Electrochemical device and electronic device

Abstract

The present application relates to an electrochemical device and an electronic device including the electrochemical device. The electrochemical device of the present application includes a negative electrode, and the negative electrode includes a porous carbon material layer and a negative electrode active material layer; wherein, the porous carbon material layer includes porous carbon material particles, and the porous carbon material particles include at least two types of pores among micropores, mesopores and macropores, and the at least two types of pores are interconnected, the pore diameter of the micropores < 2 nm, 2 nm ≤ the pore diameter of the mesopores ≤ 50 nm, 50 nm < the pore diameter of the macropores ≤ 500 nm. The electrochemical device of the present application has excellent high-rate charging performance and cycling performance.

Description

Technical Field

[0001] This application relates to the field of energy storage, and particularly to an electrochemical device and an electronic device. Background Art

[0002] Lithium-ion batteries have many advantages such as high energy density, long cycle life, low self-discharge, no memory effect, and environmental friendliness, and have been widely used in consumer electronics fields such as smart phones, smart bracelets, digital cameras, and laptop computers. A lithium-ion battery mainly consists of a positive electrode, a negative electrode, an electrolyte, a separator, etc. Among them, the selection of the negative electrode material is directly related to the energy density and fast charging performance of the battery. Currently, the negative electrode materials include metallic lithium, graphite, soft carbon, hard carbon, and alloy materials such as silicon-tin. Graphite occupies the main market of the negative electrode materials for lithium-ion batteries due to its comprehensive advantages such as low and stable lithium intercalation potential (0.01V to 0.2V), stable cycle performance, low cost, and environmental friendliness. However, the theoretical specific capacity of graphite is relatively low (372 mA·h / g), and at the same time, due to anisotropy, it is not conducive to the intercalation of lithium ions from all directions, which limits the intercalation speed of lithium ions. Restricted by the material structure characteristics, the specific capacity of graphite materials gradually approaches the limit value, and the rate or fast charging performance can no longer meet the increasing performance requirements of downstream products for electrode assemblies. Summary of the Invention

[0003] Aiming at the problems existing in the prior art, this application provides an electrochemical device, which has excellent high-rate charging performance and good cycle performance.

[0004] In the first aspect of this application, an electrochemical device is provided. The electrochemical device includes a negative electrode, and the negative electrode includes a porous carbon material layer and a negative electrode active material layer. Among them, the porous carbon material layer includes porous carbon material particles, and the porous carbon material particles include at least two types of pores among micropores, mesopores, and macropores, and at least two types of pores communicate with each other. The pore diameter of the micropores < 2nm, 2nm ≤ the pore diameter of the mesopores ≤ 50nm, 50nm < the pore diameter of the macropores ≤ 500nm.

[0005] The porous carbon material particles in the porous carbon material layer of this application have a composite pore structure with two or more levels, such as micropore-mesopore, micropore-mesopore-macropore, micropore-macropore, etc. At least part of different types of pores communicate with each other, enabling lithium ions to diffuse through macropores and mesopores. The diffusion channels of macropores and mesopores are wide, which can reduce the diffusion resistance of lithium ions entering the micropores, thereby improving the problem of lithium deposition on the surface of the high-capacity active material layer, effectively enhancing the high-rate fast charging performance of the electrochemical device, and realizing the beneficial combination of high capacity, high energy density, and fast charging performance.

[0006] According to some embodiments of the present application, the porous carbon material particles include micropores and mesopores, and the micropores and mesopores are at least partially interconnected. According to some embodiments of the present application, the porous carbon material particles include micropores and macropores, and the micropores and macropores are interconnected. According to some embodiments of the present application, the porous carbon material particles include mesopores and macropores, and the mesopores and macropores are interconnected. According to some embodiments of the present application, the porous carbon material particles include micropores, mesopores and macropores, wherein the micropores, mesopores and macropores are interconnected, that is, the micropores and mesopores are interconnected, the micropores and macropores are interconnected, and the macropores and mesopores are interconnected.

[0007] According to some embodiments of the present application, V1 / (V1 + V2 + V3) ≤ 20%, where V1 cm 3 / g is the micropore volume of the porous carbon material particles, and V2 cm 3 / g is the mesopore volume of the porous carbon material particles, and V3 cm 3 / g is the macropore volume of the porous carbon material particles. In the present application, when V1 / (V1 + V2 + V3) ≤ 20%, the proportion of lithium storage sites in the micropore part decreases. Compared with hard carbon, the porous carbon material particles do not have an obvious low-voltage plateau and are not prone to lithium dendrite generation under high-current charging conditions. In some embodiments of the present application, 1% < V1 / (V1 + V2 + V3) < 20%. In some embodiments of the present application, V1 / (V1 + V2 + V3) < 10%.

[0008] According to some embodiments of the present application, the negative electrode active material layer includes negative electrode active material particles, and the negative electrode active material particles include at least two types of pores among micropores, mesopores and macropores, and satisfy V1 / (V1 + V2 + V3) < P1 / (P1 + P2 + P3), where the pore diameter of the micropores < 2 nm, 2 nm ≤ the pore diameter of the mesopores ≤ 50 nm, 50 nm < the pore diameter of the macropores ≤ 500 nm, V1 cm 3 / g is the micropore volume of the porous carbon material particles, and V2 cm 3 / g is the mesopore volume of the porous carbon material particles, and V3 cm 3 / g is the macropore volume of the porous carbon material particles; P1 cm 3 / g is the micropore volume of the negative electrode active material particles, and P2 cm 3 / g is the mesopore volume of the negative electrode active material particles, and P3 cm 3 / g is the macropore volume of the negative electrode active material particles.

[0009] In the present application, the proportion of the micropores of the porous carbon material particles is smaller than the proportion of the micropores of the negative electrode active material particles, which is beneficial to the diffusion of lithium ions from the porous carbon material layer to the negative electrode active material layer and improves the lithium deposition on the surface of the negative electrode sheet. When the proportion of the micropores of the porous carbon material particles is too large, it is not conducive to the diffusion of lithium ions to the negative electrode active material layer, resulting in lithium deposition.

