Preparation method and application of pitch-based hard carbon microsphere sodium storage material

Abstract

The application discloses a preparation method and application of pitch-based hard carbon microsphere sodium storage material and belongs to the technical field of electrochemical energy storage. In view of the problems of low residual carbon rate of biomass carbon source, high price of polymer carbon source, complex process, long time consumption, uneven size of obtained material and low sphericity in the preparation of hard carbon microspheres, the pitch raw material is ground, sieved, dried to obtain a solid mixture, and a viscosity reducer is added to heat and stir to obtain a molten mixture. The molten mixture is slowly injected into a high-pressure reaction kettle from the bottom through a porous sieve plate and is heated and stirred to obtain pitch microspheres. A water solution containing a surfactant is poured into the reaction kettle in advance. The pitch microspheres are dried under reduced pressure, are heated to be solidified and crosslinked in an air atmosphere, and are heated to be carbonized in a nitrogen atmosphere to obtain pitch-based hard carbon microsphere sodium storage material. The pitch-based hard carbon microsphere sodium storage material prepared by the application has a diameter of 1-50 microns and a sphericity of greater than 90%, and exhibits excellent sodium storage capacity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical energy storage, and particularly relates to a preparation method and application of a pitch-based hard carbon microsphere sodium storage material. BACKGROUND

[0002] With the rapid development of electric vehicles and various mobile electronic devices, the performance requirements of energy storage devices are becoming higher and higher. Lithium ion batteries have been mass-produced commercially, but the problem of high production cost due to the shortage of lithium resources is difficult to solve. Sodium content is much higher than that of lithium, and the resource is abundant, and the price is lower than that of lithium. Due to the relationship between the same main group, sodium ion batteries and lithium ion batteries have similar characteristics, so they have received more and more attention in the field of large-scale energy storage. The size of sodium ions is larger than the interlayer spacing of graphite, which makes it difficult to apply graphite materials suitable for lithium ion batteries to sodium ion batteries. Therefore, it is particularly important to develop negative electrode materials with high energy density for the development of sodium ion batteries.

[0003] At present, people have found other carbon materials for sodium ion battery negative electrode, such as soft carbon and hard carbon. Hard carbon refers to carbon that is difficult to graphitize, and presents a short-range graphite sheet layer disordered stacking structure, so that its interlayer spacing is much larger than the size of sodium ions, so it has high energy density and excellent rate performance, and has attracted strong attention from researchers. At present, the commonly used carbon precursors are mainly biomass and high molecular materials. Patent CN 115285969A uses the root of legume plants as a carbon precursor, grinds and crushes, and then performs pre-carbonization and high-temperature carbonization to obtain a nitrogen-doped hard carbon material. Patent CN 115207350A uses dry starch and anhydride as a carbon source to perform a dry esterification reaction, forms a structure-stable cross-linked starch through an ester group, and then obtains a hard carbon negative electrode material through low-temperature hydrogen reduction and high-temperature carbonization. Patent CN 112993248 A uses artificial graphite as a carbon source, dissolves a binder in a solvent, then mixes the artificial graphite, and then mixes spherical hard carbon materials and a conductive agent to obtain a mixture, and then performs pyrolysis and high-temperature carbonization on the mixture to obtain a hard carbon material. Biomass carbon precursors generally have the disadvantages of low carbon yield and great seasonal and regional influence on the source, and high molecular materials have the problem of high price, both of which are difficult to be put into large-scale commercial production. Pitch itself is composed of condensed aromatic hydrocarbons, has high carbon content, low price, and large output, and it is of great significance to the sustainable development of our country to synthesize hard carbon energy storage materials with excellent electrochemical performance from pitch.

[0004] The structure design of hard carbon materials can effectively affect their various electrochemical properties. Spherical hard carbon materials exhibit extremely high volumetric energy density and are more suitable for use in electronic device energy storage devices. Patent CN109148865A uses biomass as a carbon source, configures it with hydrochloric acid and the like to form a precursor solution, generates droplets through ultrasonic atomization, and flows into a tubular furnace with inert gas as a carrier. The hard carbon precursor is obtained by pyrolysis under heat. Finally, the hard carbon microspheres are obtained by high-temperature carbonization. Patent CN109148865A uses graphene oxide and a high polymer material as a carbon source, dissolves them in an organic solvent to obtain a composite spray solution, and then sprays and dries and carbonizes to obtain hard carbon composite carbon microsphere negative electrode materials. The preparation process of the above patents is complex and time-consuming, and the obtained hard carbon microspheres are uneven in size and low in sphericity, which seriously affects the volumetric energy density. This problem needs to be solved. SUMMARY

[0005] In view of the problems of low residual carbon rate of biomass carbon sources, high price of high polymer carbon sources, complex preparation process of hard carbon microspheres, long time consumption, uneven size of the obtained materials, and low sphericity, the present application provides a preparation method and application of pitch-based hard carbon microsphere sodium storage material.

