Negative pole piece, battery monomer, battery and electric equipment
By setting two active material layers with different particle sizes in the negative electrode sheet of the lithium-ion battery, the embedding efficiency of lithium ions is improved, the problem of lithium ion consumption is solved, and the service life of the battery is extended.
Patent Information
- Application Number
- CN202421372872.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-14
- Publication Date
- 2025-05-02
- Estimated Expiration
- 2034-06-14
AI Technical Summary
As the number of charge and discharge of lithium-ion batteries increases, the lithium ions on the negative electrode chip are gradually consumed, resulting in a decrease in battery capacity and shortening service life.
By providing the first negative electrode active material layer and the second negative electrode active material layer in the negative electrode sheet, the average particle size of the material of the second layer is smaller than the first layer, the kinetics and electrolyte capacity of the second layer are increased, and the intercalation of lithium ions and participation in chemical reactions are promoted.
It reduces the precipitation of lithium ions on the surface of the negative electrode sheet, reduces the consumption rate of lithium ions on the negative electrode sheet, and extends the service life of the battery.
Smart Images
Figure CN222826423U_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to the technical field of batteries, and in particular to a negative electrode plate, a battery cell, a battery and an electrical device. Background Art
[0002] Lithium-ion batteries are gaining more and more attention due to their high energy density, high operating voltage, long cycle life and low self-discharge rate, and their application scope is also gradually expanding. Both the positive and negative electrode materials of lithium-ion batteries use lithium-ion intercalation compounds with layered or tunnel structures in which lithium ions can be freely embedded and extracted. When charging, lithium ions are extracted from the positive electrode and embedded in the negative electrode; when discharging, lithium ions are extracted from the negative electrode and embedded in the positive electrode. That is, during the charging and discharging process, lithium ions are embedded and extracted between the positive and negative electrodes in a reciprocating motion.
[0003] However, as the number of charge and discharge cycles of the battery increases, the lithium ions on the negative electrode plate will gradually be consumed, resulting in a decrease in battery capacity. Utility Model Content
[0004] In view of the above problems, the embodiments of the present application provide a negative electrode plate, a battery cell, a battery and an electrical device, which can slow down the consumption rate of lithium ions on the negative electrode plate and extend the service life of the battery.
[0005] According to one aspect of an embodiment of the present application, a negative electrode plate is provided, which includes a negative electrode collector, a first negative electrode active material layer and a second negative electrode active material layer: the first negative electrode active material layer is arranged on at least one side of the negative electrode collector; the second negative electrode active material layer is arranged on a side of the first negative electrode active material layer away from the negative electrode collector, and the average particle size of the material of the second negative electrode active material layer is smaller than the average particle size of the material of the first negative electrode active material layer.
[0006] By adopting the above scheme, since the average particle size of the material of the second negative electrode active material layer is smaller than the average particle size of the material of the first negative electrode active material layer, the gaps between the materials of the second negative electrode active material layer are greater than the gaps between the materials of the first negative electrode active material layer, and thus, the kinetics of the second negative electrode active material layer is higher than that of the first negative electrode active material layer, the second negative electrode active material layer can accommodate more electrolyte, and lithium ions are more easily embedded in the negative electrode plate. That is to say, during the charge and discharge process, more lithium ions will participate in the chemical reaction, reducing the precipitation of lithium ions on the surface of the negative electrode plate, slowing down the consumption rate of lithium ions on the negative electrode plate, and extending the service life of the battery.
[0007] In some embodiments, the negative electrode plate further includes a negative electrode lithium supplement material.
[0008] By adopting the above scheme, the negative electrode lithium supplement material can supplement a certain amount of lithium ions, offset the lithium ion consumption during the battery charging and discharging process, slow down the rate of battery capacity reduction, and extend the battery life.
[0009] In some embodiments, the negative electrode lithium supplement material is located on a side of the second negative electrode active material layer away from the first negative electrode active material layer.
[0010] By adopting the above solution, the negative electrode lithium supplement material is located close to the positive electrode plate, which facilitates the lithium ions released by the negative electrode lithium supplement material to be directly transferred between the positive electrode plate and the negative electrode plate, and participate in the chemical reaction of battery charging and discharging. In addition, the gas generated by the negative electrode lithium supplement material in the process of reacting and releasing lithium ions is more easily discharged from the negative electrode plate, preventing the negative electrode plate from retaining a lot of gas before being packaged into the shell, thereby causing the pressure in the shell of the battery cell to be too high after sealing, thereby having a negative impact on the electrical performance of the battery cell.
