CN113611851B - Lithium ion battery material and preparation method thereof by adopting super-assembly and dealloying - Google Patents

Lithium ion battery material and preparation method thereof by adopting super-assembly and dealloying Download PDF

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CN113611851B
CN113611851B CN202110941716.1A CN202110941716A CN113611851B CN 113611851 B CN113611851 B CN 113611851B CN 202110941716 A CN202110941716 A CN 202110941716A CN 113611851 B CN113611851 B CN 113611851B
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lithium ion
ion battery
dealloying
battery material
assembly
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CN113611851A (en
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孔彪
李东玮
谢磊
高翔
姜晓萍
李勇
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Fudan University
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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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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
    • 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
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • 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
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention belongs to the technical field of lithium battery materials, and provides a lithium ion battery material and a preparation method thereof by adopting super-assembly and dealloying, wherein a ternary alloy containing metal Al, Co and Ni is placed in a hydrogen peroxide solution, and a strong alkaline solution is added for dealloying reaction; then adding aminopropyl trimethoxy silane, and performing ultrasonic treatment for a period of time to obtain a precursor; preparing graphene oxide powder into graphene oxide dispersion liquid, mixing the graphene oxide dispersion liquid with the precursor according to a certain mass ratio, and then adding ammonia water and citric acid to obtain a material intermediate; and finally, heating the material intermediate to a certain temperature in a preset atmosphere, preserving the heat for a certain time, and then cooling to room temperature to obtain the lithium ion battery material. The composite of the oxide and the graphene can integrate the advantages of two components and improve the electrochemical performance of a single material.

Description

Lithium ion battery material and preparation method thereof by adopting super-assembly and dealloying
Technical Field
The invention belongs to the technical field of lithium battery materials, and particularly relates to a lithium ion battery material and a preparation method thereof by adopting super-assembly and dealloying.
Background
In the technical field of lithium ion batteries, the current commercial negative electrode materials are mainly graphite materials, however, the graphite materials have a plurality of disadvantages, such as: the theoretical specific capacity is low; the service life is short; the first charge-discharge efficiency is low; poor thermal stability, etc.
Compared with graphite material, the transition metal oxide is uniqueThe lithium storage mechanism of (a) can exhibit a relatively high reversible specific capacity and is a research hotspot. Wherein, Co 3 O 4 The NiO lithium storage capacity has high specific capacity, and both the NiO lithium storage capacity and the NiO lithium storage capacity are metal oxide negative electrode materials which are researched more at present. However, the diffusion coefficients of electrons and ions of the two metal oxides are not large, so that the cycle performance and the conductive performance of the metal oxides are poor.
At present, researches prove that the nano-material is one of effective ways for solving the problems. The nano material has the characteristics of large specific surface area, short ion embedding and extracting path and the like, weakens the polarization degree of an electrode during charging and discharging, inhibits the volume change caused in the lithium extracting process, and improves the reversible capacity and the cycle capacity. But the nanoparticles are prone to agglomeration. However, the nano material with special morphology can prevent agglomeration, keep the stable structure of the nano material in circulation and improve the circulation performance. In addition, the special morphology can also improve the contact area of electrode and electrolyte, shortens the diffusion distance of lithium ion and electron, provides extra lithium ion storage space. Although it is currently about the preparation of nano Co 3 O 4 And NiO, but these methods are generally more complex and have poor controllability, and the prepared Co is not suitable for use as a cathode material of a battery 3 O 4 And NiO are not very functional in lithium ion batteries. Therefore, the development of a preparation method of a battery anode material with simple operation and good controllability is urgently needed.
Disclosure of Invention
The present invention is made to solve the above problems, and an object of the present invention is to provide a lithium ion battery material and a method for preparing the same by super-assembly and dealloying.
