Carbon material, method for producing the same, conductive agent, electrode sheet, battery, and electric device

Abstract

The application belongs to the technical field of batteries, and particularly relates to a carbon material and a preparation method thereof, a conductive agent, a pole piece, a battery and a power utilization device. The carbon material comprises zero-dimensional structure carbon material; two-dimensional structure carbon material, which is located on the surface of the zero-dimensional structure carbon material, and the two-dimensional structure carbon material and the zero-dimensional structure carbon material are connected through a chemical bond. When the carbon material is used as a conductive agent for a pole piece, the two-dimensional structure carbon material is located on the surface of the zero-dimensional structure carbon material, the edge two-dimensional structure carbon material has higher lap joint efficiency, has better conductivity, and thus is conducive to improving the fast charging performance of the pole piece.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to carbon materials and their preparation methods, conductive agents, electrodes, batteries, and electrical devices. Background Technology

[0002] Currently, the main function of conductive agents added to battery electrodes is to provide more overlap and buffering for the active materials during shrinkage / expansion. To improve the conductivity of these agents, researchers have proposed modifying materials such as carbon black, carbon nanotubes, and graphene; however, in practical applications, the conductivity efficiency of these agents remains low. Therefore, technologies related to conductive agents still need improvement. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a carbon material with excellent electrical conductivity, its preparation method, a conductive agent, an electrode, a battery, and an electrical device.

[0004] In a first aspect, this application provides a carbon material. According to embodiments of this application, the carbon material includes: a zero-dimensional carbon material; and a two-dimensional carbon material, wherein the two-dimensional carbon material is located on the surface of the zero-dimensional carbon material, and the two-dimensional carbon material and the zero-dimensional carbon material are linked by chemical bonds. When this carbon material is used as a conductive agent in an electrode, the two-dimensional carbon material is located on the surface of the zero-dimensional carbon material, resulting in higher overlap efficiency of the edge two-dimensional carbon material, better conductivity, and superior liquid retention capacity, thereby improving the fast-charging performance of the electrode.

[0005] According to embodiments of this application, the average particle size D0 of the zero-dimensional carbon material is 20 nm to 60 nm; and / or, the average thickness L of the two-dimensional carbon material is 0.34 nm to 3.4 nm.

[0006] According to an embodiment of this application, the specific surface area of ​​the carbon material is 20 m². 2 / g~200 m 2 / g; and / or; and / or, the oil absorption value of the carbon material is 200mL / 100g to 420 mL / 100g.

[0007] A second aspect of this application provides a method for preparing the aforementioned carbon material. According to an embodiment of this application, the method includes: using a first carbon source as a gas source, performing a pyrolysis reaction at a first temperature to form a zero-dimensional carbon material; using a second carbon source as a gas source, performing chemical vapor deposition on the surface of the zero-dimensional carbon material at a second temperature to grow a two-dimensional carbon material in situ on the surface of the zero-dimensional carbon material, thereby obtaining the carbon material. This method can grow a two-dimensional carbon material in situ on the surface of a zero-dimensional carbon material, is simple and convenient to operate, and is easy to industrialize. Furthermore, when the prepared carbon material is used as a conductive agent in an electrode, the edge two-dimensional carbon material has higher overlap efficiency and better conductivity, which is beneficial for improving the fast-charging performance of the electrode.

[0008] According to embodiments of this application, the first carbon source and the second carbon source each independently include at least one of acetylene gas, ethylene gas, propylene gas, and methane gas.

[0009] According to an embodiment of this application, the first temperature is 1800 ℃~2800 ℃.

[0010] According to an embodiment of this application, the second temperature is 1700 ℃~2700 ℃.

[0011] In a third aspect, this application provides a conductive agent. According to embodiments of this application, the conductive agent comprises the carbon material described above or the carbon material prepared by the methods described above. When this conductive agent is used on an electrode, the edge-mounted two-dimensional carbon material exhibits higher overlap efficiency and better conductivity, thereby improving the fast-charging performance of the electrode.

