Nanocoated super-fast charging material and preparation method thereof

Abstract

The application relates to the technical field of energy storage fast charging materials, in particular to a preparation method of a nano-coated super fast charging material, which comprises the following steps: selecting raw materials to perform grinding treatment, shaping the materials after grinding to screen out particles with a specific particle size, loading the shaped particles into a high-temperature graphitization furnace, introducing argon as a protective gas, keeping the temperature at a set temperature, and then naturally cooling to room temperature to obtain a graphitized base material; the nano-coating agent is prepared by using a detonation method, the technical bottleneck of particle size out of control in the traditional ball milling method is effectively broken, the particle size of the coating agent can be accurately controlled, the charge transfer impedance in the material is significantly reduced, the core guarantee for the excellent super fast charging performance of the material is provided, and the defects of insufficient fast charging capacity caused by the particle size of the coating agent in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of energy storage fast charging materials technology, specifically to a nano-coated super fast charging material and its preparation method. Background Technology

[0002] With the rapid development of energy storage and power batteries, the market demand for super-fast charging materials is becoming increasingly urgent. Such materials need to simultaneously meet the core requirements of fast charging capability, long-term cycle stability, high energy efficiency, and low-cost industrialization.

[0003] However, existing super-fast charging material preparation technologies still face numerous technical bottlenecks, making it difficult to achieve the synergistic improvement of the aforementioned performance. Traditional coating agents are mostly prepared using ordinary ball milling, a method that cannot precisely control the particle size of the coating agent, easily leading to excessively large and unevenly distributed particles. This increases the charge transfer resistance within the material, significantly reducing its fast-charging performance and failing to meet the low impedance requirements of super-fast charging scenarios. Furthermore, existing technologies often use ordinary petroleum asphalt as the coating raw material. This type of asphalt has a low carbon residue rate, and the coating layer formed after carbonization is prone to defects such as pinholes and cracks, failing to effectively isolate the electrolyte from direct contact with the substrate, resulting in poor material performance during long-term cycling. The rapid capacity decay and poor cycle stability of medium-sulfur coke are significant challenges. Traditional mixing processes often employ low-speed stirring, which fails to adequately disperse the coating agent and substrate, leading to agent agglomeration and exposed substrate surfaces. This results in uneven material performance, further exacerbating capacity loss during cycling and impacting overall material reliability. Existing substrate pretreatment schemes lack specificity and fail to tailor treatment to substrates with different compositions. For example, inadequate desulfurization of medium-sulfur coke can leave impurities on the substrate surface, affecting the interfacial bonding between the coating layer and the substrate, reducing initial charge-discharge efficiency, limiting the application scenarios of low-cost substrates, and hindering industrial cost control. Current technologies generally neglect interfacial optimization of the substrate surface. Residual carbon deposits, ash, and other impurities on the substrate surface weaken the bonding strength between the coating layer and the substrate, causing the coating layer to easily detach or develop microcracks during cycling, further deteriorating the material's cycle stability and charge transport efficiency, making it difficult to meet long-term usage requirements.

[0004] In summary, existing super-fast charging material preparation technologies have significant shortcomings in terms of coating agent control, coating layer quality, mixing uniformity, substrate compatibility, and interfacial bonding. There is an urgent need for a new preparation technology that can overcome these bottlenecks to achieve a significant improvement in the overall performance of super-fast charging materials. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a nano-coated super-fast charging material and its preparation method.

[0006] To achieve the above objectives, the present invention provides the following technical solutions.

[0007] A method for preparing a nano-coated super-fast charging material includes the following steps:

[0008] (1) Substrate pretreatment: Select raw materials for grinding, and after grinding, shape the materials to screen out particles of a specific size. The shaped particles are loaded into a high-temperature graphitization furnace, and argon gas is introduced as a protective gas. The temperature is raised to the set temperature and then kept at that temperature. The material is then naturally cooled to room temperature to obtain a graphitized substrate.

[0009] (2) Preparation of nano-coating agent: High carbon residue pitch was selected and added to a closed detonation vessel. After the vessel door was closed, nitrogen was introduced to remove air. Acetylene and oxygen mixed detonating agent was prepared according to the set ratio and slowly introduced into the detonation vessel. After standing, the mixed detonating agent was ignited to carry out the detonation reaction. After the reaction was completed, the cooling system was turned on to lower the temperature inside the vessel to the set low temperature and keep it warm. Pitch powder was collected from the bottom of the vessel. The pitch powder was added to an ultrasonic disperser and deionized water was added for dispersion. After dispersion, the solid powder was collected by centrifugation to obtain nano-pitch coating agent.

[0010] (3) High-speed fusion coating: Weigh the graphitized substrate and nano-asphalt coating agent according to the set mass ratio, add them to the high-speed mixer, close the mixer cover and set the speed and fusion time for fusion. During the fusion process, observe the dispersion state of the material to ensure that there is no obvious agglomeration. After the fusion is completed, take out the material to obtain the coating precursor;

[0011] (4) Carbonization treatment: The coating precursor is loaded into a quartz boat and placed in a tube furnace. After the furnace door is closed, nitrogen gas is introduced to remove the air in the furnace. The heating program is set to raise the temperature from room temperature to the set carbonization temperature and hold it. After the holding is completed, the heating device is turned off and the nitrogen atmosphere is maintained until the temperature in the furnace drops to room temperature. The quartz boat is then removed to obtain the nano-coated super fast charging material.

[0012] Preferably, the raw material in step (1) is high-purity needle coke or medium-sulfur coke.

[0013] Preferably, when the raw material in step (1) is medium-sulfur coke, the holding time is extended during graphitization in a high-temperature graphitization furnace to enhance the desulfurization effect.

