 2 can be effectively increased without destroying the overall structure of the negative electrode current collector 1 and the active material layer 2, providing more insertion sites for lithium ions, thereby better solving the problem of insufficient negative electrode and reducing lithium plating.
[0037] The negative electrode 100 on the inner side of the winding is in better condition than that on the outer side, and does not require excessive etching. An etching depth of 5-30μm can optimize the performance of the active material layer 2 and ensure the overall structure of the negative electrode 100. If the etching depth H1 of the second etching groove is too deep, it will affect the energy density of the battery and may even lead to a decrease in the bonding force between the active material layer 2 and the negative electrode current collector 1, affecting the battery cycle performance. If the etching is too shallow, the etching will not be able to fully play its role in improving battery performance.
[0038] The relatively shallow etching depth of the second etching groove 2211 contrasts with that of the first etching groove 2111, which better reflects the differentiated settings for the different situations of the outer and inner sides of the negative electrode sheet 100 winding. This difference in depth helps to form a reasonable lithium-ion distribution and transport gradient inside the battery, so that lithium ions can move more orderly between the positive and negative electrodes during charging and discharging, balancing the charge and discharge rate and energy density of the core structure, thereby improving the overall performance of the battery.
[0039] The etching depth H of the first etching trench can be 5μm, 8μm, 10μm, 15μm, 20μm or 30μm, and the etching depth H1 of the second etching trench can be 5μm, 8μm, 10μm, 15μm, 20μm or 30μm.
[0040] In one embodiment, the first etched region 211 has a plurality of first etched grooves 2111, and the second active material layer 22 is provided with a second etched region 221, the second etched region 221 having a plurality of second etched grooves 2211;
[0041] The etching width W of the first etching tank is 50-150μm, and the etching width W1 of the second etching tank is 50-110μm.
[0042] Similarly, the outer negative electrode 100 has a longer lithium-ion insertion path due to its winding and wrapping structure, requiring a wider etching trench to increase the specific surface area of the active material layer 2.
[0043] When the etching width W of the first etching trench is 50-150μm, the wider etching trench can shorten the diffusion distance of lithium ions in the first active material layer 21 on the outer side of the winding, reduce the local concentration gradient, and allow more lithium ions to be contained in a unit volume, thus alleviating the problem of insufficient negative electrode.
[0044] Since the positive electrode wrapped by the inner negative electrode sheet 100 is relatively small, the etching width W1 of the second etching groove can be appropriately reduced to avoid excessive etching affecting the energy density of the battery or even weakening the bonding force between the active material layer 2 and the current collector. At the same time, the reasonable matching of the etching width W1 and depth of the first etching groove 2111 and the second etching groove can form a more three-dimensional channel, guiding lithium ions to be evenly distributed inside the battery and improving the overall cycle performance.
[0045] The etching width W of the first etching groove can be 50μm, 70μm, 90μm, 100μm, 120μm, 140μm or 150μm, and the etching width W1 of the second etching groove can be 50μm, 70μm, 90μm, 100μm or 110μm.
[0046] Reference Figure 2 In one embodiment, the first etched region 211 has a plurality of first etched grooves 2111, and no second etched region 221 is provided on the second active material layer 22;
[0047] The etching depth H of the first etching groove is 10-30 μm.
[0048] Because the negative electrode 100 (the surface where the first active material layer 21 is located) is wrapped by the positive electrode, the path for lithium ion insertion and extraction is relatively complex, and the problem of uneven lithium ion distribution and lithium deposition is prone to occur.
[0049] Specifically, since the first active material layer 21 is located on the outer side of the negative electrode 100, lithium ions need to be rapidly inserted and extracted during charging and discharging. The presence of the first etched groove 2111 on the first active material layer 21 can shorten the diffusion path of lithium ions, accelerate the transport speed of lithium ions, and make it easier for lithium ions to migrate from the positive electrode to the first active material layer 21, thereby improving the charging and discharging efficiency of the battery. The second active material layer 22 is located on the inner side of the negative electrode 100, and its dynamics are better than those of the outer side of the negative electrode 100 where the first active material layer 21 is located. Therefore, under the condition that the etching depth H of the first etched groove can improve or solve the lithium plating problem, the second active material layer 22 does not need to be provided with the second etched region 221.
[0050] The etching depth H of the first etching groove can be 10μm, 15μm, 20μm, 20μm or 30μm.