[0012] According to embodiments of this application, the conductive agent further includes a second component, which includes at least one of superconducting carbon, acetylene black, conductive carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon fibers.

[0013] According to an embodiment of this application, the mass ratio of the carbon material to the second component is 0.5 to 10:1.

[0014] In a fourth aspect, this application provides an electrode. According to embodiments of this application, the electrode comprises the carbon material described above, the carbon material prepared by the method described above, or the conductive agent described above. This electrode exhibits high ion and electron transport performance, low resistance, good uniformity, and excellent liquid retention capacity, which is beneficial for improving the battery's initial efficiency, capacity retention rate, and rate performance.

[0015] According to an embodiment of this application, the electrode further includes an active material, wherein the mass ratio of the conductive agent to the active material is 0.02~3:96, preferably 0.5~3:96.

[0016] In a fifth aspect, this application provides a battery. According to embodiments of this application, the battery includes the carbon material described above, the carbon material prepared by the method described above, the conductive agent described above, or the electrode sheet described above. This battery possesses all the features and advantages of the carbon material, conductive agent, or electrode sheet described above, which will not be elaborated upon here.

[0017] In a sixth aspect, this application provides an electrical device. According to an embodiment of this application, the electrical device includes the carbon material described above, the carbon material prepared by the method described above, the conductive agent described above, the electrode sheet described above, or the battery described above. Attached Figure Description

[0018] Figure 1 This is a TEM image of the carbon material obtained in Preparation Example 1 of this application.

[0019] Figure 2 This is a TEM image of the carbon material binding sites obtained in Preparation Example 1 of this application. Detailed Implementation

[0020] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] In a first aspect, this application provides a carbon material. According to embodiments of this application, the carbon material includes: a zero-dimensional carbon material; and a two-dimensional carbon material, wherein the two-dimensional carbon material is located on the surface of the zero-dimensional carbon material, and the two-dimensional carbon material and the zero-dimensional carbon material are linked by chemical bonds. When this carbon material is used as a conductive agent in an electrode, the edge two-dimensional carbon material has a higher overlap efficiency and better conductivity; and after an SEI film is formed on the surface of the carbon material, the protruding two-dimensional carbon material can still maintain the electron network within the electrode, improving the charge-discharge performance and fast-charging performance of the battery during cycling.

[0022] In this article, zero-dimensional carbon materials refer to carbon materials that reach the nanoscale (i.e., 1 nm to 100 nm) in three mutually perpendicular spatial dimensions, with similar dimensions in the three dimensions and no identifiable extension direction in the microscopic dimension; two-dimensional carbon materials refer to carbon materials in which atoms extend regularly in a two-dimensional plane, and their thickness is usually on the nanometer scale.

[0023] According to embodiments of this application, the average particle size D0 of the zero-dimensional carbon material is 20 nm to 60 nm, specifically within the range of 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, or any two of these ranges. Therefore, when used as a conductive agent in electrodes, it can provide more contact points, reduce the electron transfer impedance of the electrode, and simultaneously save on the amount of conductive agent used, thereby improving the electrode's energy density and rate performance.

[0024] In this paper, the average particle size D0 of the zero-dimensional carbon material is the average particle size of the primary particles of the zero-dimensional carbon material.

[0025] According to embodiments of this application, the average thickness L of the two-dimensional carbon material is 0.34 nm to 3.4 nm, specifically within the range of 0.34, 0.5 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.4 nm, or any two of these ranges. Within this thickness range, the carbon material exhibits high in-plane conductivity, achieving a balance between electron and ion channels. When used as a conductive agent in electrodes, it can reduce the volume resistivity of the electrodes and improve capacity retention.