[0010] According to some embodiments of the present application, P1 / (P1 + P2 + P3) > 25%. Controlling the proportion of micropores in the negative electrode active material particles is beneficial to balancing the lithium storage capacity, as well as the ion diffusion rate and fast charging ability.

[0011] According to some embodiments of the present application, the negative electrode satisfies at least one of the following conditions (a) to (d):

[0012] (a) The coating mass per unit area of the porous carbon material layer is less than the coating mass per unit area of the negative electrode active material layer;

[0013] (b) The thickness of the porous carbon material layer is less than the thickness of the negative electrode active material layer;

[0014] (c) The porous carbon material particles include at least one of activated carbon, hard carbon, soft carbon, carbon fiber, or carbon nanotube;

[0015] (d) The negative electrode active material layer includes negative electrode active material particles, and the negative electrode active material particles include at least one of hard carbon or graphite.

[0016] According to some embodiments of the present application, the coating mass per unit area of the porous carbon material layer is less than the coating mass per unit area of the negative electrode active material layer. The tap density is one of the key parameters affecting the volumetric energy density of the electrode assembly. In order to meet a higher volumetric energy density, the electrode sheet should have a larger tap density. In the present application, the mass of the porous carbon material layer is less than the mass of the negative electrode active material layer, which is beneficial to improving the overall tap density of the composite layer (the porous carbon material layer and the negative electrode active material layer), while reducing the impact on the fast charging performance and cycling performance of the electrochemical device. In some embodiments of the present application, the porous carbon material layer includes porous carbon material particles, and the negative electrode active material layer includes hard carbon. The porous carbon material layer uses a porous carbon material with a hierarchical pore structure and at least partial penetration between various types of pores, and lithium ions can diffuse through macropores and mesopores. The diffusion channels of macropores and mesopores are wide, reducing the diffusion resistance of lithium ions entering the micropores, which is beneficial to high-rate fast charging performance and delays the lithium deposition on the surface of the electrode sheet. Therefore, the porous carbon material layer is superior to the hard carbon layer of the negative electrode active material in terms of diffusion kinetics or fast charging performance, greatly improving the fast charging lithium deposition problem of a single-layer hard carbon negative electrode in applications, and achieving a beneficial combination of high capacity, high energy density, and fast charging performance. In addition, the improvement of the lithium deposition problem on the surface of the electrode sheet, in addition to enhancing the fast charging performance, is also beneficial to suppressing the deformation of the electrode assembly and improving the appearance and safety performance of the electrochemical device.

[0017] According to some embodiments of the present application, the negative electrode further includes a negative electrode current collector, and the negative electrode active material layer is located between the porous carbon material layer and the negative electrode current collector.

[0018] According to some embodiments of the present application, the negative electrode further includes a conductive layer located between the negative electrode active material layer and the negative electrode current collector. In some embodiments, the conductive layer includes a conductive material, and the conductive material includes at least one of conductive carbon black, carbon nanofibers, carbon nanotubes, or graphene. Disposing a conductive layer between the negative electrode active material layer and the negative electrode current collector can improve the adhesion between the negative electrode active layer and the negative electrode current collector and improve the conductive contact.

[0019] According to some embodiments of the present application, the electrochemical device of the present application further includes a separator membrane, and a porous carbon material layer is located between the separator membrane and the negative electrode active material layer.

[0020] According to some embodiments of the present application, the electrochemical device of the present application further includes a separator membrane, and the porous carbon material layer is in contact with the separator membrane.

[0021] The second aspect of the present application provides an electronic device, which includes the electrochemical device of the first aspect.

[0022] By providing a porous carbon material layer on the negative electrode in the present application and utilizing the special pore structure of the porous carbon material particles, the diffusion of lithium ions in the negative electrode active material layer is effectively enhanced, the problem that lithium is easily deposited on the surface of the high-capacity negative electrode active material layer at a high charging rate is improved, the lithium deposition on the negative electrode sheet is reduced, the high-rate fast charging performance of the electrochemical device is effectively improved, and the beneficial combination of high capacity, high energy density and fast charging performance is realized. In addition, the improvement of the lithium deposition problem on the surface of the electrode sheet not only improves the fast charging performance, but also helps to suppress the deformation of the electrode assembly and improves the appearance and safety performance of the electrochemical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a negative electrode sheet according to some embodiments of the present application, where 1 is a porous carbon material layer, 2 is an active material layer, and 3 is a current collector.

[0024] Figure 2 It is a schematic structural diagram of a wound lithium-ion battery according to some embodiments of the present application, where 4 is a positive electrode, 5 is a separator membrane, 6 is a negative electrode, 7 is a positive electrode tab; 8 is a negative electrode tab.

[0025] Figure 3 For Figure 2 An enlarged view of part A in, where 61 is a porous carbon material layer, 62 is a negative electrode active material layer, and 63 is a negative electrode current collector.

[0026] Figure 4 Shows the charge curve of the hard carbon material of the negative electrode in Example 1 of the present application.

[0027] Figure 5Shows the charging curve of the porous carbon material of the negative electrode in Embodiment 1 of the present application.

[0028] Figure 6 Is a schematic structural diagram of porous carbon material particles according to some embodiments of the present application. Detailed Description

[0029] Embodiments of the present application will be described in detail below. Embodiments of the present application should not be construed as limiting the present application.

[0030] As used herein, the term "about" is used to describe and account for small variations. When used in conjunction with an event or circumstance, the term can refer to instances where the event or circumstance occurs precisely as well as instances where it occurs approximately. For example, when used in conjunction with a numerical value, the term can refer to a range of variation of ±10% less than or equal to the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. Additionally, sometimes quantities, ratios, and other numerical values are presented in a range format in this document. It should be understood that such range formats are for convenience and brevity and should be interpreted flexibly to include not only the explicitly specified numerical values as range limits but also all individual numerical values or sub-ranges subsumed within the range as if each numerical value and sub-range were explicitly specified.