[0006] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the present application:

[0007] A preparation method of pitch-based hard carbon microsphere sodium storage material, grinding and sieving the pitch raw material and carbonaceous filler to obtain a solid mixture, then adding a viscosity reducer to the solid mixture by heating and stirring to obtain a molten mixture, pre-filling a water solution containing a surfactant into a high-pressure reaction kettle, then slowly injecting the molten mixture into the high-pressure reaction kettle from the bottom through a perforated screen plate to obtain pitch microspheres by heating and stirring, drying the pitch microspheres under reduced pressure, heating and solidifying and crosslinking in an air atmosphere, and then carbonizing in a nitrogen atmosphere to obtain pitch-based hard carbon microsphere sodium storage material.

[0008] Further, the pitch raw material includes one or a mixture of both of petroleum pitch and coal tar pitch.

[0009] Further, the carbonaceous filler includes one or a mixture of both of coal-based activated carbon, biomass-based activated carbon, carbon black, acetylene black, microcrystalline graphite, and needle coke, and the addition amount is 1-30% of the weight fraction of the raw material pitch.

[0010] Further, the viscosity reducer is an organic solvent, including one of toluene, quinoline, pyridine, 1,2-dichloroethane, and chloroform, and the addition amount is 10-50% of the weight fraction of the raw material pitch.

[0011] Further, the surface active agent comprises one of polyvinyl alcohol, polyethylene glycol, stearic acid, sodium dodecyl benzene sulfonate, Span, Tween, and the adding amount is 1-10% of the mass fraction of the aqueous solution; the adding amount of the aqueous solution containing the surface active agent is 2-10 times of the volume of the mixture in the kettle.

[0012] Further, the porous sieve plate for grinding and screening the asphalt raw material and the carbonaceous filler is made of stainless steel and has a mesh number of 200-500 meshes.

[0013] Further, the temperature of the melting and mixing is higher than the softening point of the asphalt by 10-100 DEG C, the stirring speed is 100-500 r / min, and the melting and mixing time is 1-10 h.

[0014] Further, the heating temperature in the high-pressure reaction kettle is 100-300 DEG C, the stirring speed is 300-1000 r / min, and the reaction time is 2-10 h.

[0015] Further, the temperature of the reduced-pressure drying is 50-200 DEG C, the temperature of the heating for curing and cross-linking in the air atmosphere is 200-500 DEG C, and the temperature of the heating for carbonization in the nitrogen atmosphere is 800-1500 DEG C.

[0016] The asphalt-based hard carbon micron sphere sodium storage material prepared by the method can be used for a sodium ion battery.

[0017] Compared with the prior art, the method has the following advantages:

[0018] 1. The method uses low-cost asphalt and carbonaceous filler as raw materials, and adopts a melting injection mode to form balls in water, so that the ball forming process is simple and easy to operate, and is suitable for industrial production.

[0019] 2. The method adopts a viscosity reducer strategy, which can reduce the viscosity of the material, facilitate the early melting injection, and leave a channel for the inward diffusion of oxygen after being removed, thereby accelerating the curing reaction of the asphalt microspheres.

[0020] 3. The asphalt-based hard carbon micron sphere sodium storage material prepared by the method has a diameter of 1-50 microns and a sphericity of greater than 90%, and exhibits excellent sodium storage capacity. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is an appearance morphology of the asphalt-based hard carbon micron sphere sodium storage material of the method;

[0022] Figure 2 The figure is a sodium storage rate performance of the method;

[0023] Figure 3Figure for sodium storage cycle performance of the present application. DETAILED DESCRIPTION

[0024] Example 1

[0025] The petroleum pitch and the coal-based activated carbon were fully ground to 200 mesh, and the coal-based activated carbon was added in an amount of 1% by weight fraction of the petroleum pitch, and then the solid mixture and toluene were placed in a high-pressure reaction kettle for continued heating and stirring to melt and mix, toluene was added in an amount of 10% by weight fraction of the petroleum pitch, the melting and mixing temperature was 10°C higher than the softening point of the pitch, the stirring rate was 100 r / min, and the melting and mixing time was 1 h, to obtain a melt mixture. The above melt mixture was slowly injected from the bottom into another high-pressure reaction kettle by using a plunger pump, and a water solution containing polyvinyl alcohol was poured into the reaction kettle in advance, the polyvinyl alcohol was added in an amount of 1% by mass fraction of the water solution, and the water solution containing polyvinyl alcohol was added in an amount of 2 times the volume of the mixture in the kettle, and then heating and stirring were performed to disperse it into balls, the heating temperature was 100°C, the stirring rate was 300 r / min, and the reaction time was 2 h, and after the end, the pitch microspheres were obtained by washing the precipitate with water. The pitch microspheres obtained were dried under reduced pressure at a temperature of 100°C to remove toluene and part of the light components, and the dried pitch microspheres were slowly heated to 400°C in an air atmosphere for solidification and crosslinking, and then heated to 1200°C in a nitrogen atmosphere for carbonization, to obtain pitch-based hard carbon microsphere sodium storage material. The surface morphology of the product is shown in FIG. 1, which presents carbon balls with a diameter of about 2 microns, and the shape and size are uniform, the distribution is uniform, and the carbon yield is 57%. Figure 1

