Electrode plate with embossing and cylindrical battery using same

Abstract

The utility model discloses an embossed electrode plate and a cylindrical battery using the same, and relates to the technical field of battery structures, the embossed electrode plate comprises an electrode plate, and the electrode plate is of a winding structure; at least three discontinuous embossed areas are distributed on the surface of the pole piece in the winding direction of the pole piece, the multiple embossed areas are all located on the surface of the same side of the pole piece, and in the embossed areas, the surface of the pole piece is provided with multiple arrayed recesses. According to the electrode plate with the embossed patterns and the cylindrical battery using the electrode plate, the lithium precipitation degree in the battery circulation process can be reduced, and the cycle life of the battery is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of battery structures, in particular to an electrode sheet with embossing and a cylindrical battery using the same. Background Art

[0002] Traditional cylindrical batteries, particularly lithium-ion cylindrical batteries, still face the problem of lithium deposition after cell cycling due to manufacturing process limitations. This phenomenon occurs after repeated charge and discharge cycles. Typically, lithium deposition begins after 300 cycles, shortening the battery's cycle life.

[0003] When charging a cylindrical lithium-ion battery, if lithium ions cannot be quickly embedded in the negative electrode, they will precipitate on the negative electrode's surface to form solid metallic lithium. This reaction is irreversible. The precipitation of lithium ions into metallic lithium reduces the battery's energy density and charge / discharge efficiency, leading to a decline in battery performance and severely impacting its cycle life. Utility Model Content

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an embossed electrode sheet that can reduce the degree of lithium deposition during battery cycling and extend the cycle life of the battery.

[0005] The utility model also provides a cylindrical battery.

[0006] According to the first embodiment of the present invention, the electrode sheet with embossing comprises: an electrode sheet having a winding structure;

[0007] The embossed area has at least three non-continuous embossed areas distributed on the surface of the pole piece along the winding direction of the pole piece, and multiple embossed areas are located on the same side surface of the pole piece. In the embossed area, the surface of the pole piece is provided with multiple arrays of depressions.

[0008] The embossed electrode sheet according to the embodiment of the present invention has at least the following beneficial effects: the embossed area is provided with multiple depressions, which further improves the electrolyte conductivity of the electrode surface, and the electrolyte infiltrates the electrode more fully, which can greatly improve the cycle life of the battery; by adjusting the number and position distribution of the embossed areas by design, the electrode powder loss and capacity loss can also be avoided.

[0009] According to some embodiments of the present invention, the area of ​​the pole piece close to the winding center is the inner ring, the area of ​​the pole piece away from the winding center is the outer ring, and the multiple embossed areas are distributed in the outer ring, the inner ring, and the area between the outer ring and the inner ring.

[0010] According to some embodiments of the present invention, there are five embossed areas distributed on the surface of the pole piece, wherein the outer ring has two embossed areas, the area between the outer ring and the inner ring has one embossed area, and the inner ring has two embossed areas.

[0011] According to some embodiments of the present invention, the depths of the depressions in different embossed areas are different.

[0012] According to some embodiments of the present invention, the thickness of the pole piece is a, and the depth of the recess in the embossed area is 0.2a to 0.5a.

[0013] According to some embodiments of the present invention, the winding direction of the pole piece is the length direction of the pole piece, and the length of the embossed area is 2πd, where d is the diameter of the winding structure of the pole piece.

[0014] According to some embodiments of the present invention, a direction perpendicular to the length direction of the pole piece is the width direction of the pole piece, and along the width direction of the pole piece, the plurality of depressions in the embossing area are distributed throughout the pole piece.

[0015] According to some embodiments of the present invention, the cross-sectional shape of the depression in the embossed area is circular or elliptical.

[0016] The cylindrical battery according to the embodiment of the second aspect of the present invention includes the above-mentioned embossed electrode sheet.

[0017] The cylindrical battery according to the embodiment of the present invention has at least the following beneficial effects: in the battery cell of the cylindrical battery, the electrode is provided with multiple embossed areas, and multiple depressions are provided in the embossed areas, which further improves the electrolyte conductivity of the electrode surface, and the electrolyte infiltrates the electrode more fully, which can greatly improve the cycle life of the cylindrical battery; by designing and adjusting the number and position distribution of the embossed areas on the electrode, it is also possible to avoid electrode powder loss and capacity loss of the cylindrical battery.