[0031] A list of items joined by the phrase "at least one of" can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A can include a single element or multiple elements. Item B can include a single element or multiple elements. Item C can include a single element or multiple elements.

[0032] References to "embodiments", "some embodiments", "one embodiment", "another example", "example", "specific example", or "partial example" throughout the specification mean that at least one embodiment or example in this application includes the specific features, structures, materials, or characteristics described in that embodiment or example. Thus, descriptions such as "in some embodiments", "in embodiments", "in one embodiment", "in another example", "in an example", "in a specific example", or "example" that appear throughout the specification do not necessarily refer to the same embodiments or examples in this application. In addition, the specific features, structures, materials, or characteristics herein can be combined in one or more embodiments or examples in any suitable manner.

[0033] A first aspect of the present application provides an electrochemical device, which includes a negative electrode, and the negative electrode includes a porous carbon material layer and a negative electrode active material layer. Among them, the porous carbon material layer includes porous carbon material particles, and the porous carbon material particles include at least two types of pores among micropores, mesopores, and macropores, and at least two types of pores communicate with each other. The pore diameter of the micropores <2 nm, 2 nm ≤ the pore diameter of the mesopores ≤ 50 nm, and 50 nm < the pore diameter of the macropores ≤ 500 nm.

[0034] The porous carbon material particles in the porous carbon material layer of the present application have a composite pore structure with two or more levels, such as micropore-mesopore, micropore-mesopore-macropore, micropore-macropore, etc. At least part of different types of pores communicate with each other, so that lithium ions can diffuse through the macropores and mesopores. The diffusion channels of the macropores and mesopores are wide, which can reduce the diffusion resistance of lithium ions entering the micropores, thereby improving the problem of lithium deposition on the surface of the high-capacity negative electrode active material layer, effectively enhancing the high-rate fast charging performance of the electrochemical device, and achieving a beneficial combination of high capacity, high energy density, and fast charging performance.

[0035] According to some embodiments of the present application, the porous carbon material particles include micropores and mesopores, and at least part of the micropores and mesopores communicate with each other. According to some embodiments of the present application, the porous carbon material particles include micropores and macropores, and at least part of the micropores and macropores communicate with each other. According to some embodiments of the present application, the porous carbon material particles include mesopores and macropores, and at least part of the mesopores and macropores communicate with each other. According to some embodiments of the present application, the porous carbon material particles include micropores, mesopores, and macropores, wherein at least part of the micropores, mesopores, and macropores communicate with each other, that is, at least part of the micropores and mesopores communicate with each other, at least part of the micropores and macropores communicate with each other, and at least part of the macropores and mesopores communicate with each other.

[0036] It should be understood that in the present application, micropores can also communicate with each other, mesopores can also communicate with each other, and macropores can also communicate with each other.

[0037] According to some embodiments of the present application, at least 50% of the at least two types of pores are interconnected, for example, at least 60%, at least 70%, at least 80%, or at least 90% are interconnected.

[0038] According to some embodiments of the present application, the pore diameter D1 of the micropores < 2 nm. According to some embodiments of the present application, the pore diameter D2 of the mesopores satisfies 2 nm ≤ D2 ≤ 50 nm. According to some embodiments of the present application, the pore diameter D3 of the macropores satisfies 50 nm < D3 ≤ 500 nm.

[0039] According to some embodiments of the present application, V1 / (V1 + V2 + V3) ≤ 20%, where V1 cm 3 / g is the micropore volume of a single porous carbon material particle, V2 cm 3 / g is the mesopore volume of a single porous carbon material particle, V3 cm 3 / g is the macropore volume of a single porous carbon material particle. According to some embodiments of the present application, V1 / (V1 + V2 + V3) is 2%, 4%, 6%, 8%, 11%, 13%, 15%, 17%, 19%, or a range composed of any two of these values.

[0040] In the present application, when V1 / (V1 + V2 + V3) ≤ 20%, the proportion of lithium storage sites in the micropore part decreases. Compared with hard carbon, the porous carbon material particles do not have an obvious low-voltage plateau and are not prone to lithium dendrite generation under high-current charging conditions. In some embodiments of the present application, 1% < V1 / (V1 + V2 + V3) < 20%. In some embodiments of the present application, V1 / (V1 + V2 + V3) < 10%.

[0041] According to some embodiments of the present application, the negative electrode active material layer includes negative electrode active material particles, and the negative electrode active material particles include at least two types of pores among micropores, mesopores, and macropores, and satisfy V1 / (V1 + V2 + V3) < P1 / (P1 + P2 + P3), where the pore diameter of the micropores < 2 nm, 2 nm ≤ the pore diameter of the mesopores ≤ 50 nm, 50 nm < the pore diameter of the macropores ≤ 500 nm, V1 cm 3 / g is the micropore volume of a single porous carbon material particle, V2 cm 3 / g is the mesopore volume of a single porous carbon material particle, V3 cm 3 / g is the macropore volume of a single porous carbon material particle; P1 cm 3 / g is the micropore volume of a single negative electrode active material particle, P2 cm 3 / g is the mesopore volume of a single negative electrode active material particle, P3 cm 3 / g is the macropore volume of a single negative electrode active material particle.

[0042] In the present application, the proportion of micropores in the porous carbon material particles is less than that in the negative electrode active material particles, which is beneficial to the diffusion of lithium ions from the porous carbon material layer to the negative electrode active material layer, thereby improving the lithium deposition on the surface of the electrode sheet. When the proportion of micropores in the porous carbon material particles is too large, it is not conducive to the diffusion of lithium ions to the negative electrode active material layer, resulting in lithium deposition.

[0043] According to some embodiments of the present application, P1 / (P1 + P2 + P3) > 25%. When the proportion of micropores in the negative electrode active material particles is too large, it is beneficial to improve the lithium storage capacity, but it is not conducive to the diffusion of lithium ions and fast charging. According to some embodiments of the present application, P1 / (P1 + P2 + P3) is 27%, 28%, 29%, 30%, 31%, 32%, 33%, 35%, 37%, 39% or the range composed of any two of these values.

