CN112002882B

CN112002882B - Indium selenide/nitrogen doped reduced graphene oxide composite material and preparation method and application thereof

Info

Publication number: CN112002882B
Application number: CN202010829785.9A
Authority: CN
Inventors: 程敏; 李建荣; 黄小荥
Original assignee: Fujian Institute of Research on the Structure of Matter of CAS
Current assignee: Fujian Institute of Research on the Structure of Matter of CAS
Priority date: 2020-08-18
Filing date: 2020-08-18
Publication date: 2022-02-18
Anticipated expiration: 2040-08-18
Also published as: CN112002882A

Abstract

The application discloses an indium selenide/nitrogen doped reduced graphene oxide composite material and a preparation method and application thereof, wherein the composite material comprises reduced graphene oxide, and indium selenide nanodots are loaded on the surface of the reduced graphene oxide; the composite material is doped with nitrogen elements. According to the method, the ionic liquid containing the seleno-indium acid radical nanoparticles is used as a precursor to serve as a morphology regulator, an interface assembly medium, a metal source, a carbon/nitrogen source and the like, and effective compounding of the indium selenide nanoparticles and heteroatom-doped reduced graphene oxide is induced. The nano indium selenide in the obtained indium selenide/nitrogen-doped reduced graphene oxide composite material uniformly grows on the reduced graphene oxide sheet layer, and the average particle size is 3-10 nm. The nano indium selenide and the reduced graphene oxide have high bonding strength, and the nano particles have the characteristics of uniform appearance, small size and the like. The composite material is used as a battery negative electrode material and shows good electrochemical lithium storage activity.

Description

Indium selenide/nitrogen doped reduced graphene oxide composite material and preparation method and application thereof

Technical Field

The application relates to an indium selenide/nitrogen doped reduced graphene oxide composite material and a preparation method and application thereof, belonging to the field of energy storage.

Background

Lithium Ion Batteries (LIBs) have the advantages of high energy density, high operating voltage, low self-discharge, long cycle life, environmental protection, and the like, and are one of the most promising energy storage devices at present. LIBs have been widely studied to meet the increasing demand for various energy applications, from traditional portable electronic devices to emerging fields, such as electric vehicles and grid storage. However, the commercial secondary lithium ion battery usually adopts graphite as the negative electrode material of the lithium ion battery, and its lower theoretical capacity (372 mA h/g) can not meet the demand of people, so it is important to develop the electrode material with high energy density and high rate capability: (Adv. Mater., 2018, 30, 1800561）。

The metal chalcogenide with high theoretical capacity has been widely used in the research of lithium ion negative electrode material in recent years: (Adv. Mater., 2010, 22, E170-E192). However, there are still some problems with metal chalcogenides as LIBs anode materials: poor conductivity, large volume change, low capacity retention rate, and the like. To overcome these problems, extensive research has been conducted. In recent decade, the research on the application of graphene in the aspect of lithium ion battery negative electrode materials is endless due to the advantages of light weight, large specific surface area, good conductivity and the like. The graphene not only can buffer volume expansion, but also has a larger specific surface area of Li⁺Provides a rich route and provides a large contact area for the electrolyte and the electrode. Heteroatom doping can adjust the energy band structure of graphene and generate more pairs of Li⁺The adsorption of the graphene has active defects and edge positions, the conductivity and the electron transmission rate of the graphene can be improved, and the doped heteroatom can be used as an electron donor, so that the heteroatom-doped graphene can show more excellent performances compared with pure graphene. Heteroatom doped graphene can provide a good conductive network to compensate for the poor conductivity of metal chalcogenides. The quantum dot structure grown on the graphene has higher electron transmission rate, higher electrolyte contact area and structural stability. The nanocrystallization of the cathode material can obviously improve the catalytic activity, shorten the ion transmission distance, increase the specific surface area and improve the cycle stability of the electrode material. Therefore, how to effectively compound the metal chalcogenide with the graphene while performing nanocrystallization by a simple, convenient, safe and pollution-free method is the key for solving the problem.

Disclosure of Invention

According to one aspect of the application, the indium selenide/nitrogen-doped reduced graphene oxide composite material is provided, nitrogen elements are doped in the composite material, indium selenide nano particles are loaded on the surface of the reduced graphene oxide, the electron transmission rate and the electrolyte contact area of the composite material are improved, and the composite material is used as a lithium ion battery cathode material and shows good electrochemical lithium storage activity.

