A positive electrode sheet, a roll core structure, and an electric device

Abstract

The application relates to the battery technical field, and provides a positive plate, a roll core structure and an electric equipment. The positive plate comprises a positive plate body, the positive plate body comprises an intermediate structure and an end structure, a first coating layer of the intermediate structure has a first thickness, a first coating layer of the end structure has a second thickness, the second thickness of the first coating layer of the end structure is smaller than the first thickness of the first coating layer of the intermediate structure, the positive plate further comprises an insulating layer, the insulating layer is arranged at one end in a width direction of the positive current collector, and the insulating layer is covered by the first coating layer and / or the second coating layer. The embodiment of the application can improve the safety and comprehensive performance of the roll core structure.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a positive electrode sheet, a winding structure, and an electrical device. Background Technology

[0002] Lithium plating in battery cells has a significant impact on their safety and overall performance. Currently, positive and negative electrode plates are typically designed with uniform thickness, meaning both the positive and negative electrode plates have the same thickness along their width. This structural design of the positive and negative electrode plates easily leads to lithium plating in the battery cell, and this plating often occurs at the edges of the positive or negative electrode plates, resulting in low safety and poor overall performance of the battery cell. Summary of the Invention

[0003] This application provides a positive electrode sheet, a wound core structure, and an electrical device, which can improve the safety and overall performance of the wound core structure.

[0004] The first aspect of this application provides a positive electrode sheet, comprising:

[0005] A positive electrode body, the positive electrode body comprising an intermediate structure and an end structure;

[0006] The positive electrode body includes:

[0007] A positive electrode current collector has a first connecting surface and a second connecting surface, as well as a first end and a second end along the length direction of the positive electrode current collector.

[0008] A first coating layer is formed on the first connection surface of the positive electrode current collector;

[0009] And a second coating layer, formed on the second connection surface of the positive electrode current collector,

[0010] The first coating layer includes a first layer and a second layer, and the second coating layer includes a third layer and a fourth layer.

[0011] Wherein, the first coating layer of the intermediate structure has a first thickness, the first coating layer of the end structure has a second thickness, and the second thickness of the first coating layer of the end structure is less than the first thickness of the first coating layer of the intermediate structure;

[0012] The positive electrode sheet further includes an insulating layer disposed at one end of the positive electrode current collector in the width direction, and the insulating layer is covered by the first coating layer and / or the second coating layer.

[0013] According to the positive electrode sheet described in the first direction, by designing the thickness of the end structure to be less than the thickness of the middle structure, the region on the negative electrode sheet corresponding to the end structure can provide sufficient lithium-ion active insertion sites, thus avoiding lithium plating and improving the safety and overall performance of the cell structure. Simultaneously, by providing an insulating layer, burrs can be prevented during the die-cutting of the positive electrode sheet, thereby protecting the positive electrode sheet.

[0014] In one possible implementation, a first end structure is formed on the region adjacent to the first end of the first coating layer. The length of the first end structure is L1, and the thickness of the first end structure is H1. The thickness of the first coating layer of the intermediate structure is H, and H1 and H satisfy the relationship: H1-H = -15μm to 0μm; and / or,

[0015] A second end structure is formed in the region adjacent to the first end on the second coating layer. The length of the second end structure is L2, and the thickness of the second end structure is H2. A third end structure is formed in the region adjacent to the second end structure on the second coating layer. The length of the third end structure is L3, and the thickness of the third end structure is H3. H2 and H satisfy the relationship: H2-H = -15μm to -1μm, and / or H3 and H satisfy the relationship: H3-H = -15μm to -1μm.

[0016] In one possible implementation, according to claim 2, the positive electrode sheet is characterized in that a fourth end structure is formed in the region adjacent to the second end on the first coating layer, the fourth end structure having a length of L4 and a thickness of H4; a fifth end structure is formed in the region adjacent to the fourth end structure on the first coating layer, the fifth end structure having a length of L5 and a thickness of H5; H4 and H satisfy the relationship: H4-H = -15μm to -1μm, and / or H5 and H satisfy the relationship: H5-H = -6μm to -0μm; and / or,

[0017] A sixth end structure is formed in the region adjacent to the second end on the second coating layer. The length of the sixth end structure is L6 and the thickness of the sixth end structure is H6. H6 and H satisfy the relationship H6-H=-15μm~0μm.

[0018] In one possible implementation, at the first end, the first and second layers are flush, the third and fourth layers are flush, and / or, at the second end, the first and second layers form a tip, and / or, the third and fourth layers form a tip.

[0019] In one possible implementation, at the tip, the first layer covers the second layer, or the first layer is flush with the second layer, or the second layer extends beyond the first layer by a length L7, where L7 satisfies the relationship: L7≤2mm;

[0020] And / or, at the tip, the fourth layer covers the third layer, or the fourth layer is flush with the third layer, or the fourth layer extends beyond the third layer by a length of L8, where L8 satisfies the relationship: L8≤2mm.

[0021] In one possible implementation, both the first and second layers cover the insulating layer, and both the third and fourth layers cover the insulating layer.

[0022] In one possible implementation, an overlapping region is formed on the insulating layer that overlaps with the first layer and the second layer. The length of the overlapping region is W1. The overlapping region includes a first overlapping region formed by the first layer and the insulating layer and a second overlapping region formed by the second layer and the insulating layer. The length of the first overlapping region is W2, and the length of the second overlapping region is W3. W1, W2, and W3 satisfy the following relationships: W1 = W2 + W3, and / or W3 / W1 = 0 to 0.75.

[0023] In one possible implementation, the length of the insulating layer is W20, and a non-overlapping region is formed on the insulating layer, the length of the non-overlapping region being W4, and W1 and W20 satisfying the relationship: W1 / W20 = 1 / 300 to 1 / 2.

[0024] In one possible implementation, a non-tab region is formed on the positive current collector, wherein the length of the insulating layer in the non-tab region is W30, the length of the non-overlapping region is W5, and W4 and W5 satisfy the relationship: W5 / W4 = 0.2 to 0.8.

[0025] In one possible implementation, the insulating layer covers the first layer, the second layer covers the insulating layer, the insulating layer covers the fourth layer, and the third layer covers the insulating layer.

[0026] In one possible implementation, an overlapping region is formed on the insulating layer that overlaps with the first layer and the second layer, the length of the overlapping region being W9, the overlapping region including a third overlapping region formed by the second layer and the insulating layer, the length of the third overlapping region being W10, and W9 and W10 satisfying the relationship: W10 / W9 = 0.08~0.75.

[0027] A second aspect of this application provides a core structure, comprising:

[0028] The positive electrode sheet as described in the first aspect;

[0029] Negative electrode plate;

[0030] And a separator, the separator being disposed between the positive electrode and the negative electrode.

[0031] According to the core structure described in the second aspect of this application, the core structure has excellent safety performance and overall performance.

[0032] In one possible implementation, the negative electrode includes a negative electrode body, the negative electrode body comprising:

[0033] The negative electrode current collector has a third connecting surface and a fourth connecting surface, as well as a third end and a fourth end along the length direction of the negative electrode current collector;

[0034] A third coating layer is formed on the third connection surface of the negative electrode current collector;

[0035] And a fourth coating layer, formed on the fourth connection surface of the negative electrode current collector.

[0036] Wherein, the negative electrode current collector, the third coating layer and the fourth coating layer are flush at the third end to form a flush end, and the negative electrode current collector, the third coating layer and the fourth coating layer are not flush at the fourth end to form a non-flush end.

[0037] In one possible implementation, a first region and a second region are formed on the third coating layer and the fourth coating layer. The distance between the first region and the third end or the fourth end is S1, and the thickness of the first region is V1. The distance between the second region and the third end or the fourth end is S2, and the thickness of the second region is V2. S1, S2, V1 and V2 satisfy the following relationship: S1≥50mm, V2-V1=-3μm~7μm.

[0038] In one possible implementation, the third coating layer includes a fifth and a sixth layer, and the fourth coating layer includes a seventh and an eighth layer. At the third end, the fifth and sixth layers form a tip, and the seventh and eighth layers form a tip. At the fourth end, the fifth and sixth layers form a tip, and the seventh and eighth layers form a tip.

[0039] In one possible implementation, at the tip, the fifth layer covers the sixth layer, or the fifth layer is flush with the sixth layer, or the sixth layer extends beyond the fifth layer by a length of S3, where S3 satisfies the relationship: S3≤2mm.

[0040] In one possible implementation, the positive electrode sheet is formed with a flush end along the winding direction of the core structure, the flush end being located at the innermost side of the core structure and in a straight section.

[0041] In one possible implementation, the negative electrode includes a first loop structure located inside the core structure, the side of the first loop structure facing the positive electrode including a single-sided coating layer, the end of which does not extend beyond the centerline of the core structure.