[0044] According to some embodiments of the present application, the coating mass per unit area of the porous carbon material layer is less than that of the negative electrode active material layer. In some embodiments of the present application, the thickness of the porous carbon material layer is less than that of the negative electrode active material layer. The compaction density is one of the key parameters affecting the volume energy density of the electrode assembly. In order to meet a higher volume energy density, the electrode sheet can be set with a larger compaction density. In the present application, the mass of the porous carbon material layer is less than that of the negative electrode active material layer, which is beneficial to improving the overall compaction density of the composite layer and at the same time reducing the impact on the fast charging performance and cycling performance of the electrochemical device. Lithium deposition mainly occurs on the surface of the electrode sheet. Therefore, the porous carbon material layer on the surface can thinly cover the negative electrode active material layer. When the coating mass of the porous carbon material layer is higher than that of the negative electrode active material layer, it may reduce the overall compaction density of the composite layer.

[0045] According to some embodiments of the present application, the porous carbon material particles include at least one of activated carbon, hard carbon, soft carbon, carbon fiber or carbon nanotube.

[0046] According to some embodiments of the present application, the negative electrode active material layer includes negative electrode active material particles. In some embodiments, the negative electrode active material particles include at least one of hard carbon or graphite.

[0047] In the present application, the negative electrode active material particles refer to materials that can embed and extract lithium ions. It should be understood that for the convenience of description in the present application, the porous carbon material layer, porous carbon material particles, negative electrode active material layer and negative electrode active material particles are defined, but the porous carbon material particles may also have the characteristics of embedding and extracting lithium ions.

[0048] Under high-rate charging conditions, since it is generally difficult for conventional single-layer graphite anodes or single-layer hard carbon anodes to quickly complete lithium intercalation, lithium metal deposition is likely to occur on the surface of the electrode. Compared with graphite, hard carbon has a higher reversible specific capacity, generally ranging from 500 mAh / g to 1000 mAh / g. However, more than half of the lithium storage capacity of hard carbon materials comes from the low-voltage plateau part (0.1V - 0V, vs. Li + / Li), which is close to the Li / Li + redox potential, and the voltage plateau is closer to the lithium deposition potential compared to that of graphite. Therefore, under high-current charging conditions, lithium dendrites are more likely to precipitate on the hard carbon electrode than on the graphite electrode, and the high-rate charging performance of hard carbon is limited in practical applications. In addition, the lithium dendrites deposited on the surface of the hard carbon anode can also cause local deformation of the electrode assembly and even pose safety problems. In this application, a porous carbon material layer is laminated on the surface of the negative electrode active material layer. By utilizing the special pore structure of the porous carbon material particles, the diffusion of lithium ions is enhanced, effectively improving the lithium deposition problem of single-layer hard carbon or graphite anodes in applications.

[0049] In some embodiments of the present application, the porous carbon material layer comprises porous carbon material particles, and the negative electrode active material layer comprises hard carbon. The porous carbon material layer adopts porous carbon material particles with a hierarchical pore structure in which at least some of the pores of each type communicate with each other. Lithium ions can diffuse through the macropores and mesopores. The diffusion channels of macropores and mesopores are wide, reducing the diffusion resistance of lithium ions entering the micropores, which is beneficial to high-rate fast charging performance and delays lithium deposition on the electrode surface. Therefore, the porous carbon material particles are significantly superior to the hard carbon layer of the negative electrode active material in terms of diffusion kinetics or fast charging performance, greatly improving the shortcoming of fast charging and lithium deposition of single-layer hard carbon anodes in applications, and achieving a beneficial combination of high capacity, high energy density, and fast charging performance. In addition, the improvement of the lithium deposition problem on the electrode surface not only enhances the fast charging performance but also helps to suppress the deformation of the electrode assembly and improve the appearance and safety performance of the electrochemical device.

[0050] According to some embodiments of the present application, the negative electrode further comprises a negative electrode current collector, and the negative electrode active material layer is located between the porous carbon material layer and the negative electrode current collector. As Figure 1 shown, some embodiments of the present application provide a negative electrode. The negative electrode sheet comprises a negative electrode current collector, a porous carbon material layer (the first layer), and a negative electrode active material layer (the second layer). It should be understood that although Figure 1 the first layer and the second layer are shown as being disposed on one side of the negative electrode current collector, this is merely exemplary, and the first layer and the second layer can also be disposed on both sides of the negative electrode current collector.

[0051] According to some embodiments of the present application, the negative electrode further includes a conductive layer located between the negative electrode active material layer and the negative electrode current collector. In some embodiments, the conductive layer includes a conductive material, and the conductive material includes at least one of conductive carbon black, carbon nanofibers, carbon nanotubes, or graphene. Providing a conductive layer between the negative electrode active material layer and the negative electrode current collector can improve the adhesion between the negative electrode active material layer and the negative electrode current collector and improve the conductive contact.

[0052] According to some embodiments of the present application, the electrochemical device of the present application further includes a separator membrane, and a porous carbon material layer is located between the separator membrane and the negative electrode active material layer. According to some embodiments of the present application, the electrochemical device of the present application further includes a separator membrane, and the porous carbon material layer is in contact with the separator membrane.

[0053] According to some embodiments of the present application, the porous carbon material layer and the negative electrode active material layer each independently further include a conductive agent and / or a binder. In some embodiments, the conductive agent includes at least one of conductive carbon black, acetylene black, carbon nanotubes, Ketjen black, conductive graphite, or graphene. In some embodiments, the mass percentage of the conductive agent in the porous carbon material layer or the negative electrode active material layer is 0.5% to 10%. In some embodiments, the binder includes at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride - hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate salt, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyethylene ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, or styrene - butadiene rubber. In some embodiments, the mass percentage of the binder in the porous carbon material layer or the negative electrode active material layer is 0.5% to 10%.