[0014] Preferably, the carbon residue of the high carbon residue pitch described in step (2) is not less than 60%.

[0015] Preferably, in step (2), nitrogen gas is introduced after the sealed detonation vessel door is closed, so that the pressure inside the vessel reaches 5 to 7 MPa; the volume ratio of the acetylene and oxygen mixed detonation agent is 1:2 to 1:2.5.

[0016] Preferably, after the detonation reaction is completed in step (2), the vessel cooling system is turned on to reduce the temperature inside the vessel to -8 to -5°C; the ultrasonic power of the ultrasonic disperser during ultrasonic dispersion is 200 to 350W.

[0017] Preferably, the high-speed mixer in step (3) is a paddle-type high-speed mixer with a set mixing speed of 500 to 700 revolutions per minute and a set fusion time of 30 to 90 minutes.

[0018] Preferably, in step (3), while weighing the graphitized substrate and the nano-asphalt coating agent, carbon black conductive agent is also added, and the three are added together to a paddle-type high-speed mixer for fusion.

[0019] Preferably, in step (4), the heating rate of the tubular furnace is 3 to 5°C per minute, the carbonization temperature is set to 800 to 1000°C, and the holding time is set to 1 to 3 hours.

[0020] Preferably, after obtaining the graphitized substrate in step (1), the graphitized substrate is sent to a plasma cleaner and argon gas is introduced as the working gas for plasma treatment. After the treatment is completed, the substrate is taken out for subsequent steps.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention uses the detonation method to prepare nano-coating agents, effectively breaking through the technical bottleneck of uncontrolled particle size in the traditional ball milling method. It can achieve precise control of the coating agent particle size, significantly reduce the charge transfer resistance inside the material, provide core guarantee for the material's excellent super-fast charging performance, and solve the defect of insufficient fast charging capability caused by the coating agent particle size problem in the existing technology.

[0023] 2. This invention selects high residual carbon asphalt as the coating agent raw material. After carbonization treatment, the raw material can form a dense coating layer without pinholes and cracks, which can effectively isolate the direct contact between the electrolyte and the substrate, greatly reduce the capacity decay of the material during long-term cycling, significantly improve the cycling stability of the material, and overcome the problems of poor density and short cycle life of existing ordinary petroleum asphalt coating layers.

[0024] 3. This invention adopts a high-speed fusion process. By reasonably controlling the mixing speed and time, the coating agent and the substrate are fully dispersed, completely avoiding the agglomeration of the coating agent and ensuring that there is no bare surface on the substrate. This effectively guarantees the uniformity and stability of the material performance and solves the defects of uneven coating and large performance fluctuation caused by traditional low-speed stirring processes.

[0025] 4. This invention develops customized pretreatment solutions for different types of substrates. For example, it optimizes graphitization parameters for low-cost substrates such as medium-sulfur coke to enhance desulfurization, effectively optimizes substrate characteristics, improves the compatibility between substrates and coating agents, successfully expands the application scenarios of low-cost substrates, significantly reduces industrialization costs, and enhances the market competitiveness of materials.

[0026] 5. The optional plasma pretreatment step of this invention can effectively remove residual carbon deposits, ash and other impurities on the substrate surface, significantly enhance the interfacial bonding between the coating layer and the substrate, prevent the coating layer from falling off or generating microcracks during cycling, and improve the first charge and discharge efficiency of the material, further optimizing the energy utilization efficiency of the material, thus solving the problems of poor interfacial bonding and low charge and discharge efficiency in the prior art. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1:

[0029] Substrate pretreatment:

[0030] High-purity needle coke with 0.08% ash content and 0.25% sulfur content was selected as raw material and ground using a planetary ball mill of model XQM-4L. The ball-to-material ratio was set to 10:1, the rotation speed was 300 rpm, and the grinding time was 2 hours.

[0031] After grinding, the material is fed into an air classifier of model QLM-100 for shaping. The speed of the classifying wheel is adjusted to 2000 rpm, and needle-shaped coke particles with a particle size of 6-7μm are obtained by screening.

[0032] The shaped particles were loaded into a high-temperature graphitization furnace of model GWL-3000, and argon gas was introduced as a protective gas. The argon gas flow rate was controlled at 5 liters per minute, and the temperature was raised from room temperature to 2800°C at a rate of 10°C / minute. After holding at this temperature for 4 hours, the heating device was turned off, and the material was allowed to cool naturally to room temperature to obtain the graphitized substrate.

[0033] Preparation of nano-coating agents:

[0034] Select high carbon residue pitch with a carbon residue rate of 62% and a softening point of 120℃, weigh 100g and add it to a sealed detonation reactor of model BH-100. After closing the reactor door, introduce nitrogen gas to raise the pressure inside the reactor to 5MPa and maintain the nitrogen atmosphere for 30 minutes to remove air.

[0035] Prepare a mixed detonation agent of acetylene and oxygen at a volume ratio of 1:2, and slowly introduce it into the detonation vessel through a gas pipeline, controlling the gas flow rate at 50 mL / min. After the gas flow is completed, let it stand for 10 minutes.

[0036] Start the ignition device of the detonation vessel, ignite the mixed detonating agent, and after the detonation reaction is completed, turn on the vessel cooling system to lower the temperature inside the vessel to -5℃. After holding the temperature for 20 minutes, collect the asphalt powder at the bottom of the vessel.

[0037] The particle size of the asphalt powder was measured using a laser particle size analyzer of model MS2000, and the result was 5μm. The asphalt powder was then added to an ultrasonic disperser of model KQ-500VDE, along with 500mL of deionized water. The ultrasonic power was set to 300W and the dispersion time was 15 minutes.

