CN110828788B

CN110828788B - Porous NiFe2O4Graphene composite material and preparation method and application thereof

Info

Publication number: CN110828788B
Application number: CN201910954059.7A
Authority: CN
Inventors: 赵毅; 吴初新; 官轮辉
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: 2019-10-09
Filing date: 2019-10-09
Publication date: 2021-08-10
Anticipated expiration: 2039-10-09
Also published as: CN110828788A

Abstract

The application discloses a porous NiFe₂O₄The graphene composite material is characterized by comprising a graphene layer and porous NiFe₂O₄A layer; the porous NiFe₂O₄The layers coat both surfaces of the graphene layer. The application also discloses a preparation method and application of the composite material. The nanocomposite has excellent electrical properties.

Description

Porous NiFe2O4Graphene composite material and preparation method and application thereof

Technical Field

The invention belongs to the field of nano material preparation, and particularly relates to porous NiFe₂O₄Graphene composite material and preparation method and application thereof.

Background

Lithium Ion Batteries (LIBs) have enjoyed great success in the past few years in portable electronic products and electric vehicles. Recently, Sodium Ion Batteries (SIBs) have received increasing attention as an alternative technology to LIBs due to their abundant cost-effective sodium resources for their application in large-scale energy storage. In order to meet the increasing demand from the point of view of energy storage applications, it is crucial to explore new electrode materials with good safety, long-term cycling and high energy/power density of LIBs and SIBs. In the field of anode materials, commercial graphite for LIB has 372mA h g^-1Low theoretical capacity of (a). Further, Na when inserted into the raw graphite⁺Large ionic radii of (a) lead to poor reversibility. Iron-based Metal Oxides (MOs), including Fe, in the pursuit of good quality anode materials₂O₃，Fe₃O₄，MFe₂O₄(M ═ Ni, Co, Mn, Zn, Mg, etc.), and has been widely studied because of its high capacity, good environment, and low cost. Wherein, NiFe₂O₄Has a theoretical capacity of 915mA h g^-1. However, these anodes are in the presence of continuous Li⁺Or Na⁺Insert intoThe stripping process results in poor cell performance due to inherent low conductivity and large volume changes. For example, pure NiFe₂O₄The sample exhibited a rapid capacity fade as LIB anode.

Disclosure of Invention

According to one aspect of the present invention, there is provided a porous NiFe₂O₄Graphene composite materials.

The porous NiFe₂O₄The graphene composite material is characterized by comprising a graphene layer and porous NiFe₂O₄A layer; the porous NiFe₂O₄The layers coat both surfaces of the graphene layer.

The NiFe₂O₄Is nanoparticle with particle size of 3-5 nm.

Optionally, the porous NiFe₂O₄NiFe in the layer₂O₄Has a porous structure and the pore size distribution is 1-10 nm.

Optionally, the porous NiFe₂O₄Layer opposite to the porous NiFe₂O₄The mass content of the graphene composite material is 80-92 wt%.

Optionally, the porous NiFe₂O₄Layer opposite to the porous NiFe₂O₄The mass content of the graphene composite material is 85-90 wt%, and more preferably 87 wt%.

Optionally, the porous NiFe₂O₄Layer opposite to the porous NiFe₂O₄The upper limit of the mass content of the graphene composite material is selected from 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 90wt%, 91 wt%, or 92 wt%; the lower limit is selected from 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 90wt% or 91 wt%.

As a specific embodiment, a porous NiFe₂O₄The graphene composite material has the following structural general formula: g @ p-NiFe₂O₄Wherein G represents a graphene, p-NiFe₂O₄NiFe representing porous structure₂O₄The compound comprises graphene as the innermost layer and NiFe as the outer layer₂O₄Which is coated on the surface of the graphene layer.

The NiFe₂O₄As porous compounds, with p-NiFe₂O₄Indicating that the pore size is 1-10 nm.

The NiFe₂O₄The content of the binder is 80 to 92wt%, and more preferably 87 wt% based on the mass of the composite material.

According to another aspect of the present invention, there is provided a porous NiFe₂O₄A method for preparing a nanocomposite.

