A pulverization process of a derivative biomass hard carbon material

Abstract

The application discloses a kind of derived biomass hard carbon material pulverization process, belong to biomass charcoal material processing technical field, first, pulverization process includes the following steps: after drying, the coconut shell derived hard carbon block is carried out primary crushing, while spraying first modifier, obtain the particle size 1~3mm of coarse crushing modified particle;Coarse crushing modified particle is carried out secondary precision crushing under argon atmosphere, while spraying second modifier, obtain the precision crushing modified particle of D 50 Particle size is 15 μm;Precision crushing modified particle is carried out roll grinding spheroidization, while spraying third modifier, obtain the spherical modified particle of D 50 Particle size is 10 μm;Spherical modified particle is carried out flash drying after cooling, then add magnesium stearate to it, after mixing, obtain derived biomass hard carbon material.Then, the application realizes breakthrough in tap density, particle size distribution, first efficiency and other core indexes by the coordination of three-stage gradient modification and progressive pulverization process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biomass charcoal material processing, and particularly relates to a derived biomass hard carbon material powdering process. BACKGROUND

[0002] Biomass hard carbon material has become a research hotspot of lithium ion battery negative materials due to its high specific capacity, low expansion rate and excellent cycle stability. The existing process mainly prepares hard carbon precursors by high-temperature carbonization of agricultural and forestry wastes (such as coconut shells and walnut shells), and then micron-sized powder is obtained through mechanical crushing. The material needs to meet the core indexes such as tap density > 0.8 g / cm 3 , D 50 particle size 2-5 μm and concentrated particle size distribution (Span value < 1.2) in the application of energy storage field, so as to realize the optimization of electrode coating uniformity and battery rate performance.

[0003] The traditional powdering process adopts single high-speed ball milling or airflow crushing, and has the following technical defects: (1) In the ball milling method, a large number of flaky debris are generated in the repeated collision of hard carbon particles, which leads to the reduction of tap density to 0.6-0.7 g / cm 3 , and the flaky particles are prone to form oriented arrangement during coating, which causes local stress concentration of the electrode; (2) Although spherical particles can be obtained by airflow crushing, the specific surface area is too high (> 10 m 2 / g), which leads to the reduction of the first charge and discharge efficiency by 8%-12%.

[0004] With the demand of new energy vehicles for the energy density of power batteries increasing to more than 400 Wh / kg, it is urgent to develop a powdering process with high tap density and narrow particle size distribution. SUMMARY

[0005] The purpose of the present application is to provide a derived biomass hard carbon material powdering process to solve the problems of uncontrolled particle morphology and low tap density in the traditional powdering process.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A derived biomass hard carbon material powdering process comprises the following steps:

[0008] S1, after drying the coconut shell derived hard carbon block, primary crushing is performed while spraying a primary modifier, and after completion, coarse crushed modified particles with a particle size of 1-3 mm are obtained;

[0009] S2, the coarse crushed modified particles are subjected to secondary fine crushing under an argon atmosphere while spraying a secondary modifier, and after completion, fine crushed modified particles with a D 50 particle size of 15 μm are obtained;

[0010] S3, the fine modified particles are roller milled into spherical particles, while spraying a third modifier, after which D is obtained 50 spherical modified particles with a particle size of 10 μm;

[0011] S4, the spherical modified particles are flash dried in a nitrogen atmosphere for 2-3 min, after which they are cooled to room temperature, 0.1 wt% of magnesium stearate is added thereto and mixed for 10 min to obtain the derived biomass hard carbon material.

[0012] Further, the average fixed carbon content of the coconut shell derived hard carbon block is 92.5%.

[0013] Further, the spraying mode of the first modifier is high-pressure atomizing spraying, the pressure of the high-pressure atomizing spraying is 0.3-0.5 MPa, and the flow rate is 5 L / min; the spraying mode of the second modifier is double-fluid atomizing spraying, the compressed air pressure of the double-fluid atomizing spraying is 0.4-0.5 MPa, and the flow rate is 3 L / min; the spraying mode of the third modifier is ultrasonic atomizing; the frequency of the ultrasonic atomizing is 28 kHz, and the flow rate is 2 L / min.

[0014] Further, the first modifier is composed of the following mass percentage raw materials:

[0015] Nano-silicon dioxide 0.8%-1.0%;

[0016] Sodium polyacrylate 0.3%-0.4%;

[0017] Dispersant BYK-180 0.4%-0.5%;

[0018] 1-ethyl-3-methyl imidazole bis-trifluoromethanesulfonyl imidate salt 0.1%-0.2%;

[0019] The balance is deionized water.

[0020] Further, the particle size of the nano-silicon dioxide is 20 nm; and the weight average molecular weight of the sodium polyacrylate is 2100.

[0021] Further, the first modifier is prepared by the following steps:

[0022] Each raw material is weighed according to the mass percentage. The nanometer silicon dioxide is vacuum dried at 80-100℃ for 4-5h, then blended with 1-ethyl-3-methyl imidazole bis-trifluoromethyl sulfonimide salt in an ultrasonic cell crusher for 20-30min to form a pre-dispersed colloid. The dispersant BYK-180 is mixed with deionized water at 45℃ to form a transparent solution. The pre-dispersed colloid is poured into the transparent solution, and a 3000Gs centrifugal shear force is applied simultaneously for 15-20min. Then, the polyacrylic acid sodium is added, and the mixture is stirred and aged under nitrogen protection for 2h to obtain the primary modifier.

[0023] Further, the secondary modifier includes the following mass parts of raw materials:

[0024] Hydroxypropyl methyl cellulose 6-10 parts;

[0025] Polyvinylpyrrolidone K90 3-5 parts;

[0026] Sodium tetraborate 1-2 parts;

[0027] Hydroxylated multi-walled carbon nanotubes 5-8 parts;

[0028] Anhydrous ethanol 150 parts;

[0029] Deionized water 50 parts.

