Pole piece, battery cell and battery
By designing a high-conductivity first active material layer and a low-conductivity second active material layer in the electrode sheet, and accelerating the electrolyte infiltration using the communication holes, the problem of low conductivity of the traditional electrode sheet is solved, and the conductivity performance of the battery cell is significantly improved.
Patent Information
- Application Number
- CN202421121078.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-21
- Publication Date
- 2025-04-04
- Estimated Expiration
- 2034-05-21
AI Technical Summary
The conductivity of traditional double-layer coated electrode sheets is low, resulting in poor conductivity of the battery cell.
An electrode sheet is designed, including a current collector, a first active material layer and a second active material layer. The conductivity of the first active material layer is greater than that of the second active material layer, and extends from the second active material layer to the first active material layer through the communication hole to improve the wetting effect of the electrolyte.
By increasing the conductivity of the first active material layer and optimizing the infiltration path of the electrolyte, the electron and ionic conductivity of the electrode sheet is significantly improved, thereby improving the conductivity of the battery cell.
Smart Images
Figure CN222720441U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of lithium batteries, in particular to a pole piece, a battery core and a battery. Background Art
[0002] Lithium battery refers to a battery containing lithium (including metallic lithium, lithium alloys, lithium ions, and lithium polymers) in the electrochemical system. In recent years, lithium batteries have been widely used in digital products and other fields due to their many advantages such as long cycle life, good safety performance, and rapid charging and discharging.
[0003] Lithium batteries are usually manufactured by assembling positive electrode sheets, negative electrode sheets and separators into battery cells using winding or lamination equipment, and then encapsulating the battery cells in a casing.
[0004] To ensure performance, the double-layer coating technology is currently used to design a multi-layer microstructure for the pole piece, and a double-layer coating is performed on the current collector of the pole piece by configuring slurries with different functional characteristics. However, in the traditional double-layer coated pole piece, the lower slurry on the current collector is a high-density structure, which makes it difficult to transport the electrolyte, and the upper slurry is far away from the current collector, so the electrolyte migrates slowly toward the current collector, and the wetting effect is poor, resulting in low conductivity, which affects the conductive performance of the battery cell. Utility Model Content
[0005] The main purpose of the utility model is to provide a pole piece, aiming to solve the technical problem of low conductivity of the pole piece currently using double-layer coating.
[0006] In order to achieve the above-mentioned purpose, the utility model provides a pole piece, which comprises:
[0007] current collector;
[0008] A first active material layer is disposed on the current collector;
[0009] A second active material layer is disposed on the first active material layer and is located on a side of the first active material layer away from the current collector;
[0010] a connecting hole extending from the second active material layer to the first active material layer;
[0011] The conductivity of the first active material layer is greater than the conductivity of the second active material layer.
[0012] In some embodiments, the first active material layer has a first surface and a second surface that are spaced apart and opposite to each other, the second active material layer has a third surface and a fourth surface that are spaced apart and opposite to each other, the first surface is in contact with the current collector, the third surface is in contact with the second surface, and the connecting hole extends from the fourth surface and passes through the third surface and the second surface in sequence.
[0013] In some embodiments, there is a distance between an end of the communicating hole away from the fourth surface and the first surface.
[0014] In some embodiments, the thickness of at least one of the first active material layer and the second active material layer is greater than the thickness of the current collector; and / or,
[0015] The thickness of the first active material layer is equal to the thickness of the second active material layer.
[0016] In some embodiments, the communicating hole has two side walls that are opposite to each other, and at least one of the two side walls is arranged in a stepped shape.
[0017] In some embodiments, the first active material layer is a coating formed on the current collector, and the second active material layer is coated on the first active material layer; and / or,
[0018] The communicating holes are holes formed by laser etching on the second active material layer and the first active material layer.
[0019] In some embodiments, a plurality of the communicating holes are provided, and the plurality of communicating holes are sequentially spaced apart along the length direction of the second active material layer.
[0020] In some embodiments, the distance between two adjacent communicating holes is 1 mm to 2 mm.
[0021] The utility model also provides a battery cell, which comprises a positive electrode sheet, a negative electrode sheet and a diaphragm, wherein the diaphragm is located between the positive electrode sheet and the negative electrode sheet;
[0022] Wherein, at least one of the positive electrode sheet and the negative electrode sheet adopts the electrode sheet as described above.
[0023] The utility model also provides a battery, which comprises a shell and a battery core arranged in the shell, and the battery core is the battery core as described above.
