Carbon nanotube coated electrode material suitable for electrostatic spraying and preparation method thereof

Abstract

The invention relates to the technical field of battery materials, and particularly discloses a carbon nanotube coated electrode material suitable for electrostatic spraying and a preparation method thereof. The carbon nanotube coated electrode material suitable for electrostatic spraying comprises an inner core component which is an electrode material of a positive electrode, and an outer core component which is an electrode material of a negative electrode, the carbon nano tube is directly grown on the inner core component, and the carbon nano tube is connected with the inner core component through a contact. By adopting the method, the carbon nanotubes can be integrally grown on the electrode material, so that the conductivity of the material is improved, and the structural integrity of positive electrode material particles is also maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and particularly to an electrode material coated with carbon nanotubes suitable for electrostatic spraying and a preparation method thereof. Background Art

[0002] In the field of new energy materials, especially in the field of batteries, lithium-ion batteries are widely used in electric vehicles, portable electronic devices, energy storage systems and other fields due to their high energy density, long cycle life and environmental friendliness. However, the electrochemical performance of all batteries, especially lithium-ion batteries, largely depends on the performance of their positive electrode materials. Although lithium-ion batteries have advantages such as good safety performance, rich resources and low cost, their low electronic conductivity and ion conductivity limit their high-rate charge and discharge performance.

[0003] In order to improve the electrochemical performance of batteries, especially their high-current discharge performance, researchers have tried various modification methods. Among them, carbon nanotube (CNTs) coating is considered an effective modification means. Carbon nanotubes have a unique tubular structure, high conductivity and a large surface area, which can effectively improve the conductivity of materials, thereby improving the rate performance and cycle stability of batteries. Traditional coating methods have some limitations. These methods usually only bond carbon nanotubes to the electrode material by mechanical force, resulting in insufficiently tight and uniform contact between carbon nanotubes and the electrode material. This imperfect contact affects the electron transfer efficiency, thus limiting the improvement of battery performance. In addition, the mechanical bonding method may cause carbon nanotubes to fall off during the charge and discharge process of the battery, affecting the long-term stability of the battery.

[0004] Another problem is that it is difficult to precisely control the growth and distribution of carbon nanotubes by traditional coating methods. This may lead to uneven distribution of carbon nanotubes on the surface of the electrode material. Some areas may be over-coated, while other areas may be under-coated. This non-uniformity affects the overall performance of the electrode material and may cause local overheating or performance instability problems during the use of the battery.

[0005] In addition, existing coating technologies often require complex process flows and expensive equipment, which increases production costs and limits their promotion in large-scale commercial applications. At the same time, some coating methods may introduce additional impurities or damage the electrode material itself, which may have a negative impact on the performance of the battery.

[0006] In the prior art, Chinese Patent No. CN108054434A discloses a preparation method of a one-time electrospun flexible ultra-thin lithium-ion battery, including: (1) weighing graphene, carbon nanotubes and a solvent according to a ratio, and ultrasonically dispersing them to prepare a graphene / carbon nanotube colloidal solution; (2) spraying a graphene / carbon nanotube composite film negative electrode on a current collector by using a high-voltage electrostatic spraying device; (3) preparing a solid electrolyte material according to a ratio, and directly electrospinning a solid electrolyte thin film on the formed negative electrode by using a high-voltage electrospinning device; (4) electrospinning a positive electrode on the formed electrolyte thin film by using the prepared positive electrode material spinning solution; and finally attaching a metal foil current collector; thus obtaining the one-time electrospun flexible ultra-thin lithium-ion battery of the present invention.

[0007] During the preparation of the above lithium-ion battery, a graphene / carbon nanotube composite film negative electrode is sprayed on a current collector by using a high-voltage electrostatic spraying device. The graphene / carbon nanotubes are only physically mixed with the current collector and bonded together by mechanical force, and the electrochemical performance of the battery cannot be fully and efficiently exerted. Moreover, a graphene / carbon nanotube colloidal solution is used for liquid forming. Secondly, the graphene / carbon nanotube colloidal solution needs to be dispersed before spraying, and the existing dispersion equipment is difficult to achieve uniform dispersion, and the industrial application is difficult. The high-voltage electrospinning equipment has a large cost and it is difficult to achieve mass production. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide an electrode material coated with carbon nanotubes suitable for electrostatic spraying and a preparation method thereof, in which carbon nanotubes grow integrally on the electrode material, not only improving the conductivity of the material, but also maintaining the structural integrity of the positive electrode material particles.

[0009] The technical problem to be solved by the present invention is to provide an electrode material coated with carbon nanotubes suitable for electrostatic spraying and a preparation method thereof, with a simple and controllable process and suitable for industrial application.

[0010] To achieve the above technical effects, the present invention provides an electrode material coated with carbon nanotubes suitable for electrostatic spraying, including:

[0011] A core component, and the core component is an electrode material;

[0012] Carbon nanotubes, which directly grow on the core component, and the carbon nanotubes are connected to the core component through contact points;

[0013] The carbon nanotubes directly grow on the core component by the following method:

[0014] An active binder and a catalyst are sequentially added to the electrode material and ground, and then the growth of carbon nanotubes is carried out by a chemical vapor deposition device.

[0015] As an improvement of the above solution, the particle size of the core component is 0.1 μm to 20 μm, the diameter of the carbon nanotube is 2 nm to 20 nm, and the length of the carbon nanotube is 20 nm to 100 μm.

[0016] As an improvement of the above solution, the carbon nanotube and the core component are connected by a contact, and the diameter of the contact is 2 nm to 30 nm, forming a sea urchin-like structure.

[0017] As an improvement of the above solution, the core component is selected from one or more of the positive electrode materials of lithium ion batteries, sodium ion batteries, and sulfide batteries;

[0018] The positive electrode material of the lithium ion battery is selected from one or more of lithium cobaltate, lithium nickelate, lithium nickel cobalt aluminate, lithium manganate, lithium nickel manganate, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, and lithium vanadium phosphate oxide;

[0019] The positive electrode material of the sodium ion battery is selected from one or more of prussian blue compounds and prussian white compounds;

[0020] The positive electrode material of the sulfide battery is selected from one or more of lithium sulfide, iron sulfide, and cadmium sulfide.