[0038] After dispersion, the solid powder was collected by centrifugation at 8000 rpm for 10 minutes. The powder particle size was observed to be 45-50 nm by a TEM-2100 transmission electron microscope, thus obtaining the nano-asphalt coating agent.

[0039] High-speed fusion coating:

[0040] Weigh 980g of graphitized substrate and 20g of nano-asphalt coating agent in a mass ratio of 98:2, add them to a GHJ-50 paddle-type high-speed mixer, close the mixer cover, set the speed to 600 rpm, and the blending time to 30 minutes.

[0041] During the fusion process, the observation window of the mixer is opened every 10 minutes to observe the dispersion of the materials and ensure that there is no obvious agglomeration. After the fusion is completed, the materials are taken out to obtain a uniformly coated precursor.

[0042] Carbonization treatment:

[0043] The coating precursor was loaded into a quartz boat and placed into a tube furnace of model GSL-1700X. After the furnace door was closed, nitrogen was introduced and the nitrogen flow rate was controlled at 3 liters per minute. The furnace was purged for 30 minutes to remove air from the furnace.

[0044] Set the heating program for the tube furnace: heat from room temperature to 900℃ at a heating rate of 5℃ / minute, and hold at the target temperature for 2 hours after reaching the target temperature;

[0045] After the heat preservation is completed, the heating device is turned off, and the nitrogen atmosphere is maintained until the temperature inside the furnace drops to room temperature. The quartz boat is then removed, and the nano-coated super fast charging material is obtained.

[0046] Example 2:

[0047] Substrate pretreatment:

[0048] Medium-sulfur coke with 0.15% ash content and 1.2% sulfur content was selected as raw material and ground using a planetary ball mill of model XQM-4L. The ball-to-material ratio was set to 10:1, the rotation speed was 300 rpm, and the grinding time was 2 hours.

[0049] After grinding, the material is fed into an air classifier of model QLM-100 for shaping. The speed of the classifying wheel is adjusted to 2000 rpm, and medium-sulfur coke particles with a particle size of 6-7μm are obtained by screening.

[0050] The shaped particles were loaded into a GWL-3000 high-temperature graphitization furnace, and argon gas was introduced as a protective gas. The argon gas flow rate was controlled at 5 liters per minute, and the temperature was increased from room temperature to 2600℃ at a rate of 10℃ / minute. The temperature was held for 6 hours to enhance the desulfurization effect. After the holding period, the heating device was turned off and the material was allowed to cool naturally to room temperature to obtain the graphitized substrate.

[0051] Preparation of nano-coating agents:

[0052] Select high carbon residue pitch with a carbon residue rate of 62% and a softening point of 120℃, weigh 100g and add it to a sealed detonation reactor of model BH-100. After closing the reactor door, introduce nitrogen gas to raise the pressure inside the reactor to 5MPa and maintain the nitrogen atmosphere for 30 minutes to remove air.

[0053] Prepare a mixed detonation agent of acetylene and oxygen at a volume ratio of 1:2, and slowly introduce it into the detonation vessel through a gas pipeline, controlling the gas flow rate at 50 mL / min. After the gas flow is completed, let it stand for 10 minutes.

[0054] Start the ignition device of the detonation vessel, ignite the mixed detonating agent, and after the detonation reaction is completed, turn on the vessel cooling system to lower the temperature inside the vessel to -5℃. After holding the temperature for 20 minutes, collect the asphalt powder at the bottom of the vessel.

[0055] The particle size of the asphalt powder was measured using a laser particle size analyzer of model MS2000, and the result was 5μm. The asphalt powder was then added to an ultrasonic disperser of model KQ-500VDE, along with 500mL of deionized water. The ultrasonic power was set to 300W and the dispersion time was 15 minutes.

[0056] After dispersion, the solid powder was collected by centrifugation at 8000 rpm for 10 minutes. The powder particle size was observed to be 45-50 nm by a TEM-2100 transmission electron microscope, thus obtaining the nano-asphalt coating agent.

[0057] High-speed fusion coating:

[0058] Weigh 965g of graphitized substrate and 35g of nano-asphalt coating agent with a coating agent content of 3.5%, with a mass ratio of 96.5:3.5. Add them to a GHJ-50 paddle-type high-speed mixer, close the mixer cover, set the speed to 600 rpm, and the blending time to 30 minutes.

[0059] During the fusion process, the observation window of the mixer is opened every 10 minutes to observe the dispersion of the materials and ensure that there is no obvious agglomeration. After the fusion is completed, the materials are taken out to obtain a uniformly coated precursor.

[0060] Carbonization treatment:

[0061] The coating precursor was loaded into a quartz boat and placed into a tube furnace of model GSL-1700X. After the furnace door was closed, nitrogen was introduced and the nitrogen flow rate was controlled at 3 liters per minute. The furnace was purged for 30 minutes to remove air from the furnace.

[0062] Set the heating program for the tube furnace: heat from room temperature to 900℃ at a heating rate of 5℃ / minute, and hold at the target temperature for 2 hours after reaching the target temperature;

[0063] After the heat preservation is completed, the heating device is turned off, and the nitrogen atmosphere is maintained until the temperature inside the furnace drops to room temperature. The quartz boat is then removed, and the nano-coated super fast charging material is obtained.

[0064] Example 3:

[0065] Substrate pretreatment:

[0066] High-purity needle coke with 0.08% ash content and 0.25% sulfur content was selected as raw material and ground using a planetary ball mill of model XQM-4L. The ball-to-material ratio was set to 10:1, the rotation speed was 300 rpm, and the grinding time was 2 hours.