[0030] Further, the viscosity of the hydroxypropyl methyl cellulose is 4000mPa·s; the number average molecular weight of the polyvinylpyrrolidone K90 is 360,000; and the outer diameter of the hydroxylated multi-walled carbon nanotube is 5-15nm, and the length is 10-50μm.

[0031] Further, the secondary modifier is prepared by the following steps:

[0032] Each raw material is weighed by mass parts. Deionized water is added to anhydrous ethanol under stirring, then hydroxypropyl methyl cellulose and polyvinylpyrrolidone K90 are added. The system is heated to 45-50℃, and swelled for 3-5h. After completion, a transparent colloid is obtained. Sodium tetraborate is added to the transparent colloid under stirring, and the pH of the system is adjusted to 9.2-9.5. After completion, the system is filled with nitrogen to replace air, and finally filled with nitrogen to maintain 0.3-0.5MPa. After completion, the system is heated to 55-60℃, and reacted for 4-5h. Then, the hydroxylated multi-walled carbon nanotube is added to the system under stirring, and then treated by a high-pressure homogenizer at 120MPa for 15 cycles, with 30s cooling interval between each cycle. After completion, the secondary modifier is obtained.

[0033] Further, the tertiary modifier includes the following mass parts of raw materials:

[0034] Silane coupling agent KH-550 15-20 parts;

[0035] Silane Coupling Agent KH-792 10-12 parts;

[0036] Alumina Sol 1.2-1.5 parts;

[0037] Polyethylene Glycol 0.05-0.1 parts;

[0038] Deionized Water 200 parts.

[0039] Further, the solid content of the alumina sol is 20%; and the weight average molecular weight of the polyethylene glycol is 6000.

[0040] Further, the tertiary modifier is prepared by the following steps:

[0041] The raw materials are weighed according to the mass parts, the silane coupling agent KH-550 and the silane coupling agent KH-792 are added into the deionized water under stirring, the pH of the system is adjusted to 4.4-4.5, then the pre-hydrolysis silane solution is obtained after stirring and hydrolysis for 4-5 hours; the alumina sol is activated to obtain the activated alumina sol; the pre-hydrolysis silane solution and the activated alumina sol are mixed and heated to 60-65 DEG C, and then stirred for 15-20 minutes, then the polyethylene glycol is added into the mixture under stirring, and ultrasonic treatment is performed for 20-30 minutes to obtain the tertiary modifier.

[0042] Further, the activation treatment comprises the following steps:

[0043] The alumina sol is placed in a plasma reaction chamber, Ar / H2 mixed gas is introduced according to a volume ratio of 9:1, the flow rate is 50 sccm, the radio frequency power is 200 W, the treatment time is 25-30 minutes, and then the activated alumina sol is obtained.

[0044] The beneficial effects of the present application are:

[0045] The present application provides a powdering process of derived biomass hard carbon material, and through the cooperation of three-stage gradient modification and gradual powdering process, breakthroughs are achieved in core indicators such as tap density (>0.83 g / cm 3 , particle size distribution (Span <1.15), and first efficiency (>94%), which provides an ideal hard carbon negative material solution for high-energy density lithium ion batteries. At the same time, the necessity and synergistic effect of each element in the technical scheme of the present application are fully verified by test data, and the specific analysis is as follows:

[0046] First, the powdering process of the present application significantly improves the tap density of the material, and optimizes the electrode coating performance:

[0047] The tap density of the derived biomass hard carbon materials prepared by the pulverization process provided in Examples 10-12 of this invention reaches 0.83-0.89 g / cm³. 3 Comparative examples 4–10 (0.65–0.80 g / cm³) 3 This represents an increase of 23.1% to 36.9%. Specifically:

[0048] (1) Synergistic effect of ionic liquid in primary modifier: Comparative Example 4 (ionic liquid removed) tap density decreased to 0.71 g / cm³. 3 This indicates that 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt promotes dense particle packing by reducing the aggregation of nano-silica;

[0049] (2) Carbon nanotube reinforcing effect of secondary modifier: Comparative Example 6 (hydroxylated multi-walled carbon nanotubes removed) had a tap density of 0.76 g / cm³. 3 This indicates that carbon nanotubes form a three-dimensional network scaffold during the fine crushing process, reducing the porosity between particles;

[0050] (3) Surface nano-coating of tertiary modifier: Comparative Example 8 (unactivated alumina sol) had a tap density of 0.80 g / cm³. 3 This demonstrates that the nano-coating of activated alumina sol reduces surface roughness and enhances particle flowability.

[0051] II. The pulverization process of this invention improves electrode uniformity by precisely controlling particle size distribution:

[0052] The Span value (particle size distribution index) of the derived biomass hard carbon materials prepared by the pulverization process provided in Examples 10-12 of this invention is 1.06-1.15, which is significantly better than the 1.18-1.70 of Comparative Examples 4-10. The specific mechanism includes:

[0053] (1) Synergistic effect of graded crushing and modification: primary crushing (1-3mm) combined with high-pressure atomized spraying (0.3-0.5MPa) achieves uniform pre-modification of coarse particles, avoiding the uneven secondary crushing caused by particle edges in Comparative Example 5 (without primary modifier) ​​(Span value 1.50).

[0054] (2) Dispersing effect of hydroxylated multi-walled carbon nanotubes: The Span value of Comparative Example 6 (without carbon nanotubes) increased to 1.25, indicating that carbon nanotubes inhibit the agglomeration of finely broken particles through physical isolation effect;

[0055] (3) Ultrasonic atomization-assisted spheroidization: In Example 12, the tertiary modifier was uniformly coated on the particle surface by ultrasonic atomization at 28 kHz. Compared with Comparative Example 10 (tertiary treatment omitted), the Span value reached 1.70, proving that the spheroidization treatment eliminated flaky debris and achieved monodisperse spherical particles.

