Improved shaped-coating positive electrode sheet, lithium ion battery and electronic device

Abstract

The application provides an improved shaped-coating positive electrode sheet, a lithium ion battery and an electronic device. The positive electrode sheet comprises a current collector and at least one active material layer on the current collector. The positive electrode sheet is divided into a main area and an edge area in the length direction. The thickness of the active material layer in the part of the edge area is smaller than that in the part of the main area. The edge area has a modification unit, and the modification unit comprises at least one modification structure. In the thickness direction, the modification structure protrudes in the direction away from the extension plane of the part of the main area of the current collector. Based on the arrangement of the modification unit, the thickness difference between the edge area and the main area can be reduced, which helps to ensure the adhesion consistency between different areas of the electrode sheet and the separator, reduces the risk of lithium precipitation, and increases the cycle life. The cycle life, energy density and safety performance of the lithium ion battery are improved. The reliability and working performance of the electronic device are improved.

Description

Technical Field

[0001] This application belongs to the field of lithium-ion battery technology and relates to an improved irregularly shaped coated positive electrode, a lithium-ion battery, and an electronic device. Background Technology

[0002] Lithium-ion batteries are a core product of the energy era, with enormous potential for future market growth. Currently, lithium-ion battery research is no longer limited to long cycle life and high energy density; it also requires fast charging capabilities and high power output. For higher power charging and discharging, in addition to focusing on material selection and process design, optimizing battery structure design is paramount.

[0003] In terms of electrode design, conventional lithium-ion batteries typically have only one tab for both the positive and negative electrodes, located at one end of the electrode sheet. The electrode sheets are then assembled using a winding method to form the battery cell. Alternatively, for electrodes with centrally located tabs, the tabs are situated in the middle of the electrode sheet. These are generally processed using methods such as laser cleaning, spacer coating, and adhesive bonding. Lithium-ion batteries with centrally located tabs have lower internal resistance and better rate performance. However, lithium-ion batteries with these conventional tab designs struggle to meet the power supply demands of high-power devices, such as drones, robotic vacuum cleaners, and robots. Multi-tab designs have emerged to address this need. Multi-tab designs involve arranging multiple tabs on the electrode sheet. This design allows for a more uniform current distribution during charging and discharging, resulting in lower internal resistance and less polarization, thereby improving the battery's charge / discharge rate performance. Simultaneously, more uniform current transmission and heat generation improve the battery's heat dissipation performance. Multi-tab designs typically use foil as internal tabs, which necessitates a different electrode coating method than usual. Currently, the mainstream methods include continuous zebra coating, intermittent zebra-pattern coating, and other irregularly shaped coating methods resulting from special battery structures. However, in practical applications, it has been found that lithium-ion batteries with irregularly shaped coated electrodes have some performance deficiencies (e.g., cycle life) that require further improvement.

[0004] Therefore, how to provide an improved irregularly shaped coated positive electrode, lithium-ion battery, and electronic device to improve the performance of lithium-ion batteries has become an important technical problem that needs to be solved by those skilled in the art.

[0005] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this application is to provide an improved irregularly shaped coated positive electrode, a lithium-ion battery and an electronic device, to solve the problem that the performance of lithium-ion batteries with irregularly shaped coated electrodes in the prior art needs to be improved.

[0007] To achieve the above and other related objectives, in a first aspect, this application provides an improved irregularly shaped coated positive electrode sheet, comprising a current collector and at least one active material layer, wherein the active material layer is located on the current collector, and the improved irregularly shaped coated positive electrode sheet is divided into a main region and an edge region along its length; wherein,

[0008] The thickness of the active material layer in the edge region is less than the thickness of the active material layer in the main body region.

[0009] The edge region has a decorative unit, and the decorative unit includes at least one decorative structure that protrudes in the thickness direction along a direction away from the extension plane of the portion of the current collector located in the main region.

[0010] In an optional embodiment, the modification structure includes at least one of a deformation modification structure and a compensation modification structure; wherein, the deformation modification structure is formed by local deformation of the current collector and the active material layer, and the compensation modification structure is formed by active material units located on the side of the active material layer away from the current collector.

[0011] In an optional embodiment, the improved irregularly shaped coated positive electrode includes a first active material layer and a second active material layer, wherein the first active material layer and the second active material layer are located on opposite sides of the current collector in the thickness direction.

[0012] In an optional embodiment, the compensating modification structure is provided on both the first active material layer and the second active material layer; wherein, the compensating modification structure on the first active material layer and the compensating modification structure on the second active material layer are aligned; or, the compensating modification structure on the first active material layer and the compensating modification structure on the second active material layer are staggered.

[0013] Alternatively, one of the first active material layer and the second active material may have the compensation modification structure, and the edge region may also have the deformation modification structure;

[0014] Alternatively, the edge region may have only the deformable modification structure, all of which protrude in the same direction, or at least two of which protrude in different directions.

[0015] In an optional embodiment, the percentage between the height of the modified structure and the thickness of the portion of the improved irregularly shaped coated cathode located in the main region ranges from 1% to 30%; and / or,

[0016] The ratio between the height and width of the decorative structure is in the range of 0.0007 to 0.03.

