Battery cell and battery

Abstract

The embodiment of the utility model provides a battery cell and a battery, and relates to the technical field of batteries. The battery cell comprises a positive plate, a negative plate and a diaphragm positioned between the positive plate and the negative plate, and the positive plate, the negative plate and the diaphragm are laminated and wound to form the battery cell. A plurality of first concave-convex structures which are arranged at intervals are formed on the first region of the positive plate, first convex parts are formed on one side of the first concave-convex structures in the thickness direction of the positive plate, and first concave parts are formed on the other side of the first concave-convex structures in the thickness direction of the positive plate; a plurality of second concave-convex structures which are arranged at intervals are formed on the second region of the negative plate, second convex parts are formed on one side, in the thickness direction of the positive plate, of each second concave-convex structure, and second concave parts are formed on the other side, in the thickness direction of the positive plate, of each second concave-convex structure, so that electrolyte between the electrode plates is sufficient, and the infiltration effect is improved; therefore, the cycle performance of the battery is improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a battery cell and a battery. Background Technology

[0002] With the rapid development of lithium-ion battery technology, people have put forward higher requirements for the energy density, cycle life and safety performance of lithium-ion batteries.

[0003] In related technologies, the cell of a lithium-ion battery is formed by winding a positive electrode, a separator, and a negative electrode. The positive electrode includes a first region, a second region, and a third region connected in sequence. The first region has an active material coating on both sides, the second region has an active material coating on only one side, and the third region has no active material coating on either side.

[0004] However, during the battery manufacturing process, the second region of the positive electrode is located on the outer ring of the cell. During the winding process of the electrode, the second region of the positive electrode is prone to curling or wrinkling due to the winding stress, which can lead to interface problems at the location of the second region and cause safety issues such as lithium plating during battery cycling. Utility Model Content

[0005] This utility model provides a battery cell and battery to solve the safety problems such as lithium plating caused by curling or wrinkling in the second region of the positive electrode of a lithium-ion battery due to winding stress.

[0006] In a first aspect, this utility model provides a battery cell, including a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet, wherein the positive electrode sheet, the negative electrode sheet, and the separator are stacked and wound together to form the battery cell;

[0007] The positive electrode includes a first current collector and a first active material layer located on both sides of the first current collector;

[0008] The positive electrode includes a first region in which the first active material layer is disposed on both sides of the first current collector, and a second region in which the first active material layer is disposed only on one side of the first current collector.

[0009] The second region is located on the side of the first region away from the interior of the battery cell;

[0010] The second region includes the portion corresponding to the outermost ring of the positive electrode sheet;

[0011] The positive electrode sheet has a plurality of spaced-apart first concave-convex structures formed on the first region. The first concave-convex structures form a first protrusion on one side of the thickness direction of the positive electrode sheet and a first concave structure on the other side of the thickness direction of the positive electrode sheet.

[0012] The positive electrode sheet has a plurality of spaced second concave-convex structures formed on the second region. The second concave-convex structures form a second protrusion on one side of the positive electrode sheet in the thickness direction and a second concave structure forms a second recess on the other side of the positive electrode sheet in the thickness direction.

[0013] The distance between two adjacent first protrusions is D1, and the distance between two adjacent second protrusions is D2, wherein D2 > D1.

[0014] In one possible implementation, the ratio of D2 to D1 is greater than 1 and less than or equal to 1.5; and / or,

[0015] The D1 is greater than or equal to 1 mm and less than or equal to 8 mm; and / or,

[0016] The D2 is greater than or equal to 3 mm and less than or equal to 10 mm.

[0017] In one possible implementation, in the thickness direction of the positive electrode sheet, the height of the second protrusion is H2, and the height of the first protrusion is H1, wherein H2 ≤ H1.

[0018] In one possible implementation, the ratio of H2 to H1 is greater than or equal to 1 / 5 and less than or equal to 3 / 5; and / or,

[0019] H1 is greater than or equal to 3 μm and less than or equal to 100 μm; and / or,

[0020] The H2 is greater than or equal to 3 μm and less than or equal to 35 μm.

[0021] In one possible implementation, in the thickness direction of the positive electrode sheet, the area of ​​the projection of the first protrusion is S1, and the area of ​​the projection of the second protrusion is S2, wherein S2 > S1.

[0022] In one possible implementation, the ratio of S2 to S1 is greater than or equal to 1.2 and less than or equal to 3; and / or,

[0023] The S1 is greater than or equal to 0.1 mm 2 and less than or equal to 7mm 2 ; and / or,

[0024] The S2 is greater than or equal to 0.5mm 2and less than or equal to 10mm 2 .

[0025] In one possible implementation, in the winding direction of the positive electrode sheet, the distance between adjacent first protrusions and second protrusions is greater than or equal to 2 mm and less than or equal to 10 mm.

[0026] In one possible implementation, the boundary between the first region and the second region is the first boundary in the winding direction of the positive electrode sheet;

[0027] The distance between the first protrusion and the first boundary is greater than or equal to 1 mm; and / or,

[0028] The distance between the second protrusion and the first boundary is greater than or equal to 1 mm.

[0029] In one possible implementation, in the width direction of the positive electrode sheet, at least one edge of the first region is provided with a first clearance portion, and at least one edge of the second region is provided with a second clearance portion.

[0030] In the thickness direction of the positive electrode sheet, the projection of the first protrusion does not coincide with the projection of the first clearance portion, and the projection of the second protrusion does not coincide with the projection of the second clearance portion.

[0031] In one possible implementation, the positive electrode sheet includes alternating straight regions and arc regions in the winding direction of the positive electrode sheet;

[0032] The first convex portion located in the arc region is an arc region convex portion, and the first convex portion located in the flat region is a flat region convex portion. In the thickness direction of the positive electrode sheet, the height of the arc region convex portion is H3, and the height of the flat region convex portion is H4, wherein H3 > H4.

[0033] In one possible implementation, the ratio of H3 to H4 is greater than 1 and less than or equal to 1.5; and / or,

[0034] The H3 is greater than or equal to 5 μm and less than or equal to 100 μm; and / or,

[0035] The H4 is greater than or equal to 3 μm and less than or equal to 80 μm.

[0036] In one possible implementation, the distance between two adjacent arc-shaped protrusions is D6, and the distance between two adjacent straight protrusions is D7, wherein D6 ≤ D7.

[0037] In one possible implementation, the ratio of D6 to D7 is greater than or equal to 0.5 and less than or equal to 1; and / or,

[0038] The D6 is greater than or equal to 1 mm and less than or equal to 5 mm; and / or,

[0039] The D7 is greater than or equal to 2 mm and less than or equal to 8 mm.

[0040] In one possible implementation, in the thickness direction of the positive electrode sheet, the projected area of ​​the arc-shaped protrusion is S3, and the projected area of ​​the flat protrusion is S4, wherein S3 ≤ S4.

[0041] In one possible implementation, the ratio of S3 to S4 is greater than or equal to 0.4 and less than or equal to 1; and / or,

[0042] The S3 is greater than or equal to 0.1 mm 2 and less than or equal to 4mm 2 ; and / or,

[0043] The S4 is greater than or equal to 0.2mm 2 and less than or equal to 7mm 2 .

[0044] In one possible implementation, in the thickness direction of the positive electrode sheet, the perimeter of the projection of the arc-shaped protrusion is L1, and the perimeter of the projection of the straight protrusion is L2, wherein L1≤L2.

[0045] In one possible implementation, the ratio of L1 to L2 is greater than or equal to 0.3 and less than or equal to 1; and / or,

[0046] The L1 is greater than or equal to 2 mm and less than or equal to 7 mm; and / or,

[0047] The L2 is greater than or equal to 2 mm and less than or equal to 10 mm.

[0048] Secondly, this utility model provides a battery, including the battery cell described above.

[0049] This utility model provides a battery cell and a battery. A first region of the positive electrode sheet has multiple first recesses, and a second region has multiple second recesses, thereby improving the overall deformation capability of the positive electrode sheet. Furthermore, it can store electrolyte. A first region of the positive electrode sheet has multiple first protrusions, and a second region has multiple second protrusions, which can support the negative electrode sheet. The gaps between adjacent first protrusions and adjacent second protrusions can store electrolyte. Therefore, when the positive and negative electrodes of the lithium-ion battery are compressed, the electrolyte between the electrodes is sufficient, improving the wetting effect, suppressing interface deterioration, and thus improving the cycle performance of the battery.

[0050] By providing multiple second protrusions in the second region of the positive electrode, the winding stress of the second region on the outside of the cell can be released, thereby reducing the stress difference between the two sides of the second region. During the battery production process, the second region of the positive electrode is less likely to be curled or wrinkled, thus reducing the likelihood of interface problems at the location of the cell in the second region. This can reduce the risk of lithium plating during battery cycling and improve battery safety.