[0026] To test its electrochemical performance, the pitch-based hard carbon microsphere material prepared was used as the active material. The active material: acetylene black: polyvinylidene fluoride was ground and mixed at a ratio of 90.0:5.0:5.0 for 30 min, then 1 times the mass of deionized water was added, and stirred for 2 h, and the slurry was sieved with a 180 mesh screen before coating, and then coated on a copper foil after stirring uniformly, and then dried at 120°C, and then cut into a circular electrode with a diameter of 8 mm. The assembly of the simulation battery was performed in an Ar atmosphere glove box, metal sodium was used as the counter electrode, 1 mole of NaPF6 was dissolved in 1 L of ethylene carbonate and diethyl carbonate solution with a volume ratio of 1:1 to prepare a button cell, and the electrochemical performance was evaluated by testing. Figure 2 The energy density can still be maintained at 219 mAh / g at a current density of 2C, showing excellent rate performance. Figure 3 The energy density can still be maintained at 207 mAh / g after 150 cycles of charge and discharge, showing excellent cycle stability.

[0027] ​The rest of the examples and comparative examples were prepared according to the same method as example 1 to prepare sodium ion batteries, and the reversible capacity, the first circle coulombic efficiency and the rate performance were tested. The test results of all examples and comparative examples are shown in Table 1.

[0028] Example 2

[0029] The petroleum pitch and the biomass-based activated carbon were fully ground to 300 mesh, and the biomass-based activated carbon was added in an amount of 10% by weight fraction of the petroleum pitch, and then the solid mixture and quinoline were placed in a high-pressure reaction kettle for further heating and stirring to melt and mix. The quinoline was added in an amount of 20% by weight fraction of the petroleum pitch, the melting and mixing temperature was 20°C higher than the softening point of the pitch, the stirring rate was 200 r / min, and the melting and mixing time was 2 h to obtain a melt mixture. The above melt mixture was slowly injected from the bottom into another high-pressure reaction kettle using a plunger pump through a perforated screen plate. The kettle was pre-filled with a polyethylene glycol-containing aqueous solution, and the polyethylene glycol was added in an amount of 3% by mass fraction of the aqueous solution. The polyethylene glycol-containing aqueous solution was added in an amount of 4 times the volume of the mixture in the kettle. Then, heating and stirring were performed to disperse it into balls. The heating temperature was 200°C, the stirring rate was 500 r / min, and the reaction time was 4 h. After the end, the asphalt microspheres were obtained by washing the precipitate with water. The asphalt microspheres were dried under reduced pressure at a temperature of 100°C to remove quinoline and part of the light components. The dried asphalt microspheres were slowly heated to 400°C in an air atmosphere for solidification and crosslinking, and then heated to 1200°C in a nitrogen atmosphere for carbonization to obtain asphalt-based hard carbon micron sphere sodium storage material. The product obtained was a carbon sphere with a diameter of about 6 microns, and the carbon yield was 61%.

[0030] Example 3

[0031] The petroleum pitch and carbon black are fully ground to 400 mesh, and the amount of carbon black added is 20% by weight of the petroleum pitch, then the solid mixture and pyridine are placed in a high-pressure reaction kettle for further heating and stirring to melt and mix, the amount of pyridine added is 30% by weight of the petroleum pitch, the melting and mixing temperature is 40°C higher than the softening point of the pitch, the stirring rate is 300 r / min, and the melting and mixing time is 4 h, to obtain a melt mixture. The melt mixture is slowly injected from the bottom into another high-pressure reaction kettle through a porous screen plate using a plunger pump, and a water solution containing stearic acid is pre-filled in the reaction kettle, the amount of stearic acid added is 5% by mass of the water solution, and the amount of the water solution containing stearic acid added is 6 times the volume of the mixture in the kettle, then heating and stirring are performed to disperse the mixture into balls, the heating temperature is 300°C, the stirring rate is 700 r / min, and the reaction time is 6 h, after which water is used to rinse and precipitate to obtain pitch microspheres. The pitch microspheres obtained are dried under reduced pressure at a temperature of 100°C to remove pyridine and part of the light components, and the dried pitch microspheres are slowly heated to 400°C in an air atmosphere for solidification and crosslinking, then heated to 1200°C in a nitrogen atmosphere for carbonization, to obtain a pitch-based hard carbon micron sphere sodium storage material. The product obtained is a carbon ball with a diameter of about 14 microns, and the carbon yield is 63%.