[0021] As an improvement of the above solution, the active binder is selected from one or more of polyethylene glycol, polyvinyl alcohol, polypropylene, amide, polyethylene oxide, polyvinylpyrrolidone, gelatin, chitosan, and sodium carboxymethyl cellulose.

[0022] As an improvement of the above solution, the ratio of the added mass of the electrode material to the added mass of the active binder is 10:1 to 50:1.

[0023] As an improvement of the above solution, the catalyst is selected from one or more of metal catalysts, binary and multi-component alloy catalysts, and non-metal catalysts;

[0024] The particle size of the catalyst is nanoscale.

[0025] As an improvement of the above solution, the ratio of the added mass of the catalyst to the sum of the added masses of the electrode material and the active binder is 1:5 to 1:15.

[0026] Correspondingly, the present invention also discloses a preparation method of a carbon nanotube-coated electrode material suitable for electrostatic spraying, including:

[0027] Adding an active binder to the electrode material and mixing;

[0028] A catalyst is added to the electrode material mixed with the active binder, and the mixture is mixed and ground. Then, the obtained mixture is placed in a chemical vapor deposition device for the growth of carbon nanotubes to obtain a finished product.

[0029] As an improvement to the above solution, the step of placing the obtained mixture in a chemical vapor deposition device for the growth of carbon nanotubes includes:

[0030] Raise the temperature of the chemical vapor deposition device to 300 - 400 °C, introduce the first gas, and place the obtained mixture in the chemical vapor deposition device;

[0031] Raise the temperature of the chemical vapor deposition device to 600 - 760 °C, turn on the first gas and the second gas, carry out the growth of carbon nanotubes for 0.1 - 1 h, and take out after cooling.

[0032] As an improvement to the above solution, when the temperature of the chemical vapor deposition device is raised to 300 - 400 °C, the first gas introduced is nitrogen, and the flow rate of the first gas is set to 0.1 - 1.5 L / min.

[0033] As an improvement to the above solution, when the temperature of the chemical vapor deposition device is raised to 600 - 760 °C, the first gas introduced is nitrogen, and the flow rate of the first gas is set to 1.5 - 3 L / min; the second gas introduced is one or more of propylene, methane, acetylene, and ethylene, and the flow rate of the second gas is set to 0.5 - 2 L / min.

[0034] As an improvement to the above solution, a preparation method of an electrode material coated with carbon nanotubes suitable for electrostatic spraying includes:

[0035] Add an active binder to the electrode material and mix to obtain a first mixture;

[0036] Add deionized water to the first mixture and ball-mill to obtain a second mixture;

[0037] Bake the ball-milled second mixture;

[0038] Grind the baked second mixture;

[0039] Add a catalyst to the ground second mixture and ball-mill to obtain a third mixture;

[0040] Grind the third mixture;

[0041] Bake the ground third mixture;

[0042] Place the baked third mixture in a chemical vapor deposition device for the growth of carbon nanotubes to obtain a finished product.

[0043] As an improvement of the above solution, the mass ratio of the electrode material to the deionized water is 1:1 to 2:1.

[0044] Implementing the present invention has the following beneficial effects:

[0045] First, the present invention proposes a novel carbon nanotube-coated electrode material and its preparation method. This method combines the advantages of a polymer material having many surface active sites and being easily decomposed at high temperatures. By surface modification and its acting force, carbon nanotube catalysts are uniformly coated on the surface of the electrode material, and then carbon nanotubes are integrally grown through a chemical vapor deposition device. This not only improves the conductivity of the material but also maintains the structural integrity of the electrode material particles.

[0046] Second, for the novel carbon nanotube-coated electrode material of the present invention, the electrode material particles and the integrally grown carbon nanotubes form a sea urchin-like structure. This structure realizes the tight connection between the carbon nanotubes and the electrode material through a direct growth method, improves the electron transfer efficiency. At the same time, the formed sea urchin-like structure increases the specific surface area of the material, enabling conductive electron particles and conductive ion particles to be uniformly distributed on the electrode material, increasing the directional carrier path, improving the electrochemical performance of the battery, especially the high-current discharge performance, having excellent cycle stability, and also having good rate performance.

[0047] Third, the carbon nanotube-coated electrode material of the present invention is used for the preparation of a dry electrode, which can eliminate the use of solvents and can, to a certain extent, avoid the performance influence brought by the conductive agent and the binder during battery cycling.

[0048] Fourth, the preparation method provided by the present invention simplifies the production process, reduces the production cost, and is conducive to large-scale commercial applications. Description of the Drawings

[0049] Figure 1 is a flowchart of an embodiment of the preparation method of the carbon nanotube-coated electrode material suitable for electrostatic spraying according to the present invention;

[0050] Figure 2 is a flowchart of another embodiment of the preparation method of the carbon nanotube-coated electrode material suitable for electrostatic spraying according to the present invention;

[0051] Figure 3 is an electron micrograph of the catalyst adhering to the surface of the electrode material of the present invention;

[0052] Figure 4 is an electron micrograph of one perspective of the carbon nanotubes growing on the electrode material of the present invention;

[0053] Figure 5 is Figure 4 a partially enlarged view of the carbon nanotubes growing on the electrode material shown;

[0054] Figure 6 It is an electron microscope image of another perspective of the carbon nanotubes grown on the electrode material of the present invention;

[0055] Figure 7 is Figure 6 A partial enlarged view of the carbon nanotubes grown on the electrode material shown. Detailed implementation manners

[0056] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below.