[0026] According to an embodiment of this application, the specific surface area of ​​the carbon material is 20 m². 2 / g~200 m 2 / g, specifically 20m 2 / g, 50m 2 / g、80m 2 / g, 100m 2 / g、120m 2 / g, 150m 2 / g、180m 2 / g、200m 2 / g or any two of the above ranges. Within the above range, when carbon materials are used as conductive agents in electrodes, they have sufficient surface area to form a 3D conductive network, reducing electrode resistance. At the same time, the electrolyte is fully wetted, the active ion diffusion coefficient is high, and there are few side reactions. Batteries using this electrode have a high initial efficiency.

[0027] According to embodiments of this application, the oil absorption value of the carbon material is 200 mL / 100g to 420 mL / 100g, specifically 200 mL / 100g, 220 mL / 100g, 250 mL / 100g, 280 mL / 100g, 300 mL / 100g, 320 mL / 100g, 350 mL / 100g, 380 mL / 100g, 400 mL / 100g, 420 mL / 100g, or any range between two of these. Therefore, a continuous 3D conductive network can be formed with a relatively small amount added, reducing electrode resistance. Simultaneously, the internal voids can "store liquid," increasing the electrode's liquid retention capacity, and there are fewer side reactions. This is beneficial for improving the initial efficiency, fast-charging performance, and capacity retention of batteries using carbon materials as conductive agents.

[0028] A second aspect of this application provides a method for preparing the aforementioned carbon material. According to an embodiment of this application, the method includes: using a first carbon source as a gas source, performing a pyrolysis reaction at a first temperature to form a zero-dimensional carbon material; using a second carbon source as a gas source, performing chemical vapor deposition on the surface of the zero-dimensional carbon material at a second temperature to grow a two-dimensional carbon material in situ on the surface of the zero-dimensional carbon material, thereby obtaining the carbon material. This method can grow a two-dimensional carbon material in situ on the surface of a zero-dimensional carbon material, is simple and convenient to operate, and is easy to industrialize. Furthermore, when the prepared carbon material is used as a conductive agent in an electrode, the edge two-dimensional carbon material has a higher overlap efficiency and better conductivity. Moreover, after an SEI is formed on the surface of the carbon material, the protruding two-dimensional carbon material can still maintain the electron network within the electrode, improving the charge-discharge performance and fast-charging performance of the battery during cycling.

[0029] In this article, pyrolysis reaction refers to the chemical process in which reactants undergo thermal decomposition at high temperatures in an oxygen-free or oxygen-deficient environment.

[0030] It should be noted that the first carbon source and the second carbon source can be the same or different; that is, the carbon source used in the pyrolysis reaction and chemical vapor deposition process can be the same or different, and can be flexibly selected according to actual needs.

[0031] According to embodiments of this application, the first carbon source and the second carbon source may independently include at least one of acetylene gas, ethylene gas, propylene gas, and methane gas. These carbon sources allow for the successful preparation of carbon materials and facilitate the rapid acquisition of carbon materials with good electrical conductivity at relatively low temperatures.

[0032] According to embodiments of this application, the first temperature is 1800℃~2800℃, specifically such as 1800℃, 1850℃, 1900℃, 1950℃, 2000℃, 2050℃, 2100℃, 2150℃, 2200℃, 2250℃, 2300℃, 2350℃, 2400℃, 2450℃, 2500℃, 2550℃, 2600℃, 2650℃, 2700℃, 2750℃, 2800℃, or any range between two of these. At the above temperatures, the carbon source can be efficiently converted into zero-dimensional carbon materials.

[0033] According to embodiments of this application, the second temperature is 1700~2700 °C, specifically 1700 °C, 1800 °C, 1900 °C, 2000 °C, 2100 °C, 2200 °C, 2300 °C, 2400 °C, 2500 °C, 2600 °C, 2700 °C, or any range between two of these. At the above temperatures, the carbon source can be efficiently converted into a two-dimensional carbon material.

