Pole piece and battery cell

Abstract

The utility model discloses an electrode plate and electric core. The utility model discloses an electrode plate includes current collector and active material layer, and active material layer coats the surface of current collector, and active material layer includes the first coating area and second coating area of setting along the first direction, and second coating area includes the first coating section and second coating section of interval setting along the second direction, and the mounting groove for accommodating the tab is defined between first coating section, second coating section. The electrode plate forms the mounting groove through the zoned coating, need not laser cleaning grooving, avoided the damage of laser cleaning to polymer layer, and the good product rate of electrode plate is promoted.

Description

Technical Field

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

[0002] Composite current collectors are a new type of battery current collector material, which is made by combining polymer materials and metals. Existing composite current collectors have a "sandwich" structure, with an inner polymer layer (such as PET, PP or PI) and two metal conductive layers (such as Al or Cu) on both sides. They have high tensile strength and high elongation, which can restrain cyclic expansion and alleviate electrode breakage.

[0003] In existing technologies, laser cleaning is often used to remove part of the active material layer from the current collector to form a groove for welding the electrode tab to the current collector. However, since the inner layer of the composite current collector is a polymer layer, it is easily burned during laser cleaning, leading to problems such as wrinkling and deformation of the current collector after laser cleaning, which greatly restricts the improvement of electrode yield. Utility Model Content

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an electrode that eliminates the need for laser cleaning and grooving, avoiding damage to the polymer layer caused by laser cleaning and improving the electrode yield.

[0005] This utility model also proposes a battery cell having the above-mentioned electrode plates.

[0006] The electrode sheet according to a first aspect embodiment of the present invention includes:

[0007] current collector;

[0008] An active material layer is coated on the surface of the current collector. The active material layer includes a first coating area and a second coating area disposed along a first direction. The second coating area includes a first coating segment and a second coating segment disposed at intervals along a second direction. A mounting groove for accommodating the tab is defined between the first coating segment and the second coating segment.

[0009] The electrode sheet according to the embodiments of this utility model has at least the following beneficial effects:

[0010] In this solution, the active material layer is coated in sections, with the active material not pre-coated in the tab welding area, creating an exposed current collector area. This eliminates the need for laser cleaning and grooving, avoiding damage to the polymer layer caused by laser cleaning, ensuring a smooth current collector, and improving the electrode yield. Furthermore, since the electrodes produced using this solution do not require laser cleaning after the coating process, manufacturing time and production costs are saved.

[0011] According to some embodiments of the present invention, the active material layer further includes a connecting region located between the first coating area and the second coating area. The first coating area includes a first main body portion, and the second coating area includes a second main body portion. The second main body portion includes the first coating segment and the second coating segment disposed at intervals. The connecting region includes a first connecting portion connected to the first main body portion and a second connecting portion connected to the second main body portion. The first connecting portion and the second connecting portion are connected.

[0012] According to some embodiments of the present invention, the thickness of the connecting area is not less than the thickness of the first coating area or the thickness of the second coating area.

[0013] According to some embodiments of the present invention, the thickness of the connecting area is less than the thickness of the first coating area or the thickness of the second coating area;

[0014] In this case, the thickness of the first connecting portion gradually decreases along the direction away from the first main body portion, and the thickness of the second main body portion gradually decreases along the direction away from the second main body portion.

[0015] According to some embodiments of the present invention, the thickness Y of the connecting area and the thickness X1 of the first coating area have the following relationship: 0.95≤Y / X1≤1.05; and / or, the thickness Y of the connecting area and the thickness X2 of the second coating area have the following relationship: 0.95≤Y / X2≤1.05.

[0016] According to some embodiments of the present invention, along the first direction, the width of the connecting area is W, wherein 0mm≤W≤5mm.

[0017] According to some embodiments of the present invention, the current collector includes a composite layer and two metal layers, with the two metal layers respectively connected to both sides of the composite layer.

[0018] According to some embodiments of the present invention, the electrode further includes a base coating layer disposed between the active material layer and the current collector.