[0011] In some embodiments, the negative electrode lithium supplement material is located between the second negative electrode active material layer and the first negative electrode active material layer.
[0012] By adopting the above scheme, the lithium ions released by the negative electrode lithium replenishing material can be embedded in the first negative electrode active material layer and / or the second negative electrode active material layer of the negative electrode plate along with the electrolyte, and further participate in the reciprocating movement of lithium ions between the positive electrode plate and the negative electrode plate during the battery charging and discharging process, thereby achieving the effect of replenishing lithium ions.
[0013] In some embodiments, the negative electrode lithium supplement material is located between the first negative electrode active material layer and the negative electrode current collector.
[0014] By adopting the above scheme, the lithium ions released by the negative electrode lithium replenishing material can be embedded in the first negative electrode active material layer of the negative electrode plate along with the electrolyte, or pass through the first negative electrode active material layer and embed into the second negative electrode active material layer, and further participate in the reciprocating movement of lithium ions between the positive electrode plate and the negative electrode plate during the battery charging and discharging process, thereby achieving the effect of replenishing lithium ions.
[0015] In some embodiments, the negative electrode lithium supplement material is located in the second negative electrode active material layer and / or the first negative electrode active material layer.
[0016] By adopting the above scheme, the negative electrode lithium replenishing material does not need to occupy an additional layer of structure, but is mixed into the first negative electrode active material and / or the second negative electrode active material. The negative electrode lithium replenishing material is directly added to the negative electrode sheet during the molding process of the first negative electrode active material layer and / or the molding process of the second negative electrode active material layer, thereby reducing the processing steps of the negative electrode sheet and improving the processing efficiency of the negative electrode sheet.
[0017] In some embodiments, the thickness of the layer structure formed by the negative electrode lithium supplement material is smaller than the thickness of the first negative electrode active material layer and / or the thickness of the second negative electrode active material layer.
[0018] By adopting the above solution, the cost of adding negative electrode lithium supplement materials can be reduced and lithium plating can be reduced.
[0019] According to a second aspect of the embodiments of the present application, a battery cell is provided, comprising the negative electrode plate in any of the above embodiments.
[0020] According to a third aspect of the embodiments of the present application, a battery is provided, comprising the battery cell in the above embodiments.
[0021] According to a fourth aspect of the embodiments of the present application, there is provided an electrical device, comprising the battery in the above embodiments.
[0022] In the embodiment of the present application, the first negative electrode active material layer and the second negative electrode active material layer are arranged on a single side of the negative electrode current collector, and the average particle size of the material of the second negative electrode active material layer is smaller than the average particle size of the material of the first negative electrode active material layer, so that the gaps between the materials of the second negative electrode active material layer are greater than the gaps between the materials of the first negative electrode active material layer. Therefore, the kinetics of the second negative electrode active material layer is higher than that of the first negative electrode active material layer, the second negative electrode active material layer can accommodate a larger amount of electrolyte, and lithium ions are more easily embedded in the negative electrode plate. During the charge and discharge process, more lithium ions will participate in the chemical reaction, reducing the precipitation of lithium ions on the surface of the negative electrode plate, slowing down the consumption rate of lithium ions on the negative electrode plate, and extending the service life of the battery.
[0023] The above description is only an overview of the technical solution of the embodiment of the present application. In order to more clearly understand the technical means of the embodiment of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0025] Figure 1 This is a schematic diagram of the structure of the first negative electrode plate in the embodiment of the present application.
[0026] Figure 2 Schematic diagram of the structure of a second negative electrode plate in another embodiment of the present application.
[0027] Figure 3 This is a schematic structural diagram of a third negative electrode plate in another embodiment of the present application.
[0028] Figure 4 This is a schematic structural diagram of a fourth negative electrode plate in another embodiment of the present application.
[0029] Figure 5 Schematic diagram of the structure of a fifth negative electrode plate in another embodiment of the present application.
[0030] Figure 6 This is a schematic structural diagram of a sixth negative electrode plate in another embodiment of the present application.
