Pole piece and energy conversion device
By setting density variation zones in the active material layer of the electrode, the problem of insufficient kinetic performance in traditional electrode design is solved, thereby improving battery performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-03-24
AI Technical Summary
Traditional electrode designs offer limited improvement in polarization potential perpendicular to the current collector surface, making it difficult to optimize battery dynamics.
Variation zones of the active material layer are set in a direction parallel to the surface of the current collector, including a compaction density variation zone or a surface density variation zone, to optimize the charge exchange performance of the electrode.
By setting a variation zone in the active material layer, the polarization potential of the electrode is reduced, thereby improving the kinetic and cycle performance of the battery.
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Figure CN224036352U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to a battery material technical field, specifically, relates to a pole piece and energy conversion device. BACKGROUND
[0002] The pole piece is a key component in a battery, which is composed of a positive electrode and a negative electrode, and is responsible for the mutual conversion between chemical energy and electrical energy through an electrolyte separator. Traditional pole pieces are mostly single-layer structures, that is, active materials are uniformly coated on the surface of the current collector. In order to improve the kinetics, some pole pieces also have a gradient design in the direction perpendicular to the surface of the current collector, which is generally divided into two layers, that is, the surface layer active material and the inner layer active material are uniformly coated on the surface of the current collector. However, this design can only improve the polarization potential in the direction perpendicular to the surface of the current collector.
[0003] Therefore, the utility model is provided. UTILITY MODEL CONTENT
[0004] The utility model aims to provide a pole piece and an energy conversion device to solve or improve the above technical problems.
[0005] The utility model can be realized as follows:
[0006] In a first aspect, the utility model provides a pole piece, which comprises a current collector and an active material layer arranged on at least one side surface of the current collector.
[0007] In the direction parallel to the surface of the current collector, the active material layer has a change zone, which includes a change zone of the compaction density or a change zone of the area density.
[0008] In an optional embodiment, in the direction parallel to the surface of the current collector, the area density of the active material layer is constant, and the active material layer has a change zone of the compaction density.
[0009] In an optional embodiment, in the direction parallel to the surface of the current collector, the compaction density of the active material layer is constant, and the active material layer has a change zone of the area density.
[0010] In an optional embodiment, the active material layer arranged on the single side surface of the current collector is composed of a plurality of sub-active material layers.
[0011] In the direction parallel to the surface of the current collector, the total area density of the active material layer is constant, and at least part of the sub-active material layers has a change zone of the area density.
[0012] In an optional embodiment, a certain direction in all directions parallel to the surface of the current collector is taken as the x-axis direction, and in the x-axis direction, the change zone exists all the time or partially exists.
[0013] In an optional embodiment, the active material layer arranged on the single side surface of the current collector comprises an inner active material layer and a surface active material layer, both of which have a change region; along the x-axis direction, the change trend of the change region in the inner active material layer is different from that of the change region in the surface active material layer.
[0014] In an optional embodiment, along the x-axis direction, the variable in the change region changes in the form of a linear function, a quadratic function, an exponential function or a piecewise function.
[0015] In an optional embodiment, along the x-axis direction, the variable in the change region changes in a random manner.
[0016] In an optional embodiment, along the direction perpendicular to the surface of the current collector, the active material layer also has a change region.
[0017] In an optional embodiment, the thickness of the current collector is 5-15 μm, and the total thickness of the pole piece is not more than 300 μm.
[0018] In a second aspect, the utility model provides a kind of energy conversion device, including the pole piece of any one of the foregoing embodiments.
[0019] The utility model has the beneficial effects including:
[0020] By arranging the active material layer to have a change region along the direction parallel to the surface of the current collector, the polarization potential in the direction parallel to the surface of the current collector can be optimized, which facilitates reducing the polarization potential of the pole piece as a whole and improving the dynamics of the battery under the condition that the active material layer also has a change region along the direction perpendicular to the surface of the current collector. BRIEF DESCRIPTION OF DRAWINGS
[0021] In order to more clearly illustrate the technical scheme of the embodiments of the utility model, the drawings needed to be used in the embodiments will be simply introduced below, and it should be understood that the following drawings only show some embodiments of the utility model, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.