[0067] After grinding, the material is fed into an air classifier of model QLM-100 for shaping. The speed of the classifying wheel is adjusted to 2000 rpm, and needle-shaped coke particles with a particle size of 6-7μm are obtained by screening.

[0068] The shaped particles were loaded into a high-temperature graphitization furnace of model GWL-3000, and argon gas was introduced as a protective gas. The argon gas flow rate was controlled at 5 liters per minute, and the temperature was raised from room temperature to 2800°C at a rate of 10°C / minute. After holding at this temperature for 4 hours, the heating device was turned off, and the material was allowed to cool naturally to room temperature to obtain the graphitized substrate.

[0069] Preparation of nano-coating agents:

[0070] High carbon residue pitch with a carbon residue rate of 65% and a softening point of 125℃ was selected to improve the carbon residue rate and enhance the density of the coating layer. 100g was weighed and added to a sealed detonation reactor of model BH-100. After closing the reactor door, nitrogen gas was introduced to raise the pressure inside the reactor to 7MPa to refine the precursor particle size. The nitrogen atmosphere was maintained for 30 minutes to remove air.

[0071] Prepare an acetylene and oxygen mixed detonation agent at a volume ratio of 1:2.2 to optimize the detonation intensity. Slowly introduce the mixture into the detonation vessel through a gas pipeline, controlling the gas flow rate at 50 mL / min. After the gas flow is completed, let it stand for 10 minutes.

[0072] Start the ignition device of the detonation vessel and ignite the mixed detonating agent. After the detonation reaction is completed, turn on the vessel cooling system to lower the temperature inside the vessel to -8°C to reduce particle agglomeration. After holding the temperature for 20 minutes, collect the asphalt powder at the bottom of the vessel.

[0073] The particle size of the asphalt powder was measured using a laser particle size analyzer of model MS2000, and the result was 3μm. The asphalt powder was then added to an ultrasonic disperser of model KQ-500VDE, along with 500mL of deionized water. The ultrasonic power was set to 350W to refine the particle size, and the dispersion time was 12 minutes.

[0074] After dispersion, the solid powder was collected by centrifugation at 8000 rpm for 10 minutes. The powder particle size was observed to be 35-40 nm by a TEM-2100 transmission electron microscope, thus obtaining the nano-asphalt coating agent.

[0075] High-speed fusion coating:

[0076] Weigh 965g of graphitized substrate and 35g of nano-asphalt coating agent in a mass ratio of 96.5:3.5, add them to a GHJ-50 paddle-type high-speed mixer, close the mixer cover, set the speed to 600 rpm, and the blending time to 60 minutes to improve the dispersion uniformity.

[0077] During the fusion process, the observation window of the mixer is opened every 15 minutes to observe the dispersion of the materials and ensure that there is no obvious agglomeration. After the fusion is completed, the materials are taken out to obtain a uniformly coated precursor.

[0078] Carbonization treatment:

[0079] The coating precursor was loaded into a quartz boat and placed into a tube furnace of model GSL-1700X. After the furnace door was closed, nitrogen was introduced and the nitrogen flow rate was controlled at 3 liters per minute. The furnace was purged for 30 minutes to remove air from the furnace.

[0080] Set the heating program for the tube furnace: heat from room temperature to 900℃ at a heating rate of 5℃ / minute, and hold at the target temperature for 2 hours after reaching the target temperature;

[0081] After the heat preservation is completed, the heating device is turned off, and the nitrogen atmosphere is maintained until the temperature inside the furnace drops to room temperature. The quartz boat is then removed, and the nano-coated super fast charging material is obtained.

[0082] Example 4:

[0083] Substrate pretreatment:

[0084] High-purity needle coke with 0.08% ash content and 0.25% sulfur content was selected as raw material and ground using a planetary ball mill of model XQM-4L. The ball-to-material ratio was set to 10:1, the rotation speed was 300 rpm, and the grinding time was 2 hours.

[0085] After grinding, the material is fed into an air classifier of model QLM-100 for shaping. The speed of the classifying wheel is adjusted to 2000 rpm, and needle-shaped coke particles with a particle size of 6-7μm are obtained by screening.

[0086] The shaped particles were loaded into a high-temperature graphitization furnace of model GWL-3000, and argon gas was introduced as a protective gas. The argon gas flow rate was controlled at 5 liters per minute, and the temperature was increased from room temperature to 2900°C at a rate of 10°C / minute to reduce the substrate resistance. After holding at the temperature for 4 hours, the heating device was turned off and the material was allowed to cool naturally to room temperature to obtain the graphitized substrate.

[0087] The graphitized substrate was fed into a PT-500 plasma cleaner, with argon gas introduced as the working gas. The argon gas flow rate was controlled at 200 mL / min, the plasma power was set at 500 W, and the treatment time was 10 minutes to remove residual carbon deposits and ash from the substrate surface. After treatment, the substrate was removed for later use.

[0088] Preparation of nano-coating agents:

[0089] Select high carbon residue pitch with a carbon residue rate of 65% and a softening point of 125℃, weigh 100g and add it to a sealed detonation reactor of model BH-100. After closing the reactor door, introduce nitrogen gas to raise the pressure inside the reactor to 7MPa and maintain the nitrogen atmosphere for 30 minutes to remove air.

[0090] Prepare an acetylene and oxygen mixed detonation agent at a volume ratio of 1:2.2, and slowly introduce it into the detonation vessel through a gas pipeline, controlling the gas flow rate at 50 mL / min. After the gas flow is completed, let it stand for 10 minutes.

[0091] Start the ignition device of the detonation vessel, ignite the mixed detonating agent, and after the detonation reaction is completed, turn on the vessel cooling system to lower the temperature inside the vessel to -8℃. After holding the temperature for 20 minutes, collect the asphalt powder at the bottom of the vessel.

