Negative pole piece, battery cell and battery
By setting coatings of different heights on the current collector surface of the negative electrode sheet, the problem that the electrolyte cannot enter the thick electrode quickly is solved, the energy density and safety of the lithium battery are improved, and the rapid transmission of lithium ions is achieved.
Patent Information
- Application Number
- CN202420058843.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-09
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2034-01-09
AI Technical Summary
The electrolyte cannot enter quickly in thick electrode lithium-ion batteries, resulting in lithium extraction problems and safety hazards, and insufficient energy density.
The first coating and the second coating of different heights are provided on the current collector surface of the negative electrode sheet to improve the storage space of the electrolyte and the lithium ion diffusion path, ensuring that the electrolyte and lithium ions quickly enter the interior of the electrode sheet.
It improves the energy density of lithium batteries, shortens the lithium ion transmission path, reduces the risk of lithium excretion, and enhances the safety and stability of the battery.
Smart Images
Figure CN222190789U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of lithium ion batteries, in particular to a negative electrode sheet, a battery core and a battery. Background Art
[0002] With the increasing number of electronic products, the use of lithium-ion batteries is also increasing. Lithium-ion batteries have the advantages of high energy density, long cycle life, low pollution, and recyclability. They have become the energy core of most electronic products, and users' demand for lithium-ion battery performance is also increasing. For example, in order to extend the use time of electronic products, the energy density of batteries is constantly increasing.
[0003] There are many ways to increase the energy density of batteries. Currently, the most effective way to increase the energy density is to increase the thickness of the electrode, that is, to use thick electrodes. However, thick electrodes have a long lithium ion transmission path, and the electrolyte cannot quickly enter the electrode. Long-term use can easily lead to lithium deposition, which poses a serious safety hazard. Utility Model Content
[0004] In order to achieve the above-mentioned purpose, the utility model proposes a negative electrode plate, which aims to solve the technical problem that the electrolyte cannot quickly enter the interior of the thick electrode plate.
[0005] In order to achieve the above purpose, this application adopts the following technical solutions:
[0006] The utility model provides a negative electrode plate, which includes:
[0007] The current collector comprises a first surface and a second surface opposite to each other. A first coating layer and a second coating layer are disposed on the first surface and / or the second surface. The height of the first coating layer is different from the height of the second coating layer.
[0008] In some embodiments, there are a plurality of the first coating layer and the second coating layer, and both are in strip shape.
[0009] In some embodiments, the first coating layer and the second coating layer are arranged with the same width.
[0010] In some embodiments, the first coating layer and the second coating layer have the same width.
[0011] In some embodiments, the width of the first coating layer and the second coating layer is 5 mm to 20 mm.
[0012] In some embodiments, the first coating layer and the second coating layer cover an equal area of the current collector.
[0013] In some embodiments, the first surface and the second surface are both provided with the first coating and the second coating, and the first coating and the second coating are symmetrical with respect to the current collector.
[0014] The utility model further proposes to include a diaphragm, a positive electrode sheet and a negative electrode sheet, wherein the diaphragm is arranged between the positive electrode sheet and the negative electrode sheet, and the negative electrode sheet is the negative electrode sheet described in any one of the aforementioned embodiments.
[0015] The utility model further provides a battery, comprising a housing and the battery core described in the above embodiment, wherein the battery core is encapsulated in the housing.
[0016] The technical solution of the utility model arranges coatings of different heights on the current collector so that the electrolyte can quickly enter the interior of the electrode through the shorter coating, thereby improving the energy density of the lithium battery while shortening the transmission path between lithium ions and the electrolyte, effectively improving the problem of easy lithium deposition in thick electrodes. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a structural schematic diagram of an embodiment of a negative electrode plate of the utility model;
[0018] Figure 2 It is a cross-sectional view of another embodiment of a negative electrode sheet of the utility model;
[0019] Figure 3 A top view of another embodiment of a negative electrode sheet of the utility model;
[0020] Figure 4 It is a top view of another embodiment of a negative electrode plate of the utility model. DETAILED DESCRIPTION
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] The utility model provides a negative electrode sheet, referring to Figure 1 As shown, Figure 1 Schematic diagram of the structure of the negative electrode plate, the negative electrode plate includes:
[0026] The current collector 10 includes a first surface and a second surface opposite to each other. A first coating layer 20 and a second coating layer 30 are disposed on the first surface and / or the second surface. The height of the first coating layer 20 and the height of the second coating layer 30 are different.