[0042] A third aspect of this application provides an electrical device including the core structure described in the second aspect. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A cross-sectional view of a core structure provided according to an embodiment of this application is shown;

[0045] Figure 2 A schematic diagram of a straight section of a core structure provided according to an embodiment of this application is shown;

[0046] Figure 3 A cross-sectional view along the length of a positive electrode sheet provided according to an embodiment of this application is shown;

[0047] Figure 4 A schematic diagram of a combined structure of a first layer and a second layer according to an embodiment of this application is shown;

[0048] Figure 5 A schematic diagram of another combined structure of the first layer and the second layer provided according to an embodiment of this application is shown;

[0049] Figure 6 A schematic diagram of another combination structure of the first layer and the second layer provided according to an embodiment of this application is shown;

[0050] Figure 7 A cross-sectional view along the width direction of a positive electrode sheet provided according to an embodiment of this application is shown;

[0051] Figure 8 A cross-sectional view along the width direction of the first coating layer of a positive electrode sheet provided according to an embodiment of this application is shown;

[0052] Figure 9 Another cross-sectional view along the width direction of a positive electrode sheet provided according to an embodiment of this application is shown;

[0053] Figure 10 Another cross-sectional view along the width direction of the first coating layer of a positive electrode sheet provided according to an embodiment of this application is shown;

[0054] Figure 11 A cross-sectional view along the length of a negative electrode sheet provided according to an embodiment of this application is shown;

[0055] Figure 12 A cross-sectional view along the width direction of a negative electrode sheet provided according to an embodiment of this application is shown;

[0056] Figure 13 A cross-sectional view along the width direction of another negative electrode sheet provided according to an embodiment of this application is shown.

[0057] Figure label:

[0058] 100 - Positive electrode body; 101 - Intermediate structure; 102 - End structure; 110 - Positive current collector; 120 - First coating layer; 130 - Second coating layer; 111 - First connecting surface; 112 - Second connecting surface; 113 - First end; 114 - Second end; 121 - First layer; 122 - Second layer; 131 - Third layer; 132 - Fourth layer; 1021 - First end structure; 1022 - Second end structure; 1023 - Third end structure; 1024 - Fourth end structure; 1025 - Fifth end structure; 1026 - Sixth end structure;

[0059] 200 - Negative electrode body; 210 - Negative electrode current collector; 220 - Third coating layer; 230 - Fourth coating layer; 211 - Third connecting surface; 212 - Fourth connecting surface; 213 - Third end; 214 - Fourth end; 215 - Fifth end; 216 - Sixth end; 221 - Fifth layer; 222 - Sixth layer; 231 - Seventh layer; 232 - Eighth layer;

[0060] 300 - Insulating layer; 310 - Overlapping region; 320 - Non-overlapping region; 330 - First insulating layer; 340 - Second insulating layer; 311 - First overlapping region; 312 - Second overlapping region; 313 - Third overlapping region;

[0061] 10-Positive electrode sheet; 11-Adhesive-coated section; 21-Bending section; 22-First ring structure; 23-Single-sided coating layer; a-Flush end; b-Middle region; c-Straight section; d-Circular section; e-Non-flush end; f-Tip; g-First region; h-Second region;

[0062] 20-Negative electrode;

[0063] 30-Septum. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0065] With the development of new energy technologies, batteries are being used more and more widely. Batteries have high energy density, high safety, long service life, and green environmental protection, and have been widely used in passenger cars, commercial vehicles, electric bicycles, heavy trucks, energy storage facilities, battery swapping stations, engineering manufacturing, intelligent equipment and other fields. At the same time, they are also promoting the continuous development of communication terminals, medical devices, energy development and other aspects.

[0066] As the basic building block of a battery, the performance of the battery cell significantly impacts the overall performance of the battery. A battery cell consists of a positive electrode, a negative electrode, and a separator between the positive and negative electrodes. The positive electrode typically includes aluminum foil and an active material layer coated on the surface of the aluminum foil. The negative electrode typically includes copper foil and an active material embedding layer coated on the surface of the copper foil. Active materials in the active material layer can embed into this embedding layer. The battery cell releases or stores electrical energy through the interaction of these active materials between the active material layer and the embedding layer. In this interaction process, the more active materials present, the more electrical energy the cell can release or store, indicating a larger capacity.

[0067] In lithium-ion battery cells, the active material in the active material layer refers to lithium ions. When lithium ions in the cell cannot be intercalated into the active material intercalation layer, the excess lithium ions will overflow, resulting in lithium plating. This can lead to safety accidents such as cell explosions, or affect the cell's charge / discharge rate, cycle life, and energy density, thus impacting the cell's overall performance. In short, lithium plating has a significant impact on the safety and overall performance of battery cells.

[0068] In wound-core structures, the positive and negative electrode sheets in related technologies typically employ a design approach with uniform thickness, meaning both the positive and negative electrode sheets have a consistent thickness along their width. This uniform thickness design leads to a situation where, when the positive and negative electrode sheets are combined to form a wound or stacked structure, lithium ions on the positive electrode often fail to properly intercalate onto the negative electrode due to insufficient active intercalation sites, resulting in lithium plating. This plating phenomenon usually occurs at the edges of either the positive or negative electrode sheet. The reason is that, according to the migration direction of lithium ions, they need to migrate from the positive to the negative electrode sheet. This migration path easily leads to lithium ion accumulation at the edges of the positive electrode sheet; more specifically, lithium ions tend to accumulate in the end edge region of the positive electrode sheet. When the positive and negative electrode sheets are designed with uniform thickness, the end edge region of the negative electrode sheet relative to the positive electrode sheet cannot provide sufficient active intercalation sites for lithium ions, causing lithium plating to frequently occur at the edges of either the positive or negative electrode sheet.

[0069] The design concepts of the positive and negative electrodes in related technologies lead to low safety and poor overall performance of the battery cells.

[0070] Based on the above-mentioned situation and problems, this application provides a positive electrode sheet. Using the positive electrode sheet to form a battery cell (which can be a wound core structure), lithium ions are more easily embedded into the negative electrode sheet, thereby improving the safety and overall performance of the battery cell.

[0071] In this embodiment, the positive electrode has an end structure that differs from that in conventional technology. The end structure is designed to be thinner than other parts of the positive electrode. The negative electrode corresponding to the end structure can provide more lithium-ion active insertion sites, thereby making it easier for lithium ions to detach from the end structure and insert into the negative electrode.

[0072] Based on this positive electrode sheet, embodiments of this application also provide a core structure, which has excellent overall performance and safety performance.

[0073] In the embodiments of this application, the above-mentioned performance of the core structure can be achieved by reasonably setting the positive electrode sheet and its position, reasonably setting the negative electrode sheet and its position, and reasonably setting the relationship between the positive electrode sheet and the negative electrode sheet. In the following embodiments, the structural composition of the core structure will be introduced from three aspects. The first aspect is the overall level of the core structure, which mainly involves the positional relationship between the positive electrode sheet and the negative electrode sheet. The second aspect is the individual level of the positive electrode sheet, which mainly involves the structure of the positive electrode sheet and related processes. The third aspect is the individual level of the negative electrode sheet, which mainly involves the structure of the negative electrode sheet and related processes.

[0074] Figure 1 A cross-sectional view of a core structure provided according to an embodiment of this application is shown.

[0075] In the embodiments of this application, please refer to Figure 1 The core structure includes a negative electrode 20, a separator 30, and the aforementioned positive electrode 10. The separator 30 is disposed between the positive electrode 10 and the negative electrode 20 to form insulation between the positive electrode 10 and the negative electrode 20, thereby preventing a short circuit between the positive electrode 10 and the negative electrode 20.

[0076] The core structure in this embodiment, based on the setting of the positive electrode 10, can avoid lithium plating and has excellent comprehensive performance and safety performance.

[0077] It should be noted that the following embodiments of this application will involve descriptions of relevant directions. To facilitate understanding and consistency in the meaning of each direction, the following will be combined with... Figure 1 Define the directions of the core structure.

[0078] It is understood that the wound core structure is formed by winding the negative electrode sheet 20, the separator 30, and the positive electrode sheet 10. It can be wound into a cylindrical structure or a square structure; this embodiment uses a square structure as an example. During the winding process into a square structure, the positive electrode sheet 10, the negative electrode sheet 20, and the separator 30 are wound clockwise or counterclockwise layer by layer, gradually forming a square structure. It can be understood that the length direction of the positive electrode sheet 10, the negative electrode sheet 20, and the separator 30 corresponds to the winding direction of the wound core structure. After forming the wound core structure, its outer surface includes two opposing planes and an arc surface connecting the two planes. The length and width directions of the wound core structure can be defined using one of the planes as a reference. Figure 1 In the example shown, the X direction represents the winding direction of the core structure, and also the length direction of the positive electrode 10, the negative electrode 20 and the separator 30. The Z direction represents the thickness direction of the core structure, and the width direction Y of the core structure is perpendicular to the X and Z directions.

[0079] In some embodiments, please refer to Figure 1 Along the winding direction of the core structure, the positive electrode sheet 10 has a flush end a, which is located on the innermost side of the core structure and in the straight section c.

[0080] Specifically, the flush end 'a' is the starting end of the positive electrode 10, and this starting end is located within the middle region 'b' of the core structure. For a square structure, the cross-section of the core structure along its length is approximately an elongated oval structure, which includes two straight segments 'c' and an arc segment 'd' connecting the two straight segments 'c'. The flush end 'a' being located at the innermost side of the core structure and within the straight segment 'c' can be understood as the flush end 'a' being positioned within the middle region 'b' and at the connection point between the straight segment 'c' and the arc segment 'd'.