[0092] The particle size of the asphalt powder was measured using a laser particle size analyzer of model MS2000, and the result was 3μm. The asphalt powder was then added to an ultrasonic disperser of model KQ-500VDE, along with 500mL of deionized water. The ultrasonic power was set to 350W and the dispersion time was 12 minutes.

[0093] After dispersion, the solid powder was collected by centrifugation at 8000 rpm for 10 minutes. The powder particle size was observed to be 35-40 nm by a TEM-2100 transmission electron microscope, thus obtaining the nano-asphalt coating agent.

[0094] High-speed fusion coating:

[0095] Weigh 950g of graphitized substrate and 50g of nano-asphalt coating agent with a mass ratio of 95:5 and a coating agent content of 5% to verify the upper limit. Add them to a GHJ-50 paddle-type high-speed mixer, close the mixer cover, set the speed to 700 rpm to enhance the dispersion effect, and set the fusion time to 90 minutes to verify the longest fusion time.

[0096] During the fusion process, the observation window of the mixer is opened every 15 minutes to observe the dispersion of the materials and ensure that there is no obvious agglomeration. After the fusion is completed, the materials are taken out to obtain a uniformly coated precursor.

[0097] Carbonization treatment:

[0098] The coating precursor was loaded into a quartz boat and placed into a tube furnace of model GSL-1700X. After the furnace door was closed, nitrogen was introduced and the nitrogen flow rate was controlled at 3 liters per minute. The furnace was purged for 30 minutes to remove air from the furnace.

[0099] Set the heating program for the tube furnace: heat from room temperature to 1000℃ at a heating rate of 5℃ / min to enhance the strength of the coating layer, and hold at the target temperature for 3 hours to ensure sufficient carbonization.

[0100] After the heat preservation is completed, the heating device is turned off, and the nitrogen atmosphere is maintained until the temperature inside the furnace drops to room temperature. The quartz boat is then removed, and the nano-coated super fast charging material is obtained.

[0101] Example 5:

[0102] Substrate pretreatment:

[0103] Medium-sulfur coke with 0.15% ash content and 1.0% sulfur content was selected as raw material and ground using a planetary ball mill of model XQM-4L. The ball-to-material ratio was set to 10:1, the rotation speed was 300 rpm, and the grinding time was 2 hours.

[0104] After grinding, the material is fed into an air classifier of model QLM-100 for shaping. The speed of the classifying wheel is adjusted to 2000 rpm, and medium-sulfur coke particles with a particle size of 6-7μm are obtained by screening.

[0105] The shaped particles were loaded into a high-temperature graphitization furnace of model GWL-3000, and argon gas was introduced as a protective gas. The argon gas flow rate was controlled at 5 liters per minute, and the temperature was raised from room temperature to 2700°C at a rate of 10°C / minute. After holding at this temperature for 5 hours, the heating device was turned off, and the material was allowed to cool naturally to room temperature to obtain the graphitized substrate.

[0106] The graphitized substrate was fed into a PT-500 plasma cleaner, with argon gas introduced as the working gas. The argon gas flow rate was controlled at 200 mL / min, the plasma power was set at 400 W, and the treatment time was 8 minutes. After the treatment was completed, the substrate was removed for later use.

[0107] Preparation of nano-coating agents:

[0108] High carbon residue pitch with a carbon residue rate of 60% and a softening point of 110℃ was selected to verify the lower limit of carbon residue rate. 100g was weighed and added to a sealed detonation reactor of model BH-100. After closing the reactor door, nitrogen gas was introduced to raise the pressure inside the reactor to 6MPa. The nitrogen atmosphere was maintained for 30 minutes to remove air.

[0109] Prepare an acetylene and oxygen mixed detonation agent at a volume ratio of 1:2.5 to verify the upper limit of the detonation agent ratio. Slowly introduce the mixture into the detonation vessel through a gas pipeline, controlling the gas flow rate at 50 mL / min. After the gas flow is completed, let it stand for 10 minutes.

[0110] Start the ignition device of the detonation vessel, ignite the mixed detonating agent, and after the detonation reaction is completed, turn on the vessel cooling system to lower the temperature inside the vessel to -5℃. After holding the temperature for 20 minutes, collect the asphalt powder at the bottom of the vessel.

[0111] The particle size of the asphalt powder was measured using a laser particle size analyzer of model MS2000, and the result was 4μm. The asphalt powder was then added to an ultrasonic disperser of model KQ-500VDE, along with 500mL of deionized water. The ultrasonic power was set to 200W to verify the lower limit of the ultrasonic power, and the dispersion time was set to 20 minutes to verify the maximum ultrasonic time.

[0112] After dispersion, the solid powder was collected by centrifugation at 8000 rpm for 10 minutes. The powder particle size was observed to be 40-45 nm by a TEM-2100 transmission electron microscope, thus obtaining the nano-asphalt coating agent.

[0113] High-speed fusion coating:

[0114] Weigh out 970g of graphitized substrate, 30g of nano-asphalt coating agent with a mass ratio of 97:3, and 5g of SuperP carbon black conductive agent with a mass percentage of 0.5%. Add them to a GHJ-50 paddle-type high-speed mixer, close the mixer cover, set the speed to 500 rpm to verify the lower limit of the fusion speed, and the fusion time is 45 minutes.

[0115] During the fusion process, the observation window of the mixer is opened every 15 minutes to observe the dispersion of the materials and ensure that neither the conductive agent nor the coating agent agglomerates. After the fusion is completed, the materials are removed to obtain a uniformly coated precursor.

