CN116281996A - Preparation method of high-interlayer-spacing graphite, negative electrode and lithium battery - Google Patents
Preparation method of high-interlayer-spacing graphite, negative electrode and lithium battery Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 146
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 145
- 239000010439 graphite Substances 0.000 title claims abstract description 145
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 18
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 18
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- 239000002253 acid Substances 0.000 claims abstract description 93
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 87
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 80
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 54
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 45
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 45
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 42
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000011229 interlayer Substances 0.000 claims abstract description 39
- 239000007864 aqueous solution Substances 0.000 claims abstract description 8
- 238000006243 chemical reaction Methods 0.000 claims abstract description 7
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 42
- 238000000034 method Methods 0.000 claims description 26
- 239000000243 solution Substances 0.000 claims description 18
- 239000002904 solvent Substances 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 14
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 14
- 239000010410 layer Substances 0.000 abstract description 8
- 238000009830 intercalation Methods 0.000 abstract description 5
- 230000002687 intercalation Effects 0.000 abstract description 5
- 230000002441 reversible effect Effects 0.000 abstract description 3
- 229910052799 carbon Inorganic materials 0.000 abstract 1
- 238000009792 diffusion process Methods 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 23
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- 239000012535 impurity Substances 0.000 description 8
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- 230000009471 action Effects 0.000 description 5
- 239000007772 electrode material Substances 0.000 description 5
- 238000001914 filtration Methods 0.000 description 5
- 238000009831 deintercalation Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
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- 230000008901 benefit Effects 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 239000007800 oxidant agent Substances 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000005119 centrifugation Methods 0.000 description 2
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- 239000007773 negative electrode material Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 1
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- 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
- C01B32/21—After-treatment
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- 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
- C01B32/21—After-treatment
- C01B32/215—Purification; Recovery or purification of graphite formed in iron making, e.g. kish graphite
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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- H—ELECTRICITY
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- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The application relates to a preparation method of high-interlayer-spacing spherical graphite, and high-interlayer-spacing graphite, a negative electrode and a lithium battery. The preparation method of the high-interlayer spacing spherical graphite comprises the following steps: adding spherical graphite into a first acid agent to react to obtain purified graphite, wherein the first acid agent is an aqueous solution comprising hydrochloric acid, nitric acid and hydrofluoric acid; adding the purified graphite into a second acid agent at a second temperature for reaction, wherein the second acid agent is an aqueous solution comprising hydrochloric acid, sulfuric acid and nitric acid; and adding hydrogen peroxide into the second acid agent containing the purified graphite to react, so as to obtain the high-interlayer-spacing graphite. According to the preparation method of the high-interlayer-spacing graphite, under the condition that the granularity of the natural spherical graphite and the diameter of the hexagonal plane of the carbon are not changed obviously, the interlayer spacing is kept in a stretched state, an expansion space is reserved in the natural spherical graphite, a lithium ion diffusion channel is widened, and the collapse of a graphite layer structure caused by the expansion of the lithium intercalation of the graphite is reduced. Although the reversible lithium storage capacity of graphite is not changed greatly, the rate discharge performance and the cycle performance are obviously improved.
Description
Technical Field
The application relates to the field of graphite materials, in particular to a preparation method of high-interlayer-spacing graphite, the high-interlayer-spacing graphite, a corresponding negative electrode and a lithium battery.
Background
The negative electrode material of the existing lithium ion secondary battery is mainly graphite. When the spherical graphite is directly used as a lithium ion battery cathode material, lithium ions are continuously intercalated and deintercalated between graphite sheets, so that the interlayer structure of the graphite sheets is changed, the graphite sheets are easy to peel off, the specific charge capacity of charge and discharge is rapidly attenuated, and the larger the charge and discharge multiplying power is, the more obvious the capacity attenuation phenomenon is.
Disclosure of Invention
The embodiment of the application provides a preparation method of high-interlayer-spacing graphite and the high-interlayer-spacing graphite, so as to solve the technical problem that graphite sheets are easy to peel off in the lithium ion intercalation and deintercalation process.
