Pole piece and battery
By designing a regional structure with decreasing density of active materials on the pole sheet, the problem of uneven distribution of SOC after battery charging is solved, and the uniform distribution of current density and SOC in each area of the pole sheet is achieved, thereby improving the battery performance and service life.
Patent Information
- Application Number
- CN202420230944.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-30
- Publication Date
- 2025-02-11
- Estimated Expiration
- 2034-01-30
AI Technical Summary
After charging, there is a problem of uneven distribution of residual power (SOC) in the battery, resulting in poor performance of the battery and shortening its service life.
A pole sheet is designed, with the density of active material decreasing in the direction from the pole ear to the pole sheet body, forming at least two areas: the first area close to the pole ear is greater than the second area far away from the pole ear, through the roller Pressure technology adjusts the thickness and density of the active material.
By making the impedance of each area of the pole sheet uneven, the current density uneven phenomenon caused by the bus current effect of the pole sheet is evenly distributed, thereby improving battery performance and extending service life.
Smart Images
Figure CN222462930U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of batteries, in particular to a pole piece and a battery. Background Art
[0002] In recent years, batteries have been widely used in smart phones, tablet computers, smart wearables, power tools, electric vehicles, etc. With the widespread use of batteries, consumers have put forward higher requirements for battery performance, service life and safety.
[0003] At present, there is a problem of uneven distribution of remaining capacity (SOC) after charging the battery, that is, the remaining capacity in different areas of the electrode is different after charging for a certain period of time, which will affect the performance of the battery and shorten the battery life. Utility Model Content
[0004] A series of simplified concepts are introduced in the utility model content section, which will be further described in detail in the detailed implementation section. The utility model content section of the utility model does not mean to attempt to define the key features and essential technical features of the technical solution claimed for protection, nor does it mean to attempt to determine the scope of protection of the technical solution claimed for protection.
[0005] The utility model provides a pole piece, comprising a pole piece body and at least one pole ear connected to the pole piece body, the pole piece body comprising a current collector and an active material coated on the surface of the current collector, the pole piece body comprising at least two regions in a direction from close to the pole ear to away from the pole ear, wherein the density of the active material in a first region close to the pole ear is greater than the density of the active material in a second region away from the pole ear.
[0006] Exemplarily, the pole ear includes a positive pole ear and a negative pole ear respectively connected to two ends of the pole piece body, the first area includes edge areas close to the two ends of the pole piece body, and the second area includes the middle area of the pole piece body.
[0007] Exemplarily, with the direction from close to the electrode lug to far from the electrode lug as the first direction, the density of the active material decreases along the first direction.
[0008] Exemplarily, the density of the active material decreases linearly along the first direction; and / or
[0009] The density of the active material decreases stepwise along the first direction.
[0010] Illustratively, the density of the active material includes area density and / or compacted density.
[0011] Exemplarily, before rolling, the thickness of the active material in the first region is different from the thickness of the active material in the second region; after rolling, the thickness of the active material in the first region is the same as the thickness of the active material in the second region.
[0012] Exemplarily, the active material is coated on both side surfaces of the current collector, wherein the active material is non-uniformly coated on the first surface of the current collector and / or the second surface of the current collector.
[0013] Exemplarily, when power is turned on, the impedance of the first region is greater than the impedance of the second region.
[0014] Exemplarily, the electrode sheet includes a positive electrode sheet or a negative electrode sheet.
[0015] The utility model also provides a battery, comprising any one of the pole pieces described above.
[0016] According to the pole piece and battery provided by the utility model, the density of the active material in the area close to the pole ear is made greater than the density of the active material in the area far from the pole ear, so that the impedance of the area close to the pole ear is greater than the impedance of the area far from the pole ear, thereby offsetting the phenomenon that the current density in the area close to the pole ear is greater than the current density in the area far from the pole ear caused by the pole ear convergence effect, so that the current density of each area of the pole piece is equivalent, and the remaining charge (SOC) of each area of the pole piece is evenly distributed, so as to improve the performance of the battery and extend the service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The following drawings of the present invention are used as a part of the present invention for understanding the present invention. The drawings show the embodiments of the present invention and their descriptions, and are used to explain the principle of the present invention.
[0018] In the attached figure:
[0019] Figure 1 A schematic diagram showing a non-uniform distribution of the remaining charge (SOC) of a battery;
[0020] Figures 2A-2D A schematic diagram of coating of active materials before rolling according to an embodiment of the utility model is shown;
[0021] Figure 3 It shows a schematic structural diagram of a rolled rear pole piece according to an embodiment of the utility model;
[0022] Figure 4 A comparison diagram of the remaining capacity (SOC) of a battery according to an embodiment of the utility model and a non-uniformly distributed remaining capacity (SOC) is shown.