The porous NiFe₂O₄The preparation method of the nano composite material is characterized by comprising the following steps:

a) coating porous SiO on two surfaces of graphene layer₂Layer to obtain G @ p-SiO₂；

b) At G @ p-SiO₂Coated with NiFe on both surfaces₂O₄Layer to obtain G @ p-SiO₂@ NiFe₂O₄；

c)G@p-SiO₂@NiFe₂O₄Etching the-P to obtain G @ P-NiFe₂O₄I.e. the porous NiFe₂O₄A nanocomposite material.

Optionally, in step a), the G @ p-SiO₂The content of the graphene in the graphene is 3-12 wt%.

Optionally, in step a), the G @ p-SiO₂The upper limit of the content of the graphene in (b) is selected from 5 wt%, 6.3 wt%, 8 wt%, 10 wt% or 12 wt%; the lower limit is selected from 3 wt%, 5 wt%, 6.3 wt%, 8 wt% or 10 wt%.

Optionally, step a) comprises:

a21) dissolving a surfactant in a mixed solution containing water, ethanol and ammonia water to obtain a solution I;

a22) dispersing graphene oxide in the solution I, adding a silicon source, reacting, and reacting at 300-800 ℃ in an inert atmosphereFurther annealing for more than 1 hour to obtain G @ p-SiO₂。

Optionally, the surfactant in step a21) is a cationic surfactant; the cationic surfactant is at least one selected from alkyl quaternary ammonium salts.

Optionally, the cationic surfactant is selected from at least one of cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride, dodecyltrimethylammonium bromide, dodecyltrimethylammonium chloride.

Alternatively, the concentration of surfactant in said solution I in step a21) is between 0.5 and 1 wt%.

Optionally, the volume ratio of water, ethanol and ammonia water in the solution I in the step a21) is 1: (3-10): (0.01-0.04).

Optionally, the silicon source in step a22) is selected from ethyl orthosilicate.

Optionally, the inert atmosphere in step a22) is selected from at least one of nitrogen and noble gases.

Optionally, the upper limit of the temperature of the annealing in step a22) is selected from 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃ or 800 ℃; the lower limit is selected from 300 deg.C, 350 deg.C, 400 deg.C, 450 deg.C, 500 deg.C, 550 deg.C, 600 deg.C, 650 deg.C, 700 deg.C or 750 deg.C.

Optionally, the annealing time in the step a22) is 1-24 hours.

Optionally, the upper limit of the time of the annealing in step a22) is selected from 2 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, or 24 hours; the lower limit is selected from 1 hour, 2 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, or 20 hours. Optionally, step b) comprises:

g @ p-SiO₂Adding the mixture into a solution containing ferric salt and nickel salt, dispersing uniformly, removing the solvent, and annealing at 300-500 ℃ for more than 1 hour in an inert atmosphere to obtain the G @ p-SiO₂@ NiFe₂O₄。

Optionally, the molar ratio of iron in the iron salt to nickel in the nickel salt is 2: (0.1-1).

Optionally, the molar ratio of iron in the iron salt to nickel in the nickel salt is 2: 1.

optionally, the concentration of the iron salt in the solution containing the iron salt and the nickel salt is 0.002-0.02 mol/L.

Optionally, the concentration of the nickel salt in the solution containing the iron salt and the nickel salt is 0.001-0.01 mol/L.

Alternatively, G @ p-SiO₂The mass ratio of the iron ions to the nickel ions in the solution containing the iron salt and the nickel salt is respectively 1: (0.168-0.28), 1: (11.7-14.7).

Optionally, the upper limit of the temperature of the annealing in step b) is selected from 350 ℃, 400 ℃, 450 ℃ or 500 ℃; the lower limit is selected from 300 deg.C, 350 deg.C, 400 deg.C or 450 deg.C.

Optionally, the annealing time in the step b) is 1-12 hours.

Optionally, the upper limit of the time of the annealing in step b2) is selected from 2 hours, 5 hours, 8 hours, 10 hours or 12 hours; the lower limit is selected from 1 hour, 2 hours, 5 hours, 8 hours or 10 hours.