The composite material comprises reduced graphene oxide, wherein indium selenide nano-particles are loaded on the surface of the reduced graphene oxide;

the composite material is doped with nitrogen elements.

Specifically, nitrogen is doped in the reduced graphene oxide.

Optionally, the weight percentage of the indium selenide nanoparticles in the composite material is 20 wt% to 80 wt%.

Specifically, the lower limit of the weight percentage content of the indium selenide nanoparticles can be independently selected from 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%; the upper limit of the weight percentage of the indium selenide nanoparticles may be independently selected from 45 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%.

Optionally, the size of the indium selenide nano-particles is 3 nm-10 nm.

Optionally, in the composite material, the weight percentage of the nitrogen element is 2.0wt% to 4.0 wt%.

Specifically, the lower limit of the weight percentage content of the nitrogen element can be independently selected from 2.0wt%, 2.2 wt%, 2.5 wt%, 2.7 wt%, 3.0 wt%; the upper limit of the weight percentage of the nitrogen element can be independently selected from 3.2 wt%, 3.5 wt%, 3.7 wt%, 3.9 wt% and 4.0 wt%.

The overall appearance of the indium selenide/nitrogen-doped reduced graphene oxide composite material is that indium selenide nano-dot particles with the particle size of 3-10 nm are attached to the surface structure of reduced graphene oxide.

In the application, a nitrogen source in the indium selenide/nitrogen-doped reduced graphene oxide composite material is a seleno-indium-containing acid radical nanoparticle ionic liquid.

According to another aspect of the application, a preparation method of the indium selenide/nitrogen doped reduced graphene oxide composite material is provided.

The method comprises at least the following steps:

s001, obtaining a dispersion liquid I containing a precursor I, wherein the precursor I is an ionic liquid containing seleno-indium acid radical nano-particles;

s002, obtaining a dispersion liquid II containing graphene oxide;

s003, mixing the dispersion liquid I and the dispersion liquid II to obtain an initial product;

and S004, heating the primary product to obtain the indium selenide/nitrogen doped reduced graphene oxide composite material.

Alternatively, in step S001, precursor i is prepared by at least the following method:

mixing indium powder, selenium powder and ionic liquid, and carrying out microwave heating reaction to obtain the ionic liquid containing seleno-indium acid radical nanoparticles.

Alternatively, in step S001, the dispersion i containing the precursor i is obtained by at least the following method:

and adding an organic solvent I into the ionic liquid containing the seleno-indium acid radical nano-particles, and uniformly dispersing to obtain a dispersion liquid I.

Optionally, the ratio of the amounts of the indium powder, the selenium powder and the ionic liquid is 1: 1.7-2.2: 4-5.5.

Preferably, the mass ratio of the indium powder, the selenium powder and the ionic liquid is 1: 1.7-2: 4-5.5. Further preferably, the mass ratio of the indium powder, the selenium powder and the ionic liquid is 1: 1.7-2: 4.2-4.7.

Specifically, in the ratio of the amounts of the indium powder, the selenium powder and the ionic liquid, the lower limit of the amount of the selenium powder can be independently selected from 1.70, 1.75, 1.80, 1.85 and 1.90; the upper limit of the dosage of the selenium powder can be independently selected from 1.95, 2.00, 2.05, 2.10 and 2.2.

Specifically, in the ratio of the amounts of indium powder, selenium powder and ionic liquid, the lower limit of the amount of ionic liquid used may be independently selected from 4.0, 4.3, 4.5, 4.7 and 5.0; the upper limit of the dosage of the ionic liquid can be independently selected from 5.1, 5.2, 5.3, 5.4 and 5.5.

Optionally, the ionic liquid is an imidazole ionic liquid;

preferably, in the imidazole ionic liquid, the cation comprises at least one of imidazole ring and substituted imidazole ring; the anion is selected from the group consisting of halide, preferably, chloride.

Further preferably, the ionic liquid is at least one of 1-propyl-2, 3-dimethylimidazole chloride, 1-butyl-2, 3-dimethylimidazole chloride, 1-pentyl-2, 3-dimethylimidazole chloride, 1-hexyl-2, 3-dimethylimidazole chloride, 1-octyl-2, 3-dimethylimidazole chloride, 1-propyl-2, 3-dimethylimidazole bromide, and 1-pentyl-2, 3-dimethylimidazole bromide.