In a first aspect, an embodiment of the present application provides a method for preparing high-interlayer spacing graphite, including the steps of:
adding spherical graphite into a first acid agent to react to obtain purified graphite, wherein the first acid agent is an aqueous solution, and the first acid agent comprises hydrochloric acid, nitric acid and hydrofluoric acid;
adding the purified graphite into a second acid agent at a second temperature for reaction, wherein the second acid agent is an aqueous solution, and comprises hydrochloric acid with the concentration of not less than 30%, sulfuric acid with the concentration of not less than 80% and nitric acid with the concentration of not less than 68%;
and adding hydrogen peroxide into the second acid agent containing the purified graphite to react, so as to obtain the high-interlayer-spacing graphite.
In some embodiments of the present application, the method for preparing high-interlayer spacing graphite further comprises the steps of:
dispersing the high-interlayer-spacing graphite in a lithium hydroxide solution, taking out the high-interlayer-spacing graphite, and removing the solvent.
In some embodiments of the present application, the lithium hydroxide solution has a concentration of 0.01 to 0.03mol/L.
In some embodiments of the present application, the concentration of hydrochloric acid in the first acid agent is 10% -15%, the concentration of nitric acid is 6.8% -13.6%, and the concentration of hydrofluoric acid is 6.6% -10%; and/or the number of the groups of groups,
in the second acid agent, the concentration of hydrochloric acid is 10-15%, the concentration of sulfuric acid is 26.6-32.6%, and the concentration of nitric acid is 6.8% -13.6%.
In some embodiments of the present application, the concentration of hydrogen peroxide is 35% and the amount added is 50 kg/ton of graphite.
In some embodiments of the present application, the first temperature is 60-80 ℃; and/or the number of the groups of groups,
the second temperature is 45-60 ℃.
In some embodiments of the present application, the treating the spheroidal graphite with a first acid at a first temperature is performed for a time not less than 16 hours; and/or the number of the groups of groups,
adding a second acid agent at a second temperature into the purified graphite to react for a period of time not shorter than 14 hours; and/or the number of the groups of groups,
and adding hydrogen peroxide into the second acid agent containing the purified graphite to react for 15-30min.
In a second aspect, embodiments of the present application provide a high-interlayer-spacing graphite prepared by the above-described method for preparing high-interlayer-spacing graphite.
In a third aspect, embodiments of the present application provide a negative electrode comprising the aforementioned high-interlayer spacing graphite.
In a fourth aspect, embodiments of the present application provide a lithium battery including the foregoing negative electrode.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
the embodiment of the application provides a preparation method of high-interlayer-spacing graphite, the high-interlayer-spacing graphite, a negative electrode and a lithium battery, wherein nitric acid and hydrogen peroxide are used for carrying out layer expansion treatment on spherical graphite, so that the interlayer spacing of a graphite sheet is increased, and the graphite sheet is not easy to fall off in the process of lithium ion intercalation and deintercalation, so that the multiplying power discharge performance and the cycle performance of a corresponding electrode material are increased.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the description of the embodiments or the prior art will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.
Fig. 1 is a schematic flow chart of a method for preparing high-interlayer spacing graphite according to an embodiment of the present application.
Detailed Description
The advantages and various effects of the present application will be more clearly apparent from the following detailed description and examples. Those skilled in the art will appreciate that these specific embodiments and examples are presented to illustrate the application and not to limit the application.
Throughout the specification, unless specifically indicated otherwise, the terms used herein should be understood as meaning as commonly used in the art. Thus, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. In case of conflict, the present specification will control.
Unless specifically indicated otherwise, the various raw materials, reagents, instruments, equipment, and the like used in this application are commercially available or may be prepared by existing methods.
In the conventional graphite, when used as a negative electrode of a lithium ion secondary battery, the graphite sheet layer has the technical problem of easy peeling in the process of lithium ion intercalation and deintercalation.
The technical scheme provided by the embodiment of the application aims to solve the technical problems, and the overall thought is as follows:
in a first aspect, referring to fig. 1, an embodiment of the present application provides a method for preparing high-layer-spacing graphite, including the following steps:
s1: adding spherical graphite into a first acid agent to react to obtain purified graphite, wherein the first acid agent is an aqueous solution, and the first acid agent comprises hydrochloric acid, nitric acid and hydrofluoric acid;
s2: adding the purified graphite into a second acid agent at a second temperature to react with hydrogen peroxide, wherein the second acid agent is an aqueous solution, and comprises hydrochloric acid, sulfuric acid and nitric acid;
s3: and adding hydrogen peroxide into the second acid agent containing the purified graphite to react, so as to obtain the high-interlayer-spacing graphite.
