Battery pole piece and battery roll core

Abstract

The utility model discloses a battery pole piece and a battery roll core. The battery pole piece comprises a current collector; the active coating comprises a first coating section and a second coating section which are arranged on the current collector, and the first coating section can be positioned on the outer side of the second coating section when the battery pole piece is wound; and the first groove is formed in the first coating section. In the application, the first groove is formed in the first coating section, and different areas of the battery pole piece are differentially arranged in combination with actual application, so that the first groove is prevented from deforming and collapsing, and the first groove is ensured to improve the flowing speed of an electrolyte, the infiltration effect on the battery pole piece and the liquid storage capacity of the battery pole piece; the contact reaction area of the active coating of the battery pole piece is increased, and extrusion caused by expansion of the battery pole piece is relieved, so that the cycle and fast charge performance of the battery is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery electrode and a battery core. Background Technology

[0002] With the development of the new energy era, the rapid development of lithium batteries has followed. In recent years, lithium batteries have been widely used in electronic devices such as mobile phones and tablets, and hybrid vehicles and new energy electric vehicles have gradually become popular in people's lives, leading to higher demands on the performance of lithium batteries. Therefore, high-performance lithium-ion rechargeable batteries with large capacity, high energy density, and the ability to meet fast charging and discharging requirements have received widespread attention. At the same time, the safety of lithium batteries has also become a major concern. During long-term use, the battery electrodes will expand, causing compression and resulting in the electrolyte accumulating on both sides of the battery electrodes. This leads to lithium deposition at the edges of the battery electrodes, and the obstructed electrolyte return can cause the center of the battery electrodes to burn due to insufficient electrolyte, thus negatively impacting the battery's cycle life and fast charging performance.

[0003] Although existing technologies propose to improve the wettability of the electrolyte and the electrolyte storage capacity of the electrode by setting groove structures on the surface of the battery electrode, in practical applications, after the battery electrode is wound into a battery core, the stress in the area near the center of the battery core is significantly greater than that in the area away from the center of the battery core. This causes uneven stress on the groove structure, resulting in deformation and collapse inside the groove structure. Therefore, it cannot effectively improve the battery's cycle and fast charging performance in practical applications. Utility Model Content

[0004] This application provides a battery electrode sheet that allows for differentiated settings of different areas of the battery electrode sheet according to actual applications, effectively preventing the first groove from deforming and collapsing due to uneven force, thereby effectively improving the cycle and fast charging performance of the battery in practical applications.

[0005] A battery electrode sheet according to an embodiment of this application includes: a current collector; an active coating, the active coating including a first coating segment and a second coating segment arranged on the current collector, wherein the first coating segment is located outside the second coating segment when the battery electrode sheet is wound; and a first groove disposed on the first coating segment.

[0006] In this battery electrode, the first coating section is wound around the outside of the second coating section to reduce the stress on the first coating section compared to the second coating section. Furthermore, the first groove is formed on the first coating section, allowing for differentiated settings for different areas of the battery electrode based on actual applications. This effectively prevents deformation and collapse of the first groove due to uneven stress, ensuring that the first groove can improve the electrolyte flow rate, the electrolyte wetting effect on the battery electrode, and the electrolyte storage capacity of the battery electrode in practical applications. It also increases the contact reaction area of ​​the active coating on the battery electrode, alleviates the compression caused by the expansion of the battery electrode, and thus improves the battery's cycle and fast-charging performance.

[0007] According to some embodiments of this application, a second groove extending along the mechanical stretching direction is also included, the second groove being disposed on the second coating section.

[0008] According to some embodiments of this application, the current collector has two oppositely arranged sides, and the second coating segment includes a second base coating and a second top coating, wherein: the second base coating is disposed on at least one of the sides, the second top coating is stacked on the second base coating, and the second groove is disposed on the second top coating.

[0009] According to some embodiments of this application, the first coating segment includes a first base coating and a first top coating, the first base coating is disposed on at least one of the said side surfaces, the first top coating is stacked on the first base coating, and the first groove is disposed on the first top coating.