[0051] By making the spacing between two adjacent second protrusions on the second region of the positive electrode greater than the spacing between two adjacent first protrusions on the first region, the second protrusions in the second region can be avoided from being too dense. This prevents the second region from being crushed during the process of setting the second concave-convex structure, which could lead to damage to the electrode, causing a short circuit inside the cell, or even a fire or explosion. This avoids introducing safety risks and further ensures the safety of the battery. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of the structure of a battery cell in related technologies;

[0054] Figure 2 for Figure 1 A schematic diagram of the cross-section of the positive electrode plate in the diagram;

[0055] Figure 3 This is a top view of the first side of a positive electrode sheet before winding, as provided in Embodiment 1 of the present invention.

[0056] Figure 4 for Figure 3 A top view of the second side of the positive electrode before it is wound;

[0057] Figure 5 for Figure 3 A cross-sectional schematic diagram of two adjacent first protrusions in the middle;

[0058] Figure 6 for Figure 3 A cross-sectional schematic diagram of two adjacent second protrusions in the middle;

[0059] Figure 7 for Figure 3 A top view of the first side of the positive electrode sheet after it has been wound and then unwound.

[0060] Figure 8 for Figure 3 A top view of the second side of the positive electrode plate after it has been unwound from its coiled state;

[0061] Figure 9 for Figure 7 A schematic diagram of the cross-section of two adjacent circular arc regions protruding in the image;

[0062] Figure 10 for Figure 7 A schematic diagram of the cross-section of two adjacent straight sections protruding;

[0063] Figure 11 A top view of the first side of a positive electrode sheet provided in Embodiment 2 of this utility model when it is unwound after being wound.

[0064] Figure 12 for Figure 11 A top view of the second side of the positive electrode plate after it has been unwound from its coiled state;

[0065] Figure 13 This is a schematic diagram showing the cracking that occurs after the positive electrode sheet has been embossed.

[0066] Figure 14 This is a schematic diagram showing a positive electrode sheet that has not been crushed after being embossed.

[0067] Explanation of reference numerals in the attached figures:

[0068] 10 - Positive electrode plate; 10a - First region;

[0069] 10b - Second region; 10c - Third region;

[0070] 101 - First side; 102 - Second side;

[0071] 11-First current collector; 12-First active material layer;

[0072] 10a1-the first convex part; 10a2-the first concave part;

[0073] 10a3 - First clearance section; 10b1 - Second convex section;

[0074] 10b2-the second concave part; 10b3-the second avoidance part;

[0075] 10e - Circular arc region; 10d - Flat region;

[0076] 10e1 - convexity in the arc area; 10d1 - convexity in the straight area;

[0077] 20 - Negative electrode; 30 - Separator. Detailed Implementation

[0078] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0079] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0080] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "fixation," 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 mechanical connection, an electrical connection, or a connection that allows communication between the components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0081] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0082] In the above description, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0083] See Figure 1 and Figure 2 As shown, the lithium-ion battery cell is formed by winding a positive electrode 10, a separator 30, and a negative electrode 20. The cell includes alternating arc-shaped regions and planar regions.

[0084] The positive electrode 10 includes a first region 10a, a second region 10b, and a third region 10c connected in sequence. Both sides of the first region 10a contain active material coatings, the second region 10b contains active material coatings on only one side, and neither side of the third region 10c contains active material coatings.

[0085] Since the second region 10b of the positive electrode 10 contains an active material coating on only one side, its resistance to compression and stretching is weak, resulting in a stress difference in the second region 10b during winding. During the battery production process, the second region of the positive electrode 10 becomes curled and wrinkled, and interface problems occur at the location of the cell in the second region, leading to lithium plating problems during battery cycling.

[0086] Furthermore, the compression between the positive electrode 10 and the negative electrode 20 in the lithium-ion battery leads to insufficient electrolyte and poor wetting between them, making the interface prone to deterioration and affecting the cycle performance of the lithium-ion battery. The inventors' research revealed that this problem arises because the curved portion of the lithium-ion battery cell experiences significant stress accumulation, resulting in inherent compression between the electrodes. Additionally, the expansion of the positive electrode 10 and the negative electrode 20 during charging and discharging exacerbates this compression. This compression extends beyond the curved region to the planar region, causing poor support in the interlayer structure of the electrodes, leading to insufficient electrolyte and poor wetting between the positive electrode 10 and the negative electrode 20, resulting in interface deterioration and affecting the cycle performance of the lithium-ion battery.

[0087] To address the aforementioned problems, this utility model provides a battery cell and a battery. Multiple recesses are provided in the first and second regions of the positive electrode to store electrolyte, and multiple protrusions are provided in the first and second regions of the positive electrode to support the negative electrode. The gaps between adjacent protrusions can store electrolyte. Therefore, when the positive and negative electrodes of the lithium-ion battery are compressed, sufficient electrolyte is provided between the electrodes, improving the wetting effect, suppressing interface deterioration, and ultimately improving the battery's cycle performance.

[0088] This utility model provides a battery cell and a battery. By providing multiple protrusions in the second region of the positive electrode, the stress in the second region can be released, thereby reducing the stress difference between the two sides of the second region. During the battery production process, the second region of the positive electrode is less likely to curl or wrinkle, thus the interface problem in the location of the battery cell in the second region is less likely to occur. This can reduce the risk of lithium plating during battery cycling and improve battery safety.

[0089] Since the first region 10a of the positive electrode 10 contains active material coatings on both sides, while the second region 10b contains active material coatings on only one side, the second region 10b has poor ductility compared to the first region 10a. When the first region 10a and the second region 10b are provided with concave and convex structures, the convex parts of the second region are too dense, which may cause the second region to be crushed during the process of setting the second concave and convex structure, which will introduce safety risks.

[0090] This utility model embodiment provides a battery cell and a battery. By making the distance between two adjacent second protrusions on the second region of the positive electrode sheet greater than the distance between two adjacent first protrusions on the first region, the second protrusions in the second region can be avoided from being too dense, which would cause the second region to be crushed during the process of setting the second concave-convex structure, thus avoiding the introduction of safety risks and further ensuring the safety of the battery.

[0091] The battery cell and battery provided in the embodiments of this utility model will be described in detail below with reference to specific examples.

[0092] This utility model provides a battery cell, including a positive electrode 10, a negative electrode, and a separator located between the positive electrode 10 and the negative electrode.

[0093] A battery cell is formed by stacking and winding the positive electrode 10, negative electrode 30, and separator. Specifically, the positive electrode 10, separator 30, and negative electrode 30 are stacked together in sequence and then wound from the starting end to the ending end to form the battery cell. It should be noted that the starting end of the positive electrode 10 and negative electrode 30 is the starting end of the battery cell, located on the inner side of the battery, while the ending end of the positive electrode 10 and negative electrode 30 is the ending end of the battery cell, located on the outer side of the battery. The winding direction of the battery cell is the direction of extension from the starting end to the ending end.

[0094] exist Figure 3 and Figure 4 The middle image shows the state of the positive electrode plate before it is wound into 10 sections.

[0095] See Figure 3 and Figure 4 As shown, the positive electrode 10 includes a first current collector 11 and a first active material layer 12 located on both sides of the first current collector 11. In some examples, aluminum foil or a composite current collector can be used as the first current collector, which may include a polymer layer and two aluminum layers located on opposite sides of the polymer layer.

[0096] The positive electrode 10 includes a first region 10a on both sides of the first current collector 11, where a first active material layer 12 is disposed.

[0097] The positive electrode 10 includes a second region 10b in which a first active material layer 12 is disposed only on one side of the first current collector 11. That is, the first active material layer 12 is disposed on one side of the first current collector 11 in the second region 10b, and no first active material layer 12 is disposed on the other side. The second region 10b is connected to the first region 10a.

[0098] In the battery cell, the second region 10b is located on the side of the first region 10a that is farther from the inside of the cell. That is to say, in the battery cell, the first region 10a is closer to the inside of the cell than the second region 10b. The second region 10b includes a portion corresponding to the outermost positive electrode plate 10.

[0099] The positive electrode 10 also includes a third region 10c connected to the second region 10b. The first active material layer 12 is not provided on either side of the first current collector 11 in the third region 10c, that is, the third region 10c only provides the first current collector 11.

[0100] The length direction of the positive electrode 10 is the X-axis direction, the width direction of the positive electrode 10 is the Y-axis direction, and the height direction of the positive electrode 10 is the Z-axis direction (see...). Figure 5 and Figure 6 (As shown). The X-axis, Y-axis, and Z-axis are perpendicular to each other.