[0056] Third, the pulverization process of this invention reduces the specific surface area of ​​the material and improves the initial charge-discharge efficiency:

[0057] The specific surface area of ​​the derived biomass hard carbon materials prepared by the pulverization process provided in Examples 10-12 of this invention is 6.4-7.1 m². 2 / g) compared to traditional processes (>10m) 2 / g) reduced by 36%–45%, initial efficiency increased to 94.2%–95.3%, key factors include:

[0058] (1) Synergistic passivation of ionic liquid and nano-silica: 0.1%–0.2% ionic liquid in the primary modifier forms a dense surface film with nano-SiO2, reducing the exposure of active sites. Comparative Example 4 (without ionic liquid) showed an increased specific surface area of ​​8.8 m². 2 / g, initial efficiency decreased by 5.2%;

[0059] (2) Carbon nanotube-polymer composite layer protection: The micropores are sealed by a hydroxypropyl methylcellulose / K90 / carbon nanotube composite layer with a secondary modifier. Comparative Example 7 (without secondary modifier) ​​has a specific surface area of ​​12.0 m². 2 / g, initial efficiency drops to 85.0%;

[0060] (3) Silane coupling agent-alumina sol coating: The tertiary modifier KH-550 / KH-792 coupling agent forms a continuous coating layer with activated alumina (Comparative Example 9, without the tertiary modifier, has a specific surface area of ​​11.0 m²). 2 / g), reducing electrolyte side reactions.

[0061] IV. Process synergy of the pulverization process of this invention:

[0062] (1) Comparative Example 5 (without primary modification): tap density plummeted to 0.65 g / cm³ 3 The initial efficiency was 87.3%, demonstrating the fundamental role of the modifier in the primary crushing stage for subsequent processes.

[0063] (2) Comparative Example 7 (without secondary modification): the particle size distribution deteriorated (Span = 1.60) and the specific surface area increased sharply, showing the key role of secondary fine crushing modification in the control of particle morphology;

[0064] (3) Comparative Example 10 (tertiary spheroidization omitted): D 50 The particle size increased to 12.5 μm and Span = 1.70, indicating the decisive influence of roller milling and ultrasonic atomization modification on the final product performance. Detailed Implementation

[0065] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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. Unless otherwise specified, the raw materials, reagents or devices used in the following embodiments can be obtained from conventional commercial channels or by existing known methods.

[0066] Example 1

[0067] Preparation of primary modifier:

[0068] First, the primary modifier consists of the following raw materials by mass percentage:

[0069] Nano-silica (particle size 20nm, purity 99.8%) 0.8%;

[0070] Sodium polyacrylate (weight average molecular weight 2100) 0.3%;

[0071] Dispersant (BYK-180) 0.4%;

[0072] 0.1% of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt (purity 99%);

[0073] The remainder is deionized water.

[0074] Then, the primary modifier is prepared by the following steps:

[0075] Weigh each raw material according to the mass percentage. After vacuum drying the nano-silica at 80℃ for 4 hours, it is mixed with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in an ultrasonic cell disruptor (power 600W) for 20 minutes to form a pre-dispersed colloid. Then, the dispersant is mixed with deionized water at 45℃ under constant temperature stirring (speed 800rpm) to form a transparent solution. The pre-dispersed colloid is poured into the transparent solution and centrifugal shear force of 3000Gs is applied simultaneously for 15 minutes. Sodium polyacrylate is then added to it and stirred and matured under nitrogen protection for 2 hours to obtain the primary modifier.

[0076] Example 2

[0077] Preparation of primary modifier:

[0078] First, the primary modifier consists of the following raw materials by mass percentage:

[0079] Nano-silica (particle size 20nm, purity 99.8%) 0.9%;

[0080] Sodium polyacrylate (weight average molecular weight 2100) 0.35%;

[0081] Dispersant (BYK-180) 0.45%;

[0082] 0.2% of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt (purity 99%);

[0083] The remainder is deionized water.

[0084] Then, the primary modifier is prepared by the following steps:

[0085] Weigh each raw material according to the mass percentage. After vacuum drying the nano-silica at 80℃ for 5 hours, it is mixed with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in an ultrasonic cell disruptor (power 600W) for 30 minutes to form a pre-dispersed colloid. Then, the dispersant is mixed with deionized water at 45℃ under constant temperature stirring (speed 800rpm) to form a transparent solution. The pre-dispersed colloid is poured into the transparent solution and centrifugal shear force of 3000Gs is applied simultaneously for 20 minutes. Sodium polyacrylate is then added to it and stirred and matured under nitrogen protection for 2 hours to obtain the primary modifier.

[0086] Example 3

[0087] Preparation of primary modifier:

[0088] First, the primary modifier consists of the following raw materials by mass percentage:

[0089] Nano-silica (particle size 20nm, purity 99.8%) 1.0%;

[0090] Sodium polyacrylate (weight average molecular weight 2100) 0.4%;

[0091] Dispersant (BYK-180) 0.5%;

[0092] 0.2% of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt (purity 99%);

[0093] The remainder is deionized water.

[0094] Then, the primary modifier is prepared by the following steps:

[0095] Weigh each raw material according to the mass percentage. After vacuum drying the nano-silica at 100℃ for 5h, it is mixed with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in an ultrasonic cell disruptor (power 600W) for 30min to form a pre-dispersed colloid. Then, the dispersant is mixed with deionized water at 45℃ under constant temperature stirring (speed 800rpm) to form a transparent solution. The pre-dispersed colloid is poured into the transparent solution and centrifugal shear force of 3000Gs is applied simultaneously for 20min. Sodium polyacrylate is then added and stirred and matured under nitrogen protection for 2h to obtain the primary modifier.

[0096] Comparative Example 1

[0097] Comparative Example 1 served as the control group for Example 3, except that the raw material 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in Example 3 was replaced with deionized water, i.e., the raw material 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was removed, as detailed below:

[0098] Preparation of primary modifier:

[0099] First, the primary modifier consists of the following raw materials by mass percentage:

[0100] Nano-silica (particle size 20nm, purity 99.8%) 1.0%;

[0101] Sodium polyacrylate (weight average molecular weight 2100) 0.4%;

[0102] Dispersant (BYK-180) 0.5%;

[0103] The remainder is deionized water.