The invention provides a method for preparing a lithium ion battery material by adopting super-assembly and dealloying, which is characterized by comprising the following steps: step S1, placing the ternary alloy in a hydrogen peroxide solution, adding a strong alkali solution into the hydrogen peroxide solution, and performing dealloying reaction at a preset temperature to obtain a dealloyed material; step S2, placing the dealloying material in ethanol, performing ultrasonic treatment for a period of time, adding aminopropyl trimethoxysilane, and performing ultrasonic treatment for a period of time to obtain a precursor; step S3, preparing graphene oxide powder into graphene oxide dispersion liquid, and mixing the precursor and the graphene oxide dispersion liquid according to a certain mass ratio to obtain a mixed solution; step S4, adding ammonia water into the mixed solution, stirring for reaction, adding citric acid, and continuously stirring at a certain temperature to obtain a material intermediate; step S5, heating the material intermediate to a certain temperature in a preset atmosphere, preserving heat for a certain time, and cooling to room temperature to obtain the lithium ion battery material, wherein in step S1, the components of the ternary alloy comprise metal Al, Co and Ni; in the step S3, the mass ratio of the precursor to the graphene oxide is 20-30: 1.
the method for preparing the lithium ion battery material by adopting the super-assembly and the dealloying can also have the following characteristics: in the step S1, the atomic percent of Al in the ternary alloy sheet is 70-90%; the percentage of total atoms of Co/Ni alloy in the ternary alloy sheet is 10-30%; the atomic percent of Co in the Co/Ni alloy is more than 0 and less than 100 percent;
the method for preparing the lithium ion battery material by adopting the super-assembly and the dealloying can also have the following characteristics: in step S1, the atomic percent of Al in the ternary alloy sheet is 80%; the total atomic percent of the Co/Ni alloy in the ternary alloy sheet is 20%; the Co/Ni alloy contains 25, 50, or 75 atomic% of Co.
The method for preparing the lithium ion battery material by adopting the super-assembly and the dealloying can also have the following characteristics: wherein, in step S4, a purification step is further included; the purification steps are specifically as follows: taking the material intermediate, washing the material intermediate with water until the pH value of the supernatant is 7, and then performing vacuum drying at 60 ℃ for 12h to obtain the purified material intermediate, wherein the purified material intermediate is used in step S5 at a preset temperature in an atmosphere.
The method for preparing the lithium ion battery material by adopting the super-assembly and the dealloying can also have the following characteristics: in step S1, the strong alkali solution is a sodium hydroxide solution or a potassium hydroxide solution; the amount of the substance of the strong alkali solution is 100 times of the equivalent of the dealloying reaction; the concentration of hydrogen peroxide is 3.0-9.8M; the concentration of the strong alkali solution is 0.1-6M; in the step S2, the aminopropyl trimethoxysilane is 0.5-2 mL; step S4, ammonia water is 50-100 muL; the citric acid is 30-100 mg.
The method for preparing the lithium ion battery material by adopting the super-assembly and the dealloying can also have the following characteristics: in step S1, the preset temperature is 25-60 ℃; the dealloying reaction time is 2-12 h; in step S6, the certain temperature is 300-600 ℃; the certain time is 5-10 h.
The method for preparing the lithium ion battery material by adopting the super-assembly and the dealloying can also have the following characteristics: in step S6, the predetermined atmosphere is any one of argon, nitrogen, or a mixed gas of hydrogen and argon.
The method for preparing the lithium ion battery material by adopting the super-assembly and the dealloying can also have the following characteristics: in step S6, the argon in the mixed gas is high-purity argon having a purity of not less than 99.9%.
The method for preparing the lithium ion battery material by adopting the super-assembly and the dealloying can also have the following characteristics: in step S6, the volume content of hydrogen in the mixed gas is 5% to 10%.
The invention also provides a lithium ion battery material, which has the following characteristics: the lithium ion battery material is any one of a micron-sized dendritic material formed by using nanosheets as basic units, an irregular composite material with a nanosheet and graphene lamellar structure or a nanoparticle close-packed material formed by using nanorods as basic units; the diameter of the nanosheet is 100 nm; the length of the micron branch is 3-4 mu m; the diameter of the nano rod is 5nm, and the length of the nano rod is 30 nm; the size of the nanoparticles is 300 nm.