[0101] The positive electrode 10 has a first side 101 and a second side 102 disposed opposite to each other (see Figure 5 and Figure 6 (As shown). The positive electrode 10 is on the side with the +Z axis as the first side 101. The positive electrode 10 is on the side with the -Z axis as the second side 102.

[0102] The positive electrode 10 has a plurality of spaced-apart first convex and concave structures formed on the first region 10a. Exemplarily, the first region 10a of the positive electrode 10 is embossed to form the first convex and concave structures before the positive electrode 10 is wound.

[0103] The first concave-convex structure forms a first protrusion 10a1 on one side of the positive electrode sheet 10 in the thickness direction, and a first concave portion 10a2 on the other side of the positive electrode sheet 10 in the thickness direction. That is to say, the first concave-convex structure corresponds to one first protrusion 10a1 and one first concave portion 10a2 respectively. For example, see [link to example]. Figure 3 and Figure 4 As shown, the first concave-convex structure can form a first protrusion 10a1 on the first side 101 of the positive electrode 10, and the first concave-convex structure can form a first concave portion 10a2 on the second side 102 of the positive electrode 10.

[0104] The positive electrode 10 has a plurality of spaced-apart second convex and concave structures formed on the second region 10b. Exemplarily, the second region 10b of the positive electrode 10 is embossed to form the second convex and concave structures before the positive electrode 10 is wound.

[0105] The second concave-convex structure forms a second protrusion 10b1 on one side of the positive electrode sheet 10 in the thickness direction, and a second concave portion 10b2 on the other side of the positive electrode sheet 10 in the thickness direction. That is to say, the second concave-convex structure corresponds to one second protrusion 10b1 and one second concave portion 10b2 respectively. For example, see [reference needed]. Figure 3 and Figure 4 As shown, the second concave-convex structure can form a second protrusion 10b1 on the first side 101 of the positive electrode 10, and the first concave-convex structure can form a second concave portion 10b2 on the second side 102 of the positive electrode 10.

[0106] The battery cell provided in this embodiment of the present invention has a plurality of first recesses 10a2 provided in the first region 10a of the positive electrode 10 and a plurality of second recesses 10b2 provided in the second region 10b, thereby improving the overall deformation capability of the positive electrode. Furthermore, it can store electrolyte. The plurality of first protrusions 10a1 provided in the first region 10a of the positive electrode 10 and a plurality of second protrusions 10b1 provided in the second region 10b can support the negative electrode. The gaps between adjacent first protrusions 10a1 and adjacent second protrusions 10b1 can store electrolyte. Thus, when the positive electrode 10 and the negative electrode are squeezed together in the lithium-ion battery, the electrolyte between the electrodes is sufficient, improving the wetting effect, suppressing interface deterioration, and thereby improving the cycle performance of the battery.

[0107] By providing multiple second protrusions 10b1 in the second region 10b of the positive electrode 10, the stress in the second region 10b can be released, reducing the stress difference between the two sides of the second region 10b. During the battery production process, the second region 10b of the positive electrode 10 is less prone to curling and wrinkling, thus reducing the likelihood of interface problems at the location of the cell in the second region 10b. This can reduce the risk of lithium plating during battery cycling and improve battery safety.

[0108] The negative electrode includes a second current collector and a second active material layer (not shown in the figure) located on both sides of the second current collector.

[0109] In one possible implementation, see Figure 5 and Figure 6 As shown, the distance between two adjacent second protrusions 10b1 is D2, and the distance between two adjacent first protrusions 10a1 is D1, where D2 > D1. This arrangement avoids the second protrusions 10b1 in the second region 10b being too densely packed, which could cause the second region 10b to be crushed during the process of setting the second concave-convex structure, leading to damage to the electrode sheets, causing internal short circuits in the cell, and potentially resulting in cell fires and explosions. Therefore, this arrangement avoids introducing safety risks and further ensures the safety of the battery.

[0110] The distance between two adjacent first protrusions 10a1 can be defined as the distance between the centers of two adjacent first protrusions 10a1.

[0111] The distance between two adjacent second protrusions 10b1 can be defined as the distance between the centers of two adjacent second protrusions 10b1.

[0112] In some examples, the ratio of D2 to D1 is greater than 1 and less than or equal to 1.5. For example, the ratio of D2 to D1 can be 1.1, 1.2, 1.3, 1.4, or 1.5. Of course, this ratio can also be other values, and those skilled in the art can choose according to their needs; this embodiment does not limit this. To avoid an excessively large ratio between the spacing between two adjacent second protrusions 10b1 and the spacing between two adjacent first protrusions 10a1, which would make the second protrusions 10b1 of the second region 10b too sparse, resulting in insufficient support for the second region 10b in the battery cell and difficulty in releasing stress, local interface problems are prone to occur in the second region 10b of the positive electrode 10, leading to lithium plating during battery cycling.

[0113] D1 is greater than or equal to 1 mm and less than or equal to 8 mm. For example, the value of D1 can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, or 8 mm. Of course, this spacing can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids the spacing between two adjacent first protrusions 10a1 being too small, making the first protrusions 10a1 of the first region 10a too dense, which would make the first region 10a prone to powder shedding during the process of setting the first concave-convex structure. On the other hand, it avoids the spacing between two adjacent first protrusions 10a1 being too large, making the first protrusions 10a1 of the first region 10a too sparse, which would result in insufficient support for the first region 10a in the cell, which would be insufficient to solve the problem of poor local interface and lithium plating caused by low electrolyte retention and poor wetting between the electrodes.

[0114] D2 is greater than or equal to 3 mm and less than or equal to 10 mm. For example, the value of D2 can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm. Of course, the distance D1 between two adjacent first protrusions 10a1 can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids the distance between two adjacent second protrusions 10b1 being too small, making the second protrusions 10b1 of the second region 10b too dense, which would easily cause the second region 10b to shed powder during the process of setting the second concave-convex structure. On the other hand, it avoids the distance between two adjacent second protrusions 10b1 being too large, making the second protrusions 10b1 of the second region 10b too sparse, which would make the second region 10b have insufficient support in the cell and be insufficient to solve the problem of poor local interface and lithium plating caused by low electrolyte retention and poor wetting between the electrodes.

[0115] In one possible implementation, see Figure 3 and Figure 4 As shown, in the thickness direction of the positive electrode 10, the height of the second protrusion 10b1 is H2, and the height of the first protrusion 10a1 is H1, where H2 ≤ H1. This is mainly because the second region has only one side of active material layer, and its resistance to compression and stretching is weaker than that of the first region. Therefore, this setting can avoid the second protrusion 10b1 of the second region 10b being too high, which would cause the second region 10b to be crushed due to excessive pressure during the setting of the second concave-convex structure, thus avoiding the introduction of safety risks and further ensuring the safety of the battery.

[0116] The height of the first protrusion 10a1 can be defined as the height of the vertex of the first protrusion 10a1 above the reference plane in the thickness direction of the positive electrode 10. The reference plane is the plane where the portion of the positive electrode 10 on the first side 101 that has not been embossed is located; that is, the reference plane is the plane where the positive electrode 10 is located on the first side 101 before it has been embossed.

[0117] The height of the second protrusion 10b1 can be defined as the height of the vertex of the second protrusion 10b1 above the reference plane in the thickness direction of the positive electrode 10.

[0118] When the height of the first protrusion 10a1 and the height of the second protrusion 10b1 are both greater than 15um, the height of the first protrusion 10a1 and the height of the second protrusion 10b1 are not the same.

[0119] When the height of the first protrusion 10a1 and the height of the second protrusion 10b1 are both less than or equal to 15um, the height of the first protrusion 10a1 and the height of the second protrusion 10b1 may be the same or different.

[0120] In some examples, the ratio of H2 to H1 in the thickness direction of the positive electrode 10 is greater than or equal to 1 / 5 and less than or equal to 3 / 5. For example, the ratio of H2 to H1 can be 1 / 5, 3 / 10, 2 / 5, 1 / 2, or 3 / 5. Of course, this ratio can also be other values, and those skilled in the art can choose according to their needs; this embodiment does not limit this. Thus, on the one hand, it avoids the ratio of the height H2 of the second protrusion 10b1 to the height of the first protrusion 10a1 being too small, resulting in the second protrusion 10b1 of the second region 10b being too small, causing insufficient support for the second region 10b in the cell, which is insufficient to solve the problem of poor local interface and lithium plating caused by low electrolyte retention and poor wetting between the electrodes. On the other hand, it avoids the ratio of the height H2 of the second protrusion 10b1 to the height of the first protrusion 10a1 being too large, resulting in the height of the second protrusion 10b1 of the second region 10b being too close to the height of the first protrusion of the first region, causing the second region 10b to be crushed during the setting of the second concave-convex structure due to its weak resistance to compression and tension.