[0022] Figure 1 The first schematic diagram of the change region in the pole piece provided for the present embodiment;
[0023] Figure 2 The second schematic diagram of the change region in the pole piece provided for the present embodiment;
[0024] Figure 3 The third schematic diagram of the change region in the pole piece provided for the present embodiment;
[0025] Figure 4A fourth schematic view of the varying region in the pole piece provided for the present embodiment;
[0026] Figure 5 A fifth schematic view of the varying region in the pole piece provided for the present embodiment;
[0027] Figure 6 A sixth schematic view of the varying region in the pole piece provided for the present embodiment;
[0028] Figure 7 A schematic view of the structure of the pole piece in Comparative Example 1.
[0029] Legend: 10 - current collector; 20 - active material layer; 21 - inner active material layer; 22 - surface active material layer; 30 - varying region; 40 - non-varying region. DETAILED DESCRIPTION
[0030] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.
[0031] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.
[0032] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.
[0033] In the description of the present application, it should be noted that if the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application.
[0034] In addition, if the terms "first", "second" and the like appear, they are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.
[0035] It should be noted that the features in the embodiments of the utility model can be combined with each other without conflict.
[0036] Embodiment
[0037] The utility model provides a kind of pole piece, which includes current collector 10 and active material layer 20 disposed on at least one side surface of the current collector 10.
[0038] In some embodiments, the active material layer 20 can be disposed only on one side surface of the current collector 10; in other embodiments, the active material layer 20 can be disposed on both side surfaces of the current collector 10.
[0039] In the direction parallel to the surface of the current collector 10, the active material layer 20 has a variation zone 30 (see FIG. 1B for reference). Figures 1 to 6 The variation zone 30 can be a variation zone of the compaction density or a variation zone of the area density (i.e., the variable is the compaction density or the area density).
[0040] For example, in the direction parallel to the surface of the current collector 10, the area density of the active material layer 20 is constant, and the active material layer 20 has a variation zone of the compaction density. Alternatively, in the direction parallel to the surface of the current collector 10, the compaction density of the active material layer 20 is constant, and the active material layer 20 has a variation zone of the area density.
[0041] By setting the active material layer 20 to have a variation zone 30 in the direction parallel to the surface of the current collector 10, the charge exchange impedance of the electrode can be effectively reduced, the polarization potential in the direction parallel to the surface of the current collector 10 can be optimized, and the rate capability and cycle performance of the electrode can be improved. Taking a lithium-ion battery as an example, there are two competing charge transport processes in the pole piece of the lithium-ion battery, which mainly determine the electrochemical performance: on the one hand, the ions in the electrolyte transport in the pores of the pole piece and the separator, and also transport in the solid-phase electrode material particles; on the other hand, the electrons transport through the solid-phase connection of the active material and the conductive agent in the electrode. Generally, an electrode with a good distribution of high porosity exhibits good ion transport characteristics, but the electronic conductivity is poor; and a very dense electrode exhibits poor ion transport characteristics, but has good electronic conductivity. Therefore, by setting the active material layer 20 to have a variation zone 30 in the direction parallel to the surface of the current collector 10, the electrode can have better conductivity and ion transport performance, the charge exchange impedance can be reduced, and the polarization potential in the direction parallel to the surface of the current collector 10 can be optimized, thereby improving the rate capability and cycle performance of the electrode.
[0042] In this embodiment, the active material layers 20 on the same side surface of the current collector 10 can be prepared from the same active slurry or different active slurries.
[0043] For the convenience of understanding, when the active material layers 20 on the same side surface of the current collector 10 are formed by the same active slurry, the active material layers 20 are defined as M active material layers, and the number of the M active material layers can be 1, 2 or more. When the number of the M active material layers is 1, the active material is uniformly coated on the surface of the current collector 10, and the areal density of the active material layer 20 is constant in the direction parallel to the surface of the current collector 10, and the active material layer 20 has a compaction density variation zone. When the number of the M active material layers is n (n≥2), the M active material layers can be composed of M1 sub-active material layers, M2 sub-active material layers, …, and Mn sub-active material layers, and in this case, the compaction density of each sub-active material layer is constant in the direction parallel to the surface of the current collector 10, and at least one sub-active material layer has an areal density variation zone. n
[0044] When the active material layers 20 on the same side surface of the current collector 10 are formed by different active slurries, the active material layers 20 on the single side surface of the current collector 10 are defined as being composed of N1 sub-active material layers, N2 sub-active material layers, …, and Nn sub-active material layers (n≥2), and the compaction density of each sub-active material layer is the same but the areal density is different, or the areal density of each sub-active material layer is the same but the compaction density is different. n
[0045] In some more specific embodiments, when the active material layers 20 on the single side surface of the current collector 10 are composed of a plurality of sub-active material layers, the total areal density of the active material layers 20 is constant in the direction parallel to the surface of the current collector 10, and at least part of the sub-active material layers has an areal density variation zone.