Optionally, in the dispersion liquid I, the concentration of the precursor I is 0.45-0.65 g/mL;

preferably, the organic solvent I is at least one of N-methyl pyrrolidone, acetonitrile and dimethylformamide. Further preferably, the organic solvent I is N-methylpyrrolidone.

Specifically, the lower limit of the concentration of the precursor I can be independently selected from 0.45 g/mL, 0.47 g/mL, 0.50 g/mL, 0.53 g/mL and 0.55 g/mL; the upper concentration limit of the precursor I can be independently selected from 0.57 g/mL, 0.59 g/mL, 0.60 g/mL, 0.63 g/mL, 0.65 g/mL.

Optionally, the microwave heating reaction conditions are as follows: the temperature is increased to 160-210 ℃ and the heating is continued for 30-60 minutes.

Preferably, the microwave heating reaction conditions are: the temperature is increased to 180-200 ℃ and the heating is continued for 30-45 minutes. Further preferably, the temperature is raised to 180-200 ℃ for 30-45 minutes after preheating to 120-150 ℃ for 5-10 minutes.

Specifically, the lower limit of the temperature rise temperature can be independently selected from 160 ℃, 165 ℃, 170 ℃, 175 ℃ and 180 ℃; the upper limit of the temperature rise temperature may be independently selected from 185 ℃, 190 ℃, 195 ℃, 200 ℃ and 210 ℃.

Specifically, the lower limit of the heating time may be independently selected from 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes; the upper limit of the heating time may be independently selected from 52 minutes, 54 minutes, 55 minutes, 57 minutes, 60 minutes.

Optionally, in step S002, the reduced graphene oxide source is a graphene oxide dispersion liquid, and the solvent in the dispersion liquid ii is at least one of N-methylpyrrolidone NMP, ethanol, and distilled water; preferably, the solvent is NMP.

Preferably, in the dispersion liquid II, the concentration of the graphene oxide is 3-4 mg/mL;

preferably, the volume ratio of the dispersion liquid I to the dispersion liquid II is 1: 4.5-20.

Specifically, the lower limit of the concentration of the precursor I can be independently selected from 3.0mg/mL, 3.1mg/mL, 3.2mg/mL, 3.3mg/mL and 3.5 mg/mL; the upper limit of the concentration of precursor I can be independently selected from 3.6mg/mL, 3.7mg/mL, 3.8mg/mL, 3.9mg/mL, 4.0 mg/mL.

Specifically, in the volume ratio of the dispersion liquid I to the dispersion liquid II, the lower limit of the using amount of the dispersion liquid II can be independently selected from 4.5, 4.55, 5, 7 and 10; the upper limit of the amount of the dispersion II can be independently selected from 12, 15, 17, 19 and 20.

In the specific implementation process of the present application, step S003 may be: slowly adding the ionic liquid dispersion liquid containing the seleno-indium acid radical nanoparticles into the graphene oxide dispersion liquid, fully stirring for a period of time I, then adding ethanol and distilled water to dilute and stir for a period of time II, centrifuging the mixed liquid, and taking the solid at the bottom for vacuum drying to obtain a primary product.

Stirring I and II for at least 10 min. Preferably, the stirring time I is 15-40 min, and the stirring time II is 15-30 min.

The amount of ethanol and distilled water can be selected by those skilled in the art according to the actual need, in order to completely precipitate the primary product.

The separation method and the drying method in step S003 can be selected by those skilled in the art according to the actual needs. Preferably, the method for separating the precipitated solid in step S003 is centrifugation.

Optionally, step S003 further includes drying the primary product;

the drying temperature is 60-80 ℃, and the drying time is 8-12 hours.

Specifically, the lower limit of the temperature rise temperature can be independently selected from 60 ℃, 62 ℃, 64 ℃, 66 ℃ and 68 ℃; the upper limit of the temperature rise temperature may be independently selected from 70 ℃, 72 ℃, 75 ℃, 77 ℃, 80 ℃.

Specifically, the lower limit of the drying time may be independently selected from 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours; the upper limit of the drying time may be independently selected from 10.5 hours, 11 hours, 11.5 hours, 11.7 hours, 12 hours.