[0121] H1 can be greater than or equal to 3um and less than or equal to 100um. For example, the value of H1 can be 3um, 10um, 20um, 30um, 40um, 50um, 60um, 70um, 80um, 90um, or 100um. Of course, this height can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids the first protrusion 10a1 being too small, resulting in insufficient support for the first region 10a in the battery cell; on the other hand, it avoids the first protrusion 10a1 being too large, resulting in the first region 10a being crushed during the setting of the first concave-convex structure.

[0122] H2 can be greater than or equal to 3µm and less than or equal to 35µm. For example, the value of H2 can be 3µm, 5µm, 10µm, 15µm, 20µm, 25µm, 30µm, or 35µm. Of course, this height can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids the second protrusion 10b1 being too small, resulting in insufficient support for the second region 10b in the battery cell; on the other hand, it avoids the second protrusion 10b1 being too large, resulting in the second region 10b being crushed during the process of setting the second concave-convex structure.

[0123] In one possible implementation, in the thickness direction of the positive electrode 10, the projected area of ​​the first protrusion 10a1 is S1, and the projected area of ​​the second protrusion 10b1 is S2, where S2 > S1. This arrangement avoids the second protrusion 10b1 being too small, which would result in the second protrusions 10b1 in the second region 10b being too densely packed. This would cause the second region 10b to be subjected to excessively concentrated stress during the construction of the second concave-convex structure, preventing stress release and potentially leading to the second region 10b being crushed. Therefore, this arrangement avoids introducing safety risks and further ensures the safety of the battery.

[0124] Before the positive electrode 10 is wound, the area of ​​the projection of the first protrusion 10a1 in the thickness direction of the positive electrode 10 is S1.

[0125] Before the positive electrode 10 is wound, the area of ​​the projection of the second protrusion 10b1 in the thickness direction of the positive electrode 10 is S2.

[0126] In some examples, the ratio of S2 to S1 is greater than or equal to 1.2 and less than or equal to 3. For example, the ratio of S2 to S1 can be 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, or 3. Of course, the ratio of S2 to S1 can also be other values, and those skilled in the art can choose according to their needs; this embodiment does not limit this. Thus, on the one hand, the ratio of S2 to S1 is avoided from being too small, because if the projected area of ​​the second protrusion 10b1 is close to the projected area of ​​the first protrusion, their density is similar, and the force exerted when setting the concave-convex structure is also similar. Considering that the second region only has an active material layer on one side, its resistance to compression and stretching is weaker than that of the first region. This setting can prevent the second region 10b from being crushed during the setting of the second concave-convex structure. On the other hand, the ratio of S2 to S1 is avoided from being too large, which would make the projected area of ​​the second protrusion 10b1 too large, resulting in the second protrusion 10b1 of the second region 10b being too sparse, making the second region 10b insufficiently supported in the cell, and insufficient to solve the problem of poor local interface and lithium plating caused by low electrolyte retention and poor wetting between the electrodes.

[0127] S1 can be greater than or equal to 0.1 mm 2 and less than or equal to 7mm 2 For example, the value of S1 can be 0.1 mm. 2 0.5mm 2 1mm 2 1.5mm 2 2mm 2 3mm 2 4mm 2 5mm 2 6mm 2 or 7mm 2 Of course, S1 can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids S1 being too small, which would cause the first protrusions 10a1 of the first region 10a to be too dense, thereby avoiding the first region 10a being crushed during the process of setting the first concave-convex structure. On the other hand, it avoids S1 being too large, which would cause the first protrusions 10a1 of the first region 10a to be too sparse, resulting in insufficient support for the first region 10a in the battery cell.

[0128] S2 can be greater than or equal to 0.5mm 2 and less than or equal to 10mm 2 For example, the value of S2 can be 0.5mm. 2 1mm 2 2mm 2 3mm 2 4mm 25mm 2 6mm 2 7mm 2 8mm 2 9mm 2 or 10mm 2 Of course, S2 can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids S2 being too small, which would cause the second protrusions 10b1 of the second region 10b to be too dense, thereby avoiding the second region 10b being crushed during the process of setting the second concave-convex structure. On the other hand, it avoids S2 being too large, which would cause the second protrusions 10b1 of the second region 10b to be too sparse, resulting in insufficient support for the second region 10b in the battery cell.

[0129] In one possible implementation, in the winding direction of the positive electrode 10, the distance between adjacent first protrusions 10a1 and second protrusions 10b1 is greater than or equal to 2 mm and less than or equal to 10 mm. For example, in the winding direction of the positive electrode 10, the distance between adjacent first protrusions 10a1 and second protrusions 10b1 can be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm. Of course, this distance can also be other values, and those skilled in the art can select according to their needs; this embodiment does not limit this. Thus, on the one hand, it avoids the situation where the distance between adjacent first protrusions 10a1 and second protrusions 10b1 is too small in the winding direction of the positive electrode 10. This would easily cause the first protrusions 10a1 in the first region 10a and the second protrusions 10b1 in the second region 10b to overlap when setting the first and second concave-convex structures, resulting in redundant design. Moreover, the formation process of the two first and second protrusions with different depths and sizes would result in uneven stress on the electrode, which could even easily lead to the problem of the positive electrode 10 breaking. On the other hand, it avoids the situation where the distance between adjacent first protrusions 10a1 and second protrusions 10b1 is too large in the winding direction of the positive electrode 10. This would result in insufficient support for the portion between adjacent first protrusions 10a1 and second protrusions 10b1 in the cell, which would be insufficient to solve the problem of poor local interface and lithium plating caused by low electrolyte retention and poor wetting between the electrodes.

[0130] In the winding direction of the positive electrode 10, the distance between adjacent first protrusions 10a1 and second protrusions 10b1 can be understood as the distance D3 between adjacent first protrusions 10a1 and second protrusions 10b1 in the length direction of the positive electrode 10 before winding (see [reference]). Figure 3 (As shown).

[0131] In one possible implementation, the boundary between the first region 10a and the second region 10b in the winding direction of the positive electrode 10 is designated as the first boundary. See also Figure 3 As shown, the first boundary can be equivalent to the boundary A between the first region 10a and the second region 10b in the length direction of the positive electrode 10.

[0132] In the winding direction of the positive electrode 10, the boundary between the second region 10b and the third region 10c is called the second boundary. See also Figure 3 As shown, the second boundary can be equivalent to the boundary B between the second region 10b and the third region 10c in the length direction of the positive electrode 10.

[0133] In the winding direction of the positive electrode 10, the distance between the first protrusion 10a1 of the first region 10a and the first boundary can be understood as: in Figure 3 In the positive electrode 10, the distance D4 between the first protrusion 10a1 of the first region 10a and the junction A is in the length direction of the positive electrode 10.

[0134] In the winding direction of the positive electrode 10, the distance between the first protrusion 10a1 of the first region 10a and the first boundary is greater than or equal to 1 mm. For example, in the winding direction of the positive electrode 10, the distance between the first protrusion 10a1 of the first region 10a and the first boundary can be 1 mm, 2 mm, 3 mm, 5 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, or 100 mm. Of course, this distance can also be other values, and those skilled in the art can select it according to their needs. This embodiment does not limit this. In this way, the distance between the first protrusion 10a1 and the first boundary in the first region 10a is not too small in the winding direction of the positive electrode 10, so that the first protrusion 10a1 and the first boundary are too close. Since the boundary is the junction of the double active layer and the single active layer, uneven stress is likely to occur, which may lead to damage or even breakage of the positive electrode 10 at the first boundary during the setting of the first concave-convex structure. Thus, the first protrusion 10a1 of the first region 10a can avoid the first boundary.

[0135] In the winding direction of the positive electrode 10, the distance between the second protrusion 10b1 of the second region 10b and the first boundary can be understood as: in Figure 3 In the middle, along the length direction of the positive electrode 10, the distance D5 between the second protrusion 10b1 of the second region 10b and the junction A.

[0136] In the winding direction of the positive electrode 10, the distance between the second protrusion 10b1 of the second region 10b and the first boundary is greater than or equal to 1 mm. For example, the distance between the second protrusion 10b1 of the second region 10b and the first boundary can be 1 mm, 2 mm, 3 mm, 5 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, or 100 mm. Of course, this distance can also be other values, and those skilled in the art can select according to their needs. This embodiment does not limit this. In this way, it avoids the distance between the second protrusion 10b1 of the second region 10b and the first boundary being too small in the winding direction of the positive electrode 10, making the distance between the second protrusion 10b1 and the first boundary too close. Since the boundary is the junction of the double-layer active layer and the single-sided active layer, uneven stress is likely to occur, which may lead to damage or even breakage of the positive electrode 10 at the first boundary during the process of setting the second concave-convex structure. Therefore, the second protrusion 10b1 of the second region 10b can avoid the first boundary.