[0104] Then, the primary modifier is prepared by the following steps:

[0105] Weigh each raw material according to the mass percentage, and dry the nano-silica under vacuum at 100℃ for 5 hours to obtain dried nano-silica; then mix the dispersant and deionized water at a constant temperature of 45℃ with stirring (800 rpm) to form a transparent solution; pour the dried nano-silica into the transparent solution, and simultaneously apply a centrifugal shear force of 3000 Gs for 20 minutes, then add sodium polyacrylate, and stir and mature under nitrogen protection for 2 hours to obtain the primary modifier.

[0106] Example 4

[0107] Preparation of secondary modifiers:

[0108] First, the secondary modifier comprises the following raw materials by weight:

[0109] 6 parts of hydroxypropyl methylcellulose (viscosity 4000 mPa·s);

[0110] Three parts of polyvinylpyrrolidone (K90, number average molecular weight 360,000);

[0111] 1 part of sodium tetraborate (analytical grade);

[0112] Five parts of hydroxylated multi-walled carbon nanotubes (outer diameter 5-15 nm, length 10-50 μm);

[0113] 150 parts of anhydrous ethanol;

[0114] 50 parts deionized water.

[0115] Then, the secondary modifier is prepared by the following steps:

[0116] Weigh out each raw material according to the mass fraction, add deionized water to anhydrous ethanol with stirring, then add hydroxypropyl methylcellulose and polyvinylpyrrolidone. Heat the system to 45℃ and swell at 500 rpm for 3 hours. After completion, a transparent colloid is obtained. Add sodium tetraborate to the transparent colloid with stirring, and adjust the pH of the system to 9.2 with 0.1 mol / L NaOH solution. After completion, purge the system with nitrogen to replace the air, and finally purge with nitrogen to maintain 0.3 MPa. After completion, heat the system to 55℃ and perform a dynamic cross-linking reaction at a constant temperature for 4 hours. Then add hydroxylated multi-walled carbon nanotubes with stirring, and then cycle the mixture 15 times under 120 MPa pressure using a high-pressure homogenizer, with a 30-second interval between each cycle for cooling. After completion, a secondary modifier is obtained.

[0117] Example 5

[0118] Preparation of secondary modifiers:

[0119] First, the secondary modifier comprises the following raw materials by weight:

[0120] 8 parts of hydroxypropyl methylcellulose (viscosity 4000 mPa·s);

[0121] Four parts of polyvinylpyrrolidone (K90, number average molecular weight 360,000);

[0122] Two portions of sodium tetraborate (analytical grade);

[0123] Six parts of hydroxylated multi-walled carbon nanotubes (outer diameter 5-15 nm, length 10-50 μm);

[0124] 150 parts of anhydrous ethanol;

[0125] 50 parts deionized water.

[0126] Then, the secondary modifier is prepared by the following steps:

[0127] Weigh out each raw material according to the mass fraction, add deionized water to anhydrous ethanol with stirring, then add hydroxypropyl methylcellulose and polyvinylpyrrolidone. Heat the system to 50℃ and swell at 500 rpm for 5 hours. After completion, a transparent colloid is obtained. Add sodium tetraborate to the transparent colloid with stirring, and adjust the pH of the system to 9.4 with 0.1 mol / L NaOH solution. After completion, purge the system with nitrogen to replace the air, and finally purge with nitrogen to maintain 0.4 MPa. After completion, heat the system to 55℃ and perform a dynamic cross-linking reaction at a constant temperature for 5 hours. Then add hydroxylated multi-walled carbon nanotubes with stirring, and then cycle the mixture 15 times under 120 MPa pressure using a high-pressure homogenizer, with a 30-second interval between each cycle for cooling. After completion, a secondary modifier is obtained.

[0128] Example 6

[0129] Preparation of secondary modifiers:

[0130] First, the secondary modifier comprises the following raw materials by weight:

[0131] 10 parts of hydroxypropyl methylcellulose (viscosity 4000 mPa·s);

[0132] Five parts of polyvinylpyrrolidone (K90, number average molecular weight 360,000);

[0133] Two portions of sodium tetraborate (analytical grade);

[0134] Eight portions of hydroxylated multi-walled carbon nanotubes (outer diameter 5–15 nm, length 10–50 μm);

[0135] 150 parts of anhydrous ethanol;

[0136] 50 parts deionized water.

[0137] Then, the secondary modifier is prepared by the following steps:

[0138] Weigh out each raw material according to the specified mass fractions, add deionized water to anhydrous ethanol with stirring, then add hydroxypropyl methylcellulose and polyvinylpyrrolidone. Heat the system to 50°C and maintain the temperature at 500 rpm for 5 hours to swell. After completion, a transparent colloid is obtained. Add sodium tetraborate to the transparent colloid with stirring, and adjust the pH of the system to 9.5 with 0.1 mol / L NaOH solution. After completion, purge the system with nitrogen to replace the air, and finally purge with nitrogen to maintain 0.5 MPa. After completion, heat the system to 60°C and maintain the temperature for dynamic cross-linking reaction for 5 hours. Then add hydroxylated multi-walled carbon nanotubes with stirring, and then cycle the mixture 15 times under 120 MPa pressure using a high-pressure homogenizer, with a 30-second interval between each cycle for cooling. After completion, a secondary modifier is obtained.

[0139] Comparative Example 2

[0140] Comparative Example 2 served as the control group for Example 6, except that the hydroxylated multi-walled carbon nanotubes used in Example 6 were removed, as detailed below:

[0141] Preparation of secondary modifiers:

[0142] First, the secondary modifier comprises the following raw materials by weight:

[0143] 10 parts of hydroxypropyl methylcellulose (viscosity 4000 mPa·s);

[0144] Five parts of polyvinylpyrrolidone (K90, number average molecular weight 360,000);

[0145] Two portions of sodium tetraborate (analytical grade);

[0146] 150 parts of anhydrous ethanol;

[0147] 50 parts deionized water.