[0017] In an optional embodiment, the edge region includes a plurality of the decorative structures; wherein,

[0018] The multiple modified structures are arranged in an array, or the multiple modified structures are irregularly distributed; and / or,

[0019] The multiple decorative structures have the same size, or the sizes of the multiple decorative structures increase in a direction away from the main body region; wherein the size includes at least one of width, height and length.

[0020] In an optional embodiment, the length of the edge region is less than or equal to 20 mm; and / or,

[0021] The thickness of the portion of the improved irregularly shaped coated positive electrode sheet located in the main body region ranges from 40 μm to 200 μm; and / or,

[0022] The height of the modified structure is less than or equal to 100 μm; and / or,

[0023] The width of the modified structure ranges from 0.1 mm to 5 mm; and / or,

[0024] The spacing between any two adjacent modified structures ranges from 0.1 mm to 7 mm.

[0025] In an optional embodiment, the edge region further includes a second modification unit, the second modification unit comprising at least one second modification structure located in the active material layer, and in the thickness direction, the second modification structure is recessed along the extension direction of the portion of the current collector located in the main region.

[0026] In an optional embodiment, the improved irregularly shaped coated positive electrode sheet includes at least one of zebra-coated positive electrode sheet, grid-patterned zebra intermittently coated positive electrode sheet, and square-shaped coated positive electrode sheet; and / or,

[0027] The orthographic projection of the modified structure onto the extended plane is at least one of the following: straight line, wavy line, broken line, curved line, circle, polygon, heart shape, teardrop shape, fan shape, and irregular shape.

[0028] Thirdly, this application provides an electronic device comprising a lithium-ion battery as described in the second aspect.

[0029] As described above, the improved irregularly shaped coated positive electrode of this application reduces the thickness difference between the active material layer in the edge region and the active material layer in the main body region by arranging modification units in the thinner edge region and modifying the edge region based on the modification units. This reduction in thickness difference achieves the following beneficial effects: it helps increase the contact area between the internal electrode and the separator during the pressing process, ensuring consistent adhesion between different areas of the electrode and the separator, avoiding gaps between the edge region and the separator, reducing the risk of lithium plating in the edge region, and increasing the cycle life of the cell; based on the thickness modification of the edge region, the stress on each region of the cell is more uniform during the pressing process, resulting in a more uniform overall thickness distribution of the cell. In mass production, the average thickness of the cell can be reduced by approximately 20 μm. Through structural modification of the edge region, the active material in the edge region can be fully utilized, helping to reduce the internal resistance of the cell, improve current transmission consistency, and increase the energy density of the battery. Furthermore, by designing the arrangement, size, spacing, and other parameters of the modification structure in the modification unit, the heat distribution and diffusion rate inside the cell can be controlled more evenly, reducing the safety risks of the battery under abnormal conditions such as overcharging, over-discharging, and short circuits. Attached Figure Description

[0030] Figure 1 The diagram shown is a partial structural schematic of the improved irregularly shaped coated positive electrode sheet provided in the embodiments of this application.

[0031] Figure 2 The diagram shown is a first side view of the improved irregularly shaped coated positive electrode sheet provided in the embodiments of this application.

[0032] Figure 3 The diagram shown is a second side view of the improved irregularly shaped coated positive electrode sheet provided in the embodiments of this application.

[0033] Figure 4 The diagram shown is a third side view of the improved irregularly shaped coated positive electrode sheet provided in the embodiments of this application.

[0034] Figure 5 The diagram shown is a fourth side view of the improved irregularly shaped coated positive electrode sheet provided in the embodiments of this application.

[0035] Figure 6 The diagram shown is a fifth side view of the improved irregularly shaped coated positive electrode provided in the embodiments of this application.

[0036] Figure 7The diagram shows a comparison of the thickness distribution of lithium-ion batteries in half-charge state between Examples 1-12 and Comparative Examples 1-2 of this application.

[0037] Explanation of reference numerals in the attached figures:

[0038] 10-Irregularly shaped coated positive electrode sheet, 101-Current collector, 102-Active material layer, 102a-First active material layer, 102b-Second active material layer, A1-Main region, A2-Edge region, A3-Empty foil region, F-Extending plane;

[0039] 20-Modification structure, 20a-Deformation modification structure, 20b-Compensation modification structure;

[0040] 30 - Insulation layer. Detailed Implementation

[0041] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application.

[0042] Please see Figures 1 to 7 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of this application. Therefore, the drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0043] After analyzing the performance of lithium-ion batteries with irregularly shaped coated electrodes as mentioned in the background technology, it was found that the edges of the active material layer coated on the current collector in electrodes formed by irregular coating exhibit a certain degree of thinning. For irregularly coated negative electrodes, the powder in the thinned areas can be removed by laser cleaning. However, for irregularly coated positive electrodes, an insulating layer is also provided at the edges of the thinned areas, and the active material layer of the positive electrode is an oil-based system. The special characteristics of its structure and material system make laser cleaning unsuitable for removing the powder in the thinned areas. In multi-tab, laminated, or other irregularly shaped battery cells, the thinning regions between adjacent layers are usually located in corresponding positions, presenting an overall structure of cumulative thinning regions. This results in the area formed by the superposition of thinning regions in the battery cell being significantly thinner than other areas. This makes the thinner area less stressed during subsequent pressurization, and tiny gaps may exist between the electrode and the separator, thereby increasing the risk of lithium plating during charging in the thinner area, especially during long-cycle charging, which in turn affects the cycle life of the battery cell.