[0057] In the field of new energy materials, especially in the field of batteries, lithium-ion batteries are widely used in electric vehicles, portable electronic devices, energy storage systems and other fields due to their high energy density, long cycle life and environmental friendliness. However, the electrochemical performance of all batteries, especially lithium-ion batteries, largely depends on the performance of their positive electrode materials. Although lithium-ion batteries have advantages such as good safety performance, rich resources and low cost, their low electronic conductivity and ion conductivity limit their high-rate charge and discharge performance. To improve the electrochemical performance of batteries, especially their high-current discharge performance, researchers have tried various modification methods, among which carbon nanotube coating is considered an effective modification means. Carbon nanotubes have a unique tubular structure, high conductivity and a large surface area, which can effectively improve the conductivity of materials, thereby improving the rate performance and cycle stability of batteries. However, the traditional coating is only bonded together by mechanical force and cannot fully and efficiently exert the electrochemical performance of the battery

[0058] Therefore, the present invention provides an electrode material with carbon nanotube coating suitable for electrostatic spraying and a preparation method thereof. This method combines the advantages of a large number of surface active sites of polymer materials and their easy decomposition at high temperatures. By surface modification and its acting force, the carbon nanotube catalyst is uniformly coated on the surface of the electrode material, and then carbon nanotubes are grown integrally through a fluidized bed, which not only improves the conductivity of the material but also maintains the structural integrity of the electrode material particles.

[0059] Specifically, the electrode material with carbon nanotube coating suitable for electrostatic spraying of the present invention includes:

[0060] The inner core component, and the inner core component is an electrode material, preferably a positive electrode material;

[0061] Carbon nanotubes, and the carbon nanotubes are directly grown on the inner core component, and the carbon nanotubes are connected to the inner core component through contacts;

[0062] The carbon nanotubes are directly grown on the inner core component by the following method:

[0063] Add the active binder and catalyst to the electrode material in sequence and grind them, and then grow carbon nanotubes through a chemical vapor deposition device.

[0064] In the field of batteries, the conductivity and electrochemical performance of the positive electrode material are the key factors affecting the overall performance of the battery. Due to the low conductivity of traditional positive electrode materials, the high-rate charge and discharge performance of the battery is limited. To overcome this problem, the method of coating with carbon nanotubes is adopted in the present invention. Carbon nanotubes have high conductivity and a large surface area, which can significantly improve the electron conductivity, thereby improving the rate performance and cycle stability of the battery. Specifically, the carbon nanotubes of the present invention are directly grown on the inner core component and form a sea urchin-like structure through contact connection. This structure not only increases the conductivity of the electrode material, but also improves its mechanical stability and maintains the structural integrity of the positive electrode material particles.

[0065] In the embodiment of the present invention, the active binder and catalyst are added to the electrode material in sequence and ground, and then carbon nanotubes are grown through a chemical vapor deposition device. Among them, the chemical vapor deposition device can be a fluidized bed CVD, which is suitable for large-scale production and can control the orientation and structure of carbon nanotubes.

[0066] In some embodiments, by controlling the particle size of the inner core component, the diameter and length of the carbon nanotubes, the uniformity of the carbon nanotubes coated on the surface of the electrode material can be improved, thereby improving the conductivity and electrochemical performance of the electrode material.

[0067] Preferably, the particle size of the inner core component is 0.1 μm to 20 μm, and exemplary values can be 0.1 μm, 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, but not limited thereto;

[0068] The diameter of the carbon nanotubes is 2 nm to 20 nm, and exemplary values can be 2 nm, 5 nm, 7 nm, 9 nm, 10 nm, 12 nm, 15 nm, 17 nm, 18 nm, 20 nm, but not limited thereto;

[0069] The length of the carbon nanotubes is 20 nm to 100 μm, and exemplary values can be 20 nm, 100 nm, 5000 nm, 1 μm, 5 μm, 10 μm, 50 μm, 80 μm, 100 μm, but not limited thereto.

[0070] By controlling the particle size of the inner core component, the diameter and length of the carbon nanotubes, it helps to optimize the distribution and arrangement of the carbon nanotubes, so that enough carbon nanotubes are uniformly coated on the surface of the electrode material, providing sufficient contact area and conduction paths, improving the conductivity and electrochemical performance of the electrode material, and enhancing the overall performance of the electrode material.

[0071] The carbon nanotubes are connected to the core components through contacts, and the diameter of the contacts is 2 nm to 30 nm. Exemplarily, it can be 2 nm, 5 nm, 7 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, 22 nm, 25 nm, 28 nm, 30 nm, but not limited thereto. The carbon nanotubes are connected to the core components through contacts to form a sea urchin-like structure. The novel carbon nanotube-coated electrode material of the present invention has an electrode material particle and an integrally grown carbon nanotube form a sea urchin-like structure. This structure realizes the tight connection between the carbon nanotubes and the electrode material through a direct growth method, increases the stability of the overall structure, improves the electron transport efficiency, and at the same time, the formed sea urchin-like structure increases the specific surface area of the material, enabling the electron-conducting particles and ion-conducting particles to be evenly distributed on the electrode material, increasing the directional carrier path, improving the electrochemical performance of the battery, especially the high-current discharge performance, having excellent cycle stability, and also having good rate performance.

[0072] In some embodiments, the core components are selected from one or more of the positive electrode materials of lithium-ion batteries, the positive electrode materials of sodium-ion batteries, and the positive electrode materials of sulfide batteries;

[0073] The positive electrode material of the lithium-ion battery is selected from one or more of lithium cobaltate, lithium nickelate, lithium nickel cobalt aluminate, lithium manganate, lithium nickel manganate, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, and lithium vanadate oxide;

[0074] The positive electrode material of the sodium-ion battery is selected from one or more of Prussian blue compounds and Prussian white compounds;

[0075] The positive electrode material of the sulfide battery is selected from one or more of lithium sulfide, iron sulfide, and cadmium sulfide;

[0076] The positive electrode material of the sulfide battery can also be selected with a core-shell structure. Among them, the core is generally a transition metal oxide, such as lithium cobaltate, lithium nickelate, lithium manganate, or nickel cobalt manganese ternary material, etc. The shell layer is a material with good conductivity and stable structure, such as carbon, lithium oxide, lithium titanate, aluminum oxide and other compounds.