[0116] Carbonization treatment:

[0117] The coating precursor was loaded into a quartz boat and placed into a tube furnace of model GSL-1700X. After the furnace door was closed, nitrogen was introduced and the nitrogen flow rate was controlled at 3 liters per minute. The furnace was purged for 30 minutes to remove air from the furnace.

[0118] Set the heating program for the tube furnace: heat from room temperature to 800℃ at a heating rate of 3℃ / min to verify the lower limit of the heating rate; hold at the target temperature for 1 hour after reaching the target temperature to verify the lower limit of the holding time.

[0119] After the heat preservation is completed, the heating device is turned off, and the nitrogen atmosphere is maintained until the temperature inside the furnace drops to room temperature. The quartz boat is then removed, and the nano-coated super fast charging material is obtained.

[0120] Comparative Example 1:

[0121] A control scheme lacking detonation was used, and the coating agent was prepared using conventional ball milling;

[0122] Substrate pretreatment: completely consistent with Example 1, that is, high-purity needle coke with 0.08% ash content and 0.25% sulfur content is selected, and it is ground by a planetary ball mill of model XQM-4L, shaped by an air classifier of model QLM-100, and graphitized at 2800℃ in a high-temperature graphitization furnace of model GWL-3000.

[0123] Coating agent preparation: Without detonation, high carbon residue pitch (62%), the same as in Example 1, was selected. 100g was weighed and added to a standard ball mill (model QM-3SP4). Agate balls were added, and the ball-to-powder ratio was set to 8:1. The milling speed was set to 400 rpm for 4 hours. After milling, the particle size of the pitch powder was measured using a laser particle size analyzer (model MS2000) and found to be 10-15 μm. The subsequent ultrasonic dispersion step was the same as in Example 1, using an ultrasonic disperser (model KQ-500VDE) at 300W power for 15 minutes. The particle size of the coating agent was observed using a transmission electron microscope (model TEM-2100) and found to be 80-120 nm.

[0124] High-speed fusion coating: exactly the same as in Example 1, that is, the substrate and coating agent are mixed at a mass ratio of 98:2, and added to a high-speed mixer of model GHJ-50, and fused at a speed of 600 rpm for 30 minutes;

[0125] Carbonization treatment: exactly the same as in Example 1, i.e., using a tube furnace of model GSL-1700X, carbonized at 900°C for 2 hours.

[0126] Comparative Example 2:

[0127] The control scheme, which lacks high residual carbon asphalt, uses ordinary petroleum asphalt;

[0128] Substrate pretreatment: exactly the same as in Example 1;

[0129] Coating agent preparation: Ordinary petroleum asphalt with a carbon residue rate of 35% and a softening point of 90℃ was selected and prepared using the same detonation method as in Example 1. That is, it was detonated in a closed detonation kettle of model BH-100 under a pressure of 5MPa and dispersed in an ultrasonic disperser of model KQ-500VDE. The particle size of the coating agent was tested to be 45-50nm.

[0130] High-speed fusion coating: completely consistent with Example 1;

[0131] Carbonization treatment: exactly the same as in Example 1.

[0132] Comparative Example 3:

[0133] A control scheme lacking high-speed fusion: using low-speed stirring and mixing.

[0134] Substrate pretreatment: exactly the same as in Example 1;

[0135] Preparation of coating agent: Completely consistent with Example 1, that is, 45-50nm nano-asphalt coating agent was prepared by detonation method;

[0136] Fusion and coating: Instead of using a high-speed mixer, a regular stirring paddle of model JJ-1 was used, with the speed set to 200 rpm and the stirring time set to 30 minutes. The remaining operations were the same as the high-speed fusion and coating steps in Example 1.

[0137] Carbonization treatment: exactly the same as in Example 1.

[0138] Comparative Example 4:

[0139] The control scheme had inappropriate substrate parameters; the graphitization parameters of the medium-sulfur coke were not adjusted.

[0140] Substrate pretreatment: Medium-sulfur coke with the same ash content of 0.15% and sulfur content as in Example 2 was selected. After grinding and shaping, the graphitization parameters of Example 1 were used, that is, it was heated at 2800°C for 4 hours in a high-temperature graphitization furnace of model GWL-3000 without extending the holding time; the remaining grinding and shaping steps were the same as in Example 2.

[0141] Preparation of coating agent: Completely consistent with Example 2, i.e., preparing 45-50nm nano-asphalt coating agent at a mass ratio of 3.5%;

[0142] High-speed fusion coating: completely consistent with Example 2;

[0143] Carbonization treatment: exactly the same as in Example 2.

[0144] Comparative Example 5:

[0145] A comparative scheme of missing interface optimization and low residual carbon coating agent;

[0146] Substrate pretreatment: Same as in Example 4, i.e., graphitization at 2900°C using a GWL-3000 high-temperature graphitization furnace, but omitting the plasma pretreatment step;

[0147] Coating agent preparation: Low carbon residue asphalt with a carbon residue rate of 55% was selected and prepared by the detonation method in Example 4, that is, by detonation in a closed detonation vessel of model BH-100 at a pressure of 7MPa and dispersion in an ultrasonic disperser of model KQ-500VDE to obtain a coating agent of 35-40nm.

[0148] High-speed fusion coating: exactly the same as in Example 4, i.e., mixed at a mass ratio of 95:5 and fused at a speed of 700 rpm for 90 minutes;

[0149] Carbonization treatment: exactly the same as in Example 4, i.e. carbonization at 1000°C for 3 hours.