[0081] In the above embodiments, the position design of the flush end a enables the positive electrode 10 to make full use of the space in the middle region b of the winding structure, which is beneficial to improving the volumetric energy density and capacity of the cell.

[0082] Figure 2 A schematic diagram of a straight section of a core structure provided according to an embodiment of this application is shown.

[0083] In some embodiments, please refer to Figure 2 The negative electrode 20 extends beyond the positive electrode 10 by a length of X1, which satisfies the relationship: X1 = 0.2mm ~ 2mm.

[0084] This ensures that the negative electrode 20 covers the positive electrode 10. This coverage extends along the thickness of the cell structure, ensuring that the lithium ions released from the positive electrode 10 have sufficient active insertion sites on the negative electrode 20. This prevents lithium plating on the negative electrode 20, thus guaranteeing the safety of the core structure. In specific designs, X1 can be 0.2mm, 1mm, or 2mm.

[0085] In some embodiments, please refer to Figure 2 The diaphragm 30 extends out of the negative electrode plate 20 and the length of the extension is X2, which satisfies the relationship: X2 = 0.5mm ~ 2mm.

[0086] This ensures that the separator 30 covers the positive electrode 10 and the negative electrode 20. This coverage extends along the thickness of the cell structure, preventing short circuits in the negative electrode 20 and guaranteeing the safety of the wound core structure. In specific designs, X2 can be 0.5mm, 1mm, or 2mm.

[0087] In some embodiments, please refer to Figure 1 The positive electrode 10 has an adhesive portion 11 at its end along the winding direction, and the end of the negative electrode 20 extends beyond the end of the positive electrode 10 by a length of X3, which satisfies the relationship: X3≥2mm.

[0088] Specifically, at the starting end of the positive electrode 10, i.e., the aforementioned end a, an adhesive-coated portion 11 is formed. Within the middle region b of the winding structure, the negative electrode 20, corresponding to the adhesive-coated portion 11, needs to extend beyond the adhesive-coated portion 11. For example, in… Figure 1In the example shown, the negative electrode 20 is wound from the starting end and forms a bend 21 at the position corresponding to the adhesive portion 11. This bend 21 needs to extend beyond the adhesive portion 11. Designing X3 to the above dimensions ensures that there is a misalignment distance between the end of the negative electrode 20 and the end of the positive electrode 10. This ensures that the negative electrode 20 has sufficient space to correspond to the end of the positive electrode 10, ensuring that the lithium-ion transport efficiency is basically consistent and that there are enough lithium-ion active insertion sites. This also ensures that the negative electrode 20 will not deposit lithium, thereby improving the safety and overall performance of the wound structure.

[0089] In some embodiments, the negative electrode 20 includes a first loop structure 22 located inside the core structure, the side of the first loop structure 22 facing the positive electrode 10 including a single-sided coating layer 23, the end of the single-sided coating layer 23 not exceeding the center line of the core structure.

[0090] exist Figure 1 In the example shown, the negative electrode 20 is located in the innermost layer of the core structure. The first loop structure formed by the negative electrode 20 along the winding direction is the first loop structure 22 mentioned above. The first loop structure 22 includes the starting end of the negative electrode 20 and the bending portion 21 mentioned above. The positive electrode 10 is located on one side of the negative electrode 20. Therefore, a single-sided coating layer 23 corresponding to the positive electrode 10 is formed on the negative electrode 20. The single-sided coating layer 23 is one of the active material embedding layers mentioned above. It can be made of materials such as ink, silicon carbon, silicon oxide, and pure silicon. The end of the single-sided coating layer 23 does not exceed the center line of the core structure. As a result, the volumetric energy density of the battery can be improved.

[0091] The above embodiments have described the core structure in detail from a first aspect. As can be seen from these embodiments, the core structure in this application can effectively improve the safety and overall performance of the core structure by rationally designing the arrangement of the positive electrode 10 and the negative electrode 20. The following embodiments will describe the structural composition of the core structure from a second aspect.

[0092] Figure 3 A cross-sectional view along the length of a positive electrode sheet according to an embodiment of this application is shown. Please refer to... Figure 3 In this embodiment of the application, the positive electrode 10 includes a positive electrode body 100, which includes an intermediate structure 101 and an end structure 102. The first coating layer of the intermediate structure has a first thickness, and the first coating layer of the end structure has a second thickness. The second thickness of the first coating layer of the end structure is less than the first thickness of the first coating layer of the intermediate structure.

[0093] Taking a square structure as an example, when the core structure is square, the positive electrode body 100 has four edges. It can be understood that the end structure 102 can be formed on these four edges, or on some of the edges. The part of the positive electrode body 100 excluding the end structure 102 can be understood as the middle structure 101.

[0094] Taking the coordinate system in 3 as an example, the first thickness and the second thickness are both dimensions in the Z direction. The second thickness being less than the first thickness indicates that the dimension of the first coating layer of the end structure 102 in the Z direction is less than the dimension of the first coating layer of the intermediate structure 101 in the Z direction.

[0095] It should be noted that the positive electrode 10 and the negative electrode 20 usually need to go through a coating process during production. The corresponding adhesive needs to be applied to the appropriate position through the die to form the positive electrode 10 and the negative electrode 20. During the coating process, the thickness of the positive electrode 10 and the negative electrode 20 will fluctuate (even with the design idea of ​​consistent thickness, there will be fluctuations).

[0096] In this embodiment, the positive electrode 10 is designed such that the thickness of the first coating layer of the end structure 102 is less than the thickness of the first coating layer of the intermediate structure 101. The area on the negative electrode 20 corresponding to the end structure 102 can provide sufficient lithium-ion active insertion sites, which can avoid the occurrence of lithium plating, thereby improving the safety and overall performance of the cell structure.

[0097] In some embodiments, please refer to Figure 3 The positive electrode 10 includes a positive current collector 110, a first coating layer 120, and a second coating layer 130, with the first coating layer 120 and the second coating layer 130 disposed on the positive current collector 110. The first coating layer 120 and the second coating layer 130 belong to the category of active material layers.

[0098] The positive current collector 110 needs to be in contact with the first coating layer 120 and the second coating layer 130 to achieve the function of collecting current. The positive current collector 110 has a first connecting surface 111 and a second connecting surface 112. The first coating layer 120 is formed on the first connecting surface 111 of the positive current collector 110, and the second coating layer 130 is formed on the second connecting surface 112 of the positive current collector 110.

[0099] The first coating layer 120 can be formed on the positive electrode current collector 110 by coating, and the second coating layer 130 can be formed on the positive electrode current collector 110 by coating.

[0100] Along the length of the positive current collector 110, the positive current collector 110 has a first end 113 and a second end 114. The positive current collector 110, the first coating layer 120 and the second coating layer 130 are flush at the first end 113 to form a flush end a, and the positive current collector 110, the first coating layer 120 and the second coating layer 130 are not flush at the second end 114 to form a non-flush end e.

[0101] During the production process, the positive electrode 10 needs to be die-cut to form two positive electrode sheets 10 on both sides of the die-cutting position. For the two positive electrode sheets 10 formed by die-cutting, one end of each positive electrode sheet 10 will form a flush end a. At this flush end a, the first coating layer 120, the second coating layer 130, and the positive current collector 110 after die-cutting are flush with each other. As mentioned above, this flush end a can be set on the innermost side of the core structure, thereby ensuring the volumetric energy density and capacity of the core structure. On the other hand, when this flush end a is set on the innermost side of the core structure, it can ensure the uniformity of the lithium ion release rate on the innermost side of the core structure, avoiding the problem of different lithium ion release rates of aluminum foil due to uneven ends, thereby avoiding the formation of different stress distributions on both sides of the aluminum foil, and achieving internal protection of the cell structure. For non-flush ends e, the first coating layer 120 and the second coating layer 130 have different lengths. This length matching design of non-flush ends e can make the two sides of the positive electrode sheet 10 have better energy density after bonding.

[0102] In the embodiments of this application, the thickness of the end structure 102 of the positive electrode 10 can be designed in various ways according to different applications. The area size and thickness of the end structure 102 can be designed according to the length of the positive electrode 10. In the following embodiments, multiple end structures 102 will be described one by one. It is understood that in other embodiments, more end structures 102 can be provided. In addition, in order to ensure a balance between energy density and lithium plating efficiency, the end structures 102 located at the first end 113 and the second end 114 of the positive electrode 10 can be designed in a balanced manner. For example, three end structures 102 can be provided at the flush end a, and three end structures 102 can also be provided at the non-flush end e.

[0103] In some embodiments, please refer to Figure 3 The region adjacent to the first end 113 on the first coating layer 120 forms a first end structure 1021. The length of the first end structure 1021 is L1, the thickness of the first end structure 1021 is H1, and the thickness of the first coating layer of the intermediate structure 101 is H. L1 satisfies the relationship: L1 = 0 mm ~ 2 mm, and H1 and H satisfy the relationship: H1 - H = -15 μm ~ 0 μm.