[0018] According to some embodiments of the present invention, the embossed electrode sheet is the positive electrode sheet of the cylindrical battery.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0021] Figure 1 This is a schematic structural diagram of the embossed electrode sheet of the present invention;

[0022] Figure 2 This is a schematic structural diagram of a pole piece with a wound structure according to an embodiment of the present invention.

[0023] Figure Number:

[0024] Pole piece 100 and embossed area 200. DETAILED DESCRIPTION

[0025] The following describes in detail embodiments of the present invention. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0026] In the description of the present invention, it should be understood that descriptions involving orientation, such as the orientation or positional relationship indicated by up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0027] In the description of this utility model, "a plurality" means more than two. The use of "first" or "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0028] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0029] Traditional cylindrical batteries, specifically lithium-ion cylindrical batteries, still face the problem of lithium deposition after cell cycling due to manufacturing process limitations. This phenomenon occurs after repeated charge and discharge cycles. Generally, lithium deposition begins after 300 cycles, shortening the battery's cycle life.

[0030] When a lithium-ion cylindrical battery is being charged, if the lithium ions cannot be embedded in the negative electrode in time, they will precipitate on the surface of the negative electrode to form solid metallic lithium. This reaction is irreversible.

[0031] Lithium ions precipitate to form metallic lithium, often in the form of branched crystals known as lithium dendrites. The growth of lithium dendrites can damage the solid electrolyte interface (SEI) membrane within the battery, negatively impacting battery performance, such as reducing energy density and charge / discharge efficiency. Lithium dendrites can also puncture the separator, causing micro-short circuits within the lithium-ion battery. These micro-shorts can rapidly increase the battery temperature, potentially leading to safety hazards such as fire or explosion.

[0032] To solve the above problems, attempts have been made to emboss the entire length of the surface of the electrode sheet. However, in the actual processing process, it is difficult to control the depth of the depression when the electrode sheet is embossed all over, and it will also lead to capacity loss of the cylindrical battery.

[0033] Reference Figure 1 and Figure 2 As shown, an embossed electrode sheet according to an embodiment of the present invention includes an electrode sheet 100 and an embossed area 200 .

[0034] The pole piece 100 has a winding structure; along the winding direction of the pole piece 100, there are at least three non-continuous embossed areas 200 distributed on the surface of the pole piece 100, and the multiple embossed areas 200 are all located on the same side surface of the pole piece 100. In the embossed areas 200, the surface of the pole piece 100 is provided with a plurality of arrays of depressions.

[0035] There are multiple depressions in the embossed area 200 on the surface of the electrode 100. After being made into a battery cell or cylindrical battery, the electrolyte enters the depressions, which is beneficial to the diffusion and conduction of the electrolyte. The electrolyte infiltrates the electrode 100 more fully, which can further improve the cycle life of the cylindrical battery. If there is an area on the electrode 100 that the electrolyte cannot penetrate, the active material in the area cannot participate in the reaction. The embossed area 200 is set discontinuously, that is, the electrode 100 is not fully provided with the embossed area 200, which can ensure the capacity of the cylindrical battery. This is because the depressions are set in the embossed area 200, and the electrode 100 needs to be squeezed with external force, which will inevitably cause the active material coated on the surface of the electrode 100 to be damaged and reduced, and the substances participating in the reaction are reduced, which means that the capacity of the cylindrical battery is reduced.

[0036] It should be understood that the embossed area 200 can be provided on any side surface of the electrode sheet 100, as long as all the embossed areas 200 on the electrode sheet 100 are on the same side surface. Because after the electrode sheet 100 is wound to form a wound structure, assuming that the electrode sheet 100 is a positive electrode sheet, then the inner side of the electrode sheet 100 corresponds to the negative electrode sheet, and the outer side of the electrode sheet 100 also corresponds to the negative electrode sheet, the effect of the embossed area 200 on any side surface is the same.

