CN108017054B - Method for preparing mixed expanded graphite from microcrystalline graphite and flake graphite - Google Patents
Method for preparing mixed expanded graphite from microcrystalline graphite and flake graphite Download PDFInfo
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- CN108017054B CN108017054B CN201711405656.1A CN201711405656A CN108017054B CN 108017054 B CN108017054 B CN 108017054B CN 201711405656 A CN201711405656 A CN 201711405656A CN 108017054 B CN108017054 B CN 108017054B
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Abstract
The invention discloses a method for preparing mixed expanded graphite from microcrystalline graphite and crystalline flake graphite, which comprises the steps of taking microcrystalline graphite and crystalline flake graphite as raw materials, carrying out ball milling, then placing a ball-milling mixture in a muffle furnace for calcination and activation under inert atmosphere, and then carrying out chemical intercalation treatment on the activated mixture to obtain expandable mixed graphite; and (3) placing the expandable mixed graphite into a muffle furnace to expand at 1000 ℃ to obtain the micro-expanded graphite material. The expanded graphite material prepared by the invention is of a structure that flocculent microcrystalline graphite is mixed between flake graphite sheets, the structure that flocculent microcrystalline graphite is mixed between the flake graphite sheets is more beneficial to conduction between electrons and adsorption of ions, and is beneficial to modification research of subsequent expanded graphite, and meanwhile, the structure has the advantages of both flake graphite and microcrystalline graphite, and overcomes the defects of poor orientation, low expansion multiple and the like of the expanded flake graphite.
Description
Technical Field
The invention belongs to the technical field of material preparation, and particularly relates to a method for preparing mixed expanded graphite from microcrystalline graphite and crystalline flake graphite.
Background
Expanded graphite is a carbon material. Expandable graphite is used as a raw material, when the material is treated at high temperature (generally 700-1200 ℃), substances inserted between the expanded graphite layers are rapidly decomposed, generated gas forms high pressure in the interlayer region of the expandable graphite and expands along the c-axis direction in a high-power manner, and the volume density is 0.7-1.8 g/cm3The concentration of the carbon-containing compound is 0.003 to 0.03g/cm3The expansion times are tens to hundreds of times. The expanded graphite has a loose structure, is porous and vermiform, has a large surface area and high surface energy, so that the expanded graphite has excellent liquid phase adsorption performance, good plasticity, good flexibility, ductility and sealing performance, and is widely applied to the fields of environmental protection, machinery, chemical engineering, aerospace, atomic energy and the like.
At present, the raw material used in the technology of preparing the expanded graphite material by using natural graphite as the raw material is generally crystalline large flake graphite. The crystalline graphite has large scale and good aggregate orientation. However, graphite materials having poor orientation and good homogeneity are required for electrode materials for batteries and supercapacitors, and therefore, crystalline graphite is often spheroidized, which is not preferable. The microcrystalline graphite has fine particles, poor orientation of the aggregate and good homogeneity, and the expanded microcrystalline graphite obtained after expansion treatment has more excellent electrical property.
Therefore, the advantages of the two kinds of graphite can be combined, the microcrystalline graphite and the microcrystalline graphite are mixed and expanded together to prepare the mixed expanded graphite, the obtained mixed expanded graphite has better electrochemical performance and can also be used as a better adsorption material, the specific surface area is greatly improved compared with the prior art, and no research report on a technical method for preparing an expanded graphite material by mixing the microcrystalline graphite and the crystalline flake graphite is found at present.
Disclosure of Invention
The invention aims to provide a method for preparing mixed expanded graphite from microcrystalline graphite and crystalline flake graphite, aiming at the problems in the prior art.