[0019] According to some embodiments of the present invention, the difference between the areal density A of the first coating area and the areal density B of the second coating area is within 3 mg.

[0020] And / or, the difference between the thickness M of the first coating area and the thickness N of the second coating area is within 1 μm.

[0021] The battery cell according to a second aspect of the present invention includes the electrode sheets described in any of the above embodiments.

[0022] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0024] Figure 1 This is a cross-sectional view of the electrode sheet according to an embodiment of the present utility model;

[0025] Figure 2 This is a top view of the electrode sheet in an embodiment of the present utility model;

[0026] Figure 3 This is a top view of the electrode mother roll according to an embodiment of the present utility model;

[0027] Figure 4 This is an enlarged cross-sectional view of the connecting area in an embodiment of the present utility model;

[0028] Figure 5 This is an enlarged cross-sectional view of the connecting area according to another embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram of the current collector structure according to an embodiment of the present invention.

[0030] Figure label:

[0031] Current collector 100; Metal layer 110; Composite layer 120;

[0032] Active material layer 200; first coating area 201; second coating area 202; connecting area 203; first main body 210; first connecting part 220; second main body 230; first coating section 231; second coating section 232; mounting groove 233; second connecting part 240;

[0033] Base coat 300; Detailed Implementation

[0034] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0035] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0036] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0037] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0038] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] Composite current collectors are a new type of battery current collector material, which is made by combining polymer materials and metals. Existing composite current collectors have a "sandwich" structure, with an inner polymer layer (such as PET, PP or PI) and two metal conductive layers (such as Al or Cu) on both sides. They have high tensile strength and high elongation, which can restrain cyclic expansion and alleviate electrode breakage.

[0040] In existing technologies, laser cleaning is often used to remove part of the active material layer from the current collector to form a groove for welding the electrode tab to the current collector. However, since the inner layer of the composite current collector is a polymer layer, it is easily burned during laser cleaning, leading to problems such as wrinkling and deformation of the current collector after laser cleaning, which greatly restricts the improvement of electrode yield.

[0041] To address the aforementioned problems, this application proposes an electrode, such as... Figures 1 to 5As shown, the electrode includes a current collector 100 and an active material layer 200. The active material layer 200 is coated on the surface of the current collector 100 and can undergo an electrochemical reaction with the electrolyte. The current collector 100 carries the active material layer 200 and provides a current path. In the prior art, the active material layer of the electrode is often sprayed as a whole by a nozzle. For designs with a centrally located tab, grooves need to be formed on the active material layer by laser cleaning to facilitate the welding of the tab to the current collector. In this design, the active material layer 200 is coated in sections, and the active material is not pre-coated in the tab welding area, forming an exposed area of ​​the current collector 100. This eliminates the need for laser cleaning and groove creation, avoiding damage to the polymer layer caused by laser cleaning, ensuring the flatness of the current collector 100, and improving the electrode yield. In addition, since the electrode in this design does not require laser cleaning after the coating process, manufacturing time and production costs are saved.

[0042] Specifically, such as Figure 2 As shown, the active material layer 200 includes a first coating area 201 and a second coating area 202 disposed along a first direction. The first coating area 201 covers most of the area of ​​the current collector 100, and the area of ​​the second coating area 202 is smaller. The width of the second coating area 202 is similar to the width of the mounting groove 233 for accommodating the tab. The first coating area 201 and the second coating area 202 can be sprayed in stages at different times using the same spray nozzle. For example, after the first coating area 201 is sprayed, the spray nozzle is moved horizontally along the first direction to above the second coating area 202, and then moves relative to the electrode along the second direction to complete the spraying of the second coating area 202. Alternatively, the first coating area 201 and the second coating area 202 can be sprayed simultaneously using different spray nozzles. For example, a first spray nozzle and a second spray nozzle are provided along the first direction, and the first spray nozzle and the second spray nozzle work simultaneously to synchronously form the first coating area 201 and the second coating area 202 on the current collector 100. It is understood that the first spray nozzle and the second spray nozzle can be provided on different nozzles or on the same nozzle. In addition, in the case of... Figure 3 In the embodiment shown, the nozzle is provided with a plurality of first spray nozzles and second spray nozzles arranged alternately along a first direction to form alternating first coating areas 201 and second coating areas 202 on the current collector master roll, thereby forming an electrode master roll. After the coating, drying, rolling and other processes are completed, the electrode master roll is cut into multiple individual electrodes, each individual electrode including a first coating area 201 and a second coating area 202.