Action and Effect of the invention
According to the method for preparing the lithium ion battery material by adopting the super-assembly and the dealloying, disclosed by the invention, the controllable preparation of the high-activity composite metal oxide/graphene nano composite material is realized by freely corroding in a strong electrolyte solution and utilizing the electrostatic adsorption effect between the oxide and graphite oxide by combining the super-assembly method. The material prepared by the method has controllable components and structure, zero loss of the target material and suitability for large-scale production. The composite of the oxide and the graphene can integrate the advantages of two components and improve the electrochemical performance of a single material.
The lithium ion battery material obtained by the invention is any one of micron-scale dendritic materials formed by nano sheets serving as basic units, irregular composite materials formed by nano sheets and graphene sheet layer structures or nano particle close-packed materials formed by nano rods serving as basic units, and is a micron material formed by nano materials serving as basic units, namely a micro-nano structure. The nano material has high surface activation energy and large specific surface area, and can improve the lithium storage capacity when used as a lithium ion battery material; the micron material has the characteristics of high tap density, good stability and easy preparation. The lithium ion battery material obtained by the invention is used as a lithium ion battery cathode material, takes the nano-sheet or nano-rod as a basic unit, has high specific surface area and abundant active sites, and can improve the diffusion rate of lithium ions; the integral micron-sized dendritic structure can prevent the nano sheets from agglomerating, effectively relieve the volume expansion caused by the lithium ions in the de-intercalation process and improve the circulation stability of the material.
Drawings
Fig. 1 is a Scanning Electron Micrograph (SEM) and an energy spectrum analysis (EDS) of the lithium ion battery material prepared in example 1 of the present invention;
fig. 2 is a graph of test data for cells made from the lithium ion battery material prepared in example 1 of the present invention;
fig. 3 is a Scanning Electron Micrograph (SEM) of the lithium ion battery material prepared in example 12 of the present invention;
fig. 4 is a graph of test data for cells made from the lithium ion battery material prepared in example 12 of the present invention;
fig. 5 is a Scanning Electron Micrograph (SEM) of the lithium ion battery material prepared in example 13 of the present invention; and
fig. 6 is a graph of test data for a cell made from the lithium ion battery material prepared in example 13 of the present invention.
Detailed Description
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the lithium ion battery material and the preparation method thereof adopting the super-assembly and the dealloying are specifically described below with reference to the embodiment and the attached drawings.
In the examples of the present invention, the reagents and raw materials were purchased from commercial sources except the materials which were prepared in the laboratory.
The invention relates to a method for preparing a lithium ion battery material by adopting super-assembly and dealloying, which comprises the following steps:
step S1, including the components: and placing the ternary alloy of the metals Al, Co and Ni in a hydrogen peroxide solution, adding a strong alkali solution into the hydrogen peroxide solution, and performing dealloying reaction at a preset temperature to obtain the dealloying material.
In the step, the atomic percent of Al in the ternary alloy is 70-90%, the total atomic percent of Co/Ni alloy in the ternary alloy sheet is 10-30%, and the atomic percent of Co in the Co/Ni alloy is more than 0 and less than 100%. Preferably, the atomic percent of Al in the ternary alloy is 75-80%, and the atomic ratio of Co to Ni in the ternary alloy is 1: 3-3: 1.
In the step, the concentration of the hydrogen peroxide is 3M to 9.8M, and preferably, the concentration of the hydrogen peroxide is 3M to 5M.
In this step, the alkali solution is a sodium hydroxide solution or a potassium hydroxide solution, and the concentration of the alkali solution is 0.1M to 6M, preferably 1M to 2M. The amount of the substance of the strong alkaline solution is 100 times of the equivalent of the dealloying reaction.