[0010] According to some embodiments of this application, the proportion of the second groove on any side of the current collector is R1; the expression for R1 is: Where a1 is the length of the second groove, b1 is the width of the second groove, d1 is the depth of the second groove, n1 is the number of the second grooves on any side of the current collector, M is the weight of the active coating on any side of the current collector, X is the length of the second coating section, and S is the length of the current collector.

[0011] According to some embodiments of this application, 0 ≤ R1 ≤ 10%.

[0012] According to some embodiments of this application, the proportion of the first groove on any side of the current collector is R2; the expression for R2 is: Where a2 is the length of the first groove, b2 is the width of the first groove, d2 is the depth of the first groove, and n2 is the number of the first grooves on any side of the current collector.

[0013] Based on the same inventive concept, this application also proposes a battery core, comprising: a separator and two battery electrodes as described above, wherein the active coating in one of the battery electrodes is composed of a first active material, and the active coating in the other battery electrode is composed of a second active material; the separator is disposed between the two battery electrodes to separate the two battery electrodes.

[0014] According to some embodiments of this application, the length of the second coating segment is expressed as follows: Where x is the thickness of any of the battery electrodes, y is the thickness of the other battery electrode, z is the thickness of the separator, r is the diameter of the winding needle, and m is the number of turns of the second coating section.

[0015] According to some embodiments of this application, 1 ≤ m ≤ 50.

[0016] In summary, the battery electrode provided in this application has the following technical effects:

[0017] The first coating section is wound around the outside of the second coating section to reduce the stress on the first coating section compared to the second coating section. Furthermore, the first groove is formed on the first coating section, allowing for differentiated settings for different areas of the battery electrode sheet based on practical applications. This effectively prevents deformation and collapse of the first groove due to uneven stress, ensuring that the first groove can improve the electrolyte flow rate, the electrolyte wetting effect on the battery electrode sheet, and the electrolyte storage capacity of the battery electrode sheet in practical applications. It also increases the contact reaction area of ​​the active coating on the battery electrode sheet, alleviates the compression caused by the expansion of the battery electrode sheet, and thus improves the battery's cycle and fast-charging performance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the planar structure of the battery electrode sheet according to an embodiment of this application;

[0019] Figure 2 This is a schematic diagram of the structure of the battery electrode sheet according to an embodiment of this application;

[0020] Figure 3 This is a schematic diagram of the structure of a type one battery electrode according to an embodiment of this application;

[0021] Figure 4 This is a schematic diagram of the structure of a second type of battery electrode according to an embodiment of this application;

[0022] Figure 5 This is a schematic diagram of the structure of the battery electrode of type three according to an embodiment of this application;

[0023] Figure 6This is a schematic diagram of the structure of a fourth type of battery electrode according to an embodiment of this application;

[0024] Figure 7 This is a schematic diagram of the structure of a fifth type of battery electrode according to an embodiment of this application;

[0025] Figure 8 This is a schematic diagram of the structure of a sixth type of battery electrode according to an embodiment of this application;

[0026] Figure 9 This is a schematic diagram of the structure of a seventh type of battery electrode according to an embodiment of this application;

[0027] Figure 10 This is a schematic diagram of the structure of form eight of the battery electrode according to an embodiment of this application.

[0028] The meanings of the reference numerals in the attached figures are as follows:

[0029] 1. Current collector; 2. Active coating; 21. First coating section; 211. First base coat; 212. First top coat; 22. Second coating section; 221. Second base coat; 222. Second top coat; 3. First groove; 4. Second groove. Detailed Implementation

[0030] To better understand and implement this application, the technical solutions in this application will be clearly and completely described below with reference to the accompanying drawings.

[0031] In the description of this application, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application 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. Therefore, they should not be construed as limitations on this application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0033] See Figures 1-10This application discloses a battery electrode sheet, which includes a current collector 1, an active coating 2, and a first groove 3. In some embodiments, the active coating 2 includes a first coating section 21 and a second coating section 22 arranged on the current collector 1, and the first coating section 21 can be located outside the coating of the second coating section 22 when the battery electrode sheet is wound; the first groove 3 is disposed on the first coating section 21. In this way, by winding the first coating section 21 around the outside of the second coating section 22, the stress on the first coating section 21 is less than that on the second coating section 22. Furthermore, the first groove 3 is provided on the first coating section 21, which allows for differentiated settings for different areas of the battery electrode sheet according to actual applications. This effectively prevents the first groove 3 from deforming and collapsing due to uneven stress, ensuring that the first groove 3 can improve the flow rate of the electrolyte, the wetting effect of the electrolyte on the battery electrode sheet, and the electrolyte storage capacity of the battery electrode sheet in actual applications. It also increases the contact reaction area of ​​the active coating 2 of the battery electrode sheet, alleviates the compression caused by the expansion of the battery electrode sheet, and thus improves the cycle and fast charging performance of the battery.