As an embodiment, the porous NiFe₂O₄The preparation method of the nano composite material is characterized by comprising the following steps:

1. coating porous silicon dioxide on the surface of the graphene sheet layer to obtain a graphene porous silicon dioxide compound, and coating G @ p-SiO₂Is represented by the formula G @ p-SiO₂The content of the graphene in the graphene is 3-12 wt%;

2. g @ p-SiO₂Adding the mixture into an ethanol solution containing ferric salt and nickel salt, uniformly dispersing, then completely evaporating the ethanol solvent, and annealing the obtained product in an inert atmosphere at the temperature of 300-500 ℃ for more than 1 hour to obtain the G @ SiO₂@NiFe₂O₄A complex;

the molar ratio of iron to nickel in the ferric salt and the nickel salt is 2 (0.1-1), wherein the ferric salt is one or more of ferric nitrate and ferric carboxylate; the nickel salt is one or more of nickel nitrate or nickel carboxylate;

3. by hot sodium hydroxide solution orHydrogen fluoride solution is used for dissolving SiO in the product of the step 2₂Etching and removing to obtain G @ p-NiFe₂O₄I.e. said porous NiFe₂O₄A nanocomposite material.

Optionally, said porous NiFe₂O₄The nano composite material has the following structural general formula: g @ p-NiFe₂O₄；

Wherein G represents graphene, p-NiFe₂O₄NiFe representing porous structure₂O₄The compound comprises graphene as the innermost layer and NiFe as the outer layer₂O₄Which is coated on the surface of the graphene layer.

As a specific embodiment, a porous NiFe₂O₄The preparation method of the graphene composite material comprises the following steps:

1. coating porous silicon dioxide (p-SiO) on the surface of the graphene sheet layer (G)₂) Obtaining the graphene porous silicon dioxide compound which is G @ p-SiO₂Is represented by the formula G @ p-SiO₂The content of the graphene in the graphene is 3-12 wt%;

2. g @ p-SiO₂Adding the mixture into an ethanol solution containing ferric salt and nickel salt, uniformly dispersing, then completely evaporating the ethanol solvent, and annealing the obtained product in an inert atmosphere at the temperature of 300-500 ℃ for more than 1 hour to obtain the G @ SiO₂@NiFe₂O₄The molar ratio of iron to nickel in the ferric salt and the nickel salt is 2:1, the ferric salt is one or more of ferric nitrate and ferric carboxylate, the nickel salt is one or more of nickel nitrate and nickel carboxylate respectively, and the ferric carboxylate and the nickel carboxylate refer to corresponding carboxylate which can be dissolved in an ethanol solvent;

3. SiO in the product of the step 2 is dissolved in hot sodium hydroxide solution or hydrogen fluoride solution₂Etching and removing to obtain G @ p-NiFe₂O₄I.e. said porous NiFe₂O₄A nanocomposite material.

Step 1, coating porous silicon dioxide (G @ p-SiO) on the surface of the graphene sheet layer₂) The method comprises the following steps: firstly, cetyl trimethyl bromide is addedDissolving ammonium Chloride (CTAB) in H₂O, ethanol and 1.5ml of concentrated aqueous ammonia (H)₂O, ethanol and concentrated ammonia water in the volume ratio of 30:120:1.5), dispersing GO in the mixed solution, slowly adding tetraethyl orthosilicate (TEOS) and keeping the reaction solution to react completely, and then using H to react₂O is washed and dried, and then the product is further annealed for more than 1 hour at the temperature of 300-800 ℃ in inert atmosphere to obtain G @ p-SiO₂And (c) a complex.

According to yet another aspect of the present invention, there is provided a porous NiFe₂O₄Nanocomposite, porous NiFe prepared according to said method₂O₄Use of at least one of the nanocomposites in an electrode material.

According to yet another aspect of the present invention, there is provided a porous NiFe₂O₄Nanocomposite, porous NiFe prepared according to said method₂O₄Use of at least one of the nanocomposites in primary or secondary electrochemical generators, high energy generators, in electrochemiluminescence modulation systems.

According to yet another aspect of the present invention, there is provided a porous NiFe₂O₄Nanocomposite, porous NiFe prepared according to said method₂O₄Use of at least one of the nanocomposites in primary or secondary electrochemical generators, high energy generators, in electrode materials for electrochemiluminescence modulation systems.

According to still another aspect of the present invention, a secondary battery is provided.

The secondary battery is characterized in that the negative electrode material of the secondary battery contains the porous NiFe₂O₄Nanocomposite, porous NiFe prepared according to said method₂O₄At least one of the nanocomposites.

Optionally, the secondary battery includes a lithium ion battery, a sodium ion battery, or a potassium ion battery.