[0037] It should be understood that the embossed area 200 refers to the embossed area on the electrode 100, that is, the embossed area 200 is provided with a plurality of arrays of depressions on the surface of the electrode 100. In the actual processing process, the electrode embossing roller is installed at the positive electrode processing station of the winding machine, and a rubber roller is installed on the opposite side of the electrode embossing roller. The electrode 100 passes between the electrode embossing roller and the rubber roller. Under the drive of the electrode embossing roller, a plurality of arrays of depressions are left in the predetermined embossing area 200, that is, on the surface of the electrode 100.

[0038] The position of the embossing area 200 distributed on the surface of the electrode 100 is set manually. Specifically, during the processing, the program of the winding machine can be used to execute the working section of the electrode embossing roller, that is, the distribution of the embossing area 200 can be controlled by writing the embossing start and end ends into the program.

[0039] The surface of the electrode embossing roller has multiple embossed patterns, and adjusting the torque of the electrode embossing roller can control the depth of the depression caused by the electrode 100. For example, in some embodiments, the surface of the electrode 100 is provided with five embossing areas 200. Along the winding direction of the electrode 100, the torques of the electrode embossing roller corresponding to the five embossing areas 200 are 50N to 110N, 110N to 160N, 160N to 200N, 110N to 160N, and 50N to 110N, respectively. The corresponding embossing depths are 20μm to 40μm, 40μm to 60μm, 60μm to 80μm, 40μm to 60μm, and 20μm to 40μm, respectively.

[0040] It can be understood that the area of ​​the pole piece 100 close to the winding center is the inner ring, the area of ​​the pole piece 100 away from the winding center is the outer ring, and multiple embossed areas 200 are distributed in the outer ring, the inner ring, and the area between the outer ring and the inner ring.

[0041] Preferably, there are five embossed areas 200 distributed on the surface of the pole piece 100, wherein the outer ring has two embossed areas 200, the area between the outer ring and the inner ring has one embossed area 200, and the inner ring has two embossed areas 200. In some embodiments, the embossed area 200 between the outer ring and the inner ring can be set at the center of the entire pole piece 100, corresponding to the middle ring of the winding structure of the pole piece 100. Preferably, the two embossed areas 200 set on the outer ring refer to the outermost two rings of the winding structure of the pole piece 100 having embossed areas 200, and the two embossed areas 200 set on the inner ring refer to the innermost two rings of the winding structure of the pole piece 100 having embossed areas 200.

[0042] It can be understood that the depths of the depressions in different embossing areas 200 are different, and along the winding direction of the pole piece 100 , the depths of the depressions in different embossing areas 200 change from shallow to deep and then to shallow again.

[0043] For example, in some embodiments, the pole piece 100 is distributed with five embossed areas 200 . Along the winding direction of the pole piece 100 , the corresponding depths of the depressions in the five embossed areas 200 are 30 μm, 50 μm, 70 μm, 50 μm, and 30 μm, respectively.

[0044] It should be understood that the depths of the depressions in different embossing areas 200 are different. Furthermore, the depths of the depressions in the same embossing area 200 can also be different, but the depths of the depressions in the same embossing area 200 need to satisfy a smooth transition. Taking the five sections of the embossed area 200 with the depths of the depressions being 20μm to 40μm, 40μm to 60μm, 60μm to 80μm, 40μm to 60μm, and 20μm to 40μm as an example, for example, the depression depth of the first section of the embossed area 200 satisfies the requirement of gradually becoming deeper from 20μm to 40μm, the depression depth of the second section of the embossed area 200 satisfies the requirement of gradually becoming deeper from 40μm to 60μm, the depression depth of the third section of the embossed area 200 satisfies the requirement of gradually becoming deeper from 60μm to 80μm and then gradually becoming shallower from 80μm to 60μm, the depression depth of the fourth section of the embossed area 200 satisfies the requirement of gradually becoming shallower from 60μm to 40μm, and the depression depth of the fifth section of the embossed area 200 satisfies the requirement of gradually becoming shallower from 40μm to 20μm.

[0045] It can be understood that the thickness of the pole piece 100 is a, and the depth of the depression in the embossed area 200 is 0.2a to 0.5a.