[0034] See Figure 1 , Figure 3 , Figure 4 , Figure 5 and Figure 6In some embodiments, with long-term use of the battery, the area where the second coating section 22 is located on the battery electrode may still face expansion and compression, causing electrolyte to accumulate on both sides of the second coating section 22, which affects the battery's cycle and fast-charging performance. Preferably, a second groove 4 extending along the mechanical stretching direction (Machine Direction, i.e., the MD direction) is also included, and the second groove 4 is disposed on the second coating section 22. In this way, by disposing the second groove 4 on the second coating section 22, which is subject to greater stress, and utilizing the characteristic of the second groove 4 extending along the MD direction, the second groove 4 can provide additional space to alleviate the expansion effect in the area where the second coating section 22 is located, preventing deformation and collapse of the second groove 4. This ensures that the second groove 4 can improve the electrolyte flow rate, the electrolyte wetting effect on the area where the second coating section 22 is located, and the electrolyte storage capacity of the area where the second coating section 22 is located, increasing the contact reaction area of ​​the active coating 2 in the area where the second coating section 22 is located, thereby improving the battery's cycle and fast-charging performance. In this embodiment, by placing the first groove 3 on the first coating section 21 and the second groove 4 on the second coating section 22, the first groove 3 and the second groove 4 are positioned at different locations, allowing the first groove 3 and the second groove 4 to be adapted to different stress conditions in different areas. This avoids deformation and collapse of the groove structure. In this way, the battery electrode can utilize the corresponding groove structure in different areas to improve the flow rate of the electrolyte, the wetting effect of the electrolyte on the battery electrode, and the electrolyte storage capacity of the battery electrode, increase the contact reaction area of ​​the active coating 2, and alleviate the compression caused by the expansion of the area, thereby improving the cycle and fast charging performance of the battery.

[0035] See Figure 2 In some embodiments, the current collector 1 has two oppositely arranged sides, and the second coating segment 22 includes a second base coating 221 and a second top coating 222, wherein: the second base coating 221 is disposed on at least one of the sides, the second top coating 222 is stacked on the second base coating 221, and the second groove 4 is disposed on the second top coating 222. Thus, the second base coating 221 and the second top coating 222 are stacked on at least one of the sides of the current collector 1, so that the second groove 4 is disposed on at least one side of the current collector 1. Optionally, when the second base coating 221 and the second top coating 222 are stacked on either side of the current collector 1, a corresponding active material is coated on the other side; optionally, when the second base coating 221 and the second top coating 222 are stacked on both sides of the current collector 1, then the second groove 4 is disposed on both sides of the current collector 1.

[0036] Optionally, the number of the second groove 4 can be one or more; optionally, when the number of the second groove 4 is multiple, the dimensions (length, width, and depth) of the second groove 4 can be different from each other; optionally, the second groove 4 is formed by laser burning the second surface coating 222. Specifically, in the three stages of electrode coating, cold pressing, or before winding, the active material on the second surface coating 222 is burned by laser to form the second groove 4 on the second surface coating 222. At the same time, the active material after burning can be adsorbed and removed by a dust collector, without the need for an additional process of cleaning the battery electrode.