Alternatively, in step S004, the heat treatment is specifically: introducing protective gas at the temperature of 250-400 ℃, and carrying out heat treatment for 1-4 hours;

the protective gas comprises inactive gas;

preferably, the heating rate is 1-5 ℃/min;

preferably, the protective gas is a mixed gas of hydrogen and nitrogen in a volume ratio of 1: 9. The mixed protective atmosphere can prevent the generation of indium-based oxide.

Specifically, the lower limit of the heat treatment temperature can be independently selected from 250 ℃, 260 ℃, 270 ℃, 280 ℃ and 290 ℃; the upper limit of the heat treatment temperature may be independently selected from 300 deg.C, 320 deg.C, 350 deg.C, 370 deg.C, 400 deg.C.

Specifically, the lower limit of the heat treatment time may be independently selected from 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours; the upper limit of the heat treatment time may be independently selected from 3.2 hours, 3.4 hours, 3.5 hours, 3.7 hours, 4 hours.

As a specific embodiment of the present application, the method comprises the steps of:

a) mixing indium powder, selenium powder and ionic liquid in a quartz reaction tube according to the mass ratio of substances of 1: 1.7-2.2: 4-5.5, sealing, preheating the mixture to 120-150 ℃ in a Biotage microwave instrument, maintaining the temperature for 5-10 min, then raising the temperature to 180-200 ℃ and continuously heating for 30-45 min, then naturally cooling to room temperature to obtain ionic liquid containing seleno-indium acid radical nano-particles, and under the condition of water bath heating, preferably, adopting boiling water bath heating to disperse the ionic liquid in 15 mL of NMP organic solvent to obtain precursor dispersion liquid containing the seleno-indium acid radical nano-particles with better dispersity, wherein the concentration of the dispersion liquid is 0.45-0.65 g/mL;

the ionic liquid is halogen-containing ionic liquid, cations of the ionic liquid comprise imidazole ionic liquid and derivatives thereof, and anions of the ionic liquid are halide ions;

b) graphene oxide was prepared according to the modified Hummers method. Dispersing 200 mg of graphene oxide in 50-60 mL of NMP to form a dispersion liquid containing graphene oxide sheets;

c) slowly dropwise adding 3-11 mL of the precursor dispersion liquid containing the seleno-indium acid radical nanoparticles prepared in the step a) into the dispersion liquid containing the graphene oxide sheet layer obtained in the step b) while stirring vigorously, uniformly mixing, adding anhydrous ethanol and deionized water according to needs to separate out a compound, and centrifuging and drying in vacuum to obtain a compound product;

d) carrying out heat treatment on the product obtained in the step c), wherein the purpose of the process is to pyrolyze the ionic liquid coated on the surface of the seleno-indium acid radical-containing nano particles, and simultaneously reducing the graphene oxide to form the indium selenide/nitrogen doped reduced graphene oxide composite material.

According to another aspect of the application, a cathode material is provided, and the cathode material comprises at least one of the indium selenide/nitrogen-doped reduced graphene oxide composite material and the indium selenide/nitrogen-doped reduced graphene oxide composite material prepared by any method.

According to yet another aspect of the present application, there is provided a lithium ion battery comprising the above-described anode material.

Ionic Liquids (ILs) are a room temperature molten salt. ILs can form extended hydrogen bonding systems in liquid state, have excellent ability to assemble and stabilize various nanostructures, and can form special interface effects with carbon materials (carbon nanotubes or graphene) by using C-H · · s electrostatic interactions. ILs are able to optimize the morphology, nanostructure, chemical composition and function of electrode materials in a more gentle way than other synthetic media.

The ionic liquid containing seleno-indium acid radical nano-particles is used as a precursor, multiple functions of using the ionic liquid as a metal source and a carbon/nitrogen source in a synthesis process, inducing the ionic liquid to form nano-particles in an indium selenide nucleation process and the like are exerted, and finally the high-performance lithium ion battery cathode material is obtained.