[0024] The pole piece in the technical solution of the present utility model is a double-layer coated pole piece, which includes a current collector, a first active material layer arranged on the current collector, and a second active material layer arranged on the first active material layer, wherein the conductivity of the first active material layer is greater than the conductivity of the second active material layer, and the process of electrons passing from the first active material layer to the current collector becomes simple, thereby improving the electronic conductivity; and, the connecting hole extends from the second active material layer to the first active material layer, and the electrolyte can pass through the connecting hole and quickly migrate to the first active material layer, thereby improving the wetting effect of the electrolyte and improving the ionic conductivity, thereby improving the conductive performance of the battery cell as a whole. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 This is a schematic diagram of the structure of a pole piece in one embodiment of the utility model;
[0026] Figure 2 This is a schematic diagram of the structure of a pole piece in another embodiment of the utility model;
[0027] Figure 3 It is a schematic diagram of the structure of a pole piece in another embodiment of the utility model.
[0028] Description of Figure Numbers:
[0029] Label name Label name 100 current collector L Connecting hole 200 First active material layer D Electronic Channel 300 Second active material layer
[0030] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION
[0031] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the scheme in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0032] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.
[0033] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.
[0034] In addition, the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.
[0035] To ensure performance, the double-layer coating technology is currently used to design a multi-layer microstructure for the pole piece, and a double-layer coating is performed on the current collector of the pole piece by configuring slurries with different functional characteristics. However, in the traditional double-layer coated pole piece, the lower slurry on the current collector is a high-density structure, which makes it difficult to transport the electrolyte, and the upper slurry is far away from the current collector, so the electrolyte migrates slowly toward the current collector, and the wetting effect is poor, resulting in low conductivity, which affects the conductive performance of the battery cell.
[0036] Based on the technical problems existing in the related prior art mentioned above, the embodiment of the utility model proposes a pole piece to enhance the electrical conductivity and improve the conductive performance of the battery cell.
[0037] Reference Figure 1 The electrode sheet includes: a current collector 100, a first active material layer 200, a second active material layer 300 and a connecting hole L; the first active material layer 200 is arranged on the current collector 100; the second active material layer 300 is arranged on the first active material layer 200 and is located on the side of the first active material layer 200 away from the current collector 100; the connecting hole L extends from the second active material layer 300 to the first active material layer 200; wherein the conductivity of the first active material layer 200 is greater than the conductivity of the second active material layer 300.
[0038] The pole piece of this embodiment is a double-layer coated pole piece, specifically, a double active material layer is arranged on the current collector 100, and the double active material layer includes a first active material layer 200 and a second active material layer 300, the first active material layer 200 is arranged on the current collector 100, and the second active material layer 300 is arranged on the first active material layer 200; in the thickness direction of the pole piece, the current collector 100, the first active material layer 200 and the second active material layer 300 are stacked in sequence. Among them, the pole piece can be a positive pole piece or a negative pole piece, and there is no limitation on this. When the pole piece is a positive pole piece, the current collector 100 can be made of aluminum foil, and the first active material layer 200 and the second active material layer 300 can be made of positive active slurry; when the pole piece is a negative pole piece, the current collector 100 can be made of copper foil, and the first active material layer 200 and the second active material layer 300 can be made of negative active slurry.
[0039] Specifically, the first active material layer 200 and the second active material layer 300 both contain a conductive agent, wherein the conductive agent content in the first active material layer 200 is 0-10%, and the conductive agent content in the second active material layer 300 is 0-8%. Optionally, the conductive agent content X1 in the first active material layer 200 and the conductive agent content X2 in the second active material layer 300 meet the content relationship of 5>(X1-X2) / X2>0.1.
[0040] It is easy to understand that the total content of the conductive agent in the first active material layer 200 and the conductive agent in the second active material layer 300 remains unchanged, so that the conductive agent content in the first active material layer 200 is higher than the conductive agent content in the second active material layer 300. Figure 1 As shown, the conductive agent in the active material layer will squeeze out the electron channel D between the active materials. Therefore, when the content of the conductive agent in the active material layer is high, the number of corresponding electron channels D formed is also relatively large, and the conductivity is also relatively large. That is, in practical applications, the content of the conductive agent in the first active material layer 200 can be increased to increase the number of electron channels D in the first active material layer 200, and then its conductivity, so that the conductivity of the first active material layer 200 is greater than the conductivity of the second active material layer 300. Among them, the conductivity of the first active material layer 200 is greater than the conductivity of the second active material layer 300, and the process of electrons passing from the first active material layer to the current collector becomes simple, thereby improving the electronic conductivity.
[0041] The connecting hole L extends from the second active material layer 300 to the first active material layer 200, that is, the connecting hole L penetrates the second active material layer 300 and is connected to the first active material layer 200. The hole shape and pore size of the connecting hole L can be set according to the actual situation, and there is no limitation on this. In the battery cell, the electrolyte can quickly reach the first active material layer 200 exposed at the bottom of the connecting hole L through the connecting hole L, and then infiltrate the first active material layer 200, thereby improving the infiltration effect of the electrolyte, improving the ionic conductivity, and thus improving the overall conductive performance of the battery cell. Among them, the number of connecting holes L can be set according to the actual situation, and there is no limitation on this.
