Electrode and lithium ion battery

Abstract

The invention provides an electrode and a lithium ion battery. The electrode comprises a current collector, a first electrode layer and a second electrode layer which are stacked, wherein the material of the first electrode layer comprises a first active material with Dv50 being X, the material of the second electrode layer comprises a second active material, X is 4 [mu] m-8 [mu] m, Y is 10 [mu] m-20 [mu] m, and 1 / 3 < = X / Y < 1. When large particles are accumulated in the second electrode layer, macroscopic pores with large sizes can be formed among the particles, the capillary resistance of the pores is extremely low, the electrolyte can rapidly permeate and rapidly penetrate through the whole second electrode layer through gravity or slight negative pressure to become a main channel for the electrolyte to diffuse to a deep layer, and the situation that permeation is hindered due to too small pores is avoided; it is ensured that the electrolyte rapidly reaches the two-layer interface, after the electrolyte reaches the first electrode layer containing the first active material with the small particle size, 'global infiltration 'can be achieved by means of mesoscopic pores among small particles, and the wettability of the electrolyte is effectively improved.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to an electrode and a lithium-ion battery. Background Technology

[0002] Lithium-ion batteries (LIBs), as an important energy storage technology, have been widely used in electronic devices and are increasingly expanding into electric vehicles (EVs) and grid energy storage. With the growing demand for higher energy density LIBs and improved performance, a major technical challenge in developing high-energy-density lithium-ion batteries is improving electrode capacity utilization. Improving electrolyte wettability is considered key to solving this problem. Furthermore, uneven wetting can lead to uneven current density distribution, which in turn destabilizes the formation of the solid electrolyte interphase (SEI) film.

[0003] Traditional anode materials are mainly natural or artificial graphite, which have a strongly hydrophobic surface (low surface energy). Electrolytes, on the other hand, are primarily polar carbonate solvents (such as EC and DMC). The poor interfacial affinity between the hydrophobic surface and the polar electrolyte makes it difficult for the electrolyte to spread on the graphite surface. Furthermore, the electrodes often use graphite particles of a relatively uniform size, which tend to form a uniform but dense layer structure when stacked. Due to capillary resistance, the electrolyte has difficulty penetrating, ultimately leading to insufficient surface wetting but incomplete internal wetting. This directly affects the overall performance of the battery and may even cause safety hazards such as lithium plating on the anode. Summary of the Invention

[0004] Therefore, it is necessary to provide an electrode and a lithium-ion battery with good wettability.

[0005] This application provides an electrode, comprising a current collector, a first electrode layer, and a second electrode layer stacked sequentially;

[0006] The material of the first electrode layer includes D v50 The first active material is X, and the material of the second electrode layer includes D. v50 X is the second active material of Y, where X is 4μm~8μm and Y is 10μm~20μm and 1 / 3≤X / Y<1.

[0007] In one embodiment, the areal density ratio of the first electrode layer to the second electrode layer is (1~9): (1~9).

[0008] In one embodiment, the first electrode layer satisfies one or more of the following conditions:

[0009] (1) D of the first active material v50 The thickness is 5μm to 6μm;

[0010] (2) The specific surface area of ​​the first active material is 1.5 m². 2 / g~2.5m 2 / g;

[0011] (3) The material composition of the first electrode layer includes, by mass percentage, 95.5% to 97.5% of the first active material, 0.3% to 0.5% of the first conductive agent, and 1.8% to 4% of the first auxiliary agent;

[0012] (4) The compaction density of the first electrode layer is 1.45 g / cc to 1.55 g / cc.

[0013] In one embodiment, one or both of the following conditions are met:

[0014] (1) The first additive includes a first dispersant and a first binder. The material composition of the first electrode layer includes, by mass percentage, 95.5% to 97.5% of the first active material, 0.3% to 0.5% of the first conductive agent, 0.5% to 0.7% of the first dispersant and 1.3% to 3.7% of the first binder;

[0015] (2) The first active material includes one or more of carbon materials and silicon materials.

[0016] In one embodiment, the second electrode layer satisfies one or more of the following conditions:

[0017] (1) D of the second active material v50 The thickness is 12μm~15μm;

[0018] (2) The specific surface area of ​​the second active material is 1m². 2 / g~2 m 2 / g;

[0019] (3) The material composition of the second electrode layer includes, by mass percentage, 95.5% to 97.5% of the second active material, 0.3% to 0.5% of the second conductive agent, and 1.8% to 5% of the second auxiliary agent;

[0020] (4) The compaction density of the second electrode layer is 1.58 g / cc to 1.65 g / cc.