[0051] In one embodiment, the first etched region 211 has a plurality of first etched grooves 2111, and no second etched region 221 is provided on the second active material layer 22;
[0052] The etching width W of the first etching groove is 50-150μm.
[0053] The etching width W of the first etching trench can be 50μm, 70μm, 90μm, 100μm, 120μm, 140μm or 150μm; in conjunction with the above discussion, similarly, under the condition that the etching width of the first etching trench can improve or solve the lithium plating problem, the second etching region 221 may not be provided on the second active material layer 22.
[0054] In one embodiment, the etching depth H of the first etching trench is 10%-50% of the thickness of the first active material layer 21, and the etching depth H of the second etching trench is 10%-30% of the thickness of the second active material layer 22.
[0055] Specifically, the first active material layer 21 is located on the outer side of the negative electrode sheet 100. The depth of the first etching groove is set to 15%-35% of the thickness of the first active material layer 21, which can provide lithium ions with sufficient channels and space for insertion and extraction, increase the contact area between lithium ions and active materials, improve the charging and discharging performance of the battery, and reduce polarization caused by poor lithium ion transport.
[0056] If the etching depth is too deep, exceeding 50%, it may excessively weaken the structural strength of the first active material layer 21, causing problems such as cracking and shedding of the active material layer 2 during the volume change of the battery charging and discharging process, thus affecting the cycle life of the battery. If the etching depth is too shallow, less than 10%, the improvement effect on lithium-ion transport will not be obvious, and the role of the etching groove cannot be fully utilized.
[0057] The etching grooves on the second active material layer 22 mainly assist the first etching groove 2111 in further optimizing the distribution of lithium ions on the entire negative electrode 100. Setting the depth of the second etching groove to 10%-25% of the thickness of the second active material layer 22 can appropriately increase the transport path and reaction sites of lithium ions while ensuring the basic structural integrity of the second active material layer 22, so that the distribution of lithium ions on the inner and outer sides of the negative electrode 100 is more uniform, and the situation of excessively high or low local lithium ion concentration is reduced.
[0058] In one embodiment, a plurality of first etching grooves 2111 and / or a plurality of second etching grooves 2211 are spaced apart in the length extension direction of the current collector.
[0059] Specifically, the multiple first etching grooves 2111 and / or multiple second etching grooves 2211 spaced apart provide multiple uniformly distributed transport channels for lithium ions, enabling lithium ions to be inserted into and extracted from the active material layer 2 in a more orderly and uniform manner along the length of the current collector, thereby improving the charge and discharge efficiency and power performance of the battery.
[0060] The spaced etching grooves along the length of the current collector help ensure relatively consistent lithium-ion transport at different locations inside the battery. This allows lithium-ions to react with the active material through the spaced etching grooves, resulting in a more balanced charge and discharge state across the battery. This, in turn, improves the overall consistency and stability of the battery, enhancing the performance and lifespan of the battery pack.
[0061] In one embodiment, a plurality of first etching grooves 2111 and / or a plurality of second etching grooves 2211 are arranged parallel to each other in the length extension direction of the current collector.
[0062] Specifically, the parallel arrangement of the etching grooves can provide a clear and regular transport direction for lithium ions, enabling lithium ions to be orderly inserted into and extracted from the active material layer 2 along the parallel etching grooves in the length direction of the current collector. This reduces the disordered diffusion of lithium ions during transport, improves the efficiency and accuracy of lithium ion transport, and helps to improve the charge and discharge performance of the battery.
[0063] In addition, the parallel etching grooves help to form a relatively uniform electric field distribution on the current collector. During the charging and discharging process of the battery, the uniform electric field can make lithium ions be subjected to a more consistent force along the entire length of the current collector, thereby distributing them more evenly in the active material layer 2, avoiding local lithium ion concentrations that are too high or too low, and further improving the charging and discharging efficiency and cycle stability of the battery.
[0064] In one embodiment, the spacing between adjacent first etching grooves 2111 is 0.5-3 mm, and the spacing between adjacent second etching grooves is 0.5-3 mm.
