CN113860313B - Amorphous boron carbide and preparation method and application thereof - Google Patents
Amorphous boron carbide and preparation method and application thereof Download PDFInfo
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- 229910052580 B4C Inorganic materials 0.000 title claims abstract description 80
- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 title claims abstract description 80
- 238000002360 preparation method Methods 0.000 title claims abstract description 26
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 59
- 238000005087 graphitization Methods 0.000 claims abstract description 53
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 43
- 239000011812 mixed powder Substances 0.000 claims abstract description 39
- 238000010438 heat treatment Methods 0.000 claims abstract description 33
- 238000002156 mixing Methods 0.000 claims abstract description 31
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims abstract description 28
- 229910052796 boron Inorganic materials 0.000 claims abstract description 28
- 230000001681 protective effect Effects 0.000 claims abstract description 26
- 229910021383 artificial graphite Inorganic materials 0.000 claims abstract description 24
- 238000001816 cooling Methods 0.000 claims abstract description 16
- 239000003575 carbonaceous material Substances 0.000 claims description 31
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical group [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 28
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 19
- 239000007770 graphite material Substances 0.000 claims description 17
- 238000000498 ball milling Methods 0.000 claims description 15
- 229910052786 argon Inorganic materials 0.000 claims description 14
- 239000002245 particle Substances 0.000 claims description 14
- 239000003638 chemical reducing agent Substances 0.000 claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 claims description 8
- 239000003830 anthracite Substances 0.000 claims description 8
- 229910052810 boron oxide Inorganic materials 0.000 claims description 8
- 239000002006 petroleum coke Substances 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 8
- 239000000571 coke Substances 0.000 claims description 7
- 239000010426 asphalt Substances 0.000 claims description 6
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 6
- 239000004327 boric acid Substances 0.000 claims description 6
- 239000011329 calcined coke Substances 0.000 claims description 6
- -1 semicoke Substances 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 239000000758 substrate Substances 0.000 claims description 5
- 239000003350 kerosene Substances 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 3
- 239000003054 catalyst Substances 0.000 abstract description 27
- 229910002804 graphite Inorganic materials 0.000 abstract description 16
- 239000010439 graphite Substances 0.000 abstract description 16
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 7
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 7
- 238000006243 chemical reaction Methods 0.000 abstract description 6
- 230000003197 catalytic effect Effects 0.000 description 9
- 239000000843 powder Substances 0.000 description 9
- 238000005303 weighing Methods 0.000 description 6
- 239000007772 electrode material Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 229910052573 porcelain Inorganic materials 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 3
- 239000010431 corundum Substances 0.000 description 3
- 229910052593 corundum Inorganic materials 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000010742 number 1 fuel oil Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011331 needle coke Substances 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/90—Carbides
- C01B32/914—Carbides of single elements
- C01B32/991—Boron carbide
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/205—Preparation
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
Abstract
The invention discloses amorphous boron carbide and a preparation method and application thereof, wherein the preparation method comprises the following steps: uniformly mixing a pre-selected carbon source and a boron source to obtain uniformly mixed powder; and heating the uniformly mixed powder to 800-1500 ℃ under a protective atmosphere, preserving heat for 1-5h, and cooling to room temperature to prepare the amorphous boron carbide. In summary, the invention provides a preparation method of an amorphous catalyst for solving the problems of high production cost, low graphitization degree, influence on the capacity of a lithium ion battery cathode and low initial coulombic efficiency caused by overhigh reaction temperature in the existing artificial graphite production process; the amorphous catalyst can improve graphitization degree and reduce graphitization temperature, thereby improving capacity and first coulombic efficiency of the graphite cathode.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, relates to the technical field of graphitization of carbon-based materials, and in particular relates to amorphous boron carbide and a preparation method and application thereof.
Background
The lithium ion battery is a representative of a new generation of energy storage devices due to the advantages of higher energy density, ultra-small self-discharge effect, green pollution-free performance and the like. To date, artificial graphite is still the mainstream negative electrode material of lithium ion batteries, and is in an irreplaceable position in commercial lithium ion batteries due to the characteristics of low potential, low volume expansion, stable cycle life, higher capacity and the like.
