Winding core and battery

Abstract

The utility model provides a kind of roll core and battery, at least one first embossed area is equipped on the positive sheet of arc region, each first embossed area includes at least one first embossed groove;At least one second embossed area is equipped on the negative sheet of arc region, each second embossed area includes at least one second embossed groove;Each first embossed groove is correspondingly arranged with a second embossed groove;The opening direction of each first embossed groove is same with the opening direction of its corresponding second embossed groove, and electrolyte flow channel exists between the two, improve the accuracy of the sheet embossing of roll core arc region, can ensure that electrolyte flow channel exists between each first embossed groove and its corresponding second embossed groove, can realize increasing electrolyte flow channel, avoid limiting the flowability of electrolyte, effectively improve the lithium precipitation situation of roll core arc region, maintain roll core energy density.

Description

Technical Field

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

[0002] Due to structural limitations of the wound core, the electrolyte wettability in the arc-shaped area is poor. In fast-charging systems, electrolyte consumption is accelerated, leading to lithium plating or other side reactions in the arc-shaped area. While improving electrolyte wettability in the arc-shaped area is typically achieved by increasing separator thickness, reducing formation pressure, and increasing electrolyte wetting time, this increases the overall thickness of the wound core, reducing its energy density. Electrode embossing is a commonly used process technology. By embossing the electrodes in the arc-shaped area of ​​the wound core to a certain extent, the electrolyte retention in this area can be increased, and more electrolyte flow channels can be provided. However, the precision of current electrode embossing techniques in the arc-shaped area of ​​wound cores is poor, which may worsen lithium plating in the arc-shaped area. Summary of the Invention

[0003] This invention provides a winding core and a battery to solve the problem that the poor precision of electrode embossing in the arc region of existing winding cores may worsen the problem of lithium plating in the arc region.

[0004] A wound core includes a positive electrode sheet, a separator, and a negative electrode sheet; the positive electrode sheet, the separator, and the negative electrode sheet are formed into a wound core by a winding process, and the wound core includes an arc region and a straight region;

[0005] At least one first embossed area is provided on the positive electrode sheet located in the arc region, and each first embossed area includes at least one first embossed groove.

[0006] At least one second embossed area is provided on the negative electrode sheet located in the arc region, and each second embossed area includes at least one second embossed groove.

[0007] Each of the first embossing grooves is provided in correspondence with one of the second embossing grooves;

[0008] The opening orientation of each of the first embossing grooves is the same as the opening orientation of the corresponding second embossing groove, and there is an electrolyte flow channel between them.

[0009] Preferably, the first embossing groove and the second embossing groove are arc-shaped embossing grooves, and the center lines of the corresponding first embossing groove and the second embossing groove coincide.

[0010] Preferably, the first embossing groove and the second embossing groove are arc-shaped embossing grooves.

[0011] Preferably, the ratio of the area of ​​each of the first embossing grooves to the area of ​​its corresponding second embossing groove is greater than or equal to 0 and less than 1.

[0012] Preferably, the openings of the first embossing groove and the second embossing groove both face the inside or outside of the core.

[0013] Preferably, the length of each first embossed area is 2-10 mm, and the length of the first embossed area gradually increases from the inner layer to the outer layer of the core;

[0014] The length of each second embossed area is 2-10 mm, and the length of the second embossed area gradually increases from the inner layer to the outer layer of the core.

[0015] Preferably, the distance between two adjacent first embossing grooves is 0.5-2mm;

[0016] The distance between two adjacent second embossing grooves is 0.5-2mm.

[0017] Preferably, the width of each first embossing groove is 0.4-2.0 mm, and the depth of each first embossing groove is 20-100 μm;

[0018] The width of each second embossing groove is 0.4-2.0 mm, and the depth of each second embossing groove is 20-100 μm.

[0019] Preferably, the total area of ​​all the first embossed areas and the second embossed areas accounts for 10%-40% of the total area of ​​the positive electrode and the negative electrode in the arc region of the core.

[0020] A battery, comprising a battery casing and the said winding core;

[0021] The winding core is installed inside the battery casing.