[0104] It should be noted that the value of L1 must be at least greater than 0, for example, it can be 1 mm or 2 mm. By setting L1 between 0 mm and 2 mm, the length of the first end structure 1021 can be reasonably planned. H1-H can be -15 μm, -10 μm, etc. It can be understood that when the value of L1 is large, H1-H can be small. For example, when L1 is 2 mm, H1-H can be -15 μm. This can reasonably balance the length and thickness of the first end structure 1021. The region on the negative electrode 20 corresponding to the first end structure 1021 can provide sufficient lithium-ion active insertion sites, while also allowing the positive electrode 10 to have good strength at the first end structure 1021.

[0105] In some embodiments, please refer to Figure 3 A second end structure 1022 is formed in the region adjacent to the first end 113 on the second coating layer 130. The length of the second end structure 1022 is L2, and the thickness of the second end structure 1022 is H2. A third end structure 1023 is formed in the region adjacent to the second end structure 1022 on the second coating layer 130. The length of the third end structure 1023 is L3, and the thickness of the third end structure 1023 is H3. L2 satisfies the relationship: L2 = 0 mm ~ 5 mm. H2 and H satisfy the relationship: H2 - H = -15 μm ~ -1 μm. L3 satisfies the relationship: L3 = 5 mm ~ 30 mm. H3 and H satisfy the relationship: H3 - H = -15 μm ~ -1 μm.

[0106] It should be noted that the value of L2 must be at least greater than 0, for example, it can be 1mm, 2mm, 5mm, etc. By setting L2 between 0mm and 5mm, the length of the second end structure 1022 can be reasonably planned, and H2-H can be -15μm, -10μm, etc. Understandably, when the value of L2 is larger, H2-H can be smaller. For example, when L2 is 5mm, H2-H can be -15μm. This can reasonably balance the length and thickness of the second end structure 1022. The area on the negative electrode 20 corresponding to the second end structure 1022 can provide sufficient lithium-ion active insertion sites, while also ensuring that the positive electrode 10 has good strength at the second end structure 1022. The value of L3 can be 5mm, 15mm, 30mm, etc. By setting L3 between 5mm and 30mm, the length of the third end structure 1023 can be reasonably planned, and H3-H can be -15μm, -10μm, etc. It is understandable that when L3 is large, H3-H can be small. For example, when L3 is 30mm, H3-H can be -15μm. This can reasonably balance the length and thickness of the third end structure 1023. The region on the negative electrode 20 corresponding to the third end structure 1023 can provide sufficient lithium-ion active insertion sites, while also allowing the positive electrode 10 to have good strength at the third end structure 1023.

[0107] For the even-end a of the positive electrode 10, please refer to Figure 3 A first end structure 1021 is formed on the first coating layer 120, and a second end structure 1022 and a third end structure 1023 are formed on the second coating layer 130. The first end structure 1021, the second end structure 1022 and the third end structure 1023 are all one type of end structure 102. The three together can improve the strength of the positive electrode 10 at the first end 113, and the region on the negative electrode 20 corresponding to the first end 113 can provide sufficient lithium-ion active insertion sites.

[0108] In some embodiments, a fourth end structure 1024 is formed in the region of the first coating layer 120 adjacent to the second end 114. The length of the fourth end structure 1024 is L4, and the thickness of the fourth end structure 1024 is H4. A fifth end structure 1025 is formed in the region of the first coating layer 120 adjacent to the fourth end structure 1024. The length of the fifth end structure 1025 is L5, and the thickness of the fifth end structure 1025 is H5. L4 satisfies the relationship: L4 = 3mm to 10mm. H4 and H satisfy the relationship: H4 - H = -15μm to -1μm. L5 satisfies the relationship: L5 = 10mm to 35mm. H5 and H satisfy the relationship: H5 - H = -6μm to -0μm.

[0109] It should be noted that L4 can be 3mm, 5mm, or 10mm, etc. By setting L4 between 3mm and 10mm, the length of the fourth end structure 1024 can be reasonably planned. H4-H can be -15μm, -10μm, etc. Understandably, when L4 is larger, H4-H can be smaller. For example, when L4 is 10mm, H4-H can be -15μm. This allows for a reasonable balance between the length and thickness of the fourth end structure 1024. The region on the negative electrode 20 corresponding to this fourth end structure can provide sufficient lithium-ion active insertion sites, while also ensuring good strength of the positive electrode at this fourth end structure 1024. L5 can be 10mm, 20mm, or 35mm, etc. By setting L5 between 10mm and 35mm, the length of the fifth end structure 1025 can be reasonably planned. H5-H can be -6μm, -2μm, etc. It is understandable that when L5 is large, H5-H can be small. For example, when L5 is 35mm, H5-H can be -6μm. This can reasonably balance the length and thickness of the fifth end structure 1025. The region on the negative electrode 20 corresponding to the fifth end structure 1025 can provide sufficient lithium-ion active insertion sites, while also allowing the positive electrode 10 to have good strength at the fifth end structure 1025.

[0110] In some embodiments, a sixth end structure 1026 is formed in the region of the second coating layer 130 adjacent to the second end 114. The length of the sixth end structure 1026 is L6, and the thickness of the sixth end structure is H6. L6 satisfies the relationship: L6 = 0 mm ~ 7 mm. H6 and H satisfy the relationship: H6 - H = -15 μm ~ 0 μm.

[0111] It should be noted that the value of L6 must be at least greater than 0. For example, it can be 1 mm, 3 mm, 7 mm, etc. By setting L6 between 0 mm and 7 mm, the length of the sixth end structure 1026 can be reasonably planned. H6-H can be -15 μm, -10 μm, etc. Understandably, when the value of L6 is large, H6-H can be small. For example, when L6 is 7 mm, H6-H can be -15 μm. This can reasonably balance the length and thickness of the sixth end structure 1026. The region on the negative electrode 20 corresponding to the sixth end structure 1026 can provide sufficient lithium-ion active insertion sites, while also ensuring that the positive electrode 10 has good strength at the sixth end structure 1026.

[0112] For the non-near end e of the positive electrode 10, please refer to Figure 3A fourth end structure 1024 and a fifth end structure 1025 are formed on the first coating layer 120, and a sixth end structure 1026 is formed on the second coating layer 130. The fourth end structure 1024, the fifth end structure 1025 and the sixth end structure 1026 are all one of the end structures 102. The three together can enhance the strength of the positive electrode 10 at the second end 114. The region on the negative electrode 20 corresponding to the second end 114 can provide sufficient lithium-ion active insertion sites.

[0113] It is understood that the first end structure 1021 to the sixth end structure 1026 can be selectively arranged on the positive electrode 10. For example, the first end structure 1021, the second end structure 1022, the fourth end structure 1024, and the sixth end structure 1026 can be arranged. In some specific embodiments, the first end structure 1021 to the sixth end structure 1026 can all be arranged on the positive electrode 10. In this case, from the length direction of the positive electrode 10, the first coating layer 120 is provided with three end structures 102, and the second coating layer 130 is also provided with three end structures 102. From the diagonal direction of the positive electrode 10, three end structures 102 are also provided in both diagonal directions of the positive electrode 10. Through this staggered arrangement of the number and position of the end structures 102, the strength of the positive electrode 10 can be effectively improved, and the uniformity of lithium ion release from the first end 113 and the second end 114 of the positive electrode 10 can be maintained.

[0114] The above embodiments mainly design the length and thickness of the end structure 102 in the length direction of the positive electrode 10. In other embodiments, it can be understood that the end structure 102 in the width direction of the positive electrode 10 can also be designed. This part of the end structure 102 can be set according to factors such as the arrangement of the tabs and the width of the positive electrode 10.

[0115] In the embodiments of this application, the first coating layer 120 and the second coating layer 130 can adopt a double-layer structure, and different materials can be used in the double-layer structure, thereby increasing the capacity of the core structure.

[0116] In some embodiments, please refer to Figure 3 The first coating layer 120 includes a first layer 121 and a second layer 122, and the second coating layer 130 includes a third layer 131 and a fourth layer 132. At the first end 113, the first layer 121 and the second layer 122 are flush, and the third layer 131 and the fourth layer 132 are flush. At the second end 114, the first layer 121 and the second layer 122 form a tip f with gradually decreasing thickness, and the third layer 131 and the fourth layer 132 form a tip f with gradually decreasing thickness. Of course, the tip f can also be a whole with decreasing thickness.

[0117] As described above, the flush end a is formed by die-cutting the positive electrode 10, while the tip f is formed by the natural flow and curing of the adhesive. At this tip f, the thickness of the positive electrode 10 gradually decreases. Combined with the aforementioned fourth end structure 1024, fifth end structure 1025, and sixth end structure 1026, the lithium plating efficiency of the positive electrode 10 at this tip f can be guaranteed.

[0118] In some embodiments, the first layer 121 and the third layer 131 are made of a first material, and the second layer 122 and the fourth layer 132 are made of a second material. The first material and the second material are selected from at least one of lithium cobalt oxide, lithium iron phosphate, ternary lithium, and lithium carbonate.