[0034] In some embodiments, the carbon material is prepared as follows: using at least one of acetylene gas, ethylene gas, propylene gas, and methane gas as a carbon source, the carbon is introduced into a reactor and subjected to a pyrolysis reaction at 1800℃~2800℃. After the reaction is completed, acetylene gas, ethylene gas, propylene gas, methane gas, or a mixture thereof is added at a distance of 5 meters from the outlet. Chemical vapor deposition is then performed at a temperature of 1700℃~2700℃ to complete the secondary reaction growth, and the carbon material is subsequently collected.

[0035] In a third aspect, this application provides a conductive agent. According to embodiments of this application, the conductive agent comprises the carbon material described above or the carbon material prepared by the methods described above. When this conductive agent is used on an electrode, the edge-mounted two-dimensional carbon material exhibits higher overlap efficiency and better conductivity, and the carbon material also has superior liquid retention capacity, thereby improving the fast-charging performance of the electrode.

[0036] According to embodiments of this application, the conductive agent further includes a second component, which comprises at least one selected from superconducting carbon, acetylene black, conductive carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon fibers. Therefore, the use of different materials in combination can further enhance the conductivity of the conductive agent.

[0037] According to embodiments of this application, the mass ratio of the carbon material to the second component is 0.5 to 10:1, specifically such as 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, 10:1, or any range between two of these. Therefore, the carbon material and the second component can work synergistically to form a conductive network with better conductivity and a more stable structure, thereby improving the electrochemical performance of the electrode and the battery.

[0038] In a fourth aspect, this application provides an electrode. According to embodiments of this application, the electrode comprises the carbon material described above, the carbon material prepared by the method described above, or the conductive agent described above. This electrode exhibits good ion and electron transport performance, low resistance, good uniformity, and excellent liquid retention capacity, which is beneficial for improving the battery's initial efficiency, capacity retention rate, and rate performance.

[0039] According to embodiments of this application, the electrode further includes an active material, wherein the mass ratio of the conductive agent to the active material is 0.02 to 3:96, specifically 0.5 to 3:96, more specifically 0.02:96, 0.05:96, 0.1:96, 0.5:96, 1:96, 1.5:96, 2:96, 2.5:96, 3:96, or any range between two of these. Within the above ratio range, a better conductivity can be achieved with a lower amount of conductive agent, while simultaneously allowing the electrode to achieve both good conductivity and high capacity.

[0040] According to embodiments of this application, the electrode may include a current collector and a dressing layer disposed on at least one side of the current collector, wherein the dressing layer may include the aforementioned active material and a conductive agent.

[0041] According to embodiments of this application, the electrode can be either a positive electrode or a negative electrode. In some embodiments, the electrode is a negative electrode. Specifically, by using the aforementioned conductive agent, a uniform conductive network can be formed in the electrode, ensuring good bonding efficiency even when applied to a negative electrode with significant volume expansion, thereby improving the battery's rate performance, initial efficiency, and capacity retention.

[0042] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode dressing layer disposed on at least one side of the negative electrode current collector. The negative electrode dressing layer may include a negative electrode active material, a negative electrode binder, and the aforementioned conductive agent. Additives with specific functions and effects may also be added as needed, such as thickeners (e.g., sodium carboxymethyl cellulose CMC-Na), film-forming additives, flame retardants, high-temperature / low-temperature stabilizers, etc.

[0043] According to embodiments of this application, the negative electrode current collector can be a metal current collector or a composite current collector. For example, metal current collectors include, but are not limited to, copper foil current collectors; composite current collectors may include a polymer material base layer (such as a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.) and a metal layer (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) formed on at least one surface of the polymer material base layer.

[0044] In some embodiments, the main material of the negative electrode active material includes at least one selected from natural graphite, artificial graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microspheres, silicon-based materials, tin-based materials, and lithium titanate. In some specific examples, the main material of the negative electrode active material includes artificial graphite. Therefore, there is less reaction between the negative electrode and the electrolyte, which can effectively reduce battery heat generation and lower the risk of battery thermal runaway, while also exhibiting high capacity and low internal resistance.