[0027] As an important component of the negative electrode sheet, the current collector 10 is usually composed of materials with low resistance and good electrical conductivity, such as copper foil, copper mesh, porous carbon materials, etc., which enables the current collector 10 to effectively conduct current, reduce the resistance inside the battery, and improve the overall efficiency of the battery. Preferably, copper foil is used as the material for making the current collector 10 in this embodiment. Copper foil has good thermal conductivity, which helps to quickly dissipate heat when the battery is working and prevent the battery from overheating. In addition, since copper foil can be easily rolled, stretched and formed, it can adapt to battery designs of different shapes and sizes, making copper foil easier to process and use during the battery manufacturing process, and the highly plastic copper foil can ensure that the negative electrode sheet does not have problems such as brittle fracture when winding. At the same time, the lithium embedding capacity of copper foil is relatively small during the battery charging process. Therefore, using copper foil as the main material of the negative electrode sheet of a lithium-ion battery can maintain the stability of the structure and electrochemical properties of the lithium-ion battery.
[0028] In order to store enough electric energy and ensure that lithium ions can flow freely inside the negative electrode sheet, in the embodiment of the present application, a first coating 20 and a second coating 30 are provided on at least one surface of the current collector 10. The first coating 20 and the second coating 30 can be made of the same material or different materials, which can be selected according to actual conditions. The first coating 20 and the second coating 30 are provided on the surface of the current collector 10. Specifically, they can be provided only on one of the first surface or the second surface of the current collector 10, or they can be provided on the first surface and the second surface at the same time. In this case, each surface of the current collector 10 is provided with the first coating 20 and the second coating 30 at the same time.
[0029] Since the height of the first coating 20 is different from that of the second coating 30, there is a height difference between the first coating 20 and the second coating 30, so that there is a larger space for the electrolyte, thereby improving the energy density of the lithium-ion battery; and the shorter coating shortens the path for the electrolyte and lithium ions to diffuse into the interior of the electrode, and the charging speed is faster.
[0030] It can be understood that the shapes of the first coating 20 and the second coating 30 can be selected as needed: illustratively, in a preferred embodiment, the ratio of the first coating 20 and the second coating 30 covering the area of the collector 10 is selected to be 2:1, wherein the first coating 20 is laid on the collector 10 in an irregular shape, followed by rolling, and then the second coating 30 is coated in the gap outside the first coating 20, and rolling is performed again, and it is only necessary to ensure that the height of the first coating 20 is different from the height of the second coating 30.
[0031] like Figure 3 and Figure 4 As shown, in a preferred embodiment, there are a plurality of first coating layers 20 and a plurality of second coating layers 30, and both are in strip shape.
[0032] In this embodiment, since the first coating layer 20 and the second coating layer 30 are both arranged in strips and are regularly coated on the current collector 10, the uniformity of the negative electrode sheet can be improved, the negative electrode sheet can be more stable, and the processing is also convenient. It can be understood that the first coating layer 20 and the second coating layer 30 can be arranged alternately, and there are also various strips, and the coating position and width can be selected as needed, which is explained in conjunction with the following embodiments:
[0033] First embodiment:
[0034] The projection of the first coating 20 and the second coating 30 from a top view is a polygon, and the width of the first coating 20 is 15 mm, and the width of the second coating 30 is 10 mm. The first coating 20 and the second coating 30 are alternately arranged parallel to the diagonal of the current collector 10. The first coating 20 is first applied, followed by rolling, and then the second coating 30 is filled in the gap between the first coatings 20, and rolling is performed again. The negative electrode sheet after forming is as shown in FIG. Figure 3 shown.