[0044] Based on the above analysis, this application provides an improved irregularly shaped coated positive electrode sheet. By arranging modification units in the edge region of the improved irregularly shaped coated positive electrode sheet, and the modification units including at least one modification structure, the risk of lithium plating caused by the thin edge region is reduced, thereby improving the cycle life of the lithium-ion battery.

[0045] This application provides an improved irregularly shaped coated positive electrode sheet (hereinafter referred to as "positive electrode sheet"). Please refer to [link to relevant documentation]. Figure 1 , Figure 1 A partial structural schematic diagram of the positive electrode is shown (which can be regarded as a top view or a bottom view of the structure). The positive electrode 10 includes a current collector 101 and at least one active material layer 102, wherein the active material layer 102 is located on one side of the current collector 101.

[0046] Specifically, the positive electrode 10 is divided into a main region A1 and an edge region A2 along its length. (See also...) Figure 2 This diagram shows a first side view of the positive electrode structure. The thickness of the active material layer 102 in the edge region A2 is less than the thickness of the active material layer 102 in the main region A1. The edge region A2 has a modification unit, and the modification unit includes at least one modification structure 20. In the thickness direction, the modification structure 20 protrudes along an extension plane F away from the portion of the current collector 101 located in the main region A1. The "extension plane F" can be defined as the central axis surface of the portion of the current collector 101 located in the main region A1 along its length. To avoid ambiguity, Figure 1 In the diagram, X represents the width direction of the positive electrode plate. Figures 1 to 6 In the diagram, Y represents the length direction of the positive electrode. Figures 2 to 6 In the diagram, Z represents the thickness direction of the positive electrode.

[0047] It should be noted that the side of the modification structure 20 away from the extension plane F is not higher than the side of the active material layer 102 located in the main region A1 away from the extension plane F. That is, the modification structure 20 is provided to compensate for the fact that the thickness of the edge region A2 is thinner than the thickness of the main region A1. It is sufficient to make the thickness of the part of the edge region A2 where the modification structure 20 is provided close to the thickness of the main region A1 (keep it flush or slightly lower than its thickness). Otherwise, it may have the opposite effect. For example, the arrangement of the modification structure 20 may introduce new gaps between the positive electrode 10 and the separator, affecting the contact area and adhesion effect.

[0048] Next, please combine Figures 2 to 6 The specific structure and distribution of the modification units in the positive electrode 10 provided in this application embodiment are illustrated by way of example. Figures 3 to 6 The second to fifth side view structural diagrams of the positive electrode are shown respectively.

[0049] In some embodiments, such as Figure 3 and Figure 6 As shown, the percentage (H / T×100%) between the height H of the modified structure 20 and the thickness T of the portion of the positive electrode 10 located in the main body region A1 ranges from 1% to 30% (inclusive). For example, the percentage of H to T can be 5%, 10%, 15%, 20%, or 25%. To avoid ambiguity, the height H of the modified structure 20 refers to the distance between the side of the modified structure 20 away from the current collector 101 and the extending plane F minus half the thickness of the current collector 101 and the thickness of the active material layer 102 directly below the modified structure 20. The thickness T of the portion of the positive electrode 10 located in the main body region A1 refers to the sum of the thickness of the current collector 101 and the thickness of the active material layer 102 in the main body region A1. Wherein, when the positive electrode 10 includes two active material layers 102, T is the sum of the thickness of the two active material layers 102 and the thickness of the current collector 101.

[0050] In some embodiments, such as Figure 3 and Figure 6As shown, the ratio between the height H and the width W of the modified structure 20 ranges from 0.0007 to 0.03 (inclusive). For example, H / W can be 0.001, 0.005, 0.01, 0.015, 0.02, or 0.025. To avoid ambiguity, the length of the modified structure 20 refers to its dimension along the width direction of the positive electrode 10. Regarding the width of the modified structure 20, there are two cases (understood in conjunction with the following text): When the modified structure 20 is a compensating modified structure, the width of the modified structure 20 refers to its dimension along the length direction of the positive electrode 10; and when the modified structure 20 is a compensating modified structure, the width of the modified structure 20 is the product of its dimension along the length direction of the modified structure and the cosine of the angle between the contact surface between the modified structure and the active material layer 102 and the extending plane. Furthermore, when the orthographic projection of the decorative structure 20 onto the extending plane F is circular, the diameter of its orthographic projection is equal to the width of the decorative structure 20.

[0051] In some embodiments, such as Figure 3 and Figure 6 As shown, the length L of the edge region A2 is less than or equal to 20 mm. For example, L can be 5 mm, 10 mm, or 15 mm. The thickness T of the portion of the positive electrode 10 located in the main region A1 ranges from 40 μm to 200 μm (inclusive of endpoints). For example, T can be 80 μm, 120 μm, or 160 μm. The height H of the modification structure 20 is less than or equal to 100 μm. For example, H can be 20 μm, 40 μm, 60 μm, or 80 μm. The width W of the modification structure 20 ranges from 0.1 mm to 5 mm (inclusive of endpoints). For example, W can be 0.8 mm, 1.6 mm, 2.4 mm, 3.2 mm, 4.0 mm, or 4.5 mm. The specific length of the edge region A2 is set based on the coating equipment and battery design requirements.