[0043] Understandably, during the coating process, the electrode moves relative to the spray nozzle along the second direction, and the coating material sprayed from the nozzle adheres to the surface of the current collector 100. Through the continuous movement of the electrode combined with the spraying from the nozzle, a coating area along the second direction is formed on the current collector 100. It should be noted that during the spraying process, the first coating area 201 is formed by continuous spraying from the nozzle, while the second coating area 202 is formed by intermittent spraying from the nozzle. Thus, along the second direction, the first coating area 201 is continuously provided, and the second coating area 202 is intermittently provided. For ease of description, the two coating areas before and after the interruption of the second coating area 202 are named the first coating segment 231 and the second coating segment 232, respectively. The first coating segment 231 and the second coating segment 232 define the mounting groove 233. It can be understood that since no active material is coated at the mounting groove 233, the current collector 100 is exposed at this point. Thus, the mounting groove 233 can be used to accommodate the electrode tab. The electrode tab is set in the mounting groove 233 and can be welded to the current collector 100 to achieve concentrated current output.

[0044] In some embodiments, such as Figure 2 , Figure 4 and Figure 5 As shown, the active material layer 200 also includes a connecting region 203, which is located between the first coating region 201 and the second coating region 202. The first coating region 201 includes a first main body portion 210, and the second coating region 202 includes a second main body portion 230. The connecting region 203 includes a first connecting portion 220 connected to the first main body portion 210 and a second connecting portion 240 connected to the second main body portion 230. The first connecting portion 220 and the second connecting portion 240 are connected in the connecting region 203. It should be noted that since the sprayed coating is semi-solid and has a certain degree of fluidity, after being sprayed onto the surface of the current collector 100, the coating will naturally flow in all directions. The first main body portion 210 and the first connecting portion 220 are formed by paint sprayed from the same spray nozzle. The first main body portion 210 is the main portion where paint adheres to the first coating area 201, and the first connecting portion 220 is the portion where paint flows and extends to the connecting area 203. Similarly, the second main body portion 230 and the second connecting portion 240 are also formed by paint sprayed from the same spray nozzle. The second main body portion 230 is the main portion where paint adheres to the second coating area 202, and the second connecting portion 240 is the portion where paint flows and extends to the connecting area 203. The presence of the connecting area 203 ensures a smooth transition between the first coating area 201 and the second coating area 202, avoiding the problem of excessive local thickness caused by the overlap of the first coating area 201 and the second coating area 202.

[0045] The width of the transition zone 203 can be adjusted according to actual needs to ensure coating uniformity. It is understood that the thickness of the transition zone 203 is closely related to its width. When the width of the transition zone 203 is wider, the flow range of the paint within the transition zone 203 is larger, resulting in a corresponding decrease in the thickness of the transition zone 203. Conversely, when the width of the transition zone 203 is narrower, the paint flow is restricted, and the first transition portion 220 and the second transition portion 240 press against or stack against each other, thereby increasing the thickness of the transition zone 203.