In the step, the preset temperature is 25-60 ℃, and the dealloying reaction time is 2-12 h. Preferably, the predetermined temperature is 25 ℃ and the dealloying reaction time is 8 h.
And step S2, placing the dealloying material in ethanol, adding aminopropyl trimethoxy silane after ultrasonic treatment for a period of time, and then performing ultrasonic treatment for a period of time to obtain a precursor.
In this step, the amount of aminopropyltrimethoxysilane solution is 0.5 to 2mL, preferably 1 to 2 mL.
And step S3, preparing graphene oxide powder into graphene oxide dispersion liquid, and mixing the precursor and the graphene oxide dispersion liquid according to a certain mass ratio to obtain a mixed solution.
In the step, the mass ratio of the precursor to the graphene oxide is 20-30: 1, preferably, the mass ratio of the precursor to the graphene oxide is 25-30: 1.
and step S4, adding ammonia water into the mixed solution, stirring for reaction, adding citric acid, and continuously stirring at a certain temperature to obtain a material intermediate.
In this step, the ammonia amount is 50 to 100. mu.L, preferably 50 to 60. mu.L, and the citric acid amount is 30 to 100mg, preferably 50 to 60 mg.
In this step, a purification step may be further included, and the purification step specifically includes: the intermediate material was taken, washed with water to give a supernatant having a pH of 7, and then vacuum-dried at 60 ℃ for 12 hours to obtain a purified intermediate material, which was used in step S5 at elevated temperature in a predetermined atmosphere.
And step S5, heating the material intermediate to a certain temperature in a preset atmosphere, preserving the heat for a certain time, and cooling to room temperature to obtain the lithium ion battery material.
In the step, the preset atmosphere is any one of argon, nitrogen or a mixed gas of hydrogen and argon, the argon in the mixed gas is high-purity argon with the purity not less than 99.9%, and the volume content of the hydrogen in the mixed gas is 5-10%.
In the step, the certain temperature is 300-600 ℃, preferably the certain temperature is 300-500 ℃, and the certain time is 5-10 h, preferably the certain time is 6-10 h.
< example 1>
Step S1, mixing 1g Co 5 Ni 15 Al 80 The alloy sheet is put into 10mL hydrogen peroxide solution (3M)And adding 100mL of sodium hydroxide solution (2M), magnetically stirring at the rotating speed of 2000rpm, and freely corroding at room temperature of 25 ℃ for 8 hours to obtain a corroded dealloyed material.
And step S2, taking 0.2g of corroded dealloyed material, placing the dealloyed material in 50mL of ethanol, performing ultrasonic treatment for 30min, adding 1mL of aminopropyl trimethoxysilane, performing ultrasonic treatment for 30min, stirring for 1h, centrifuging, and cleaning with ultrapure water for 3 times to obtain a precursor.
Step S3, preparing graphene oxide powder by using a hummers method, adding 20mg of graphene oxide into 40mL of ultrapure water, and performing ultrasonic treatment for 1h to prepare a graphene oxide dispersion liquid. And (4) mixing the precursor obtained in the step (S2) with the graphene oxide solution, and magnetically stirring for 1h at the temperature of 25 ℃ and the rotating speed of 2000rpm to obtain a mixed solution.
Step S4, adding 50 μ L of ammonia water to the mixed solution prepared in step S3, magnetically stirring at 25 ℃, 2000rpm for 0.5h, then adding 50mg of citric acid, magnetically stirring at 80 ℃, 2000rpm for 12h to obtain a material intermediate, repeatedly washing with water until the pH of the supernatant becomes 7, and then vacuum-drying at 60 ℃ for 12 h.
And step S5, heating the precursor obtained in the step S4 to 300 ℃ at the speed of 5 ℃/min in argon, preserving the temperature for 6h, and naturally cooling to room temperature to obtain the lithium ion battery material.
Fig. 1 (a), (b) are Scanning Electron Micrographs (SEM) of the lithium ion battery material prepared in example 1.