[0037] Furthermore, after the second groove 4 is provided on the second surface coating 222, the active material on the current collector 1 will inevitably be lost. When the active material on the current collector 1 is lost too much, it will have a significant impact on the rated capacity or charging NP ratio of the battery, leading to poor phenomena such as low capacity or lithium plating, which seriously affects the cycle performance and storage performance of the battery. Preferably, the areal density of the second base coating layer 221 is greater than that of the second top coating layer 222, the compaction density of the second base coating layer 221 is greater than that of the second top coating layer 222, and the thickness of the second base coating layer 221 is greater than that of the second top coating layer 222. This effectively reduces the loss of active material caused by setting the second groove 4 on the second top coating layer 222, effectively reducing the impact of setting the second groove 4 on the cycle performance and storage performance of the battery. At the same time, the battery capacity is positively correlated with the compaction density, that is, the greater the compaction density, the greater the battery capacity. Therefore, by making the compaction density of the second base coating layer 221 greater than that of the second top coating layer 222, the large change in the compaction density of the active material on the current collector 1 after setting the second groove 4 on the second top coating layer 222 is prevented, effectively ensuring the battery capacity.

[0038] In some embodiments, since the area where the second coating section 22 is located needs to withstand greater stress, the second groove 4 may not be provided on the second coating section 22. (See reference...) Figure 2 , Figure 7 , Figure 8 , Figure 9 and Figure 10To prevent the collapse of the groove structure inside the battery electrode, but with long-term use of the battery, the area where the second coating section 22 is located may still face expansion and compression, causing the electrolyte to accumulate on both sides of the electrode, which may affect the battery's cycle and fast charging performance. Therefore, the size of the second groove 4 on the second coating section 22 needs to be set to a specific size, and the extension direction of the second groove 4 can only be the MD direction, to avoid uneven stress during use due to the large size and depth of the second groove 4, thereby preventing the collapse of the groove structure inside the battery electrode; preferably, the setting ratio of the second groove 4 on any side of the current collector 1 is R1, and the expression of R1 is: See also Figure 1 a1 is the length of the second groove 4, b1 is the width of the second groove 4, d1 is the depth of the second groove 4, n1 is the number of the second grooves 4 on any side of the current collector 1, M is the weight of the active coating 2 on any side of the current collector 1, X is the length of the second coating section 22, and S is the length of the current collector 1.

[0039] Specifically, the length a1 of the second groove 4 is less than or equal to the length X of the second coating section 22. The MD direction is parallel to the length direction of the second coating section 22. Therefore, the length a1 of the second groove 4 extending along the MD direction is less than or equal to the length X of the second coating section 22. This also means that the second groove 4 can penetrate the second coating section 22 but cannot touch the electrode tab. If the electrode tab is damaged, tape breakage is likely to occur during subsequent winding. Optionally, limited by existing processing technology, the length a1 of the second groove 4 is ≥ 0.005mm, that is, the current minimum value of the length a1 of the second groove 4 is 0.005mm. However, with the development of processing technology and corresponding processing equipment, the minimum value a1 of the length of the second groove 4 will increase. 1min It can be further reduced to 0.005 > a 1min The range is ≥0, therefore the current range of the length a1 of the second groove 4 is: X≥a1≥0.005mm. Optionally, to avoid uneven stress during use due to the excessive size of the second groove 4, the width b1 of the second groove 4 needs to be in the range: b1≤0.2mm, to prevent the second groove 4 from collapsing. Optionally, limited by the existing processing technology, the width b1 of the second groove 4 is ≥0.005mm, that is, the current minimum value of the width b1 of the second groove 4 is 0.005mm. However, with the development of processing technology and corresponding processing equipment, the minimum value b1 of the width of the second groove 4 will increase. 1min It can be further reduced to 0.005>b 1minThe range is ≥0, therefore the current range of the width b1 of the second groove 4 is: 0.2mm ≥ b1 ≥ 0.005mm. Optionally, the weight M of the active coating 2 on any side of the current collector 1 is the sum of the weights of the active materials of the first coating section 21 and the second coating section 22 located on any side of the current collector 1.