The ionic liquid containing seleno-indium acid radical nano-particles is prepared massively by the reaction of indium metal and selenium simple substance by adopting a microwave ionic thermal method. The ionic liquid containing the seleno-indium acid radical nano-particles plays the roles of a metal source, a carbon/nitrogen source and a dual stabilizer in the process of synthesizing the composite material: the ionic liquid and oxygen-containing groups on the surface of the graphene oxide have strong electrostatic interaction, so that indium selenide nano-particles and reduced graphene oxide can be better compounded, and the indium selenide nano-particles are formed in the nucleation process of indium selenide. The nano indium selenide in the obtained indium selenide/nitrogen-doped reduced graphene oxide composite material uniformly grows on the reduced graphene oxide sheet layer, and the average particle size is 3-10 nm. The nano indium selenide and the reduced graphene oxide have high bonding strength, and the nano particles have the characteristics of uniform appearance, small size and the like. The composite material is used as a battery negative electrode material and shows good electrochemical lithium storage activity.

The beneficial effects that this application can produce include:

(1) according to the indium selenide/nitrogen-doped reduced graphene oxide composite material, the size of a nanoparticle formed by indium selenide on a reduced graphene oxide conducting network is 3-10 nm, the indium selenide nanoparticle is uniform in shape, small in size and uniform in particle size, and a quantum dot structure grown on the reduced graphene oxide has a higher electron transmission rate.

(2) According to the preparation method of the indium selenide/nitrogen-doped reduced graphene oxide composite material, the ionic liquid containing seleno-indium acid radical nanoparticles is used as a precursor to serve as a morphology regulator, an interface assembly medium, a metal source, a carbon/nitrogen source and other multiple roles, and effective compounding of the indium selenide nanoparticles and the heteroatom-doped reduced graphene oxide is induced.

(3) The preparation method of the indium selenide/nitrogen-doped reduced graphene oxide composite material is simple in process, high in safety and suitable for industrial large-scale production.

(4) The indium selenide/nitrogen-doped reduced graphene oxide composite material provided by the application is used as a lithium ion battery cathode material for battery assembly, and 100 mAg is carried out at 30 DEG C^-1After 180 charge-discharge cycles under the current density, the reversible charge-discharge specific capacity can reach 1077.4 mAhg^-1(ii) a At 5000 mAg^-1The specific capacity can still maintain 673.7 mAhg after 1000 cycles under the high current density^-1The lithium ion battery cathode material has excellent electrochemical performance and is expected to become a novel lithium ion battery cathode material.

Drawings

FIG. 1 shows an embodiment of the present applicationIn prepared In example 1₂Se₃-11@ NG experimental spectrum, and powder diffractogram of standard spectrum;

FIG. 2 shows In prepared In example 1 of the present application₂Se₃-XPS energy spectrum of 11@ NG;

FIG. 3 shows In prepared In example 1 of the present application₂Se₃-11@ NG, wherein FIG. 3 (a) is a scanning electron micrograph and FIGS. 3 (b) and 3 (c) are transmission electron micrographs at 100nm and 20nm, respectively;

FIG. 4 shows In prepared In example 1 of the present application₂Se₃-11@ NG cyclic voltammogram at a sweep rate of 0.1 mV/s;

FIG. 5 shows In prepared In example 1 of the present application₂Se₃-11@ NG capacity cycling plot at current density 100 mA/g;

FIG. 6 shows In prepared In example 1 of the present application₂Se₃-11@ NG capacity cycling plot at current density 5000 mA/g;

FIG. 7 shows In prepared In example 1 of the present application₂Se₃-11@ NG lithium insertion/extraction rate cycling test plot.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

Unless otherwise specified, the raw materials in the examples of the present application were commercially available, wherein indium powder was obtained from metal chemical industries, ltd, source of hunting, guangzhou, selenium powder was obtained from chemical reagent factories, rarefied, and 1-butyl-2, 3-dimethylimidazolium chloride was obtained from orlistat, ltd.

In the embodiment of the present application, an improved Hummer method is adopted to prepare a graphene oxide solution, which is described in reference (ACS Nano, 2010,4, 4806–4814）。

in the examples of the present application, X-ray powder diffraction phase analysis (XRD) was carried out at 30 kV, 15mA on a Miniflex type II X-ray diffractometer from Rigaku corporation, Cu target,Kαradiation source (λ=1.54178 Å）。

X-ray photoelectron spectroscopy (XPS) analysis was performed on ESCALAB 250Xi instrument from zemer hewler.

Fourier transform Infrared Spectroscopy (FTIR) analysis was performed on a Vertex 70 instrument from Bruker.

Transmission Electron Microscopy (TEM) analysis was performed on a JEM-2100F high resolution transmission electron microscope, Japan Electron Ltd.