However, the synthetic temperature of the artificial graphite prepared by needle coke and the like is up to 3000 ℃, which not only has high requirements on equipment, but also can bring great power and equipment loss, and is certainly unfavorable for controlling the cost; in other production technologies using low-cost carbon-based materials (such as coal, petroleum coke, and coal oil coke) as raw materials, even if the performance of the graphite material obtained at the temperature is greatly improved, the graphite conversion rate is low, the temperature required by the reaction is too high, the specific capacity and the theoretical capacity still have great difference, and the expected target is not achieved.
In view of the problems of high temperature graphitization, researchers find that catalytic graphitization is expected to solve the problem that substances such as metals with special properties, compounds thereof, nonmetallic compounds and the like are added into the ingredients, so that the graphitization of the carbon-based material at a lower temperature or the graphitization degree at the same temperature is promoted. The currently selected catalysts mainly comprise nickel, cobalt, iron, manganese, calcium, silicon and other elements and compounds thereof, but the effect obtained by the catalysts is not obvious in the aspects of improving the graphitization degree and controlling the graphitization temperature. In addition, boron has a good effect on catalyzing graphitization of the carbon material, but has high cost and is not suitable for commercial mass production of artificial graphite.
In view of the above, it is desirable to provide a catalyst which is low in cost and can effectively catalyze graphitization, increase graphitization degree of a carbon-based material or reduce graphitization temperature.
Disclosure of Invention
The invention aims to provide amorphous boron carbide and a preparation method and application thereof, so as to solve one or more technical problems. Specifically, the invention provides a preparation method of an amorphous catalyst for solving the problems that the existing artificial graphite production process has high production cost and low graphitization degree caused by high reaction temperature, thereby influencing the capacity of a lithium ion battery cathode and the first coulombic efficiency; the amorphous catalyst can improve graphitization degree and reduce graphitization temperature, thereby improving capacity and first coulombic efficiency of the graphite cathode.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention discloses a preparation method of amorphous boron carbide, which comprises the following steps:
uniformly mixing a pre-selected carbon source and a boron source to obtain uniformly mixed powder;
and heating the uniformly mixed powder to 800-1500 ℃ under a protective atmosphere, preserving heat for 1-5h, and cooling to room temperature to prepare the amorphous boron carbide.
The invention is further improved in that the boron source is selected from one or two of diboron trioxide and boric acid; the carbon source is selected from one or more of anthracite, semicoke, petroleum coke, kerosene coke, calcined coke and asphalt.
The invention is further improved in that in the process of uniformly mixing the pre-selected carbon source and the boron source, the mass ratio of the carbon reducing agent to the boron oxide is 0.6.
The invention further improves that the step of evenly mixing the pre-selected carbon source and the boron source to obtain evenly mixed powder specifically comprises the following steps: and ball milling the pre-selected carbon source and the boron source, and then uniformly mixing to obtain uniformly mixed powder.
The invention is further improved in that in the process of heating the uniformly mixed powder to 800-1500 ℃ under the protective atmosphere, the heating rate is 10 ℃/min, and the protective atmosphere is argon or nitrogen.
The amorphous boron carbide prepared by any one of the preparation methods of the invention.
The application of the amorphous boron carbide prepared by the preparation method is used for catalyzing the graphitization of the carbon-based material.
The invention further improves that the step of catalyzing the graphitization of the carbon-based material specifically comprises the following steps:
carrying out ball milling treatment on amorphous boron carbide and a carbon substrate, and uniformly mixing to obtain mixed powder;
and heating the mixed powder to 2500-2800 ℃ under a protective atmosphere, preserving heat for 1-10 h, and cooling to room temperature to obtain the artificial graphite material.
The invention is further improved in that the particle size of the amorphous boron carbide in the mixed powder is 1-3 mu m; the particle size of the carbon-based material is between 5 and 15 mu m.
Compared with the prior art, the invention has the following beneficial effects:
amorphous boron carbide (B) prepared by the invention 4 C x ) Is synthesized at low temperature, and has low crystallization degree; further, when the catalyst is used as a catalyst, the graphitization degree of the carbon-based material can be remarkably improved by adding different contents of the substance, so that the specific capacity of the electrode material is improved; but it also reduces the graphitization temperature to some extent.