[0022] This embodiment of the invention provides a core in which each first embossing groove is correspondingly arranged with a second embossing groove. The opening orientation of each first embossing groove is the same as the opening orientation of its corresponding second embossing groove, and there is an electrolyte flow channel between them. The width of the electrolyte flow channel, i.e., the distance between the positive electrode and the negative electrode, is greater than the thickness of the separator. In other words, there is an electrolyte flow channel between the positive electrode and the separator and / or between the separator and the negative electrode. This arrangement improves the accuracy of electrode embossing in the arc region of the core and ensures that there is an electrolyte flow channel between each first embossing groove and its corresponding second embossing groove. This can increase the electrolyte flow channel, avoid restricting the fluidity of the electrolyte, effectively improve the lithium plating situation in the arc region of the core, and maintain the core energy density. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a cross-sectional view of the core in one embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the embossing of the positive and negative electrode sheets in the arc region in one embodiment of this utility model;

[0026] Figure 3 This is a schematic diagram showing the corresponding positive and negative electrode plates in a conventional arc region in one embodiment of this utility model;

[0027] Figure 4 This is a schematic diagram of the positive and negative electrode sheets corresponding to the first embossed arc region in one embodiment of this utility model;

[0028] Figure 5 This is a schematic diagram of the corresponding positive and negative electrode sheets in the second embossed arc region of an embodiment of this utility model.

[0029] Among them, 1. positive electrode plate; 2. separator; 3. negative electrode plate; 4. first embossing groove; 5. second embossing groove. Detailed Implementation

[0030] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0031] In the description of this application, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0032] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0033] This utility model embodiment provides a winding core, as shown in the reference. Figure 1 , Figure 2 and Figure 3 The core includes a positive electrode 1, a separator 2, and a negative electrode 3; the core includes an arc region and a straight region; the positive electrode 1 located in the arc region is provided with at least one first embossed region, each first embossed region including at least one first embossed groove 4; the negative electrode 3 located in the arc region adjacent to the first embossed region is provided with at least one second embossed region, each second embossed region including at least one second embossed groove 5; each first embossed groove 4 is correspondingly provided with a second embossed groove 5; the opening orientation of each first embossed groove 4 is the same as the opening orientation of its corresponding second embossed groove 5, and there is an electrolyte flow channel between them.

[0034] As an example, the core includes a positive electrode 1, a negative electrode 3, and a separator 2; the positive electrode 1, separator 2, and negative electrode 3 are formed into a core by a winding process, and the core includes an arc-shaped region and a straight region. At least one first embossed region is provided on the positive electrode 1 located in the arc-shaped region, each first embossed region including at least one first embossed groove 4, which can provide a suitable channel for electrolyte flow and improve the situation of lithium deposition at the arc. At least one second embossed region is provided on the negative electrode 3 located in the arc-shaped region, each second embossed region including at least one second embossed groove 5, which can also provide a suitable channel for electrolyte flow and improve the situation of lithium deposition at the arc. Each first embossing groove 4 is correspondingly set with a second embossing groove 5. The opening direction of each first embossing groove 4 is the same as the opening direction of its corresponding second embossing groove 5, and there is an electrolyte flow channel between them. The width of the electrolyte flow channel, i.e., the distance between the positive electrode 1 and the negative electrode 3, is greater than the thickness of the separator 2. In other words, there is an electrolyte flow channel between the positive electrode 1 and the separator 2 and / or between the separator 2 and the negative electrode 3. This setting improves the accuracy of electrode embossing in the arc area of ​​the core and ensures that there is an electrolyte flow channel between each first embossing groove 4 and its corresponding second embossing groove 5. This can increase the electrolyte flow channel, avoid restricting the fluidity of the electrolyte, effectively improve the lithium plating situation in the arc area of ​​the core, and maintain the core energy density.

[0035] In one embodiment, reference is made to Figure 1 , Figure 2 and Figure 3 The first embossing groove 4 and the second embossing groove 5 are arc-shaped embossing grooves, and the center lines of the corresponding first embossing groove 4 and the second embossing groove 5 coincide.