Scanning Electron Micrograph (SEM) analysis was performed on a JSM-7500F Cold field emission scanning Electron microscope, Japan Electron Ltd.

The weight percentage content of the nano indium selenide in the indium selenide/nitrogen doped reduced graphene oxide nano composite material is obtained by testing/calculating on a Vario EL III instrument of Germany element analysis systems company.

In the method, anions and cations of the ionic liquid are used as stabilizers to act synergistically to stabilize small-sized indium selenide-based nanoparticles, small-sized nanoparticles are formed in an indium selenide nucleation process in an inducing mode, and the size of indium selenide particles on the surface of reduced graphene oxide in the material is 3-10 nm; and cations of the graphene oxide are also used as a carbon source to be converted into an amorphous carbon layer to ensure that nano particles are not agglomerated in the heat treatment process, and are used as a nitrogen source to realize nitrogen doping of reduced graphene oxide (rGO) and improve the conductivity of the substrate.

Example 1

Preparation of samples

a) Indium powder, selenium powder and ionic liquid (1-butyl-2, 3-dimethyl imidazole chloride) are mixed according to the mass ratio of 1: 1.7:4.5, added into a 20mL Biotage quartz microwave reaction tube and sealed, heated to 150 ℃ under the microwave condition for 5 minutes, then heated at 180 ℃ for 45 minutes at constant temperature, naturally cooled to room temperature, and added with 15 mL of N-methyl pyrrolidone (NMP) under the condition of 100 ℃ water bath heating for dispersion to obtain precursor dispersion liquid containing seleno-indium acid radical nanoparticles, wherein the concentration of the precursor in the dispersion liquid is 0.51 g/mL.

b) Graphene oxide was prepared according to the modified Hummers method. Dispersing 200 mg of graphene oxide in 50 mLNMP to form a dispersion liquid containing graphene oxide sheets;

c) slowly dripping 11 mL of the precursor dispersion liquid obtained in the step a) into the dispersion liquid containing the graphene oxide sheet layer obtained in the step b) under the condition of vigorous stirring, adding 50mL of absolute ethyl alcohol and 20mL of distilled water after uniform dispersion, continuously stirring for 30 min, centrifuging to obtain a solid, washing for three times by using distilled water and ethanol respectively, and performing vacuum drying for 10 hours at the temperature of 60 ℃ to obtain a primary product;

d) heat-treating the primary product obtained in step c) in a vacuum tube furnace: heating to 300 ℃ at a heating rate of 2 ℃/min under a mixed atmosphere of hydrogen and nitrogen in a volume ratio of 1:9, and carrying out heat treatment for 2 hours to obtain the nano indium selenide/nitrogen doped reduced graphene oxide composite material.

The differences in the preparation parameters for the other samples from sample # 1 according to the above procedure are shown in table 1:

TABLE 1

Sample (I)

Ionic liquids

The ratio of the amounts of indium powder, selenium powder and ionic liquid

Amount of precursor (mL)

Heat treatment temperature rise Rate (DEG C/min)

Temperature and time of microwave heating

Conditions of heat treatment

1#

Chlorinated 1-butyl-2, 3-dimethylimidazole

1：1.7：4.5

11

2

200℃ 45min

300℃ 2h

2#

Brominated 1-propyl-2, 3-dimethylimidazoles

1：1.7：4.0

5

1

180℃ 55min

320℃ 2h

3#

Chlorinated 1-hexyl-2, 3-dimethylimidazoles

1：2：4.5

3

190℃ 55min

350℃ 1h

4#

Chlorinated 1-octyl-2, 3-dimethylimidazole

1：2：4.0

9

4

190℃ 45min

300℃ 3h

5#

Brominated 1-pentyl-2, 3-dimethylimidazole

1：2.2：5.5

7

5

210℃ 60min

300℃ 1h

EXAMPLE 2 characterization of the samples

Sample 1 obtained in example 1 was subjected to X-ray powder diffraction^#Sample 5^#Characterization was performed with sample 1^#Typically, the XRD spectrum is shown in FIG. 1, and sample 2^#Sample 5^#The XRD pattern of the sample is similar to that of FIG. 1, namely, the positions of diffraction peaks are basically the same, and the peak intensities of different samples are slightly different. As can be seen from FIG. 1, the diffraction peaks and In the experimental spectrum of the obtained product₂Se₃The phase standard spectrum (PDF # 40-1407) corresponds well, and a significant reduced graphene oxide peak is formed at a diffraction angle of about 27 degrees. From this, it was confirmed that the obtained product was In₂Se₃And reduced graphene oxide.