The boron source for preparing the amorphous boron carbide in the invention is B 2 O 3 Or H 3 BO 3 The carbon source is anthracite, semicoke, petroleum coke, coal oil coke, calcined coke, asphalt and the like, the cost of raw materials is very low, the preparation equipment is simple, the operation is convenient, and the mass industrial production is easy.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description of the embodiments or the drawings used in the description of the prior art will make a brief description; it will be apparent to those of ordinary skill in the art that the drawings in the following description are of some embodiments of the invention and that other drawings may be derived from them without undue effort.
FIG. 1 is a graph showing the comparison of the cycle performance of an electrode material charged and discharged at 0.5C after graphitizing and insulating for 1 hour at 2800 ℃ after amorphous boron carbide at 0%,10%,15% and 20% and 800 ℃ is added into semicoke in the embodiment of the invention;
FIG. 2 is a schematic diagram of a first charge-discharge curve of an electrode material charged and discharged at 0.1C after graphitizing and insulating for 1 hour at 2800 ℃ after amorphous boron carbide at 0%,10%,15% and 20% and 800 ℃ is added into semicoke in the embodiment of the invention;
FIG. 3 is a schematic diagram showing the rate performance curves of electrode materials charged and discharged at different currents after graphitizing and insulating for 1 hour at 2800 ℃ after amorphous boron carbide at 0%,10%,15% and 20% of 800 ℃ is added into semicoke in the embodiment of the invention;
FIG. 4 is a graph showing the comparison of cycle performance of graphite electrodes prepared by graphitizing and insulating semicoke added with 0% and 15% of 800 ℃ amorphous boron carbide at 2800 ℃ and 2500 ℃ for 1 hour in charge and discharge at 0.5C magnification in the embodiment of the invention;
FIG. 5 is a schematic diagram showing the first charge and discharge curves of a graphite electrode prepared by graphitizing and insulating semicoke added with 0% and 15% of 800 ℃ amorphous boron carbide at 2800 ℃ and 2500 ℃ for 1 hour in the embodiment of the invention at 0.1C;
FIG. 6 is a graph showing the comparison of the rate performance of graphite electrodes prepared by graphitizing and insulating semicoke added with 0% and 15% of 800 ℃ amorphous boron carbide at 2800 ℃ and 2500 ℃ for 1 hour respectively when the graphite electrodes are charged and discharged with different currents in the embodiment of the invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention is described in further detail below with reference to the attached drawing figures:
the preparation method of the amorphous boron carbide comprises the following steps:
uniformly mixing a carbon source and a boron source in a preset proportion to obtain uniformly mixed powder;
heating the uniformly mixed powder to 800-1500 ℃ at 10 ℃/min under a protective atmosphere, preserving heat for 1-5h, and cooling to room temperature to prepare the amorphous boron carbide.
Illustratively, the predetermined ratio is 0.6 (mass ratio of carbon reductant to boron oxide).
Specifically, uniformly mixing a carbon source and a boron source in a preset proportion specifically comprises: ball milling is carried out on the carbon source and the boron source in a preset proportion, and the mixture is uniformly mixed.
Specifically, the boron source is selected from low-cost diboron trioxide (B 2 O 3 ) Or boric acid (H) 3 BO 3 ) The carbon source used as the reducing agent can be selected from anthracite, semicoke, petroleum coke, kerosene coke, calcined coke or asphalt.
Specifically, the protective atmosphere is argon or nitrogen.
In summary, the embodiment of the invention aims to solve the problems that the existing artificial graphite production process is too high in production cost and low in graphitization degree caused by too high reaction temperature, so that the capacity of a lithium ion battery cathode and the first coulombic efficiency are affected, and particularly provides a method for improving the graphitization degree and the graphitization temperature by using an amorphous catalyst, so that the capacity of the graphite cathode and the first coulombic efficiency are improved.
An embodiment of the invention relates to amorphous boron carbide (B) 4 C x ) The preparation process of (2) is completed according to the following steps:
the boron source is selected from low-cost diboron trioxide (B) 2 O 3 ) Or boric acid (H) 3 BO 3 ) The carbon source used as the reducing agent may be selected from anthracite, semicoke, petroleum coke, kerosene coke, calcined coke, asphalt, etc.
And respectively weighing a carbon source and a boron source according to the mass ratio of the carbon reducing agent to the boron oxide of 0.6, wherein the boron source is easy to evaporate in the reaction process, so that the boron source is excessive in proportion to the theoretical ratio, and then pouring the weighed sample into a ball mill tank for uniform mixing.