[0119] As an example, the first layer 121 and the third layer 131 can be made of lithium iron phosphate, and the second layer 122 and the fourth layer 132 can be made of lithium carbonate. By combining different materials, the capacity can be increased and the long-cycle performance of the core structure can be improved.

[0120] At the tip f, different combination structures can be formed between the first layer 121 and the second layer 122, and between the third layer 131 and the fourth layer 132. These will be discussed below. Figures 4 to 6 For ease of description, the following embodiments will mainly use the combination structure between the first layer 121 and the second layer 122 as an example. The third layer 131 and the fourth layer 132 can be designed with reference to the first layer 121 and the second layer 122.

[0121] Figure 4 A schematic diagram of a combined structure of a first layer and a second layer according to an embodiment of this application is shown; Figure 5 A schematic diagram of another combined structure of the first layer and the second layer provided according to an embodiment of this application is shown; Figure 6 A schematic diagram of another combination structure of the first layer and the second layer provided according to an embodiment of this application is shown.

[0122] In some embodiments, please refer to Figure 4 The first layer 121 covers the second layer 122. In this embodiment, with the first layer 121 and the second layer 122 having the same thickness, the first layer 121 has more material, and uniform lithium plating can be achieved by reasonably configuring the material selection.

[0123] In some embodiments, please refer to Figure 5 The first layer 121 and the second layer 122 are flush. In this embodiment, with the first layer 121 and the second layer 122 having the same thickness, the first layer 121 and the second layer 122 use the same material, which can form a better end structure 102 of the positive electrode 10.

[0124] In some embodiments, please refer to Figure 6 The second layer 122 extends out of the first layer 121 and the extension length is L7. In this embodiment, by reasonably controlling the size of L7, for example, setting L7 to L7≤2mm, on the one hand, the stability of the positive electrode 10 along the length direction can be guaranteed, and the consistency of capacity can be ensured. On the other hand, it is beneficial to control the thickness of the end structure 102, thereby ensuring the performance of the positive electrode 10.

[0125] Similarly, at the tip f, the fourth layer 132 covers the third layer 131, or the fourth layer 132 is flush with the third layer 131, or the fourth layer 132 extends beyond the third layer 131 and the extension length is L8 (not shown in the figure), where L8 satisfies the relationship: L8≤2mm.

[0126] In a wound core structure, tabs are typically positioned along the width of the core. In a multi-layered wound core structure, each layer has one tab, and the tabs of each layer are stacked along the thickness of the core. The location of the tabs can easily cause a short circuit, for example, the tab may short-circuit to an adjacent electrode. Furthermore, after the positive electrode 10 is die-cut, burrs may be present at the cut edge of the positive current collector 110. After the wound core structure is formed, these burrs pose a risk of puncturing the separator 30, leading to a short circuit or thermal runaway, thus affecting the safety performance of the wound core structure. Therefore, the end of the positive electrode 10 corresponding to the location for forming or connecting the tabs, i.e., along the width direction, needs to be sufficiently clean. It is necessary to ensure that after the positive electrode 10 is die-cut, there may be a small number of burrs at the cut edge, or no burrs at all. Based on this, the positive electrode 10 in this embodiment can also have an insulating layer 300 at one end along its width direction. This insulating layer 300 can wrap around the positive current collector 110, preventing burrs from forming during the die-cutting process.

[0127] Figure 7 A cross-sectional view along the width direction of a positive electrode sheet provided according to an embodiment of this application is shown; Figure 8 A cross-sectional view along the width direction of the first coating layer of a positive electrode sheet according to an embodiment of this application is shown. In some embodiments, please refer to... Figure 7 The positive electrode 10 also includes an insulating layer 300, which is disposed at one end of the positive current collector 110 in the width direction and wraps around the outer periphery of the positive current collector 110. When the positive electrode 10 is die-cut, the insulating layer 300 can protect the positive current collector 110 and prevent burrs from being generated at the cut of the positive current collector 110.

[0128] Based on the setting of insulating layer 300, the present application embodiment designs the structure of insulating layer 300. The main design idea is to embed insulating layer 300 into first coating layer 120 and second coating layer 130. In other words, first coating layer 120 and second coating layer 130 can cover insulating layer 300. First coating layer 120 and second coating layer 130 can release lithium ions normally. Thus, the capacity of the core structure can be achieved without affecting the setting of insulating layer 300.

[0129] In the embodiments of this application, please refer to Figure 7 and Figure 8 The insulating layer 300 covers the outer periphery of the positive current collector 110 and is covered by the first coating layer 120 and / or the second coating layer 130.

[0130] The term "coverage" here means that there is an overlap between the first coating layer 120, the second coating layer 130 and the insulating layer 300, and the insulating layer 300 is covered by the first coating layer 120 and the second coating layer 130.

[0131] To simplify the description and facilitate understanding, the following embodiments will mainly use the structural design of the first coating layer 120 and the insulating layer 300 as an example for illustration.

[0132] In the first type of embodiment, the first layer 121 and the second layer 122 both cover the insulating layer 300, and the third layer 131 and the fourth layer 132 both cover the insulating layer 300.

[0133] In this first type of embodiment, the first layer 121 and the second layer 122 are both covered by the insulating layer 300, which can simplify the surface structure of the positive electrode 10. During coating, two molds can be used to coat the electrode separately. One mold is used to form the insulating layer 300, and the other mold can be used to form the first layer 121 and the second layer 122, thus simplifying the coating process.

[0134] In some embodiments, please refer to Figure 8 An overlapping region 310 is formed on the insulating layer 300, which overlaps with the first layer 121 and the second layer 122. The length of the overlapping region 310 is W1, which satisfies the relationship: W1 = 10 μm ~ 500 μm.

[0135] It is understandable that the overlapping region 310 is the bonding location between the first coating layer 120 and the insulating layer 300. The size of this overlapping region 310 can indicate the strength of the bonding force. When the size of W1 is larger, the bonding force is larger, and the connection strength between the first coating layer 120 and the insulating layer 300 is higher. The insulating layer 300 can effectively connect the positive current collector 110 and the first coating layer 120, preventing the first coating layer 120 from falling off. When the size of W2 is smaller, the bonding force is smaller, but the first coating layer 120 can release more lithium ions, which can ensure the capacity of the core structure. Designing W1 according to the above dimensions, for example, setting W1 to 10μm, 250μm, or 500μm, can improve the bonding force without sacrificing capacity.

[0136] On the other hand, due to the flow and curing of the adhesive during the coating process, the insulating layer 300 will also form a tip f at the end near the first coating layer 120, so that the thickness of the insulating layer 300 gradually increases in the direction away from the first coating layer 120. Therefore, the larger the size of W1 is designed, the more likely it is to cause capacity loss. Designing W1 to be in the range of 10μm to 500μm can avoid capacity loss. In this range, the first coating layer 120 and the insulating layer 300 are basically in contact by the tip f, which will not affect or will have little effect on the release of lithium ions from the first coating layer 120.

[0137] In some embodiments, please refer to Figure 8 The overlapping region 310 includes a first overlapping region 311 formed by the first layer 121 and the insulating layer 300 and a second overlapping region 312 formed by the second layer 122 and the insulating layer 300. The length of the first overlapping region 311 is W2 and the length of the second overlapping region 312 is W3. W1, W2 and W3 satisfy the following relationship: W = W1 + W2, W3 / W1 = 0 ~ 0.75, W2 = 10 μm ~ 500 μm, W3 = 0 μm ~ 250 μm.

[0138] This section primarily focuses on the design of the dimensions of the first overlapping region 311 and the second overlapping region 312. As can be seen from the above design, the second overlapping region 312 can be designed to be relatively short. This is based on the consideration of maximizing the overlap between the first coating layer 120 and the insulating layer 300 through the tip f. Designing W1, W2, and W3 according to the above relationship can effectively improve the bonding strength while avoiding affecting the capacity.

[0139] As an example, W1 can be 500 μm, W2 can be 300 μm, and W3 can be 200 μm. This combination of lengths ensures sufficient connection strength between the insulating layer 300 and the first coating layer 120, while also avoiding a reduction in capacity.

[0140] In other examples, the combination of W1, W2 and W3 can be varied. By properly configuring the dimensions of W1, W2 and W3, it can be ensured that lithium plating will not occur at the end of the core structure corresponding to the positive electrode 10 where the insulating layer 300 is provided.

[0141] In some embodiments, please refer to Figure 7 and Figure 8 The length of the insulating layer 300 is W20, and a non-overlapping region 320 is formed on the insulating layer 300. The length of the non-overlapping region 320 is W4. W20, W4 and W1 satisfy the relationship: W20=W1+W4, W4=500μm~2990μm.

[0142] This section mainly focuses on the design relationship between the total length of the insulation layer 300 and the length of the overlapping region 310. As can be seen from the above design, the length of the non-overlapping region 320 is designed to be relatively long. This design is based on die-cutting, and W4 is designed to the above dimensions. For example, W4 can be 500μm, 1000μm, or 29905μm, etc. This ensures the length of the non-overlapping region 320, which facilitates better protection of the positive current collector 110 during die-cutting, reduces the generation of burrs on the positive current collector 110 during die-cutting, and thus improves the safety performance of the core structure.