[0054] The negative electrode of the present application can be prepared by known methods in the art. Generally, negative electrode active material particles and optional conductive agents (such as carbon materials like carbon black and metal particles, etc.), binders (such as SBR), and other optional additives (such as PTC thermistor materials) are mixed and dispersed in a solvent (such as deionized water), stirred evenly and then uniformly coated on the negative electrode current collector, and after drying, a negative electrode containing a negative electrode active material layer is obtained. Then, porous carbon material particles and optional conductive agents (such as carbon materials like carbon black and metal particles, etc.), binders (such as SBR), and other optional additives (such as PTC thermistor materials) are mixed and dispersed in a solvent (such as deionized water), stirred evenly and then uniformly coated on the negative electrode active material layer, and a negative electrode containing a porous carbon material layer and a negative electrode active material layer can be obtained. Materials such as metal foil or porous metal plates can be used as the negative electrode current collector.

[0055] According to some embodiments of the present application, the electrochemical device of the present application further includes a positive electrode. The material particles, composition, and manufacturing method of the positive electrode that can be used in the embodiments of the present application include the technologies disclosed in any prior art.

[0056] According to some embodiments of the present application, the positive electrode includes a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector. According to some embodiments of the present application, the positive electrode active material particles include, but are not limited to: at least one of lithium cobalt oxide (LiCoO₂), lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide (NCA), lithium iron phosphate (LiFePO₄), or lithium manganese oxide (LiMn₂O₄).

[0057] According to some embodiments of the present application, the positive electrode active material layer further includes a binder, and optionally includes a conductive material. The binder improves the binding between the positive electrode active material particles and also improves the binding between the positive electrode active material and the positive electrode current collector. In some embodiments, the binder includes: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1-difluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, or nylon, etc.

[0058] According to some embodiments of the present application, the conductive material includes, but is not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof. In some embodiments, the carbon-based materials are selected from carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotube, or any combination thereof. In some embodiments, the metal-based materials are selected from copper, nickel, aluminum, or silver. In some embodiments, the conductive polymer is a polyphenylene derivative.

[0059] According to some embodiments of the present application, the positive electrode current collector may include, but is not limited to, aluminum.

[0060] According to some embodiments of the present application, the electrochemical device of the present application further includes an electrolyte. The electrolyte that can be used in the embodiments of the present application can be an electrolyte known in the prior art.

[0061] In some embodiments, the electrolyte includes an organic solvent, a lithium salt, and an additive. The organic solvent of the electrolyte according to the present application can be any organic solvent known in the prior art that can be used as a solvent for the electrolyte. There is no limitation on the electrolyte used in the electrolyte according to the present application, and it can be any electrolyte known in the prior art. The additive of the electrolyte according to the present application can be any additive known in the prior art that can be used as an electrolyte additive.

[0062] In some embodiments, the organic solvent includes, but is not limited to: ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), propylene carbonate, or ethyl propionate.

[0063] In some embodiments, the lithium salt includes, but is not limited to: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), lithium bis(trifluoromethanesulfonyl)imide LiN(CF3SO2)2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO2F)2) (LiFSI), lithium bis(oxalato)borate LiB(C2O4)2 (LiBOB), or lithium difluoro(oxalato)borate LiBF2(C2O4) (LiDFOB).

[0064] In some embodiments, the concentration of the lithium salt in the electrolyte is: about 0.5 mol / L to 3 mol / L, about 0.5 mol / L to 2 mol / L, or about 0.8 mol / L to 1.5 mol / L.

[0065] The material and shape of the separator used in the electrochemical device of the present application are not particularly limited, and it can be any technology disclosed in the prior art. In some embodiments, the separator includes a polymer or an inorganic substance formed of a material stable to the electrolyte of the present application.

[0066] For example, the separator may include a base material layer and a surface treatment layer. The base material layer is a non-woven fabric, a film, or a composite film having a porous structure, and the material of the base material layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate, and polyimide. Specifically, a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be selected.

[0067] A surface treatment layer is provided on at least one surface of the base material layer, and the surface treatment layer can be a polymer layer, an inorganic layer, or a layer formed by mixing a polymer and an inorganic substance.

[0068] The inorganic layer includes inorganic particles and a binder, and the inorganic particles are selected from at least one of alumina, silica, magnesia, titania, hafnium dioxide, tin dioxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. The binder is selected from at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate salt, polyvinyl pyrrolidone, polyethylene alkoxide, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene.

[0069] The polymer layer contains a polymer, and the material of the polymer is selected from at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl alkoxide, polyvinylidene fluoride, and poly(vinylidene fluoride - hexafluoropropylene).

[0070] The electrochemical device of the present application includes any device that undergoes an electrochemical reaction, and specific examples thereof include all kinds of primary batteries and secondary batteries. In particular, the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.

[0071] The second aspect of the present application provides an electronic device, which includes the electrochemical device of the first aspect.

[0072] The electronic device or apparatus of the present application is not particularly limited. In some embodiments, the electronic device of the present application includes, but is not limited to, a laptop computer, a pen input computer, a mobile computer, an e - book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a headset stereo, a video recorder, a liquid crystal TV, a portable cleaner, a portable CD player, a minidisc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power source, a motor, an automobile, a motorcycle, a moped, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flash, a camera, a large household battery, and a lithium ion capacitor, etc.

[0073] The present application will be further described below in conjunction with embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application.

[0074] Test Method

[0075] 1. Testing of material pore size distribution and pore volume

[0076] (1) Sample pretreatment

[0077] Porous carbon material particles:

[0078] a. Take a fully discharged lithium - ion battery, disassemble the negative electrode sheet from each one separately, wash, dry, scrape off the powder on the surface layer (about 10 μm thick) of the electrode sheet, and heat - treat the scraped powder in a tube furnace at 400 °C for 4 h under argon protection to remove the binder adhered to the material surface, and then bake the obtained material sample at 150 °C for 12 h;

[0079] Or b. Bake the porous carbon material sample at 150 °C for 12 h.