[0077] In some embodiments, the active binder is selected from one or more of polyethylene glycol, polyvinyl alcohol, polypropylene, amide, polyethylene oxide, polyvinylpyrrolidone, gelatin, chitosan, and sodium carboxymethylcellulose. Preferably, the active binder is selected from one of polyethylene glycol, polyvinyl alcohol, polypropylene, amide, polyethylene oxide, polyvinylpyrrolidone, gelatin, chitosan, and sodium carboxymethylcellulose. The active binder can improve the binding performance and stability of the electrode material, so that the carbon nanotube catalyst is uniformly coated on the core components.

[0078] The mass ratio of the electrode material to the active binder is preferably 10:1 to 50:1, and exemplary values can be 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, but are not limited thereto.

[0079] In the embodiments of the present invention, the electrode material of the positive electrode and the active binder are uniformly mixed. Among them, the active binder can not only act as a surfactant but also act as a binder. The active binder modifies the electrode material of the positive electrode, laying a foundation for the subsequent uniform coating of the carbon nanotube catalyst on the surface of the positive electrode material.

[0080] In some embodiments, the catalyst is selected from one or more of metal catalysts, binary and multi-component alloy catalysts, and non-metal catalysts. In the powdery second mixture, adding the catalyst and performing ball milling again can make the carbon nanotube catalyst uniformly coat on the surface of the positive electrode material. Preferably, the particle size of the catalyst is nanoscale. The nanoscale catalyst can be more uniformly coated on the surface of the sieved positive electrode material.

[0081] It should be noted that the catalyst can specifically be any carbon nanotube catalyst. For example, the metal catalyst is selected from iron, nickel, cobalt, etc., the binary and multi-component alloy catalysts are selected from Fe-Co alloy, Fe-Ni alloy, etc., and the non-metal catalyst is selected from boron nitride, etc.

[0082] The ratio of the added mass of the catalyst to the sum of the added masses of the electrode material and the active binder is 1:5 to 1:15, and exemplary values can be 1:5, 1:6, 1:8, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, but are not limited thereto.

[0083] For the carbon nanotube-coated electrode material of the present invention, by sequentially adding an active binder and a catalyst to the electrode material and grinding, this method combines the advantages of a large number of surface active sites and easy decomposition at high temperature of the polymer material. The carbon nanotube catalyst is uniformly coated on the surface of the electrode material through surface modification and its acting force, and then carbon nanotubes are integrally grown through a chemical vapor deposition device. This not only improves the conductivity of the material but also maintains the structural integrity of the electrode material particles.

[0084] The carbon nanotube-coated electrode material of the present invention has an electrode material particle and integrally grown carbon nanotubes form a sea urchin-like structure. This structure realizes the tight connection between the carbon nanotubes and the electrode material through a direct growth method, improves the electron transport efficiency, and at the same time, the formed sea urchin-like structure increases the specific surface area of the material, enabling the electron-conducting particles and ion-conducting particles to be evenly distributed on the electrode material, increasing the directional carrier path, improving the electrochemical performance of the battery, especially the high-current discharge performance, having excellent cycle stability, and also having good rate performance.

[0085] The carbon nanotube-coated electrode material of the present invention is used for the preparation of dry electrodes, which can eliminate the use of solvents, can avoid the performance influence brought by the conductive agent and binder during battery cycling to a certain extent, and has a high electrode solid content, can improve the energy density, and significantly improve the cycle performance stability of the battery.

[0086] Correspondingly, as Figure 1 shown, the present invention also discloses an embodiment of a preparation method of a carbon nanotube-coated electrode material suitable for electrostatic spraying, including:

[0087] S101. Add an active binder to the electrode material and mix;

[0088] In some embodiments, the adding an active binder to the electrode material and mixing includes:

[0089] Add an active binder to the electrode material and mix to obtain a first mixture;

[0090] Add deionized water to the first mixture, and obtain a second mixture after ball milling;

[0091] Bake the ball-milled second mixture.

[0092] Preferably, add deionized water to the first mixture, ball mill and mix, the rotation speed of the ball milling is 100-300 rpm, and the ball milling time is 0.5-2 h.

[0093] Preferably, bake the ball-milled second mixture, the baking temperature is 45°C-70°C, and the baking time is 2-12 h.

[0094] More preferably, the temperature of the baked second mixture is 45°C-70°C, and the humidity is 50%-75%. By controlling the temperature and humidity of the baked second mixture, the catalyst can be more evenly and stably coated on the surface of the electrode material.

[0095] In this step, the electrode material and the active binder are mixed evenly. Herein, the active binder can not only act as a surfactant but also as a binder. The active binder modifies the electrode material, laying a foundation for the subsequent uniform coating of the carbon nanotube catalyst on the surface of the electrode material.

[0096] S102. Add a catalyst to the electrode material mixed with the active binder, mix and grind, and then put the obtained mixture into a chemical vapor deposition device for the growth of carbon nanotubes to obtain the finished product.

[0097] In some embodiments, add a catalyst to the electrode material mixed with the active binder, mix and grind. During the grinding process, control the humidity of the mixture, and the humidity is preferably between 30% and 45%, more preferably between 30% and 40%. By controlling the humidity of the mixture during the grinding process, it is beneficial for the catalyst to adhere to the electrode material.

[0098] It should be noted that the grinding step can be ordinary grinding or ball milling. Ball milling can not only achieve efficient and uniform mixing of the active binder, electrode material, catalyst, etc., but also promote solid-phase reactions and improve battery performance.