The lithium ion battery material prepared in this example was subjected to morphology analysis, and the results are shown in fig. 1 (a), (b). As shown in fig. 1 (a), the whole prepared lithium ion battery material has a micron-sized dendritic structure and a length of 3-4 μm; the dendritic structure was enlarged, and as shown in fig. 1 (b), the nanoplatelets were densely packed and had a diameter of 100 nm.
Fig. 1 (c) is an energy spectrum analysis (EDS) of the lithium ion battery material prepared in example 1.
The lithium ion battery material prepared in this example was subjected to energy spectrum analysis, and as a result, as shown in fig. 1 (c), the atomic ratio of Ni and Co was close to 1:2, and it was determined by elemental analysis that the ratio of Ni and Co in the prepared lithium ion battery material was close to 1:2, which was consistent with the ratio of Ni and Co in the precursor. Residual Al is almost undetectable in the dealloyed product according to the dealloying mechanism.
The lithium ion battery material prepared in the embodiment, super P and sodium carboxymethyl cellulose (CMC) are prepared into an electrode slice according to the mass ratio of 7:2:1, and LiFP is adopted 6 And (3) an EC/DMC (V/V ═ 1:1) type electrolyte and a Li sheet are used as counter electrodes to assemble the button cell.
FIG. 2 (a) is a graph showing the first three-cycle charge/discharge of a battery having a current density of 100 mA/g.
As shown in fig. 2 (a), the specific discharge capacities of the first two times were 1245mAh/g and 988mAh/g, respectively, and this irreversible capacity loss was mainly due to decomposition of the electrolyte and formation of the SEI film.
FIG. 2 (b) is a graph showing the cycle characteristics of the battery having a current density of 100 mA/g. As shown in FIG. 2 (b), the discharge capacity after 100 cycles was as high as 1050 mAh/g.
Fig. 2 (c) is a rate performance diagram of the battery. As shown in fig. 2 (c), after different current density charge-discharge cycles, the material has good rate performance and can ensure that the material structure is not damaged in the process of multiple rapid charge-discharge.
< example 2>
On the basis of example 1, the differences are:
in step S1, the etching solution is freely etched for 2h at room temperature and 25 ℃.
< example 3>
On the basis of example 1, the differences are:
in step S1, free etching is carried out at room temperature of 25 ℃ for 12 h.
< example 4>
On the basis of example 1, the differences are:
in step S1, the etching solution is freely etched for 8h at 60 ℃.
< example 5>
On the basis of example 1, the differences are:
in step S5, the temperature is raised to 500 ℃ at the speed of 5 ℃/min in argon, and the temperature is kept for 6 h.
< example 6>
On the basis of example 1, the differences are:
in step S5, the temperature is raised to 600 ℃ at the speed of 5 ℃/min in argon, and the temperature is kept for 6 h.
< example 7>
On the basis of example 1, the differences are:
in step S5, the temperature is raised to 300 ℃ at a rate of 5 ℃/min in argon, and the temperature is maintained for 5 h.
< example 8>
On the basis of example 1, the differences are:
in step S5, the temperature is raised to 300 ℃ at a rate of 5 ℃/min in argon, and the temperature is maintained for 8 h.
< example 9>
On the basis of example 1, the differences are:
in step S5, the temperature is raised to 300 ℃ at a rate of 5 ℃/min in argon, and the temperature is maintained for 10 h.
< example 10>
On the basis of example 1, the differences are:
in step S5, the temperature is raised to 300 ℃ at the speed of 5 ℃/min in argon, and the temperature is maintained for 8 h.
< example 11>
On the basis of example 1, the differences are:
in step S5, Ar/H containing 5% hydrogen gas by volume is added 2 Heating to 300 ℃ at the speed of 5 ℃/min, and keeping the temperature for 6 h.
< example 12>
Step S1, mixing 1gCo 10 Ni 10 Al 80 And (3) placing the alloy sheet into 10mL of hydrogen peroxide solution (3M), adding 100mL of sodium hydroxide solution (2M), magnetically stirring at the rotating speed of 2000rpm, and freely corroding at the room temperature of 25 ℃ for 8 hours to obtain a corroded dealloyed material.