[0080] Negative electrode active material particles:

[0081] a. Take fully discharged lithium-ion batteries, disassemble the negative electrode sheets separately, clean, dry, scrape off the powder on the side of the electrode sheet close to the current collector (about 10 μm thick), and heat-treat the scraped powder in a tubular furnace at 400 °C for 4 h under argon protection to remove the binder adhered to the material surface. Then, bake the obtained material sample at 150 °C for 12 h;

[0082] Or b. Bake the active material sample at 150 °C for 12 h.

[0083] (2) Test method

[0084] Place the material sample treated in (1) in a gas adsorption analyzer and test at -196 °C to obtain the isothermal adsorption and desorption curve. The volume of N2 gas at an adsorption relative pressure of 0.99 is equivalent to the total pore volume.

[0085] In the micropore range, the volume distribution corresponding to different pore diameters is obtained by analyzing the isothermal adsorption curve with the Horvath-Kawazoe (HK) method.

[0086] The HK expression for slit-shaped micropores is:

[0087]

[0088] The HK expression for cylindrical micropores is:

[0089]

[0090] In the formula

[0091] R—Gas constant;

[0092] P—Adsorption equilibrium pressure, mmHg;

[0093] P0—Saturated vapor pressure of the adsorbate at the adsorption temperature, mmHg;

[0094] K—Avogadro constant;

[0095] Ns—Number of atoms per unit area of the adsorbent, atoms / cm 2 ;

[0096] N A —Number of atoms per unit area of the adsorbate, atoms / cm 2 ;

[0097] As, A A —Lennard-Jones potential constants of the adsorbent and the adsorbate;

[0098] σ—Nuclear distance between the gas atom and the surface at zero interaction energy;

[0099] l—The nuclear spacing between two planar layers of slit pores;

[0100] d—The sum of the diameters of the adsorbent atoms and the adsorbate atoms;

[0101] r P —The radius of the cylindrical micropore;

[0102] α k 、β k —Calculated from the r function of k derived by Everett and Powl. By selecting the applicable range of the effective pore size, the micropore distribution can be calculated using the HK equation for the adsorption curve measured by the adsorber within the corresponding relative pressure range, and the adsorption amount corresponding to each micropore aperture can be obtained.

[0103] In the mesopore and macropore ranges, for the pore volume corresponding to different pore sizes, the nitrogen adsorption - desorption curve is analyzed by the Barrett - Joyner - Halenda (BJH) method to obtain the integral distribution of the pore volume varying with the pore size. The pore size analysis of mesopores and macropores is based on macroscopic thermodynamics, mainly relying on the capillary condensation theory. The calculation method is to determine the pore size corresponding to the pressure using the Kelvin equation, calculate the adsorption layer thickness using the Halsey equation, and assume that the nitrogen molecules adsorbed in the pores exist in the density of liquid nitrogen; through the measured isothermal adsorption - desorption curve (usually the relative pressure range is 10 -4 to 0.995), the pore volume - pore size distribution, the total pore volume, and the average pore size are calculated by the successive calculation method.

[0104] Whether the pores are through - connected is analyzed by high - resolution transmission electron microscopy (TEM, equipment model is Talos F200X), and the operating voltage is 120 kV. For the through - connection ratio, the ratio is obtained by the statistical method. Representative regions of the electron - magnified images are selected, and the proportion of the number of through - connected pores is statistically analyzed. More than 10 representative regions are selected and the average value is taken.

[0105] 2. Lithium deposition test

[0106] In the constant - temperature chamber, the battery cell is charged to the full - charge voltage at different rates, then held at a constant voltage to 0.05C, and then discharged at 1C to the lower - limit voltage. After charging and discharging 10 times in the same process successively, the negative electrode plate is disassembled to observe whether lithium is deposited.

[0107] Determination of lithium deposition degree: It is determined according to the contaminated state of the separator film in contact with the negative electrode after full charge and disassembly. When the separator film in contact with the negative electrode shows white as a whole and the area showing gray is <2%, it is determined that there is no lithium deposition; when most of the separator film in contact with the negative electrode is white, but gray can be observed at some positions, and the gray area is between 2% and 20%, it is determined that there is slight lithium deposition; when part of the separator film in contact with the negative electrode is white, but part of the gray can still be clearly observed, and the gray area is between 20% and 60%, it is determined that there is lithium deposition; when most of the separator film in contact with the negative electrode shows gray and the gray area >60%, it is determined that there is severe lithium deposition.

[0108] 3. Cycle expansion rate test

[0109] In a constant temperature chamber, charge the battery cell to the full charge voltage at a certain rate, then keep the voltage constant at 0.05C, and then discharge it to the lower limit voltage at 1C. Charge and discharge 1000 times in the same process successively. The test method for the deformation amount of the battery cell during the cycle is: fix it on both sides of the battery cell with parallel clamping plates, apply a pressure of 700g, and measure the thickness of the battery cell. Cycle expansion rate = (final thickness - initial thickness) / initial thickness × 100%.

[0110] 4. Compaction density test

[0111] Compaction density = layer mass / layer thickness. Take multiple electrode sheet samples with the same area, obtain the substance on the coating side of the current collector in the electrode sheet, measure the mass of the coating on the current collector side in the electrode sheet; measure the thickness of the coating on the current collector side in the electrode sheet with the help of SEM, so as to calculate the compaction density of the coating.

[0112] Examples and comparative examples

[0113] Preparation of porous carbon material particles

[0114] The preparation of porous carbon material particles adopts the template method. The template (i.e., pore-forming agent) is used to form pores and control the pore size to form a porous carbon skeleton structure. The preparation steps include:

[0115] 1) Prepare a mixed solution of pore-forming agent and carbon source. After the solvent evaporates, the carbon source wraps the pore-forming agent. The pore-forming agent includes polymers, acidic compound particles, basic compound particles, etc. The carbon source includes polymers or biomass raw materials, etc.;

[0116] 2) Calcinate the carbon source wrapped with the pore-forming agent at a high temperature of 600°C to 1600°C under nitrogen protection, and the carbon source precursor is cracked into carbon materials;

[0117] 3) Wash the carbon materials with alkali or acid to remove the pore-forming agent;

[0118] 4) Perform post-treatments such as impurity removal, drying, grinding, and particle size screening on the powder after removing the pore-forming agent.