[0046] In some embodiments, the variation zone 30 can include all regions of the active material layer 20, and in other embodiments, the variation zone 30 can only include part of the regions of the active material layer 20, and in this case, it can be understood that the active material layer 20 includes the variation zone 30 and a non-variation zone 40. It can also be understood that a certain direction in all directions parallel to the surface of the current collector 10 is taken as the x-axis direction, and the variation zone 30 exists all the time or partially exists in the x-axis direction.
[0047] In this embodiment, the variation trend of the variation zone 30 is not limited, and it can be regular variation or irregular variation.
[0048] In some alternative embodiments, the variable (areal density or compaction density) in the change zone 30 can vary as a linear function along the x-axis direction. In other alternative embodiments, the variable in the change zone 30 can vary as a quadratic function along the x-axis direction. In other alternative embodiments, the variable in the change zone 30 can vary exponentially along the x-axis direction. In other alternative embodiments, the variable in the change zone 30 can vary as a piecewise function along the x-axis direction.
[0049] Taking the active material layer 20 on the single side surface of the current collector 10 as an example, the active material layer 20 includes two sub-active material layers, which are referred to as the inner layer active material layer 21 and the surface layer active material layer 22 according to the distance from the surface of the current collector 10. Both the inner layer active material layer 21 and the surface layer active material layer 22 have change zones 30. Along the x-axis direction, the change trend of the change zone 30 in the inner layer active material layer 21 is different from that of the change zone 30 in the surface layer active material layer 22. In the front view, the intersection point of the left side surface of the current collector 10 and the lower surface of the current collector and the front surface of the current collector is taken as the origin of the x-axis, and the value of x represents the position in the sub-active material layer with a distance of x from the origin of the x-axis, and y represents the areal density corresponding to the position in the sub-active material layer with a distance of x from the origin of the x-axis.
[0050] Referring to Figure 1 , along the x-axis direction parallel to the surface of the current collector 10, the areal density of the inner layer active material layer 21 gradually decreases all the time, and the areal density of the surface layer active material layer 22 gradually increases all the time. For example, Figure 2 , along the x-axis direction parallel to the surface of the current collector 10, the areal density of the inner layer active material layer 21 gradually decreases to 0 and then remains unchanged at 0, and the areal density of the surface layer active material layer 22 gradually increases to the highest value and then remains unchanged at the highest value (the unchanged region in the surface layer active material layer 22 is a non-change zone 40). For example, Figure 3 , along the x-axis direction parallel to the surface of the current collector 10, the areal density of the inner layer active material layer 21 remains unchanged first (the unchanged region in the inner layer active material layer 21 is a non-change zone 40), then gradually decreases to 0, and finally remains unchanged at 0, and the areal density of the surface layer active material layer 22 is 0 first, then gradually increases to the highest value, and finally remains unchanged at the highest value (the unchanged region in the surface layer active material layer 22 is a non-change zone 40). For example, Figure 4 , along the x-axis direction parallel to the surface of the current collector 10, the areal density of the inner layer active material layer 21 has a change trend of rapidly decreasing first, then slowly decreasing, and then rapidly decreasing again, and the areal density of the surface layer active material layer 22 has a change trend of rapidly increasing first, then slowly increasing, and then rapidly increasing again. For example, Figure 5In the x-axis direction parallel to the surface of the current collector 10, the surface density of the inner active material layer 21 decreases first and then remains unchanged (the region of the inner active material layer 21 that remains unchanged is a non-change region 40), and the surface density of the surface active material layer 22 increases first and then remains unchanged (the region of the surface active material layer 22 that remains unchanged is a non-change region 40). For example, Figure 6 In the x-axis direction parallel to the surface of the current collector 10, the surface density of the inner active material layer 21 decreases slowly first, then decreases rapidly, and then decreases slowly again; and the surface density of the surface active material layer 22 increases slowly first, then increases rapidly, and then increases slowly again.
[0051] In addition, in the direction perpendicular to the surface of the current collector 10, the active material layer 20 also has a change region 30.
[0052] By arranging the change region 30 in the direction perpendicular to the surface of the current collector 10 and in the direction parallel to the surface of the current collector 10, the polarization potential of the entire pole piece can be reduced, and the kinetics of the battery can be improved.