The purpose of the invention is realized by the following technical scheme:
a method for preparing mixed expanded graphite from microcrystalline graphite and crystalline flake graphite comprises the following steps:
s1, ball milling crystalline flake graphite and microcrystalline graphite in a mass ratio of 1:1 until the particle size is 200 meshes, and obtaining a mixture; the carbon content of the flake graphite is not lower than 85%, the microcrystalline graphite is Chenzhou Shandong pond graphite powder, and the carbon content of the microcrystalline graphite is 70-80%; the ball-material ratio in the ball milling process is 6:1, the ball milling time is 6h, and the rotating speed is 500 r/min;
s2, placing the mixture obtained in the step S1 in a muffle furnace, heating to 500 ℃ at the speed of 30 ℃/min under the inert atmosphere, preserving heat for 20min, and cooling to room temperature for later use;
s3, carrying out chemical intercalation treatment on the mixture subjected to the heat treatment of S2 to obtain expandable mixed graphite;
s4, placing the expandable mixed graphite obtained in the step S3 into a muffle furnace to be expanded for 30S at 1000 ℃ to obtain a mixed expanded graphite material;
wherein: the step S3 comprises the following steps:
s31, mixing perchloric acid and the mixed powder obtained in the step S2 according to a liquid-solid ratio of 20: 1L/Kg of the mixture is mixed and stirred evenly;
s32, mixing the mixed powder with potassium permanganate according to a mass ratio of 1: 8, adding potassium permanganate, uniformly stirring at room temperature, heating to 70 ℃, and continuously stirring for reaction for 2 hours;
s33, adding deionized water to raise the temperature in the reaction device to 100 ℃, and continuing stirring for reaction for 2 hours;
s34, filtering, washing and drying the filtered substance to obtain the expandable mixed graphite.
The invention creatively mixes and expands the microcrystalline graphite and the crystalline flake graphite to prepare the mixed expanded graphite material, in the ball milling process, the crystalline flake graphite and the microcrystalline graphite with proper mass ratio are fully mixed, in the ball milling process, part of microcrystalline graphite particles can enter the crystalline flake graphite layers to be fully mixed, and heat treatment is carried out after mixing, so that the ball milling mixed material can be activated by the heat treatment, sublimable impurities in the raw materials can be treated, and chemical intercalation treatment is carried out immediately after the heat treatment, so that the intercalation effect and efficiency can be improved, and the subsequent expansion treatment process is more facilitated.
In the swelling treatment process of the ball-milling mixture, the structures of the flake graphite and the microcrystalline graphite are different, the change of the swelling process is different, the flake graphite swelling process expands the inter-sheet distance, the microcrystalline graphite swells to form flocculent, the structure of the mixture after swelling shows that the flocculent expanded microcrystalline graphite between the flake graphite is connected between the flake graphite sheets, the structure of the flocculent microcrystalline graphite between the flake graphite sheets is more beneficial to conduction between electrons and adsorption of ions, and is beneficial to the modification research of subsequent expanded graphite, and the structure has the advantages of the flake graphite and the microcrystalline graphite, and overcomes the defects of poor orientation of the expanded flake graphite, low expansion multiple of the expanded microcrystalline graphite and the like.
Preferably, the inert atmosphere of step S2 is one of nitrogen and argon,
the invention also discloses the mixed expanded graphite material prepared by the preparation method of the mixed expanded graphite for the lithium ion battery.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention adopts the microcrystalline graphite and the crystalline flake graphite to prepare the mixed expanded graphite material, the reserves of the microcrystalline graphite in China are large, the price is low, and the low-added-value utilization is mostly realized, and the invention provides a high-added-value utilization way for the microcrystalline graphite.
(2) The invention adopts microcrystalline graphite and crystalline flake graphite as raw materials, carries out puffing treatment on the mixed material to obtain the mixed expanded graphite material, expands the graphite interval while having high volume specific capacity, forms a micro-nano hole structure and prepares the high-multiple mixed expanded graphite material.