[0032] Example 4

[0033] The coal tar pitch and acetylene black are fully ground to 500 mesh, and the amount of acetylene black added is 30% by weight of the coal tar pitch, then the solid mixture and 1,2-dichloroethane are placed in a high-pressure reaction kettle for further heating and stirring to melt and mix, the amount of 1,2-dichloroethane added is 40% by weight of the coal tar pitch, the melting and mixing temperature is 60°C higher than the softening point of the pitch, the stirring rate is 400 r / min, and the melting and mixing time is 6 h, to obtain a melt mixture. The melt mixture is slowly injected from the bottom into another high-pressure reaction kettle through a porous screen plate using a plunger pump, and a water solution containing sodium dodecylbenzenesulfonate is pre-filled in the reaction kettle, the amount of sodium dodecylbenzenesulfonate added is 7% by mass of the water solution, and the amount of the water solution containing sodium dodecylbenzenesulfonate added is 8 times the volume of the mixture in the kettle, then heating and stirring are performed to disperse the mixture into balls, the heating temperature is 200°C, the stirring rate is 900 r / min, and the reaction time is 8 h, after which water is used to rinse and precipitate to obtain pitch microspheres. The pitch microspheres obtained are dried under reduced pressure at a temperature of 100°C to remove 1,2-dichloroethane and part of the light components, and the dried pitch microspheres are slowly heated to 400°C in an air atmosphere for solidification and crosslinking, then heated to 1200°C in a nitrogen atmosphere for carbonization, to obtain a pitch-based hard carbon micron sphere sodium storage material. The product obtained is a carbon ball with a diameter of about 24 microns, and the carbon yield is 62%.

[0034] Example 5

[0035] The coal tar pitch and the microcrystalline graphite are fully ground to 400 mesh, and the microcrystalline graphite is added in an amount of 20% by weight of the coal tar pitch, and then the solid mixture and chloroform are placed in a high-pressure reaction kettle for continued heating, stirring, melting and mixing, the chloroform is added in an amount of 50% by weight of the coal tar pitch, the melting and mixing temperature is 80°C higher than the softening point of the pitch, the stirring rate is 500 r / min, and the melting and mixing time is 8 h to obtain a melting and mixing material. The plunger pump is used to slowly inject the melting and mixing material from the bottom into another high-pressure reaction kettle through a porous screen plate, a water solution containing Span is poured into the reaction kettle in advance, the Span is added in an amount of 9% by mass of the water solution, the water solution containing Span is added in an amount of 10 times the volume of the mixture in the kettle, and then heating and stirring are performed to disperse the mixture into balls, the heating temperature is 200°C, the stirring rate is 1000 r / min, and the reaction time is 10 h, and after the end, water is used to wash and precipitate to obtain pitch microspheres. The pitch microspheres are dried at a temperature of 100°C under reduced pressure to remove chloroform and part of the light components, the dried pitch microspheres are slowly heated to 400°C in an air atmosphere for solidification and crosslinking, and then heated to 1200°C in a nitrogen atmosphere for carbonization to obtain pitch-based hard carbon microsphere sodium storage materials. The obtained product is a carbon ball with a diameter of about 31 microns, and the carbon yield is 66%.

[0036] Example 6

[0037] The coal tar pitch and the needle coke are fully ground to 400 mesh, and the needle coke is added in an amount of 20% by weight of the coal tar pitch, and then the solid mixture and chloroform are placed in a high-pressure reaction kettle for continued heating, stirring, melting and mixing, the chloroform is added in an amount of 30% by weight of the coal tar pitch, the melting and mixing temperature is 100°C higher than the softening point of the pitch, the stirring rate is 300 r / min, and the melting and mixing time is 10 h to obtain a melting and mixing material. The plunger pump is used to slowly inject the melting and mixing material from the bottom into another high-pressure reaction kettle through a porous screen plate, a water solution containing Tween is poured into the reaction kettle in advance, the Tween is added in an amount of 10% by mass of the water solution, the water solution containing Tween is added in an amount of 6 times the volume of the mixture in the kettle, and then heating and stirring are performed to disperse the mixture into balls, the heating temperature is 200°C, the stirring rate is 700 r / min, and the reaction time is 6 h, and after the end, water is used to wash and precipitate to obtain pitch microspheres. The pitch microspheres are dried at a temperature of 100°C under reduced pressure to remove chloroform and part of the light components, the dried pitch microspheres are slowly heated to 400°C in an air atmosphere for solidification and crosslinking, and then heated to 1200°C in a nitrogen atmosphere for carbonization to obtain pitch-based hard carbon microsphere sodium storage materials. The obtained product is a carbon ball with a diameter of about 46 microns, and the carbon yield is 67%.