[0031] Explanation of reference numerals: 100, negative electrode current collector; 200, first negative electrode active material layer; 300, second negative electrode active material layer; 400, negative electrode lithium supplement material. DETAILED DESCRIPTION
[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application.
[0034] The terms "comprising" and "having" and any variations thereof in the specification, claims and drawings of this application are intended to cover but not exclude other contents. The word "a" or "an" does not exclude the presence of a plurality.
[0035] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiments" in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.
[0036] The term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.
[0037] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of the negative electrode plates, battery cells, batteries or electrical equipment of the present application. For example, in the description of the present application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present application.
[0038] In addition, the terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order, and may explicitly or implicitly include one or more of the features.
[0039] In the description of the present application, unless otherwise specified, "plurality" means more than two (including two), and similarly, "multiple groups" means more than two groups (including two).
[0040] The present application discloses an electrode assembly, a battery cell, a battery and an electric device, wherein the battery cell includes the electrode assembly, the electric device includes the battery or the battery cell, and can be provided with electric energy by the battery or the battery cell. The electric device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, an energy storage device, an amusement device, an elevator and a lifting device, etc. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. The spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy or an electric airplane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and an electric tool for railways, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator and an electric planer, etc. The energy storage device can be an energy storage wall, a base station energy storage, a container energy storage, etc. The amusement device can be a carousel, a jumping machine, etc. This application does not impose any special restrictions on the above-mentioned electrical equipment.
[0041] For new energy vehicles, the above batteries can be used as a driving power source, thereby replacing fossil fuels to provide driving power.
[0042] The above-mentioned battery can be a battery pack or a battery module. When the above-mentioned battery is a battery pack, the battery pack specifically includes a battery management system (BMS) and a plurality of the above-mentioned battery cells. The plurality of battery cells can be electrically connected in series, in parallel, or in a mixture of series and parallel, and communicated with the battery management system to form a battery pack, and the above-mentioned battery management system controls and monitors the working status of each battery cell. In addition, the plurality of battery cells can also be first connected in series and / or in parallel, and form a battery module with the module management system, and then the plurality of battery modules are electrically connected in series, in parallel, or in a mixture of series and parallel, and together with the battery management system form a battery pack.
[0043] The battery pack or battery module may be mounted on a supporting structure such as a box, frame, or bracket, and the battery cells and the battery management system may be electrically connected to each other through a busbar, such as a bar. The battery cells may be lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, and their outer contours may be cylindrical, flat, rectangular, or other shapes, but are not limited thereto.
[0044] Generally, a battery cell includes a battery housing and an electrode assembly, and the electrode assembly is contained in the battery housing. The electrode assembly is the smallest unit for electrochemical reaction in the battery, which realizes the charge and discharge of the battery cell, and usually includes a positive electrode sheet, a negative electrode sheet, and a diaphragm separating the positive electrode sheet and the negative electrode sheet. The battery housing is injected with electrolyte, which can infiltrate the interior of the electrode assembly, providing an ion migration path for the electrochemical reaction of the electrode assembly and playing a conductive role.
[0045] During the use of existing batteries, as the number of charge and discharge times of the battery increases, the lithium ions on the negative electrode plate will gradually be consumed, resulting in a decrease in battery capacity.
[0046] The inventors have discovered through research that lithium ions are consumed mainly in two processes.
[0047] One is based on the consumption of the solid electrolyte interface film (SEI). During the first charge and discharge process of lithium ions, the electrode material will react with the electrolyte at the solid-liquid interface to form a passivation layer covering the surface of the electrode material. This passivation layer is called the solid electrolyte interface film (SEI), which can effectively prevent the passage of solvent molecules, but lithium ions can pass freely. The SEI film will consume some lithium ions, resulting in a decrease in the capacity of the battery. Moreover, whether it is traditional graphite materials or new high-capacity alloy composite materials, the SEI film will be continuously destroyed and repaired during the battery cycle and storage process, causing the active lithium to be continuously consumed.
[0048] Second, due to insufficient infiltration of the electrolyte into the negative electrode plate, it is difficult for lithium ions to be embedded in the negative electrode active material during the charging process. A large number of lithium ions accumulate on the surface of the negative electrode plate, causing lithium precipitation, thereby consuming some lithium ions.