[0046] Specifically, when the width of the connecting area 203 is greater than a width threshold, the thickness of the connecting area 203 is less than the thickness of the first coating area 201 or the thickness of the second coating area 202. It should be noted that this width threshold is related to various parameters such as spraying parameters, coating characteristics, and the surface condition of the current collector 100, and needs to be determined through specific experiments based on different application scenarios. In this case, such as... Figure 4 As shown, the thickness of the first connecting portion 220 gradually decreases along the direction away from the first main body portion 210, and the thickness of the second connecting portion 240 also gradually decreases along the direction away from the second main body portion 230. Thus, the narrow ends of the first connecting portion 220 and the second connecting portion 240 connect, forming a structure similar to a V-groove. This V-groove structure not only effectively reduces local thickness differences in the coating area but also improves the overall uniformity of the coating, ensuring a uniform distribution of current on the surface of the current collector 100, further optimizing the battery's electrical performance and stability.

[0047] Furthermore, when the width of the connecting area 203 is less than or equal to the width threshold, the thickness of the connecting area 203 will be greater than or equal to the thickness of the first coating area 201, or the thickness of the connecting area 203 will be greater than or equal to the thickness of the second coating area 202. In this case, the flow of paint in the connecting area 203 is restricted, causing the first connecting portion 220 and the second connecting portion 240 to be squeezed or stacked against each other, forming a thicker connecting area 203 (e.g., Figure 5 As shown in the figure, it can be understood that although the thickness of the transition area 203 is thicker than that of the coating area, if the thickness of the transition area 203 is within the allowable deviation range, it will not affect the overall coating performance, because the fluidity of the coating allows the extruded or stacked parts to still transition smoothly, avoiding obvious thickness abrupt changes.

[0048] Furthermore, based on the foregoing, the thickness Y of the transition region 203 and the thickness X1 of the first coating region 201 have the following relationship: 0.95 ≤ Y / X1 ≤ 1.05; and / or, the thickness Y of the transition region 203 and the thickness X2 of the second coating region 202 have the following relationship: 0.95 ≤ Y / X2 ≤ 1.05. Controlling the thickness of the transition region 203 within this range ensures the overall uniformity of the coating and avoids electrical performance fluctuations caused by thickness differences, thereby improving the overall performance of the battery.

[0049] In addition, there are certain limitations on the width of the connecting area 203: along the first direction, the width W of the connecting area 203 has the following relationship: 0mm≤W≤5mm. If the width of the connecting area 203 is too wide, the thickness of the connecting area 203 will be too thin, causing local unevenness of the coating and affecting the current distribution.

[0050] To verify the effectiveness of the above parameter range, the following sets of comparative experiments were conducted. The width W of the connection area 203 was set to 0mm, 1mm, 2mm, 3mm, 4mm, and 5mm, respectively. The ratio of the thickness of the connection area 203 to the thickness of the coating area was 95%, 97%, 98%, 101%, 102%, and 105%, respectively. The mounting groove 233 had uniform specifications, with its length defined as its dimension along the second direction and its width as its dimension along the first direction. The size of the mounting groove 233 was: length * width = 12 * 24mm. Test methods and equipment: At an ambient temperature of 25℃, the width of the connection area 203 was measured using a two-dimensional measuring instrument, and the thickness of the connection area 203 was measured using an offline thickness gauge.

[0051] The specific experimental data are as follows:

[0052]

[0053] As can be seen from the above Examples 1 to 6 and Comparative Examples 1 to 2, when the width of the connecting area 203 satisfies 0≤X≤5mm and the ratio of the thickness of the connecting area 203 to the thickness of the coating area is in the range of 0.95 to 1.05, the production process is normal and the battery cell has good energy density.

[0054] In some embodiments, such as Figure 6 As shown, the current collector 100 includes a composite layer 120 and two metal layers 110, which are respectively connected to both sides of the composite layer 120 to form a sandwich structure. The metal layers 110 are made of conductive metal materials; for example, the metal layer 110 of the positive electrode is generally aluminum foil, while the metal layer 110 of the negative electrode is copper foil. The composite layer 120 is typically made of polymer materials, such as PET, PP, or PI. This composite current collector 100 structure has high tensile strength and high elongation, which can restrain cyclic expansion and alleviate electrode breakage.