[0052] In some embodiments, the modification structure 20 includes at least one of a deformation modification structure 20a and a compensation modification structure 20b; wherein the deformation modification structure 20a is formed by partial deformation of the current collector 101 and the active material layer 102, and the compensation modification structure 20b is formed by active material units located on the side of the active material layer 102 away from the current collector 101, wherein the active material unit refers to a protruding structure made of a material substantially the same as the active material layer 102. For example, such as Figure 2 and Figure 6 As shown, the modified structure 20 is a deformation-type modified structure 20a, or for example, as... Figure 3 and Figure 4 As shown, the modification structure 20 is a compensating modification structure 20b. More specifically, the compensating modification structure 20b can be considered as adding some active material to the side of the active material layer 102 away from the current collector 101 to form an active material unit, and compensating for the local thickness of the active material layer 102 in the edge region A2 based on the arrangement of the active material units. The deformation modification structure 20a, on the basis of the already formed active material layer 102, applies pressure to the active material layer 102 and the current collector 101 in the edge region A2 to cause local deformation of the active material layer 102 and the current collector 101, so that the side of the active material layer 102 in the edge region A2 away from the current collector 101 is nearly flush with the side of the active material layer 102 in the main region A1 away from the current collector 101, rather than additionally increasing the local thickness of the active material layer 102 in the edge region A2.

[0053] In some embodiments, the deformable modification structure 20a includes an embossed deformable modification structure 20a (formed based on an embossing process), and the compensating modification structure 20b includes a dot-coating compensating modification structure 20b (formed based on a dot-coating process), a spray-coating compensating modification structure 20b (formed based on a spray-coating process), a printing compensating modification structure 20b (formed based on a printing process), or a 3D printing compensating modification structure 20b (formed based on a 3D printing process). In practical applications, the appropriate type of modification structure 20 can be arranged according to actual needs.

[0054] In some embodiments, such as Figures 2 to 6 As shown, the positive electrode 10 includes a first active material layer 102a and a second active material layer 102b, which are located on opposite sides of the current collector 101 in the thickness direction. It should be noted that although the accompanying drawings do not show a side view of the positive electrode 10 with only a single active material layer 102, this does not mean that the solution in this application is unsuitable for edge region structure modification of the positive electrode 10 with a single active material layer 102.

[0055] The edge region A2 has only the deformable modification structure 20a, and the protrusion direction of the deformable modification structure 20a in the edge region A2 can include the following two cases:

[0056] In some embodiments, such as Figure 6 As shown, all the deformable modification structures 20a protrude in the same direction (which can be considered as recessed in opposite directions). For example, from the perspective of the first active material layer 102a to the second active material layer 102b (e.g., from top view), Figure 6All the aforementioned deformable modification structures 20a protrude from the first active material layer 102a in a direction away from the second active material layer 102b, and from the perspective of the second active material layer 102b to the first active material layer 102a (e.g., looking down), Figure 6 All the deformable modification structures 20a described herein are recessed from the second active material layer 102b in a direction away from the first active material layer 102b. Alternatively, all the deformable modification structures 20a may be recessed in a direction away from the first active material layer 102b. Figure 6 The protrusions (or depressions) of the deformable modification structure 20a shown are protruding (or recessed) in opposite directions.

[0057] In other embodiments, at least two of the deformable modification structures 20a protrude in different directions, for example, as Figure 2 As shown, a portion of the modification structure 20 protrudes from the extension plane F along a side away from the first active material layer 102a (e.g., protruding from top to bottom), while another portion of the modification structure 20 protrudes from the extension plane F along a side away from the second active material layer 102b (e.g., protruding from bottom to top).

[0058] In some embodiments, such as Figure 3 and Figure 4 As shown, both the first active material layer 102a and the second active material layer 102b are provided with the compensating modification structure 20b. In this case, the arrangement of the compensating modification structures 20b on the first active material layer 102a and the second active material layer 102b includes the following two scenarios:

[0059] like Figure 3 As shown, the compensating modification structure 20b on the first active material layer 102a is aligned with the compensating modification structure 20b on the second active material layer 102b.

[0060] Or, such as Figure 4 As shown, the compensating modification structure 20b on the first active material layer 102a is staggered from the compensating modification structure 20b on the second active material layer 102b.

[0061] In other embodiments, such as Figure 5 As shown, one of the first active material layer 102a and the second active material is provided with the compensating modification structure 20b, and the edge region A2 also has the deformation modification structure 20a. Further, in this case, the compensating modification structure 20b and the deformation modification structure 20a can be arranged alternately.

[0062] In some embodiments, the edge region A2 includes a plurality of the decorative structures 20. The plurality of decorative structures 20 are arranged in an array (i.e., regularly), or irregularly. Further, the array distribution includes at least one of equal-spaced and unequal-spaced distributions. An equal-spaced distribution can be a plurality of decorative structures 20 arranged at equal intervals along the same width direction, and / or a plurality of decorative structures 20 arranged at equal intervals along the same length direction. An unequal-spaced distribution can be a plurality of decorative structures 20 arranged at unequal intervals along the same width direction, and / or a plurality of decorative structures arranged at partial intervals along the same length direction, etc. The distribution pattern of the plurality of decorative structures 20 can be set based on actual needs.