[0049] The loss of lithium ions in the above processes is irreversible.
[0050] In the related art, the loss of lithium ions is generally compensated by adding lithium supplement materials, so as to improve the capacity and cycle performance of the battery after multiple charge and discharge cycles.
[0051] However, simply adding lithium-supplementing materials to make up for the loss of lithium ions still does not reduce the efficiency of lithium ion loss from the source. The continuous accumulation of lithium ion precipitation will also cause a series of negative problems and affect the performance of the battery.
[0052] In view of the above problems, the embodiments of the present application provide a negative electrode plate, a battery cell, a battery and an electrical device.
[0053] like Figure 1As shown, the negative electrode sheet includes a negative electrode collector 100, a first negative electrode active material layer 200 and a second negative electrode active material layer 300: the first negative electrode active material layer 200 is arranged on at least one side of the negative electrode collector 100; the second negative electrode active material layer 300 is arranged on the side of the first negative electrode active material layer 200 away from the negative electrode collector 100, and the average particle size of the material of the second negative electrode active material layer 300 is smaller than the average particle size of the material of the first negative electrode active material layer 200.
[0054] For example, the average particle size of the material of the first negative electrode active material layer 200 is 600 meshes, and the average particle size of the material of the second negative electrode active material layer 300 is 400 meshes.
[0055] Alternatively, the maximum particle size of the material of the first negative electrode active material layer 200 and the maximum particle size of the material of the second negative electrode active material layer 300 can be controlled to achieve the purpose of controlling the average particle size of the material of the second negative electrode active material layer 300 to be smaller than the average particle size of the material of the first negative electrode active material layer 200. The embodiment of the present application does not specify a method for controlling and measuring the average particle size of the material of the first negative electrode active material layer 200 and the average particle size of the material of the second active material layer.
[0056] The materials of the first negative electrode active material layer 200 and the second negative electrode active material layer 300 may include but are not limited to one or more of graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microbeads, silicon-based materials, tin-based materials, lithium titanate or other metals that can form alloys with lithium.
[0057] In addition, the material of the first negative electrode active material layer 200 and the material of the second negative electrode active material layer 300 may be the same as or different from each other.
[0058] The negative electrode current collector 100 is generally a structure or part for collecting current. The negative electrode current collector 100 may be any material suitable for use as a negative electrode current collector 100 for a lithium-ion battery in the art. For example, the negative electrode current collector 100 may include but is not limited to metal foil, and more specifically may include but is not limited to copper foil or carbon-coated copper foil.
[0059] Since the average particle size of the material of the second negative electrode active material layer 300 is smaller than the average particle size of the material of the first negative electrode active material layer 200, the gaps between the materials of the second negative electrode active material layer 300 are greater than the gaps between the materials of the first negative electrode active material layer 200. Therefore, the kinetics of the second negative electrode active material layer 300 is higher than that of the first negative electrode active material layer 200, the second negative electrode active material layer 300 can accommodate more electrolyte, and lithium ions are more easily embedded in the negative electrode sheet.
[0060] That is to say, during the charge and discharge process, the lithium ions are embedded at a greater rate and depth in the second negative electrode active material layer 300, and are more easily able to reach the first negative electrode active material layer 200, thereby reducing the precipitation of lithium ions on the surface of the negative electrode plate, slowing down the lithium ion consumption rate on the negative electrode plate, and extending the service life of the battery.
[0061] like Figures 2 to 6 As shown, in some embodiments, the negative electrode plate further includes a negative electrode lithium supplement material 400 .
[0062] On the basis of slowing down the lithium ion consumption rate, the negative electrode lithium supplement material 400 can supplement a certain amount of lithium ions to offset the lithium ion consumption during the battery charge and discharge process, slow down the rate at which the battery capacity decreases, and extend the battery life.
[0063] The negative electrode lithium supplement material 400 may include one or more of lithium foil, lithium silicide powder and stabilized lithium metal powder, which is not limited in the embodiment of the present application.
[0064] Please refer to Figure 2 and Figure 3 The negative electrode lithium supplement material 400 may be dispersed in the first negative electrode active material layer 200 and / or the second negative electrode active material layer 300 in the negative electrode sheet. Figures 4 to 6 The negative electrode lithium replenishing material 400 may also be a separate negative electrode lithium replenishing layer.