And (3) transferring the uniformly mixed powder into a corundum porcelain boat, then placing the corundum porcelain boat into a tube furnace for heating, wherein the protective atmosphere is argon, and preserving heat for 1-5h after heating to a preset temperature.
And finally, slowly cooling the sample to room temperature along with a furnace to obtain black blocky amorphous boron carbide.
An embodiment of the invention relates to amorphous boron carbide (B) 4 C x ) The catalytic carbon-based material graphitization process includes:
firstly, putting amorphous boron carbide into a planetary ball mill for ball milling for 2-4 hours, controlling the particle size of the amorphous boron carbide to be 1-3 mu m, and fully contacting the amorphous boron carbide when the amorphous boron carbide is mixed with a carbon-based material so as to achieve the best catalytic effect. Then respectively weighing 10%,15% and 20% of amorphous boron carbide and carbon-based materials, uniformly mixing in a planetary ball mill, and controlling the particle size of the carbon-based materials to be 5-15 mu m.
And then filling the uniformly mixed powder into a graphite crucible. And then placing the artificial graphite material into a high-temperature graphitization furnace for heat treatment, wherein the temperature is set to 2500-2800 ℃, the heat preservation is carried out for 1-10 h, the protective atmosphere is argon, and after the heat preservation is finished, the artificial graphite material can be obtained by naturally cooling the artificial graphite material to room temperature.
Amorphous boron carbide (B) prepared by the invention 4 C x ) Is synthesized at low temperature, and has low crystallization degree; when the catalyst is used as a catalyst, the graphitization degree of the carbon-based material can be remarkably improved by adding different contents of the substance, so that the specific capacity of the electrode material is improved; but it also reduces the graphitization temperature to some extent.
The boron source for preparing the amorphous boron carbide in the invention is B 2 O 3 Or H 3 BO 3 The carbon source is anthracite, semicoke, petroleum coke, coal oil coke, calcined coke, asphalt and the like, the cost of raw materials is very low, the preparation equipment is simple, the operation is convenient, and the mass industrial production is easy.
The invention provides an amorphous boron carbide (B) 4 C x ) Preparation method of (C) and application of (C) in aspect of catalyzing graphitization of carbon-based materialThe method specifically comprises the following steps: reducing boron oxide at low temperature by using a carbothermic reduction method to obtain black blocky amorphous boron carbide; and adding the obtained amorphous boron carbide into a carbon-based material, and carrying out catalytic graphitization at high temperature to obtain the artificial graphite material with improved performance. The amorphous boron carbide provided by the invention not only can obviously improve the specific capacity of the carbon-based material, but also can reduce the graphitization temperature to a certain extent and improve the first coulomb efficiency of the carbon-based material, and the method is low in cost, simple and convenient to operate and suitable for large-scale production.
Example 1
The carbothermic process of preparing amorphous boron carbide includes the following steps:
mixing: according to the carbon reducing agent and B 2 O 3 The proportioning (weight ratio) of the powder is 0.6, the weighed powder is poured into a mixing tank, the ball-material ratio is 10:1, the rotating speed is 450r/min, and the powder is mixed in a planetary ball mill for 3 hours until the powder is completely uniform.
Carbothermic reduction: the evenly mixed powder is moved to a corundum porcelain boat with the length of 3 multiplied by 8cm, and then the porcelain boat is put into a tube furnace for heating. Argon is introduced for 20-30 min before heating to remove air in the quartz tube, then argon flow is controlled to be minimum to form an argon protective atmosphere, a heating program is set to heat up to 800-1500 ℃ at 10 ℃/min, then heat is preserved for 1-5h, finally, the sample is slowly cooled to room temperature along with a furnace, and finally, a black blocky product is obtained.
Example 2
The amorphous boron carbide catalytic graphitization method provided by the embodiment of the invention comprises the following steps of:
catalyst grinding and mixing: crushing massive amorphous boron carbide, and then putting the crushed amorphous boron carbide into a planetary ball mill for ball milling for 3 hours; then weighing a certain amount of carbon source powder, uniformly mixing in a planetary ball mill for 30min. The ball-material ratio is 10:1, the rotating speeds are all 450r/min. Mixing the ground catalyst and carbon source powder according to a certain proportion, and stirring for 1 hour by a mixer to obtain composite powder.