Optionally, the secondary battery comprises a positive electrode, a negative electrode and an electrolyte; the negative electrode includes: a current collector and a negative electrode material supported on the current collector; wherein the negative electrode material contains the composite material.

In the present invention, the "inert atmosphere" refers to at least one of nitrogen and a rare gas.

The beneficial effects that this application can produce include:

1) the invention provides porous NiFe₂O₄The nanocomposite is denoted G @ p-NiFe₂O₄The inner layer is graphene, and the surface of the graphene is coated with NiFe with a porous structure₂O₄In this microstructure, the internal graphene acts as a support for the porous NiFe₂O₄The matrix of the layer and can significantly improve NiFe₂O₄Is used for the electrical conductivity of (1). The more innovative part of the structure is an active ingredient NiFe₂O₄The porous structure is beneficial to rapid ion diffusion and buffering of volume change so as to keep structural stability and high rate performance. Thus, porous NiFe₂O₄The graphene composite material shows more excellent performance as an electrode material of lithium and sodium ion batteries. Especially when the NiFe porous material is used as an electrode material of a sodium ion battery, the ion radius of sodium ions is larger, so that the requirements on ion diffusion and transmission characteristics are higher, and the NiFe porous structure₂O₄In sodium ion battery application, the relative advantages are more prominent. In a lithium ion battery, G @ p-NiFe₂O₄Electrode at 1.5Ag^-1After 1100 charge-discharge cycles at high rate, 240mAh g was still maintained^-1The specific capacity of (A). In sodium ion batteries, at 0.2A g^-1After 300 times of charge and discharge circulation, the specific capacity is still maintained at 207mAh g^-1. These properties are all superior to pure NiFe₂O₄、G@ NiFe₂O₄And (4) comparison materials.

2) The active compound NiFe in the composite material provided by the invention₂O₄The content of the organic silicon compound has very important influence on the performance of the battery, namely directly influencing the specific capacity of the battery and influencing the microstructure of the composite material; active material NiFe for specific capacity of battery₂O₄In an amount ofThe higher the content is, the larger the corresponding theoretical specific capacity is, but the higher the content is, the less the content of graphene is, the conductivity of the electrode is affected, and the performance of the battery is severely restricted; for the microstructure of the composite material, if the active compound NiFe₂O₄If the content of (a) is too high, the graphene cannot play a supporting role, so that the volume of an active substance is changed violently and crushed in the charging and discharging processes, and the performance of the battery is influenced; if the content is too small, the specific capacity of one is too low, and the content and the specific capacity influence the ion transmission speed and the battery performance; in the present invention, the active material NiFe₂O₄The content in the entire composite material is selected from 70% to 90% by weight, and the battery performance is exhibited preferably, and particularly, the performance exhibited most preferably at a content of 87% by weight.

For the active material NiFe₂O₄Firstly, in the invention, the mass of the graphene is reduced due to oxygen radical cracking in the high-temperature annealing reduction process of the used graphene oxide under the inert atmosphere, the mass content of the annealed and reduced graphene is reduced to 58 wt% at 350 ℃, the mass content of the annealed and reduced graphene is gradually reduced along with the continuous increase of the annealing temperature, and the mass content of the annealed and reduced graphene is reduced to 45 wt% at 800 ℃. Therefore, in the invention, the reduction annealing temperature of the graphene and the input ratio of the graphene and the salt can be controlled, and the active substance NiFe in the target product can be accurately controlled₂O₄The content of (a). Of course, as the electrode material, NiFe is the active material₂O₄The higher the content in the whole composite material is expected to be, the better the content is, but the higher the content is, so that the content of graphene is too small, the conductivity is influenced, and finally the battery performance of the material is influenced₂O₄The content in the entire composite material is selected from 70 to 90wt% to exhibit better battery performance, while the content of the most preferable battery performance is 87 wt% to exhibit the most preferable overall battery performance.

Drawings

FIG. 1 is a scheme showing the preparation of G @ p-NiFe₂O₄Schematic of the flow ofIn the figure, scheme 1 shows that the outer surface of the graphene is coated with a porous silicon dioxide layer, and scheme 2 shows that NiFe grows in the inner and outer porous silicon dioxide layers₂O₄Nanoparticles, scheme 3 shows the removal of the porous silica layer by etching to obtain the target product, porous SiO in the figure₂Denotes porous silica, NiFe₂O₄NPs denotes NiFe₂O₄And (3) nanoparticles.