In this application, the interlayer spacing refers to the spacing between graphite flake layers.
In the application, the first acid agent comprises hydrochloric acid, nitric acid and hydrofluoric acid, wherein the hydrochloric acid is used for dissolving Al, ca, K and other impurities in the spherical graphite, the nitric acid is used for acting as a strong oxidant, the purification reaction speed is increased, al, ca, K and other impurities in the spherical graphite are dissolved, and the hydrofluoric acid is used for reacting with Si-containing impurities in the spherical graphite, so that the purity of the spherical graphite is improved.
The proportion of hydrochloric acid, nitric acid and hydrofluoric acid can be adjusted by a person skilled in the art according to the action of each acid agent and the conventional knowledge in the art.
It will be appreciated by those skilled in the art that steps S1 and S2 further include steps of withdrawing the purified graphite and washing the purified graphite. Methods of removing the purified graphite include, but are not limited to, filtration, centrifugation.
It will be appreciated by those skilled in the art that steps S2 and S3 further include steps of filtering out the purified graphite and washing the purified graphite.
In the present application, the second acid agent includes hydrochloric acid, sulfuric acid and nitric acid, wherein the hydrochloric acid acts to dissolve insoluble matters generated in the primary purification process, the nitric acid acts as a strong oxidizer to facilitate expansion of the graphite interlayer spacing, and the sulfuric acid acts to dissolve impurities, which can enter the graphite interstices as a strong protonic acid.
The ratio of hydrochloric acid to sulfuric acid can be adjusted by those skilled in the art based on the action of each acid agent and conventional knowledge in the art.
In the present application, the purpose of adding hydrogen peroxide to the second acid agent is to add a strong oxidizing agent, which acts to enlarge the graphite interlayer spacing.
The addition amount of hydrogen peroxide can be adjusted by a person skilled in the art according to the effect of hydrogen peroxide and conventional knowledge in the art.
In summary, the method can prepare graphite with high interlayer spacing, so that lithium ions are easier to insert and extract, and the phenomenon that graphite sheets are easy to peel off in the process of lithium ion insertion and extraction can be reduced.
In some embodiments of the present application, the method for preparing high-interlayer spacing graphite further comprises the steps of:
s4: dispersing the high-interlayer-spacing graphite in a lithium hydroxide solution, taking out the high-interlayer-spacing graphite, and removing the solvent.
The graphite may be dispersed in the lithium hydroxide solution by means conventional in the art, including but not limited to stirring, sonication.
It is understood by those skilled in the art that the lithium hydroxide solution should be excessive to ensure that the concentration thereof does not fluctuate greatly due to the addition of the high-interlayer graphite, thereby ensuring that the surface coating amount of the lithium hydroxide on the high-interlayer graphite is relatively stable.
Those skilled in the art will appreciate that the methods of removing the purified graphite include, but are not limited to, filtration, centrifugation.
The person skilled in the art can remove the solvent by means conventional in the art, for example oven drying, evaporating to dryness.
Those skilled in the art will appreciate that after dispersing the high-layer spacing graphite in lithium hydroxide, removing the solvent can coat the lithium hydroxide on the surface of the graphite, increasing the total amount of lithium ions and leading the initial coulombic efficiency to be obviously improved. The first coulombic efficiency is defined as the ratio of the discharge capacity to the charge capacity of the lithium ion battery during the first charge-discharge cycle.
In some embodiments of the present application, the lithium hydroxide solution has a concentration of 0.01 to 0.03mol/L.
Those skilled in the art will appreciate that the concentration of the lithium hydroxide solution of 0.01 to 0.03mol/L has the beneficial effects that: part of lithium ions can enter the graphite layer to play a role in prelithiation; the lithium hydroxide solution is strongly alkaline, and can improve the pH value of graphite.
In some embodiments of the present application, the first acid agent has a hydrochloric acid concentration of 10% to 15%, a nitric acid concentration of 6.8% to 13.6%, and a hydrofluoric acid concentration of 6.6% to 10%.