[0148] Then, the secondary modifier is prepared by the following steps:

[0149] Weigh out each raw material according to the specified mass fractions, add deionized water to anhydrous ethanol with stirring, then add hydroxypropyl methylcellulose and polyvinylpyrrolidone. Heat the system to 50°C and maintain the temperature at 500 rpm for 5 hours to swell. After completion, a transparent colloid is obtained. Add sodium tetraborate to the transparent colloid with stirring, and adjust the pH of the system to 9.5 with 0.1 mol / L NaOH solution. After completion, purge the system with nitrogen to replace the air, and finally purge with nitrogen to maintain 0.5 MPa. After completion, heat the system to 60°C and maintain the temperature for dynamic crosslinking reaction for 5 hours. Then, use a high-pressure homogenizer to cycle the reaction 15 times at 120 MPa, with a 30-second cooling interval between each cycle. After completion, a secondary modifier is obtained.

[0150] Example 7

[0151] Preparation of tertiary modifiers:

[0152] First, the tertiary modifier comprises the following raw materials by weight:

[0153] 15 parts of silane coupling agent KH-550;

[0154] 10 parts of silane coupling agent KH-792;

[0155] 1.2 parts of alumina sol (20% solid content);

[0156] 0.05 parts of polyethylene glycol (weight average molecular weight 6000);

[0157] 200 portions of deionized water.

[0158] Then, the tertiary modifier is prepared by the following steps:

[0159] Weigh each raw material according to the mass fraction. Add silane coupling agent KH-550 and silane coupling agent KH-792 to deionized water and stir. Then add glacial acetic acid to adjust the pH of the system to 4.4. After completion, stir at 200 rpm for 4 hours to hydrolyze and obtain a pre-hydrolyzed silane solution. Then place the alumina sol in a plasma reaction chamber, introduce an Ar / H2 mixed gas (volume ratio 9:1) at a flow rate of 50 sccm, apply a radio frequency power of 200 W (13.56 MHz) for 25 min, and obtain an activated alumina sol. Mix the pre-hydrolyzed silane solution and the activated alumina sol and heat to 60℃. Stir at a constant temperature for 15 min, then add polyethylene glycol and sonicate at 40 kHz frequency and 800 W power for 20 min to obtain a tertiary modifier.

[0160] Example 8

[0161] Preparation of tertiary modifiers:

[0162] First, the tertiary modifier comprises the following raw materials by weight:

[0163] 18 parts of silane coupling agent KH-550;

[0164] 12 parts of silane coupling agent KH-792;

[0165] 1.5 parts of alumina sol (20% solid content);

[0166] 0.08 parts of polyethylene glycol (weight average molecular weight 6000);

[0167] 200 portions of deionized water.

[0168] Then, the tertiary modifier is prepared by the following steps:

[0169] Weigh each raw material according to the mass fraction. Add silane coupling agent KH-550 and silane coupling agent KH-792 to deionized water with stirring. Then add glacial acetic acid to adjust the pH of the system to 4.5. After completion, stir at 200 rpm for 5 hours to hydrolyze and obtain a pre-hydrolyzed silane solution. Then place the alumina sol in a plasma reaction chamber, introduce an Ar / H2 mixed gas (volume ratio 9:1) at a flow rate of 50 sccm, apply a radio frequency power of 200 W (13.56 MHz) for 30 minutes, and obtain an activated alumina sol. Mix the pre-hydrolyzed silane solution and the activated alumina sol, heat to 60℃, stir at a constant temperature for 20 minutes, then add polyethylene glycol with stirring. Sonicate at 40 kHz frequency and 800 W power for 30 minutes to obtain a tertiary modifier.

[0170] Example 9

[0171] Preparation of tertiary modifiers:

[0172] First, the tertiary modifier comprises the following raw materials by weight:

[0173] 20 parts of silane coupling agent KH-550;

[0174] 12 parts of silane coupling agent KH-792;

[0175] 1.5 parts of alumina sol (20% solid content);

[0176] 0.1 parts of polyethylene glycol (weight average molecular weight 6000);

[0177] 200 portions of deionized water.

[0178] Then, the tertiary modifier is prepared by the following steps:

[0179] Weigh each raw material according to the mass fraction. Add silane coupling agent KH-550 and silane coupling agent KH-792 to deionized water with stirring. Then add glacial acetic acid to adjust the pH of the system to 4.5. After completion, stir at 200 rpm for 5 hours to hydrolyze and obtain a pre-hydrolyzed silane solution. Then place the alumina sol in a plasma reaction chamber, introduce an Ar / H2 mixed gas (volume ratio 9:1) at a flow rate of 50 sccm, apply a radio frequency power of 200 W (13.56 MHz) for 30 minutes, and obtain an activated alumina sol. Mix the pre-hydrolyzed silane solution and the activated alumina sol, heat to 65℃, stir at a constant temperature for 20 minutes, then add polyethylene glycol with stirring. Sonicate at 40 kHz frequency and 800 W power for 30 minutes to obtain a tertiary modifier.

[0180] Comparative Example 3

[0181] Comparative Example 3 served as the control group for Example 9, except that the activation process of the alumina sol in Example 9 was removed, as detailed below:

[0182] Preparation of tertiary modifiers:

[0183] First, the tertiary modifier comprises the following raw materials by weight:

[0184] 20 parts of silane coupling agent KH-550;

[0185] 12 parts of silane coupling agent KH-792;

[0186] 1.5 parts of alumina sol (20% solid content);

[0187] 0.1 parts of polyethylene glycol (weight average molecular weight 6000);

[0188] 200 portions of deionized water.