[0045] In some embodiments, the negative electrode binder may include, but is not limited to, at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0046] In some embodiments, the negative electrode coating layer may include a negative electrode active material in a mass ratio of (90~98):(0.02~3):(1~5):(1~5), the aforementioned conductive agent, binder, and thickener. The negative electrode coating layer, having the above-mentioned components, exhibits less reaction between the negative electrode and the electrolyte, effectively reducing battery heat generation and lowering the risk of battery thermal runaway, while also possessing high capacity and low internal resistance.

[0047] In some embodiments, the positive electrode sheet may include a current collector and a positive electrode coating layer disposed on at least one side of the current collector. The positive electrode coating layer may include the main positive electrode active material, the aforementioned conductive agent, and the positive electrode binder, and may also include additives with specific functions and effects, such as lithium supplements, film-forming additives, flame retardants, high-temperature / low-temperature stabilizers, etc., as needed.

[0048] In some embodiments, the positive current collector can be a metal current collector or a composite current collector. For example, metal current collectors include, but are not limited to, aluminum foil current collectors; composite current collectors may include a polymer base layer (such as a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.) and a metal layer (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) formed on at least one surface of the polymer base film.

[0049] In some embodiments, the main cathode active material may include at least one of the following: layered structure cathode active materials (e.g., nickel-cobalt-manganese ternary cathode materials, nickel-cobalt-aluminum ternary cathode materials, lithium nickel oxide / sodium, lithium cobalt oxide / sodium, lithium manganese oxide / sodium, lithium-rich / sodium layered and rock salt phase layered materials), olivine-type phosphate active materials (e.g., lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, etc.), and spinel structure cathode active materials (e.g., spinel lithium manganese oxide, spinel lithium nickel manganese oxide, lithium-rich spinel lithium manganese oxide, and lithium nickel manganese oxide, etc.). It is understood that the aforementioned main cathode active material may further include doping elements and coating layers, etc.

[0050] In some embodiments, the positive electrode adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a terpolymer of PVDF-tetrafluoroethylene-propylene, a terpolymer of PVDF-hexafluoropropylene-tetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorinated acrylate resin. This allows the positive electrode dressing layer to adhere well to the positive electrode current collector, resulting in strong adhesion and reducing the likelihood of the positive electrode dressing detaching.

[0051] A fifth aspect of this application provides a battery. According to an embodiment of this application, the battery includes the carbon material described above, the carbon material prepared by the method described above, the conductive agent described above, or the electrode sheet described above. This battery possesses all the features and advantages of the carbon material, conductive agent, or electrode sheet described above, which will not be elaborated upon here.

[0052] According to embodiments of this application, the specific type of battery is not particularly limited; it can be a primary battery or a secondary battery. The shape of the battery can be cylindrical, prismatic, or any other shape. Based on its outer packaging, the battery can be a hard-shell battery, a soft-pack battery, etc. In other embodiments, the battery can be a lithium-ion battery, a sodium-ion battery, etc.

[0053] In some embodiments, the battery can be a single cell, a battery module, or a battery pack. The specific structure can be carried out with reference to conventional technology, and there are no particular limitations in this application.

[0054] Typically, a single battery cell includes a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode, negative electrode, and separator can be manufactured into a cell using winding or stacking processes. The cell and electrolyte can be housed in an outer package. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing active ions to pass through.

[0055] In some embodiments, the positive and negative electrodes can be the same as described above, and will not be repeated here.

[0056] In some embodiments, the separator may be a separator known in the art that can be used in batteries and is stable to the electrolyte used, such as a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene composite separator, etc.

[0057] According to embodiments of this application, the electrolyte may include electrolyte salts and solvents. Furthermore, additives with specific functions, such as film-forming additives, lithium replenishing agents, flame retardants, thermal stability additives, etc., may also be added to the electrolyte as needed.