[0065] Figure 2 It shows that the negative electrode lithium supplement material 400 is dispersed in the first negative electrode active material layer 200. Figure 3 It is shown that the negative electrode lithium supplement material 400 is dispersed in the second negative electrode active material layer 300 . Figure 4 It is shown that the negative electrode lithium supplement material 400 is located on the side of the second negative electrode active material layer 300 away from the first negative electrode active material layer 200 . Figure 5 It is shown that the negative electrode lithium supplement material 400 is located between the second negative electrode active material layer 300 and the first negative electrode active material layer 200 . Figure 6 It is shown that the negative electrode lithium supplement material 400 is located between the first negative electrode active material layer 200 and the negative electrode current collector 100 .
[0066] It is understandable that the negative electrode lithium supplement material 400 may be dispersed in both the first negative electrode active material layer 200 and the second negative electrode active material layer 300 , which is not shown in the drawings of the present application.
[0067] It should be noted that when the negative electrode lithium replenishing material 400 is dispersed in the first negative electrode active material layer 200 and / or the second negative electrode active material layer 300, the negative electrode lithium replenishing material 400 can only be in powder or granular form, for example, the negative electrode lithium replenishing material 400 is lithium silicide powder and / or stabilized lithium metal powder.
[0068] During the manufacturing process of the negative electrode plate, the negative electrode lithium replenishing material 400 is added to the first negative electrode active material layer 200 and / or the second negative electrode active material layer 300 and stirred evenly, and then the first negative electrode active material layer 200 and / or the second negative electrode active material layer 300 are sprayed onto the negative electrode current collector 100 without adding an additional spraying step of the negative electrode lithium replenishing material 400, thereby reducing the processing steps of the negative electrode plate and improving the processing efficiency of the negative electrode plate.
[0069] When the negative electrode lithium replenishing material 400 exists in the negative electrode plate as a separate negative electrode lithium replenishing layer, the negative electrode lithium replenishing material 400 exists in the following three positions:
[0070] like Figure 4 As shown, the first type is: the negative electrode lithium supplement material 400 is located on a side of the second negative electrode active material layer 300 away from the first negative electrode active material layer 200 .
[0071] When the negative electrode plate is assembled to the electrode assembly, the negative electrode lithium supplement material 400 is located close to the positive electrode plate, which facilitates the lithium ions released by the negative electrode lithium supplement material 400 to be directly transferred between the positive electrode plate and the negative electrode plate, and participate in the chemical reaction of battery charging and discharging. In addition, the gas generated by the negative electrode lithium supplement material 400 in the process of reacting and releasing lithium ions is more easily discharged outside the negative electrode plate, preventing the negative electrode plate from retaining a lot of gas before being packaged into the shell, thereby causing the pressure in the shell of the battery cell to be too high after sealing, thereby having a negative impact on the electrical performance of the battery cell.
[0072] like Figure 5 As shown, the second type is: the negative electrode lithium supplement material 400 is located between the second negative electrode active material layer 300 and the first negative electrode active material layer 200 .
[0073] By adopting the above scheme, the lithium ions released by the negative electrode lithium replenishing material 400 can be embedded in the first negative electrode active material layer 200 and / or the second negative electrode active material layer 300 of the negative electrode plate along with the electrolyte, and further participate in the reciprocating movement of lithium ions between the positive electrode plate and the negative electrode plate during the battery charging and discharging process, thereby achieving the effect of replenishing lithium ions.
[0074] like Figure 6 As shown, the third type is: the negative electrode lithium supplement material 400 is located between the first negative electrode active material layer 200 and the negative electrode current collector 100 .
[0075] By adopting the above scheme, the lithium ions released by the negative electrode lithium replenishing material 400 can be embedded in the first negative electrode active material layer 200 of the negative electrode plate along with the electrolyte, or pass through the first negative electrode active material layer 200 and be embedded in the second negative electrode active material layer 300, and further participate in the reciprocating movement of lithium ions between the positive electrode plate and the negative electrode plate during the battery charging and discharging process, thereby achieving the effect of replenishing lithium ions.