[0036] As an example, making the first embossing groove 4 and the second embossing groove 5 into arc-shaped embossing grooves can also avoid damage to the electrode sheet. The center lines of the corresponding first embossing groove 4 and the second embossing groove 5 coincide, thus ensuring that each first embossing groove 4 is correspondingly set with a second embossing groove 5. The opening direction of each first embossing groove 4 is the same as the opening direction of its corresponding second embossing groove 5, and there is an electrolyte flow channel between them. That is to say, there is a flow channel between the positive electrode sheet 1 and the separator 2 and / or between the separator 2 and the negative electrode sheet 3, which improves the accuracy of electrode embossing in the arc area of ​​the core.

[0037] In one embodiment, reference is made to Figure 1 , Figure 2 and Figure 3 The first embossing groove 4 and the second embossing groove 5 are arc-shaped embossing grooves.

[0038] As an example, the first embossing groove 4 and the second embossing groove 5 are arc-shaped embossing grooves, which can avoid damage to the electrode sheet.

[0039] In one embodiment, reference is made to Figure 5 The ratio of the area of ​​each first embossing groove 4 to the area of ​​its corresponding second embossing groove 5 is greater than or equal to 0 and less than 1.

[0040] As an example, when K is greater than or equal to 1, meaning the area of ​​the first embossing groove 4 is greater than or equal to the area of ​​its corresponding second embossing groove 5, the gap between them, the height of which is the distance between the positive electrode 1 and the negative electrode 3, is equal to the thickness of the separator 2. This means there are no flow channels between the positive electrode 1 and the separator 2, or between the separator 2 and the negative electrode 3, restricting the fluidity of the electrolyte and worsening the arc-shaped lithium plating. Therefore, it is necessary to limit the ratio K of the area of ​​each first embossing groove 4 to the area of ​​its corresponding second embossing groove 5, ensuring that K is greater than or equal to 0 and less than 1. This design improves the accuracy of electrode embossing in the arc-shaped region of the core, ensuring that there are flow channels between each first embossing groove 4 and its corresponding second embossing groove 5. This increases the fluidity of the electrolyte, avoids restricting its flow, effectively improves the arc-shaped lithium plating situation, and maintains the core's energy density.

[0041] The area of ​​the embossed groove is calculated as follows: the radius of the simulated circle of the embossed groove is R, the width of the embossed groove is L, the depth of the embossed groove is H, and the arc angle corresponding to the embossed groove is θ; within the sector corresponding to the arc embossed groove... ; ;

[0042] The area of ​​the sector corresponding to the arc-shaped pressure groove is S_sector = ;

[0043] The area of ​​the embossed groove = S_fan - .

[0044] The following are the parameters for the example:

[0045] Example 1: Refer to Figure 5 The length of the first embossed area is 6 mm, the width of the first embossed groove 4 is 1.0 mm, the depth of the first embossed groove 4 is 40 μm, the distance between two adjacent first embossed grooves 4 is 1.0 mm, and the area of ​​the first embossed groove 4 is 0.027. The second embossed area has a length of 6 mm, a width of 1.2 mm, a depth of 50 μm, a spacing of 0.6 mm between two adjacent second embossed grooves, and an area of ​​0.040 mm. The ratio of the area of ​​the first embossing groove 4 to the area of ​​its corresponding second embossing groove 5 is 0.68.

[0046] Example 2: Refer to Figure 5 The length of the first embossed area is 6 mm, the width of the first embossed groove 4 is 1.0 mm, the depth of the first embossed groove 4 is 40 μm, the distance between two adjacent first embossed grooves 4 is 1.0 mm, and the area of ​​the first embossed groove 4 is 0.027. The second embossed area has a length of 6 mm, a width of 1.3 mm, a depth of 60 μm, a spacing of 0.4 mm between two adjacent second embossed grooves, and an area of ​​0.052 mm. The ratio of the area of ​​the first embossing groove 4 to the area of ​​its corresponding second embossing groove 5 is 0.52.