[0137] In one possible implementation, see Figure 3 and Figure 4 As shown, in the width direction of the positive electrode 10, a first clearance portion 10a3 is provided on at least one edge of the first region 10a, and a second clearance portion 10b3 is provided on at least one side of both sides of the second region 10b.

[0138] In the width direction of the positive electrode 10, the first region 10a may have a first clearance portion 10a3 on only one side, or the first clearance portion 10a3 may be provided on both sides.

[0139] In some examples, in the width direction of the positive electrode 10, the first region 10a, after removing all the areas where the first protrusions 10a1 are located, is the first clearance region 10a3.

[0140] In the width direction of the positive electrode 10, the second region 10b may have a second clearance portion 10b3 on only one side, or the second clearance portion 10b3 may be provided on both sides.

[0141] In some examples, in the width direction of the positive electrode 10, the second region 10b, after removing all the areas where the second protrusions 10b1 are located, is the second clearance portion 10b3.

[0142] In the thickness direction of the positive electrode 10, the projection of the first protrusion 10a1 does not coincide with the projection of the first clearance portion 10a3, that is to say, there is no first protrusion 10a1 on the first clearance portion 10a3; in the thickness direction of the positive electrode 10, the projection of the second protrusion 10b1 does not coincide with the projection of the second clearance portion 10b3, that is to say, there is no second protrusion 10b1 on the second clearance portion 10b3.

[0143] It is worth mentioning that during the winding process, it is necessary to ensure that the edge of the negative electrode sheet covers the edge of the positive electrode sheet. During winding, positioning equipment such as a laser device is used to position the edges of the electrode sheets for correction. The first clearance portion 10a3 and the second clearance portion 10b3 prevent unevenness at the edge of the positive electrode sheet 10 due to the presence of the first and second uneven structures, ensuring effective positioning during winding. Furthermore, the first clearance portion 10a3 and the second clearance portion 10b3 also prevent "powder shedding" from the edge of the first active material layer 12 due to the first and second uneven structures.

[0144] In one possible implementation, the shape of the projection of the first protrusion 10a1 in the thickness direction of the positive electrode 10 is any one of a circle, a near-circular shape, a polygon, an island shape, etc.

[0145] In the thickness direction of the positive electrode 10, the projection shape of the second protrusion 10b1 can be any one of the following: circular, near-circular, polygonal, island-shaped, etc.

[0146] Among them, a circle-like shape refers to a shape in which part of it is an arc, such as an ellipse.

[0147] An island shape refers to the shape formed by islands.

[0148] In some examples, the projected shapes of each first protrusion 10a1 are the same in the thickness direction of the positive electrode 10, and the projected shapes of each second protrusion 10b1 are the same. See, for example, [link to example]. Figure 3 and Figure 4 As shown, in the thickness direction of the positive electrode 10, the projection shape of each first protrusion 10a1 is circular, and the projection shape of the second protrusion 10b1 is rhomboid.

[0149] exist Figure 7 and Figure 8 The state of the positive electrode 10 is the state when the positive electrode 10 is unwound after being wound.

[0150] In one possible implementation, see Figure 7 and Figure 8 As shown, in the winding direction of the positive electrode 10, the positive electrode 10 includes alternately arranged straight regions 10d and arc regions 10e. The arc region 10e of the positive electrode 10 is arc-shaped in the cell, and the straight region 10d is straight in the cell.

[0151] Among them, see Figure 7As shown, the first convex portion located in the arc region 10e of the positive electrode 10 is the arc region convexity 10e1, and the first convex portion located in the flat region 10d of the positive electrode 10 is the flat region convexity 10d1. It can be understood that the arc region convexity 10e1 includes the portion located in the first region and / or the portion located in the second region, and the flat region convexity 10d1 is similarly defined.

[0152] See Figure 9 and Figure 10 As shown, in the thickness direction of the positive electrode 10, the height of the arc-shaped protrusion 10e1 is H3, and the height of the flat protrusion 10d1 is H4, where H3 > H4. In the battery cell, since the degree of compression between the positive electrode 10 and the negative electrode in the arc-shaped region is greater than that in the flat region, the greater height of the arc-shaped protrusion 10e1 compared to the flat protrusion 10d1 allows for a larger amount of electrolyte to be stored between adjacent arc-shaped protrusions 10e1. This ensures sufficient electrolyte between the positive electrode 10 and the negative electrode in the arc-shaped region, improving the wetting effect.

[0153] In some examples, the ratio of H3 to H4 is greater than 1 and less than or equal to 1.5. For example, the ratio of H3 to H4 can be 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, or 1.5. Of course, the ratio can also be other values, and those skilled in the art can choose according to their needs; this embodiment does not limit this. Thus, on the one hand, it avoids the ratio of the height of the arc-shaped protrusion 10e1 to the height of the flat-shaped protrusion 10d1 being too small, resulting in insufficient support for the negative electrode plate by the arc-shaped protrusion 10e1 and insufficient electrolyte between the positive electrode plate 10 and the negative electrode plate in the arc-shaped area. On the other hand, it avoids the ratio of the height of the arc-shaped protrusion 10e1 to the height of the flat-shaped protrusion 10d1 being too large, resulting in excessive height of the arc-shaped protrusion 10e1. This could lead to poor adhesion between the arc-shaped protrusion 10e1 and the separator interface, failing to achieve the benefits of sufficient electrolyte wetting and pre-reserved expansion space to prevent cell deformation due to compression, and instead causing interface deterioration.

[0154] H3 can be greater than or equal to 5 μm and less than or equal to 100 μm. For example, the value of H3 can be 5 μm, 6 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, or 100 μm. Of course, this height can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids the height of the arc-shaped protrusion 10e1 being too small, which would result in insufficient support for the negative electrode in the arc-shaped region 10e of the first region 10a, leading to a smaller spacing between the electrodes and insufficient electrolyte between the electrodes, resulting in poor wetting. On the other hand, it avoids the height of the arc-shaped protrusion 10e1 being too large, which could cause poor adhesion at the interface of the arc-shaped region 10e of the first region 10a due to the compression between the positive electrode 10 and the negative electrode in the arc-shaped region. This would not achieve the benefits of sufficient electrolyte wetting and reserving expansion space in advance to prevent the cell from being squeezed and deformed, but instead cause the interface to deteriorate.

[0155] H4 can be greater than or equal to 3um and less than or equal to 80um. For example, the value of H4 can be 3um, 10um, 20um, 30um, 40um, 50um, 60um, or 80um. Of course, this height can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids the flat region protrusion 10d1 being too small, which would result in insufficient support of the flat region 10d of the first region 10a for the negative electrode, leading to a smaller spacing between the electrodes and insufficient electrolyte between the electrodes, resulting in poor wetting. On the other hand, it avoids the flat region protrusion 10d1 being too large, which could cause poor adhesion of the interface of the flat region 10d of the first region 10a due to the compression between the positive electrode 10 and the negative electrode in the flat region. This would not achieve the benefits of sufficient electrolyte wetting and reserving expansion space in advance to prevent the cell from being squeezed and deformed, but instead cause the interface to deteriorate.

[0156] In one possible implementation, see 9 and Figure 10 As shown, the distance between two adjacent arc-shaped protrusions 10e1 is D6, and the distance between two adjacent flat protrusions 10d1 is D7, where D6 ≤ D7. In the battery cell, since the compression between the positive electrode 10 and the negative electrode in the arc-shaped region is greater than that in the flat region, by making the distance between two adjacent arc-shaped protrusions 10e1 less than or equal to the distance between two adjacent flat protrusions 10d1, the arc-shaped protrusions 10e1 in the first region 10a are more densely packed. This provides more space for the battery cell to store electrolyte in the arc-shaped region, and also provides stronger support for the negative electrode in the arc-shaped region 10e1. Furthermore, it provides compressible space for the expansion of the negative electrode, which can prevent lithium plating in the battery cell during battery cycling.

[0157] The distance between two adjacent arc-shaped protrusions 10e1 can be defined as (see reference). Figure 9 As shown, in the plane formed by the X and Y axes, the distance between the centers of two adjacent circular arc protrusions 10e1 is shown.

[0158] The distance between two adjacent straight-area protrusions 10d1 can be defined as (see reference). Figure 10 As shown, in the plane formed by the X and Y axes, the distance between the centers of two adjacent straight regions protruding 10d1.