(3) In the process of expansion treatment of the ball-milling mixture, the structures of flake graphite and microcrystalline graphite are different, the change of the expansion process is different, the flake graphite expands to form interlayer spacing, the microcrystalline graphite expands to form flocculent, the structure of the mixture after expansion shows that the flocculent expanded microcrystalline graphite between the flake graphite is connected between the flake graphite layers, the structure of the flocculent microcrystalline graphite between the flake graphite layers is more beneficial to conduction between electrons and adsorption of ions, and is beneficial to the modification research of subsequent expanded graphite, and the structure has the advantages of the flake graphite and the microcrystalline graphite, and overcomes the defects of poor orientation, low expansion multiple, poor expansion effect and the like of the expanded flake graphite.
(4) The expanded microcrystalline graphite and flake graphite can effectively buffer the size change of the electrode material during charging and discharging, particularly during heavy current charging and discharging, reduce the damage to the electrode material and avoid the increase of irreversible capacity, so that the prepared micro-expanded graphite has better cycle stability and rate capability and can be used as a cathode of a lithium ion battery.
(5) The method has the advantages of cheap raw materials, short production period, obvious social and economic benefits and easy realization of industrial production.
Detailed Description
The invention is further illustrated by the following specific examples. The following examples are illustrative only and are not to be construed as unduly limiting the invention which may be embodied in many different forms as defined and covered by the summary of the invention. Reagents, compounds and apparatus employed in the present invention are conventional in the art unless otherwise indicated.
Example 1
The invention discloses a mixed expanded graphite material prepared by mixing microcrystalline graphite and crystalline flake graphite, which comprises the following steps: comprises a graphite expansion furnace, adopts a high-temperature expansion method, and comprises the following steps:
s1, taking a microcrystalline graphite raw material with 70% of carbon content and a crystalline graphite raw material with 85% of carbon content, wherein the mass ratio of crystalline graphite to microcrystalline graphite is 1:1, crushing and grinding, the ball-to-material ratio in the ball-milling process is 6:1, the ball-milling time is 6h, the rotating speed is 500r/min, and ball-milling is carried out until mixed graphite powder with the granularity of 200 meshes is obtained.
S2, placing the mixture obtained in the step S1 in a muffle furnace, heating to 500 ℃ at the speed of 30 ℃/min under the nitrogen atmosphere, preserving heat for 30min, and cooling to room temperature for later use.
S3, carrying out chemical intercalation treatment on the mixture after the heat treatment of S2 to obtain expandable mixed graphite, wherein the chemical intercalation treatment comprises the following specific steps:
s31, mixing perchloric acid and microcrystalline graphite powder according to a liquid-solid ratio of 20: 1L/Kg of the mixture is mixed and stirred evenly; s32, mixing the mixed powder with potassium permanganate according to the mass ratio of 1: 8, adding potassium permanganate, uniformly stirring at room temperature, heating to 70 ℃, and continuously stirring for reaction for 2 hours; s33, adding deionized water to raise the temperature in the reaction device to 100 ℃, and continuing stirring for reaction for 2 hours; s34, filtering, and then washing and drying the filtered substance to obtain the expandable mixed graphite.
And S4, placing the expandable mixed graphite obtained in the step S3 into a muffle furnace to be expanded for 30S at 1000 ℃ to obtain the mixed expanded graphite material.
The aperture distribution range of the mixed expanded graphite material obtained in the embodiment is 1-100 nm, and the specific surface area is 486 m2Per g, a multiple of 149-fold expansion.
Comparative example 1
Comparative example 1 differs from example 1 in that: comparative example 1 was not provided with step S2, and the other steps were the same as in example 1.
The pore diameter distribution range of the mixed expanded graphite material obtained in the comparative example 1 is 1-150 nm, and the specific surface area is 277m2(ii)/g, expansion factor 101.