Those skilled in the art will appreciate that the concentration of hydrochloric acid is 10% -15% to enhance the solubility of impurities, the concentration of nitric acid is 6.8% -13.6% to accelerate the reaction rate, and the concentration of hydrofluoric acid is 6.6% -10% to digest poorly soluble impurities.
In some embodiments of the present application, the second acid agent has a hydrochloric acid concentration of 10-15%, a sulfuric acid concentration of 26.6-32.6%, and a nitric acid concentration of 6.8% -13.6%.
In some embodiments of the present application, the concentration of hydrogen peroxide is 35% and the amount added is 50 kg/ton of graphite.
In some embodiments of the present application, the first temperature is 60-80 ℃.
Those skilled in the art will appreciate that the first temperature of 60-80 c has the beneficial effect of increasing the temperature to speed up the reaction and increase the solubility.
In some embodiments of the present application, in step S1, the treating the spheroidal graphite with the first acid agent at the first temperature is performed for a time not less than 16 hours.
It will be appreciated by those skilled in the art that the treatment time is not less than 16 hours, which is advantageous for the first acid to sufficiently decompose and dissolve the impurities in the spheroidal graphite.
In some embodiments of the present application, the second temperature is 45-60 ℃.
It will be appreciated by those skilled in the art that the second temperature of 45-60 c provides the beneficial effect of ensuring the micro-expansion effect of the graphite interlayer spacing while ensuring the impurity removal effect.
In some embodiments of the present application, in step S2, the purified graphite is reacted by adding a second acid agent at a second temperature for a time not less than 14 hours.
Those skilled in the art will appreciate that the reaction time is not shorter than 14 hours, which has the advantage that the longer reaction time can ensure the purification effect of graphite.
In some embodiments of the present application, in step S3, hydrogen peroxide is added to the second acid agent containing the purified graphite to perform a reaction, where the reaction time is 15-30min.
Those skilled in the art will appreciate that the reaction time of 15-30min has the beneficial effect of ensuring the micro-swelling effect between graphite layers and avoiding the influence on the product performance due to overlarge interlayer spacing.
In a second aspect, based on a general inventive concept, embodiments of the present application further provide a high-interlayer-spacing spherical graphite prepared by the above-mentioned method for preparing high-interlayer-spacing graphite. The specific implementation manner of the high-layer-spacing graphite can refer to the above embodiment, and because the high-layer-spacing graphite adopts some or all of the technical solutions of the above embodiment, at least the technical solutions of the above embodiment have all the beneficial effects, and are not described in detail herein.
In a third aspect, embodiments of the present application provide a negative electrode comprising the aforementioned high-interlayer spacing graphite. The negative electrode is realized based on the high-layer-spacing graphite, and the specific implementation can refer to the above embodiment, and because the negative electrode adopts part or all of the technical solutions of the above embodiment, at least has all the beneficial effects brought by the technical solutions of the above embodiment, and the details are not repeated here. In addition, the graphite in the negative electrode has larger interlayer spacing, is not easy to peel off in the process of lithium ion intercalation and deintercalation, and improves the first coulombic efficiency through pre-lithiation, so that the graphite negative electrode material with high first coulombic efficiency and large specific capacity is obtained.
In a fourth aspect, embodiments of the present application provide a lithium battery including the foregoing negative electrode. The rest of the lithium battery may be referred to as known in the art. The lithium battery is realized based on the negative electrode, and the specific implementation of the lithium battery can refer to the above embodiment, and because the lithium battery adopts part or all of the technical solutions of the above embodiment, the lithium battery has at least all the beneficial effects brought by the technical solutions of the above embodiment, and will not be described in detail herein. In addition, since the negative electrode of the lithium battery has high first coulombic efficiency, the lithium battery also has high first coulombic efficiency.
The present application is further illustrated below in conjunction with specific embodiments. It should be understood that these examples are illustrative only of the present application and are not intended to limit the scope of the present application. The experimental procedures, which are not specified in the following examples, are generally determined according to national standards. If the corresponding national standard does not exist, the method is carried out according to the general international standard, the conventional condition or the condition recommended by the manufacturer.