[0119] Among them, the size and addition amount of the pore-forming agent can control the size and proportion of macropores and mesopores. The through-structure between the hierarchical pores is mainly regulated by the uniformity of the distribution of pore-forming agents with different sizes. The carbonization temperature can control the proportion of micropores.

[0120] Example 1

[0121] 1. Preparation of the negative electrode sheet

[0122] After mixing hard carbon, styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) in a weight ratio of 97:2:1, a certain weight of deionized water is added, and the mixture is uniformly stirred to obtain a slurry. The slurry is coated on copper foil at a surface density of 60 mg / 1540 mm 2 and dried in vacuum at 80°C to serve as the second coating (negative electrode active material layer). Next, porous carbon material particles with a hierarchical pore structure, styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) are mixed in a weight ratio of 97:2:1, a certain weight of deionized water is added, and the mixture is uniformly stirred to obtain a slurry. The slurry is coated on the upper surface of the second coating at a surface density of 30 mg / 1540 mm 2 to form a composite coating with the first coating (porous carbon material layer) covering the second coating. After the composite coating is dried in vacuum at 80°C, it is cold-pressed, die-cut, and slit into negative electrode sheets. The Q-V curve of the lithium intercalation of the hard carbon material used in this example is as Figure 4 shown, and its micropore volume / total pore volume = 32%. The porous carbon material particles have a three-level structure of micropores-mesopores-macropores, and its Q-V curve is as Figure 5 shown, and its micropore volume / total pore volume (i.e., micropore pore volume + mesopore pore volume + macropore pore volume) = 6%.

[0123] 2. Preparation of the positive electrode sheet

[0124] Take the positive electrode active material LiCoO2, the binder polyvinylidene fluoride (PVDF), and acetylene black, mix them in a mass ratio of 98:1:1, add N-methylpyrrolidone (NMP), uniformly stir to obtain a slurry, coat it on aluminum foil at a certain surface density, and after drying in vacuum at 100°C, it is cold-pressed, die-cut, and slit into positive electrode sheets.

[0125] 3. Preparation of the lithium-ion battery

[0126] The positive electrode sheet, separator (PE porous polymer film), and negative electrode sheet are wound into a bare battery cell, which is then placed into an aluminum-plastic film bag and subjected to processes such as pre-packaging, baking, electrolyte injection, formation, degassing, and final sealing to produce a lithium-ion battery. The separator includes a base film, a ceramic layer, an adhesive layer, etc. The electrolyte composition includes lithium hexafluorophosphate and organic solvents. The concentration of lithium hexafluorophosphate is 1 mol / L, and the organic solvents include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), vinylene carbonate (VC), and fluoroethylene carbonate (FEC), where EC:PC:DEC:DMC:EMC:VC:FEC = 20:30:20:13:13:2:2.

[0127] Example 2

[0128] It is the same as the preparation method of Example 1, except that the micropore volume / total pore volume of the porous carbon material particles = 14%.

[0129] Example 3

[0130] It is the same as the preparation method of Example 1, except that the porous carbon material particles have a secondary structure of micropores / mesopores, and the micropore volume / total pore volume = 8%.

[0131] Example 4

[0132] It is the same as the preparation method of Example 1, except that the porous carbon material particles have a secondary structure of mesopores / macropores.

[0133] Example 5

[0134] It is the same as the preparation method of Example 1, except that the porous carbon material particles have a secondary structure of micropores / macropores, and the micropore volume / total pore volume = 8%.

[0135] Example 6

[0136] It is the same as the preparation method of Example 1, except that the active material of the second coating near the negative electrode current collector is graphite.

[0137] Example 7

[0138] It is the same as the preparation method of Example 1, except that the micropore volume / total pore volume of the porous carbon material particles = 20%.

[0139] Example 8

[0140] It is the same as the preparation method of Example 1, except that the micropore volume / total pore volume of the porous carbon material particles = 37%, and the ratio is higher than the micropore volume / total pore volume of hard carbon.

[0141] Example 9

[0142] The preparation method is the same as that of Example 1, except that the coating mass of the first coating is 50 mg / 1540 mm 2 , which is equal to the coating mass of the second coating.

[0143] Example 10

[0144] The preparation method is the same as that of Example 1, except that the coating mass of the first coating is 60 mg / 1540 mm 2 , which is greater than the coating mass of the second coating of 30 mg / 1540 mm 2 .

[0145] Comparative Example 1

[0146] The preparation method is the same as that of Example 1, except that it only includes a single-layer second coating close to the current collector, the second active material is hard carbon, and the coating mass is 90 mg / 1540 mm 2 .

[0147] Comparative Example 2

[0148] The preparation method is the same as that of Comparative Example 1, except that the second active material is graphite.

[0149] Comparative Example 3

[0150] The preparation method is the same as that of Example 1, except that the micropore / mesopore / macropore structure of the porous carbon material particles is not interconnected.

[0151] Comparative Example 4

[0152] The preparation method is the same as that of Example 3, except that the micropore / mesopore structure of the porous carbon material particles is not interconnected.

[0153] Comparative Example 5

[0154] The preparation method is the same as that of Example 4, except that the mesopore / macropore structure of the porous carbon material particles is not interconnected.

[0155] Comparative Example 6

[0156] The preparation method is the same as that of Example 5, except that the micropore / macropore structure of the porous carbon material is not interconnected.