[0040] In some embodiments, since the area where the second coating section 22 is located needs to withstand greater stress, the second groove 4 may not be provided on the second coating section 22. Therefore, the minimum value of the setting ratio R1 of the second groove 4 on any side of the current collector 1 is 0, that is, 0≤R1. Furthermore, when the number of the second groove 4 exceeds a preset range, it will cause the setting ratio R1 of the second groove 4 on any side of the current collector 1 to increase, making the second groove 4 on any side of the current collector 1 prone to uneven stress during use. Therefore, R1≤10% to prevent... Since the number of the second grooves 4 exceeds the preset range, the setting ratio R1 of the second grooves 4 on any side of the current collector 1 is in the range of 0≤R1≤10%. This avoids deformation and collapse of the second grooves 4, ensures that the second grooves 4 can improve the flow rate of the electrolyte, the wetting effect of the electrolyte on the area where the second coating section 22 is located, and the liquid storage capacity of the area where the second coating section 22 is located, increase the contact reaction area of ​​the active coating 2 in the area where the second coating section 22 is located, alleviate the squeezing caused by the expansion of the area where the second coating section 22 is located, and thus improve the cycle and fast charging performance of the battery.

[0041] See Figure 2 In some embodiments, the first coating segment 21 includes a first base coating 211 and a first top coating 212. The first base coating 211 is disposed on at least one of the side surfaces, and the first top coating 212 is stacked on the first base coating 211. The first groove 3 is disposed on the first top coating 212. Thus, the first base coating 211 and the first top coating 212 are stacked on at least one side surface of the current collector 1, such that the first groove 3 is disposed on at least one side surface of the current collector 1. Preferably, the stacked structure formed by the first base coating 211 and the first top coating 212 and the stacked structure formed by the second base coating 221 and the second top coating 222 are sequentially arranged on the current collector 1; optionally, when the first base coating 211 and the first top coating 212 are stacked on any side of the current collector 1, the other side is coated with a corresponding active material; optionally, when the first base coating 211 and the first top coating 212 are stacked on both sides of the current collector 1, the first groove 3 is provided on both sides of the current collector 1.

[0042] Optionally, the number of the first grooves 3 can be one or more. Optionally, when the number of the first grooves 3 is multiple, the size and extension direction of the first grooves 3 can be different. Optionally, the first grooves 3 are formed by laser burning the first surface coating 212. Specifically, in the three stages of electrode coating, cold pressing, or before winding, the active material on the first surface coating 212 is burned by laser to form the first grooves 3 on the first surface coating 212. At the same time, the active material after burning can be adsorbed and removed by a dust collector, without the need for additional cleaning of the battery electrode.

[0043] Optionally, the first groove 3 may extend along the TD direction (Transverse Direction, i.e., the transverse direction, which is perpendicular to the MD direction) or the MD direction; optionally, the cross-sectional shape of the first groove 3 is not unique, and the cross-sectional shape of the first groove 3 may be one of the following: rectangular, trapezoidal, conical, and arc-shaped; optionally, the first groove 3 is uniformly distributed on the first surface coating 212; optionally, the first groove 3 is distributed in a local area of ​​the first surface coating 212; optionally, the first groove 3 on the same first surface coating 212 is spaced apart, that is, adjacent first groove 3 are independent and separated from each other, or the first groove 3 is intersected; furthermore, the first surface coating 212 has both intersected and spaced first groove 3, that is, the distribution of the first groove 3 is one or more of intersecting and spaced distribution.

[0044] Optionally, the form of the battery electrode is described in one reference. Figure 3 As shown, the second surface coating 222 is provided with a second groove 4 extending along the MD direction, and the first surface coating 212 is provided with a first groove 3 extending along the TD direction. The first groove 3 and the second groove 4 are used to increase the storage capacity of the battery electrode for electrolyte and increase the reaction area of ​​the active material on the surface of the battery electrode, thereby improving the reaction activity.

[0045] Optionally, the second type of battery electrode can be referred to. Figure 4 As shown, the second surface coating 222 is provided with a second groove 4 extending along the MD direction, and the first groove 3 on the first surface coating 212 is inclined in the TD direction, thereby greatly increasing the reaction area of ​​the active material on the surface of the battery electrode and the storage capacity of the electrolyte. In addition, the first groove 3 can serve as a gas exhaust channel, effectively reducing the internal pressure of the battery, improving the safety performance of the battery, and mitigating the occurrence of side reactions between the battery electrodes.