[0038] Example 7

[0039] The petroleum pitch, coal tar pitch, coal-based activated carbon and biomass-based activated carbon are fully ground to 400 mesh, the ratio of petroleum pitch to coal tar pitch is 3:1, the ratio of coal-based activated carbon to biomass-based activated carbon is 3:1, and the amount of carbonaceous filler added accounts for 20% of the weight fraction of pitch, then the solid mixture and chloroform are placed in a high-pressure reaction kettle for further heating, stirring and melting mixing, the amount of chloroform added accounts for 30% of the weight fraction of coal tar pitch, the melting mixing temperature is 60℃ higher than the softening point of pitch, the stirring rate is 300r / min, and the melting mixing time is 6h, to obtain a melting mixture. The above melting mixture is slowly injected from the bottom into another high-pressure reaction kettle by using a plunger pump, and a polyvinyl alcohol-containing aqueous solution is poured into the reaction kettle in advance, the amount of polyvinyl alcohol added accounts for 5% of the mass fraction of the aqueous solution, the amount of polyvinyl alcohol-containing aqueous solution added is 6 times the volume of the mixture in the kettle, then heating and stirring are carried out to disperse it into balls, the heating temperature is 200℃, the stirring rate is 700r / min, and the reaction time is 6h, after which the precipitate is washed with water to obtain pitch microspheres. The obtained pitch microspheres are dried under reduced pressure at a temperature of 50℃ to remove chloroform and part of the light components, and the dried pitch microspheres are slowly heated to 200℃ in an air atmosphere for solidification and crosslinking, then heated to 800℃ in a nitrogen atmosphere for carbonization, to obtain pitch-based hard carbon micron sphere sodium storage material. The product obtained is a carbon sphere with a diameter of about 20 microns, and the carbon yield is 76%.

[0040] Example 8

[0041] The petroleum pitch, coal tar pitch, coal-based activated carbon and biomass-based activated carbon are fully ground to 400 mesh, the ratio of petroleum pitch to coal tar pitch is 2:1, the ratio of coal-based activated carbon to biomass-based activated carbon is 2:1, and the amount of carbonaceous filler added accounts for 20% of the weight fraction of pitch, then the solid mixture and chloroform are placed in a high-pressure reaction kettle for further heating, stirring and melting mixing, the amount of chloroform added accounts for 30% of the weight fraction of coal tar pitch, the melting mixing temperature is 60℃ higher than the softening point of pitch, the stirring rate is 300r / min, and the melting mixing time is 6h, to obtain a melting mixture. The above melting mixture is slowly injected from the bottom into another high-pressure reaction kettle by using a plunger pump, and a polyvinyl alcohol-containing aqueous solution is poured into the reaction kettle in advance, the amount of polyvinyl alcohol added accounts for 5% of the mass fraction of the aqueous solution, the amount of polyvinyl alcohol-containing aqueous solution added is 6 times the volume of the mixture in the kettle, then heating and stirring are carried out to disperse it into balls, the heating temperature is 200℃, the stirring rate is 700r / min, and the reaction time is 6h, after which the precipitate is washed with water to obtain pitch microspheres. The obtained pitch microspheres are dried under reduced pressure at a temperature of 100℃ to remove chloroform and part of the light components, and the dried pitch microspheres are slowly heated to 300℃ in an air atmosphere for solidification and crosslinking, then heated to 900℃ in a nitrogen atmosphere for carbonization, to obtain pitch-based hard carbon micron sphere sodium storage material. The product obtained is a carbon sphere with a diameter of about 13 microns, and the carbon yield is 75%.

[0042] Example 9

[0043] The petroleum pitch, coal tar pitch, coal-based activated carbon and biomass-based activated carbon are fully ground to 400 mesh, the ratio of petroleum pitch to coal tar pitch is 1:1, the ratio of coal-based activated carbon to biomass-based activated carbon is 1:1, and the amount of carbonaceous filler added accounts for 20% of the weight fraction of pitch, then the solid mixture and chloroform are placed in a high-pressure reaction kettle for further heating, stirring and melting mixing, the amount of chloroform added accounts for 30% of the weight fraction of coal tar pitch, the melting mixing temperature is 60℃ higher than the softening point of pitch, the stirring rate is 300r / min, and the melting mixing time is 6h, to obtain a melting mixture. The above melting mixture is slowly injected from the bottom into another high-pressure reaction kettle by using a plunger pump, and a polyvinyl alcohol-containing aqueous solution is poured into the reaction kettle in advance, the amount of polyvinyl alcohol added accounts for 5% of the mass fraction of the aqueous solution, the amount of polyvinyl alcohol-containing aqueous solution added is 6 times the volume of the mixture in the kettle, then heating and stirring are carried out to disperse it into balls, the heating temperature is 200℃, the stirring rate is 700r / min, and the reaction time is 6h, after which the precipitate is washed with water to obtain pitch microspheres. The obtained pitch microspheres are dried under reduced pressure at a temperature of 150℃ to remove chloroform and part of the light components, and the dried pitch microspheres are slowly heated to 400℃ in an air atmosphere for solidification and crosslinking, then heated to 1000℃ in a nitrogen atmosphere for carbonization, to obtain pitch-based hard carbon micron sphere sodium storage material. The product obtained is a carbon sphere with a diameter of about 6 microns, and the carbon yield is 68%.

