Pole piece and battery

Abstract

The utility model discloses a pole piece and a battery, the pole piece comprises: a pole piece body provided with a plurality of grooves, the plurality of grooves are distributed at intervals along the length direction of the pole piece body, and each groove extends along the width direction of the pole piece body; and the projections of any two adjacent grooves on the long edge of the pole piece body have an overlapped part. When the pole piece disclosed by the utility model is wound into a battery cell, the grooves are formed in the corner positions, so that the condition that the corner positions have no holes can be effectively avoided, the lithium precipitation at the corner is improved, the electrolyte wettability in the charging and discharging processes of the battery is improved, and the cycle life is further prolonged.

Description

Technical Field

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

[0002] In the research and development and production of lithium-ion batteries, continuously improving battery performance has always been the core pursuit of the industry.

[0003] Under current technology, to effectively improve the electrolyte wetting effect of lithium-ion batteries during charging and discharging, suppress lithium plating, and thus extend battery life, such as... Figure 1 As shown, the industry commonly uses laser drilling of straight holes on the negative electrode sheet, which effectively improves the overall performance of the battery to a certain extent and lays the foundation for the widespread application of lithium-ion batteries.

[0004] However, as Figure 1 As shown, the straight holes formed by the current process are spaced apart along the length of the electrode and parallel to the width of the electrode. When the electrode is wound to form a cell, the coatings on the side of the electrode corner closer to the core are squeezed together, which may result in a situation where there are no holes. Due to the lack of effective perforation treatment at the corners, the problem of lithium plating at the corners is difficult to improve effectively, which has a serious negative impact on the long-term cycle stability of the cell. Utility Model Content

[0005] The main purpose of this invention is to propose an electrode sheet that aims to solve the technical problem that existing perforated electrode sheets may not have holes at corner positions when being wound into battery cells.

[0006] To achieve the above objectives, this utility model proposes an electrode sheet, which includes:

[0007] The electrode body has multiple grooves, which are spaced apart along the length of the electrode body, and each groove extends along the width of the electrode body.

[0008] Wherein, the projections of any two adjacent grooves on the length direction of the electrode body overlap.

[0009] In some embodiments, the extension direction of the starting segment of the groove forms a first included angle α with the length direction of the electrode body, satisfying: 0° < α < 90°.

[0010] In some embodiments, the distance between any two adjacent grooves is D;

[0011] The projection dimension of the groove along the length of the electrode is H, which satisfies: H>D.

[0012] In some embodiments, the length of the electrode is L, the width of the groove is W, and the number of grooves is N, wherein N = L / (D + W).

[0013] In some embodiments, the length of the electrode sheet ranges from 50 mm to 2000 mm, the groove width ranges from 0.02 mm to 0.2 mm, and the distance between any two adjacent grooves ranges from 0.5 mm to 5 mm.

[0014] In some embodiments, the projection of the groove onto the length direction of the electrode body has a first endpoint and a second endpoint. The first endpoint is the starting point of the groove, and the second endpoint corresponds to the farthest point of the groove extending along the length direction of the electrode body. The line connecting the starting point of the groove and the farthest point of the groove extending along the length direction of the electrode body forms a second included angle β with the length direction of the electrode body, satisfying: 0° < β < 90°.

[0015] In some embodiments, α ≤ β is also satisfied.

[0016] In some embodiments, the projection shape of the groove in the thickness direction of the electrode body is at least one of oblique line, sawtooth shape, and wave shape.

[0017] In some embodiments, the electrode body has two opposing long edges, and the groove extends from one long edge of the electrode body to the other long edge of the electrode body.

[0018] This utility model also proposes a battery, which includes:

[0019] case;

[0020] A core is disposed in the housing, the core comprising an anode electrode, a diaphragm and a cathode electrode arranged in layers and wound together;

[0021] Wherein, at least one of the anode electrode and the cathode electrode includes the electrode as described above.

[0022] In this invention, the electrode body has multiple grooves, which are spaced apart along the length of the electrode body, and each groove extends along the width of the electrode body. Since the projections of any two adjacent grooves on the length of the electrode body at least partially overlap, when the electrode is wound into a battery cell, the corner positions have grooves, which can effectively prevent the corner positions from being without holes, thereby improving lithium plating at the corners, enhancing the electrolyte wettability during battery charging and discharging, and thus improving cycle life. Attached Figure Description

[0023] Figure 1This is a schematic diagram of the structure of a single electrode in the prior art;

[0024] Figure 2 This is a schematic diagram of the electrode sheet in one embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the electrode structure in another embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the electrode sheet in another embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the electrode sheet in another embodiment of the present invention;

[0028] Explanation of reference numerals in the attached figures:

[0029]

[0030] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0031] The solutions in 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 a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0032] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0033] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.