[0021] In one embodiment, the second active material includes a central active material and a coating layer covering the central active material, wherein the material of the coating layer is 1% to 5% of the mass of the central active material.

[0022] In one embodiment, one or more of the following conditions are met:

[0023] (1) The material of the coating layer includes one or more of asphalt, resin materials and hard carbon materials;

[0024] (2) The second additive includes a second dispersant and a second binder. The material composition of the second electrode layer includes, by mass percentage, 95.5% to 97.5% of the second active material, 0.3% to 0.5% of the second conductive agent, 0.5% to 0.7% of the second dispersant and 1.3% to 3.7% of the second binder;

[0025] (3) The central active material includes one or both of carbon materials and silicon materials.

[0026] In one embodiment, the current collector includes copper foil, aluminum foil, nickel foil, or a polymer-metal composite current collector.

[0027] In one embodiment, the thickness of the current collector is 4.5 μm to 8 μm.

[0028] This application also provides a lithium-ion battery, including a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the separator is disposed between the positive electrode and the negative electrode, and the positive electrode, the negative electrode, and the separator are immersed in the electrolyte, and the negative electrode includes the electrode as described above.

[0029] This application provides a first electrode layer comprising a first active material with a small particle size and a second active material with a large particle size, sequentially stacked on a current collector. The second electrode layer contains a large particle accumulation, forming large macroscopic pores between the particles. These pores have extremely low capillary resistance, allowing the electrolyte to rapidly permeate through the entire second electrode layer via gravity or slight negative pressure, becoming the "main channel" for electrolyte diffusion to deeper layers. This avoids obstruction of permeation due to excessively small pores, ensuring the electrolyte quickly reaches the interface between the two layers. Once the electrolyte reaches the first electrode layer containing the small-particle-size first active material, "full-area wetting" can be achieved through the mesoscopic pores between the small particles, effectively improving the wettability of the electrolyte. This significantly reduces electrode impedance and polarization, and enhances the charging speed and cycle performance of the battery containing the aforementioned electrode. Detailed Implementation

[0030] To facilitate understanding of this application, it may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0032] As used herein, the term "and / or" encompasses any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" includes three parallel options: A, B, and "a combination of A and B".

[0033] In this document, unless otherwise stated, "one or more" means any one of the listed items or any combination of the listed items. Similarly, "one or more" and other instances of "one or more" are to be understood in the same way unless otherwise stated.

[0034] In this document, terms such as "further," "even further," "especially," "for example," "like," "example," and "exemplary" are used for descriptive purposes to indicate a connection in the coverage of different technical solutions presented earlier and later. However, they should not be construed as limitations on the preceding technical solution or on the scope of protection of this document. Unless otherwise specified, in this document, A (e.g., B) indicates that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0035] In this document, "optionally," "optionally," and "optional" mean that something is optional, that is, it is selected from either "present" or "absent." If multiple "options" appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "option" is independent. In this application, descriptions such as "optionally contains" and "optionally includes" indicate "contains or does not contain." "Optional component X" indicates whether component X exists or does not exist, or whether component X is contained or not.

[0036] In this document, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood as not constituting a closed limitation on quantity.

[0037] In this article, the technical features described in an open-ended manner include both closed technical solutions composed of the listed features and open technical solutions that include the listed features.

[0038] In this document, when referring to numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of selectable values ​​within a numerical interval is considered continuous, and includes the two endpoints (i.e., the minimum and maximum values) of the numerical interval, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, and other numerical interval types.

[0039] In this document, the terms "room temperature" or "normal temperature" generally refer to 4°C to 35°C, for example, 20°C ± 5°C. In some embodiments of this document, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of this document, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0040] In this document, for methods involving multiple steps, unless otherwise explicitly stated herein, there is no strict order constraint on the execution of these steps; they may be executed in any order other than those described. Moreover, any step may include multiple sub-steps or multiple stages, which are not necessarily completed at the same time, but may be executed at different times, and their execution order is not necessarily sequential, but may be executed in turn, alternately, or simultaneously with other steps or parts of the sub-steps or stages of other steps.

[0041] This application provides an electrode, comprising a current collector, a first electrode layer, and a second electrode layer stacked sequentially;

[0042] The material of the first electrode layer includes D v50 The first active material is X, and the material of the second electrode layer includes D. v50 X is the second active material of Y, where X is 4μm~8μm and Y is 10μm~20μm and 1 / 3≤X / Y<1.

[0043] Understandably, D v50It is the volume median particle size, which means that in the particle group being tested, 50% of the volume of particles have a particle size smaller than this value, while 50% of the volume of particles have a particle size larger than this value.