[0099] In some embodiments, the step of putting the obtained mixture into a chemical vapor deposition device for the growth of carbon nanotubes includes:

[0100] Raise the temperature of the chemical vapor deposition device to 300 - 400 °C, introduce the first gas, and put the obtained mixture into the chemical vapor deposition device;

[0101] Raise the temperature of the chemical vapor deposition device to 600 - 760 °C, turn on the first gas and the second gas, carry out the growth of carbon nanotubes for 0.1 - 1 h, and take out after cooling.

[0102] Wherein, when the temperature of the chemical vapor deposition device is raised to 300 - 400 °C, the first gas introduced is nitrogen, and the flow rate of the first gas is set to 0.1 - 1.5 L / min.

[0103] When the temperature of the chemical vapor deposition device is raised to 600 - 760 °C, the first gas introduced is nitrogen, and the flow rate of the first gas is set to 1.5 - 3 L / min; the second gas introduced is one or more of propylene, methane, acetylene, and ethylene, and the flow rate of the second gas is set to 0.5 - 2 L / min.

[0104] As a more preferred embodiment, the step of putting the obtained mixture into a chemical vapor deposition device for the growth of carbon nanotubes includes:

[0105] Heat up the temperature of the chemical vapor deposition equipment to 300 - 400 °C, set the flow rate of nitrogen gas to 0.1 - 1.5 L / min, and put the obtained mixture into the chemical vapor deposition equipment;

[0106] Heat up the temperature of the chemical vapor deposition equipment to 600 - 760 °C, turn on the propylene gas, and set the flow rate of the propylene gas to 0.5 - 2 L / min ， Set the flow rate of nitrogen gas to 1.5 - 3 L / min, grow carbon nanotubes for 0.1 - 1 h, and take them out after cooling.

[0107] It should be noted that the chemical vapor deposition equipment can be CVD, but not limited to this.

[0108] This step solves the problem of effectively controlling the growth conditions of carbon nanotubes in the process of preparing the carbon nanotube-coated electrode material. By optimizing the staged heating and gas flow rate of the chemical vapor deposition equipment, the carbon nanotubes grow under suitable conditions, ensuring the uniform growth and stability of the carbon nanotubes, thereby improving the performance and consistency of the electrode material.

[0109] Correspondingly, as Figure 2 shown, the present invention also discloses another embodiment of a preparation method of a carbon nanotube-coated electrode material suitable for electrostatic spraying, including:

[0110] S101. Select the positive electrode material as the core component, add an active binder to the positive electrode material and mix to obtain a first mixture;

[0111] In some embodiments, the active binder is selected from one or more of polyethylene glycol, polyvinyl alcohol, polypropylene, amide, polyethylene oxide, polyvinylpyrrolidone, gelatin, chitosan, sodium carboxymethyl cellulose. Preferably, the active binder is selected from one of polyethylene glycol, polyvinyl alcohol, polypropylene, amide, polyethylene oxide, polyvinylpyrrolidone, gelatin, chitosan, sodium carboxymethyl cellulose. The active binder can improve the binding performance and stability of the electrode material, so that the carbon nanotube catalyst is uniformly coated on the core component.

[0112] In some embodiments, the core component is selected from one or more of the positive electrode materials of lithium-ion batteries, sodium-ion batteries, and sulfide batteries;

[0113] The positive electrode material of the lithium-ion battery is selected from one or more of lithium cobaltate, lithium nickelate, lithium nickel cobalt aluminate, lithium manganate, lithium nickel manganate, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, and lithium vanadium phosphate oxide;

[0114] The positive electrode material of the sodium-ion battery is selected from one or more of Prussian blue compounds and Prussian white compounds;

[0115] The positive electrode material of the sulfide battery is selected from one or more of lithium sulfide, iron sulfide, and cadmium sulfide;

[0116] The positive electrode material of the sulfide battery can also be selected with a core-shell structure. Among them, the core is generally a transition metal oxide, such as lithium cobaltate, lithium nickelate, lithium manganate, or nickel cobalt manganese ternary material, etc. The shell layer: The shell layer is a material with good conductivity and stable structure, such as compounds like carbon, lithium oxide, lithium titanate, and aluminum oxide.

[0117] The mass ratio of the electrode material to the active binder is preferably 10:1 to 50:1, and exemplary values can be 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, but not limited thereto.

[0118] S102. Add deionized water to the first mixture, place it in a ball mill for ball milling to obtain a second mixture;

[0119] In some embodiments, the mass ratio of the electrode material to the deionized water is preferably 1:1 to 2:1, and exemplary values can be 1:1, 1.2:1, 1.3:1, 1.5:1, 1.4:1, 1.8:1, 2:1, but not limited thereto.

[0120] In some embodiments, the rotation speed of the ball milling is preferably 100 - 300 rpm, and the ball milling time is preferably 0.5 - 2 h.

[0121] In this step, the electrode material of the positive electrode and the active binder are mixed evenly. Among them, the active binder can not only act as a surfactant but also as a binder. The active binder modifies the electrode material of the positive electrode, laying a foundation for the subsequent uniform coating of the carbon nanotube catalyst on the surface of the positive electrode material.

[0122] S103. Bake the ball-milled second mixture;

[0123] In some embodiments, the baking temperature is 45°C to 70°C, and the baking time is 2 - 12 h, for removing the moisture in the second mixture.

[0124] S104. Grind the baked second mixture;

[0125] In some embodiments, the baked second mixture is ground into powder, preferably passing through a 50 - 300 mesh sieve.

[0126] S105. Add a catalyst to the ground second mixture and perform ball milling to obtain a third mixture;

[0127] In some embodiments, the catalyst is selected from one or more of metal catalysts, binary and multi-component alloy catalysts, and non-metal catalysts. Adding the catalyst to the powdery second mixture and then performing ball milling again can uniformly coat the carbon nanotube catalyst on the surface of the cathode material. Preferably, the particle size of the catalyst is nanoscale. The nanoscale catalyst can be more uniformly coated on the surface of the sieved cathode material.