[0034] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0035] This utility model embodiment proposes an electrode sheet, referring to... Figure 2 The electrode includes:

[0036] The electrode body 100 has a plurality of grooves 101, which are distributed at intervals along the length x direction of the electrode body 100, and each groove 101 extends along the width Y direction of the electrode body 100.

[0037] Among them, the projections 101T of any two adjacent grooves 101 onto the long edge 110 of the electrode body 100 overlap.

[0038] In this embodiment, the electrode can be a negative electrode (also called an anode electrode), which can be stacked and wound together with a positive electrode (also called a cathode electrode), a separator, etc., to form a core. The core has a straight section and corner sections located at both ends of the straight section. Corresponding to the straight section of the core, the electrode is formed in a straight position; and corresponding to the corner section of the core, the electrode is formed in a corner position.

[0039] The electrode body 100 is rectangular, with a length direction x and a width direction Y. During the fabrication of the wound cell, the electrode is wound along the length direction x of the electrode body 100. Correspondingly, the edge extending along its length direction x of the electrode body 100 is the long side edge 110, and the edge extending along its width direction Y of the electrode body 100 is the short side edge 120. The grooves 101 provided on the electrode body 100 serve as important channels for the flow of electrolyte within the battery. During battery charging and discharging, the electrolyte can quickly pass through the grooves 101 and be evenly distributed throughout the electrode. The grooves 101 can be formed by laser drilling. Compared to other drilling methods, laser drilling causes minimal damage to the electrode body 100. The laser beam has concentrated energy and a short action time, ensuring that the formation of the grooves 101 on the electrode body 100 does not significantly damage the overall structure of the electrode body 100, thus maintaining its mechanical strength.

[0040] The electrode body 100 has multiple grooves 101, which are spaced apart along the length x of the electrode body 100. Optionally, the grooves 101 are evenly distributed between one end and the other end of the electrode body 100 along the length x of the electrode body 100. Furthermore, each groove 101 extends along the width Y of the electrode body 100. The specific number of grooves 101 can be set according to actual needs, and the extension length of the grooves 101 is not limited.

[0041] The hole shape of the groove 101 can be varied. For example, the groove 101 can be an oblique hole inclined relative to the length direction x or width direction Y of the electrode body 100. Other shapes are also possible. Multiple grooves 101 can have the same or different hole shapes; there are no restrictions. Furthermore, by adjusting the laser drilling parameters, different hole shapes can be created to meet the actual manufacturing needs of the electrode.

[0042] Multiple grooves 101 on the electrode body 100 are distributed at intervals along its length direction x. The grooves 101 can be projected 101T to the long side edge 110 of the electrode body 100. Specifically, the projections 101T of any two adjacent grooves 101 onto the long edge 110 of the electrode body 100 at least partially overlap. This partial overlap can be a point coincidence, such as the endpoint of the projection 101T of one groove 101 onto the long edge 110 of the electrode body 100 coinciding with the starting endpoint of the projection 101T of the other groove 101 onto the long edge 110 of the electrode body 100. It can also be a line coincidence, such as a segment of the projection 101T of one groove 101 onto the long edge 110 of the electrode body 100 coinciding with a segment of the projection 101T of the other groove 101 onto the long edge 110 of the electrode body 100. Multiple grooves 101 are arranged sequentially to cover all positions (including straight and corner positions) of the electrode body 100 along its length x. Since the projections 101T of any two adjacent grooves 101 on the length direction x of the electrode body 100 at least partially overlap, when the electrode is wound into a cell, there are grooves 101 at the corner position, which can effectively avoid the situation of no holes at the corner position, thereby improving the corner lithium plating, improving the electrolyte wettability during battery charging and discharging, and thus improving cycle life.

[0043] From another perspective, there is no need to pre-calculate the corner positions of the electrode based on the cell size and then drill holes at the corresponding corner positions. In this embodiment, the electrode can be directly used to make cells of various sizes, which greatly simplifies the manufacturing process, improves production efficiency, and reduces production costs.