[0044] This application provides a first electrode layer comprising a first active material with a small particle size and a second active material with a large particle size, sequentially stacked on a current collector. When there is a large particle accumulation in the second electrode layer, large macroscopic pores are formed between the particles. These pores have extremely low capillary resistance, allowing the electrolyte to quickly permeate through the entire second electrode layer by gravity or slight negative pressure, becoming the "main channel" for the electrolyte to diffuse into deeper layers. This avoids the pores being too small to hinder permeation, ensuring that the electrolyte quickly reaches the interface between the two layers. After the electrolyte reaches the first electrode layer containing the first active material with a small particle size, "full-area wetting" can be achieved by utilizing the mesoscopic pores between the small particles, effectively improving the wettability of the electrolyte. This can significantly reduce the impedance and polarization of the electrode, and improve the charging speed and cycle performance of the battery containing the above-mentioned electrode.

[0045] Furthermore, the ratio between X and Y can be, but is not limited to, 0.34, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 0.99.

[0046] In a specific example, the areal density ratio of the first electrode layer to the second electrode layer is (1~9):(1~9). Specifically, the areal densities of the first electrode layer and the second electrode layer can be, but are not limited to, 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, or 1:9. It can be understood that the total areal density of the first electrode layer and the second electrode layer is constant.

[0047] Understandably, the first active material includes one or more of carbon materials and silicon materials. Specifically, the aforementioned carbon materials include, but are not limited to, one or more of graphite, porous carbon, hard carbon, soft carbon, and mesophase carbon microspheres.

[0048] In a specific example, the D of the first active material v50 The diameter is 5μm~6μm; specifically, the D of the first active material v50 It can be, but is not limited to, 5μm, 5.1μm, 5.2μm, 5.3μm, 5.4μm, 5.5μm, 5.6μm, 5.7μm, 5.8μm, 5.9μm or 6μm.

[0049] In one specific example, the specific surface area of ​​the first active material is 1.5 m². 2 / g~2.5m 2 / g; Specifically, the specific surface area of ​​the first active material may be, but is not limited to, 1.5m². 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 m 2 / g, 1.9 m 2 / g、2 m 2 / g、2.1 m 2 / g、2.2 m 2 / g、2.3 m 2 / g、2.4 m 2 / g or 2.5 m 2 / g.

[0050] In one specific example, the material composition of the first electrode layer, by mass percentage, includes 95.5% to 97.5% of a first active material, 0.3% to 0.5% of a first conductive agent, and 1.8% to 5% of a first additive. Further, the material composition of the first electrode layer, by mass percentage, includes 95.5% to 97.5% of a first active material, 0.3% to 0.5% of a first conductive agent, 0.5% to 0.7% of a first dispersant, and 1.3% to 3.7% of a first binder.

[0051] In a specific example, the D of the second active material v50 The diameter is 12μm~15μm; specifically, the D of the second active material v50 It can be, but is not limited to, 12μm, 12.5μm, 13μm, 13.5μm, 14μm, 14.5μm or 15μm.

[0052] In a specific example, the specific surface area of ​​the second active material is 1 m². 2 / g~2 m 2 / g; Specifically, the specific surface area of ​​the second active material can be, but is not limited to, 1m². 2 / g、1.1 m 2 / g, 1.2 m 2 / g, 1.3 m 2 / g, 1.4 m 2 / g, 1.5 m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 m 2 / g, 1.9 m 2 / g or 2 m 2 / g.

[0053] In one specific example, the material composition of the second electrode layer includes, by mass percentage, 95.5% to 97.5% of a second active material, 0.3% to 0.5% of a second conductive agent, and 1.8% to 4% of a second additive; further, the material composition of the second electrode layer includes, by mass percentage, 95.5% to 97.5% of a second active material, 0.3% to 0.5% of a second conductive agent, 0.5% to 0.7% of a second dispersant, and 1.3% to 3.7% of a second binder.

[0054] In a specific example, the second active material includes a central active material and a coating layer covering the active material. The material of the coating layer is 1% to 5% of the mass of the central active material. Specifically, the material of the coating layer may be, but is not limited to, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5% of the mass of the central active material. Further, the material of the coating layer includes one or two of bitumen, resin materials, and hard carbon materials. Specifically, the resin material may be, but is not limited to, one or more of phenolic resin, epoxy resin, and polyfurfuryl alcohol (PFA-C).

[0055] In a specific example, the central active material includes one or more of carbon and silicon. It is understood that the central active material is a primary particle. Specifically, the aforementioned carbon material includes, but is not limited to, one or more of graphite, porous carbon, hard carbon, soft carbon, and mesophase carbon microspheres.