[0047] Example 3: Reference Figure 5 The length of the first embossed area is 6 mm, the width of the first embossed groove 4 is 0.8 mm, the depth of the first embossed groove 4 is 35 μm, the distance between two adjacent first embossed grooves 4 is 1.4 mm, and the area of ​​the first embossed groove 4 is 0.019 mm. The second embossed area has a length of 6 mm, a width of 1.2 mm, a depth of 50 μm, a spacing of 1.0 mm between two adjacent second embossed grooves, and an area of ​​0.040 mm. The ratio of the area of ​​the first embossing groove 4 to the area of ​​its corresponding second embossing groove 5 is 0.48.

[0048] Example 4: Reference Figure 5 The length of the first embossed area is 6 mm, the width of the first embossed groove 4 is 1.0 mm, the depth of the first embossed groove 4 is 40 μm, the distance between two adjacent first embossed grooves 4 is 1.0 mm, and the area of ​​the first embossed groove 4 is 0.027. The second embossed area has a length of 6 mm, a width of 1.1 mm, a depth of 45 μm, a spacing of 0.8 mm between two adjacent second embossed grooves, and an area of ​​0.033 mm. The ratio of the area of ​​the first embossing groove 4 to the area of ​​its corresponding second embossing groove 5 is 0.82.

[0049] Example 5: Refer to Figure 5 The length of the first embossed area is 0 mm, the width of the first embossed groove 4 is 0 mm, the depth of the first embossed groove 4 is 0 μm, the distance between two adjacent first embossed grooves 4 is 0 mm, and the area of ​​the first embossed groove 4 is 0. The second embossed area has a length of 6 mm, a width of 1.2 mm, a depth of 50 μm, a spacing of 0.6 mm between two adjacent second embossed grooves, and an area of ​​0.040 mm. The ratio of the area of ​​the first embossing groove 4 to the area of ​​its corresponding second embossing groove 5 is 0.

[0050] Comparative Example 1: Reference Figure 3 No embossing;

[0051] Comparative Example 2: Reference Figure 4 The length of the first embossed area is 6 mm, the width of the first embossed groove 4 is 1.0 mm, the depth of the first embossed groove 4 is 40 μm, the distance between two adjacent first embossed grooves 4 is 1.0 mm, and the area of ​​the first embossed groove 4 is 0.027. The second embossed area has a length of 6 mm, a width of 0.8 mm, a depth of 40 μm, a spacing of 1.0 mm between two adjacent second embossed grooves, and an area of ​​0.027 mm. The ratio of the area of ​​the first embossing groove 4 to the area of ​​its corresponding second embossing groove 5 is 1.0.

[0052] Comparative Example 3: Reference Figure 4 The length of the first embossed area is 6 mm, the width of the first embossed groove 4 is 1.0 mm, the depth of the first embossed groove 4 is 40 μm, the distance between two adjacent first embossed grooves 4 is 1.0 mm, and the area of ​​the first embossed groove 4 is 0.027. The second embossed area has a length of 6 mm, a width of 0.8 mm, a depth of 30 μm, a spacing of 1.6 mm between two adjacent second embossed grooves, and an area of ​​0.016 mm. The ratio of the area of ​​the first embossing groove 4 to the area of ​​its corresponding second embossing groove 5 is 1.69.

[0053] Comparative Example 4: Reference Figure 4 The length of the first embossed area is 6 mm, the width of the first embossed groove 4 is 1.2 mm, the depth of the first embossed groove 4 is 50 μm, the distance between two adjacent first embossed grooves 4 is 0.6 mm, and the area of ​​the first embossed groove 4 is 0.040 mm. The second embossed area has a length of 6 mm, a width of 1.0 mm, a depth of 40 μm, a spacing of 1.0 mm between two adjacent second embossed grooves, and an area of ​​0.027 mm. The ratio of the area of ​​the first embossing groove 4 to the area of ​​its corresponding second embossing groove 5 is 1.48.

[0054] The battery cell is charged at 3C constant current and constant voltage to 4.5V, cut off at 0.05C, and discharged at 0.5C. After 1000 cycles, the battery is disassembled to check the lithium plating on the electrodes, which is divided into no lithium plating, slight lithium plating, moderate lithium plating, and severe lithium plating.