[0042] In some embodiments, reference Figure 2 The first active material layer 200 has a first surface and a second surface that are arranged opposite to each other at an interval, the second active material layer 300 has a third surface and a fourth surface that are arranged opposite to each other at an interval, the first surface is in contact with the current collector 100, the third surface is in contact with the second surface, and the connecting hole L extends from the fourth surface and passes through the third surface and the second surface in sequence.
[0043] Specifically, in the thickness direction of the electrode sheet, the current collector 100, the first active material layer 200 and the second active material layer 300 are stacked in sequence, the first surface of the first active material layer 200 faces the current collector 100 and contacts the current collector 100, and the third surface of the second active material layer 300 faces the first active material layer 200 and contacts the second surface of the first active material layer 200. In addition, the connecting hole L extends from the fourth surface of the second active material layer 300 and sequentially passes through the third surface of the second active material layer 300 and the second surface of the first active material layer 200, that is, the connecting hole L penetrates the second active material layer 300 and extends into the first active material layer 200. By providing the connecting hole L to extend into the first active material layer 200, the rate at which the electrolyte infiltrates the first active material layer 200 can be further accelerated, the infiltration effect of the electrolyte can be improved, and the ion conductivity can be improved.
[0044] In some embodiments, there is a distance between the end of the connecting hole L away from the fourth surface and the first surface. By setting a distance between the end of the connecting hole L away from the fourth surface of the second active material layer 300 and the first surface of the first active material layer 300, the connecting hole L only extends into the first active material layer 200, rather than penetrating the first active material layer 200. The specific value of the distance can be set according to actual conditions.
[0045] In some embodiments, the thickness of at least one of the first active material layer 200 and the second active material layer 300 is greater than the thickness of the current collector 100; and / or,
[0046] The thickness of the first active material layer 200 is equal to the thickness of the second active material layer 300 .
[0047] In practical applications, the thickness of the first active material layer 200 may be set to be greater than the thickness of the current collector 100, or the thickness of the second active material layer 300 may be set to be greater than the thickness of the current collector 100. In addition, the thickness of the first active material layer 200 and the thickness of the second active material layer 300 may be set to be the same, and the setting is selected according to actual conditions.
[0048] In some embodiments, reference Figure 3, the connecting hole L has two side walls arranged opposite to each other, and at least one of the two side walls is arranged in a stepped shape. Optionally, one side wall of the connecting hole L relative to the two side walls is arranged in a stepped shape, or both the two side walls of the connecting hole L relative to each other are arranged in a stepped shape. The connecting hole L has different apertures at the steps of different heights. Optionally, the connecting hole L can be formed by laser etching, and the laser etching parameters can be adjusted as needed, and the etching depth, etching shape and etching area can be controlled, that is, by controlling and adjusting the etching parameters of the laser, a stepped side wall can be etched in the connecting hole L. Among them, the number of steps of the side wall of the connecting hole L can be set according to actual conditions, and there is no restriction on this. By adopting a stepped setting for the side wall of the connecting hole L, the wetting area of the electrolyte when the connecting hole L infiltrates the first active material layer 200 is increased, thereby improving the wetting effect of the electrolyte and improving the ionic conductivity.
[0049] In some embodiments, the first active material layer 200 is a coating formed on the current collector 100, and the second active material layer 300 is coated on the first active material layer 200; and / or,
[0050] The connecting holes L are holes formed by laser etching in the second active material layer 300 and the first active material layer 200 .
[0051] Among them, the first active material layer 200 can be formed by coating a first slurry on the current collector 100, the first slurry is made by mixing and stirring the first active material, the conductive agent and the binder, and the mass ratio of the first active material, the conductive agent and the binder is: 70-99: 0.1-10: 0.2-10; the second active material layer 300 can be formed by coating a second slurry on the first active material layer 200, the second slurry is made by mixing and stirring the second active material, the conductive agent and the binder, and the mass ratio of the second active material, the conductive agent and the binder is: 70-99: 0.1-8: 0.2-10. Further, the first active material and the second active material can include a mixture of one or more of lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium manganese iron phosphate, sodium iron phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadate, lithium manganate, lithium nickel oxide, lithium nickel cobalt manganate, lithium-rich manganese-based materials, lithium nickel cobalt aluminum oxide, and lithium titanate, including but not limited to this. The conductive agent includes a mixture of one or more of carbon nanotubes, conductive carbon black, acetylene black, graphene, ketjen black, and carbon fibers, including but not limited to these. The binder includes a mixture of one or more of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene-butadiene rubber, including but not limited to these.