[0159] In some examples, the ratio of D6 to D7 is greater than or equal to 0.5 and less than or equal to 1. For example, the ratio of D6 to D7 can be 0.5, 0.6, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 1. Of course, the ratio can also be other values, and those skilled in the art can choose according to their needs; this embodiment does not limit this. Thus, on the one hand, it avoids the ratio of the distance between two adjacent arc-shaped protrusions 10e1 to the distance between two adjacent flat protrusions 10d1 being too small. Compared to the flat area, the arc-shaped area is subjected to greater stress. If the ratio is too small, the arc-shaped area will not have enough space to store electrolyte, making it difficult to effectively solve the lithium plating problem caused by poor wetting. On the other hand, it avoids the ratio of the distance between two adjacent arc-shaped protrusions 10e1 to the distance between two adjacent flat protrusions 10d1 being too large, which would make the arc-shaped protrusions 10e1 in the first region 10a sparse, and the arc-shaped area 10e would not provide sufficient support for the negative electrode. There would be insufficient electrolyte between the positive electrode 10 and the negative electrode in the arc-shaped area, resulting in lithium plating in the cell during battery cycling.

[0160] D6 can be greater than or equal to 1 mm and less than or equal to 5 mm. For example, the value of D6 can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, or 5 mm. Of course, this spacing can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids the spacing between two adjacent arc-shaped protrusions 10e1 being too small, which would make it difficult for the arc-shaped area to have enough space to store electrolyte and effectively solve the lithium plating problem caused by poor wetting. On the other hand, it avoids the spacing D6 between two adjacent arc-shaped protrusions 10e1 being too large, which would result in insufficient support for the negative electrode by the arc-shaped area 10e, and insufficient electrolyte between the positive electrode 10 and the negative electrode in the arc-shaped area, leading to lithium plating in the cell during battery cycling.

[0161] D7 can be greater than or equal to 2 mm and less than or equal to 8 μm. For example, the value of D7 can be 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 5 mm, 6 mm, 7 mm, or 8 mm. Of course, this spacing can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids the spacing between two adjacent flat area protrusions 10d1 being too small, making the flat area protrusions 10d1 of the first region 10a too dense, and avoids the flat area 10d of the first region 10a being crushed during the setting of the first concave-convex structure. On the other hand, it avoids the spacing between two adjacent flat area protrusions 10d1 being too large, making the flat area protrusions 10d1 of the first region 10a sparse, resulting in insufficient support of the flat area 10d of the first region 10a for the negative electrode in the cell, and insufficient electrolyte between the positive electrode 10 and the negative electrode in the flat area, resulting in lithium plating in the cell during battery cycling.

[0162] In one possible implementation, the projected area of ​​the arc-shaped protrusion 10e1 in the thickness direction of the positive electrode 10 is S3, and the projected area of ​​the flat protrusion 10d1 is S4. Wherein, S3 ≤ S4. This arrangement makes the arc-shaped protrusions 10e1 in the first region 10a more densely packed, providing more space for electrolyte storage in the arc-shaped region of the cell, and also providing stronger support for the negative electrode in the arc-shaped region 10e. Furthermore, it provides compressible space for the expansion of the negative electrode, thus preventing lithium plating in the cell during battery cycling.

[0163] When the positive electrode 10 is unwound after being wound, the area of ​​the projected arc-shaped protrusion 10e1 in the thickness direction of the positive electrode 10 is S3.

[0164] When the positive electrode 10 is unwound after being wound, the area of ​​the projected straight region protrusion 10d1 in the thickness direction of the positive electrode 10 is S4.

[0165] In some examples, the ratio of S3 to S4 is greater than or equal to 0.4 and less than or equal to 1. For example, the ratio of S3 to S4 can be 0.4, 0.5, 0.6, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 1. Of course, the ratio of S3 to S4 can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids the ratio of S3 to S4 being too small, which would make the arc-shaped protrusions 10e1 of the first region 10a too dense, and prevent the arc-shaped region 10e of the first region 10a from being crushed during the setting of the first concave-convex structure. On the other hand, it avoids the ratio of S3 to S4 being too large, which would make the arc-shaped protrusions 10e1 of the first region 10a sparse, resulting in insufficient support for the negative electrode plate by the arc-shaped region 10e, and insufficient electrolyte between the positive electrode plate 10 and the negative electrode plate in the arc-shaped region, leading to lithium plating in the cell during battery cycling.

[0166] S3 can be greater than or equal to 0.1mm 2 and less than or equal to 4mm 2 For example, the value of S3 can be 0.1 mm. 2 0.5mm 2 1mm 2 1.5mm 2 2mm 2 2.5mm 2 3mm 2 3.5mm 2 or 4mm 2 Of course, S3 can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids S3 being too small, which would make the arc-shaped protrusions 10e1 of the first region 10a too dense, and prevent the arc-shaped region 10e of the first region 10a from being crushed during the setting of the first concave-convex structure. On the other hand, it avoids S3 being too large, which would make the arc-shaped protrusions 10e1 of the first region 10a sparse, and the arc-shaped region 10e would not provide sufficient support for the negative electrode. This would result in insufficient electrolyte between the positive electrode 10 and the negative electrode in the arc-shaped region, leading to lithium plating in the cell during battery cycling.

[0167] S4 can be greater than or equal to 0.2mm 2 and less than or equal to 7mm 2 For example, the value of S4 can be 0.2 mm. 2 0.5mm 2 1mm 2 1.5mm 2 2mm 2 2.5mm 2 3mm 2 3.5mm 2 4mm2 5mm 2 6mm 2 or 7mm 2 Of course, S4 can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids S4 being too small, which would make the flat area protrusions 10d1 of the first region 10a too dense, and prevent the flat area 10d of the first region 10a from being crushed during the setting of the first concave-convex structure. On the other hand, it avoids S3 being too large, which would make the flat area protrusions 10d1 of the first region 10a sparse, resulting in insufficient support for the negative electrode in the cell, and insufficient electrolyte between the positive electrode 10 and the negative electrode in the flat area, leading to lithium plating in the cell during battery cycling.

[0168] In one possible implementation, in the thickness direction of the positive electrode 10, the perimeter of the projected arc-shaped protrusion 10e1 is L1, and the perimeter of the projected flat protrusion 10d1 is L2, where L1 ≤ L2. This arrangement makes the arc-shaped protrusions 10e1 in the first region 10a more densely packed, providing more space for electrolyte storage in the arc-shaped region and providing stronger support for the negative electrode. It also provides compressible space for the expansion of the negative electrode, preventing lithium plating during battery cycling.

[0169] When the positive electrode 10 is unwound after being wound, the circumference of the projection of the arc-shaped protrusion 10e1 in the thickness direction of the positive electrode 10 is L1.

[0170] When the positive electrode 10 is unwound after being wound, the perimeter of the projection of the straight region protrusion 10d1 in the thickness direction of the positive electrode 10 is L2.

[0171] In some examples, the ratio of L1 to L2 is greater than or equal to 0.3 and less than or equal to 1. For example, the ratio of L1 to L2 can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 1. Of course, the ratio of L1 to L2 can also be other values, and those skilled in the art can choose according to their needs; this embodiment does not limit this. Thus, on the one hand, it avoids the ratio of L1 to L2 being too small, which would cause the arc-shaped protrusions 10e1 of the first region 10a to be too dense, and prevents the arc-shaped region 10e of the first region 10a from being crushed during the setting of the first concave-convex structure. On the other hand, it avoids the ratio of L1 to L2 being too large, which would cause the arc-shaped protrusions 10e1 of the first region 10a to be sparse, resulting in insufficient support for the negative electrode plate by the arc-shaped region 10e, and insufficient electrolyte between the positive electrode plate 10 and the negative electrode plate in the arc-shaped region, leading to lithium plating in the cell during battery cycling.

[0172] L1 can be greater than or equal to 2 mm and less than or equal to 7 mm. For example, the value of L1 can be 2 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, or 7 mm. Of course, L1 can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids L1 being too small, which would make the arc-shaped protrusions 10e1 of the first region 10a too dense, and prevent the arc-shaped region 10e of the first region 10a from being crushed. On the other hand, it avoids L1 being too large, which would make the arc-shaped protrusions 10e1 of the first region 10a sparse, and the arc-shaped region 10e would not provide sufficient support for the negative electrode. This would result in insufficient electrolyte between the positive electrode 10 and the negative electrode in the arc-shaped region, leading to lithium plating in the cell during battery cycling.