[0046] Optionally, the battery electrode may be in the form of three references. Figure 5 As shown, the second surface coating 222 is provided with a second groove 4 extending along the MD direction, and the first surface coating 212 is provided with a first groove 3 extending along the MD direction. The first groove 3 and the second groove 4 are used to increase the reaction area of ​​the active material on the surface of the battery electrode, improve the reaction activity, and provide additional space to alleviate the expansion of the battery electrode, prevent the first groove 3 and / or the second groove 4 from collapsing and deforming, and improve the phenomenon of uneven current in the middle and both sides of the battery electrode.

[0047] Optionally, the form of the battery electrode is described in four references. Figure 6 As shown, the second surface coating 222 is provided with a second groove 4 extending along the MD direction, and the first surface coating 212 is provided with at least two first grooves 3. One of the first grooves 3 extends along the MD direction, and the other first groove 3 extends along the TD direction. The two first grooves 3 with different extension directions have an intersection point, thereby increasing the reaction area of ​​the active material, improving the reaction activity and electrolyte storage capacity, and alleviating the expansion effect of the battery electrode, preventing the first groove 3 and / or the second groove 4 from collapsing and deforming, and improving the phenomenon of uneven current in the middle and both sides of the battery electrode.

[0048] Optionally, the form of the battery electrode is described in reference five. Figure 7 As shown, the second surface coating 222 does not have the second groove 4, while the first surface coating 212 is provided with the first groove 3 extending along the TD direction. The first groove 3 is used to increase the storage capacity of the battery electrode for electrolyte and increase the reaction area of ​​the active material on the surface of the battery electrode, thereby improving the reaction activity.

[0049] Optionally, the battery electrode may be in the form of six (see reference six). Figure 8 As shown, the second surface coating 222 does not have the second groove 4, and the first groove 3 on the first surface coating 212 is inclined in the TD direction, thereby greatly increasing the reaction area of ​​the active material on the surface of the battery electrode and the storage capacity of the electrolyte. In addition, the first groove 3 can serve as a gas exhaust channel, effectively reducing the internal pressure of the battery, improving the safety performance of the battery, and mitigating the occurrence of side reactions between the battery electrodes.

[0050] Optionally, the form of the battery electrode can be referred to in section seven. Figure 9As shown, the second surface coating 222 does not have the second groove 4, and the first surface coating 212 is provided with the first groove 3 extending along the MD direction, so that the first groove 3 increases the reaction area of ​​the active material on the surface of the battery electrode, improves the reaction activity, and can provide additional space to alleviate the electrode expansion effect, prevent the first groove 3 from collapsing and deforming, and improve the phenomenon of uneven current in the middle and both sides of the battery electrode.

[0051] Optionally, the form of the battery electrode is described in reference eight. Figure 10 As shown, the second surface coating 222 has no second groove 4, and the first surface coating 212 is provided with at least two first grooves 3. One of the first grooves 3 extends along the MD direction, and the other first groove 3 extends along the TD direction. The two first grooves 3 with different extension directions have an intersection point, thereby increasing the reaction area of ​​the active material, improving the reaction activity and electrolyte storage capacity, and alleviating the expansion effect of the battery electrode, preventing the first groove 3 from collapsing and deforming, and improving the phenomenon of uneven current in the middle and both sides of the battery electrode.

[0052] Furthermore, after the first groove 3 is set on the first surface coating 212, the active material on the current collector 1 will inevitably be lost. When the active material on the current collector 1 is lost too much, it will have a significant impact on the rated capacity or charging NP ratio of the battery, leading to poor phenomena such as low capacity or lithium plating, which seriously affects the cycle performance and storage performance of the battery. Preferably, the areal density of the first base coating layer 211 is greater than that of the first top coating layer 212, the compaction density of the first base coating layer 211 is greater than that of the first top coating layer 212, and the thickness of the first base coating layer 211 is greater than that of the first top coating layer 212. This effectively reduces the loss of active material caused by setting the first groove 3 on the first top coating layer 212, effectively reducing the impact of setting the first groove 3 on the cycle performance and storage performance of the battery. At the same time, the battery capacity is positively correlated with the compaction density, that is, the greater the compaction density, the greater the battery capacity. Therefore, by making the compaction density of the first base coating layer 211 greater than that of the first top coating layer 212, the compaction density of the active material on the current collector 1 is prevented from changing significantly after setting the first groove 3 on the first top coating layer 212, effectively ensuring the battery capacity.