[0023] Reference numerals
[0024] 10. Pole body 20. Pole ear
[0025] 30. Current collector 40. Active material
[0026] 51. First edge region 52. Second edge region
[0027] 60. Middle Area DETAILED DESCRIPTION
[0028] In the following description, a large number of specific details are given to provide a more thorough understanding of the utility model. However, it is obvious to those skilled in the art that the utility model can be implemented without one or more of these details. In other examples, in order to avoid confusion with the utility model, some technical features known in the art are not described.
[0029] In order to thoroughly understand the present invention, a detailed description will be provided in the following description to illustrate the pole piece and battery of the present invention. Obviously, the implementation of the present invention is not limited to the specific details familiar to technicians in the field of battery technology. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention can also have other embodiments.
[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the utility model. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of the features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.
[0031] Now, exemplary embodiments according to the present utility model will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in a variety of different forms and should not be interpreted as being limited to the embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of the present utility model thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art. In the accompanying drawings, for the sake of clarity, the thickness of layers and regions is exaggerated, and the same reference numerals are used to represent the same elements, and thus their description will be omitted.
[0032] In the existing battery pole piece, the active material (i.e., the dressing) is usually evenly coated on the current collector. However, after the battery is charged, there is a problem of uneven distribution of the remaining charge (SOC), such as Figure 1As shown in the figure, the remaining charge (SOC) in different areas of the pole piece is different. After analysis, it is found that this is caused by the current confluence effect in the area close to the pole ear. Figure 1 In the example shown, two pole ears connected to the pole piece body are respectively provided at both ends of the pole piece, usually a positive pole ear and a negative pole ear. Therefore, during the charging process, a confluence effect is generated at both ends of the pole piece, and the current density at both ends of the pole piece is greater than that in the middle area. After the same charging time, the remaining power (SOC) in the areas at both ends of the pole piece must be greater than the remaining power in the middle area, thereby affecting the battery performance and shortening the battery life.
[0033] In view of the above problems, the utility model provides a pole piece, such as Figures 2A-2D and Figure 3 As shown, it includes a pole piece body 10 and at least one pole ear 20 connected to the pole piece body 10, the pole piece body 10 includes a current collector 30 and an active material 40 coated on the surface of the current collector 30, and the pole piece body 10 includes at least two regions in a direction from close to the pole ear 20 to away from the pole ear 20, wherein the density of the active material in the first region close to the pole ear is greater than the density of the active material in the second region away from the pole ear.
[0034] In one embodiment, the electrode sheet is a positive electrode sheet. Taking a lithium-ion battery as an example, the electrode sheet body 10 of the positive electrode sheet of a lithium-ion battery is usually evenly mixed with a positive electrode active material (such as lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, etc.) and a conductive agent (such as acetylene black, conductive graphite, furnace black, etc.) and a binder (such as polyvinylidene fluoride, sodium carboxymethyl cellulose and styrene-butadiene rubber), stirred into a paste slurry, and evenly coated on both sides of the positive electrode collector. Dry under nitrogen flow to remove the organic dispersant, then press it into shape with a roller press, and then cut it into a specified size according to design requirements. The tabs of the positive electrode sheet are led out from the positive electrode collector, and the tabs of the positive electrode sheet are usually made of aluminum foil.
[0035] In one embodiment, the electrode sheet is a negative electrode sheet. The negative electrode active material of the negative electrode sheet of the lithium-ion battery mainly includes graphite or lithium titanate, and the negative electrode current collector can be made of copper foil. The preparation process of the negative electrode sheet is roughly the same as that of the positive electrode sheet, which will not be repeated here. The tab of the negative electrode sheet is led out from the negative electrode current collector, and the tab of the negative electrode sheet is usually made of copper foil.
[0036] Exemplarily, the pole ear 20 includes a positive pole ear and a negative pole ear respectively connected to two ends of the pole piece body 10, the first area includes edge areas close to the two ends of the pole piece body, and the second area includes the middle area of the pole piece body.
[0037] In one embodiment, Figure 3As shown, the pole piece includes a pole piece body 10 and two pole ears 20 connected to the pole piece body 10, the two pole ears 20 are usually a positive pole ear and a negative pole ear, and the two are arranged oppositely at two ends of the pole piece body 10. It should be noted that the number of pole ears 20 connected to the pole piece body 10 can be set as needed, such as one, two or more, and the present application does not limit this.