Catalytic graphitization: weighing 2g of the uniformly mixed amorphous boron carbide and carbon source powder, and transferring the amorphous boron carbide and carbon source powder into a graphite crucible; and then placing the artificial graphite material into a high-temperature graphitization furnace for heat treatment, wherein the protective atmosphere is argon, the temperature is raised to 2500-2800 ℃ for graphitization, then preserving the heat for 1-10 h, and naturally cooling to room temperature after the graphitization process is finished, thus obtaining the artificial graphite material.
The invention prepares the amorphous boron carbide by a simple carbothermic reduction method and uses the amorphous boron carbide as a catalyst to catalyze graphitization, thereby realizing a preparation method of the artificial graphite which can improve the capacity of a carbon-based material and reduce the graphitization temperature. The preparation process does not comprise any high-cost raw materials, is simple and convenient to operate, greatly reduces the production cost, and lays a foundation for industrialized mass production.
Example 3
The embodiment of the invention discloses a preparation method of amorphous boron carbide for catalytic graphitization, which specifically comprises the following steps:
1. respectively weigh 3 groups of 5g B 2 O 3 +3g semicoke sample, marked as #1, #2, #3 sample, mixing them thoroughly and uniformly according to the above steps, then transferring the #1 reactant into a tube furnace for heating, introducing argon for 20-30 min before heating to remove air in the quartz tube, and then controlling the argon flow to be minimum to form argon protective atmosphere;
2. heating to 800 ℃ at a heating rate of 10 ℃/min by setting a heating program, preserving heat for 1h, and slowly cooling the sample to room temperature along with a furnace to obtain black blocky amorphous boron carbide at 800 ℃.
Example 4
The embodiment of the present invention differs from embodiment 3 only in that: the heat-retaining temperature of sample #2 was set at 1200℃and the other experimental conditions were the same as in example 3, whereby a black block of amorphous boron carbide at 1200℃was obtained.
Example 5
Embodiments of the present invention differ from embodiments 3 and 4 only in that: the heat-retaining temperature of sample #3 was set at 1500℃and the other experimental conditions were the same as those of examples 3 or 4, whereby a black block of amorphous boron carbide at 1500℃was obtained.
Example 6
The method for preparing artificial graphite by catalytic graphitization of amorphous boron carbide at 800 ℃ prepared in the embodiment 3 comprises the following steps:
firstly crushing massive amorphous boron carbide, and then putting the crushed amorphous boron carbide into a ball milling tank for ball milling, wherein the ball-to-material ratio is 10:1, ball milling for 3 hours at the rotating speed of 450r/min, and controlling the particle size of the ball milling to be 1-3 mu m so that the particle size of the ball milling is smaller than that of the carbon-based material;
weighing 4 groups of semicoke, wherein the weight of each group is 5g, respectively weighing 800 ℃ amorphous boron carbide according to 0%,10%,15% and 20% of the weight of the semicoke, and putting the amorphous boron carbide and each group of semicoke into a mixer together for mixing for 1h to obtain uniformly mixed composite raw materials;
after the material mixing is finished, 2g of each group of mixture is respectively taken and moved into a graphite crucible, and corresponding marks are made; putting the prepared reactant into a vertical high-temperature graphitization furnace, and preparing for heat treatment;
the atmosphere of heat treatment is argon, after the vacuumizing in the furnace is finished, the air flow is kept to be minimum, a heating program is set, automatic heating is started after the temperature is 1200 ℃, the heating rate is 10 ℃/min, the temperature is kept for 1h after the temperature is increased to 2800 ℃, and then the sample is cooled to the room temperature along with the furnace, so that the artificial graphite material can be obtained.
The electrode prepared from the artificial graphite material prepared in the embodiment is assembled with a lithium sheet to form a semi-battery for testing the charge and discharge performance, and as can be seen from the cycle performance of fig. 1, the semicoke without 800 ℃ amorphous boron carbide shows extremely low battery capacity after graphitizing and insulating for one hour at 2800 ℃, and the highest specific charge capacity is only 238.7mAh g when the electrode is charged and discharged at 0.5C multiplying power -1 With the increase of the catalyst content, the capacity of the semicoke after graphitization is obviously improved. After 10%,15% and 20% of the catalyst are added respectively, the average specific capacity can reach 279.3mAh g respectively when the catalyst is charged and discharged at a multiplying power of 0.5C -1 、306.0mAh g -1 And 347.9mAh g -1 The method comprises the steps of carrying out a first treatment on the surface of the Compared with graphite without the catalyst, the specific capacity of the catalyst can be improved by 109.2mAh g at the highest -1 The expectation of the present invention was achieved.