The sample 1 is obtained by adopting a Vario EL III instrument for testing/calculation^#The weight percentage content of the medium nano indium selenide is 64.41 wt%.

Sample 1 obtained in example 1 was subjected to X-ray photoelectron spectroscopy (XPS)^#Sample 5^#Characterization was performed with sample 1^#Typical XPS spectrum is shown in FIG. 2, sample 2^#Sample 5^#The XPS spectrum of (A) is similar to that of FIG. 2. As can be seen from FIG. 2, the final product is successfully doped with nitrogen, the electron binding energy of C1 s is 284.8 eV, which exactly coincides with the position in the XPS spectrum, indicating that the graphene oxide in the final product has been reduced to reduced graphene oxide. The content of nitrogen element was 2.79 wt%.

The appearance of samples 1# to 5# in example 1 is characterized by using a scanning electron microscope and a transmission electron microscope, the sample 1# is taken as a typical representative, the scanning electron microscope image of the sample is shown in fig. 3a, and it can be seen from the image that indium selenide in the composite material is attached to the surface of reduced graphene oxide in a nano-dot structure. Transmission electron microscope of sample No. 1As shown In FIGS. 3b and 3c, In is seen₂Se₃Quantum dots supported on reduced graphene oxide sheets, and In₂Se₃The particle size of (A) is 3-10 nm. For final product sample 2^#Sample 5^#Characterization was performed, the results are compared with sample 1^#Similarly.

Example 3 cyclic voltammetry of lithium ions

With sample 1^#For typical representation, cyclic voltammograms were tested as follows:

preparing the heat-treated composite material, conductive carbon black serving as a conductive agent and polyvinylidene fluoride (PVDF) serving as a binder into slurry according to the weight ratio of 8:1:1, uniformly coating the slurry on the surface of a copper foil of a negative current collector, drying the slurry at 120 ℃ in vacuum, and then performing tabletting, slicing, weighing and other operations to obtain the negative plate. Uniformly mixing Ethylene Carbonate (EC), diethyl carbonate (DMC) and diethyl carbonate (DEC) according to the volume ratio of EC to DMC to DEC =1:1:1, and adding LiPF₆Obtaining LiPF₆And (3) adding 5% of vinyl fluoride carbonate (the volume fraction of the vinyl fluoride carbonate in the electrolyte is 5%) into the solution with the concentration of 1mol/L to obtain the electrolyte. And (3) assembling the half cell in a glove box by taking the Celgard 2325 composite membrane as a diaphragm and taking the metal lithium as a positive plate.

In which cyclic voltammograms were tested on the electrochemical workstation of chenhua CHI 650E. The scan voltage range is 0.05-3V, the scan rate is 0.1mV/s, and the results are shown in FIG. 4. It can be seen from fig. 4 that in the 2 nd and 3 rd scanning processes, the positions and intensities of the cathode peak and the anode peak are basically stable, and the areas of the two scanning circles are basically consistent, which indicates that the obtained product has good reversible electrochemical reaction activity.

Example 4 electrochemical Performance characterization

For sample 1^#The lithium intercalation/deintercalation cycle life of (a) was tested as follows:

the button cells assembled in example 3 were tested on the wuhan blue and LAND 2001A systems. The circulating voltage is 0.05-3V, and the obtained battery is subjected to constant-current charge-discharge circulation for 3 circles under the condition of low current (10 mA)And (4) activating. The test results are shown in fig. 5 and 6, and it can be seen that the lithium ion battery assembled by using the composite material as the negative electrode material has a current density of 100 mAg at a temperature of 30 DEG C^-1Under the condition of (1), after circulating for 3 circles, the coulombic efficiency reaches over 99 percent and is kept all the time, and the specific discharge capacity after circulating for 180 circles is 1077.4mAh g⁻¹(ii) a At 5000 mAg^-1The specific discharge capacity after 1000 cycles of circulation under the current density is 673.7mAh g⁻¹And the coulomb efficiency in the circulation process is also kept above 99%.