[0189] Then, the tertiary modifier is prepared by the following steps:

[0190] Weigh each raw material according to the mass fraction, add silane coupling agent KH-550 and silane coupling agent KH-792 to deionized water and stir. Then add glacial acetic acid to adjust the pH of the system to 4.5. After completion, stir at 200 rpm for 5 hours to hydrolyze and obtain a pre-hydrolyzed silane solution. Mix the pre-hydrolyzed silane solution and alumina sol and heat to 65℃. Stir at a constant temperature for 20 minutes. Then add polyethylene glycol and sonicate at 40 kHz frequency and 800 W power for 30 minutes to obtain a tertiary modifier.

[0191] Example 10

[0192] A pulverization process for derived biomass hard carbon materials includes the following steps:

[0193] S1. Hard carbon precursor pretreatment: Coconut shell-derived hard carbon blocks (with a fixed average carbon content of 92.5%) were placed in a 100°C forced-air drying oven and dried until the moisture content was ≤0.5% to obtain dried coconut shell-derived hard carbon blocks. The moisture content of the dried coconut shell-derived hard carbon blocks in this embodiment was 0.5% after testing.

[0194] S2. Primary coarse crushing and atomization treatment: The dried coconut shell-derived hard carbon blocks are subjected to primary crushing (crusher). At the same time as primary crushing, the primary modifier prepared in Example 1 is sprayed. The primary modifier prepared in Example 1 is sprayed by high-pressure atomization spray (pressure 0.3MPa, flow rate 5L / min). After completion, coarse crushed modified particles with a particle size of 3mm are obtained.

[0195] S3. Secondary Fine Crushing and Atomization Treatment: The coarsely crushed modified particles are subjected to secondary fine crushing (using a pulverizer) under an argon atmosphere (purity ≥99.9%). Simultaneously, the secondary modifier prepared in Example 4 is sprayed onto the particles. The spraying method for the secondary modifier prepared in Example 4 is dual-fluid atomization spraying (compressed air pressure 0.4 MPa, flow rate 3 L / min). After completion, D is obtained. 50 Finely crushed modified particles with a particle size of 15 μm;

[0196] S4. Three-stage shaping and atomization treatment: The finely crushed modified particles are spheroidized by roller milling (roller mill). Simultaneously, the three-stage modifier prepared in Example 7 is sprayed onto the particles. The spraying method for the three-stage modifier prepared in Example 7 is ultrasonic atomization (frequency 28kHz, flow rate 2L / min). After completion, D is obtained. 50 Spherical modified particles with a particle size of 10 μm;

[0197] S5. Post-processing: The spherical modified particles are flash-dried in a nitrogen atmosphere for 2 minutes. After drying, they are cooled to room temperature to obtain powder. The powder is placed in a vacuum mixer (50 rpm) and 0.1 wt% magnesium stearate is added. The mixture is mixed for 10 minutes to obtain biomass hard carbon powder. The biomass hard carbon powder is packed into an aluminum foil bag, filled with argon gas and sealed to obtain the product-derived biomass hard carbon material.

[0198] Example 11

[0199] A pulverization process for derived biomass hard carbon materials includes the following steps:

[0200] S1. Hard carbon precursor pretreatment: Coconut shell-derived hard carbon blocks (with a fixed average carbon content of 92.5%) were placed in a 100°C forced-air drying oven and dried until the moisture content was ≤0.5% to obtain dried coconut shell-derived hard carbon blocks. The moisture content of the dried coconut shell-derived hard carbon blocks in this embodiment was 0.2% after testing.

[0201] S2. Primary coarse crushing and atomization treatment: The dried coconut shell-derived hard carbon blocks are subjected to primary crushing (crusher). At the same time as primary crushing, the primary modifier prepared in Example 2 is sprayed. The primary modifier prepared in Example 2 is sprayed by high-pressure atomization spray (pressure 0.4MPa, flow rate 5L / min). After completion, coarse crushed modified particles with a particle size of 1mm are obtained.

[0202] S3. Secondary Fine Crushing and Atomization Treatment: The coarsely crushed modified particles are subjected to secondary fine crushing (using a pulverizer) under an argon atmosphere (purity ≥99.9%). Simultaneously, the secondary modifier prepared in Example 5 is sprayed onto the particles. The spraying method for the secondary modifier prepared in Example 5 is dual-fluid atomization spraying (compressed air pressure 0.5 MPa, flow rate 3 L / min). After completion, D is obtained. 50 Finely crushed modified particles with a particle size of 15 μm;

[0203] S4. Three-stage shaping and atomization treatment: The finely crushed modified particles are spheroidized by roller milling (roller mill). Simultaneously, the three-stage modifier prepared in Example 8 is sprayed onto the particles. The spraying method for the three-stage modifier prepared in Example 8 is ultrasonic atomization (frequency 28kHz, flow rate 2L / min). After completion, D is obtained. 50 Spherical modified particles with a particle size of 10 μm;

[0204] S5. Post-processing: The spherical modified particles are flash-dried in a nitrogen atmosphere for 3 minutes. After drying, they are cooled to room temperature to obtain powder. The powder is placed in a vacuum mixer (50 rpm) and 0.1 wt% magnesium stearate is added. The mixture is mixed for 10 minutes to obtain biomass hard carbon powder. The biomass hard carbon powder is packed into an aluminum foil bag, filled with argon gas and sealed to obtain the product-derived biomass hard carbon material.

[0205] Example 12

[0206] A pulverization process for derived biomass hard carbon materials includes the following steps:

[0207] S1. Hard carbon precursor pretreatment: Coconut shell-derived hard carbon blocks (with a fixed average carbon content of 92.5%) were placed in a 105°C forced-air drying oven and dried until the moisture content was ≤0.5% to obtain dried coconut shell-derived hard carbon blocks. The moisture content of the dried coconut shell-derived hard carbon blocks in this embodiment was 0.2% after testing.

[0208] S2. Primary coarse crushing and atomization treatment: The dried coconut shell-derived hard carbon blocks are subjected to primary crushing (crusher). At the same time as primary crushing, the primary modifier prepared in Example 3 is sprayed. The primary modifier prepared in Example 3 is sprayed by high-pressure atomization spray (pressure 0.5MPa, flow rate 5L / min). After completion, coarse crushed modified particles with a particle size of 1mm are obtained.