[0055] Comparison of battery cell test performance:

[0056] Example 1: Energy density of 750.2 Wh / L, cycle count of 1000, no lithium deposition at the arc;

[0057] Example 2: Energy density of 750.3 Wh / L, cycle count of 1000, no lithium deposition at the arc;

[0058] Example 3: Energy density was 749.8 Wh / L, cycle count was 1000, and there was no lithium deposition at the arc.

[0059] Example 4: Energy density of 750.3 Wh / L, cycle count of 1000, no lithium deposition at the arc;

[0060] Example 5: Energy density was 749.7 Wh / L, cycle count was 1000, and there was no lithium deposition at the arc.

[0061] Comparative Example 1: Energy density of 750.0 Wh / L, cycle count of 1000, lithium deposition at the arc is severe;

[0062] Comparative Example 2: Energy density was 750.4 Wh / L, cycle count was 1000, and lithium deposition at the arc was slight.

[0063] Comparative Example 3: Energy density was 750.1 Wh / L, number of cycles was 1000, and lithium deposition at the arc was moderate.

[0064] Comparative Example 4: Energy density was 750.1 Wh / L, number of cycles was 1000, and lithium deposition in the arc was moderate.

[0065] In one embodiment, the openings of the first embossing groove 4 and the second embossing groove 5 both face the inner or outer side of the core.

[0066] As an example, the opening orientation of the embossing groove can take two forms depending on actual needs; the first is that the openings of the first embossing groove 4 and the second embossing groove 5 both face the inside of the core; the second is that the openings of the first embossing groove 4 and the second embossing groove 5 both face the outside of the core. This arrangement ensures that there is a flow channel between each first embossing groove 4 and its corresponding second embossing groove 5, which can increase the flow channel of the electrolyte, avoid restricting the fluidity of the electrolyte, and effectively improve the lithium plating situation in the arc area of ​​the core.

[0067] In one embodiment, the length of each first embossed area is 2-10 mm, and the length of the first embossed area gradually increases from the inner layer to the outer layer of the core in the radial direction of the arc area; the length of each second embossed area is 2-10 mm, and the length of the second embossed area gradually increases from the inner layer to the outer layer of the core.

[0068] As an example, when embossing the positive electrode 1, if the first embossing area is too small, it is close to no embossing and has no obvious effect; if the first embossing area is too long, it will extend into the straight area of ​​the core, which will increase the core thickness and reduce the battery energy density. Therefore, the first embossing area is limited, and the length of each first embossing area is 2-10mm. From the inner layer to the outer layer of the core, or in other words, in the radial direction of the arc area, the length of the first embossing area gradually increases from the inside to the outside. This setting can ensure that the positive electrode 1 has an embossing effect, provide a suitable channel for electrolyte flow, and improve the situation of lithium plating in the arc. When embossing the negative electrode sheet 3, if the second embossing area is too small, it is close to no embossing and has no obvious effect; if the second embossing area is too long, it will extend into the straight area of ​​the core, which will increase the core thickness and reduce the battery energy density. Therefore, the second embossing area is limited, and the length of each second embossing area is 2-10mm. From the inner layer to the outer layer of the core, or in other words, in the radial direction of the arc area, the length of the second embossing area gradually increases from the inside to the outside. This setting can ensure that the negative electrode sheet 3 has an embossing effect, provide a suitable channel for electrolyte flow, and improve the situation of lithium plating in the arc.

[0069] In one embodiment, reference is made to Figure 2 , Figure 3 , Figure 4 and Figure 5 The distance between two adjacent first embossing grooves 4 is 0.5-2mm; the distance between two adjacent second embossing grooves 5 is 0.5-2mm.