[0044] In some embodiments, refer to Figure 3 and Figure 4 The extension direction of the starting segment of the groove 101 forms a first included angle α with the length direction x of the electrode body 100, satisfying: 0°<α<90°.

[0045] Since the groove 101 extends along the width direction Y of the electrode body 100, the groove 101 has a starting segment and an ending segment. The starting segment of the groove 101 is adjacent to one long edge 110 of the electrode body 100, while the ending segment of the groove 101 is adjacent to the other long edge 110 of the electrode body 100. When determining the position and direction of the starting segment of the groove 101, a first angle α is formed between the extending direction of the starting segment of the groove 101 and the length direction x of the electrode body 100, and the angle α is between 0° and 90°. This ensures that after drilling, the groove 101 can have a projection 101T on the long edge 110 of the electrode body 100, thus covering a portion of the electrode body 100 along the length direction x.

[0046] In some embodiments, refer to Figure 3 and Figure 4 The distance between any two adjacent grooves 101 is D;

[0047] The projection dimension of the groove 101 on the length direction x of the electrode body 100 is H, which satisfies: H>D.

[0048] In this embodiment, multiple grooves 101 are uniformly distributed along the length x of the electrode body 100, and the distance between any two adjacent grooves 101 is equal, both being D. During battery charging and discharging, the electrolyte can flow through each groove 101 at a stable flow rate and volume, avoiding local electrolyte accumulation or shortage caused by uneven distribution of the grooves 101, thereby achieving a more uniform distribution in various regions of the electrode. Furthermore, the shape of the grooves 101 varies with amplitude along the length x of the electrode body 100, and the shape can be varied in various ways, such as sawtooth holes, wave-shaped holes, etc., with different shapes exhibiting amplitude variations. The grooves 101 can have a projection along the length x of the electrode body 100, and the projection size is H, where H > D. By controlling the projection size of the groove 101 on the length direction x of the electrode body 100 to be greater than the spacing of the grooves 101, when two adjacent grooves 101 are projected onto the long side edge 110 of the electrode body 100, their projections 101T overlap.

[0049] In some embodiments, the length of the electrode is L, the width of the groove 101 is W, and the number of grooves 101 is N, where N = L / (D+W). In the actual manufacturing process of the electrode, there is a close relationship between the length L of the electrode, the width W of the groove 101, and the number N of the grooves 101. First, when determining the size of the electrode, the length L of the electrode is accurately measured and set according to the battery design requirements and application scenarios. Simultaneously, based on factors such as the fluidity of the electrolyte, ion transport efficiency, and the mechanical strength of the electrode, a suitable groove width W of the groove 101 is determined through experimental and simulation analysis.

[0050] During the drilling operation, the required number of grooves 101 is calculated according to the formula N = L / (D + W). Here, D, as defined in the previous embodiment, represents the spacing between two adjacent grooves 101, which also needs to be reasonably set according to the performance requirements of the electrode. When using a laser drilling device, the calculated number of grooves 101 N, the hole width W, and the spacing D are input into the device control system. The device will perform the drilling operation along the length x of the electrode body 100 according to the preset parameters, with precise spacing and hole width. For example, if the electrode length L is 100mm, the hole width W is determined to be 1mm after testing, and the spacing D between adjacent grooves 101 is 4mm, then the calculated number of grooves 101 N is 20. The laser drilling device uniformly drills 20 grooves 101 with a width of 1mm and a spacing of 4mm on the electrode body 100 according to these parameters.

[0051] In this embodiment, by rationally setting the relationship between the electrode length, the groove width and the number of grooves 101, the transport path of the electrolyte in the electrode can be optimized. An appropriate number of grooves 101 and an appropriate groove width can improve the uniformity of electrolyte distribution on the electrode and enable it to flow rapidly inside the electrode during charging and discharging, providing a sufficient supply of electrolyte for the chemical reaction inside the battery, thereby improving the charging and discharging performance of the battery.

[0052] In some embodiments, the length of the electrode sheet ranges from 50 mm to 2000 mm, the groove width of the groove 101 ranges from 0.02 mm to 0.2 mm, and the distance between any two adjacent grooves 101 ranges from 0.5 mm to 5 mm.