[0209] S3. Secondary Fine Crushing and Atomization Treatment: The coarsely crushed modified particles are subjected to secondary fine crushing (using a pulverizer) under an argon atmosphere (purity ≥99.9%). Simultaneously, the secondary modifier prepared in Example 6 is sprayed onto the particles. The spraying method for the secondary modifier prepared in Example 6 is dual-fluid atomization spraying (compressed air pressure 0.5 MPa, flow rate 3 L / min). After completion, D is obtained. 50 Finely crushed modified particles with a particle size of 15 μm;

[0210] S4. Three-stage shaping and atomization treatment: The finely crushed modified particles are spheroidized by roller milling (roller mill). Simultaneously, the three-stage modifier prepared in Example 9 is sprayed onto the particles. The spraying method for the three-stage modifier prepared in Example 9 is ultrasonic atomization (frequency 28kHz, flow rate 2L / min). After completion, D is obtained. 50 Spherical modified particles with a particle size of 10 μm;

[0211] S5. Post-processing: The spherical modified particles are flash-dried in a nitrogen atmosphere for 3 minutes. After drying, they are cooled to room temperature to obtain powder. The powder is placed in a vacuum mixer (50 rpm) and 0.1 wt% magnesium stearate is added. The mixture is mixed for 10 minutes to obtain biomass hard carbon powder. The biomass hard carbon powder is packed into an aluminum foil bag, filled with argon gas and sealed to obtain the product-derived biomass hard carbon material.

[0212] Comparative Example 4

[0213] Comparative Example 4 served as the control group for Example 12. The primary modifier prepared in Example 3 in S2 of Example 12 was replaced with the primary modifier prepared in Comparative Example 1. The remaining raw materials, raw material amounts, process parameters, and process steps remained consistent with those in Example 12, and the derived biomass hard carbon material was finally obtained.

[0214] Comparative Example 5

[0215] Comparative Example 5 served as the control group for Example 12. The primary modifier prepared in Example 3 in S2 of Example 12 was replaced with deionized water. The remaining raw materials, raw material amounts, process parameters, and process steps remained consistent with those in Example 12, and the derived biomass hard carbon material was finally obtained.

[0216] Comparative Example 6

[0217] Comparative Example 6 served as the control group for Example 12. The secondary modifier prepared in Example 6 in S3 of Example 12 was replaced with the secondary modifier prepared in Comparative Example 2. The remaining raw materials, raw material amounts, process parameters, and process steps remained consistent with those in Example 12, and the derived biomass hard carbon material was finally obtained.

[0218] Comparative Example 7

[0219] Comparative Example 7 served as the control group for Example 12. The secondary modifier prepared in Example 6 in S3 of Example 12 was replaced with deionized water. The remaining raw materials, raw material amounts, process parameters, and process steps remained consistent with those in Example 12, and the derived biomass hard carbon material was finally obtained.

[0220] Comparative Example 8

[0221] Comparative Example 8 served as the control group for Example 12. The tertiary modifier prepared in Example 9 in S4 of Example 12 was replaced with the tertiary modifier prepared in Comparative Example 3. The remaining raw materials, raw material amounts, process parameters, and process steps remained consistent with those in Example 12, and the derived biomass hard carbon material was finally obtained.

[0222] Comparative Example 9

[0223] Comparative Example 9 served as the control group for Example 12. The tertiary modifier prepared in Example 9 in S4 of Example 12 was replaced with deionized water. The remaining raw materials, raw material amounts, process parameters, and process steps remained consistent with those in Example 12, and the derived biomass hard carbon material was finally obtained.

[0224] Comparative Example 10

[0225] Comparative Example 10 serves as the control group for Example 12, with the three-stage shaping and atomization process of S4 in Example 12 removed, as detailed below:

[0226] A pulverization process for derived biomass hard carbon materials includes the following steps:

[0227] S1. Hard carbon precursor pretreatment: Coconut shell-derived hard carbon blocks (with a fixed average carbon content of 92.5%) were placed in a 105°C forced-air drying oven and dried until the moisture content was ≤0.5% to obtain dried coconut shell-derived hard carbon blocks. The moisture content of the dried coconut shell-derived hard carbon blocks in this embodiment was 0.2% after testing.

[0228] S2. Primary coarse crushing and atomization treatment: The dried coconut shell-derived hard carbon blocks are subjected to primary crushing (crusher). At the same time as primary crushing, the primary modifier prepared in Example 3 is sprayed. The primary modifier prepared in Example 3 is sprayed by high-pressure atomization spray (pressure 0.5MPa, flow rate 5L / min). After completion, coarse crushed modified particles with a particle size of 1mm are obtained.

[0229] S3. Secondary Fine Crushing and Atomization Treatment: The coarsely crushed modified particles are subjected to secondary fine crushing (using a pulverizer) under an argon atmosphere (purity ≥99.9%). Simultaneously, the secondary modifier prepared in Example 6 is sprayed onto the particles. The spraying method for the secondary modifier prepared in Example 6 is dual-fluid atomization spraying (compressed air pressure 0.5 MPa, flow rate 3 L / min). After completion, D is obtained. 50 Finely crushed modified particles with a particle size of 10 μm;

[0230] S4. Post-processing: The finely crushed modified particles are flash-dried in a nitrogen atmosphere for 3 minutes. After drying, they are cooled to room temperature to obtain powder. The powder is placed in a vacuum mixer (50 rpm) and 0.1 wt% magnesium stearate is added. The mixture is mixed for 10 minutes to obtain biomass hard carbon powder. The biomass hard carbon powder is packed into an aluminum foil bag, filled with argon gas and sealed to obtain the product-derived biomass hard carbon material.

[0231] Test Example 1

[0232] The performance of the derived biomass hard carbon materials prepared in Examples 10-12 and Comparative Examples 4-10 was tested. The performance test results are shown in Table 1 and Table 2.