[0143] On the other hand, designing the non-overlapping region 320 to be longer also helps to protect the positive electrode tab. After the positive electrode tab is connected to the positive current collector 110, the non-overlapping region 320 can prevent the positive electrode tab from bending or other phenomena during subsequent processing, which can avoid short circuits between the positive electrode tab and adjacent electrode sheets and also improve the safety performance of the core structure.

[0144] In some embodiments, W1 and W20 satisfy the relationship: W1 / W20 = 1 / 300 to 1 / 2.

[0145] Therefore, the length ratio of the overlapping area 310 to the insulating layer 300 can be balanced. Designing according to the above dimensions can improve the connection strength between the first coating layer 120 and the insulating layer 300, and can also avoid capacity loss during die cutting.

[0146] The above description is for the position on the positive electrode plate 10 where a positive electrode tab needs to be set. When there is no need to set a tab on the positive electrode plate 10, the insulating layer 300 can be designed with other dimensions.

[0147] For example, in some embodiments, please refer to Figure 8A non-tab region is formed on the positive current collector 110. In the non-tab region, the length of the insulating layer 300 is W30, and the length of the non-overlapping region 320 is W5. W30, W4 and W1 satisfy the following relationship: W30=W1+W5, W5=100μm~1000μm.

[0148] The non-tab region is the location on the positive electrode sheet 10 where a positive electrode tab is not required. In this non-tab region, the length W5 of the insulating layer 300 can be designed to be smaller than the aforementioned W4. For example, W5 can be designed to be 100μm, 500μm, or 1000μm. W4 is designed according to the above dimensions. On the one hand, it can save material of the insulating layer 300 and simplify the coating process. On the other hand, when the positive electrode sheet 10 is die-cut, the die-cutting action can be made to occur on the insulating layer 300. Without damaging the first coating layer 120, the dimension of the positive electrode sheet 10 in the width direction can be made as short as possible, reducing the proportion occupied by the insulating layer 300, thereby improving the energy density of the core structure.

[0149] In some embodiments, W4 and W5 satisfy the relationship: W5 / W4 = 0.2 to 0.8.

[0150] Understandably, the values ​​of W5 / W4 can be set according to actual needs. Setting W5 / W4 within the above range ensures that when the positive electrode sheet 10 is die-cut, the tab area and the non-tab area can form a good transition during die-cutting. This ensures that the junction between cutting along the length direction of the positive electrode sheet 10 and cutting along the width direction of the positive electrode sheet 10 is still within the area of ​​the insulating layer 300, which can better protect the positive current collector 110 at that location and prevent burrs from forming on the positive current collector 110 due to the long dwell time of the die-cutting action, thereby ensuring the safety performance of the core structure.

[0151] In some embodiments, please refer to Figure 7 The misalignment distance between the first layer 121 and the third layer 131 is W6, which satisfies the relationship: W6 = 0 μm ~ 500 μm. The misalignment distance between the second layer 122 and the fourth layer 132 is W7, which satisfies the relationship: W7 = 0 μm ~ 990 μm. The insulating layer 300 includes a first insulating layer 330 connected to the first connecting surface 111 and a second insulating layer 340 connected to the second connecting surface 112. The misalignment distance between the first insulating layer 330 and the second insulating layer 340 is W8, which satisfies the relationship: 0 μm ~ 990 μm.

[0152] This section mainly focuses on controlling the misalignment that may occur during the coating process. By designing W6, W7, and W8 according to the above dimensions, it can provide guidance for the coating process. Based on meeting the above dimensions, the number of lithium ions that can be released on both sides of the positive electrode current collector 110 is basically the same, which can ensure the consistency of the core structure and avoid lithium plating on one side of the positive electrode current collector 110 due to uneven lithium ion release.

[0153] As an example, when higher precision is required, W6 can be set to 100μm, W7 can be set to 100μm, and W8 can be set to 100μm. As another example, when lower precision is required, W6 can be set to 400μm, W7 can be set to 400μm, and W8 can be set to 500μm.

[0154] The above embodiments illustrate the case where both the first layer 121 and the second layer 122 cover the insulating layer 300. In these embodiments, it can be understood that the design details regarding length can be varied as needed. The length dimensions described above represent the dimensions of the corresponding features along the width direction of the positive electrode sheet 10.

[0155] In the second type of embodiment, the insulating layer 300 covers the first layer 121, the second layer 122 covers the insulating layer 300, the insulating layer 300 covers the fourth layer 132, and the third layer 131 covers the insulating layer 300.

[0156] In this second type of embodiment, the insulating layer 300, the first layer 121 and the second layer 122 form a structure that combines in pairs, that is, the first layer 121 is combined with the insulating layer 300, and the insulating layer 300 is combined with the second layer 122. This arrangement can improve the connection strength between the first layer 121, the insulating layer 300 and the second layer 122, and can also better ensure the capacity of the core structure.

[0157] Figure 9 Another cross-sectional view along the width direction of a positive electrode sheet provided according to an embodiment of this application is shown; Figure 10 Another cross-sectional view along the width direction of the first coating layer of a positive electrode sheet provided according to an embodiment of this application is shown. Please refer to... Figure 9 and Figure 10As mentioned above, the thickness of the insulating layer 300 gradually increases in the direction away from the first coating layer 120. When the insulating layer 300 is configured to be bonded between the first layer 121 and the second layer 122, during coating, the second layer 122 can be completely coated first, then the insulating layer 300 can be coated, and then the first layer 121 can be coated. This structure and coating method can expose the end of the second layer 122, so that the second layer 122 is not affected by the insulating layer 300. The second layer 122 can release lithium ions normally, thereby ensuring the capacity of the core structure.

[0158] In some embodiments, please refer to Figure 10 An overlapping region 310 is formed on the insulating layer 300, which overlaps with the first layer 121 and the second layer 122. The length of the overlapping region 310 is W9, which satisfies the relationship: W9 = 20μm ~ 500μm.

[0159] The overlapping region 310 here can be understood based on the insulating layer 300. That is, the portion of the insulating layer 300 bonded between the first layer 121 and the second layer 122 forms the overlapping region 310. The size of this overlapping region 310 can represent the strength of the bonding force. When the size of W9 is larger, the bonding force is larger, and the connection strength between the first coating layer 120 and the insulating layer 300 is higher. The insulating layer 300 can effectively connect the positive current collector 110 and the first coating layer 120, preventing the first coating layer 120 from falling off. When the size of W9 is smaller, the bonding force is smaller, but the first coating layer 120 can release more lithium ions, which can ensure the capacity of the core structure. Designing W9 according to the above dimensions, for example, setting W9 to 20μm, 250μm, or 500μm, can improve the bonding force without sacrificing capacity.

[0160] On the other hand, due to the flow and curing of the adhesive during the coating process, the insulating layer 300 will also form a tip f at the end near the first coating layer 120, so that the thickness of the insulating layer 300 gradually increases in the direction away from the first coating layer 120. Therefore, the larger the size of W9 is designed, the more likely it is to cause capacity loss. Designing W9 to be in the range of 20μm to 500μm can avoid capacity loss. In this range, the first coating layer 120 and the insulating layer 300 are basically in contact by the tip f, which will not affect or will have little effect on the release of lithium ions from the first coating layer 120.

[0161] In some embodiments, please refer to Figure 10 The overlapping region 310 includes a third overlapping region 313 formed by the second layer 122 and the insulating layer 300. The length of the third overlapping region 313 is W10, and W9 and W10 satisfy the following relationship: W10 / W9 = 0.08 to 0.75, W10 = 0 μm to 250 μm.

[0162] The length and proportion of the third overlapping region 313 are designed here. It can be understood that a larger value for W10 indicates that during coating, the contact position between the insulating layer 300 and the second layer 122 is closer to the middle structure 101 of the positive electrode 10. In this case, the thickness of the first coating layer at the end structure 102 of the positive electrode 10 is closer to the thickness of the first coating layer at the middle structure 101. This allows for control over the thickness of the end portion of the first coating layer 120 of the positive electrode 10 along its width. When the thickness difference is smaller, the positive electrode 10 adheres more tightly to the separator 30 and the negative electrode 20, thereby reducing the internal resistance to lithium-ion migration, improving the smoothness of lithium-ion migration, and preventing lithium plating. However, the value of W10 should not be too large; otherwise, lithium ions in the bottom region of the second layer 122 will have difficulty migrating, easily causing capacity loss.

[0163] As an example, W10 can be 100 μm and W9 can be 900 μm. This size relationship can prevent lithium plating while ensuring capacity.

[0164] In some embodiments, please refer to Figure 9 The misalignment distance between the second layer 122 and the fourth layer 132 is W11, and W11 satisfies the relationship: W11 = 0 μm ~ 980 μm. The insulating layer 300 includes a first insulating layer 330 connected to the first connecting surface 111 and a second insulating layer 340 connected to the second connecting surface 112. The misalignment distance between the first insulating layer 330 and the second insulating layer 340 is W12, and W12 satisfies the relationship: 0 μm ~ 980 μm.