And step S2, taking 0.2g of corroded dealloyed material, placing the dealloyed material in 50mL of ethanol, performing ultrasonic treatment for 30min, adding 1mL of aminopropyl trimethoxysilane, performing ultrasonic treatment for 30min, stirring for 1h, centrifuging, and cleaning with ultrapure water for 3 times to obtain a precursor.
Step S3, preparing graphene oxide powder by using a hummers method, adding 20mg of graphene oxide into 40mL of ultrapure water, and performing ultrasonic treatment for 1h to prepare a graphene oxide dispersion liquid. And (4) mixing the precursor obtained in the step (S2) with the graphene oxide solution, and magnetically stirring for 1h at the temperature of 25 ℃ and the rotating speed of 2000rpm to obtain a mixed solution.
Step S4, adding 50 μ L of ammonia water to the mixed solution prepared in step S3, magnetically stirring at 25 ℃, 2000rpm for 0.5h, then adding 50mg of citric acid, magnetically stirring at 80 ℃, 2000rpm for 12h to obtain a material intermediate, repeatedly washing with water until the pH of the supernatant becomes 7, and then vacuum-drying at 60 ℃ for 12 h.
And step S5, heating the precursor obtained in the step S4 to 300 ℃ at the speed of 5 ℃/min in argon, preserving the temperature for 6h, and naturally cooling to room temperature to obtain the lithium ion battery material.
Fig. 3 (a), (b) are Scanning Electron Micrographs (SEM) of the lithium ion battery material prepared in example 12.
The morphology analysis of the lithium ion battery material prepared in this example was performed, and the results are shown in (a) and (b) in fig. 3, and the prepared lithium ion battery material had a graphene lamellar structure, with a diameter of 100nm and a close-packed nanosheet as a whole.
The lithium ion battery material prepared in the embodiment, super P and sodium carboxymethyl cellulose (CMC) are prepared into an electrode slice according to the mass ratio of 7:2:1, and LiFP is adopted 6 And (3) an EC/DMC (V/V ═ 1:1) type electrolyte and a Li sheet are used as counter electrodes to assemble the button cell.
FIG. 4 (a) is a graph showing the cycle characteristics of a battery having a current density of 100 mA/g.
As shown in FIG. 4 (a), the first-turn capacity was 1550mAh/g, and the discharge capacity after 100 turns was 800 mAh/g.
Fig. 4 (b) is a rate performance diagram of the battery.
As shown in fig. 4 (b), after different current density charge-discharge cycles, the material has good rate performance and can ensure that the material structure is not damaged in the process of multiple rapid charge-discharge.
< example 13>
Step S1, mixing 1g Co 15 Ni 5 Al 80 Alloy pieces are placed in 10mLAnd adding 100mL of sodium hydroxide solution (2M) into hydrogen peroxide solution (3M), magnetically stirring at the rotating speed of 2000rpm, and freely corroding at room temperature of 25 ℃ for 8 hours to obtain a corroded dealloyed material.
And step S2, taking 0.2g of corroded dealloyed material, placing the dealloyed material in 50mL of ethanol, performing ultrasonic treatment for 30min, adding 1mL of aminopropyl trimethoxysilane, performing ultrasonic treatment for 30min, stirring for 1h, centrifuging, and cleaning with ultrapure water for 3 times to obtain a precursor.
Step S3, preparing graphene oxide powder by using a hummers method, adding 20mg of graphene oxide into 40mL of ultrapure water, and performing ultrasonic treatment for 1h to prepare a graphene oxide dispersion liquid. And (4) mixing the precursor obtained in the step (S2) with the graphene oxide solution, and magnetically stirring for 1h at the temperature of 25 ℃ and the rotating speed of 2000rpm to obtain a mixed solution.