[0056] Furthermore, the first binder and the second binder are each independently selected from one or both of styrene-butadiene rubber and acrylic acid. The first dispersant and the second dispersant include carboxymethyl cellulose. The first conductive agent and the second conductive agent each independently include one or more of graphene, carbon black, carbon nanotubes, and polyaniline.

[0057] In a specific example, the current collector includes copper foil, aluminum foil, nickel foil, or a polymer-metal composite current collector.

[0058] Compared to traditional current collectors, polymer-metal composite current collectors reduce cost and weight by replacing some of the metal material with polymer materials. This involves a "sandwich" structure where the middle layer uses polymers like PET / PP, and the top and bottom layers are thinned metal layers. Compared to traditional current collectors, the use of a polymer middle layer not only increases battery energy density and reduces cost by reducing the weight of the composite current collector, but also improves battery safety. The reduced metal thickness means that burrs formed when the surface metal is punctured are less likely to puncture the battery separator, lowering the risk of short circuits.

[0059] In a specific example, the thickness of the current collector is 4.5 μm to 8 μm. Specifically, the thickness of the current collector can be, but is not limited to, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm or 8 μm.

[0060] This application also provides a method for preparing the above-mentioned electrode, including the following steps:

[0061] The material of the first electrode layer is coated onto the current collector to prepare the first electrode layer;

[0062] The second electrode layer is prepared by coating the material of the second electrode layer onto the second electrode layer.

[0063] Furthermore, the preparation method of the material of the first electrode layer includes dry mixing the first active material and the first conductive agent, and then adding the first auxiliary agent to make the viscosity reach 2000 Pa·s~6000 mPa·s.

[0064] Furthermore, the preparation method of the second electrode layer material includes dry mixing the second active material and the second conductive agent, and then adding the second auxiliary agent to make the viscosity reach 2000 Pa·s~6000 mPa·s.

[0065] This application also provides a lithium-ion battery, including a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is disposed between the positive electrode and the negative electrode. The positive electrode, the negative electrode, and the separator are immersed in the electrolyte. The negative electrode includes the electrode as described above.

[0066] The present application will be further described in detail below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0067] In the specific embodiments described below, the measurement parameters of the raw material components may have slight deviations within the weighing accuracy range unless otherwise specified. Temperature and time parameters are subject to acceptable deviations due to instrument testing accuracy or operational precision. "Ambient temperature" refers to 25°C; "atmospheric pressure" refers to 100 kPa or 101 kPa.

[0068] Example 1

[0069] This embodiment provides an electrode, the preparation method of which includes the following steps:

[0070] 5μm copper foil is provided.

[0071] The material of the first electrode layer, by mass percentage, comprises 97% graphite, 0.4% conductive carbon black, 0.6% CMC dispersant, 0.6% PAA binder, and 1.4% SBR binder, and the first active material is graphite D. V50 It has a diameter of 6 μm and a specific surface area of ​​2.1 m². 2 / g, the above graphite and conductive carbon black are dry-mixed, then CMC adhesive, PAA binder and SBR binder are added and stirred evenly until the viscosity reaches 2000-6000 mPa·s, and the designed single-sided areal density is 59.5 g / m². 2 The compaction density of the roller is 1.55 g / cc.

[0072] The material for the second electrode layer, by mass percentage, comprises 97% pitch-coated graphite, 0.4% conductive carbon black, 0.6% CMC dispersant, 0.6% PAA binder, and 1.4% SBR binder. The surface of the second active material has pitch-coated graphite with a coating amount of 1.5% (the mass ratio of pitch to graphite is 1.5:100). V50 Its diameter is 12.2 μm, and its specific surface area is 1.50 m². 2 / g, the above graphite and conductive carbon black are dry-mixed, then CMC adhesive, PAA binder and SBR binder are added and stirred evenly until the viscosity reaches 2000-6000 mPa·s. This mixture is then coated onto the first electrode layer, with a designed single-sided areal density of 25.5 g / m². 2 The compaction density is 1.62 g / cc.

[0073] Other embodiments and comparative examples differing from Embodiment 1 are summarized in Table 1 below. The total areal density of the first and second electrode layers is 85 g / cm³. 2 .

[0074] Table 1

[0075]

[0076] Performance testing and results analysis

[0077] The electrodes from the above embodiments and comparative examples were used as negative electrodes for lithium-ion batteries. The positive electrode of the lithium-ion battery consisted of a 15 μm thick aluminum foil, double-sided coated, with consistent density and thickness of the positive active material layer on both sides of the aluminum foil. The total thickness of the positive active material layer was 177.2 μm, and the positive active material layer contained NCM811, CNT, SP, and PVDF in a mass ratio of 97:0.5:0.5:2.0. The separator was a 12 μm thick polyethylene separator, and the electrolyte was a 1 mol / L LiPF6 solution with a volume ratio of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). Performance tests were conducted on the batteries including the negative electrode sheets from the above embodiments and comparative examples.