[0128] It should be noted that the catalyst can specifically be any carbon nanotube catalyst. For example, the metal catalyst can be iron, nickel, cobalt, etc., the binary and multi-component alloy catalysts can be Fe-Co alloy, Fe-Ni alloy, etc., and the non-metal catalyst can be boron nitride, etc.

[0129] In some embodiments, the rotation speed of the ball milling is preferably 100 - 300 rpm, and the ball milling time is preferably 0.5 - 2 h.

[0130] In some embodiments, the ratio of the added mass of the catalyst to the sum of the added masses of the electrode material and the active binder is 1:5 - 1:15. Exemplarily, it can be 1:5, 1:6, 1:8, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, but not limited thereto. The added mass of the catalyst can be adjusted according to the selected materials of the electrode material and the active binder, as well as the performance requirements of the motor material.

[0131] S106. Grind the third mixture;

[0132] In some embodiments, the third mixture obtained after ball milling is ground again into powder, and preferably sieved through a 50 - 300 mesh sieve.

[0133] S107. Bake the ground third mixture;

[0134] In some embodiments, the baking temperature of the third mixture is 45°C - 70°C, and the baking time is 5 - 120 min, for removing the moisture of the third mixture.

[0135] S108. Place the baked third mixture into a chemical vapor deposition device for the growth of carbon nanotubes to obtain the finished product.

[0136] In some embodiments, in step S108, the operation of placing the baked third mixture into a chemical vapor deposition device for the growth of carbon nanotubes to obtain the finished product includes:

[0137] Raise the temperature of the chemical vapor deposition device to 300 - 400°C, introduce the first gas, and place the baked third mixture into the chemical vapor deposition device;

[0138] Heat up the temperature of the chemical vapor deposition equipment to 600 - 760 °C, turn on the first gas and the second gas, grow carbon nanotubes for 0.1 - 1 h, and take out the product after cooling.

[0139] Among them, when the temperature of the chemical vapor deposition equipment is heated up to 300 - 400 °C, the first gas introduced is nitrogen, and the flow rate of the first gas is set to 0.1 - 1.5 L / min;

[0140] When the temperature of the chemical vapor deposition equipment is heated up to 600 - 760 °C, the first gas introduced is nitrogen, and the flow rate of the first gas is set to 1.5 - 3 L / min; the second gas introduced is one or more of propylene, methane, acetylene, and ethylene, and the flow rate of the second gas is set to 0.5 - 2 L / min.

[0141] As a more preferred embodiment, in step S108, the step of putting the baked third mixture into the chemical vapor deposition equipment to grow carbon nanotubes to obtain the finished product includes:

[0142] Heat up the temperature of the chemical vapor deposition equipment to 300 - 400 °C, set the flow rate of nitrogen to 0.1 - 1.5 L / min, and put the baked third mixture into the chemical vapor deposition equipment;

[0143] Heat up the temperature of the chemical vapor deposition equipment to 600 - 760 °C, turn on the propylene gas, and the flow rate of the propylene gas is set to 0.5 - 2 L / min ， Set the flow rate of nitrogen to 1.5 - 3 L / min, grow carbon nanotubes for 0.1 - 1 h, and take out the product after cooling.

[0144] This step solves the problem of effectively controlling the growth conditions of carbon nanotubes in the process of preparing the carbon nanotube-coated electrode material. By optimizing the staged heating and gas flow rate of the chemical vapor deposition equipment, the carbon nanotubes grow under suitable conditions, ensuring the uniform growth and stability of the carbon nanotubes, thereby improving the performance and consistency of the electrode material.

[0145] The following further elaborates the present invention with specific embodiments

[0146] Example 1

[0147] (1) Mix 50 g of lithium iron phosphate and 2 g of polyethylene glycol to obtain the first mixture;

[0148] (2) Add 50 g of deionized water to the first mixture, place it in a ball mill for ball milling, the rotation speed of the ball mill is 100 rpm, and the ball milling time is 0.5 h to obtain the second mixture;

[0149] (3) Bake the second mixture after ball milling at a temperature of 50 °C for 5 h;

[0150] (4) Add 2 g of catalyst to 18 g of the ground second mixture and perform ball milling. Spray water mist during the ball milling process, control the humidity of the mixture to 30%, the rotation speed of the ball milling to 100 rpm, and the ball milling time to 1 h to obtain the third mixture;

[0151] (5) Heat up the temperature of the chemical vapor deposition equipment to 300 °C, set the flow rate of nitrogen to 0.5 ml / min, and place the baked third mixture into the chemical vapor deposition equipment; heat up the temperature of the chemical vapor deposition equipment to 600 °C, turn on the propylene gas, and set the flow rate of the propylene gas to 0.5 ml / min ， Set the flow rate of nitrogen to 1.5 ml / min, grow carbon nanotubes for 0.5 h, and take out after cooling to obtain the electrode material grown with carbon nanotubes.

[0152] Example 2

[0153] (1) Mix 100 g of lithium manganese phosphate and 3 g of polyethylene oxide to obtain the first mixture;

[0154] (2) Add 100 g of deionized water to the first mixture, place it in a ball mill for ball milling at a rotation speed of 200 rpm for 2 h to obtain the second mixture;

[0155] (3) Bake the second mixture after ball milling at a temperature of 70 °C for 8 h;

[0156] (4) Add 2 g of catalyst to 25 g of the ground second mixture and perform ball milling. Spray water mist during the ball milling process, control the humidity of the mixture to 40%, the rotation speed of the ball milling to 200 rpm, and the ball milling time to 2 h to obtain the third mixture;

[0157] (5) Heat up the temperature of the chemical vapor deposition equipment to 400 °C, set the flow rate of nitrogen to 1.5 ml / min, and place the baked third mixture into the chemical vapor deposition equipment; heat up the temperature of the chemical vapor deposition equipment to 760 °C, turn on the propylene gas, and set the flow rate of the propylene gas to 2 ml / min ， Set the flow rate of nitrogen to 3 ml / min, grow carbon nanotubes for 3 h, and take out after cooling to obtain the electrode material grown with carbon nanotubes.