Claims (3)
1. A method for preparing mixed expanded graphite from microcrystalline graphite and flake graphite is characterized by comprising the following steps:
s1, ball milling crystalline flake graphite and microcrystalline graphite in a mass ratio of 1:1 until the particle size is 200 meshes, and obtaining a mixture; the carbon content of the flake graphite is not lower than 85%, the microcrystalline graphite is Chenzhou Shandong pond graphite powder, and the carbon content of the microcrystalline graphite is 70-80%; the ball-material ratio in the ball milling process is 6:1, the ball milling time is 6h, and the rotating speed is 500 r/min;
s2, placing the mixture obtained in the step S1 in a muffle furnace, heating to 500 ℃ at the speed of 30 ℃/min under the inert atmosphere, preserving heat for 20min, and cooling to room temperature for later use;
s3, carrying out chemical intercalation treatment on the mixture subjected to the heat treatment of S2 to obtain expandable mixed graphite;
s4, placing the expandable mixed graphite obtained in the step S3 into a muffle furnace to be expanded for 30S at 1000 ℃ to obtain a mixed expanded graphite material;
wherein: the step S3 comprises the following steps:
s31, mixing perchloric acid and the mixed powder obtained in the step S2 according to a liquid-solid ratio of 20: 1L/Kg of the mixture is mixed and stirred evenly;
s32, mixing the mixed powder with potassium permanganate according to a mass ratio of 1: 8, adding potassium permanganate, uniformly stirring at room temperature, heating to 70 ℃, and continuously stirring for reaction for 2 hours;
s33, adding deionized water to raise the temperature in the reaction device to 100 ℃, and continuing stirring for reaction for 2 hours;
s34, filtering, washing and drying the filtered substance to obtain the expandable mixed graphite.
2. The method for preparing mixed expanded graphite from microcrystalline graphite and crystalline flake graphite as claimed in claim 1, wherein the inert atmosphere of step S2 is one of nitrogen and argon.
3. A mixed expanded graphite material produced by the method for producing mixed expanded graphite from microcrystalline graphite and flake graphite according to claim 1 or 2.
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| CN113066981B (en) * | 2021-03-22 | 2022-04-12 | 内蒙古杉杉科技有限公司 | N-doped graphene slurry and graphite material modified by using same |
| CN113753888A (en) * | 2021-10-21 | 2021-12-07 | 青岛洛唯新材料有限公司 | Expandable graphite and preparation method and production system thereof |
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| CN104157863A (en) * | 2014-08-22 | 2014-11-19 | 东莞市长安东阳光铝业研发有限公司 | Preparation method of micro-expansive graphite anode material |
| CN105355870A (en) * | 2015-10-22 | 2016-02-24 | 清华大学深圳研究生院 | Expanded graphite and nano-silicon composite material, preparation method thereof, electrode plate and battery |
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| CN104157863A (en) * | 2014-08-22 | 2014-11-19 | 东莞市长安东阳光铝业研发有限公司 | Preparation method of micro-expansive graphite anode material |
| CN105355870A (en) * | 2015-10-22 | 2016-02-24 | 清华大学深圳研究生院 | Expanded graphite and nano-silicon composite material, preparation method thereof, electrode plate and battery |
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Effective date of registration: 20230113 Address after: 200137 Building 1 and Building 2, No. 333, Haiyang 1st Road, Lingang New Area, China (Shanghai) Pilot Free Trade Zone, Pudong New Area, Shanghai Patentee after: Shanghai Zhicha Technology Co.,Ltd. Address before: 412007 No. 88 Taishan Road, Tianyuan District, Zhuzhou City, Hunan Province Patentee before: HUNAN University OF TECHNOLOGY Effective date of registration: 20230113 Address after: 158100 Yuejin Committee, Mashan District, Jixi City, Heilongjiang Province Patentee after: JIXI ZHONGHUI GRAPHITE PRODUCTS Co.,Ltd. Address before: 200137 Building 1 and Building 2, No. 333, Haiyang 1st Road, Lingang New Area, China (Shanghai) Pilot Free Trade Zone, Pudong New Area, Shanghai Patentee before: Shanghai Zhicha Technology Co.,Ltd. |
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