[0070] As an example, when embossing the positive electrode 1, if the spacing between two adjacent first embossing grooves 4 is too small, it cannot form a single slot for storing electrolyte, resulting in no significant effect; if the spacing between two adjacent first embossing grooves 4 is too large, the electrolyte storage is limited, resulting in no significant effect. Therefore, the spacing between two adjacent first embossing grooves 4 is limited to 0.5-2mm. This setting ensures that a single slot for storing electrolyte can be formed on the positive electrode 1, avoiding limited electrolyte storage and thus improving the lithium plating problem in the arc area of ​​the core. When embossing the negative electrode 3, if the spacing between two adjacent second embossing grooves 5 is too small, a single groove cannot be formed to store electrolyte, resulting in no significant effect; if the spacing between two adjacent second embossing grooves 5 is too large, the electrolyte storage is limited, also resulting in no significant effect. Therefore, the spacing between two adjacent second embossing grooves 5 is limited to 0.5-2mm. This setting ensures that a single groove can be formed on the negative electrode 3 to store electrolyte, avoiding limited electrolyte storage and thus improving the lithium plating problem in the arc area of ​​the core.

[0071] In one embodiment, reference is made to Figure 2 , Figure 3 , Figure 4 and Figure 5 The width of each first embossing groove 4 is 0.4-2.0 mm, and the depth of each first embossing groove 4 is 20-100 μm; the width of each second embossing groove 5 is 0.4-2.0 mm, and the depth of each second embossing groove 5 is 20-100 μm.

[0072] As an example, if the width or depth of the embossing groove is too large or too small, there are fewer channels for electrolyte flow, which cannot improve the electrolyte retention in the arc and thus cannot improve the lithium plating in the arc. If the width or depth of the embossing groove is too small or too large, the electrolyte flow channels are too narrow or too deep, restricting the fluidity of the electrolyte and failing to improve the lithium plating in the arc. Therefore, it is necessary to limit the depth and width of the first embossing groove 4 and the second embossing groove 5, so that the width of each first embossing groove 4 is 0.4-2.0 mm and the depth of each first embossing groove 4 is 20-100 μm; the width of each second embossing groove 5 is 0.4-2.0 mm and the depth of each second embossing groove 5 is 20-100 μm. This design can ensure that there is a flow channel between each first embossing groove 4 and its corresponding second embossing groove 5, which can increase the flow channel of the electrolyte, avoid restricting the fluidity of the electrolyte, effectively improve the lithium plating in the arc region of the core, and maintain the core energy density.

[0073] In one embodiment, the total area of ​​all the first embossed areas and the second embossed areas accounts for 10%-40% of the total area of ​​the positive electrode 1 and the negative electrode 3 in the arc region of the core.

[0074] As an example, when the total area of ​​all the first and second embossed areas accounts for less than 10% of the total area of ​​the positive electrode 1 and negative electrode 3 in the arc region of the core, there is no effect. When the total area of ​​all the first and second embossed areas accounts for more than 40% of the total area of ​​the positive electrode 1 and negative electrode 3 in the arc region of the core, it is easy to cause electrode damage and strip breakage. Therefore, it is necessary to limit the proportion of the total area of ​​all the first and second embossed areas in the total area of ​​the positive electrode 1 and negative electrode 3 in the arc region of the core. The total area of ​​all the first and second embossed areas in the total area of ​​the positive electrode 1 and negative electrode 3 in the arc region of the core should be between 10% and 40%. Within this range, more electrolyte transport channels can be provided, improving the problem of lithium plating in the arc region and extending the cycle life of the cell.

[0075] In one embodiment, reference is made to Figure 1 and Figure 2During the core manufacturing process, the positive electrode 1, separator 2, and negative electrode 3 are arranged alternately, with separator 2 located between the positive electrode 1 and the negative electrode 3. In the winding direction, the length of separator 2 is greater than the length of negative electrode 3. The longer separator 2 can better wrap the electrode sheet, making the winding process smoother and reducing problems such as misalignment and wrinkles of the electrode sheet during the winding process, thereby improving the consistency and production efficiency of the battery. The length of negative electrode 3 is greater than the length of positive electrode 1, which can increase the effective area of ​​the negative electrode and the lithium-ion insertion sites, thereby improving the charge and discharge efficiency and cycle life of the battery.

[0076] This utility model provides a battery, including a battery casing and a winding core; the winding core is installed inside the battery casing.