[0173] L2 can be greater than or equal to 2 mm and less than or equal to 10 mm. For example, the value of L2 can be 2 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm. Of course, L2 can also be other values, and those skilled in the art can choose according to their needs. This embodiment does not limit this. In this way, on the one hand, it avoids L2 being too small, which would make the flat area protrusions 10d1 of the first region 10a too dense, and prevent the flat area 10d of the first region 10a from being crushed during the setting of the first concave-convex structure. On the other hand, it avoids L2 being too large, which would make the flat area protrusions 10d1 of the first region 10a sparse, resulting in insufficient support for the negative electrode in the first region 10a in the cell, and insufficient electrolyte between the positive electrode 10 and the negative electrode in the flat area, resulting in lithium plating in the cell during battery cycling.

[0174] In one possible implementation, the shape of the projection of the arc-shaped protrusion 10e1 in the thickness direction of the positive electrode 10 is any one of the following: circular, near-circular, polygonal, island-shaped, etc.

[0175] In the thickness direction of the positive electrode 10, the shape of the projection of the straight region protrusion 10d1 can be any one of the following: circular, near-circular, polygonal, island-shaped, etc.

[0176] In some examples, the shape of the projection of the arcuate protrusion 10e1 in the thickness direction of the positive electrode 10 is the same as the shape of the projection of the flat protrusion 10d1. For example, see... Figure 7 and Figure 8 As shown, in the thickness direction of the positive electrode 10, the shape of the projection of the arc region protrusion 10e1 and the shape of the projection of the straight region protrusion 10d1 are both circular.

[0177] In other embodiments, the shape of the projection of the arc-shaped protrusion 10e1 in the thickness direction of the positive electrode 10 is different from the shape of the projection of the flat protrusion 10d1. For example, see... Figure 11 and Figure 12 As shown, in the thickness direction of the positive electrode 10, the projection shape of the arc region protrusion 10e1 is rhomboid, and the projection shape of the straight region protrusion 10d1 is circular.

[0178] This utility model provides a battery, including a battery cell.

[0179] The battery can be one of the following: lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-cadmium battery, etc.

[0180] The battery cell in this embodiment has the same structure as the battery cell provided in any of the above embodiments and can bring the same or similar technical effects. It will not be described in detail here. For details, please refer to the description of the above embodiments.

[0181] The battery of this application will be described in detail below through specific embodiments. The specific differences of the batteries are shown in Table 1.

[0182] Example 1

[0183] 1. Preparation of positive electrode:

[0184] Lithium cobalt oxide + Li₂NiO₂, SP (conductive carbon black), and PVDF are mixed at a mass ratio of 97.6:1.4:1, and NMP is added. The mixture is stirred until homogeneous to prepare a positive electrode slurry. The positive electrode slurry is coated onto both surfaces of an aluminum foil with a thickness of 10 μm. After baking and rolling, the positive electrode slurry forms a positive electrode active material layer with a thickness of 100 μm. The positive electrode sheet includes a first region 10a, a second region 10b, and a third region 10c. The first region 10a is the region where the positive electrode active material layer is formed on both sides of the aluminum foil. The second region 10b is the region where the positive electrode active material layer is formed only on one side of the aluminum foil. The third region 10c is the region where there is no positive electrode active material layer on either side of the aluminum foil.

[0185] The positive electrode sheet passes through a roller and is embossed from one side of the positive electrode sheet to the other side along the thickness direction of the positive electrode sheet. Multiple first concave-convex structures are formed on the first region 10a, and multiple second concave-convex structures are formed on the second region 10b.

[0186] The first concave-convex structure forms a first protrusion 10a1 on one side of the positive electrode sheet in the thickness direction, and a first concave portion 10a2 on the other side of the positive electrode sheet in the thickness direction.

[0187] The second uneven structure forms a second protrusion 10b1 on one side of the positive electrode sheet in the thickness direction. The second uneven structure forms a second concave portion 10b2 on the other side of the positive electrode sheet in the thickness direction.

[0188] The distance between two adjacent second protrusions 10b1 is 3mm, that is, D2 is 3mm.

[0189] The height of the second protrusion 10b1 is 3um, that is, H2 is 3um.

[0190] The projected area of ​​the second protrusion 10b1 in the thickness direction of the positive electrode is S2. S2 is 1.2 mm. 2 .

[0191] 2. Negative electrode preparation:

[0192] The silicon-doped carbon negative electrode active material was mixed with SP (conductive carbon black), CMC-Li and PAA in a mass ratio of 97:0.4:0.1:2.5, and deionized water was added to prepare a negative electrode slurry. The negative electrode slurry was coated on both surfaces of a copper foil, and after baking and rolling, a negative electrode sheet with a thickness of 230 μm was obtained.

[0193] 3. Diaphragm preparation:

[0194] The polyethylene diaphragm was produced using conventional techniques and has a thickness of 10 μm.

[0195] 4. Assembly:

[0196] The positive electrode, separator, and negative electrode are wound together to obtain the battery cell.

[0197] The battery cells then undergo packaging, baking, electrolyte injection, formation, secondary sealing, sorting, and OCV to obtain the battery. The electrolyte is a commercially available conventional electrolyte, and the lithium salt in it is LiFP6.

[0198] After the positive electrode is unfolded, in the thickness direction of the positive electrode, the height of the arc region protrusion 10e1 is 15um, that is, H3 is 15um, and the height of the straight region protrusion 10d1 is 14um, that is, H4 is 14um.

[0199] The distance between two adjacent arc-shaped protrusions 10e1 is 2mm, that is, D6 is 2mm. The distance between two adjacent straight protrusions 10d1 is 2mm, that is, D7 is 2mm.

[0200] After the positive electrode is unfolded, the projected area of ​​the arc-shaped protrusion 10e1 in the thickness direction of the positive electrode is S3, and the projected area of ​​the straight protrusion 10d1 is S4. S3 is 1 mm. 2 S4 is 1mm. 2 .

[0201] After the positive electrode is unfolded, in the thickness direction of the positive electrode, the perimeter of the projection of the arc-shaped protrusion 10e1 is L1, and the perimeter of the projection of the straight protrusion 10d1 is L2. L1 is 7mm. L2 is 7mm.

[0202] Example 2

[0203] Example 2 was performed in accordance with Example 1, except that D6 was 2.9 mm and D7 was 2.9 mm.

[0204] Example 3

[0205] Example 3 was carried out in accordance with Example 1, except that D6 was 1 mm.

[0206] Example 4

[0207] Example 4 was performed in accordance with Example 1, except that D6 was 1.9 μm and D7 was 1.9 μm.

[0208] Example 5

[0209] Example 5 was carried out in accordance with Example 1, except that D6 was 3um.

[0210] Example 6

[0211] Example 6 was carried out in accordance with Example 1, except that D6 was 0.9 μm.

[0212] Example 7

[0213] Example 7 was carried out with reference to Example 1, except that H3 was 5 μm and H4 was 5 μm.

[0214] Example 8

[0215] Example 8 was carried out in accordance with Example 1, except that H3 was 10 μm.

[0216] Example 9

[0217] Example 9 was carried out in accordance with Example 1, except that H4 was 10 μm.

[0218] Example 10

[0219] Example 10 was carried out in accordance with Example 1, except that H3 was 4 μm and H4 was 4 μm.

[0220] Example 11

[0221] Example 11 was carried out in the same manner as Example 1, except that H3 was 16 μm and H4 was 16 μm.

[0222] Example 12

[0223] Example 12 was carried out in the same manner as Example 1, except that H4 was 15 μm.

[0224] Example 13

[0225] Example 13 was carried out in the same manner as Example 1, except that H4 was 9 μm.

[0226] Example 14

[0227] Example 14 was performed in accordance with Example 1, except that S3 was 0.4 mm. 2 S4 is 0.4mm. 2 .

[0228] Example 15

[0229] Example 15 was performed in the same manner as Example 1, except that S3 was 0.4 mm. 2 .

[0230] Example 16

[0231] Example 16 was carried out in accordance with Example 1, except that S3 was 0.3 mm. 2 S4 is 0.3mm. 2 .

[0232] Example 17

[0233] Example 17 was carried out in accordance with Example 1, except that S3 was 1.1 mm. 2 S4 is 1.1mm. 2 .

[0234] Example 18

[0235] Example 18 was carried out in accordance with Example 1, except that S3 was 0.3 mm. 2 .

[0236] Example 19

[0237] Example 19 was performed in accordance with Example 1, except that S3 was 1.1 mm. 2 .

[0238] Example 20

[0239] Example 20 was carried out in the same manner as Example 1, except that L1 was 2.1 mm.

[0240] Example 21

[0241] Example 21 is performed as in Example 1, except that L1 is 2mm.

[0242] Comparative Example 22

[0243] Example 22 was carried out in the same manner as Example 1, except that L1 was 8 mm.

[0244] Comparative Example 1

[0245] This comparative example is based on Example 1, except that the first and second concave-convex structures are not provided on the positive electrode sheet.