[0038] In one embodiment, Figure 2A and Figure 3 As shown, the two ends of the pole piece body 10 are respectively a first edge region 51 connected to one pole lug and a second edge region 52 connected to the other pole lug. The first edge region 51 and the second edge region 52 are both used as the first region close to the pole lug, and the middle region 60 between the first edge region 51 and the second edge region 52 is used as the second region away from the pole lug. It should be noted that the number of regions divided into the pole piece body 10 can be set as needed. When the number of pole lugs 20 connected to the pole piece body 10 is N, the pole piece body 10 is divided into at least N+1 regions, wherein at least one region close to the pole lug 20 is used as the first region, and at least one region away from the pole lug 20 is used as the second region.
[0039] Exemplarily, the density of the active material decreases along the first direction from close to the electrode lug to far from the electrode lug, wherein the density of the active material decreases linearly along the first direction; and / or the density of the active material decreases stepwise along the first direction.
[0040] In one embodiment, when the pole piece body 10 is connected to only one pole lug, the first direction is the direction from the first end close to the pole lug to the second end away from the pole lug. When the pole piece body 10 is connected to two oppositely disposed pole lugs 20, the first direction includes the direction from the first end close to the pole lug to the middle area away from the pole lug, and also includes the direction from the second end close to the pole lug to the middle area away from the pole lug, that is, the first direction includes the direction from the edge to the center of the pole piece body 10.
[0041] In one embodiment, Figure 2A As shown, the density of the active material decreases stepwise along the first direction. When the density of the active material decreases stepwise along the first direction, the density distribution of the active material in a single area of the pole piece body 10 is uniform, while the density of the active material in two adjacent areas is different. The density of the active material includes the surface density and / or the compaction density.
[0042] In one embodiment, Figure 2BAs shown, the density of the active material decreases linearly along the first direction. When the density of the active material decreases linearly along the first direction, no matter how many regions the pole piece body 10 is divided into, the density distribution of the active material in the region is non-uniform. The density of the active material includes surface density and / or compaction density.
[0043] It should be noted that the density of the active material decreases along the first direction in a manner that is a combination of linear decrease and stepwise decrease or other decrease methods, and the present application does not impose any limitation on this.
[0044] Exemplarily, the active material 40 is coated on both side surfaces of the current collector 30 , wherein the active material 40 is non-uniformly coated on the first surface of the current collector 30 and / or the second surface of the current collector.
[0045] In one embodiment, since the active material 40 is coated on the surfaces of both sides of the current collector 30 , the non-uniform coating of the active material includes single-side non-uniform coating or double-side non-uniform coating. Figure 2C The case of double-sided non-uniform coating is shown. By making the density of the active material 40 on both sides of the current collector 30 different, it can be achieved that the density of the active material in the first region is greater than the density of the active material in the second region. Figure 2D The case of single-sided non-uniform coating is shown, the density of the active material 40 on one side of the current collector 30 is different, and the density of the active material 40 on the other side is the same, and the density of the active material in the first region can also be greater than the density of the active material in the second region. Whether the active material is coated on one side or on both sides can be set as needed, and this application does not limit this.
[0046] Exemplarily, before rolling, the thickness of the active material in the first region is different from the thickness of the active material in the second region; after rolling, the thickness of the active material in the first region is the same as the thickness of the active material in the second region.
[0047] In one embodiment, Figures 2A-2D shows the coating of the active material 40 on the surface of the current collector 30 before rolling. Figure 3 shows the coating of the active material 40 on the surface of the current collector 30 after rolling.
[0048] Before rolling, the thickness of the active material 40 in each region of the pole piece body 10 is different. After rolling, the thickness of the active material in each region is the same but the density is different. Generally, the density of the active material after rolling is proportional to the thickness of the active material before rolling, and the density distribution of the active material after rolling is proportional to the thickness distribution of the active material before rolling. For example, when the thickness of the active material in the first region before rolling is twice the thickness of the active material in the second region, the thickness of the active material in the first region after rolling is equal to the thickness of the active material in the second region, the surface density of the active material in the first region is twice the surface density of the active material in the second region, and the compaction density of the active material in the first region is also twice the compaction density of the active material in the second region.
[0049] In one embodiment, Figure 2A As shown, before rolling, the thickness of the active material 40 in the first edge region 51 is H1, the thickness of the active material 40 in the middle region 60 is H2, and the thickness of the active material 40 in the second edge region 52 is H3. After rolling, as shown in FIG. Figure 3 As shown, the thickness of the active material 40 in the first edge region 51 , the second edge region 52 , and the middle region 60 is H. The method for designing the density of each area of the electrode body 10 while ensuring that the capacity of the battery cell remains unchanged is as follows: the total length of the electrode body 10 is known to be L, and the average surface density of the electrode body 10 is M or the average compaction density Y according to the battery cell capacity. When the length of the first edge area 51 of the electrode body 10 is L1, the surface density is M1 or the compaction density is Y1 (M1=Y1×H), and the length of the middle area 60 is L2, the surface density is M2 or the compaction density is Y2 (M2=Y2×H), the length L3=L-L1-L2 of the remaining second edge area 52 can be obtained, and the average surface density M3=(L×M-L1×M1+L2×M2) / (L-L1-L2) of the second edge area 52, or the average compaction density Y3=(L×Y-L1×Y1+L2×Y2) / (L-L1-L2) of the second edge area 52 can be obtained.
