Negative pole piece structure, battery and electric device
By coating the graphite negative electrode layer on the surface of the silicon negative electrode layer and defining the thickness relationship, the problem of protruding silicon negative electrode particles piercing the separator is solved, reducing battery self-discharge and improving battery quality and performance.
Patent Information
- Application Number
- CN202420553936.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-21
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2034-03-21
AI Technical Summary
The silicon negative electrode particles are relatively hard, and sharp protrusions are easily formed after laser drilling. The piercing of the separator leads to a micro-short circuit of the positive and negative electrodes, increasing the battery self-discharge and reducing battery performance.
The graphite negative electrode layer is coated on the surface of the silicon negative electrode layer, and the thickness relationship between the silicon negative electrode layer and the graphite negative electrode layer is defined as 10%≤H1/H≤20%, so as to avoid sharp protrusions piercing the diaphragm and reduce the probability of micro-short circuit.
It effectively avoids sharp protrusions piercing the diaphragm, reduces the battery self-discharge problem, and improves the battery quality and performance.
Smart Images
Figure CN222190790U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of battery production and manufacturing, and specifically relates to a negative electrode plate structure, a battery and an electrical device. Background Art
[0002] Nowadays, lithium-ion batteries, as a new type of secondary battery, have the advantages of high energy density and power density, high operating voltage, light weight, small size, long cycle life, good safety, and green environmental protection. They have broad application prospects in portable appliances, power tools, large-scale energy storage, and electric transportation power sources.
[0003] Compared with the traditional carbon negative electrode, the silicon negative electrode has a higher energy density. Currently, some high-energy-density and high-rate lithium battery products basically use silicon negative electrodes, and are used in conjunction with laser drilling technology.
[0004] In the process of realizing the utility model, the inventors found that there are at least the following problems in the prior art: the silicon negative electrode particles are relatively hard, and sharp particle protrusions are easily formed after laser drilling. These protrusions will pierce the diaphragm, thereby causing a micro short circuit between the positive and negative electrodes, resulting in increased battery self-discharge and ultimately causing a decline in battery performance. Utility Model Content
[0005] One of the purposes of the utility model is to provide a negative electrode pole piece structure to address the deficiencies of the prior art. By optimizing the pole piece structure, the problem of increased self-discharge caused by sharp protrusions can be improved, which helps to improve the quality of the battery.
[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:
[0007] A negative electrode plate structure comprises a current collector; a silicon negative electrode layer coated on the surface of the current collector; and a graphite negative electrode layer coated on the surface of the silicon negative electrode layer; wherein the thickness of the silicon negative electrode layer is H, and the thickness of the graphite negative electrode layer is H1, satisfying the relationship: 10%≤H1 / H≤20%.
[0008] Preferably, the current collector has a first surface and a second surface in the thickness direction thereof, and the silicon negative electrode layer covers the first surface and / or the second surface.
[0009] Preferably, the area of the silicon negative electrode layer is equal to the area of the graphite negative electrode layer.
[0010] Preferably, the thickness of the current collector is smaller than the thickness of the graphite negative electrode layer.
[0011] Preferably, the cross-sectional shapes of the current collector, the silicon negative electrode layer and the graphite negative electrode layer are all rectangular.
[0012] Preferably, the current collector is a metal foil or a composite foil.
[0013] Preferably, the current collector has a coating area and a hollow foil area, the current collector located in the hollow foil area is exposed on the surface of the negative electrode plate structure, and the current collector located in the coating area sequentially coats the silicon negative electrode layer and the graphite negative electrode layer.
[0014] Preferably, the empty foil area or the coated area is provided with a tab welding position.
[0015] A second object of the present invention is to provide a battery, comprising the above-mentioned negative electrode plate structure.
[0016] The third object of the present utility model is to provide an electrical device including the above-mentioned battery.