[0035] Second embodiment:
[0036] The projection of the first coating 20 and the second coating 30 from a top view is wavy, and the width of the first coating 20 is 10 mm, and the width of the second coating 30 is 15 mm. The first coating 20 and the second coating 30 are alternately arranged parallel to the short side of the current collector 10. The first coating 20 is first applied, followed by rolling, and then the gap between the first coatings 20 is filled with the second coating 30, and rolling is performed again. The negative electrode sheet after forming is as shown in FIG. Figure 4 shown.
[0037] like Figure 1 and Figure 2 As shown, in some embodiments, the first coating layer 20 and the second coating layer 30 are arranged with the same width.
[0038] In this embodiment, the width of the first coating layer 20 and the second coating layer 30 can be set to be equal, so as to facilitate coating on the current collector 10 during production and processing. The specific coating method is as follows: Figure 1 and Figure 2 As shown, at this time, the first coating 20 and the second coating 30 are arranged parallel to the short side of the current collector 10. It can be understood that the first coating 20 and the second coating 30 can also be arranged parallel to the long side of the current collector 10, and the present application does not limit this.
[0039] In a preferred embodiment, the width of the first coating 20 is equal to that of the second coating 30. In this embodiment, a suitable width is selected according to the size of the current collector 10 to ensure that the first coating 20 and the second coating 30 are more evenly distributed on the current collector 10, so that the gap between the two is not too large or too small, which ensures that the electrolyte has sufficient accommodation space and effectively shortens the path for the electrolyte and lithium ions to diffuse into the electrode.
[0040] In the embodiment of the present application, there are multiple options for the width of the first coating 20 and the second coating 30. In a preferred embodiment, the width of the first coating 20 and the second coating 30 can be selected to be 5mm to 20mm. The width of the first coating 20 and the second coating 30 can be selected according to the size of the current collector 10. When the size of the current collector 10 is small, the width of the first coating 20 and the second coating 30 can be selected to be 5mm, and when the size of the current collector 10 is large, the width of the first coating 20 and the second coating 30 can be selected to be 20mm. When the size of the current collector 10 is moderate, the width of the first coating 20 and the second coating 30 can be selected to be 12mm. It can be understood that when the width of the current collector 10 is constant, if the width of the first coating 20 and the second coating 30 is less than 5mm, the processing difficulty is greatly increased. If it is greater than 20mm, the number of the first coating 20 and the second coating 30 is reduced. For the entire pole piece, the ups and downs are too gentle, and the effect of rapid diffusion of lithium ions in the shorter coating cannot be achieved.
[0041] In addition, there are multiple options for the height difference between the first coating 20 and the second coating 30, preferably in the range of 5μm to 25μm. At the same time, if the height difference between the first coating 20 and the second coating 30 is too large or too small, it is not conducive to improving the performance of the negative electrode plate; if the height difference is less than 5μm, there is no obvious difference between the first coating 20 and the second coating 30, and it does not shorten the lithium ion diffusion path; if the height difference is higher than 25 microns, the energy density cannot meet the requirements. Determining the height difference between 5μm and 25μm allows the negative electrode plate to accommodate enough electrolyte and improve the diffusion efficiency of the electrolyte to avoid lithium precipitation.
[0042] In the embodiment of the present application, the first coating 20 and the second coating 30 may also cover the same area of the current collector 10. Since the first coating 20 and the second coating 30 cover the same area, it helps to reduce the unevenness in the negative electrode sheet, reduce the problems that may occur during the cycle, and improve stability.
[0043] like Figure 1 and Figure 2 As shown, in some embodiments, the first coating layer 20 and the second coating layer 30 are disposed on two sides of the current collector 10 and are symmetrical with respect to the current collector 10 .