[0063] In some embodiments, when the edge region A2 includes a plurality of the decorative structures 20, the dimensions of the plurality of decorative structures 20 include the following two cases:

[0064] The multiple decorative structures 20 have the same size. Alternatively, the sizes of the multiple decorative structures 20 increase in a direction away from the main body region A1. The size includes at least one of width, height, and length. For example, the sizes of the multiple decorative structures 20 increase in a stepwise manner in a direction away from the main body region A1 to match the gradually decreasing thickness of the active material layer 102 in the edge region A2 in that direction.

[0065] In some embodiments, the spacing D between any two adjacent decorative structures 20 ranges from 0.1 mm to 7 mm (including endpoint values). For example, D can be 0.5 mm, 1.0 mm, 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm, or 6.0 mm.

[0066] In some embodiments, the orthographic projection of the modification structure 20 onto the extending plane F is at least one of the following: a straight line, a wavy line, a broken line, a curve, a circle, a polygon, a heart shape, a teardrop shape, a fan shape, and an irregular shape. Wherein, when the orthographic projection of the modification structure 20 onto the extending plane F is a straight line, the extending direction of the modification structure 20 is orthogonal, parallel, or oblique to the length direction of the positive electrode 10; correspondingly, the length of the modification structure 20 can be less than, equal to, or greater than the width of the positive electrode 10. Furthermore, a plurality of the modification structures 20 may also constitute the modification unit having a mesh-like structure.

[0067] In some embodiments, the positive electrode 10 further includes an empty foil region A3, which is located on the side of the edge region A2 away from the main body region A1. The length of the current collector 101 is greater than the length of the active material layer 102, and the portion of the current collector 101 located in the empty foil region A3 is not coated with the active material layer 102.

[0068] In some embodiments, the positive electrode 10 further includes at least one insulating layer 30, and the insulating layer 30 is located on the portion of the current collector 101 located in the empty foil region A3, and the insulating layer 30 is adjacent to the active material layer 102. When the positive electrode 10 has a first active material layer 102a and a second active material layer 102b, the insulating layer 30 can be two, with the two insulating layers 30 arranged on opposite sides of the current collector 101 in the thickness direction. The insulating layer 30 is used to prevent the active material layer 102 of the positive electrode 10 from directly contacting other structural layers, reducing the risk of short circuits inside the cell, and improving the reliability and safety of the cell. The current collector 101 can be a metal foil, such as aluminum foil.

[0069] In some embodiments, the insulating layer 30 may be a ceramic layer, an insulating adhesive layer, or other insulating material layer.

[0070] In some embodiments, the positive electrode 10 includes at least one of zebra-coated positive electrode 10, zebra-patterned intermittent coating positive electrode 10, and zigzag-patterned positive electrode 10.

[0071] In some embodiments, the positive electrode 10 further includes at least one tab structure, which can be obtained by cutting the current collector 101 in the empty foil region A3.

[0072] This application provides a lithium-ion battery, which includes the positive electrode 10 as described above.

[0073] In some embodiments, the lithium-ion battery includes at least one of a multi-tab structure and a stacked structure.

[0074] This application provides an electronic device, which includes a lithium-ion battery as described above.

[0075] Next, the positive electrode and lithium-ion battery provided in this application will be illustrated with specific embodiments and test data. It should be noted that the battery capacity designed in the following embodiments and comparative examples is 5Ah, with a charging cutoff voltage of 4.5V and a discharging cutoff voltage of 3.0V.

[0076] Example 1

[0077] Please refer to the following: Figure 6 This embodiment provides a positive electrode sheet, which is a zebra continuous coating positive electrode sheet. The positive electrode sheet includes a current collector, a first active material layer, a second active material layer, and two insulating layers. In the thickness direction, the first active material layer and the second active material layer are arranged on opposite sides of the current collector, and the two insulating layers are respectively adjacent to the first active material layer and the second active material layer.

[0078] Specifically, the length of the current collector is 15 mm longer than the length of the first active material layer. The edge region of the first active material layer is aligned with the edge region of the second active material layer, and the length of the edge region is 10 mm, while the thickness of the main body region is 88 μm. The edge region has multiple decorative structures, which are deformation-type decorative structures formed by an embossing process. The orthographic projection of the decorative structure on the extension plane is circular. The multiple decorative structures are arranged in an array, and the height of the multiple decorative structures increases sequentially (stepwise) in the direction away from the main body region, while the diameter (or width) remains consistent. Among the multiple decorative structures, the maximum height is 7 μm, the minimum height is 1 μm, the diameter is 0.5 mm, and the spacing between any two adjacent decorative structures is 1 mm.

[0079] The lithium-ion battery in this embodiment is a stacked structure battery made using the positive electrode sheet of this embodiment.

[0080] It should be noted that, Figure 6 In the positive electrode structure shown, in the direction away from the main body region, the diameters (or widths) of multiple modification structures increase sequentially, and the spacing between adjacent modification structures gradually increases. Therefore, regarding the modification structures, this embodiment is only for reference. Figure 6 The shape of the modified structure is not taken into account, but rather the arrangement and size are taken into account.

[0081] Example 2

[0082] The positive electrode sheet in this embodiment has a structure that is basically the same as that in embodiment 1, except that: in this embodiment, the maximum height of the multiple modified structures is 9 μm, the diameter is 1 mm, and the spacing between any two adjacent modified structures is 1.5 mm.