Step S4, adding 50 μ L of ammonia water to the mixed solution prepared in step S3, magnetically stirring at 25 ℃, 2000rpm for 0.5h, then adding 50mg of citric acid, magnetically stirring at 80 ℃, 2000rpm for 12h to obtain a material intermediate, repeatedly washing with water until the pH of the supernatant becomes 7, and then vacuum-drying at 60 ℃ for 12 h.
And step S5, heating the precursor obtained in the step S4 to 300 ℃ at the speed of 5 ℃/min in argon, preserving the temperature for 6h, and naturally cooling to room temperature to obtain the lithium ion battery material.
Fig. 5 (a), (b) are Scanning Electron Micrographs (SEM) of the lithium ion battery material prepared in example 13.
The morphology analysis of the lithium ion battery material prepared in this example was performed, and the result is shown in fig. 5 (a), where the whole lithium ion battery material prepared was in a particle-dense packing with a size of-300 nm; after the particles were enlarged, as shown in FIG. 5 (b), the nano-rods were found to be stacked, with a diameter of 5nm and a length of 30 nm.
The lithium ion battery material prepared in the embodiment, super P and sodium carboxymethyl cellulose (CMC) are prepared into an electrode slice according to the mass ratio of 7:2:1, and LiFP is adopted 6 And (3) an EC/DMC (V/V ═ 1:1) type electrolyte and a Li sheet are used as counter electrodes to assemble the button cell.
FIG. 6 (a) is a graph showing the cycle characteristics of a battery having a current density of 100 mA/g.
As shown in FIG. 6 (a), the first-turn capacity was 1350mAh/g, and the discharge capacity after 100 turns was 450 mAh/g.
Fig. 6 (b) is a rate performance diagram of the battery.
As shown in fig. 6 (b), after different current density charge-discharge cycles, the material has good rate performance and can ensure that the material structure is not damaged in the process of multiple rapid charge-discharge.
Effects and effects of the embodiments
According to the method for preparing the lithium ion battery material by adopting the super-assembly and the dealloying, the controllable preparation of the high-activity composite metal oxide/graphene nano composite material is realized by freely corroding in a strong electrolyte solution and utilizing the electrostatic adsorption between the oxide and the graphite oxide by combining the super-assembly method. The material prepared by the method has controllable components and structure, zero loss of target material and suitability for large-scale production. The composite of the oxide and the graphene can integrate the advantages of two components and improve the electrochemical performance of a single material.
The lithium ion battery material obtained according to the embodiment is any one of a micron-sized dendritic material composed of nanosheets as basic units, an irregular composite material composed of nanosheets and graphene lamellar structures, or a nanoparticle close-packed material composed of nanorods as basic units, and the lithium ion battery material is a micron material composed of nanomaterials as basic units, namely a micro-nano structure. The nano material has high surface activation energy and large specific surface area, and can improve the lithium storage capacity when used as a lithium ion battery material; the micron material has the characteristics of high tap density, good stability and easy preparation. The lithium ion battery material obtained by the invention is used as a lithium ion battery cathode material, takes the nano-sheet or nano-rod as a basic unit, has high specific surface area and abundant active sites, and can improve the diffusion rate of lithium ions; the integral micron-sized dendritic structure can prevent the nano sheets from agglomerating, effectively relieve the volume expansion caused by the lithium ions in the de-intercalation process and improve the circulation stability of the material.
The above description is only a preferred embodiment of the present invention, and it should be noted that several improvements and modifications can be made without departing from the technical principle of the present invention, and these modifications and modifications should also be regarded as the protection scope of the present invention.