[0165] This section mainly focuses on controlling the misalignment that may occur during the coating process. By designing W11 and W12 according to the above dimensions, guidance can be provided for the coating process. Based on meeting the above dimensions, the number of lithium ions that can be released on both sides of the positive electrode current collector 110 is basically the same, which can ensure the consistency of the core structure and avoid lithium plating on one side of the positive electrode current collector 110 due to uneven lithium ion release.

[0166] As an example, when higher precision is required, W11 can be set to 100μm and W12 can be set to 100μm. As another example, when lower precision is required, W11 can be set to 900μm and W12 can be set to 900μm.

[0167] The above embodiments illustrate the case where the first layer 121 covers the insulating layer 300, and the insulating layer 300 covers the second layer 122. In these embodiments, it can be understood that the design details regarding length can be varied as needed. The length dimensions described above represent the dimensions of the corresponding features along the width direction of the positive electrode sheet 10.

[0168] The above embodiments provide a detailed description of the structure and process of the positive electrode 10. In the above description, it should be further noted that the positive electrode 10 is mainly described from the length and width directions. For example, a first end 113 and a second end 114 are formed in the length direction of the positive electrode 10, and then the end structures 102 are described in detail based on the first end 113 and the second end 114. For another example, a positive electrode tab can be connected to one end in the width direction of the positive electrode 10, and the positive current collector 110 forms a tab region and a non-tab region at this end. The design of the insulating layer 300 is described in detail based on this end.

[0169] In the above embodiments, the design of each end structure 102 can avoid the occurrence of lithium plating, and the design of the insulating layer 300 can prevent the occurrence of lithium plating while protecting the positive electrode 10.

[0170] In addition to the embodiments listed above, the negative electrode 20 in the embodiments of this application may also adopt related designs. The following embodiments will describe the negative electrode 20 in detail.

[0171] Figure 11 A cross-sectional view along the length of a negative electrode sheet according to an embodiment of this application is shown. In some embodiments, please refer to... Figure 3 The negative electrode 20 includes a negative electrode body 200, which includes a negative electrode current collector 210, a third coating layer 220, and a fourth coating layer 230. The third coating layer 220 and the fourth coating layer 230 belong to the category of active material embedding layers.

[0172] The negative electrode current collector 210 needs to be in contact with the third coating layer 220 and the fourth coating layer 230 to achieve the function of collecting current. The negative electrode current collector 210 specifically has a third connecting surface 211 and a fourth connecting surface 212. The third coating layer 220 is formed on the third connecting surface 211 of the negative electrode current collector 210, and the fourth coating layer 230 is formed on the fourth connecting surface 212 of the negative electrode current collector 210.

[0173] The third coating layer 220 can be formed on the negative electrode current collector 210 by coating, and the fourth coating layer 230 can be formed on the negative electrode current collector 210 by coating.

[0174] Along the length of the negative electrode current collector 210, the negative electrode current collector 210 has a third end 213 and a fourth end 214. The negative electrode current collector 210, the third coating layer 220 and the fourth coating layer 230 are flush at the third end 213 to form a flush end a, and the negative electrode current collector 210, the third coating layer 220 and the fourth coating layer 230 are not flush at the fourth end 214 to form a non-flush end e.

[0175] Unlike the aforementioned positive electrode 10, the negative electrode 20 can be formed during production without a die-cutting process, simply by coating and rolling. Both the flush end a and the non-flush end e have sharp points f formed by the flow and curing of the adhesive. Of course, in other embodiments, the negative electrode 20 can also be formed without sharp points by cutting, for example, by laser cutting to remove the sharp points f.

[0176] In some embodiments, please refer to Figure 11 A first region g and a second region h are formed on the third coating layer 220 and the fourth coating layer 230. The distance between the first region g and the third end 213 or the fourth end 214 is S1, and the thickness of the first region g is V1. The distance between the second region h and the third end 213 or the fourth end 214 is S2, and the thickness of the second region h is V2. S1, S2, V1 and V2 satisfy the following relationship: S1≥50mm, V1=35μm~70μm, S2=3mm~50mm, V2-V1=-3μm~7μm.

[0177] In this embodiment, the thickness design of the negative electrode 20 is similar to that of the positive electrode 10, but the thickness design of the negative electrode 20 is basically the opposite of that of the positive electrode 10. That is, for the negative electrode 20, the thickness of the edge of the negative electrode 20 can be greater than the thickness of the middle region of the negative electrode 20. This is of great significance for ensuring the smooth migration of lithium ions and preventing lithium plating.

[0178] Specifically, as described above, in the second embodiment of the aforementioned insulating layer 300, the value of W10 can be as large as possible. This is because it allows control over the thickness of the end portion of the first coating layer 120 along its width, ensuring the positive electrode 10 adheres tightly to the negative electrode 20, thereby facilitating the smooth migration of lithium ions. In other embodiments described above, the positive electrode 10 has an end structure 102 along its length. The thickness of the first coating layer of this end structure 102 is smaller than the thickness of the first coating layer of the middle structure 101 of the positive electrode 10. To compensate for this size design, the thickness of the edge region of the negative electrode 20 along its length can be designed to be thicker than that of the middle region. This still allows the negative electrode 20 to adhere tightly to the positive electrode 10, ensuring the smooth migration of lithium ions while achieving the respective functions of the positive electrode 10 and the negative electrode 20. It also makes it easier for lithium ions to embed into the negative electrode 20.

[0179] As an example, when H1-H = -15μm, V2 can take the value of 15μm or greater than 15μm, and when H3-H = -15μm, V1 can take the value of 15μm or greater than 15μm.

[0180] It is understandable that S1, S2, V1 and V2 are designed according to the above dimensions, which basically correspond to the first end structure 1021 and the third end structure 1023 on the positive electrode 10, and can ensure the stability and consistency of the core structure in terms of performance.

[0181] Of course, for the negative electrode 20, the first region g and the second region h are only examples. In other embodiments, more regions can be formed on the third coating layer 220 and the fourth coating layer 230. For example, multiple regions can be set according to the end structures 102 of the positive electrode 10.

[0182] The third coating layer 220 and the fourth coating layer 230 in the embodiments of this application can adopt a double-layer structure, and different materials can be used in the double-layer structure, thereby increasing the capacity of the core structure.

[0183] In some embodiments, please refer to Figure 11 The third coating layer 220 includes a fifth layer 221 and a sixth layer 222, and the fourth coating layer 230 includes a seventh layer 231 and an eighth layer 232. At the third end 213, the fifth layer 221 and the sixth layer 222 form a tip f with gradually decreasing thickness, and the seventh layer 231 and the eighth layer 232 form a tip f with gradually decreasing thickness. At the fourth end 214, the fifth layer 221 and the sixth layer 222 form a tip f with gradually decreasing thickness, and the seventh layer 231 and the eighth layer 232 form a tip f with gradually decreasing thickness.

[0184] In some embodiments, the fifth layer 221 and the seventh layer 231 are made of a third material, and the sixth layer 222 and the eighth layer 232 are made of a fourth material, wherein the third material and the fourth material are selected from at least one of graphite, silicon carbide, silicon oxide, and pure silicon.

[0185] As an example, the fifth layer 221 and the seventh layer 231 can be made of graphite, and the sixth layer 222 and the eighth layer 232 can be made of silicon carbide. By combining different materials, the energy density can be increased, and the fast charging performance of the core structure can also be improved.

[0186] On the other hand, by using silicon as the material, the negative electrode 20 can accommodate more active sites for lithium ions, which can reduce the thickness of the third coating layer 220 and the fourth coating layer 230, and further increase the volumetric energy density of the core structure.

[0187] At the tip f, different combination structures can be formed between the fifth layer 221 and the sixth layer 222, and between the seventh layer 231 and the eighth layer 232. These combinations can be set with reference to the positive electrode 10. For example, at the tip f, the fifth layer 221 covers the sixth layer 222, or the fifth layer 221 is flush with the sixth layer 222, or the sixth layer 222 extends out of the fifth layer 221 and the extension length is S3 (not shown in the figure), where S3 satisfies the relationship: S3≤2mm.

[0188] Similar to the positive tab described above, the negative electrode 20 also has a tab region, which is used to connect the negative electrode tab. The position of the negative electrode 20 corresponding to the tab region can be designed accordingly.

[0189] Figure 12 A cross-sectional view along the width direction of a negative electrode sheet provided according to an embodiment of this application is shown; Figure 13 A cross-sectional view along the width direction of another negative electrode sheet provided according to an embodiment of this application is shown. Please refer to... Figure 12 and Figure 13 Along the width direction of the negative electrode current collector 210, the negative electrode current collector 210 has a fifth end 215 and a sixth end 216. At the fifth end 215, the fifth layer 221 and the sixth layer 222 form a tip f with gradually decreasing thickness, and the seventh layer 231 and the eighth layer 232 form a tip f with gradually decreasing thickness, or the fifth layer 221 is flush with the sixth layer 222, and the seventh layer 231 is flush with the eighth layer 232.