[0078] The prepared lithium-ion batteries were tested for capacity, rate capability, and cycle performance. The test results are shown in Table 2.

[0079] Table 2

[0080]

[0081] As can be seen from Comparative Examples 1 and 2 above, the active materials of the first electrode layer and the second electrode layer are not within the corresponding particle size range, resulting in a significant decrease in battery performance. Furthermore, in the above embodiments, the second active material particles in Example 5 are larger, leading to a longer Li insertion / extraction path, thus resulting in high internal resistance in Example 5. However, the battery in Example 5 exhibits good rate performance. In Example 8, the particles of the first electrode layer are too small, resulting in a large specific surface area and a small X / Y ratio. The numerous active sites easily lead to side reactions with the electrolyte, causing a certain degree of decrease in the cycle performance of Example 8. Therefore, further optimization of the particle size range, particle size ratio, and areal density ratio of the active materials between the first and second electrode layers can improve the battery's electrical performance.

[0082] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification can be used to interpret the scope of the claims.

Claims

1. An electrode, characterized in that, It includes a current collector, a first electrode layer, and a second electrode layer stacked in sequence; The material of the first electrode layer includes D v50 The first active material is X, and the material of the second electrode layer includes D. v50 X is the second active material of Y, where X is 4μm~8μm and Y is 10μm~20μm and 1 / 3≤X / Y<1.

2. The electrode as described in claim 1, characterized in that, The areal density ratio of the first electrode layer and the second electrode layer is (1~9): (1~9).

3. The electrode as described in claim 1 or 2, characterized in that, The first electrode layer satisfies one or more of the following conditions: (1) D of the first active material v50 The thickness is 5μm to 6μm; (2) The specific surface area of ​​the first active material is 1.5 m². 2 / g~2.5m 2 / g; (3) The material composition of the first electrode layer includes, by mass percentage, 95.5% to 97.5% of the first active material, 0.3% to 0.5% of the first conductive agent, and 1.8% to 4% of the first auxiliary agent; (4) The compaction density of the first electrode layer is 1.45 g / cc to 1.55 g / cc.

4. The electrode as described in claim 3, characterized in that, One or two of the following conditions must be met: (1) The first additive includes a first dispersant and a first binder. The material composition of the first electrode layer includes, by mass percentage, 95.5% to 97.5% of the first active material, 0.3% to 0.5% of the first conductive agent, 0.5% to 0.7% of the first dispersant and 1.3% to 3.7% of the first binder; (2) The first active material includes one or more of carbon materials and silicon materials.

5. The electrode as described in claim 1 or 2, characterized in that, The second electrode layer satisfies one or more of the following conditions: (1) D of the second active material v50 The thickness is 12μm~15μm; (2) The specific surface area of ​​the second active material is 1m². 2 / g~2 m 2 / g; (3) The material composition of the second electrode layer includes, by mass percentage, 95.5% to 97.5% of the second active material, 0.3% to 0.5% of the second conductive agent, and 1.8% to 5% of the second auxiliary agent; (4) The compaction density of the second electrode layer is 1.58 g / cc to 1.65 g / cc.

6. The electrode as described in claim 5, characterized in that, The second active material includes a central active material and a coating layer covering the central active material, wherein the material of the coating layer is 1% to 5% of the mass of the central active material.

7. The electrode as claimed in claim 6, characterized in that, One or more of the following conditions must be met: (1) The material of the coating layer includes one or more of asphalt, resin materials and hard carbon materials; (2) The second additive includes a second dispersant and a second binder. The material composition of the second electrode layer includes, by mass percentage, 95.5% to 97.5% of the second active material, 0.3% to 0.5% of the second conductive agent, 0.5% to 0.7% of the second dispersant and 1.3% to 3.7% of the second binder; (3) The central active material includes one or both of carbon materials and silicon materials.

8. The electrode according to any one of claims 1, 2, 4, 6, and 7, characterized in that, The current collector includes copper foil, aluminum foil, nickel foil, or a polymer-metal composite current collector.

9. The electrode as claimed in claim 8, characterized in that, The thickness of the current collector is 4.5 μm to 8 μm.

10. A lithium-ion battery, characterized in that, The device includes a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is disposed between the positive electrode and the negative electrode. The positive electrode, the negative electrode, and the separator are immersed in the electrolyte. The negative electrode includes an electrode as described in any one of claims 1 to 9.

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