FIG. 2 is the G @ p-NiFe prepared in example 1₂O₄Representative Scanning Electron Micrographs (SEM) and Transmission Electron Micrographs (TEM); wherein, (a) and (b) are scanning electron micrographs, and (c) and (d) are transmission electron micrographs.

FIG. 3 is the G @ p-NiFe prepared in example 1₂O₄Powder X-ray diffraction pattern (XRD) and thermogravimetric pattern (TG) of (a); wherein, (a) is XRD pattern, and (b) is TG pattern.

FIG. 4 is the G @ p-NiFe prepared in example 1₂O₄Lithium ion battery performance of the electrode, at a current density of 1500mAg^-1G @ p-NiFe₂O₄、G@NiFe₂O₄Pure NiFe₂O₄The cycle performance of (c).

FIG. 5 is the G @ p-NiFe prepared in example 1₂O₄Sodium ion Battery Performance of the electrode, G @ p-NiFe₂O₄、G@NiFe₂O₄The electrode was at 200mA g^-1Long term cycling stability.

Detailed Description

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

The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified. The graphene oxide GO is prepared according to the literature (J.Mater.chem.,2011,21, 7376-.

The analysis method in the examples of the present application is as follows:

transmission electron microscopy analysis was performed using a transmission electron microscope (TEM, FEI Inc., USA, Tecnai F20).

Phase analysis of the compounds was performed using an X-ray powder diffractometer (XRD, Rigaku, Miniflex 600).

Scanning electron microscopy was performed using a field emission scanning electron microscope (FESEM, SU-8010, Hitachi, Japan).

Thermogravimetric analysis was performed using a simultaneous thermal analyzer (TG/DTA, STA449F3, Netzsch).

The battery performance test was performed using a battery test system (wuhan blue, CT 3001A).

Example 1

G@p-SiO₂Synthesis of the composite material: 160mg of cetyltrimethylammonium bromide (CTAB) were dissolved in 30ml of H₂O, 120ml ethanol and 1.5ml NH₃.H₂And O in a mixture. Then, 40mg of GO was dispersed in the above solution by ultrasonic waves, and then 1mL of Tetraethylorthosilicate (TEOS) was slowly added and kept stirring for 12 hours. By H₂O washing and drying at 80 ℃, further annealing the product at 800 ℃ for 3 hours under Ar atmosphere to obtain G @ p-SiO₂The composite comprises 6.3 wt% of graphene.

100mg of G @ p-SiO₂(graphene composite with surface coated with porous silica) was added to a solution containing 0.5mmol of Fe (NO)₃)₃·9H₂O and 0.25mmol Ni (NO)₃)₂·6H₂O in 10mL of ethanol. After 10 minutes of sonication, the above solution was stirred at 45 ℃ to evaporate the ethanol. The product was annealed in Ar at 350 ℃ for 3 hours to give G @ SiO₂@NiFe₂O₄Composite of NiFe₂O₄The content was 87 wt%, and was designated as p-N1.

Finally, the prepared G @ SiO₂@NiFe₂O₄Etching with 1M NaOH solution at 50 deg.C for 12 hr to obtain G @ p-NiFe₂O₄And (c) a complex.

And (3) simultaneously putting the product (80 wt%), conductive carbon black (10 wt%) and carboxymethyl cellulose (CMC 10 wt%) into an agate mortar for grinding, wherein deionized water is used as a dispersing agent, and foamed nickel is used as a current collector. And uniformly coating the ground slurry on the weighed dry foamed nickel, drying for 12 hours at 80 ℃ in vacuum, flattening and weighing the electrode plates, and obtaining the mass of the slurry on each electrode plate according to the mass difference before and after coating of the current collector. And continuously vacuum-drying the electrode plates for 2h at 80 ℃, and then putting the electrode plates into a glove box to be assembled with a button cell.

Assembling the button cell in a glove box filled with argon, wherein for a Lithium Ion Battery (LIB), the counter electrode and the diaphragm are respectively a lithium foil and a celgard 2300 membrane, and the electrolyte is 1M LiPF₆In Ethylene Carbonate (EC): ethyl Methyl Carbonate (EMC): dimethyl carbonate (DMC), in a volume ratio of 1: 1: 1; for Sodium Ion Batteries (SIB), the counter electrode was sodium foil, the separator was a glass fiber membrane, and the electrolyte was 1M NaClO in EC₄: diethyl carbonate (DEC) (1: 1 by volume) containing 10% by weight of Fluoroethylene (FEC). The cell was designated B-p-1.