[0065] Specifically, if the spacing between adjacent first etching trenches 2111 is too small, the first active material layer 21 may become too thin after etching, making it prone to breakage and detachment during battery charging and discharging, affecting battery performance and lifespan. Furthermore, a small spacing increases the difficulty and cost of the etching process. If the spacing is too large, exceeding 3mm, the lithium-ion transport path in the active material layer 2 may be too long, hindering rapid lithium-ion transport and reaction, thus reducing battery charging and discharging efficiency. When the spacing between adjacent second etching trenches 2211 is less than 0.5mm, the second active material layer 22 may be affected by overly dense etching, impacting its bonding with the current collector and its structural stability, leading to active material peeling during battery cycling. Conversely, when the spacing is greater than 3mm, the guiding and regulating effect of the second etching trenches 2211 on lithium-ion transport weakens, failing to effectively assist the first etching trenches 2111 in optimizing lithium-ion distribution throughout the electrode, potentially resulting in uneven lithium-ion distribution on the electrode surface and affecting overall battery performance.
[0066] In one embodiment, the first etching groove 2111 and / or the second etching groove 2211 are laser etching grooves.
[0067] Laser etching technology can precisely control the size, shape, and position of the etching grooves. When manufacturing the battery negative electrode sheet 100, the first etching groove 2111 and the second etching groove 2211 that meet the requirements can be precisely etched according to the battery design requirements, ensuring the consistency of the depth, width, and spacing of the etching grooves. This is beneficial for further optimizing the lithium-ion transport path inside the battery and improving the stability of battery performance.
[0068] In one embodiment, the negative electrode 100 also has a flat portion, and the first etching area 211 and the second etching area 221 are also provided at the flat portion. Therefore, when processing the first etching area 211 and the second etching area 221 at the winding position of the negative electrode, the equipment does not need complex angle adjustment and surface adaptation. The same first etching area 211 and second etching area 221 can be directly set at the flat portion, making the production process more convenient and efficient.
[0069] On the other hand, another embodiment of this application provides a lithium-ion battery including the aforementioned winding structure.
[0070] The lithium-ion battery provided in this application includes the aforementioned core structure. In the core structure, the first active material layer 21 of the negative electrode 100 is located on the outer side of the winding of the negative electrode 100. After the first active material layer 21 is located on the outer side of the winding of the negative electrode 100, a first etched region 211 is formed on the first active material layer 21. The first etched region 211 is beneficial for providing space for lithium ion insertion and accommodation, reducing the lithium plating problem caused by insufficient negative electrode. At the same time, based on solving the lithium plating problem, the second active material layer 22 does not have a second etched region 221, or the second active material layer 22 has a second etched region 221, and the second etched region 221... The total volume of the plurality of second etching grooves 2211 in the second etching region 211 is smaller than the total volume of the plurality of first etching grooves 2111 in the first etching region 211, reducing the amount of active material etched in the negative electrode 100, thereby helping to maintain the energy density of the core. The total volume of the plurality of first etching grooves 2111 is larger than the total volume of the plurality of second etching grooves 2211 in the second etching region 221. This arrangement allows lithium ions to diffuse and embed more uniformly in the active material on the outer side of the negative electrode 100 winding, strengthening the ability of the outer side of the negative electrode 100 winding to cope with lithium plating, reducing the occurrence of lithium plating problems, improving the cycle stability and lifespan of the battery, thereby enhancing the overall performance of the battery. The present invention will be further described below through embodiments.
[0071] Example 1
[0072] This embodiment illustrates the core structure and lithium-ion battery disclosed in this utility model, including:
[0073] The negative electrode sheet after roll forming is laser etched. The etching depth of the first etching groove is 40% of the thickness of the first active material layer, the etching depth of the second etching groove is 30% of the thickness of the second active material layer, the spacing between adjacent first etching grooves is 1.5 mm, and the spacing between adjacent second etching grooves is 1.5 mm.
[0074] The positive electrode, separator, and the aforementioned negative electrode are assembled into a lithium-ion battery.
[0075] Comparative Example 1
[0076] This comparative example is used to illustrate the core structure and lithium-ion battery disclosed in this utility model, including most of the operations in Example 1, with the following differences:
[0077] The etching depth of the first etching trench is 40% of the thickness of the first active material layer, and the etching depth of the second etching trench is 40% of the thickness of the second active material layer.
[0078] Comparative Example 2
[0079] This comparative example is used to illustrate the core structure and lithium-ion battery disclosed in this utility model, including most of the operations in Example 1, with the following differences:
[0080] The etching depth of the first etching trench is 30% of the thickness of the first active material layer, and the etching depth of the second etching trench is 30% of the thickness of the second active material layer.
[0081] Comparative Example 3
[0082] This comparative example is used to illustrate the core structure and lithium-ion battery disclosed in this utility model, including most of the operations in Example 1, with the following differences:
[0083] The etching depth of the first etching trench is 30% of the thickness of the first active material layer, and the etching depth of the second etching trench is 40% of the thickness of the second active material layer.