[0044] Example 10

[0045] The petroleum pitch, coal tar pitch, coal-based activated carbon and biomass-based activated carbon are fully ground to 400 mesh, the ratio of petroleum pitch to coal tar pitch is 1:2, the ratio of coal-based activated carbon to biomass-based activated carbon is 1:2, and the amount of carbonaceous filler added accounts for 20% of the weight fraction of pitch, then the solid mixture and chloroform are placed in a high-pressure reaction kettle for further heating, stirring and melting mixing, the amount of chloroform added accounts for 30% of the weight fraction of coal tar pitch, the melting mixing temperature is 60℃ higher than the softening point of pitch, the stirring rate is 300r / min, and the melting mixing time is 6h, to obtain a melting mixture. The above melting mixture is slowly injected from the bottom into another high-pressure reaction kettle by using a plunger pump, and a polyvinyl alcohol-containing aqueous solution is poured into the reaction kettle in advance, the amount of polyvinyl alcohol added accounts for 5% of the mass fraction of the aqueous solution, the amount of polyvinyl alcohol-containing aqueous solution added is 6 times the volume of the mixture in the kettle, then heating and stirring are carried out to disperse it into balls, the heating temperature is 200℃, the stirring rate is 700r / min, and the reaction time is 6h, after which the precipitate is washed with water to obtain pitch microspheres. The obtained pitch microspheres are dried under reduced pressure at a temperature of 200℃ to remove chloroform and part of the light components, and the dried pitch microspheres are slowly heated to 500℃ in an air atmosphere for solidification and crosslinking, then heated to 1100℃ in a nitrogen atmosphere for carbonization, to obtain pitch-based hard carbon micron sphere sodium storage material. The product obtained is a carbon sphere with a diameter of about 5 microns, and the carbon yield is 69%.

[0046] Example 11

[0047] The petroleum pitch, coal tar pitch, coal-based activated carbon and biomass-based activated carbon are fully ground to 400 mesh, the ratio of petroleum pitch to coal tar pitch is 1:3, the ratio of coal-based activated carbon to biomass-based activated carbon is 1:3, and the amount of carbonaceous filler added accounts for 20% of the weight fraction of pitch, then the solid mixture and chloroform are placed in a high-pressure reaction kettle for further heating, stirring and melting mixing, the amount of chloroform added accounts for 30% of the weight fraction of coal tar pitch, the melting mixing temperature is 60℃ higher than the softening point of pitch, the stirring rate is 300r / min, and the melting mixing time is 6h, to obtain a melting mixture. The above melting mixture is slowly injected from the bottom into another high-pressure reaction kettle by using a plunger pump, and a polyvinyl alcohol-containing aqueous solution is poured into the reaction kettle in advance, the amount of polyvinyl alcohol added accounts for 5% of the mass fraction of the aqueous solution, the amount of polyvinyl alcohol-containing aqueous solution added is 6 times the volume of the mixture in the kettle, then heating and stirring are carried out to disperse it into balls, the heating temperature is 200℃, the stirring rate is 700r / min, and the reaction time is 6h, after which the precipitate is washed with water to obtain pitch microspheres. The obtained pitch microspheres are dried under reduced pressure at a temperature of 100℃ to remove chloroform and part of the light components, and the dried pitch microspheres are slowly heated to 400℃ in an air atmosphere for solidification and crosslinking, then heated to 1200℃ in a nitrogen atmosphere for carbonization, to obtain pitch-based hard carbon micron sphere sodium storage material. The product obtained is a carbon sphere with a diameter of about 0.5 microns, and the carbon yield is 64%.

[0048] Example 12

[0049] Petroleum pitch, coal-tar pitch, coal-based activated carbon and carbon black were fully ground to 400 mesh, the ratio of petroleum pitch to coal-tar pitch was 1:1, the ratio of coal-based activated carbon to carbon black was 1:1, and the amount of carbonaceous filler added accounted for 20% of the weight fraction of pitch, then the solid mixture and chloroform were placed in a high-pressure reaction kettle for continued heating, stirring, melting and mixing, the amount of chloroform added accounted for 30% of the weight fraction of coal-tar pitch, the melting and mixing temperature was 60°C higher than the softening point of pitch, the stirring rate was 300 r / min, the melting and mixing time was 6 h, and the melting and mixing material was obtained. The above melting and mixing material was slowly injected from the bottom into another high-pressure reaction kettle using a plunger pump, the reaction kettle was filled with an aqueous solution containing polyvinyl alcohol in advance, the amount of polyvinyl alcohol added accounted for 5% of the mass fraction of the aqueous solution, the amount of aqueous solution containing polyvinyl alcohol added was 6 times the volume of the mixture in the kettle, then heating and stirring were carried out to disperse it into balls, the heating temperature was 200°C, the stirring rate was 700 r / min, the reaction time was 6 h, and after the end, water was used to rinse the precipitate to obtain pitch microspheres. The obtained pitch microspheres were dried under reduced pressure at a temperature of 100°C to remove chloroform and part of the light components, and the dried pitch microspheres were slowly heated to 400°C in an air atmosphere for solidification and crosslinking, then heated to 1300°C in a nitrogen atmosphere for carbonization, and a pitch-based hard carbon micron sphere sodium storage material was obtained. The product obtained was a carbon sphere with a diameter of about 3 microns, and the carbon yield was 59%.