[0150] The performance tests and results analysis are as follows:

[0151] (1) Test method

[0152] 10C rate charging time test:

[0153] The materials of each embodiment and comparative example were made into negative electrode sheets: active material, polyvinylidene fluoride (PVDF) binder, and carbon black conductive agent of type SuperP were mixed in a mass ratio of 95:3:2, and N-methylpyrrolidone (NMP) was added to prepare a slurry.

[0154] The slurry was evenly coated onto the copper foil using an MT-KC300 coating machine, dried in an 80℃ oven for 12 hours, and then compacted using an MT-400 roller press to a compaction density of 1.6 g / cm³. 3 Cut into electrode sheets with a diameter of 12mm;

[0155] A CR2032 coin cell was assembled in an argon-filled glove box of model LABstar with an 11 mm diameter LiCoO2 cathode, a Celgard 2400 separator, and a 1 mol / L LiPF6 electrolyte in which the solvent is EC:DMC:EMC=1:1:1.

[0156] A CT2001A battery tester was used to charge the battery from 0% SOC to 100% SOC at a constant current of 10C, with the cutoff voltage set at 4.2V, and the charging time was recorded.

[0157] Cyclic stability test:

[0158] Using the above-mentioned button cell battery, the cycle is set as follows: 10C constant current charging to 4.2V with a cutoff current of 0.05C, then rest for 5 minutes; 10C constant current discharging to 2.5V with a cutoff current of 0.05C, then rest for 5 minutes.

[0159] After 1000 cycles, the discharge capacity of the 1000th cycle is tested, and the capacity retention rate is calculated as (1000th cycle discharge capacity / first discharge capacity × 100%).

[0160] First charge / discharge efficiency test:

[0161] Using the above-mentioned button cell battery, charge it to 4.2V with a constant current of 0.1C and a cutoff current of 0.05C, and record the capacity of the first charge.

[0162] Discharge at a constant current of 0.1C to 2.5V with a cutoff current of 0.05C, and record the initial discharge capacity;

[0163] Calculate the initial charge / discharge efficiency (initial discharge capacity / initial charge capacity × 100%).

[0164] Electrode impedance test:

[0165] The above coin cells were subjected to AC impedance spectroscopy (EIS) testing using a CHI660E electrochemical workstation.

[0166] The test conditions are set to a frequency range of 10. -2 -10 5 Hz, amplitude 5mV, resting time 30 minutes;

[0167] The equivalent circuit was fitted using Zview software, and the charge transfer impedance Rct was extracted.

[0168] Coating and substrate property testing:

[0169] The surface morphology of the material was observed using a scanning electron microscope (SEM-SU8010), and the coating thickness, uniformity, and defects such as cracks and pinholes were analyzed.

[0170] The sulfur content on the surface of the substrate was detected using an XPS-K-Alpha X-ray photoelectron spectroscopy instrument, specifically for testing medium-sulfur coke substrates.

[0171] The degree of graphitization of the coating layer was analyzed using a RenishawinVia Raman spectrometer, and characterized by the intensity ratio of the D peak to the G peak, ID / IG.

[0172] The test results are shown in Table 1 below:

[0173] Group 10C charging time (minutes) Capacity retention rate after 1000 cycles (%) First charge / discharge efficiency (%) Charge transfer impedance (milliohms) Coating thickness (nanometers) Sulfur content (%) on substrate surface Overlay ID / IG Coating condition (SEM observation) Example 1 6.2 85 92 95 45-50 - 0.82 Uniform, crack-free, and free of agglomeration Example 2 6.0 88 92 90 50-55 0.05 0.80 Improved density, no pinholes Example 3 5.8 90 93 80 35-40 - 0.78 Evenly dispersed, with tight interfacial bonding Example 4 5.5 92 94 70 40-45 - 0.75 No gaps, high coating strength Example 5 5.7 91 93 75 42-46 0.04 0.77 The conductive agent is uniformly dispersed, with no exposed substrate. Comparative Example 1 7.5 70 88 180 80-120 - 0.95 Localized cracking, uneven coating Comparative Example 2 7.2 72 90 150 20-30 - 1.02 Pinholes are present, and the coating layer is loose. Comparative Example 3 8.0 65 87 200 irregular - 0.98 The coating agent agglomerates, exposing 30% of the substrate. Comparative Example 4 7.6 72 85 170 45-50 0.35 0.85 Sulfur residue caused the coating layer to become loose. Comparative Example 5 6.8 78 91 120 38-42 - 0.90 Localized microcracks, impurities at the interface

[0174] The results are analyzed as follows:

[0175] The various embodiments of this invention are based on the same core technical route: detonation method for preparing nano-coating agents + high-carbon-residue asphalt coating + high-speed fusion + gradient carbonization, forming a progressive relationship: Example 2 adapts medium-sulfur coke and adjusts the coating agent content based on Example 1; Example 3 optimizes the detonation parameters and fusion time based on Example 2; Example 4 increases the carbonization temperature and adds plasma pretreatment based on Example 3; Example 5 combines medium-sulfur coke with conductive agent doping based on Example 4. The steps are closely connected and the parameters are orderly correlated. Comparative Example 1, lacking the detonation method, uses ordinary ball milling to prepare coating agent particles with a size of 80-120 nm, far exceeding the control range of no more than 50 nm of this invention, causing the charge transfer impedance to soar to 180 milliohms and the 10C charging time to be extended to 7.5 minutes, proving that the detonation method is the key to accurately controlling the coating agent particle size and reducing the interfacial impedance; Comparative Example 2, using ordinary petroleum asphalt with a carbon residue rate of 35%, has a loose coating layer with pinholes after carbonization. The capacity retention rate after 1000 cycles was only 72%, proving the necessity of high carbon residue pitch of no less than 60% for improving the density of the coating layer and ensuring cycle stability. Comparative Example 3, due to the use of low-speed stirring at 200 rpm instead of high-speed fusion, resulted in coating agent agglomeration and 30% exposed substrate area, with impedance rising to 200 milliohms, proving that high-speed fusion at 500-700 rpm is the core to achieve uniform dispersion of the coating agent and avoid substrate exposure. Comparative Example 4, due to the failure to adjust graphitization parameters and extend the heat preservation time for medium-sulfur coke, had a residual sulfur content of 0.35% on the substrate surface, resulting in loose coating layer bonding and an initial charge-discharge efficiency of only 85%, proving that customized substrate pretreatment parameters are the basis for adapting to different substrates and optimizing interface bonding. Comparative Example 5, due to the lack of plasma pretreatment and the use of low carbon residue pitch, showed local microcracks in the coating layer, residual impurities at the interface, and a cycle retention rate reduced to 78%, proving the importance of the synergistic effect of interface optimization steps and high carbon residue coating agents for performance improvement.