[0050] Exemplarily, when power is turned on, the impedance of the first region is greater than the impedance of the second region.
[0051] In one embodiment, the lug confluence effect causes the current density of the first region near the lug to be greater than the current density of the second region away from the lug. By making the density of the active material in the first region near the lug greater than the density of the active material in the second region away from the lug, the impedance of the first region near the lug is greater than the impedance of the second region away from the lug, the current density of the second region with large impedance is reduced and the current density of the first region with small impedance is increased, thereby offsetting the lug confluence effect, making the current density of each region of the pole piece roughly the same, so that the remaining charge (SOC) of each region of the pole piece after charging for the same time is also roughly the same. In addition, since the electrolyte infiltration effect of the high-density region of the active material is not as good as the electrolyte infiltration effect of the low-density region of the active material, it further helps to reduce the current density of the high-density region of the active material and increase the current density of the low-density region of the active material.
[0052] In one embodiment, Figure 4 As shown, curve 1 shows the remaining charge (SOC) distribution of the electrode sheet with uniform coating of active material, and curve 2 shows the remaining charge (SOC) distribution of the electrode sheet with uneven coating of active material. By making the density of active material in different areas different, the distribution of the remaining charge (SOC) of the electrode sheet is significantly improved, making the distribution of SOC more uniform, thereby improving the performance of the battery and extending the service life of the battery.
[0053] The utility model also provides a battery, comprising a positive electrode sheet, a negative electrode sheet and a separator, wherein the positive electrode sheets and the negative electrode sheets are arranged alternately, the separator is arranged between the positive electrode sheets and the negative electrode sheets, and the positive electrode sheets and / or the negative electrode sheets are the electrode sheets as described above.
[0054] According to the pole piece and battery provided by the utility model, the density of the active material in the area close to the pole ear is made greater than the density of the active material in the area far from the pole ear, so that the impedance of the area close to the pole ear is greater than the impedance of the area far from the pole ear, thereby offsetting the phenomenon that the current density in the area close to the pole ear is greater than the current density in the area far from the pole ear caused by the pole ear convergence effect, so that the current density of each area of the pole piece is equivalent, and the remaining charge (SOC) of each area of the pole piece is evenly distributed, so as to improve the performance of the battery and extend the service life of the battery.
[0055] The utility model has been described through the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the utility model to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the utility model is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the utility model, and these variations and modifications all fall within the scope of protection claimed by the utility model. The protection scope of the utility model is defined by the attached claims and their equivalents.
Claims
1. A pole piece, characterized in that: The invention comprises a pole piece body and at least one pole ear connected to the pole piece body, wherein the pole piece body comprises a current collector and an active material coated on the surface of the current collector, and the pole piece body comprises at least two regions in a direction from close to the pole ear to away from the pole ear, wherein the density of the active material in the first region close to the pole ear is greater than the density of the active material in the second region away from the pole ear.
2. The pole piece according to claim 1, characterized in that: When there are multiple pole ears, the multiple pole ears include a positive pole ear and a negative pole ear respectively connected to the two ends opposite to the pole piece body, the first area includes the edge area close to the two ends of the pole piece body, and the second area includes the middle area of the pole piece body.
3. The pole piece according to claim 1, characterized in that: Taking a direction from close to the electrode tab to far from the electrode tab as a first direction, the density of the active material decreases along the first direction.
4. The pole piece according to claim 3, characterized in that: The density of the active material decreases linearly along the first direction; and / or The density of the active material decreases stepwise along the first direction.
5. The pole piece according to claim 1, characterized in that: The density of the active material includes area density and / or compacted density.
6. The pole piece according to claim 1, characterized in that: Before rolling, the thickness of the active material in the first region is different from the thickness of the active material in the second region; After rolling, the thickness of the active material in the first region is the same as the thickness of the active material in the second region.
7. The pole piece according to claim 1, characterized in that: The active material is coated on a first surface and a second surface on both sides of the current collector, wherein the active material is non-uniformly coated on the first surface of the current collector and / or the second surface of the current collector.
8. The pole piece according to claim 1, characterized in that: When powered on, the impedance of the first region is greater than the impedance of the second region.
9. The pole piece according to claim 1, characterized in that: The electrode sheet includes a positive electrode sheet or a negative electrode sheet.
10. A battery, characterized in that: A pole piece comprising any one of claims 1 to 9.