From the first charge-discharge curve of fig. 2, the capacity is obviously improved, the first coulomb efficiency is improved to a certain extent, the first coulomb efficiency of the graphite electrode without the catalyst is 74.5%, and the first coulomb efficiency of the graphite electrode with the catalyst added with 10%,15% and 20% is 80.5%, 78.7% and 81.5%, respectively, so that the first coulomb efficiency of the graphite cathode can be improved to a certain extent by the catalyst, and the expectation of the invention is reached.
From the view of the multiplying power performance of the battery in fig. 3, the improvement of the semicoke capacity of the catalyst is consistent with the result of the cycle performance test, and the amorphous boron carbide can obviously improve the semicoke capacity.
Specific example 7:
the embodiment of the present invention is different from embodiment 6 in that: the temperature of the catalytic graphitization is set to 2500 ℃, and other conditions are the same as those of the example 6, so that the amorphous boron carbide catalyzed artificial graphite material with the temperature of 800 ℃ at 2500 ℃ is finally obtained.
The artificial graphite material prepared in the example of the present invention and the artificial graphite material prepared without the catalyst in example 4 were fabricated into electrodes, and assembled into half cells for performance test.
As can be seen from the comparison of the cycle performance in FIG. 4, after the original semicoke is graphitized and kept at 2800 ℃ for one hour, the average capacity of the original semicoke is 232.3mA h g-1 when the original semicoke is charged and discharged for 100 circles or so, and after 15% of 800 ℃ amorphous boron carbide is added into the original semicoke, the original semicoke is graphitized and kept at 2500 ℃ for one hour, and then charged and discharged under the same conditions, the average capacity of the original semicoke is 296.9mA h g -1 I.e. the specific capacity can be increased by 64.6mA h g after the graphitization temperature is reduced by 300 DEG C -1 . This means that the carbocoal reaches a higher degree of graphitization at a lower temperature, i.e., the graphitization temperature is reduced, which meets the expectations of the present invention.
As can be seen from the first charge-discharge curve of the battery in fig. 5, after the temperature is reduced by 300 ℃, the electrode capacity of the amorphous boron carbide added with 15% of 800 ℃ is obviously improved, and the first discharge efficiency is 79.4%, compared with the graphite without the catalyst, the first coulombic efficiency is slightly improved, which also shows that the semicoke reaches higher graphitization degree at lower temperature, and the expectation of the invention is reached.
Fig. 6 is a graph comparing charge and discharge performance of the above two batteries at different rates, and it also demonstrates that the catalyst reduces graphitization temperature after adding 15% of amorphous boron carbide at 800 ℃, but the improvement of the rate performance of the batteries is not obvious from the graph.
Example 8
The invention discloses a preparation method of amorphous boron carbide, which comprises the following steps:
uniformly mixing a pre-selected carbon source and a boron source to obtain uniformly mixed powder;
and heating the uniformly mixed powder to 800 ℃ at a heating rate of 10 ℃/min under a protective atmosphere, preserving heat for 5 hours, and cooling to room temperature to prepare the amorphous boron carbide.
The boron source is selected from diboron trioxide; the carbon source is selected from anthracite. When mixing, the mass ratio of the carbon reducing agent to the boron oxide is 0.6, and the protective atmosphere is argon.
Example 9
The invention discloses a preparation method of amorphous boron carbide, which comprises the following steps:
uniformly mixing a pre-selected carbon source and a boron source to obtain uniformly mixed powder;
and heating the uniformly mixed powder to 1200 ℃ at a heating rate of 10 ℃/min under a protective atmosphere, preserving heat for 1h, and cooling to room temperature to prepare the amorphous boron carbide.
The boron source is selected from diboron trioxide and boric acid; the carbon source is selected from anthracite, semicoke and petroleum coke. When mixing, the mass ratio of the carbon reducing agent to the boron oxide is 0.6, and the protective atmosphere is nitrogen.