The constant-current charge and discharge test mainly examines the charge and discharge specific capacity, the cycle performance and the rate capability of the lithium/sodium ion half-cell under different current densities. Cyclic voltammetry test at 0.2mV s on an electrochemical workstation (CHI660C)^-1Is performed at the scanning rate of (1).

Example 2

The present embodiment is different from embodiment 1 in that:

G@p-SiO₂synthesis of the composite material: 160mg of cetyltrimethylammonium bromide (CTAB) were dissolved in 30ml of H₂O, 120ml ethanol and 1.5ml NH₃.H₂And O in a mixture. Then, 18.4mg of GO was dispersed in the above solution by ultrasonic waves, and then 1mL of Tetraethylorthosilicate (TEOS) was slowly added and kept stirring for 12 hours. By H₂O washing and drying at 80 ℃, further annealing the product at 800 ℃ for 3 hours under Ar atmosphere to obtain G @ p-SiO₂The composite comprises 3 wt% of graphene.

100mg of G @ p-SiO₂(graphene composite with surface coated with porous silica) was added to a solution containing 0.3mmol of Fe (NO)₃)₃·9H₂O and 0.15mmol Ni (NO)₃)₂·6H₂O in 10mL of ethanol. After 10 minutes of sonication, the above solution was stirred at 45 ℃ to evaporate the ethanol. The product was dried at 300 ℃ under N₂And carrying out medium annealing for 12 hours. Finally, will be preparedG @ SiO of₂ @NiFe₂O₄Etching with 1M NaOH solution at 50 deg.C for 12 hr to obtain G @ p-NiFe₂O₄Composite of NiFe₂O₄The content was 92% by weight, and the product was designated p-N2.

A battery B-p-2 was prepared in the same manner as in example 1, using p-N2.

Example 3

The present embodiment is different from embodiment 1 in that:

G@p-SiO₂synthesis of the composite material: 160mg of cetyltrimethylammonium bromide (CTAB) were dissolved in 30ml of H₂O, 120ml ethanol and 1.5ml NH₃.H₂And O in a mixture. Then, 81.3mg of GO was dispersed in the above solution by ultrasonic waves, and then 1mL of Tetraethylorthosilicate (TEOS) was slowly added and kept stirring for 12 hours. By H₂O washing and drying at 80 ℃, further annealing the product at 800 ℃ for 12 hours under Ar atmosphere to obtain G @ p-SiO₂The composite comprises 12wt% of graphene.

100mg of G @ p-SiO₂(graphene composite with surface coated with porous silica) was added to a solution containing 0.4mmol of Fe (NO)₃)₃·9H₂O and 0.2mmol Ni (NO)₃)₂·6H₂O in 10mL of ethanol. After 10 minutes of sonication, the above solution was stirred at room temperature to evaporate the ethanol. The product was dried at 500 ℃ under N₂Intermediate annealing for 1 hour to obtain G @ SiO₂@NiFe₂O₄A composite, finally preparing the prepared G @ SiO₂@NiFe₂O₄Etching with 1M NaOH solution at 50 deg.C for 12 hr to obtain G @ p-NiFe₂O₄Composite of NiFe₂O₄The content was 80% by weight, and the product was designated p-N3.

A battery B-p-3 was produced in the same manner as in example 1, using p-N3.

Example 4

The present embodiment is different from embodiment 1 in that: the ferric nitrate salt and the nickel nitrate salt were replaced with ferric acetate and nickel acetate, respectively, and the product was designated as p-N4.

A battery B-p-4 was prepared in the same manner as in example 1, using p-N4.

Example 5

The present embodiment is different from embodiment 1 in that: g @ p-SiO₂The annealing temperature in the synthesis of the composite material was 350 ℃ for 24 hours, and the product was designated as p-N5.

A battery B-p-5 was produced in the same manner as in example 1, using p-N5.

Comparative example 1

1) Pure NiFe₂O₄The preparation of (1):

containing 1mmol of Fe (NO) by evaporation₃)₃·9H₂O and 0.5mmol Ni (NO)₃)·2.6H₂O in 10mL ethanol and annealing the mixture at 350 deg.C for 3h under Ar to prepare pure NiFe₂O₄The sample, noted D-p-N1.