[0050] Example 13

[0051] Petroleum pitch, coal-tar pitch, coal-based activated carbon and carbon black were fully ground to 400 mesh, the ratio of petroleum pitch to coal-tar pitch was 1:1, the ratio of coal-based activated carbon to carbon black was 1:1, and the amount of carbonaceous filler added accounted for 20% of the weight fraction of pitch, then the solid mixture and chloroform were placed in a high-pressure reaction kettle for continued heating, stirring, melting and mixing, the amount of chloroform added accounted for 30% of the weight fraction of coal-tar pitch, the melting and mixing temperature was 60°C higher than the softening point of pitch, the stirring rate was 300 r / min, the melting and mixing time was 6 h, and the melting and mixing material was obtained. The above melting and mixing material was slowly injected from the bottom into another high-pressure reaction kettle using a plunger pump, the reaction kettle was filled with an aqueous solution containing polyvinyl alcohol in advance, the amount of polyvinyl alcohol added accounted for 5% of the mass fraction of the aqueous solution, the amount of aqueous solution containing polyvinyl alcohol added was 6 times the volume of the mixture in the kettle, then heating and stirring were carried out to disperse it into balls, the heating temperature was 200°C, the stirring rate was 700 r / min, the reaction time was 6 h, and after the end, water was used to rinse the precipitate to obtain pitch microspheres. The obtained pitch microspheres were dried under reduced pressure at a temperature of 100°C to remove chloroform and part of the light components, and the dried pitch microspheres were slowly heated to 400°C in an air atmosphere for solidification and crosslinking, then heated to 1400°C in a nitrogen atmosphere for carbonization, and a pitch-based hard carbon micron sphere sodium storage material was obtained. The product obtained was a carbon sphere with a diameter of about 4 microns, and the carbon yield was 62%.

[0052] Example 14

[0053] Petroleum pitch, coal tar pitch, coal-based activated carbon and microcrystalline graphite were ground to 400 mesh, the ratio of petroleum pitch to coal tar pitch was 1:1, the ratio of coal-based activated carbon to microcrystalline graphite was 1:1, and the amount of carbonaceous filler added was 20% by weight of the pitch. The solid mixture and chloroform were then placed in a high-pressure reaction kettle and heated and stirred to melt and mix. The amount of chloroform added was 30% by weight of the coal tar pitch, the melting and mixing temperature was 60°C higher than the softening point of the pitch, the stirring rate was 300 r / min, and the melting and mixing time was 6 h to obtain a melt mixture. The melt mixture was slowly injected from the bottom into another high-pressure reaction kettle using a plunger pump, and a polyvinyl alcohol-containing aqueous solution was pre-filled into the reaction kettle. The amount of polyvinyl alcohol added was 5% by mass of the aqueous solution, and the amount of polyvinyl alcohol-containing aqueous solution added was 6 times the volume of the mixture in the kettle. The mixture was then heated and stirred to disperse into spheres. The heating temperature was 200°C, the stirring rate was 700 r / min, and the reaction time was 6 h. After the reaction, the precipitate was washed with water to obtain pitch microspheres. The pitch microspheres were dried under reduced pressure at a temperature of 100°C to remove chloroform and some light components. The dried pitch microspheres were slowly heated to 400°C in an air atmosphere for solidification and crosslinking, and then heated to 1500°C in a nitrogen atmosphere for carbonization to obtain pitch-based hard carbon micron sphere sodium storage material. The product was a carbon sphere with a diameter of about 2 microns, and the carbon yield was 65%.