[0083] The lithium-ion battery in this embodiment is a stacked structure battery made using the positive electrode sheet of this embodiment.

[0084] Example 3

[0085] The positive electrode sheet in this embodiment has a structure that is basically the same as that in embodiment 1. The difference is that in this embodiment, the height of the multiple modified structures is consistent (non-stepped), the height is 7μm, the diameter is 1.0mm, and the spacing between any two adjacent modified structures is 1.5mm.

[0086] The lithium-ion battery in this embodiment is a stacked structure battery made using the positive electrode sheet of this embodiment.

[0087] Example 4

[0088] The positive electrode sheet in this embodiment has a structure that is basically the same as that described in Embodiment 1, except that: in this embodiment, the length of the edge region is 12 mm and the thickness of the main body region is 98 μm. The height of the multiple modified structures is consistent (non-stepped), with a height of 7 μm and a diameter of 1.5 mm, and the spacing between any two adjacent modified structures is 2.5 mm.

[0089] The lithium-ion battery in this embodiment is a stacked structure battery made using the positive electrode sheet of this embodiment.

[0090] Example 5

[0091] The positive electrode sheet in this embodiment has a structure that is basically the same as that described in Embodiment 1, except that: in this embodiment, the length of the edge region is 12 mm and the thickness of the main body region is 98 μm. The height of the multiple modified structures is consistent, with a height value of 7 μm (non-stepped), a diameter of 1.5 mm, and a spacing of 2.5 mm between any two adjacent modified structures.

[0092] The lithium-ion battery in this embodiment is a multi-tab structure battery made using the positive electrode sheet of this embodiment.

[0093] Example 6

[0094] The positive electrode sheet in this embodiment has a basically the same structure as the positive electrode sheet described in Embodiment 1, except that: in this embodiment, the length of the edge region is 12 mm, and the thickness of the main body region is 98 μm. Among the multiple modified structures, the maximum height is 9 μm, the minimum height is 2 μm, the diameter is 2 mm, and the spacing between any two adjacent modified structures is 4.0 mm.

[0095] The lithium-ion battery in this embodiment is a multi-tab structure battery made using the positive electrode sheet of this embodiment.

[0096] Example 7

[0097] The positive electrode sheet in this embodiment has a structure that is basically the same as that in Embodiment 1, except that: in this embodiment, the length of the edge region is 12 mm and the thickness of the main body region is 103 μm. Among the multiple modified structures, the maximum height is 7 μm, the minimum height is 4 μm (stepped), the diameter is 1 mm, and the spacing between any two adjacent modified structures is 2.0 mm.

[0098] The lithium-ion battery in this embodiment is a multi-tab structure battery made using the positive electrode sheet of this embodiment.

[0099] Example 8

[0100] Please see Figure 2 The positive electrode sheet in this embodiment has a structure that is basically the same as that described in Embodiment 1, except that: in this embodiment, the length of the edge region is 12 mm and the thickness of the main body region is 98 μm. The maximum height of the plurality of modified structures is 7 μm, the minimum height is 4 μm (stepped), the diameter is 1.5 mm, and the spacing between any two adjacent modified structures is 3.0 mm.

[0101] The lithium-ion battery in this embodiment is a stacked structure battery made using the positive electrode sheet of this embodiment.

[0102] Example 9

[0103] The positive electrode sheet in this embodiment has a structure that is basically the same as that described in Embodiment 1, except that: in this embodiment, the length of the edge region is 12 mm and the thickness of the main body region is 98 μm. The height of the multiple modified structures is consistent, with a height value of 6 μm (non-stepped), a diameter of 2.0 mm, and a spacing of 4.0 mm between any two adjacent modified structures.

[0104] The lithium-ion battery in this embodiment is a stacked structure battery made using the positive electrode sheet of this embodiment.

[0105] Example 10

[0106] like Figure 3As shown, the positive electrode sheet in this embodiment has a structure that is basically the same as that in Embodiment 1, except that: in this embodiment, the length of the edge region is 12 mm and the thickness of the main body region is 98 μm. The modification structure is a compensation modification structure formed by a dot coating process. The orthographic projection of the modification structure on the extension plane is elliptical. Among the multiple modification structures, the maximum height is 7 μm, the minimum height is 2 μm (stepped), the width is 2 mm, and the spacing between any two adjacent modification structures is 3.0 mm. The modification structure is present on both the first active material layer and the second active material layer, and the modification structures on the first active material layer and the modification structures on the second active material layer are aligned and distributed.

[0107] The lithium-ion battery in this embodiment is a stacked structure battery made using the positive electrode sheet of this embodiment.

[0108] Example 11

[0109] like Figure 5 As shown, the positive electrode sheet in this embodiment has a structure that is basically the same as that in Embodiment 1, except that: in this embodiment, the length of the edge region is 12 mm and the thickness of the main body region is 98 μm. In the edge region, some of the modification structures are deformation-type modification structures formed by embossing (these modification structures protrude from the current collector towards the second active material layer), and some modification structures are compensation-type modification structures formed by dot coating (these modification structures are located on the first active material layer). The modification units can be formed by first embossing and then dot coating. The orthographic projection of the modification structure on the extension plane is elliptical. Among the multiple modification structures, the maximum height is 7 μm, the minimum height is 2 μm (stepped), the width is 1 mm, and the spacing between any two adjacent modification structures is 2.0 mm.