Example 1
The embodiment provides a preparation method of high-interlayer spacing graphite, which comprises the following steps:
sa: adding 500g of spherical graphite with purity of 90-95% into 750g of first acid agent, reacting for 16h at 70 ℃, filtering to obtain purified graphite, and washing the purified graphite;
sb: adding the purified graphite into 500g of a second acid agent, and reacting for 14h at 60 ℃;
sc: adding 35% hydrogen peroxide into the second acid agent, maintaining the temperature of 60 ℃ for reaction for 30min, filtering to obtain filter residues, and washing the filter residues;
sd: adding the filter residue into 1000mL (the excessive amount is ensured here) of lithium hydroxide solution with the concentration of 0.01mol/L, stirring for 2h, centrifuging to obtain a solid, and drying to obtain the high-interlayer spacing graphite.
In step Sa, the first acid agent is composed of hydrochloric acid, nitric acid, hydrofluoric acid, and water. Wherein the concentration of hydrochloric acid in the first acid agent is 10%, the concentration of nitric acid in the first acid agent is 6.8%, and the concentration of hydrofluoric acid in the first acid agent is 9%.
In step Sb, the second acid agent is composed of hydrochloric acid, sulfuric acid, nitric acid, and water. Wherein the concentration of hydrochloric acid in the second acid agent is 12%, the concentration of sulfuric acid in the second acid agent is 28%, and the concentration of nitric acid in the second acid agent is 11%.
In the step Sc, the adding amount of hydrogen peroxide is 25g.
The embodiment also provides the high-interlayer spacing graphite prepared by the method.
Example 2
This embodiment differs from embodiment 1 only in that:
in step Sa, the first acid agent is composed of hydrochloric acid, nitric acid, hydrofluoric acid, and water. Wherein the concentration of hydrochloric acid in the first acid agent is 10%, the concentration of nitric acid in the first acid agent is 6.8%, and the concentration of hydrofluoric acid in the first acid agent is 6.6%.
In step Sb, the second acid agent is composed of an acid, sulfuric acid, nitric acid, and water. Wherein the concentration of hydrochloric acid in the second acid agent is 12%, the concentration of sulfuric acid in the second acid agent is 26.6%, and the concentration of nitric acid in the second acid agent is 6.8%.
In the step Sc, the addition amount of hydrogen peroxide is 12.5g.
Example 3
This embodiment differs from embodiment 1 only in that:
in step Sa, the first acid agent is composed of hydrochloric acid, nitric acid, hydrofluoric acid, and water. Wherein the concentration of hydrochloric acid in the first acid agent is 15%, the concentration of nitric acid in the first acid agent is 6.8%, and the concentration of hydrofluoric acid in the first acid agent is 9%.
In step Sb, the second acid agent is composed of an acid, sulfuric acid, nitric acid, and water. Wherein the concentration of hydrochloric acid in the second acid agent is 15%, the concentration of sulfuric acid in the second acid agent is 32%, and the concentration of nitric acid in the second acid agent is 13.6%.
In the step Sc, the adding amount of hydrogen peroxide is 50g.
Example 4
In step Sa, the first acid agent is composed of hydrochloric acid, nitric acid, hydrofluoric acid, and water. Wherein the concentration of hydrochloric acid in the first acid agent is 10%, the concentration of nitric acid in the first acid agent is 6.8%, and the concentration of hydrofluoric acid in the first acid agent is 9%.
In step Sb, the second acid agent is composed of hydrochloric acid, sulfuric acid, nitric acid, and water. Wherein the concentration of hydrochloric acid in the second acid agent is 12%, the concentration of sulfuric acid in the second acid agent is 28%, and the concentration of nitric acid in the second acid agent is 12%.
In the step Sc, the adding amount of hydrogen peroxide is 37.5g.
Example 5
In step Sa, the first acid agent is composed of hydrochloric acid, nitric acid, hydrofluoric acid, and water. Wherein the concentration of hydrochloric acid in the first acid agent is 10%, the concentration of nitric acid in the first acid agent is 6.8%, and the concentration of hydrofluoric acid in the first acid agent is 9%.
In step Sb, the second acid agent is composed of an acid, sulfuric acid, nitric acid, and water. Wherein the concentration of hydrochloric acid in the second acid agent is 12%, the concentration of sulfuric acid in the second acid agent is 30%, and the concentration of nitric acid in the second acid agent is 11%.