The button cells assembled in example 3 were tested on the wuhan blue and LAND 2001A systems. The cycle voltage interval is 0.05-3V, and the battery is activated by constant current charge-discharge cycle for 3 circles under the condition of low current (20 mA). The test results are shown in FIG. 7 at 100, 200, 500, 1000, 2000 and 5000mA g^-1The circulating capacity under the current density condition can reach 950, 870, 790, 700, 610 and 490mAh g respectively⁻¹When the current density returns to 100mA g again^-1The specific discharge capacity can still reach 1100mAh g⁻¹. Therefore, the battery has high capacity and good stability under low current density and high current density, and has good rate performance, which indicates that the composite material has good electrochemical performance as a lithium ion negative electrode material.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims

1. The lithium ion battery cathode material is characterized by comprising an indium selenide/nitrogen doped reduced graphene oxide composite material; the composite material comprises reduced graphene oxide, wherein indium selenide nano-particles are loaded on the surface of the reduced graphene oxide; the indium selenideHas a chemical formula of In₂Se₃；

The composite material is doped with nitrogen;

the preparation method of the indium selenide/nitrogen doped reduced graphene oxide composite material comprises the following steps:

s002, obtaining a dispersion liquid II containing graphene oxide;

2. The lithium ion battery anode material of claim 1, wherein the weight percentage of the indium selenide nanoparticles in the composite material is 20 wt% to 80 wt%.

3. The lithium ion battery anode material of claim 1, wherein the size of the indium selenide nanoparticles is 3 nm-10 nm.

4. The lithium ion battery negative electrode material of claim 3, wherein the weight percentage of the nitrogen element in the composite material is 2.0wt% to 4.0 wt%.

5. The lithium ion battery anode material according to claim 1, wherein in step S001, the precursor i is prepared by the following method:

6. The negative electrode material for a lithium ion battery according to claim 1, wherein in step S001, the dispersion i containing the precursor i is obtained by:

and adding an organic solvent I into the ionic liquid containing the seleno-indium acid radical nanoparticles, and uniformly dispersing to obtain the dispersion liquid I.

7. The negative electrode material for the lithium ion battery as claimed in claim 5, wherein the mass ratio of the indium powder, the selenium powder and the ionic liquid is 1: 1.7-2.2: 4-5.5.

8. The lithium ion battery negative electrode material of claim 1, wherein the ionic liquid is an imidazole-based ionic liquid.

9. The negative electrode material for the lithium ion battery according to claim 8, wherein in the imidazole-based ionic liquid, the cation comprises at least one of an imidazole ring and an imidazole ring containing a substituent group; the anion is selected from halide ions.

10. The lithium ion battery negative electrode material of claim 7, wherein the concentration of the precursor I in the dispersion liquid I is 0.45-0.65 g/mL.

11. The lithium ion battery negative electrode material of claim 6, wherein the organic solvent I is at least one of N-methylpyrrolidone, acetonitrile and dimethylformamide.

12. The lithium ion battery negative electrode material of claim 5, wherein the microwave heating reaction conditions are as follows: the temperature is increased to 160-210 ℃ and the heating is continued for 30-60 min.

13. The negative electrode material for a lithium ion battery according to claim 1, wherein in step S002, the solvent in the dispersion liquid ii is at least one of N-methylpyrrolidone, ethanol, and distilled water.

14. The lithium ion battery negative electrode material of claim 13, wherein the concentration of graphene oxide in the dispersion liquid II is 3-4 mg/mL.

15. The lithium ion battery negative electrode material as claimed in claim 13, wherein the volume ratio of the dispersion liquid I to the dispersion liquid II is 1: 4.5-20.

16. The negative electrode material for lithium ion batteries according to claim 13, wherein the step S003 further comprises drying the primary product;

the drying temperature is 60-80 ℃, and the drying time is 8-12 hours.

17. The lithium ion battery anode material according to claim 13, wherein in step S004, the heat treatment is specifically: introducing protective gas at the temperature of 250-400 ℃, and carrying out heat treatment for 1-4 hours;

the protective gas comprises inactive gas.

18. The lithium ion battery negative electrode material of claim 17, wherein the heating rate is 1-5 ℃/min.

19. The lithium ion battery negative electrode material of claim 18, wherein the shielding gas is a mixed gas with a volume ratio of hydrogen to nitrogen of 1: 9.