2)G@NiFe₂O₄Synthesis of the composite material:

1mmol of Ni (NO)₃)₂·6H₂O and 2mmol Fe (NO)₃)₃·9H₂O was added to 70ml ethanol containing 40mg GO. After stirring for 30 minutes, the pH of the solution was adjusted to 10.0. The resulting mixture was then transferred to a 100mL teflon-lined stainless steel autoclave and held at 180 ℃ for 20 hours. The precipitate was filtered under vacuum, washed with water and ethanol, and dried at 80 ℃ for 12 hours to give G @ NiFe₂O₄The complex, labeled D-p-N2.

The prepared samples are respectively manufactured into button batteries by the same method as that of the embodiment 1, and are marked as D-B-p-1 and D-B-p-2, and the battery performance test is carried out by the same test method.

Example 6 sample characterization and Performance testing

The samples obtained in examples 1-4 and comparative example were characterized and tested for performance.

FIG. 2 is the G @ p-NiFe prepared in example 1₂O₄Representative Scanning Electron Micrographs (SEM) (fig. (a) and (b)), and Transmission Electron Micrographs (TEM) (fig. (c) and (d)). From SEM andas can be seen in the TEM image, NiFe with porous structure₂O₄The nano-particles are coated with graphene and NiFe₂O₄The size of the nano particles is uniform and is concentrated in 3-5 nm; the pore size distribution is concentrated in the range of 1-10 nm. The morphology, particle size and pore size distribution of the samples p-N2-p-N5 are all similar to those of p-N1.

FIG. 3 is the G @ p-NiFe prepared in example 1₂O₄Powder X-ray diffraction pattern (XRD) (a) and thermogravimetric pattern (TG) (b). XRD and electron diffraction pattern prove that the material contains NiFe₂O₄Crystal phase, NiFe can be identified₂O₄The phase of the card is consistent with that of the JCPDS No.10-0325 standard card. The TG plot indicates the NiFe content in the samples prepared in this example 1₂O₄The mass fraction of (a) is 87%. FIG. 4 is the G @ p-NiFe prepared in example 1₂O₄Lithium ion battery performance of the electrode, at a current density of 1500mAg^-1G @ p-NiFe₂O₄(sample p-N1), G @ NiFe₂O₄(sample D-p-N2), pure NiFe₂O₄(sample D-p-N1). At 1.5Ag^-1After 1100 cycles at high rate of G @ p-NiFe₂O₄、G@NiFe₂O₄Respectively keeping 240mA h g and 170mA h g^-1The specific capacity of (A). The cycle performance of the lithium ion batteries prepared by the samples p-N2-p-N5 is similar to that of the sample p-N1.

FIG. 5 is the G @ p-NiFe prepared in example 1₂O₄Sodium ion Battery Performance of the electrode, G @ p-NiFe₂O₄、G@NiFe₂O₄The electrode was at 200mA g^-1Long term cycling stability. At 0.2Ag^-1After 300 cycles at a rate of G @ p-NiFe₂O₄、G@NiFe₂O₄Respectively keeping 207 and 142mA h g^-1The specific capacity of (A). The cycling performance of the sodium ion batteries prepared from samples p-N2-p-N5 was similar to that of sample p-N1.

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. Porous NiFe₂O₄The graphene composite material is characterized by comprising a graphene layer and porous NiFe₂O₄A layer; the porous NiFe₂O₄Coating two surfaces of the graphene layer with layers;

the porous NiFe₂O₄The preparation method of the graphene composite material comprises the following steps:

b) At G @ p-SiO₂Coated with NiFe on both surfaces₂O₄Layer to obtain G @ p-SiO₂ @ NiFe₂O₄；

c）G@p-SiO₂ @ NiFe₂O₄Etching to obtain G @ p-NiFe₂O₄I.e. the porous NiFe₂O₄A graphene composite material;

the step a) comprises the following steps:

a22) dispersing graphene oxide in the solution I, adding a silicon source, reacting, further annealing at 300-800 ℃ for more than 1 hour in an inert atmosphere to obtain G @ p-SiO₂；

The surfactant in the step a21) is a cationic surfactant; the cationic surfactant is at least one selected from alkyl quaternary ammonium salts.