[0246] Table 1:

[0247]

[0248]

[0249]

[0250]

[0251] The relevant performance of the batteries in the above embodiments and comparative examples was tested, and the test results are recorded in Table 2. The test methods are as follows:

[0252] 1. Lithium plating status of the battery cell

[0253] The batteries obtained in the above examples and comparative examples were charged at 25°C with a constant current of 1.2C to 4.3V, then charged at 0.7C to 4.45V, then charged at a constant voltage of 0.05C, left to stand for 10 minutes, discharged at 0.5C to 3V, left to stand for 10 minutes, discharged at 0.5C to 3V, left to stand for 10 minutes, and so on. This charge-discharge cycle was repeated 800 times. The batteries were then disassembled in a dry room to observe the lithium plating in the cells.

[0254] 2. Situation where the positive electrode plate is crushed

[0255] After the positive electrode sheet is embossed, the extent of crushing is observed using a 3D microscope (see [link to document on crushing positive electrode sheet]). Figure 13 See also: when the positive electrode is not crushed. Figure 14 ).

[0256] Table 2:

[0257] Lithium plating in battery cells The positive electrode sheet was crushed Example 1 No lithium plating Not crushed Example 2 No lithium plating Not crushed Example 3 No lithium plating Not crushed Example 4 No lithium plating Not crushed Example 5 Lithium plating Not crushed Example 6 No lithium plating Not crushed Example 7 No lithium plating Not crushed Example 8 No lithium plating Not crushed Example 9 No lithium plating Not crushed Example 10 No lithium plating Not crushed Example 11 No lithium plating crushed Example 12 No lithium plating Not crushed Example 13 No lithium plating Not crushed Example 14 No lithium plating Not crushed Example 15 No lithium plating Not crushed Example 16 No lithium plating Not crushed Example 17 No lithium plating Not crushed Example 18 No lithium plating Not crushed Example 19 No lithium plating Not crushed Example 20 No lithium plating Not crushed Example 21 Lithium plating Not crushed Example 22 Lithium plating Not crushed Comparative Example 1 Lithium plating /

[0258] As shown in Tables 1 and 2, when the positive electrode is provided with the first concave-convex structure and the second concave-convex structure, there is no lithium plating and the interface deterioration can be suppressed.

[0259] According to Tables 1 and 2, when the ratio of the height of the second convex portion 10b1 to the height H3 of the arc-shaped convex portion 10e1 is greater than or equal to 1 / 5 and less than or equal to 3 / 5, lithium deposition does not occur, interface deterioration can be suppressed, and the positive electrode sheet is not crushed. When the ratio of the height of the second convex portion 10b1 to the height of the flat convex portion 10d1 is greater than or equal to 1 / 5 and less than or equal to 3 / 5, lithium deposition does not occur, interface deterioration can be suppressed, and the positive electrode sheet is not crushed.

[0260] According to Tables 1 and 2, when the ratio of the height of the arc region protrusion 10e1 to the height of the straight region protrusion 10d1 is greater than 1 and less than or equal to 1.5, there is no lithium plating, the interface deterioration can be suppressed, and the positive electrode sheet is not crushed.

[0261] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model 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 utility model.

Claims

1. A battery cell, characterized in that, The battery cell includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode; the positive electrode, the negative electrode, and the separator are stacked and wound together to form the battery cell. The positive electrode includes a first current collector and a first active material layer located on both sides of the first current collector; The positive electrode includes a first region in which the first active material layer is disposed on both sides of the first current collector, and a second region in which the first active material layer is disposed only on one side of the first current collector. The second region is located on the side of the first region away from the interior of the battery cell; The second region includes the portion corresponding to the outermost ring of the positive electrode sheet; The positive electrode sheet has a plurality of spaced-apart first concave-convex structures formed on the first region. The first concave-convex structures form a first protrusion on one side of the positive electrode sheet in the thickness direction and a first concave structure on the other side of the positive electrode sheet in the thickness direction. The positive electrode sheet has a plurality of spaced second concave-convex structures formed on the second region. The second concave-convex structures form a second protrusion on one side of the positive electrode sheet in the thickness direction and a second concave structure forms a second recess on the other side of the positive electrode sheet in the thickness direction. The distance between two adjacent first protrusions is D1, and the distance between two adjacent second protrusions is D2, wherein D2 > D1.

2. The battery cell according to claim 1, characterized in that, The ratio of D2 to D1 is greater than 1 and less than or equal to 1.5; and / or, The D1 is greater than or equal to 1 mm and less than or equal to 8 mm; and / or, The D2 is greater than or equal to 3 mm and less than or equal to 10 mm.

3. The battery cell according to claim 1, characterized in that, In the thickness direction of the positive electrode sheet, the height of the second protrusion is H2, and the height of the first protrusion is H1, wherein H2≤H1.

4. The battery cell according to claim 3, characterized in that, The ratio of H2 to H1 is greater than or equal to 1 / 5 and less than or equal to 3 / 5; and / or, H1 is greater than or equal to 3 μm and less than or equal to 100 μm; and / or, The H2 is greater than or equal to 3 μm and less than or equal to 35 μm.

5. The battery cell according to claim 1, characterized in that, In the thickness direction of the positive electrode sheet, the area of ​​the projection of the first protrusion is S1, and the area of ​​the projection of the second protrusion is S2, wherein S2 > S1.

6. The battery cell according to claim 5, characterized in that, The ratio of S2 to S1 is greater than or equal to 1.2 and less than or equal to 3; and / or, The S1 is greater than or equal to 0.1 mm 2 and less than or equal to 7mm 2 ; and / or, The S2 is greater than or equal to 0.5mm 2 and less than or equal to 10mm 2 .

7. The battery cell according to claim 1, characterized in that, In the winding direction of the positive electrode sheet, the distance between adjacent first protrusions and second protrusions is greater than or equal to 2 mm and less than or equal to 1 mm.

8. The battery cell according to claim 7, characterized in that, In the winding direction of the positive electrode sheet, the boundary between the first region and the second region is the first boundary; The distance between the first protrusion and the first boundary is greater than or equal to 1 mm; and / or, The distance between the second protrusion and the first boundary is greater than or equal to 1 mm.

9. The battery cell according to claim 1, characterized in that, In the width direction of the positive electrode sheet, a first clearance portion is provided on at least one edge of the first region, and a second clearance portion is provided on at least one edge of the second region.

10. The battery cell according to any one of claims 1-9, characterized in that, In the winding direction of the positive electrode sheet, the positive electrode sheet includes alternating straight areas and arc areas; The first convex portion located in the arc region is an arc region convex portion, and the first convex portion located in the flat region is a flat region convex portion. In the thickness direction of the positive electrode sheet, the height of the arc region convex portion is H3, and the height of the flat region convex portion is H4, wherein H3 > H4.

11. The battery cell according to claim 10, characterized in that, The ratio of H3 to H4 is greater than 1 and less than or equal to 1.5; and / or, The H3 is greater than or equal to 5 μm and less than or equal to 100 μm; and / or, The H4 is greater than or equal to 3 μm and less than or equal to 80 μm.

12. The battery cell according to claim 10, characterized in that, The distance between two adjacent arc-shaped protrusions is D6, and the distance between two adjacent straight protrusions is D7, wherein D6≤D7.

13. The battery cell according to claim 12, characterized in that, The ratio of D6 to D7 is greater than or equal to 0.5 and less than or equal to 1; and / or, The D6 is greater than or equal to 1 mm and less than or equal to 5 mm; and / or, The D7 is greater than or equal to 2 mm and less than or equal to 8 mm.

14. The battery cell according to claim 10, characterized in that, In the thickness direction of the positive electrode sheet, the projected area of ​​the arc-shaped protrusion is S3, and the projected area of ​​the flat protrusion is S4, where S3≤S4.

15. The battery cell according to claim 14, characterized in that, The ratio of S3 to S4 is greater than or equal to 0.4 and less than or equal to 1; and / or, The S3 is greater than or equal to 0.1 mm 2 and less than or equal to 4mm 2 ; and / or, The S4 is greater than or equal to 0.2mm 2 and less than or equal to 7mm 2 .

16. The battery cell according to claim 10, characterized in that, In the thickness direction of the positive electrode sheet, the perimeter of the projection of the arc-shaped protrusion is L1, and the perimeter of the projection of the straight protrusion is L2, where L1≤L2.

17. The battery cell according to claim 16, characterized in that, The ratio of L1 to L2 is greater than or equal to 0.3 and less than or equal to 1; and / or, The L1 is greater than or equal to 2 mm and less than or equal to 7 mm; and / or, The L2 is greater than or equal to 2 mm and less than or equal to 10 mm.

18. A battery, characterized in that, Includes the battery cell as described in any one of claims 1-17.

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