Claims (9)

1. A method for preparing a lithium ion battery material by adopting super-assembly and dealloying is characterized by comprising the following steps:
step S1, placing the ternary alloy sheet in a hydrogen peroxide solution, adding a strong alkali solution into the hydrogen peroxide solution, and performing a dealloying reaction at a preset temperature to obtain a dealloyed material;
step S2, placing the dealloying material in ethanol, performing ultrasonic treatment for a period of time, adding aminopropyl trimethoxysilane, and performing ultrasonic treatment for a period of time to obtain a precursor;
step S3, preparing graphene oxide powder into graphene oxide dispersion liquid, and mixing the precursor and the graphene oxide dispersion liquid according to a certain mass ratio to obtain a mixed solution;
step S4, adding ammonia water into the mixed solution, stirring for reaction, adding citric acid, and continuously stirring at a certain temperature to obtain a material intermediate;
step S5, heating the material intermediate to a certain temperature in a preset atmosphere, preserving the heat for a certain time, cooling to room temperature to obtain the lithium ion battery material,
wherein in step S1, the ternary alloy sheet comprises the components of Al, Co and Ni,
in step S1, the predetermined temperature is 25 ℃ to 60 ℃,
the dealloying reaction time is 2-12 h,
in the step S3, the mass ratio of the precursor to the graphene oxide is 20-30: 1,
in step S5, the certain temperature is 300-600 ℃,
the certain time is 5-10 h,
the lithium ion battery material is any one of micron-sized dendritic material formed by using nano sheets as basic units, irregular composite material formed by a nano sheet and a graphene sheet layer structure or nano particle close-packed material formed by using nano rods as basic units,
the diameter of the nano-sheet is 100nm,
the length of the micron-sized branches is 3-4 mu m,
the diameter of the nano rod is 5nm, the length is 30nm,
the nanoparticle size was 300 nm.
2. The method of preparing lithium ion battery material using super assembly and dealloying of claim 1, wherein:
in step S1, the atomic percent of Al in the ternary alloy sheet is 70-90%;
the percentage of total atoms of Co/Ni alloy in the ternary alloy sheet is 10-30%;
the atomic percent of the Co in the Co/Ni alloy is more than 0 and less than 100 percent.
3. The method of preparing lithium ion battery material using super assembly and dealloying of claim 2, wherein:
in step S1, the atomic percent of Al in the ternary alloy sheet is 80%;
the total atomic percent of the Co/Ni alloy in the ternary alloy sheet is 20%;
the Co/Ni alloy contains 25, 50, or 75 atomic% of Co.
4. The method of preparing lithium ion battery material using super assembly and dealloying of claim 1, wherein:
wherein, in step S4, a purification step is further included;
the purification steps are specifically as follows: taking the material intermediate, washing the material intermediate with water until the pH value of the supernatant is 7, and then performing vacuum drying at 60 ℃ for 12h to obtain the purified material intermediate, wherein the purified material intermediate is used in step S5 at a preset temperature in an atmosphere.
5. The method of preparing lithium ion battery material using super assembly and dealloying of claim 1, wherein:
in step S1, the strong alkali solution is a sodium hydroxide solution or a potassium hydroxide solution;
the amount of the substance of the strong alkali solution is 100 times of the dealloying equivalent;
the concentration of the hydrogen peroxide is 3.0-9.8M;
the concentration of the strong alkali solution is 0.1-6M;
in the step S2, the aminopropyl trimethoxysilane is 0.5-2 mL;
step S4, the ammonia water is 50-100 muL;
the citric acid is 30-100 mg.
6. The method of preparing lithium ion battery material using super assembly and dealloying of claim 1, wherein:
in step S5, the predetermined atmosphere is any one of argon, nitrogen, or a mixed gas of hydrogen and argon.
7. The method of preparing lithium ion battery material using super assembly and dealloying of claim 6, wherein:
in step S5, the argon gas in the mixed gas is high-purity argon gas having a purity of not less than 99.9%.
8. The method of preparing lithium ion battery material using super assembly and dealloying of claim 7, wherein:
in step S5, the volume content of the hydrogen gas in the mixed gas is 5% to 10%.
9. A lithium ion battery material, which is prepared by the method for preparing the lithium ion battery material by adopting super-assembly and dealloying as described in any one of claims 1 to 8.
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