In the step Sc, the adding amount of hydrogen peroxide is 37.5g.
Comparative example 1
This comparative example differs from example 1 only in that:
in step Sb, the second acid agent is composed of hydrochloric acid, nitric acid, and water. Wherein the concentration of hydrochloric acid in the second acid agent is 12%, and the concentration of nitric acid in the second acid agent is 11%.
Comparative example 2
This comparative example differs from example 1 only in that:
hydrogen peroxide is not added.
Comparative example 3
This comparative example differs from example 1 only in that:
adding hydrogen peroxide, and keeping the reaction time at 60 ℃ for 2 hours.
XRD testing is carried out on the graphite product obtained in the example 1 and the graphite product obtained in the comparative example 1-2, and the lattice spacing is calculated;
the high-interlayer spacing graphite of examples 1-5, the graphite products of comparative examples 1-2 were subjected to Raman testing, and I was calculated D /I G ；
The results of the above tests are shown in Table 1. Table 1 is as follows:
TABLE 1
Wherein I is D /I G Can be used to characterize the graphitization degree of graphite, wherein I represents the Intensity, D represents the defect of the C atom lattice, G represents the in-plane vibration of the C atom sp2 hybridization, I D /I G The larger the number, the more defects representing C atom crystals.
As can be seen from table 1, the high-interlayer spacing graphite provided in example 1 has a significantly increased lattice spacing compared to comparative example 1, indicating that the addition of nitric acid to Sb in example 1 effectively increases the interlayer spacing of the graphite. The higher layer spacing graphite provided in example 1 has an increased lattice spacing compared to comparative example 2, illustrating that the preparation method of example 1 has better effect of increasing lattice spacing than comparative example 2 by adding hydrogen peroxide in step Sc.
As can be seen from Table 1, the high-interlayer spacing graphite provided in example 1 compares with comparative example 1, I D /I G The significant increase, which illustrates the increased degree of disorder of the graphite of example 1, indicates that the addition of nitric acid to Sb in example 1 results in a more significant change in the lattice structure of the graphite compared to comparative example 1. The high-interlayer spacing graphite provided in example 1 compares to comparative example 2, I D /I G An increase, which indicates a trueThe addition of hydrogen peroxide in step Sc of example 1 makes it possible to change the lattice structure of graphite compared to comparative example 2.
As can be seen from Table 1, the high-interlayer spacing graphite provided in example 1 has an increased lattice spacing, I, compared to comparative example 3 D /I G The reaction time of hydrogen peroxide increases, and the lattice spacing and disorder degree increase.
Button half-cells were prepared by taking the high-interlayer spacing graphite of example 1 and the graphite products obtained in comparative examples 1-2 as electrode materials. The preparation method comprises the following steps:
according to 96:1:1.2:1.8 mixing active material, conductive carbon black, CMC and SBR uniformly, coating on copper foil uniformly, vacuum drying at 100deg.C for 6 hr, adjusting compaction density by roll squeezer, cutting off offset material with phi 12mm as working electrode of battery, using metal lithium sheet as counter electrode, and electrolyte of 1mol/L LiPF 6 Ec+emc+dmc (1:1:1, wt.), the separator was assembled into a half-cell of the CR2032 type using Celgard 2400 in an argon-filled glove box.
The button half-cell was subjected to constant current charge and discharge test at a current density of 0.5C, and the reversible specific capacity Qs was measured and calculated, and the reversible specific capacity Qs after 100 and 300 cycles was shown in table 2. Table 2 is as follows:
as can be seen from table 2, compared with comparative example 1, the button half cell provided in example 1 has significantly increased qs, which indicates that the cycle performance of the button half cell of example 1 is significantly improved, and further indicates that the preparation method of example 1 can significantly improve the cycle performance of the corresponding electrode material by increasing the spacing between graphite sheets. The increased qs of the high-interlayer spacing graphite provided in example 1 compared to comparative example 2 demonstrates that the cycling performance of the button half cell of example 1 is improved, and further demonstrates that the preparation method of example 1 can more significantly improve the cycling performance of the corresponding electrode material compared to comparative example 2. Compared with the embodiment 1, the Qs of the comparative example 3 is obviously reduced, which indicates that the cycle performance of the button half cell of the comparative example 3 is reduced, and further indicates that the preparation method of the comparative example 3, namely, the too long hydrogen peroxide reaction time can cause the overlarge spacing of graphite sheets so as to influence the cycle performance of the electrode material. The Qs is reduced after 100 circles and 300 circles of the same sample are circulated, but the reduction of the amplitude is reduced along with the expansion of the interlayer spacing of the graphite, the reduction of the amplitude of 100 circles is 95-97%, and the reduction of the amplitude of 300 circles is 90-93%.