[0084] Performance tests were conducted on Example 1 and Comparative Examples 1-3 as described above:
[0085] The battery was charged and discharged using different currents:
[0086] 20 cycles of 1C charge / 0.5C, 2C charge / 0.5C, and 3C charge / 0.5C charge / discharge.
[0087] Table 1
[0088]
[0089] As shown in Table 1, no lithium plating problem occurred in the charge-discharge tests of Example 1 and Comparative Example 1. Comparative Example 2 and Comparative Example 3 also did not exhibit lithium plating at the first two charge-discharge rates, but slight lithium plating occurred at 3C charge / 0.5C charge-discharge for 20 cycles. This indicates that the core structure designed in this invention can effectively suppress lithium plating problem under appropriate etching depth settings (such as Example 1 and Comparative Example 1). Compared with the comparative examples, Example 1 and Comparative Example 1 have better stability in handling high-rate charge-discharge. However, due to the deeper etching depth of the second etching groove in Comparative Example 1, the energy density is low.
[0090] Although Comparative Example 2 has the highest energy density, it has a slight lithium plating problem. In contrast, Example 1 has a high energy density even without lithium plating. This shows that the core structure of this invention can maintain a good energy density level while ensuring battery safety (no lithium plating), thus achieving a balance between safety and energy density.
[0091] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A core structure, characterized in that, The device includes a positive electrode, a separator, and a negative electrode (100). The negative electrode (100) includes a negative current collector (1) and an active material layer (2). The active material layer (2) includes a first active material layer (21) and a second active material layer (22). The first active material layer (21) and the second active material layer (22) are respectively disposed on both sides of the negative current collector (1). The first active material layer (21) is located at least on the outer side of the winding of the negative electrode (100), and the second active material layer (22) is located at least on the inner side of the winding of the negative electrode (100). The first active material layer (21) is provided with a first etching region (211), the first etching region (211) has a plurality of first etching grooves (2111), the second active material layer (22) is provided with or not provided with a second etching region (221), the second etching region (221) has a plurality of second etching grooves (2211), and the total volume of the plurality of first etching grooves (2111) of the first etching region (211) is greater than the total volume of the plurality of second etching grooves (2211) of the second etching region (221).
2. The core structure according to claim 1, characterized in that, The first etched area (211) has a plurality of first etched grooves (2111), and a second etched area (221) is provided on the second active material layer (22), and the second etched area (221) has a plurality of second etched grooves (2211). The etching depth (H) of the first etching tank is 5-30 μm, and the etching depth (H1) of the second etching tank is 5-20 μm.
3. The core structure according to claim 1, characterized in that, The first etched area (211) has a plurality of first etched grooves (2111), and a second etched area (221) is provided on the second active material layer (22), and the second etched area (221) has a plurality of second etched grooves (2211). The etching width (W) of the first etching tank is 50-150 μm, and the etching width (W1) of the second etching tank is 50-110 μm.
4. The core structure according to claim 1, characterized in that, The first etched area (211) has multiple first etched grooves (2111), and the second active material layer (22) does not have a second etched area (221). The etching depth (H) of the first etching groove is 5-30 μm.
5. A core structure according to claim 1, characterized in that, The first etched area (211) has multiple first etched grooves (2111), and the second active material layer (22) does not have a second etched area (221). The etching width (W) of the first etching groove is 50-150 μm.
6. A core structure according to claim 1, characterized in that, The etching depth (H) of the first etching trench is 10%-50% of the thickness of the first active material layer (21), and the etching depth (H1) of the second etching trench is 10%-30% of the thickness of the second active material layer (22).
7. A core structure according to claim 1, characterized in that, A plurality of first etching grooves (2111) and / or a plurality of second etching grooves (2211) are spaced apart in the length extension direction of the current collector; A plurality of first etching grooves (2111) and / or a plurality of second etching grooves (2211) are arranged parallel to each other in the length extension direction of the current collector.
8. A core structure according to claim 7, characterized in that, The spacing between adjacent first etching grooves (2111) is 0.5-3mm, and the spacing between adjacent second etching grooves (2211) is 0.5-3mm.
9. A core structure according to claim 1, characterized in that, The negative electrode (100) includes a flat portion, and the flat portion is provided with a first etched area (211) and a second etched area (221).
10. A lithium-ion battery, characterized in that, Includes the core structure as described in any one of claims 1-9.