[0017] One of the above technical solutions has the following beneficial effects:
[0018] The utility model optimizes the pole piece structure, coats a graphite negative electrode layer on the surface of the silicon negative electrode layer, and limits the thickness of the silicon negative electrode layer and the thickness of the graphite negative electrode layer to satisfy a preset relationship, thereby preventing sharp protrusions (sharp silicon particles) generated by the silicon negative electrode from piercing the diaphragm, reducing the probability of causing a micro short circuit between the positive and negative electrodes, thereby improving the problem of large self-discharge of the battery and helping to improve the quality of the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The features, advantages and technical effects of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.
[0020] Figure 1 It is a structural schematic diagram of the utility model.
[0021] The reference numerals are described as follows:
[0022] 1-current collector;
[0023] 2- silicon negative electrode layer;
[0024] 3-graphite negative electrode layer;
[0025] 4- Sharp silicon particles. Specific embodiments
[0026] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. For example, "including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.
[0027] Furthermore, the terms “first”, “second”, etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.
[0028] In the utility model, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the utility model can be understood according to the specific circumstances.
[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings, but the present invention is not limited thereto.
[0030] Embodiment 1
[0031] Since silicon negative electrode particles are relatively hard, sharp particle protrusions can easily be formed after laser drilling. These protrusions can pierce the diaphragm, causing micro-short circuits between the positive and negative electrodes, increasing battery self-discharge and ultimately causing battery performance to deteriorate.
[0032] The negative electrode plate structure of the utility model includes a current collector 1; a silicon negative electrode layer 2, coated on the surface of the current collector 1; and a graphite negative electrode layer 3, coated on the surface of the silicon negative electrode layer 2; wherein the thickness of the silicon negative electrode layer 2 is H, and the thickness of the graphite negative electrode layer 3 is H1, satisfying the relationship: 10%≤H1 / H≤20%. The utility model optimizes the plate structure, coats the graphite negative electrode layer 3 on the surface of the silicon negative electrode layer 2, and limits the thickness of the silicon negative electrode layer 2 and the thickness of the graphite negative electrode layer 3 to satisfy the preset relationship, thereby preventing the sharp protrusions (sharp silicon particles 4) generated by the silicon negative electrode from piercing the diaphragm, reducing the probability of causing a micro short circuit between the positive and negative electrodes, thereby improving the problem of large self-discharge of the battery and helping to improve the quality of the battery.
[0033] It should be noted that the silicon negative electrode layer 2 is located above the current collector 1, which can be understood as being located at the bottom layer of the negative electrode plate structure. The graphite negative electrode layer 3 is coated on the surface of the silicon negative electrode layer 2, which can be understood as being located at the surface layer of the negative electrode plate structure. The thickness of the surface graphite negative electrode layer 3 is limited to prevent the graphite negative electrode layer 3 from being too thick and affecting the energy density of the battery.
[0034] In the negative electrode plate structure according to the utility model, the current collector 1 has a first surface and a second surface in the thickness direction, and the silicon negative electrode layer 2 covers the first surface and / or the second surface. In this embodiment, the current collector 1, as the main body of the plate, mainly plays the role of supporting the entire plate, and the two surfaces in the thickness direction are the first surface and the second surface respectively. The silicon negative electrode layer 2 and the graphite negative electrode layer 3 can be coated on the first surface or the second surface, or both of them can be coated on the first surface or the second surface, which is not limited here. In addition, the first surface and the second surface can both be flat surfaces, or can be rough surfaces to improve the strength of bonding with the coating, which is not limited here, and can meet the normal coating material requirements.
[0035] In the negative electrode plate structure according to the utility model, the area of the silicon negative electrode layer 2 is equal to the area of the graphite negative electrode layer 3, so that the graphite negative electrode layer 3 completely covers the silicon negative electrode layer 2, avoiding the sharp protrusions generated by the silicon negative electrode layer 2 from piercing the diaphragm, thereby reducing the probability of causing a micro short circuit between the positive and negative electrodes.