[0076] It is understandable that when the negative electrode lithium replenishing material 400 exists in the negative electrode plate as a separate negative electrode lithium replenishing layer, the negative electrode lithium replenishing material 400 may include any one or more of lithium foil, lithium silicide powder and stabilized lithium metal powder.
[0077] For example, the negative electrode lithium supplement material 400 is lithium foil, which covers the side of the second negative electrode active material layer 300 away from the first negative electrode active material layer 200, and is rolled to make the lithium foil and the second negative electrode active material layer 300 adhere better.
[0078] In another example, the negative electrode lithium replenishing material 400 is lithium silicide powder or stabilized lithium metal powder, which is evenly sprayed on the side of the second negative electrode active material layer 300 away from the first negative electrode active material layer 200, and through a rolling process, the lithium silicide powder or stabilized lithium metal powder is attached to the surface of the second negative electrode active material layer 300 to form a dense negative electrode lithium replenishing layer.
[0079] Please refer to Figures 4 to 6 When the negative electrode lithium replenishing material 400 exists in the negative electrode sheet as a separate layer structure, the thickness of the layer structure formed by the negative electrode lithium replenishing material 400 is less than the thickness of the first negative electrode active material layer 200 and / or the thickness of the second negative electrode active material layer 300.
[0080] When the thickness of the layer structure formed by the negative electrode lithium supplement material 400 is too large, the lithium concentration per unit area is too high, and the negative electrode needs more points to store lithium elements, thereby limiting the energy density of the battery. When lithium ions cannot find a location to embed, lithium precipitation may be aggravated.
[0081] By controlling the thickness of the layer structure formed by the negative electrode lithium supplement material 400 , the energy density of the battery can be improved, the occurrence of lithium plating can be reduced, and the cost of adding the negative electrode lithium supplement material 400 can be reduced.
[0082] In summary, the embodiment of the present application arranges the first negative electrode active material layer 200 and the second negative electrode active material layer 300 on one side of the negative electrode current collector 100, and the average particle size of the material of the second negative electrode active material layer 300 is smaller than the average particle size of the material of the first negative electrode active material layer 200, so that the gaps between the materials of the second negative electrode active material layer 300 are greater than the gaps between the materials of the first negative electrode active material layer 200. Therefore, the kinetics of the second negative electrode active material layer 300 is higher than that of the first negative electrode active material layer 200, the second negative electrode active material layer 300 can accommodate more electrolyte, and lithium ions are more easily embedded in the negative electrode plate. During the charge and discharge process, more lithium ions will participate in the chemical reaction, reducing the precipitation of lithium ions on the surface of the negative electrode plate, slowing down the consumption rate of lithium ions on the negative electrode plate, and extending the service life of the battery.
[0083] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.
[0084] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. A negative electrode plate, characterized in that: include: Anode current collector; A first negative electrode active material layer is provided on at least one side of the negative electrode current collector; The second negative electrode active material layer is disposed on a side of the first negative electrode active material layer away from the negative electrode current collector, and the average particle size of the material of the second negative electrode active material layer is smaller than the average particle size of the material of the first negative electrode active material layer.
2. The negative electrode sheet according to claim 1, characterized in that: It also includes negative electrode lithium replenishing materials.
3. The negative electrode sheet according to claim 2, characterized in that: The negative electrode lithium supplement material is located on a side of the second negative electrode active material layer away from the first negative electrode active material layer.
4. The negative electrode sheet according to claim 2, characterized in that: The negative electrode lithium supplement material is located between the second negative electrode active material layer and the first negative electrode active material layer.
5. The negative electrode sheet according to claim 2, characterized in that: The negative electrode lithium supplement material is located between the first negative electrode active material layer and the negative electrode current collector.
6. The negative electrode sheet according to claim 2, characterized in that: The negative electrode lithium supplement material is located in the second negative electrode active material layer and / or the first negative electrode active material layer.
7. The negative electrode sheet according to any one of claims 3 to 5, characterized in that: The thickness of the layer structure formed by the negative electrode lithium supplement material is smaller than the thickness of the first negative electrode active material layer and / or the thickness of the second negative electrode active material layer.
8. A battery cell, characterized in that: The invention comprises the negative electrode sheet as described in any one of claims 1 to 7.
9. A battery, characterized in that: Comprising the battery cell according to claim 8.
10. An electrical device, characterized in that: A battery comprising the battery of claim 9.