[0058] In some embodiments, the electrolyte salt serves as the ion source and can be an electrolyte salt known in the art for use in battery electrolytes. Exemplarily, the electrolyte salt can be at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium nitrate (LiNO3), and lithium fluoride (LiF).

[0059] In some embodiments of this application, the solvent in the electrolyte may include one or more of carbonate solvents, ether solvents, and carboxylic acid ester solvents. As an example, the solvent in the electrolyte may include at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, and ethylene glycol dimethyl ether.

[0060] In some embodiments, the electrolyte further includes additives, including at least one selected from vinylene carbonate, fluoroethylene carbonate, propylene sulfite, and methane disulfonate. This facilitates the formation of an SEI film on the negative electrode surface, reduces side reactions, and improves the electrochemical performance of the battery.

[0061] In a sixth aspect, this application provides an electrical device. According to an embodiment of this application, the electrical device includes the carbon material described above, the carbon material prepared by the method described above, the conductive agent described above, the electrode sheet described above, or the battery described above.

[0062] According to embodiments of this application, the specific type of electrical device is not particularly limited and can be any device that uses a battery as a power source or energy storage unit. As examples, electrical devices include, but are not limited to, electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), mobile terminals (e.g., mobile phones, laptops, game consoles, wearable devices, etc.), drones, aerospace equipment, satellites, ships, energy storage systems, etc.

[0063] It is understood that, in addition to the battery mentioned above, the electrical device also includes other necessary structures and components, all of which can be made with reference to conventional technologies. For example, an electric vehicle may include a body, chassis, tires, navigation system, radar system, steering system, braking system, lubrication system, cooling system, driving system, etc., which will not be described in detail here.

[0064] The embodiments of this application are described in detail below.

[0065] Preparation Example 1 Acetylene gas was used as the carbon source and introduced into the reactor for pyrolysis at 2700 °C. After the reaction was completed, ethylene gas was added 5 meters from the outlet, and vapor deposition was performed at 2600 °C to complete the secondary reaction growth. Carbon material 1 was collected, and its TEM image is shown below. Figure 1 and Figure 2 ,from Figure 2 It can be seen that the lattice structure interface at the junction of the zero-dimensional carbon material and the two-dimensional carbon material is seamlessly connected, indicating that the two-dimensional carbon material is grown in situ on the surface of the zero-dimensional carbon material, and the two are connected by chemical bonds.

[0066] Preparation Example 2 Acetylene gas was used as a carbon source and introduced into the reactor for pyrolysis at 2800 °C. After the reaction was completed, a mixture of acetylene and methane gas was added 5 meters away from the outlet, and vapor deposition was performed at 2700 °C to complete the secondary reaction growth and collect carbon material 2.

[0067] Preparation Example 3 Acetylene gas was used as the carbon source and introduced into the reactor for pyrolysis at 2500 °C. After the reaction was completed, methane gas was added 5 meters away from the outlet, and vapor deposition was performed at 2450 °C to complete the secondary reaction growth and collect carbon material 3.

[0068] Preparation Example 4 Acetylene gas was used as the carbon source and introduced into the reactor. The first gas phase deposition treatment was carried out at 2750 °C. After the reaction was completed, methane gas was added 5 meters away from the outlet and the second gas phase deposition treatment was carried out at 2700 °C to complete the secondary reaction growth and collect carbon material 4.

[0069] Preparation Example 5 Acetylene gas was used as a carbon source and introduced into the reactor for pyrolysis at 2300 °C. After the reaction was completed, a mixture of acetylene and methane gas was added 5 meters away from the outlet, and vapor deposition was performed at 2200 °C to complete the secondary reaction growth and collect carbon material 5.