[0176] This invention overcomes the technical bottleneck of particle size control in traditional ball milling by precisely preparing nano-coating agents through detonation method; expands the application scenarios of low-cost medium-sulfur coke through customized substrate pretreatment; and solves the industry problem of interfacial bonding between coating layer and substrate through high-speed fusion and plasma pretreatment.

[0177] All embodiments achieve a 10C charging time of ≤6.2 minutes, a capacity retention rate of ≥85% after 1000 cycles, and an initial charge-discharge efficiency of ≥92%, which are significantly better than comparative examples and existing technologies. They achieve a synergistic improvement in super-fast charging, high cycle stability, and low-cost adaptability, and have significant technical advantages and industrialization value.

[0178] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only to the claims and their full scope and equivalents.

Claims

1. A method for preparing a nano-coated superfast charging material, characterized in that, Includes the following steps: (1) Substrate pretreatment: Select raw materials for grinding, and after grinding, shape the materials to screen out particles of a specific size. The shaped particles are loaded into a high-temperature graphitization furnace, and argon gas is introduced as a protective gas. The temperature is raised to the set temperature and then kept at that temperature. The material is then naturally cooled to room temperature to obtain a graphitized substrate. (2) Preparation of nano-coating agent: High carbon residue pitch was selected and added to a closed detonation vessel. After the vessel door was closed, nitrogen was introduced to remove air. Acetylene and oxygen mixed detonating agent was prepared according to the set ratio and slowly introduced into the detonation vessel. After standing, the mixed detonating agent was ignited to carry out the detonation reaction. After the reaction was completed, the cooling system was turned on to lower the temperature inside the vessel to the set low temperature and keep it warm. Pitch powder was collected from the bottom of the vessel. The pitch powder was added to an ultrasonic disperser and deionized water was added for dispersion. After dispersion, the solid powder was collected by centrifugation to obtain nano-pitch coating agent. (3) High-speed fusion coating: Weigh the graphitized substrate and nano-asphalt coating agent according to the set mass ratio, add them to the high-speed mixer, close the mixer cover and set the speed and fusion time for fusion. During the fusion process, observe the dispersion state of the material to ensure that there is no obvious agglomeration. After the fusion is completed, take out the material to obtain the coating precursor; (4) Carbonization treatment: The coating precursor is loaded into a quartz boat and placed in a tube furnace. After the furnace door is closed, nitrogen gas is introduced to remove the air in the furnace. The heating program is set to raise the temperature from room temperature to the set carbonization temperature and hold it. After the holding is completed, the heating device is turned off and the nitrogen atmosphere is maintained until the temperature in the furnace drops to room temperature. The quartz boat is then removed to obtain the nano-coated super fast charging material.

2. The preparation method according to claim 1, characterized in that, The raw material mentioned in step (1) is high-purity needle coke or medium-sulfur coke.

3. The preparation method according to claim 2, characterized in that, When the raw material mentioned in step (1) is medium-sulfur coke, the holding time is extended during the graphitization process in the high-temperature graphitization furnace to enhance the desulfurization effect.

4. The preparation method according to claim 1, characterized in that, The carbon residue of the high carbon residue pitch mentioned in step (2) shall not be less than 60%.

5. The preparation method according to claim 1, characterized in that, In step (2), nitrogen gas is introduced after the sealed detonation vessel door is closed, so that the pressure inside the vessel reaches 5 to 7 MPa; the volume ratio of the acetylene and oxygen mixed detonation agent is 1:2 to 1:2.

5.

6. The preparation method according to claim 1, characterized in that, After the detonation reaction is completed in step (2), the vessel cooling system is turned on to reduce the temperature inside the vessel to -8 to -5℃; the ultrasonic power of the ultrasonic disperser during ultrasonic dispersion is 200 to 350W.

7. The preparation method according to claim 1, characterized in that, The high-speed mixer mentioned in step (3) is a paddle-type high-speed mixer with a set mixing speed of 500 to 700 revolutions per minute and a set fusion time of 30 to 90 minutes.

8. The preparation method according to claim 7, characterized in that, In step (3), while weighing the graphitized substrate and the nano-asphalt coating agent, carbon black conductive agent is also added, and the three are added together to a paddle-type high-speed mixer for fusion.

9. The preparation method according to claim 1, characterized in that, In step (4), the heating rate of the tubular furnace is 3 to 5°C per minute, the carbonization temperature is set to 800 to 1000°C, and the holding time is set to 1 to 3 hours.

10. The preparation method according to claim 1, characterized in that, After obtaining the graphitized substrate in step (1), the graphitized substrate is sent to a plasma cleaner and argon gas is introduced as the working gas for plasma treatment. After the treatment is completed, the substrate is taken out for subsequent steps.