[0052] The connecting holes L can be formed by laser etching on the second active material layer 300 and the first active material layer 200. Laser etching is a high-precision processing technology that uses a laser beam to heat, oxidize, evaporate, burn or remove part of the material on the surface of the material to form an image. It has the advantages of fast etching speed, high processing efficiency and high precision.
[0053] In some embodiments, reference Figure 1 , a plurality of connecting holes L are provided, and the plurality of connecting holes L are sequentially spaced along the length direction of the second active material layer 300. Specifically, with the length direction of the second active material layer 300 as a reference direction, the plurality of connecting holes L are sequentially spaced, and there is a set spacing between any two adjacent connecting holes L. The electrolyte can pass through the plurality of connecting holes L provided on the second active material layer 300, and quickly and evenly infiltrate the first active material layer 200, which can improve the infiltration speed and infiltration effect.
[0054] In some embodiments, the spacing between two adjacent connecting holes L is 1 mm to 2 mm. The spacing between two adjacent connecting holes L can be set within the range of 1 mm to 2 mm. For example, the spacing between two adjacent connecting holes L can be set to 1 mm, 1.5 mm or 2 mm. Optionally, the spacing between two adjacent connecting holes L can be set with reference to the electrolyte infiltration requirement. For example, when the electrolyte infiltration requirement is low, the spacing between two adjacent connecting holes L can be set to 1 mm; when the electrolyte infiltration requirement is medium, the spacing between two adjacent connecting holes L can be set to 1.5 mm; when the electrolyte infiltration requirement is high, the spacing between two adjacent connecting holes L can be set to 2 mm. This is only exemplary and not restrictive.
[0055] The embodiment of the utility model further proposes a battery cell, which includes a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is located between the positive electrode sheet and the negative electrode sheet; wherein at least one of the positive electrode sheet and the negative electrode sheet adopts the electrode sheet as described in the above embodiment.
[0056] The specific structure of the pole piece refers to the above embodiment. Since the present battery cell adopts all the technical solutions of all the above embodiments, it at least has all the technical effects brought by the technical solutions of the above embodiments, which will not be described one by one here. Among them, the battery cell can be a wound battery cell or a laminated battery cell.
[0057] The utility model also provides a battery, which includes a housing and a battery cell disposed in the housing, and the battery cell is the battery cell described in the above embodiment. The specific structure of the battery cell refers to the above embodiment. Since the battery adopts all the technical solutions of all the above embodiments, it has at least all the technical effects brought by the technical solutions of the above embodiments, which will not be described one by one here.
[0058] The above description is only a partial or preferred embodiment of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.
Claims
1. A pole piece, characterized in that: include: current collector; A first active material layer is disposed on the current collector; A second active material layer is disposed on the first active material layer and is located on a side of the first active material layer away from the current collector; a connecting hole extending from the second active material layer to the first active material layer; The conductivity of the first active material layer is greater than the conductivity of the second active material layer.
2. The pole piece according to claim 1, characterized in that: The first active material layer has a first surface and a second surface that are arranged opposite to each other at an interval, the second active material layer has a third surface and a fourth surface that are arranged opposite to each other at an interval, the first surface is in contact with the current collector, the third surface is in contact with the second surface, and the connecting hole extends from the fourth surface and passes through the third surface and the second surface in sequence.
3. The pole piece according to claim 2, characterized in that: There is a distance between the end of the communication hole away from the fourth surface and the first surface.
4. The pole piece according to claim 1, characterized in that: The thickness of at least one of the first active material layer and the second active material layer is greater than the thickness of the current collector; and / or, The thickness of the first active material layer is equal to the thickness of the second active material layer.
5. The pole piece according to claim 1, characterized in that: The communicating hole has two side walls which are arranged opposite to each other, and at least one of the two side walls is arranged in a stepped shape.
6. The pole piece according to claim 1, characterized in that: The first active material layer is a coating formed on the current collector, and the second active material layer is coated on the first active material layer; and / or, The communicating holes are holes formed by laser etching on the second active material layer and the first active material layer.
7. The pole piece according to claim 1, characterized in that: A plurality of the communicating holes are provided, and the plurality of communicating holes are sequentially spaced apart along the length direction of the second active material layer.
8. The pole piece according to claim 7, characterized in that: The distance between two adjacent communicating holes is 1 mm to 2 mm.
9. A battery cell, characterized in that: It includes a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is located between the positive electrode sheet and the negative electrode sheet; Wherein, at least one of the positive electrode sheet and the negative electrode sheet is the electrode sheet as described in any one of claims 1-8.
10. A battery, characterized in that: The invention comprises a shell and a battery cell arranged in the shell, wherein the battery cell is the battery cell as claimed in claim 9.