[0157] Table 1

[0158]

[0159] Note: In the multi-pore carbon materials of Examples 1 to 8, the proportion of interconnected pores ≥ 70%

[0160] By comparing Example 1 and Comparative Example 1, as well as Example 6 and Comparative Example 2, it can be seen that the double-layer composite coating containing porous carbon material particles with a hierarchical pore structure of the present application is superior to a single hard carbon coating or graphite coating. The lithium-ion batteries of Example 1 and Example 6 do not lithium plate out during high-rate charging at 8C, while the lithium-ion batteries of Comparative Example 1 and Comparative Example 2 already lithium plate out at a charging rate of 6C. The cell cycle expansion rates of Example 1 and Example 6 are significantly lower than those of Comparative Example 1 and Comparative Example 2.

[0161] By comparing Examples 1 to 2 and Examples 7 to 8, it can be seen that the ratio of the micropore volume to the total pore volume of the porous carbon material particles with a hierarchical pore structure, that is, the proportion of micropores, has a significant impact on the fast charging lithium plating performance and cycle expansion performance of lithium-ion batteries. It is preferably that the micropore volume / total pore volume ≤ 20%, and more preferably the micropore volume / total pore volume < 10%.

[0162] By comparing Example 7 and Example 8, it can be seen that when the micropore volume / total pore volume of the porous carbon material particles with a hierarchical pore structure is higher than that of the hard carbon coating, it will deteriorate the lithium plating of the lithium-ion battery. The main reason is that the proportion of micropores in the first coating is too large, which is not conducive to the diffusion of lithium ions to the second coating. The surface layer material of the composite coating should be selected with a smaller proportion of micropores to improve the lithium ion diffusion process.

[0163] By comparing Example 1, Example 3, Example 4, Example 5 and Comparative Examples 3 to 6, it can be seen that whether it is a three-level structure (micropores, mesopores and macropores) or a two-level structure (micropores and mesopores, micropores and macropores, macropores and mesopores) of porous carbon material particles, at least partial interconnection of each level of pores is beneficial to avoiding fast charging lithium plating of lithium-ion batteries and significantly inhibiting cell cycle expansion. The main reason is that when lithium ions diffuse, they first enter the finer pore channels from the larger pore channels, which is beneficial to reducing the diffusion resistance. Therefore, a structure without interconnection of hierarchical pores is difficult to produce a similar improvement effect.

[0164] Table 2

[0165]

[0166] Note: The compaction density of the composite coating = (compaction density of the first coating × coating mass of the first coating + compaction density of the second coating × coating mass of the second coating) / (coating mass of the first coating + coating mass of the second coating)

[0167] The compaction density of the composite coating is one of the key parameters affecting the volumetric energy density of the battery cell. To meet a higher volumetric energy density, the electrode sheet can pursue a greater compaction density. By comparing Example 1 with Examples 9 and 10, it can be seen that since the compaction density of the first coating is lower than that of the second coating, and the compaction density of the coating is mainly determined by the material properties, increasing the coating amount of the second coating is beneficial to improving the overall compaction density of the composite coating without affecting the fast charging performance and the cycle expansion performance. Lithium deposition mainly occurs on the surface of the electrode sheet. Therefore, the first coating on the surface only needs to thinly cover the second coating without excessive coating. When the coating quality of the first coating is higher than that of the second coating, it instead reduces the overall compaction density of the composite coating.

[0168] Although the illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on the present application, and changes, substitutions, and modifications can be made to the embodiments without departing from the spirit, principles, and scope of the present application.

Claims

1. An electrochemical device, comprising a negative electrode, the negative electrode including a porous carbon material layer and a negative electrode active material layer; Among them, The porous carbon material layer includes porous carbon material particles, the porous carbon material particles including at least two of micropores, mesopores and macropores, and the at least two pores being interconnected, The pore diameter of the micropores < 2 nm, 2 nm ≤ the pore diameter of the mesopores ≤ 50 nm, 50 nm < the pore diameter of the macropores ≤ 500 nm, The negative electrode active material layer includes negative electrode active material particles, the negative electrode active material particles including at least two of the micropores, the mesopores and the macropores, and satisfying V1 / (V1 + V2 + V3) < P1 / (P1 + P2 + P3), V1 cm 3 / g is the micropore volume of the porous carbon material particles, V2 cm 3 / g is the mesopore volume of the porous carbon material particles, V3 cm 3 / g is the macropore volume of the porous carbon material particles; P1 cm 3 / g is the micropore volume of the negative electrode active material particles, P2 cm 3 / g is the mesopore volume of the negative electrode active material particles, P3 cm 3 / g is the macropore volume of the negative electrode active material particles; The negative electrode further includes a negative electrode current collector, and the negative electrode active material layer is located between the porous carbon material layer and the negative electrode current collector.

2. The electrochemical device according to claim 1, wherein, V1 / (V1 + V2 + V3) ≤ 20%.

3. The electrochemical device according to claim 2, wherein, V1 / (V1 + V2 + V3) ≤ 10%.

4. The electrochemical device according to claim 1, wherein, P1 / (P1 + P2 + P3) > 25%.

5. The electrochemical device according to claim 1, wherein, The negative electrode satisfies at least one of the following conditions (a) to (d): (a) The coating mass per unit area of the porous carbon material layer is less than the coating mass per unit area of the negative electrode active material layer; (b) The thickness of the porous carbon material layer is less than the thickness of the active material layer; (c) The porous carbon material particles include at least one of activated carbon, hard carbon, soft carbon, carbon fiber or carbon nanotube; (d) The negative electrode active material layer includes negative electrode active material particles, and the active material particles include at least one of hard carbon or graphite.

6. The electrochemical device according to claim 1, wherein, The negative electrode further includes a conductive layer located between the negative electrode active material layer and the negative electrode current collector.

7. The electrochemical device according to claim 1, wherein, The electrochemical device further includes a separator, and the porous carbon material layer is located between the separator and the negative electrode active material layer.

8. The electrochemical device according to claim 7, wherein, The porous carbon material layer is in contact with the separator.

9. An electronic device, comprising the electrochemical device according to any one of claims 1 to 8.

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