[0053] In some optional embodiments, the thickness of the current collector 10 can be 5 μm to 15 μm, such as 5 μm, 8 μm, 10 μm, 12 μm, or 15 μm, or other values within the range of 5 μm to 15 μm.
[0054] In some optional embodiments, the total thickness of the pole piece is not more than 300 μm. When the pole piece is a lithium ion battery negative pole piece, the thickness can exemplarily be 50 μm to 200 μm; when the pole piece is a lithium ion battery positive pole piece, the thickness can exemplarily be 90 μm to 280 μm; when the pole piece is a supercapacitor pole piece, the thickness can exemplarily be 20 μm to 200 μm; when the pole piece is a sodium ion battery or a zinc ion battery pole piece, the thickness can exemplarily be 50 μm to 250 μm.
[0055] In addition, the present embodiment also provides an energy conversion device, which comprises the pole piece of any one of the foregoing embodiments.
[0056] Exemplarily, the energy conversion device can comprise a battery (such as a sodium ion battery, a lithium ion battery, a zinc ion battery, etc.), a capacitor, a solar cell, or the like.
[0057] Application Example 1
[0058] The present application example provides a lithium ion battery negative double-layer pole piece, and a preparation method thereof is as follows:
[0059] (1) Preparation of surface active material slurry: mixing secondary particle graphite, single particle graphite, conductive carbon black, carboxymethyl cellulose and butadiene-styrene rubber in a mass ratio of 77.6:19.4:0.4:1.2:1.4 to obtain a surface active material slurry with a viscosity of about 3500 cp and a solid content of about 50 wt%;
[0060] Preparation of inner active material slurry: mixing secondary particle graphite, single particle graphite, conductive carbon black, carboxymethyl cellulose and butadiene-styrene rubber in a mass ratio of 19.3:77.2:0.6:1.1:1.8 to obtain an inner active material slurry with a viscosity of about 3000 cp and a solid content of about 49 wt%;
[0061] (2) Using a double-layer coating method, the two layers of slurry are simultaneously coated on one side surface of the copper current collector 10, and the surface density is adjusted by controlling the opening size of the spray nozzle, so that the surface density of the surface active material layer 22 is y1=60-20x, and the surface density of the inner active material layer 21 is y2=40+20x, and the total surface density on one side is y=100 g / cm 2 ;
[0062] (3) The other side of the copper current collector 10 is coated in the same way, and the total surface density on both sides is 200 g / cm 2 ;
[0063] (4) Rolling is performed to obtain a lithium ion battery negative plate (the thickness of the copper current collector 10 is 6 μm, and the total thickness of the lithium ion battery negative plate is 135 μm) having a variation zone 30 parallel to the surface of the current collector 10;
[0064] (5) Using the plate, a lithium ion battery is prepared, denoted as a1.
[0065] Application Example 2
[0066] The difference between this application example and application example 1 is that the surface density of the surface active material layer 22 is y1=60-60x, and the surface density of the inner active material layer 21 is y2=40+60x, and the total surface density on one side is y=100 g / cm 2 .
[0067] The lithium ion battery obtained in this application example is denoted as a2.
[0068] Application Example 3
[0069] The difference between this application example and application example 1 is that the surface density of the surface active material layer 22 is y1=100-125x (0≤x≤0.8) and y1=0 (0.8≤x≤1.0), and the surface density of the inner active material layer 21 is y2=125x (0≤x≤0.8) and y2=100 (0.8≤x≤1.0).
[0070] The lithium ion battery obtained in the application example is denoted as a3.
[0071] Application Example 4
[0072] The application example is different from the application example 1 in that the surface density y1 of the surface active material layer 22 is 60-10x-10(1-x) 2 , and the surface density y2 of the inner active material layer 21 is 640+10x+10(1-x) 2 .
[0073] The lithium ion battery obtained in the application example is denoted as a4.
[0074] Application Example 5
[0075] The application example is different from the application example 1 in that the surface density y1 of the surface active material layer 22 is 60-10(2-2 x ), and the surface density y2 of the inner active material layer 21 is 40+10(2-2 x ).
[0076] The lithium ion battery obtained in the application example is denoted as a5.
[0077] Comparative Example 1
[0078] The comparative example provides a lithium ion battery negative electrode double-layer electrode (such as Figure 7 ), and the preparation method is as follows:
[0079] (1) prepare surface negative electrode slurry and inner negative electrode slurry;
[0080] (2) using a wet double-layer spraying method, the two layers of slurry are simultaneously coated on one side surface of the copper current collector 10, the total surface density y of one side is 100 g / cm 2 , the surface density y1 of the surface active material layer 22 is the surface density y2 of the inner active material layer 21, which is 50 g / cm 2 .