[0036] In the negative electrode sheet structure according to the utility model, the thickness of the current collector 1 is less than the thickness of the graphite negative electrode layer 3, so as to avoid the current collector 1 being too thick and occupying the internal space of the battery, which is not conducive to improving the energy density of the battery.
[0037] The working principle of the utility model is:
[0038] The utility model optimizes the pole piece structure, coats the graphite negative electrode layer 3 on the surface of the silicon negative electrode layer 2, and limits the thickness of the silicon negative electrode layer 2 and the thickness of the graphite negative electrode layer 3 to satisfy a preset relationship, thereby preventing the sharp protrusions (sharp silicon particles 4) generated by the silicon negative electrode from piercing the diaphragm, reducing the probability of causing a micro short circuit between the positive and negative electrodes, thereby improving the problem of large self-discharge of the battery and helping to improve the quality of the battery.
[0039] Embodiment 2
[0040] Different from the first embodiment, the cross-sectional shapes of the current collector 1, the silicon negative electrode layer 2 and the graphite negative electrode layer 3 in this embodiment are all rectangular, and can also be other regular or irregular shapes, which are not limited here. The current collector 1 is a metal foil or a composite foil. The current collector 1 is a structure or part for collecting current. In lithium-ion batteries, it is mainly metal foil, such as copper foil, composite current collector, etc., which mainly collects the current generated by the active substances of the battery to form a larger current for external output. The current collector 1 and the silicon negative electrode layer 2 must ensure full contact and ensure that the internal resistance is small. In addition, foils of other materials can also be used to meet the normal use of the battery, which is not limited here.
[0041] The other structures are the same as those in the first embodiment and will not be described in detail here.
[0042] Embodiment 3
[0043] Different from the first embodiment, the current collector 1 of this embodiment has a coating area and an empty foil area. The current collector 1 located in the empty foil area is exposed on the surface of the negative electrode plate structure. The current collector 1 located in the coating area is coated with a silicon negative electrode layer 2 and a graphite negative electrode layer 3 in sequence. The empty foil area or the coating area is provided with a pole ear welding position. Specifically, the pole plate includes a current collector 1 and a silicon negative electrode layer 2 and a graphite negative electrode layer 3 coated on the surface of the current collector 1. The surface of the pole plate has an empty foil area, and the thickness of the empty foil area is less than the middle normal area. The current collector 1 is exposed to the surface of the empty foil area of the pole plate, and the empty foil area is at both ends or in the middle of the pole plate. The pole ear welding position is set in the empty foil area, which can be understood as the pole ear can be set at the head of the pole plate, but the utility model is not limited to this. The pole ear welding position can also be set in the coating area, which can be understood as the pole ear is set in the middle of the pole plate. In addition, the pole ear can also be set at the head and the middle of the pole plate respectively. The position and number of the pole ear welding positions are not limited here.
[0044] Battery
[0045] The utility model includes the negative electrode plate structures of embodiments one to three.
[0046] The battery comprises a first pole piece, a second pole piece and the above-mentioned separator, wherein the first pole piece, the separator and the second pole piece are sequentially stacked and wound. The first pole piece is a positive pole piece, the second pole piece is a negative pole piece, and the second pole piece adopts the negative pole piece structure of embodiments 1 to 3.
[0047] The two pole pieces are stacked on top of each other and have opposite polarities. The pole pieces with opposite polarities are the positive pole piece and the negative pole piece of the battery. In order to avoid short circuit between the positive and negative pole pieces, a diaphragm is arranged between each two adjacent pole pieces, and the pole pieces with opposite polarities are electrically isolated through the diaphragm.
[0048] In some embodiments, the lithium-ion battery can also be a stacked battery, and the pole pieces with opposite polarities are also electrically isolated by a diaphragm. The polarities of the first pole piece and the second pole piece are opposite, and the first pole piece and the second pole piece can be multiple and stacked on top of each other.
[0049] In some embodiments, the first electrode may be a positive electrode, and the second electrode may be a negative electrode; or the first electrode may be a negative electrode, and the second electrode may be a positive electrode, which is not limited here. The battery may be packaged in an aluminum-plastic film or a steel shell.