[0044] Since the first coating 20 and the second coating 30 are coated on both sides of the current collector 10, it means that more energy storage materials participate in the electrochemical reaction, thereby improving the total energy storage capacity of the battery. In addition, by coating the first coating 20 and the second coating 30 on both sides, the utilization rate of the current collector 10 is improved, and the energy density of the battery is improved, which is very important for applications that need to provide more energy in a limited space, such as portable electronic devices and electric vehicles. At the same time, double-sided coating helps to improve the power density of the battery, that is, release more electrical energy in a short time, which plays an important role for applications that require instantaneous high power output, such as the acceleration stage of electric vehicles. At the same time, making the coatings coated on the two sides of the current collector 10 symmetrical relative to the current collector 10 helps to further improve the uniformity of the negative electrode sheet.
[0045] In the embodiment of the present application, there are various material options for the first coating 20 and the second coating 30, such as negative electrode active materials such as graphite. In a preferred embodiment, the first coating 20 and the second coating 30 both include a binder, a conductive agent and a negative electrode active material.
[0046] It should be noted that the materials of the first coating 20 and the second coating 30 are not necessarily the same. For example, if both the first coating 20 and the second coating 30 use graphite as the negative electrode active material, different types of graphite can be selected, including natural graphite, mesophase carbon microsphere artificial graphite, needle coke artificial graphite, petroleum coke artificial graphite, composite graphite, or one or more combinations thereof; and the compaction density of the first coating 20 and the compaction density of the second coating 30 can be adjusted by controlling the compaction density of the selected graphite. Preferably, the compaction density of the first coating 20 is larger, so that a higher energy density can be obtained, and the compaction density of the second coating 30 is smaller, and has a larger porosity, so that the diffusion rate of the electrolyte can be increased.
[0047] The technical solution of the utility model increases the energy density of the lithium battery while retaining the advantage of a shorter lithium ion transmission path by arranging the first coating 20 and the second coating 30 of different heights on the current collector 10, thereby effectively improving the problem of insufficient thick electrode kinetics.
[0048] The utility model further proposes a battery cell, comprising a diaphragm, a positive electrode sheet and a negative electrode sheet, wherein the diaphragm is arranged between the positive electrode sheet and the negative electrode sheet, and the negative electrode sheet is the negative electrode sheet of any one of the aforementioned embodiments.
[0049] Among them, the specific structure of the battery cell electrode piece refers to the above embodiments. Since the 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.
[0050] The utility model also provides a battery, comprising a shell and the battery core described in the above embodiment, wherein the battery core is packaged in the shell.
[0051] The specific structure of the battery cell refers to the above embodiments. Since the battery 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.
[0052] 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 negative electrode plate, characterized in that: include: The current collector comprises a first surface and a second surface opposite to each other. A first coating layer and a second coating layer are disposed on the first surface and / or the second surface. The height of the first coating layer is different from the height of the second coating layer.
2. The negative electrode sheet according to claim 1, characterized in that: There are a plurality of the first coating layer and the second coating layer, and both are in strip shape.
3. The negative electrode sheet according to claim 2, characterized in that: The first coating layer and the second coating layer are arranged with equal width.
4. The negative electrode sheet according to claim 3, characterized in that: The widths of the first coating layer and the second coating layer are equal.
5. The negative electrode sheet according to claim 4, characterized in that: The width of the first coating layer and the second coating layer is 5 mm to 20 mm.
6. The negative electrode sheet according to claim 5, characterized in that: The first coating layer and the second coating layer cover an equal area of the current collector.
7. The negative electrode sheet according to any one of claims 1 to 6, characterized in that: The first surface and the second surface are both provided with the first coating layer and the second coating layer, and the first coating layer and the second coating layer are symmetrical with respect to the current collector.
8. The negative electrode sheet according to claim 7, characterized in that: The first coating layer and the second coating layer both include a binder, a conductive agent and a negative electrode active material.
9. A battery cell, characterized in that: It comprises a diaphragm, a positive electrode sheet and a negative electrode sheet, wherein the diaphragm is arranged between the positive electrode sheet and the negative electrode sheet, and the negative electrode sheet is the negative electrode sheet according to any one of claims 1 to 8.
10. A battery, characterized in that: The invention comprises a housing and the battery core as claimed in claim 9, wherein the battery core is encapsulated in the housing.