[0233] Table 1 Test Standards

[0234]

[0235] Table 2 Test Results

[0236]

[0237] As can be seen from Table 2, the technical solutions of Examples 10 to 12 of this invention achieve the following through the synergistic effect of a three-stage gradient modifier (containing ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, hydroxylated multi-walled carbon nanotubes, and activated alumina sol) and a progressive pulverization process:

[0238] (1) Tap density increase: 0.83~0.89 g / cm³ 3 ;

[0239] (2) Particle size distribution optimization: Span value 1.06~1.15;

[0240] (3) Breakthrough in electrochemical performance: initial efficiency of 94.2% to 95.3%.

[0241] Meanwhile, data from Comparative Examples 4 to 10 and Example 12 show that the absence of any one of the three processes or modifiers leads to a sharp drop in performance, proving that none of the three processes can be omitted.

[0242] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0243] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pulverization process for derived biomass hard carbon materials, characterized in that, Includes the following steps: S1. After drying the coconut shell-derived hard carbon blocks, they are subjected to primary crushing and primary modifier is sprayed at the same time. After completion, coarsely crushed modified particles with a particle size of 1-3 mm are obtained. S2. The coarsely crushed modified particles are subjected to secondary fine crushing under an argon atmosphere, while a secondary modifier is sprayed on. After completion, D is obtained. 50 Finely crushed modified particles with a particle size of 15 μm; S3. The finely crushed modified particles are then ballized by roller milling, while a three-stage modifier is sprayed on. After completion, D is obtained. 50 Spherical modified particles with a particle size of 10 μm; S4. Flash-dry the spherical modified particles in a nitrogen atmosphere for 2-3 minutes. After completion, cool to room temperature and add 0.1 wt% magnesium stearate. Mix for 10 minutes to obtain the derived biomass hard carbon material. The primary modifier is composed of the following raw materials by mass percentage: nano silica 0.8%–1.0%; sodium polyacrylate 0.3%–0.4%; dispersant BYK-180 0.4%–0.5%; 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt 0.1%–0.2%; the balance being deionized water; The secondary modifier comprises the following raw materials in parts by weight: 6-10 parts hydroxypropyl methylcellulose; 3-5 parts polyvinylpyrrolidone K90; 1-2 parts sodium tetraborate; 5-8 parts hydroxylated multi-walled carbon nanotubes; 150 parts anhydrous ethanol; and 50 parts deionized water. The tertiary modifier comprises the following raw materials in parts by weight: 15-20 parts of silane coupling agent KH-550; 10-12 parts of silane coupling agent KH-792; 1.2-1.5 parts of alumina sol; 0.05-0.1 parts of polyethylene glycol; and 200 parts of deionized water. The alumina sol is an activated alumina sol, and the activation treatment includes the following steps: The alumina sol was placed in a plasma reaction chamber, and an Ar / H2 mixed gas was introduced at a volume ratio of 9:1 at a flow rate of 50 sccm. A radio frequency power of 200 W was applied, and the treatment time was 25–30 min. After the treatment was completed, activated alumina sol was obtained.

2. The pulverization process for a derived biomass hard carbon material according to claim 1, characterized in that, The primary modifier is sprayed using high-pressure atomization spraying, with a pressure of 0.3–0.5 MPa and a flow rate of 5 L / min; the secondary modifier is sprayed using two-fluid atomization spraying, with a compressed air pressure of 0.4–0.5 MPa and a flow rate of 3 L / min; and the tertiary modifier is sprayed using ultrasonic atomization, with a frequency of 28 kHz and a flow rate of 2 L / min.

3. The pulverization process for a derived biomass hard carbon material according to claim 1, characterized in that, The primary modifier is prepared by the following steps: Weigh each raw material according to the mass percentage. After vacuum drying the nano-silica at 80-100℃ for 4-5 hours, it is mixed with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in an ultrasonic cell disruptor for 20-30 minutes to form a pre-dispersed colloid. Then, the dispersant BYK-180 is mixed with deionized water at a constant temperature of 45℃ with stirring to form a transparent solution. The pre-dispersed colloid is poured into the transparent solution and centrifugally sheared at 3000Gs for 15-20 minutes. Sodium polyacrylate is then added and stirred and matured under nitrogen protection for 2 hours to obtain the primary modifier.

4. The pulverization process for a derivative biomass hard carbon material according to claim 1, characterized in that, The secondary modifier is prepared by the following steps: Weigh each raw material according to the specified mass fractions. Add deionized water to anhydrous ethanol and then add hydroxypropyl methylcellulose and polyvinylpyrrolidone K90. Heat the system to 45–50°C and maintain the temperature for 3–5 hours to allow swelling. After this process, a transparent colloid is obtained. Add sodium tetraborate to the transparent colloid and adjust the pH of the system to 9.2–9.

5. Then, purge the system with nitrogen to replace the air. Finally, purge with nitrogen at a pressure of 0.3–0.5 MPa and heat the system to 55–60°C for 4–5 hours. Add hydroxylated multi-walled carbon nanotubes and then purge the system using a high-pressure homogenizer at 120 MPa for 15 cycles, with a 30-second cooling interval between each cycle. After this process, a secondary modifier is obtained.

5. The pulverization process for a derived biomass hard carbon material according to claim 1, characterized in that, The tertiary modifier is prepared by the following steps: Weigh each raw material according to the mass fraction, add silane coupling agent KH-550 and silane coupling agent KH-792 to deionized water and stir, then adjust the pH of the system to 4.4-4.

5. After completion, stir and hydrolyze for 4-5 hours to obtain a pre-hydrolyzed silane solution. The alumina sol is then activated to obtain activated alumina sol. The pre-hydrolyzed silane solution and activated alumina sol are mixed and heated to 60-65°C, stirred at a constant temperature for 15-20 minutes, and then polyethylene glycol is added and ultrasonically treated for 20-30 minutes to obtain a tertiary modifier.

Images