[0050] Electrical devices
[0051] The battery containing the negative electrode plate structure of the utility model can also be used in electrical devices, which can be mobile phones, portable devices, notebook computers, etc.
[0052] Comparative Example 1
[0053] The difference from the first embodiment is that the coating layers on both sides of this embodiment are coated with silicon negative electrode to form a negative electrode sheet, and then the separator, positive electrode sheet and negative electrode sheet are stacked and wound in sequence to finally form a battery.
[0054] The batteries of Example 1 and Comparative Example 1 were left standing for 48 hours and then tested for voltage for the first time. The voltage difference between the two tests was divided by the time difference to obtain K value data. The specific test results are shown in Table 1 below.
[0055] Table 1. K value test results of the batteries of Example 1 and Comparative Example 1
[0056] Group K value mean Example 1 0.069mV / h Comparative Example 1 0.21mV / h
[0057] It can be seen from Table 1 that the K value of the battery test prepared in Example 1 is smaller than the K value of Comparative Example 1, indicating that the structure of the utility model can avoid the sharp protrusions of the silicon negative electrode from piercing the diaphragm by coating the graphite negative electrode layer 3 on the surface of the silicon negative electrode layer 2 while ensuring the energy density of the battery, thereby reducing the probability of causing a micro short circuit between the positive and negative electrodes, thereby improving the problem of large self-discharge of the battery.
[0058] It should be noted that in the lithium battery industry or the electrochemical field, the K value represents the voltage drop of the battery per unit time. This indicator is usually used to measure the self-discharge rate of lithium batteries. Generally speaking, the smaller the K value, the better the battery performance.
[0059] According to the disclosure and teaching of the above description, those skilled in the art to which the utility model belongs can also change and modify the above embodiments. Therefore, the utility model is not limited to the above specific embodiments, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the utility model belongs to the protection scope of the utility model. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the utility model.
Claims
1. A negative electrode plate structure, It is characterized in that include: current collector(1); A silicon negative electrode layer (2) coated on the surface of the current collector (1); A graphite negative electrode layer (3) coated on the surface of the silicon negative electrode layer (2); The thickness of the silicon negative electrode layer (2) is H, and the thickness of the graphite negative electrode layer (3) is H1, satisfying the relationship: 10%≤H1 / H≤20%.
2. A negative electrode plate structure as claimed in claim 1, Features: The current collector (1) has a first surface and a second surface in the thickness direction thereof, and the silicon negative electrode layer (2) covers the first surface and / or the second surface.
3. A negative electrode plate structure as claimed in claim 2, Features: The area of the silicon negative electrode layer (2) is equal to the area of the graphite negative electrode layer (3).
4. A negative electrode sheet structure according to any one of claims 1 to 3, Features: The thickness of the current collector (1) is smaller than the thickness of the graphite negative electrode layer (3).
5. A negative electrode sheet structure according to any one of claims 1 to 3, Features: The cross-sectional shapes of the current collector (1), the silicon negative electrode layer (2) and the graphite negative electrode layer (3) are all rectangular.
6. A negative electrode sheet structure according to any one of claims 1 to 3, Features: The current collector (1) is a metal foil or a composite foil.
7. A negative electrode sheet structure according to any one of claims 1 to 3, Features: The current collector (1) comprises a coating area and a hollow foil area, the current collector (1) located in the hollow foil area is exposed on the surface of the negative electrode plate structure, and the current collector (1) located in the coating area sequentially coats the silicon negative electrode layer (2) and the graphite negative electrode layer (3).
8. A negative electrode plate structure as claimed in claim 7, Features: The empty foil area or the coated area is provided with a tab welding position.
9. A battery, Features: The negative electrode sheet structure comprises the negative electrode sheet structure as described in any one of claims 1 to 8.
10. An electrical device, Features: A battery comprising the battery of claim 9.