[0158] Example 3

[0159] (1) Mix 50 g of lithium iron phosphate and 2 g of polyethylene glycol to obtain the first mixture;

[0160] (2) Add 50 g of deionized water to the first mixture, place it in a ball mill for ball milling, the rotation speed of the ball milling is 100 rpm, and the ball milling time is 0.5 h to obtain a second mixture;

[0161] (3) Bake the ball-milled second mixture, the baking temperature is 50 °C, and the baking time is 5 h;

[0162] (4) Grind the baked second mixture and pass it through a 100-mesh sieve;

[0163] (5) Add 2 g of catalyst to 18 g of the ground second mixture and perform ball milling. Spray water mist during the ball milling process, control the humidity of the mixture to be 30%, the rotation speed of the ball milling is 100 rpm, and the ball milling time is 1 h to obtain a third mixture;

[0164] (6) Grind the third mixture and pass it through a 100-mesh sieve;

[0165] (7) Bake the ground third mixture, the baking temperature is 60 °C, and the baking time is 20 min;

[0166] (8) Raise the temperature of the chemical vapor deposition equipment to 300 °C, set the flow rate of nitrogen to 0.5 L / min, and place the baked third mixture into the chemical vapor deposition equipment; raise the temperature of the chemical vapor deposition equipment to 600 °C, turn on the propylene gas, and set the flow rate of the propylene gas to 0.5 L / min ， Set the flow rate of nitrogen to 1.5 L / min, carry out the growth of carbon nanotubes for 0.5 h, take it out after cooling to obtain an electrode material grown with carbon nanotubes.

[0167] Example 4

[0168] (1) Mix 30 g of lithium cobaltate and 2 g of polyethylene oxide to obtain a first mixture;

[0169] (2) Add 35 g of deionized water to the first mixture, place it in a ball mill for ball milling, the rotation speed of the ball milling is 200 rpm, and the ball milling time is 1 h to obtain a second mixture;

[0170] (3) Bake the ball-milled second mixture, the baking temperature is 55 °C, and the baking time is 4 h;

[0171] (4) Grind the baked second mixture and pass it through a 200-mesh sieve;

[0172] (5) Add 2 g of catalyst to 20 g of the ground second mixture and perform ball milling. During ball milling, spray water mist to control the humidity of the mixture to 35%, the rotation speed of ball milling is 200 rpm, and the ball milling time is 1 h to obtain the third mixture;

[0173] (6) Grind the third mixture and pass it through a 200-mesh sieve;

[0174] (7) Bake the ground third mixture at a temperature of 60 °C for 50 min;

[0175] (8) Raise the temperature of the chemical vapor deposition equipment to 350 °C, set the flow rate of nitrogen to 0.5 L / min, and place the baked third mixture into the chemical vapor deposition equipment; raise the temperature of the chemical vapor deposition equipment to 650 °C, turn on the methane gas, and set the flow rate of methane gas to 1 L / min ， Set the flow rate of nitrogen to 2 L / min, grow carbon nanotubes for 1 h, and take out after cooling to obtain the electrode material grown with carbon nanotubes.

[0176] Example 5

[0177] (1) Mix 50 g of lithium iron phosphate and 1.5 g of chitosan to obtain the first mixture;

[0178] (2) Add 50 g of deionized water to the first mixture, place it in a ball mill for ball milling, the rotation speed of ball milling is 300 rpm, and the ball milling time is 1 h to obtain the second mixture;

[0179] (3) Bake the ball-milled second mixture at a temperature of 50 °C for 6 h;

[0180] (4) Grind the baked second mixture and pass it through a 200-mesh sieve;

[0181] (5) Add 3 g of catalyst to 20 g of the ground second mixture and perform ball milling. During ball milling, spray water mist to control the humidity of the mixture to 40%, the rotation speed of ball milling is 300 rpm, and the ball milling time is preferably 1 h to obtain the third mixture;

[0182] (6) Grind the third mixture and pass it through a 200-mesh sieve;

[0183] (7) Bake the ground third mixture at a temperature of 60 °C for 100 min;

[0184] (8) Heat up the temperature of the chemical vapor deposition equipment to 380 °C, set the flow rate of nitrogen gas to 1.2 L / min, and put the baked third mixture into the chemical vapor deposition equipment; heat up the temperature of the chemical vapor deposition equipment to 660 °C, turn on the propylene gas, and set the flow rate of the propylene gas to 1.5 L / min ， Set the flow rate of nitrogen gas to 2.5 L / min, grow carbon nanotubes for 2 h, take them out after cooling, and obtain the electrode material grown with carbon nanotubes.

[0185] Example 6

[0186] (1) Mix 100 g of lithium manganese phosphate and 3 g of polyethylene oxide to obtain the first mixture;

[0187] (2) Add 100 g of deionized water to the first mixture, place it in a ball mill for ball milling, the rotation speed of the ball mill is 200 rpm, and the ball milling time is 2 h to obtain the second mixture;

[0188] (3) Bake the ball-milled second mixture, the baking temperature is 70 °C, and the baking time is 8 h;

[0189] (4) Grind the baked second mixture and pass it through a 300-mesh sieve;

[0190] (5) Add 2 g of catalyst to 25 g of the ground second mixture and conduct ball milling. Spray water mist during the ball milling process, control the humidity of the mixture to 38%, the rotation speed of the ball mill is 200 rpm, and the ball milling time is 2 h to obtain the third mixture;

[0191] (6) Grind the third mixture and pass it through a 300-mesh sieve;

[0192] (7) Bake the ground third mixture, the baking temperature is 70 °C, and the baking time is 120 min;

[0193] (8) Heat up the temperature of the chemical vapor deposition equipment to 400 °C, set the flow rate of nitrogen gas to 1.5 L / min, and put the baked third mixture into the chemical vapor deposition equipment; heat up the temperature of the chemical vapor deposition equipment to 760 °C, turn on the propylene gas, and set the flow rate of the propylene gas to 2 L / min ， Set the flow rate of nitrogen gas to 3 L / min, grow carbon nanotubes for 3 h, take them out after cooling, and obtain the electrode material grown with carbon nanotubes.