Various embodiments of the present application may exist in a range format; it should be understood that the description in a range format is merely for convenience and brevity and should not be interpreted as a rigid limitation on the scope of the application. It is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.
In this application, unless otherwise indicated, terms of orientation such as "upper" and "lower" are used specifically to refer to the orientation of the drawing in the figures. In addition, in the description of the present application, the terms "include", "comprise", "comprising" and the like mean "including but not limited to". Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element. Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Herein, "and/or" describing an association relationship of an association object means that there may be three relationships, for example, a and/or B, may mean: a alone, a and B together, and B alone. For the association relation of more than three association objects described by the "and/or", it means that any one of the three association objects may exist alone or any at least two of the three association objects exist simultaneously, for example, for a, and/or B, and/or C, any one of the A, B, C items may exist alone or any two of the A, B, C items exist simultaneously or three of the three items exist simultaneously. Herein, "at least one" means one or more, and "a plurality" means two or more. "at least one", "at least one" or the like refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
The foregoing is merely a specific embodiment of the application to enable one skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The preparation method of the high-interlayer-spacing graphite is characterized by comprising the following steps of:
adding spherical graphite into a first acid agent to react to obtain purified graphite, wherein the first acid agent is an aqueous solution, and the first acid agent comprises hydrochloric acid, nitric acid and hydrofluoric acid;
adding the purified graphite into a second acid agent at a second temperature for reaction, wherein the second acid agent is an aqueous solution, and comprises hydrochloric acid, sulfuric acid and nitric acid;
and adding hydrogen peroxide into the second acid agent containing the purified graphite to react, so as to obtain the high-interlayer-spacing graphite.
2. The method for producing high-interlayer spacing graphite according to claim 1, further comprising the steps of:
dispersing the high-interlayer-spacing graphite in a lithium hydroxide solution, taking out the high-interlayer-spacing graphite, and removing the solvent.
3. The method for producing high-interlayer spacing graphite according to claim 2, wherein the concentration of the lithium hydroxide solution is 0.1 to 0.5mol/L.
4. The method for producing high-interlayer spacing graphite according to claim 1, wherein,
the concentration of hydrochloric acid is 10% -15%, the concentration of nitric acid is 6.8% -13.6%, and the concentration of hydrofluoric acid is 6.6% -10%; and/or the number of the groups of groups,
in the second acid agent, the concentration of hydrochloric acid is 10-15%, the concentration of sulfuric acid is 26.6-32.6%, and the concentration of nitric acid is 6.8% -13.6%.
5. The method for preparing high-interlayer spacing graphite according to claim 1, wherein the concentration of hydrogen peroxide is 35%, and the addition amount is 50 kg/ton of graphite.
6. The method for producing high-interlayer spacing graphite according to claim 1, wherein,
the first temperature is 60-80 ℃; and/or the number of the groups of groups,
the second temperature is 35-45 ℃.
7. The method for producing high-interlayer spacing graphite according to claim 1, wherein,
the spherical graphite is treated by a first acid agent at a first temperature, and the treatment time is not shorter than 16 hours; and/or the number of the groups of groups,
adding a second acid agent at a second temperature into the purified graphite to react for a period of time not shorter than 14 hours; and/or the number of the groups of groups,
and adding 35% hydrogen peroxide into the second acid agent containing the purified graphite to react for 30-60min.
8. A high-interlayer graphite prepared by the method of any one of claims 1 to 7.
9. A negative electrode comprising the high-interlayer spacing graphite of claim 8.
10. A lithium battery comprising the negative electrode of claim 9.
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