[0053] In some embodiments, the first groove 3 on any side of the current collector 1 is set in a ratio of R2, where R2 is expressed as: See also Figure 1a2 is the length of the first groove 3, b2 is the width of the first groove 3, d2 is the depth of the first groove 3, and n2 is the number of the first grooves 3 on any side of the current collector 1. Optionally, the length direction of the first coating section 21 is parallel to the MD direction, so the length of the first coating section 21 is (SX), wherein the length X of the second coating section 22 can be set by the user according to the actual situation; Optionally, the length a2 of the first groove 3 is less than or equal to the length (SX) of the first coating section 21, which also means that the first groove 3 can penetrate the first coating section 21, but cannot touch the electrode tab. If the electrode tab is damaged, the tape is prone to breakage in subsequent winding. Optionally, due to the limitations of the existing processing technology, the length a2 of the first groove 3 is ≥ 0.005mm, that is, the current minimum value of the length a2 of the first groove 3 is 0.005mm. However, with the development of processing technology and corresponding processing equipment, the minimum value a2 of the length of the first groove 3 is... 2min It can be further reduced to 0.005 > a 2min The range is ≥0, therefore the current range of the length a2 of the first groove 3 is: (SX)≥a1≥0.005mm. Similarly, the width b2 of the first groove 3 is less than or equal to the width L of the first coating section 21, and is limited by the existing processing technology, the width b2 of the first groove 3 is ≥0.005mm. However, with the development of processing technology and corresponding processing equipment, the minimum value b of the width of the first groove 3 will be... 2min It can be further reduced to 0.005 > b 2min The range is ≥0, so the current range of the width b2 of the first groove 3 is: L≥b1≥0.005mm.

[0054] Furthermore, based on existing processes, setting the first groove 3 on the first surface coating 212 inevitably leads to the loss of active material on the current collector 1. Excessive loss of active material on the current collector 1 significantly impacts the battery's rated capacity or charging NP ratio, resulting in low capacity or lithium plating, severely affecting the battery's cycle performance and storage performance. Preferably, 0.01% ≤ R2 ≤ 20% is preferred to avoid excessive loss of active material on the current collector 1 after setting the first groove 3 on the first surface coating 212. Simultaneously, the groove 3 ensures that the electrolyte flow rate, the electrolyte wetting effect on the area where the first coating section 21 is located, and the electrolyte storage capacity of the area where the first coating section 21 is located are all improved. This increases the contact reaction area of ​​the active coating 2 in the area where the first coating section 21 is located, alleviates the compression caused by the expansion of the area where the first coating section 21 is located, and thus improves the battery's cycle and fast-charging performance.

[0055] In some embodiments, a battery core includes: a separator and two battery electrodes as described above, wherein the active coating 2 in one of the battery electrodes is composed of a first active material, and the active coating 2 in the other battery electrode is composed of a second active material; the separator is disposed between the two battery electrodes to separate the two battery electrodes. Optionally, the first active material is a positive electrode active material, wherein the positive electrode active material is any one or more of lithium iron phosphate, ternary materials such as nickel cobalt manganese, lithium manganese oxide, lithium cobalt oxide, and lithium nickel cobalt aluminum oxide; the second active material is an negative electrode active material, wherein the negative electrode active material is any one or more of artificial graphite, natural graphite, hard carbon, soft carbon, and silicon; thus, the battery electrode with the first active material is a positive electrode, and the battery electrode with the second active material is a negative electrode. Optionally, the two battery electrodes are stacked with the separator, and the separator is placed between the two battery electrodes to separate the two battery electrodes, and then the structure formed by stacking the two battery electrodes with the separator is wound to form a battery core.