[0110] The lithium-ion battery in this embodiment is a stacked structure battery made using the positive electrode sheet of this embodiment.

[0111] Example 12

[0112] like Figure 4As shown, the positive electrode sheet in this embodiment has a structure that is basically the same as that in Embodiment 1, except that: in this embodiment, the length of the edge region is 12 mm and the thickness of the main body region is 98 μm. In the edge region, the modification structure is a compensating modification structure formed by a dot-coating process. The orthographic projection of the modification structure on the extension plane is elliptical. Among the multiple modification structures, the maximum height is 7 μm, the minimum height is 3 μm (stepped), the width is 1 mm, and the spacing between any two adjacent modification structures is 2.0 mm. The modification structure is present on both the first active material layer and the second active material layer, and the modification structures on the first active material layer and the second active material layer are staggered.

[0113] The lithium-ion battery in this embodiment is a stacked structure battery made using the positive electrode sheet of this embodiment.

[0114] Comparative Example 1

[0115] The battery design process, raw materials, and production steps adopted in Comparative Example 1 are basically the same as those in Example 1. The only difference is that the positive electrode sheet included in the battery is different. In Comparative Example 1, a zebra continuous coating positive electrode sheet is used, and the positive electrode sheet does not have the modification units included in the positive electrode sheet described in the embodiments of this application.

[0116] Comparative Example 2

[0117] The battery design process, raw materials, and production steps adopted in Comparative Example 2 and Example 5 are basically the same. The only difference is that the positive electrode sheet included in the battery is different. In Comparative Example 1, a zebra continuous coating positive electrode sheet is used, and the positive electrode sheet does not have the modification units included in the positive electrode sheet described in the embodiments of this application.

[0118] Next, the performance of several batteries described in Examples 1 to 12 and Comparative Examples 1 to 2 will be compared using test data.

[0119] Please refer to Table 1, which shows the test data of some performance parameters of the batteries in Examples 1-12 and Comparative Examples 1-2. The performance parameters include energy density, capacity retention rate after 1000 cycles at 25°C, expansion rate after 1000 cycles at 25°C, capacity retention rate after 600 cycles at 45°C, expansion rate after 1600 cycles at 45°C, percentage of residual capacity after 30 days of storage at 60°C, percentage of recovered capacity after 30 days of storage at 60°C, percentage of residual capacity after 18 hours of storage at 85°C, and percentage of recovered capacity after 18 hours of storage at 85°C.

[0120] Based on the information shown in Table 1, the lithium-ion battery provided in this application embodiment has the following advantages:

[0121] Firstly, the energy density is improved. The reason for the improved energy density of the lithium-ion battery provided in this application embodiment is that, based on the arrangement of the modification unit, the edge region of the positive electrode can be modified. On the one hand, the active material located in the edge region can be fully utilized, thereby improving the battery capacity. On the other hand, the overall flatness of the cell assembled based on the modified positive electrode is better (the overall thickness is reduced by about 20 μm compared to traditional cells), resulting in an improvement of energy density of about 0.8%.

[0122] Secondly, the cycle performance is significantly improved. Specifically, after 1000 cycles at room temperature (25°C), the lithium-ion batteries of Examples 1-12 show a capacity retention rate increase of >4.5% and a swelling rate decrease of approximately 3.5% compared to Comparative Examples 1-2. After 600 cycles at high temperature (45°C), the lithium-ion batteries of Examples 1-12 show a capacity retention rate increase of >3.0% and a swelling rate decrease of approximately 1.0% compared to Comparative Examples 1-2. In other words, regardless of whether it is long-term cycling at room temperature or long-term cycling at high temperature, the long-term cycle life of the lithium-ion batteries provided in this application's embodiments shows a significant improvement as shown in the attached figures.

[0123] The reason why the cycle performance of the lithium-ion battery provided in this application embodiment is improved is that: based on the arrangement of the modification unit, an uneven texture is formed on the surface of the positive electrode sheet, which effectively compensates for the thickness difference caused by the accumulation of the edge area of ​​the positive electrode sheet in the area where the cell head is located. This increases the contact area between the positive electrode sheets at the cell head during the pressing process, ensures the bonding consistency between the positive electrode sheet and the separator, and prevents obvious bridge breakage between the electrodes in the later stage of the cycle process, thus ensuring the cycle performance.

[0124] Third, the storage performance has been improved. Specifically, whether it is high-temperature storage at 85 degrees for 18 hours or high-temperature storage at 60 degrees for 30 days, Examples 1 to 12 show higher residual capacity and recovery capacity compared to Comparative Examples 1 to 2. The improved storage performance of the lithium-ion battery provided in this application is also due to the good consistency of the electrode interface inside the cell.

[0125] Table 1

[0126]

[0127] Please see Figure 7 , Figure 7 A comparison diagram of the thickness distribution of the lithium-ion batteries described in Examples 1-12 and Comparative Examples 1-2 in a half-charge state is shown. Compared with Comparative Examples 1-2, the batteries in Examples 1-12 are significantly thinner. With other structural and state parameters remaining the same, this indicates that the modification unit step in the positive electrode sheet of this application is beneficial for reducing battery thickness. Furthermore, based on... Figure 7As can also be seen from the content shown, compared with comparative examples 1 to 2, the cell thickness distribution range of Examples 1 to 12 is narrower, that is, the overall thickness distribution of the cell is more consistent.