[0053] Based on the battery design requirements and application scenarios, the electrode length L is determined to be between 50mm and 2000mm. For small electronic device batteries, a shorter electrode length, such as 50mm, can be selected; for large power battery packs, a longer electrode length, such as 2000mm, can be selected. Simultaneously, considering factors such as electrolyte flowability, ion transport efficiency, and electrode mechanical strength, the groove width W of the groove 101 is determined to be between 0.02mm and 0.2mm. For electrolytes with better flowability, the groove width can be appropriately reduced; if the mechanical strength of the electrode is considered, a larger groove width value can be selected within the range. As for the groove spacing 101, its range is between 0.5mm and 5mm, which can be set according to the performance requirements of the electrode.

[0054] Based on the calculation formula for the number of grooves 101 in the above embodiment, and combined with the value range of each parameter, the number N of grooves 101 can be determined to be between 9 and 3847. Specifically, when the electrode length L is the minimum value of 50mm, the groove width of groove 101 is the maximum value of 0.2mm, and the spacing between grooves 101 is the maximum value of 5mm, the number N of grooves 101 can be calculated to be approximately 9.6, rounded down to 9, which is the minimum number of grooves 101. When the electrode length L is the maximum value of 2000mm, the groove width of groove 101 is the minimum value of 0.02mm, and the spacing between grooves 101 is the minimum value of 0.5mm, the number N of grooves 101 can be calculated to be approximately 3846.1, rounded down to 3847. Therefore, the number N of grooves 101 can be set between 9 and 3847.

[0055] In some embodiments, the design of the groove 101 on the electrode sheet, in addition to the aforementioned parameters and features, refers to... Figures 3 to 5 Furthermore, the projection of the groove 101 onto the length x of the electrode body 100 has a first endpoint and a second endpoint. The first endpoint is the starting point of the groove 101, and the second endpoint corresponds to the farthest point of the groove 101 extending along the length x of the electrode body 100. The line connecting the starting point of the groove 101 and the farthest point of the groove 101 extending along the length x of the electrode body 100 forms a second included angle β with the length x of the electrode body 100, satisfying: 0°<β<90°.

[0056] In the laser drilling process of a laser drilling machine, the setting of this parameter affects the specific operation of the laser drilling. By controlling the second included angle β formed between the line connecting the starting point of the groove 101 and the farthest point extending along the length x of the electrode body 100 and the length x of the electrode body 100, which is between 0° and 90°, the groove 101 produced exhibits amplitude variation, meeting the design requirements. Taking a sawtooth hole as an example, not only must parameters such as the tooth height and tooth pitch of the sawtooth be set, but the tilt direction and angle of the sawtooth must also be determined according to the second included angle β, thereby realizing the specific groove shape design of the groove 101.

[0057] Optionally, in some embodiments, reference is made to Figures 3 to 5 It also satisfies: α≤β. That is, the first included angle α can be less than the second included angle β, for example, ... Figure 5 As shown, the groove 101 can be a wave-shaped hole, with a first included angle α of 15° and a second included angle β of 30°; or, the first included angle β is equal to the second included angle β, for example... Figure 4 As shown, the groove 101 can be a sawtooth hole, with the first included angle α and the second included angle β both being 45°.

[0058] In some embodiments, the projection shape of the groove 101 on the thickness direction of the electrode body 100 is at least one of oblique line, sawtooth shape, and wave shape.

[0059] In this embodiment, the thickness direction of the electrode body 100 is perpendicular to both the length direction x and the width direction Y of the electrode body 100. The projection shape of the groove 101 in the thickness direction of the electrode body 100 can be an oblique line. When the groove 101 adopts an oblique groove shape, it is inclined relative to the length direction x of the electrode body 100. There is an angle between the groove 101 and the long edge 110 of the electrode body 100. This angle can be 30°, 45°, 60°, etc., and is not limited thereto. When making the oblique groove, the laser drilling path is determined according to the pre-set inclination angle of the oblique hole relative to the long edge 110 of the electrode body 100. The laser drilling equipment performs laser scanning on the electrode body 100 along the laser drilling path, thereby drilling the oblique groove on the electrode body 100.

[0060] Besides the oblique hole, the projection shape of the groove 101 in the thickness direction of the electrode body 100 can also be as follows: Figure 4 As shown, when making the sawtooth groove, the laser beam scanning trajectory is set according to the pre-set sawtooth shape and size through the control system of the laser drilling equipment. For example, if the tooth height is set to 0.1mm and the tooth pitch is set to 0.2mm, the laser beam will sequentially drill a series of small holes on the electrode body 100 according to the set trajectory during the scanning process, and connect them to form a sawtooth groove.