[0046] The depth of the depression can be adjusted according to the degree of lithium deposition in the cylindrical battery. For example, in locations where lithium deposition is severe, the depth of the depression is greater, that is, the degree of embossing is higher; in locations where lithium deposition is less severe, the depth of the depression is smaller, that is, the degree of embossing is lower. Controlling the depth of the depression within the range of 0.2a to 0.5a can reduce the risk of powder loss from the electrode 100 due to excessive embossing. Because depressions are created by embossing the surface of the electrode 100, they may damage the material coated on the surface of the electrode 100, causing severe shedding of the coating material, i.e., powder loss. Generally, in cylindrical batteries, lithium deposition tends to occur at the outer ring position, inner ring position, and the middle position between the outer ring and the inner ring of the electrode winding structure. Moreover, the lithium deposition in the middle position is more severe than that in the outer ring or inner ring. Therefore, the depth of the depression in the embossed area 200 tends to change from shallow to deep and then shallow again, that is, the depression at the outer ring and inner ring position is shallower, and the depression at the middle position between the inner ring and the outer ring is deeper.

[0047] It can be understood that the winding direction of the pole piece 100 is the length direction of the pole piece 100 , and the length of the embossed area 200 is 2πd, where d is the diameter of the winding structure of the pole piece 100 .

[0048] Cylindrical batteries of different sizes have different diameters of the winding structure of the electrode 100. Cylindrical batteries of different sizes have different battery capacities and lithium deposition levels. The length of the embossed area 200 can be determined by the winding structure of the electrode 100, so that the length of the embossed area 200 is adapted to the lithium deposition level, thereby extending the cycle life of the cylindrical battery.

[0049] It can be understood that the direction perpendicular to the length direction of the pole piece 100 is the width direction of the pole piece 100 , and along the width direction of the pole piece 100 , the plurality of depressions in the embossed area 200 are distributed throughout the pole piece 100 .

[0050] It should be understood that, on one side of the pole piece 100 , there is also a pole ear portion along the winding direction. The pole ear is different from the pole piece, and no embossing area 200 is provided at the pole ear.

[0051] It is understood that the cross-sectional shape of the depression in the embossed area 200 is circular or elliptical. Compared with other angular shapes, circular or elliptical depressions are less likely to cause powdering of the pole piece 100.

[0052] A cylindrical battery according to an embodiment of the present invention includes the above-mentioned embossed electrode sheet. Furthermore, in some embodiments, the embossed electrode sheet is a positive electrode sheet of the cylindrical battery.

[0053] In some embodiments, a pole piece embossing roller is installed at the positive pole piece processing station of the winding machine, and a rubber roller is set at the opposite side of the pole piece embossing roller, and the pole piece 100 passes between the pole piece embossing roller and the rubber roller. Under the drive of the pole piece embossing roller, a plurality of arrays of depressions are left in the predetermined embossing area 200, that is, on the surface of the pole piece 100. The position of the embossing area 200 distributed on the surface of the pole piece 100 is manually set. Specifically, in the processing process, the program of the winding machine can be used to execute the working section of the pole piece embossing roller, that is, the distribution of the embossing area 200 is controlled by writing the embossing start and end ends into the program. At the embossing start end, the pole piece embossing roller increases the torque to the embossing torque, and at the embossing end end, the pole piece embossing roller reduces the torque until no depression is generated on the pole piece 100. The length of the pole piece embossing roller can correspond to the width of the pole piece 100, so that the multiple depressions in the embossing area 200 cover the width of the pole piece 100.

[0054] Adjusting the torque of the electrode embossing roller can also control the depth of the depression created by the electrode embossing roller on the surface of the electrode 100. Before formal processing, a sample electrode can be placed, and by adjusting the torque of the electrode embossing roller and measuring the depth of the depression on the surface of the sample electrode, the corresponding relationship between torque and depth can be obtained.

[0055] Taking five-section embossing as an example, 32 processes were performed, and the relevant parameters collected for each process were summarized in the following table.

[0056] Table 1 Process parameters for segmented embossing of electrode pieces

[0057]

[0058] At the same time, the influence of different torque settings of the pole piece embossing roller on the depression depth of the embossing area was also tested, and the data in the following table was obtained.