[0128] In summary, the irregularly shaped coated positive electrode of this application, by arranging modification units in the thinner edge region of the positive electrode, modifies the edge region to reduce the thickness difference between the active material layer in the edge region and the active material layer in the main region. This reduction in thickness difference achieves the following beneficial effects: it helps increase the contact area between the internal electrode and the separator during the pressing process, ensuring consistent adhesion between different regions of the electrode and the separator, avoiding gaps between the edge region and the separator, reducing the risk of lithium plating in the edge region, and increasing the cycle life of the battery. Based on the thickness modification of the edge region, the stress on each region of the battery is more uniform during the pressing process, resulting in a more uniform overall thickness distribution of the battery and reducing the average thickness of the battery during mass production (by approximately 20 μm). Through structural modification of the edge region, the active material in the edge region can be fully utilized, helping to reduce the internal resistance of the battery, improve current transmission consistency, and increase the energy density of the battery. Furthermore, by designing the arrangement, size, and spacing of the modification structures within the modification unit, the heat distribution and diffusion rate within the cell can be more uniformly controlled, reducing the safety risks of the battery under abnormal conditions such as overcharging, over-discharging, and short circuits. Based on the aforementioned positive electrode arrangement, the lithium-ion battery of this application exhibits improved cycle life, energy density, and safety performance. The electronic device, based on the configuration of the aforementioned lithium-ion battery, demonstrates improved reliability and operational performance. Therefore, this application effectively overcomes various shortcomings of the prior art and possesses high industrial applicability.

[0129] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. An improved irregularly shaped coated positive electrode sheet, characterized in that, The electrode includes a current collector and at least one active material layer, the active material layer being located on the current collector. The improved irregularly shaped coated positive electrode is divided into a main region and an edge region along its length. The thickness of the portion of the active material layer located in the edge region is less than the thickness of the portion of the active material layer located in the main region. The edge region has a decorative unit, and the decorative unit includes at least one decorative structure that protrudes in the thickness direction along a direction away from the extension plane of the portion of the current collector located in the main region.

2. The improved irregularly shaped coated positive electrode sheet according to claim 1, characterized in that: The modified structure includes at least one of a deformation-type modified structure and a compensation-type modified structure; wherein, the deformation-type modified structure is formed by local deformation of the current collector and the active material layer, and the compensation-type modified structure is formed by active material units located on the side of the active material layer away from the current collector.

3. The improved irregularly shaped coated positive electrode sheet according to claim 2, characterized in that: The improved irregularly shaped coated positive electrode includes a first active material layer and a second active material layer, which are located on opposite sides of the current collector in the thickness direction.

4. The improved irregularly shaped coated positive electrode sheet according to claim 3, characterized in that: The first active material layer and the second active material layer are both provided with the compensation modification structure; wherein, the compensation modification structure on the first active material layer and the compensation modification structure on the second active material layer are aligned; or, the compensation modification structure on the first active material layer and the compensation modification structure on the second active material layer are staggered. Alternatively, one of the first active material layer and the second active material may have the compensation modification structure, and the edge region may also have the deformation modification structure; Alternatively, the edge region may have only the deformable modification structure, all of which protrude in the same direction, or at least two of which protrude in different directions.

5. The improved irregularly shaped coated positive electrode sheet according to any one of claims 1-4, characterized in that, The percentage between the height of the modified structure and the thickness of the portion of the improved irregularly shaped coated positive electrode sheet located in the main region ranges from 1% to 30%; and / or, The ratio between the height and width of the decorative structure is in the range of 0.0007 to 0.

03.

6. The improved irregularly shaped coated positive electrode sheet according to any one of claims 1-4, characterized in that: The edge region includes multiple of the aforementioned decorative structures; wherein... The multiple modified structures are arranged in an array, or the multiple modified structures are irregularly distributed; and / or, The multiple decorative structures have the same size, or the sizes of the multiple decorative structures increase in a direction away from the main body region; wherein the size includes at least one of width, height and length.

7. The improved irregularly shaped coated positive electrode sheet according to claim 6, characterized in that, The length of the edge region is less than or equal to 20 mm; and / or, The thickness of the portion of the improved irregularly shaped coated positive electrode sheet located in the main region ranges from 40 μm to 200 μm; and / or, The height of the modified structure is less than or equal to 100 μm; and / or, The width of the modified structure ranges from 0.1 mm to 5 mm; and / or, The spacing between any two adjacent modified structures ranges from 0.1 mm to 7 mm.

8. The improved irregularly shaped coated positive electrode sheet according to claim 1, characterized in that: The improved irregularly shaped coated positive electrode sheet includes at least one of zebra-coated positive electrode sheet, grid-patterned zebra intermittently coated positive electrode sheet, and square-shaped coated positive electrode sheet; and / or, The orthographic projection of the modified structure onto the extended plane is at least one of the following: straight line, wavy line, broken line, curved line, circle, polygon, heart shape, teardrop shape, fan shape, and irregular shape.

9. A lithium-ion battery, characterized in that: The lithium-ion battery includes the improved irregularly shaped coated positive electrode sheet as described in any one of claims 1 to 8.

10. An electronic device, characterized in that: The electronic device includes the lithium-ion battery as described in claim 9.

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