[0190] Please refer to Figure 12 In the tab region of the negative electrode 20, at the fifth end 215, the fifth layer 221 and the sixth layer 222 form a tip f with gradually decreasing thickness, and the seventh layer 231 and the eighth layer 232 form a tip f with gradually decreasing thickness. In order to ensure the edge thickness of the negative electrode 20 at the fifth end 215, increase the lithium-ion active insertion sites of the negative electrode 20 and prevent lithium plating, the third coating layer 220 formed by the fifth layer 221 and the sixth layer 222 can cover the fourth coating layer 230 formed by the seventh layer 231 and the eighth layer 232. The misalignment distance between the third coating layer 220 and the fourth coating layer 230 can be as small as possible, for example, controlled within 2 mm.

[0191] Please refer to Figure 13 The negative electrode 20 can be made free of sharp points (f) by laser cutting. Specifically, this can be achieved through a process of applying adhesive, coating, and peeling off the adhesive, or through the aforementioned process of coating, rolling, and then laser cutting. Figure 13In the example shown, it can be ensured that there is no misalignment between the third coating layer 220 and the fourth coating layer 230, that the negative electrode 20 has sufficient lithium-ion active insertion sites, and that the negative electrode 20 can better adhere to the separator 30 and the positive electrode 10, which is beneficial to the transport of lithium ions and can avoid lithium plating.

[0192] The above design also applies to the sixth terminal 216, and will not be elaborated further.

[0193] The above embodiments provide a detailed description of the structure and process of the negative electrode 20. In the above description, it should be further noted that the negative electrode 20 is mainly described from the length and width directions. For example, a third end 213 and a fourth end 214 are formed in the length direction of the negative electrode 20, and the edge thickness of the negative electrode 20 is described in detail based on the third end 213 and the fourth end 214. As another example, the fifth end 215 in the width direction of the negative electrode 20 can be connected to the negative electrode tab, and the negative electrode current collector 210 forms a tab region at this end. The tip f of the negative electrode 20 and the case excluding the tip f are described based on the fifth end 215.

[0194] The core structure in this application embodiment can be applied to various electrical devices, including passenger cars, commercial vehicles, electric bicycles, heavy trucks, energy storage facilities, battery swapping stations, engineering manufacturing equipment, and intelligent devices.

[0195] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are 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, and therefore should not be construed as a limitation of this application.

[0196] In the description of this application, it should be understood that the terms "comprising" and "having" and any variations thereof used in the embodiments of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0197] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the connection within two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0198] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A positive electrode plate, characterized in that, include: A positive electrode body, the positive electrode body comprising an intermediate structure and an end structure; The positive electrode body includes: A positive electrode current collector has a first connecting surface and a second connecting surface, as well as a first end and a second end along the length direction of the positive electrode current collector. A first coating layer is formed on the first connection surface of the positive electrode current collector; And a second coating layer, formed on the second connection surface of the positive electrode current collector, The first coating layer includes a first layer and a second layer, and the second coating layer includes a third layer and a fourth layer. Wherein, the first coating layer of the intermediate structure has a first thickness, the first coating layer of the end structure has a second thickness, and the second thickness of the first coating layer of the end structure is less than the first thickness of the first coating layer of the intermediate structure; The positive electrode sheet further includes an insulating layer disposed at one end of the positive electrode current collector in the width direction, and the insulating layer is covered by the first coating layer and / or the second coating layer.

2. The positive electrode sheet according to claim 1, characterized in that, A first end structure is formed on the first coating layer near the first end. The length of the first end structure is L1, and the thickness of the first end structure is H1. The thickness of the first coating layer of the intermediate structure is H. H1 and H satisfy the relationship: H1-H=-15μm~0μm; and / or, A second end structure is formed in the region adjacent to the first end on the second coating layer. The length of the second end structure is L2, and the thickness of the second end structure is H2. A third end structure is formed in the region adjacent to the second end structure on the second coating layer. The length of the third end structure is L3, and the thickness of the third end structure is H3. H2 and H satisfy the relationship: H2-H = -15μm to -1μm, and / or H3 and H satisfy the relationship: H3-H = -15μm to -1μm.

3. The positive electrode sheet according to claim 2, characterized in that, A fourth end structure is formed on the first coating layer adjacent to the second end, the fourth end structure having a length of L4 and a thickness of H4. A fifth end structure is formed on the first coating layer adjacent to the fourth end structure, the fifth end structure having a length of L5 and a thickness of H5. H4 and H satisfy the relationship: H4-H = -15μm to -1μm, and / or H5 and H satisfy the relationship: H5-H = -6μm to -0μm; and / or, A sixth end structure is formed in the region adjacent to the second end on the second coating layer. The length of the sixth end structure is L6 and the thickness of the sixth end structure is H6. H6 and H satisfy the relationship H6-H=-15μm~0μm.

4. The positive electrode sheet according to claim 1, characterized in that, At the first end, the first and second layers are flush, and / or the third and fourth layers are flush; at the second end, the first and second layers are pointed, and / or the third and fourth layers are pointed.

5. The positive electrode sheet according to claim 4, characterized in that, At the tip, the first layer covers the second layer, or the first layer is flush with the second layer, or the second layer extends beyond the first layer by a length L7, where L7 satisfies the relationship: L7≤2mm. And / or, at the tip, the fourth layer covers the third layer, or the fourth layer is flush with the third layer, or the fourth layer extends beyond the third layer by a length of L8, where L8 satisfies the relationship: L8≤2mm.

6. The positive electrode sheet according to claim 1, characterized in that, The first and second layers both cover the insulating layer, and the third and fourth layers both cover the insulating layer.

7. The positive electrode sheet according to claim 6, characterized in that, An overlapping region is formed on the insulating layer that overlaps with the first layer and the second layer. The length of the overlapping region is W1. The overlapping region includes a first overlapping region formed by the first layer and the insulating layer and a second overlapping region formed by the second layer and the insulating layer. The length of the first overlapping region is W2, and the length of the second overlapping region is W3. W1, W2, and W3 satisfy the following relationship: W1 = W2 + W3, and / or W3 / W1 = 0 to 0.

75.

8. The positive electrode sheet according to claim 7, characterized in that, The length of the insulating layer is W20, and a non-overlapping region is formed on the insulating layer. The length of the non-overlapping region is W4, and W1 and W20 satisfy the relationship: W1 / W20 = 1 / 300 to 1 / 2.

9. The positive electrode sheet according to claim 8, characterized in that, A non-tab region is formed on the positive current collector. In the non-tab region, the length of the insulating layer is W30, the length of the non-overlapping region is W5, and W4 and W5 satisfy the relationship: W5 / W4 = 0.2~0.

8.

10. The positive electrode sheet according to claim 1, characterized in that, The insulating layer covers the first layer, the second layer covers the insulating layer, the insulating layer covers the fourth layer, and the third layer covers the insulating layer.

11. The positive electrode sheet according to claim 10, characterized in that, An overlapping region is formed on the insulating layer that overlaps with the first layer and the second layer. The length of the overlapping region is W9. The overlapping region includes a third overlapping region formed by the second layer and the insulating layer. The length of the third overlapping region is W10. W9 and W10 satisfy the relationship: W10 / W9 = 0.08~0.

75.

12. A core structure, characterized in that, include: The positive electrode sheet according to any one of claims 1 to 11; Negative electrode plate; And a separator, wherein the separator is disposed between the positive electrode and the negative electrode.

13. The core structure according to claim 12, characterized in that, The negative electrode includes a negative electrode body, and the negative electrode body includes: The negative electrode current collector has a third connecting surface and a fourth connecting surface, as well as a third end and a fourth end along the length direction of the negative electrode current collector; A third coating layer is formed on the third connection surface of the negative electrode current collector; And a fourth coating layer, formed on the fourth connection surface of the negative electrode current collector. Wherein, the negative electrode current collector, the third coating layer and the fourth coating layer are flush at the third end to form a flush end, and the negative electrode current collector, the third coating layer and the fourth coating layer are not flush at the fourth end to form a non-flush end.

14. The core structure according to claim 13, characterized in that, A first region and a second region are formed on the third coating layer and the fourth coating layer. The distance between the first region and the third end or the fourth end is S1, and the thickness of the first region is V1. The distance between the second region and the third end or the fourth end is S2, and the thickness of the second region is V2. S1, S2, V1 and V2 satisfy the following relationship: S1≥50mm, V2-V1=-3μm~7μm.

15. The core structure according to claim 13, characterized in that, The third coating layer includes a fifth layer and a sixth layer, and the fourth coating layer includes a seventh layer and an eighth layer. At the third end, the fifth layer and the sixth layer form a tip, and the seventh layer and the eighth layer form a tip. At the fourth end, the fifth layer and the sixth layer form a tip, and the seventh layer and the eighth layer form a tip.

16. The core structure according to claim 15, characterized in that, At the tip, the fifth layer covers the sixth layer, or the fifth layer is flush with the sixth layer, or the sixth layer extends beyond the fifth layer by a length of S3, where S3 satisfies the relationship: S3≤2mm.

17. The core structure according to claim 12, characterized in that, Along the winding direction of the core structure, the positive electrode sheet is formed with a flush end, which is located at the innermost side of the core structure and in a straight section.

18. An electrical appliance, characterized in that, Includes the core structure according to any one of claims 12 to 17.

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