[0077] As an example, the battery includes a battery casing and a core. During installation, the core is installed inside the battery casing. The core includes a positive electrode 1, a negative electrode 3, and a separator 2. The positive electrode 1, separator 2, and negative electrode 3 are formed into a core through a winding process. The core includes arc-shaped regions and straight regions. At least one first embossed region is provided on the positive electrode 1 located in the arc-shaped region. Each first embossed region includes at least one first embossed groove 4, which can provide a suitable channel for electrolyte flow and improve the situation of lithium deposition at the arc. At least one second embossed region is provided on the negative electrode 3 located in the arc-shaped region. Each second embossed region includes at least one second embossed groove 5, which can also provide a suitable channel for electrolyte flow and improve the situation of lithium deposition at the arc. Each first embossing groove 4 is correspondingly set with a second embossing groove 5. The opening direction of each first embossing groove 4 is the same as the opening direction of its corresponding second embossing groove 5, and there is an electrolyte flow channel between them. The width of the electrolyte flow channel, i.e., the distance between the positive electrode 1 and the negative electrode 3, is greater than the thickness of the separator 2. In other words, there is an electrolyte flow channel between the positive electrode 1 and the separator 2 and / or between the separator 2 and the negative electrode 3. This setting improves the accuracy of electrode embossing in the arc area of ​​the core and ensures that there is an electrolyte flow channel between each first embossing groove 4 and its corresponding second embossing groove 5. This can increase the electrolyte flow channel, avoid restricting the fluidity of the electrolyte, effectively improve the lithium plating situation in the arc area of ​​the core, and maintain the core energy density.

[0078] The above-described 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A type of winding core, characterized in that, It includes a positive electrode sheet, a separator, and a negative electrode sheet; the wound core includes an arc-shaped region and a straight region; The positive electrode sheet located in the arc region is provided with at least one first embossed region, and each first embossed region includes at least one first embossed groove; The negative electrode sheet located in the arc region adjacent to the first embossed region is provided with at least one second embossed region, and each second embossed region includes at least one second embossed groove; Each of the first embossing grooves is provided in correspondence with one of the second embossing grooves; The opening orientation of each of the first embossing grooves is the same as the opening orientation of the corresponding second embossing groove, and there is an electrolyte flow channel between them.

2. The winding core according to claim 1, characterized in that, The first embossing groove and the second embossing groove are arc-shaped embossing grooves, and the center lines of the corresponding first embossing groove and the second embossing groove coincide.

3. The winding core according to claim 2, characterized in that, The first embossing groove and the second embossing groove are arc-shaped embossing grooves.

4. The winding core according to claim 3, characterized in that, The ratio of the area of ​​each of the first embossed grooves to the area of ​​its corresponding second embossed groove is greater than or equal to 0 and less than 1.

5. The winding core according to any one of claims 1-4, characterized in that, The openings of the first embossing groove and the second embossing groove both face the inside or outside of the core.

6. The winding core according to any one of claims 1-4, characterized in that, The length of each of the first embossed areas is 2-10 mm, and the length of the first embossed areas gradually increases from the inner layer to the outer layer of the core. The length of each second embossed area is 2-10 mm, and the length of the second embossed area gradually increases from the inner layer to the outer layer of the core.

7. The winding core according to any one of claims 1-4, characterized in that, The distance between two adjacent first embossing grooves is 0.5-2mm; The distance between two adjacent second embossing grooves is 0.5-2mm.

8. The winding core according to any one of claims 1-4, characterized in that, The width of each first embossing groove is 0.4-2.0 mm, and the depth of each first embossing groove is 20-100 μm; The width of each second embossing groove is 0.4-2.0 mm, and the depth of each second embossing groove is 20-100 μm.

9. The winding core according to any one of claims 1-4, characterized in that, The total area of ​​all the first embossed areas and the second embossed areas accounts for 10%-40% of the total area of ​​the positive electrode and the negative electrode in the arc region of the core.

10. A battery, characterized in that, Includes a battery casing and a winding core as described in any one of claims 1-9; The winding core is installed inside the battery casing.

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