[0061] Besides oblique lines and sawtooth shapes, the projection shape of the groove 101 on the thickness direction of the electrode body 100 can also be as follows: Figure 5 The waveform shown can be either a sine wave or a cosine wave when the groove shape of groove 101 is waveform-like, depending on the actual requirements. The fabrication of the waveform groove also requires precise control of the laser drilling equipment. By adjusting the frequency and amplitude of the laser scan, the laser beam scans the electrode sheet according to a predetermined waveform trajectory. For example, setting the waveform amplitude to 0.2mm and the frequency to 10Hz, the laser beam moves up and down at a frequency of 10Hz with an amplitude of 0.2mm during the scanning process, thereby forming a regular waveform groove on the electrode sheet.

[0062] In some embodiments, refer to Figures 2 to 5 The electrode body 100 has two opposing long edges 110, and a groove 101 extends from one long edge 110 to the other long edge 110 of the electrode body 100. In this embodiment, the groove length of the groove 101 is greatly extended along the width direction Y of the electrode body 100. When the electrolyte passes through the groove 101, since the groove 101 almost covers the entire width direction Y of the electrode, the electrolyte is more evenly distributed at various positions along the width direction Y of the electrode. This effectively avoids insufficient reaction in local areas due to insufficient electrolyte, helps to improve the overall consistency and stability of the battery, and thus extends the battery's service life.

[0063] This utility model also proposes a battery, which includes:

[0064] case;

[0065] A core is disposed in the housing, and the core includes an anode electrode, a diaphragm, and a cathode electrode that are stacked and wound together.

[0066] The anode and cathode electrodes include at least one electrode as described in the foregoing embodiments.

[0067] The specific structure of the electrode is as described in the above embodiments. Since this battery adopts all the technical solutions of all the above embodiments, it has at least all the technical effects brought about by the technical solutions of the above embodiments, and will not be described in detail here. In this battery, the anode electrode of the winding core can be the electrode as described in the above embodiments, and / or the cathode electrode of the winding can be the electrode as described in the above embodiments.

[0068] The above description is only a part or preferred embodiment of this utility model. Neither the text nor the drawings should limit the scope of protection of this utility model. All equivalent structural transformations made using the content of this utility model specification and drawings under the overall concept of this utility model, or direct / indirect applications in other related technical fields, are included within the scope of protection of this utility model.

Claims

1. A pole piece, characterized in that, The pole piece body is provided with a plurality of grooves, the plurality of grooves are distributed at intervals along the length direction of the pole piece body, and each groove extends along the width direction of the pole piece body. The projections of any two adjacent grooves on the long edge of the pole piece body overlap. The first included angle α between the extension direction of the starting section of the groove and the length direction of the pole piece body satisfies 0°<α<90°.

2. The pole piece of claim 1, wherein The distance between any two adjacent grooves is D.

3. The pole piece of claim 2, wherein The projection size of the groove in the length direction of the pole piece satisfies H>D. The length of the pole piece is L, the groove width of the groove is W, and the number of the grooves is N, wherein N=L / (D+W) is satisfied.

4. The pole piece of claim 3, wherein The length of the pole piece ranges from 50mm to 2000mm, the groove width of the groove ranges from 0.02mm to 0.2mm, and the distance between any two adjacent grooves ranges from 0.5mm to 5mm.

5. The pole piece of claim 4, wherein The projection of the groove in the length direction of the pole piece body has a first endpoint and a second endpoint, the first endpoint is the starting point of the groove, the second endpoint corresponds to the farthest point of the groove extending in the length direction of the pole piece body, and the direction of the line connecting the starting point of the groove and the farthest point of the groove extending in the length direction of the pole piece body forms a second included angle β with the length direction of the pole piece body, which satisfies 0°<β<90°.

6. The pole piece of claim 3, wherein It is also satisfied that α≤β.

7. The pole piece of claim 6, wherein The projection shape of the groove in the thickness direction of the pole piece body is at least one of diagonal, zigzag, and wave.

8. The pole piece of claim 2, wherein, The pole piece body has two opposite long edges, and the groove extends from one long edge of the pole piece body to the other long edge of the pole piece body.

9. The pole piece according to any one of claims 1 to 8, characterized in that The shell; 10. A battery, characterized by The core is provided in the shell, and the core includes an anode pole piece, a diaphragm, and a cathode pole piece which are stacked and wound; At least one of the anode pole piece and the cathode pole piece includes the pole piece according to any one of claims 1 to 9. ​ ​

Images