[0070] Preparation Example 6 Acetylene gas was used as the carbon source and introduced into the reactor for pyrolysis at 1800 °C. After the reaction was completed, methane gas was added 5 meters away from the outlet, and vapor deposition was performed at 2350 °C to complete the secondary reaction growth and collect carbon material 6.

[0071] Example 1: The positive electrode active material lithium iron phosphate (LiFePO4), conductive agent (conductive carbon black SP), and binder PVDF are mixed in a mass ratio of 97:1:2. The powder and NMP are then stirred in a homogenizer to form a positive electrode slurry, which is then uniformly coated onto aluminum foil.

[0072] The negative electrode active material, artificial graphite, carbon material 1, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:1:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0073] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 1:1:1 to prepare an electrolyte containing 1M LiPF6.

[0074] A 1.7Ah stacked battery was fabricated using a polypropylene separator.

[0075] Example 2: Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 1, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:0.02:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0076] Example 3: Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 1, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:3:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0077] Example 4: Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 2, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:1:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0078] Example 5: Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 3, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:1:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0079] Example 6: Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 4, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:1:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0080] Example 7: Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 5, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:1:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0081] Example 8: Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 6, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:1:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0082] Example 9: Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 1, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:0.01:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0083] Example 10: Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 1, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:4:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0084] Example 11 Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 1, conductive carbon black super-P, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:0.5:1:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0085] Example 12 Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 1, conductive carbon black super-P, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:1:0.1:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0086] Example 13 Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon material 1, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:0.5:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0087] Comparative Example 1: Same as Example 1, except that: The negative electrode active material, artificial graphite, carbon black, thickener (CMC), and binder (SBR) are mixed in a mass ratio of 96:1:2:0.5. The powder and deionized water are stirred into a negative electrode slurry using a homogenizer and then uniformly coated onto copper foil.

[0088] Comparative Example 2: Same as Example 1, except that: The negative electrode active materials, artificial graphite, carbon black, graphene, thickener (CMC), and binder (SBR), were mixed in a mass ratio of 96:0.5:0.5:2:0.5. The powder and deionized water were stirred together using a homogenizer to form a negative electrode slurry, which was then uniformly coated onto copper foil. The carbon black had a particle size of 40 nm, and the two-dimensional graphene had a thickness of 1.7 nm.

[0089] Performance testing: I. Performance Testing of Carbon Materials: 1. Separation of Carbon Material from Electrode: The negative electrode is placed in an HCl solution of a certain concentration. Stirring or ultrasonic treatment accelerates the dissolution process, removing the Cu foil, SBR, CMC, and SEI film from the electrode coating. The solution and insoluble components are then separated by filtration or centrifugation. The insoluble components are dried and ground into fine particles of a specific size. These particles are then mixed with an appropriate amount of solvent or dispersant and ultrasonically treated in an ultrasonic bath or using an ultrasonic probe to form a uniform suspension. During ultrasonic treatment, slight aggregation and dispersion occur due to the different characteristics of the negative electrode active material and the carbon material. After ultrasonication, the sample is centrifuged. Adjusting the centrifugation rate separates the carbon material and the negative electrode active material, allowing for separate property testing.

[0090] 2. Average particle size D0 of zero-dimensional carbon material: Based on the image obtained by TEM test, the maximum diameter of the zero-dimensional carbon material particle is taken as the particle size of the primary particle. 20 primary particles are randomly selected and their maximum particle size is measured, and the average value is taken.

[0091] 3. Average thickness L of two-dimensional carbon material: Based on the images obtained from TEM testing, 20 thicknesses of two-dimensional carbon materials were randomly selected, and their average value was taken.

[0092] 4. Specific surface area of ​​carbon materials: The specific operation shall be performed using a CANTA NOVA2000e specific surface area analyzer, and the specific operation shall be in accordance with the provisions of GB / T 19587.

[0093] 5. Oil absorption value of carbon materials: The S-500 oil absorption value tester is used for testing. The specific operation is in accordance with the provisions of GB / T 3780.2.