2. Porous NiFe according to claim 1₂O₄Graphene composite material, characterized in that the porous NiFe₂O₄NiFe in the layer₂O₄Has a porous structure and the pore size distribution is 1-10 nm.

3. Porous NiFe according to claim 1₂O₄Graphene composite material, characterized in that the porous NiFe₂O₄Layer opposite to the porous NiFe₂O₄The mass content of the graphene composite material is 80-92 wt%.

4. Porous NiFe according to claim 3₂O₄Graphene composite material, characterized in that the porous NiFe₂O₄Layer opposite to the porous NiFe₂O₄The mass content of the graphene composite material is 85-90 wt%.

5. Porous NiFe according to claim 1₂O₄The graphene composite material is characterized in that in the step a), the G @ p-SiO₂The content of the graphene in the graphene is 3-12 wt%.

6. Porous NiFe according to claim 1₂O₄The graphene composite material is characterized in that the cationic surfactant is selected from at least one of cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride, dodecyl trimethyl ammonium bromide and dodecyl trimethyl ammonium chloride.

7. Porous NiFe according to claim 1₂O₄The graphene composite material is characterized in that the concentration of the surfactant in the solution I in the step a21) is 0.5-1 wt%.

8. Porous NiFe according to claim 1₂O₄The graphene composite material is characterized in that the volume ratio of water, ethanol and ammonia water in the solution I in the step a21) is 1: (3-10): (0.01-0.04).

9. Porous NiFe according to claim 1₂O₄Graphene composite material, characterized by the steps ofa22) Wherein the silicon source is selected from ethyl orthosilicate.

10. Porous NiFe according to claim 1₂O₄The graphene composite material is characterized in that the inert atmosphere in the step a22) is at least one selected from nitrogen and rare gases.

11. Porous NiFe according to claim 1₂O₄Graphene composite material, characterized in that step b) comprises:

g @ p-SiO₂Adding the mixture into a solution containing ferric salt and nickel salt, dispersing uniformly, removing the solvent, and annealing at 300-500 ℃ for more than 1 hour in an inert atmosphere to obtain the G @ p-SiO₂ @ NiFe₂O₄。

12. Porous NiFe according to claim 11₂O₄The graphene composite material is characterized in that the molar ratio of iron in the iron salt to nickel in the nickel salt is 2 (0.1-1).

13. Porous NiFe according to claim 1₂O₄The graphene composite material is characterized by comprising the following steps:

coating porous silicon dioxide on the surface of the graphene sheet layer to obtain a graphene porous silicon dioxide compound, and coating G @ p-SiO₂Is represented by the formula G @ p-SiO₂The content of the graphene in the graphene is 3-12 wt%;

g @ p-SiO₂Adding the mixture into an ethanol solution containing ferric salt and nickel salt, uniformly dispersing, then completely evaporating the ethanol solvent, and annealing the obtained product in an inert atmosphere at the temperature of 300-500 ℃ for more than 1 hour to obtain the G @ SiO₂@NiFe₂O₄A complex;

SiO in the product of the step 2 is dissolved in hot sodium hydroxide solution or hydrogen fluoride solution₂Etching and removing to obtain G @ p-NiFe₂O₄I.e. said porous NiFe₂O₄Graphene composite materials.

14. Porous NiFe according to claim 1₂O₄The graphene composite material is characterized in that the porous NiFe₂O₄The graphene composite material has the following structural general formula: g @ p-NiFe₂O₄；

15. Porous NiFe according to any one of claims 1 to 14₂O₄Application of the graphene composite material in an electrode material.

16. Porous NiFe according to any one of claims 1 to 14₂O₄The graphene composite material is applied to a primary or secondary electrochemical generator, a high-energy generator and an electrochemical luminescence modulation system.

17. Porous NiFe according to any one of claims 1 to 14₂O₄The graphene composite material is applied to electrode materials of primary or secondary electrochemical generators, high-energy generators and electrochemical luminescence modulation systems.

18. A secondary battery, characterized in that the negative electrode material of the secondary battery contains the porous NiFe as claimed in any one of claims 1 to 14₂O₄Graphene composite materials.

19. The secondary battery according to claim 18, wherein the secondary battery comprises a lithium ion battery, a sodium ion battery, or a potassium ion battery.