[0194] Perform electron microscopy observation on the electrostatically sprayed carbon nanotube-coated electrode materials obtained in Examples 1-6. In Examples 1-6, the carbon nanotube catalyst can be uniformly coated on the surface of the positive electrode material. The coating rates of the carbon nanotube catalysts in each example are shown in Table 1:

[0195]

[0196] Moreover, the electrode material coated with carbon nanotubes by electrostatic spraying obtained in Example 3 was observed by electron microscopy. After the fifth step of treatment in Example 3, the carbon nanotube catalyst could be uniformly coated on the surface of the positive electrode material. The electron micrograph is as shown in Figure 3 . As can be seen from Figure 3 , the carbon nanotube catalyst was uniformly coated on the surface of the positive electrode material, and the coating rate reached more than 85%.

[0197] After the eighth step of treatment, the electron micrograph of the electrode material is as shown in Figure 4 -7. Figure 4 And Figure 5 show the growth of carbon nanotubes on the electrode material of the present invention from one perspective; Figure 6 and Figure 7 show the growth of carbon nanotubes on the electrode material of the present invention from another perspective. As can be seen from Figure 4 -7, carbon nanotubes grow integrally on the electrode material. The carbon nanotubes grow upward along the catalyst and wrap the positive electrode material, providing more conductive sites for the positive electrode material.

[0198] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A carbon nanotube-coated electrode material suitable for electrostatic spraying, characterized in that: include: A core component, wherein the core component is an electrode material; Carbon nanotubes, wherein the carbon nanotubes are directly grown on the core component, and the carbon nanotubes are connected to the core component via contacts; The carbon nanotubes are grown directly on the core component by the following method: Active binders and catalysts are sequentially added to the electrode material and ground, and then carbon nanotubes are grown through chemical vapor deposition equipment.

2. The carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 1, characterized in that: The particle size of the core component is 0.1 μm to 20 μm, the diameter of the carbon nanotube is 2 nm to 20 nm, and the length of the carbon nanotube is 20 nm to 100 μm.

3. The carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 1 or 2, characterized in that: The carbon nanotubes are connected to the core components via contacts, the diameter of the contacts is 2nm to 30nm, forming a sea urchin-like structure.

4. The carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 1 or 2, characterized in that: The core component is selected from one or more of the positive electrode materials of lithium ion batteries, the positive electrode materials of sodium ion batteries, and the positive electrode materials of sulfide batteries; The positive electrode material of the lithium-ion battery is selected from one or more of lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, and lithium vanadium phosphate; The positive electrode material of the sodium ion battery is selected from one or more of a Prussian blue compound and a Prussian white compound; The positive electrode material of the sulfide battery is selected from one or more of lithium sulfide, iron sulfide and cadmium sulfide.

5. The carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 1 or 2, characterized in that: The active binder is selected from one or more of polyethylene glycol, polyvinyl alcohol, polypropylene, amide, polyethylene oxide, polyvinyl pyrrolidone, gelatin, chitosan, and sodium carboxymethyl cellulose.

6. The carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 5, characterized in that: The ratio of the added mass of the electrode material to the added mass of the active binder is 10:1 to 50:

1.

7. The carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 1 or 2, characterized in that: The catalyst is selected from one or more of metal catalysts, binary and multi-element alloy catalysts, and non-metal catalysts; The particle size of the catalyst is nanometer scale.

8. The carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 7, characterized in that: The ratio of the added mass of the catalyst to the sum of the added mass of the electrode material and the active binder is 1:5 to 1:

15.

9. A method for preparing a carbon nanotube-coated electrode material suitable for electrostatic spraying as claimed in any one of claims 1 to 8, characterized in that: include: Adding active binder to electrode material and mixing; A catalyst is added to an electrode material mixed with an active binder, mixed and ground, and then the resulting mixture is placed in a chemical vapor deposition device to grow carbon nanotubes to obtain a finished product.

10. The method for preparing a carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 9, characterized in that: The step of placing the obtained mixture into a chemical vapor deposition device to grow carbon nanotubes comprises: Raising the temperature of the chemical vapor deposition equipment to 300-400° C., introducing the first gas, and placing the resulting mixture into the chemical vapor deposition equipment; The temperature of the chemical vapor deposition equipment is raised to 600-760°C, the first gas and the second gas are turned on, and the carbon nanotubes are grown for 0.1-1h, and then taken out after cooling.

11. The method for preparing a carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 9, characterized in that: When the temperature of the chemical vapor deposition equipment is raised to 300-400° C., the first gas introduced is nitrogen, and the flow rate of the first gas is set to 0.1-1.5 L / min.

12. The method for preparing a carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 11, characterized in that: When the temperature of the chemical vapor deposition equipment rises to 600-760°C, the first gas introduced is nitrogen, and the flow rate of the first gas is set to 1.5-3L / min; the second gas introduced is one or more of propylene, methane, acetylene, and ethylene, and the flow rate of the second gas is set to 0.5-2L / min.

13. The method for preparing a carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 9, characterized in that: include: Adding an active binder to the electrode material and mixing to obtain a first mixture; Adding deionized water to the first mixture and ball milling to obtain a second mixture; roasting the ball-milled second mixture; grinding the roasted second mixture; adding a catalyst to the ground second mixture and performing ball milling to obtain a third mixture; grinding the third mixture; roasting the ground third mixture; The baked third mixture is placed in a chemical vapor deposition device to grow carbon nanotubes to obtain a finished product.

14. The method for preparing a carbon nanotube-coated electrode material suitable for electrostatic spraying according to claim 13, characterized in that: The mass ratio of the electrode material to the deionized water is 1:1 to 2:1.

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