Example 10
The invention discloses a preparation method of amorphous boron carbide, which comprises the following steps:
uniformly mixing a pre-selected carbon source and a boron source to obtain uniformly mixed powder;
and heating the uniformly mixed powder to 1500 ℃ under a protective atmosphere, preserving heat for 3 hours, and cooling to room temperature to prepare the amorphous boron carbide.
The boron source selects boric acid; and the carbon source is semicoke. When mixing, the mass ratio of the carbon reducing agent to the boron oxide is 0.6, and the protective atmosphere is nitrogen.
Example 11
The application of the amorphous boron carbide prepared by the preparation method is used for catalyzing the graphitization of the carbon-based material; the step of catalyzing graphitizing the carbon-based material specifically comprises the following steps:
carrying out ball milling treatment on amorphous boron carbide and a carbon substrate, and uniformly mixing to obtain mixed powder;
and heating the mixed powder to 2500 ℃ in a protective atmosphere, preserving heat for 10 hours, and cooling to room temperature to obtain the artificial graphite material. In the mixed powder, the particle size of the amorphous boron carbide is 1 mu m; the particle size of the carbon-based material was 5. Mu.m.
Example 12
The application of the amorphous boron carbide prepared by the preparation method is used for catalyzing the graphitization of the carbon-based material; the step of catalyzing graphitizing the carbon-based material specifically comprises the following steps:
carrying out ball milling treatment on amorphous boron carbide and a carbon substrate, and uniformly mixing to obtain mixed powder;
and heating the mixed powder to 2600 ℃ in a protective atmosphere, preserving heat for 5 hours, and cooling to room temperature to obtain the artificial graphite material. In the mixed powder, the particle size of the amorphous boron carbide is between 2 mu m; the particle size of the carbon-based material is between 10 μm.
Example 13
The application of the amorphous boron carbide prepared by the preparation method is used for catalyzing the graphitization of the carbon-based material; the step of catalyzing graphitizing the carbon-based material specifically comprises the following steps:
carrying out ball milling treatment on amorphous boron carbide and a carbon substrate, and uniformly mixing to obtain mixed powder;
and heating the mixed powder to 2800 ℃ in a protective atmosphere, preserving heat for 1h, and cooling to room temperature to obtain the artificial graphite material. In the mixed powder, the particle size of the amorphous boron carbide is between 3 mu m; the particle size of the carbon-based material is between 15 μm.
Finally, it should be noted that: the above embodiments are only for illustrating the technical aspects of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.
Claims (3)
1. The preparation method of the amorphous boron carbide is characterized by comprising the following steps of:
uniformly mixing a pre-selected carbon source and a boron source to obtain uniformly mixed powder;
heating the uniformly mixed powder to 800-1500 ℃ under a protective atmosphere, preserving heat for 1-5 hours, and cooling to room temperature to prepare amorphous boron carbide;
wherein the boron source is selected from one or two of diboron trioxide and boric acid; the carbon source is selected from one or more of anthracite, semicoke, petroleum coke, kerosene coke, calcined coke and asphalt;
in the process of uniformly mixing the pre-selected carbon source and the boron source, the mass ratio of the carbon reducing agent to the boron oxide is 0.6;
the step of uniformly mixing the pre-selected carbon source and the boron source to obtain uniformly mixed powder specifically comprises the following steps: ball milling is carried out on the pre-selected carbon source and the boron source, and then the mixture is uniformly mixed to obtain uniformly mixed powder;
heating the uniformly mixed powder to 800-1500 ℃ in a protective atmosphere, wherein the heating rate is 10 ℃/min;
and heating the uniformly mixed powder to 800-1500 ℃ in a protective atmosphere, wherein the protective atmosphere is argon or nitrogen.
2. An amorphous boron carbide prepared by the method of claim 1.
3. Use of amorphous boron carbide according to claim 2 for catalyzing graphitization of carbon-based materials;
the step for catalyzing graphitization of the carbon-based material specifically comprises the following steps:
carrying out ball milling treatment on amorphous boron carbide and a carbon substrate, and uniformly mixing to obtain mixed powder;
heating the mixed powder to 2500-2800 ℃ under protective atmosphere, preserving heat for 1-10 h, and cooling to room temperature to obtain an artificial graphite material;
in the mixed powder, the particle size of the amorphous boron carbide is between 1 and 3 mu m; the particle size of the carbon-based material is between 5 and 15 mu m.
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