[0059] Table 2 Corresponding relationship between different torque settings and embossing depth

[0060]

[0061] Comparative Example 1:

[0062] There is no embossed area on the electrode. The electrode is used to make a battery cell and a cylindrical battery, and a cycle charge and discharge experiment is carried out on the cylindrical battery.

[0063] Comparative Example 2:

[0064] There are two embossed areas on the electrode, and the embossed areas are respectively located in the outer circle and inner circle of the winding structure of the electrode. The other parameters are consistent with those of comparative example 1. The electrode is used to make a battery cell and a cylindrical battery, and a cyclic charge and discharge experiment is carried out on the cylindrical battery.

[0065] Comparative Example 3:

[0066] There are four embossed areas on the electrode, two embossed areas on the outer circle of the winding structure of the electrode, and two embossed areas on the inner circle. The other parameters are consistent with those of Comparative Example 1. The electrode is used to make battery cells and cylindrical batteries, and the cylindrical batteries are subjected to cyclic charge and discharge experiments.

[0067] Example 4:

[0068] There are five embossed areas distributed on the electrode, two embossed areas distributed on the outer circle of the winding structure of the electrode, two embossed areas distributed on the inner circle, and one embossed area distributed between the outer circle and the inner circle. The other parameters are consistent with those of Comparative Example 1. The electrode is used to make battery cells and cylindrical batteries, and the cylindrical batteries are subjected to cyclic charge and discharge experiments.

[0069] Comparative Example 5:

[0070] The entire length of the electrode is embossed, that is, the embossed area is distributed at all positions of the electrode. The other parameters are consistent with those of Comparative Example 1. The electrode is used to make a battery cell and a cylindrical battery, and a cyclic charge and discharge experiment is carried out on the cylindrical battery.

[0071] The following table was obtained after the cyclic charge and discharge experiments on the above five cylindrical batteries were carried out.

[0072] Table 3 Cyclic battery cycle benefits

[0073]

[0074] As shown in the data in Table 3, the embossed electrode sheet of the present invention and the cylindrical battery using the same can reduce the degree of lithium plating during the battery cycle and extend the cycle life of the battery.

[0075] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. An embossed electrode sheet, characterized in that: It comprises a pole piece (100), wherein the pole piece (100) is a winding structure; At least three discontinuous embossed areas (200) are distributed on the surface of the pole piece (100) along the winding direction of the pole piece (100), and the plurality of embossed areas (200) are all located on the same side surface of the pole piece (100). In the embossed areas (200), the surface of the pole piece (100) is provided with a plurality of depressions distributed in an array.

2. The embossed electrode sheet according to claim 1, characterized in that: The area of ​​the pole piece (100) close to the winding center is the inner ring, the area of ​​the pole piece (100) away from the winding center is the outer ring, and the plurality of embossed areas (200) are distributed on the outer ring, the inner ring, and a portion between the outer ring and the inner ring.

3. The embossed electrode sheet according to claim 2, characterized in that: Five embossed areas (200) are distributed on the surface of the pole piece (100), wherein the outer ring has two embossed areas (200), the portion between the outer ring and the inner ring has one embossed area (200), and the inner ring has two embossed areas (200).

4. The embossed electrode sheet according to claim 1, characterized in that: The depths of the depressions in different embossed areas (200) are different.

5. The embossed electrode sheet according to claim 4, characterized in that: The thickness of the pole piece (100) is a, and the depth of the depression in the embossed area (200) is 0.2a to 0.5a.

6. The embossed electrode sheet according to claim 1, characterized in that: The length of each embossed area (200) is 2πd, wherein d is the diameter of the winding structure of the pole piece (100).

7. The embossed electrode sheet according to claim 6, characterized in that: Along the width direction of the pole piece (100), the plurality of depressions in the embossed area (200) are distributed throughout the pole piece (100).

8. The embossed electrode sheet according to claim 2, characterized in that: The cross-sectional shape of the depression in the embossed area (200) is circular or elliptical.

9. A cylindrical battery, characterized in that: The embossed electrode sheet comprises the embossed electrode sheet according to any one of claims 1 to 8.

10. The cylindrical battery according to claim 9, characterized in that: The electrode sheet with embossing is the positive electrode sheet of the cylindrical battery.

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