[0094] Table 1

[0095] II. Battery performance testing: 50% DC internal resistance (DCIR): The specific test method is as follows: (1) 25℃, 0.2C charge and discharge, cut-off voltage 2.0~3.8 V, calibrate battery capacity; (2) Charge at 0.2C to 50% SOC; (3) Set 2C charging for 30s, record the termination voltage and termination current of each process, and calculate DCIR. Specifically, DCIR = (V1-V2) / I, and the results are shown in Table 2. V1 is the voltage after charging for 30s, V2 is the voltage after the battery is adjusted to the target SOC and left to stand for 30 minutes, and I is the charging current.

[0096] Table 2

[0097] The data above shows that, compared with using zero-dimensional carbon materials alone as conductive agents and using a physical mixture of zero-dimensional and two-dimensional carbon materials as conductive agents, the carbon material with two-dimensional carbon materials grown in situ on the surface of zero-dimensional carbon materials has a significantly lower battery resistance and a significantly improved electrochemical performance.

[0098] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0099] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0100] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A carbon material, characterized in that, include: Zero-dimensional carbon materials; A two-dimensional carbon material, wherein the two-dimensional carbon material is located on the surface of the zero-dimensional carbon material, and the two-dimensional carbon material and the zero-dimensional carbon material are connected by chemical bonds.

2. The carbon material according to claim 1, characterized in that, The average particle size D0 of the zero-dimensional carbon material is 20 nm to 60 nm; and / or, The average thickness L of the two-dimensional carbon material is 0.34 nm to 3.4 nm.

3. The carbon material according to claim 1 or 2, characterized in that, The specific surface area of ​​the carbon material is 20 m². 2 / g~200 m 2 / g; and / or, The oil absorption value of the carbon material is 200 mL / 100g to 420 mL / 100g.

4. A method for preparing the carbon material according to any one of claims 1 to 3, characterized in that, include: Using the first carbon source as the gas source, a pyrolysis reaction is carried out at the first temperature to form a zero-dimensional carbon material. Using a second carbon source as a gas source, chemical vapor deposition is performed on the surface of the zero-dimensional carbon material at a second temperature to grow a two-dimensional carbon material in situ on the surface of the zero-dimensional carbon material, thereby obtaining the carbon material.

5. The method according to claim 4, characterized in that, At least one of the following conditions must be met: The first carbon source and the second carbon source each independently include at least one of acetylene gas, ethylene gas, propylene gas, and methane gas; The first temperature is 1800 ℃~2800 ℃; The second temperature is 1700 ℃~2700 ℃.

6. A conductive agent, characterized in that, The carbon material includes any one of claims 1 to 3 or the carbon material prepared by the method of claim 4 or 5.

7. The conductive agent according to claim 6, characterized in that, It also includes a second component, which includes at least one of superconducting carbon, acetylene black, conductive carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon fiber.

8. The conductive agent according to claim 7, characterized in that, The mass ratio of the carbon material to the second component is 0.5 to 10:

1.

9. An electrode sheet, characterized in that, The carbon material included in any one of claims 1 to 3, the carbon material prepared by the method of claim 4 or 5, or the conductive agent of any one of claims 6 to 8.

10. The electrode sheet according to claim 9, characterized in that, It also includes an active material, wherein the mass ratio of the conductive agent to the active material is 0.02 to 3:96, preferably 0.5 to 3:

96.

11. A battery, characterized in that, It includes the carbon material according to any one of claims 1 to 3, the carbon material prepared by the method according to claim 4 or 5, the conductive agent according to any one of claims 6 to 8, or the electrode according to claim 9 or 10.

12. An electrical appliance, characterized in that, The invention includes the carbon material according to any one of claims 1 to 3, the carbon material prepared by the method according to claim 4 or 5, the conductive agent according to any one of claims 6 to 8, the electrode according to claim 9 or 10, or the battery according to claim 11.

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