[0054] Example 15

[0055] Petroleum pitch, coal-tar pitch, coal-based activated carbon and needle coke were ground to 400 mesh, the ratio of petroleum pitch to coal-tar pitch was 1:1, the ratio of coal-based activated carbon to needle coke was 1:1, and the amount of carbonaceous filler added was 20% by weight of the pitch. The solid mixture and chloroform were then placed in a high-pressure reaction kettle and heated and stirred to melt and mix. The amount of chloroform added was 30% by weight of the coal-tar pitch, the melting and mixing temperature was 60°C higher than the softening point of the pitch, the stirring rate was 300 r / min, and the melting and mixing time was 6 h to obtain a melt mixture. The melt mixture was slowly injected from the bottom into another high-pressure reaction kettle using a plunger pump, and a polyvinyl alcohol-containing aqueous solution was pre-filled into the reaction kettle. The amount of polyvinyl alcohol added was 5% by mass of the aqueous solution, and the amount of polyvinyl alcohol-containing aqueous solution added was 6 times the volume of the mixture in the kettle. The mixture was then heated and stirred to disperse into spheres. The heating temperature was 200°C, the stirring rate was 700 r / min, and the reaction time was 6 h. After the reaction, the precipitate was washed with water to obtain pitch microspheres. The pitch microspheres were dried under reduced pressure at a temperature of 100°C to remove chloroform and some light components. The dried pitch microspheres were slowly heated to 400°C in an air atmosphere for curing and crosslinking, and then heated to 1200°C in a nitrogen atmosphere for carbonization to obtain pitch-based hard carbon micron sphere sodium storage material. The product obtained was a carbon sphere with a diameter of about 3 microns, and the carbon yield was 59%.

[0056] Comparative Example 1

[0057] This comparative example used commercial capacitive carbon PF50 as electrode material for sodium battery performance test.

[0058] Table 1

[0059]

[0060] The content not described in detail in the specification of the present application belongs to the prior art known to those skilled in the art. Although the above describes the specific embodiments of the present application for the purpose of facilitating those skilled in the art to understand the present application, it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions utilizing the concept of the present application are within the scope of protection.

Claims

1. A method for preparing pitch-based hard carbon microspheres sodium storage material, characterized by: The asphalt raw material and carbonaceous filler are ground, sieved and dried to obtain a solid mixture, then a viscosity reducer is added to the solid mixture, and the mixture is melted and mixed by heating and stirring to obtain a molten mixture, an aqueous solution containing a surfactant is pre-filled in a high-pressure reaction kettle, and then the molten mixture is slowly injected into the high-pressure reaction kettle from the bottom through a perforated sieve plate for heating and stirring to obtain asphalt microspheres, the asphalt microspheres are subjected to reduced pressure drying, heating in an air atmosphere for curing and crosslinking, and then heating in a nitrogen atmosphere for carbonization to obtain asphalt-based hard carbon micron sphere sodium storage material. The temperature of the reduced pressure drying is 50-200°C. The carbonaceous filler includes one or a mixture of two of coal-based activated carbon, biomass-based activated carbon, carbon black, acetylene black, microcrystalline graphite, and needle coke, and the addition amount is 1-30% by weight of the raw asphalt.

2. The method for preparing a pitch-based hard carbon microsphere sodium storage material according to claim 1, characterized in that: The asphalt raw material includes one or a mixture of two of petroleum asphalt and coal tar pitch.

3. The method for preparing a pitch-based hard carbon microsphere sodium storage material according to claim 1, characterized in that: The viscosity reducer is an organic solvent, including one of toluene, quinoline, pyridine, 1,2-dichloroethane, and chloroform, and the addition amount is 10-50% by weight of the raw asphalt.

4. The method for preparing a pitch-based hard carbon microsphere sodium storage material according to claim 1, characterized in that: The surfactant includes one of polyvinyl alcohol, polyethylene glycol, stearic acid, sodium dodecylbenzenesulfonate, Span, and Tween, and the addition amount is 1-10% by mass of the aqueous solution; and the addition amount of the aqueous solution containing the surfactant is 2-10 times the volume of the kettle mixture.

5. The method for preparing a pitch-based hard carbon microsphere sodium storage material according to claim 1, characterized in that: The asphalt raw material and carbonaceous filler are ground and sieved through a perforated sieve plate made of stainless steel with a mesh size of 200-500 mesh.

6. The method for preparing a pitch-based hard carbon microsphere sodium storage material according to claim 1, characterized in that: The temperature of the melting and mixing in the heating and stirring to obtain the molten mixture is 10-100°C higher than the softening point of the asphalt, the stirring speed is 100-500 r / min, and the melting and mixing time is 1-10 h.

7. The method for preparing a pitch-based hard carbon microsphere sodium storage material according to claim 1, characterized in that: The heating temperature in the heating and stirring in the high-pressure reaction kettle to obtain the asphalt microspheres is 100-300°C, the stirring speed is 300-1000 r / min, and the reaction time is 2-10 h.

8. The method according to claim 1, wherein the method is characterized by: The temperature of the heating in an air atmosphere for curing and crosslinking is 200-500°C, and the temperature of the heating in a nitrogen atmosphere for carbonization is 800-1500°C.

9. The asphalt-based hard carbon micron sphere sodium storage material prepared by the method of claim 1 is used in a sodium ion battery.

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