[0081] (3) spray the other side of the copper current collector 10 in the same way, and the total surface density of the two sides is 200 g / cm 2 ;
[0082] (4) roll to obtain a lithium ion battery negative electrode sheet which does not have a change area 30 in the direction parallel to the surface of the current collector 10 but has a change area 30 in the direction perpendicular to the surface of the current collector 10;
[0083] (5) using the electrode sheet, a lithium ion battery is prepared, denoted as b1.
[0084] Comparative Example 2
[0085] The difference between the present comparative example and Comparative Example 1 is that the single-sided total area density y = 100 g / cm 2 The surface density of the surface active material layer 22 is y1 = 60, and the surface density of the inner active material layer 21 is y2 = 40 g / cm 2 .
[0086] The pole piece obtained in the present comparative example also has no variation region 30 in the direction parallel to the surface of the current collector 10, but has a variation region 30 in the direction perpendicular to the surface of the current collector 10.
[0087] The lithium ion battery obtained in the present comparative example is denoted as b2.
[0088] Comparative Example 3
[0089] The difference between the present comparative example and Comparative Example 1 is that the single-sided total area density y = 100 g / cm 2 .
[0090] The pole piece obtained in the present comparative example has no variation region 30 in either the direction parallel to the surface of the current collector 10 or the direction perpendicular to the surface of the current collector 10.
[0091] The lithium ion battery obtained in the present comparative example is denoted as b3.
[0092] Test Example
[0093] The thickness of the pole piece in the above application examples 1-5 and comparative examples 1-3, and the process and conditions for further preparing the battery from the pole piece are all consistent. The batteries prepared in the above application examples 1-5 and comparative examples 1-3 are tested for direct current resistance (DCR), and the results are shown in Table 1.
[0094] Table 1 Test Results
[0095]
[0096] In summary, by arranging the active material layer 20 to have a variation region 30 in the direction parallel to the surface of the current collector 10, the polarization potential in the direction parallel to the surface of the current collector 10 can be optimized, which is conducive to reducing the overall polarization potential of the pole piece and improving the kinetics of the battery under the condition that the direction perpendicular to the surface of the current collector 10 also has a variation region 30.
[0097] The above is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.
Claims
1. An electrode sheet, characterized in that, The electrode includes a current collector and an active material layer disposed on at least one side surface of the current collector; Along a direction parallel to the surface of the current collector, the active material layer has a variation zone, which includes a compaction density variation zone or an areal density variation zone.
2. The electrode sheet according to claim 1, characterized in that, Along a direction parallel to the surface of the current collector, the areal density of the active material layer remains constant, and the active material layer has a compaction density variation zone.
3. The electrode sheet according to claim 1, characterized in that, Along a direction parallel to the surface of the current collector, the compaction density of the active material layer remains constant, and the active material layer has a region of varying areal density.
4. The electrode sheet according to claim 3, characterized in that, The active material layer disposed on one side surface of the current collector is composed of multiple sub-active material layers; Along a direction parallel to the surface of the current collector, the total areal density of the active material layer remains constant, while at least a portion of the active material layer has an areal density variation region.
5. The electrode sheet according to any one of claims 1 to 4, characterized in that, Take one of the directions parallel to the surface of the current collector as the x-axis direction. Along the x-axis direction, the change zone always exists or partially exists.
6. The electrode sheet according to claim 5, characterized in that, The active material layer disposed on one side surface of the current collector includes an inner active material layer and a surface active material layer, both of which have variation zones. Along the x-axis, the variation trend of the variation region in the inner active material layer is different from that in the surface active material layer.
7. The electrode sheet according to claim 5, characterized in that, Along the x-axis, the variables in the change region change in a linear, quadratic, exponential, or piecewise manner; or, along the x-axis, the variables in the change region change in an irregular manner.
8. The electrode sheet according to claim 1, characterized in that, The active material layer also has a variation zone along a direction perpendicular to the surface of the current collector.
9. The electrode sheet according to claim 1, characterized in that, The thickness of the current collector is 5μm to 15μm, and the total thickness of the electrode does not exceed 300μm.
10. An energy conversion device, characterized in that, Includes the electrode sheet as described in any one of claims 1 to 9.