[0056] In some embodiments, the structure formed by stacking two battery electrodes and the separator is wound to form a battery core, driving the first coating section 21 to be wound around the outside of the second coating section 22, so that the stress borne by the area where the first coating section 21 is located is less than the stress borne by the area where the second coating section 22 is located. Preferably, the length of the second coating section 22 is expressed as: Where x is the thickness of any of the battery electrodes, y is the thickness of the other battery electrode, z is the thickness of the separator, r is the diameter of the winding needle, and m is the number of turns of the second coating section 22. Optionally, since the winding needle includes an inner needle and an outer needle, the inner needle clamps the starting end of the second coating section 22, while the outer needle opens to provide space for the forming of the battery electrode and the separator. Optionally, during the winding forming of the battery electrode, the inner needle clamps the starting end of the second coating section 22 and rotates it, driving the second coating section 22 to wind at least one inner turn. Since the starting end of the first coating section 21 is connected to the end of the second coating section 22, the inner needle can pull the first coating section 21 to wind around the outer periphery of the inner turn through the second coating section 22. Therefore, when calculating the length X of the second coating section 22, the influence of the winding needle diameter r needs to be considered. Optionally, the number of turns of the second coating section 22 can be determined according to factors such as battery specifications, capacity requirements, performance stability, manufacturing process, and equipment. Preferably, the number of turns of the second coating section 22 is in the range of 1≤m≤50. This effectively limits the length of the second coating section 22 within the battery core, enabling differentiated settings for different areas of the battery core based on actual applications. This effectively avoids deformation and collapse of the groove structure, thereby driving the battery core to utilize the first groove 3 or the second groove 4 in different areas to improve the flow rate of the electrolyte, the wetting effect of the electrolyte on the battery core, and the liquid storage capacity of the battery electrode sheets. This increases the contact reaction area of ​​the active coating 2, alleviates the squeezing caused by the expansion of the battery core, and thus improves the cycle and fast charging performance of the battery.

[0057] The technical means disclosed in this application are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. A battery electrode, characterized in that, include: current collector(1); An active coating (2) is provided, comprising a first coating section (21) and a second coating section (22) arranged on the current collector (1), wherein the first coating section (21) is located outside the second coating section (22) when the battery electrode is wound. The first groove (3) is disposed on the first coating section (21).

2. The battery electrode according to claim 1, characterized in that: It also includes a second groove (4) extending along the mechanical stretching direction, the second groove (4) being disposed on the second coating section (22).

3. The battery electrode according to claim 2, characterized in that: The current collector (1) has two oppositely arranged sides, and the second coating section (22) includes a second base coating (221) and a second top coating (222), wherein: The second base coating (221) is disposed on at least one of the side surfaces, the second top coating (222) is stacked on the second base coating (221), and the second groove (4) is disposed on the second top coating (222).

4. The battery electrode according to claim 3, characterized in that: The first coating section (21) includes a first base coating (211) and a first top coating (212). The first base coating (211) is disposed on at least one of the sides, the first top coating (212) is stacked on the first base coating (211), and the first groove (3) is disposed on the first top coating (212).

5. The battery electrode according to any one of claims 2-4, characterized in that: The second groove (4) on any side of the current collector (1) is set in a ratio of R1; The expression for R1 is: Where a1 is the length of the second groove (4), b1 is the width of the second groove (4), d1 is the depth of the second groove (4), n1 is the number of the second grooves (4) on any side of the current collector (1), M is the weight of the active coating (2) on any side of the current collector (1), X is the length of the second coating segment (22), and S is the length of the current collector (1).

6. The battery electrode according to claim 5, characterized in that: 0≤R1≤10％。 7. The battery electrode according to any one of claims 1-4, characterized in that: The first groove (3) on any side of the current collector (1) is set in an R2 ratio; The expression for R2 is: Where a2 is the length of the first groove (3), b2 is the width of the first groove (3), d2 is the depth of the first groove (3), and n2 is the number of the first grooves (3) on any side of the current collector (1).

8. A battery core, characterized in that, include: The separator and two battery electrodes as described in any one of claims 1-7, Wherein, the active coating (2) in any one of the battery electrodes is composed of a first active material, and the active coating (2) in the other battery electrode is composed of a second active material; The separator is disposed between the two battery electrodes to separate the two battery electrodes.

9. The battery core according to claim 8, characterized in that: The expression for the length of the second coating segment (22) is: Where x is the thickness of any of the battery electrodes, y is the thickness of the other battery electrode, z is the thickness of the separator, r is the diameter of the winding needle, and m is the number of turns of the second coating section (22).

10. The battery core according to claim 9, characterized in that: 1≤m≤50。

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