[0055] Furthermore, such as Figure 1 As shown, the electrode of this application also includes a base coating 300, which is disposed between the active material layer 200 and the current collector 100 to increase the adhesion between the active material layer 200 and the current collector 100 and prevent peeling. The base coating 300 material is typically selected from materials with good adhesion and chemical stability. Its thickness is controlled at the micrometer level, which does not affect the overall thickness and effectively improves the structural stability of the electrode.

[0056] In some embodiments, to further improve the electrical performance of the electrode, the difference between the areal density A of the first coating region 201 and the areal density B of the second coating region 202 is within 3 mg, wherein the areal density A of the first coating region 201 ranges from 50 mg to 300 mg, and the areal density B of the second coating region 202 ranges from 50 mg to 300 mg. When the difference between the areal density of the first coating region 201 and the areal density of the second coating region 202 is too large, it will lead to uneven electric field distribution inside the electrode, resulting in the risk of lithium plating in the battery cell.

[0057] The difference between the thickness M of the first coating region 201 and the thickness N of the second coating region 202 is within 1 μm. Specifically, the thickness M of the first coating region 201 ranges from 50 μm to 150 μm, and the thickness N of the second coating region 202 also ranges from 50 μm to 150 μm. When the thickness difference between the first coating region 201 and the second coating region 202 is too large, there is a risk of lithium plating in the battery cell.

[0058] Similarly, the thickness difference between the coating area and the bonding area 203 should also be controlled within 1µm to obtain relatively stable electrical performance.

[0059] The second aspect of this application also proposes a battery cell that includes the electrode mentioned in any of the above embodiments. Due to the optimized electrode structure design of this application, the battery cell exhibits higher stability and longer cycle life during charging and discharging.

[0060] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An electrode, characterized in that, include: current collector; An active material layer is coated on the surface of the current collector. The active material layer includes a first coating area and a second coating area disposed along a first direction. The second coating area includes a first coating segment and a second coating segment disposed at intervals along a second direction. A mounting groove for accommodating the tab is defined between the first coating segment and the second coating segment.

2. The electrode sheet according to claim 1, characterized in that, The active material layer further includes a connecting region located between the first coating area and the second coating area. The first coating area includes a first main body portion, and the second coating area includes a second main body portion. The second main body portion includes the first coating segment and the second coating segment disposed at intervals. The connecting region includes a first connecting portion connected to the first main body portion and a second connecting portion connected to the second main body portion. The first connecting portion and the second connecting portion are connected.

3. The electrode sheet according to claim 2, characterized in that, The thickness of the connecting area is less than the thickness of the first coating area or the thickness of the second coating area; In this case, the thickness of the first connecting portion gradually decreases along the direction away from the first main body portion, and the thickness of the second main body portion gradually decreases along the direction away from the second main body portion.

4. The electrode sheet according to claim 2, characterized in that, The thickness of the connecting area is not less than the thickness of the first coating area or the thickness of the second coating area.

5. The electrode sheet according to claim 3 or 4, characterized in that, The thickness Y of the connecting area has the following relationship with the thickness X1 of the first coating area: 0.95≤Y / X1≤1.05; and / or, the thickness Y of the connecting area has the following relationship with the thickness X2 of the second coating area: 0.95≤Y / X2≤1.

05.

6. The electrode sheet according to claim 2, characterized in that, Along the first direction, the width of the connecting area is W, where 0mm≤W≤5mm.

7. The electrode sheet according to claim 1, characterized in that, The current collector includes a composite layer and two metal layers, with the two metal layers respectively connected to both sides of the composite layer.

8. The electrode sheet according to claim 7, characterized in that, The electrode also includes a base coating layer disposed between the active material layer and the current collector.

9. The electrode sheet according to claim 1, characterized in that, The difference between the areal density A of the first coating area and the areal density B of the second coating area is within 3 mg; And / or, the difference between the thickness M of the first coating area and the thickness N of the second coating area is within 1 μm.

10. A battery cell, characterized in that, Including the electrode as described in any one of claims 1 to 9.

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