CN110828787B

CN110828787B - NiFe2O4Nano composite material and preparation method and application thereof

Info

Publication number: CN110828787B
Application number: CN201910953769.8A
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: 2021-09-21
Anticipated expiration: 2039-10-09
Also published as: CN110828787A

Abstract

The invention discloses a NiFe₂O₄Nanocomposite material comprising at least two graphene layers and at least one NiFe layer₂O₄A layer; the NiFe₂O₄Layers are between the graphene layers. The application also discloses a preparation method and application of the composite material. The nanocomposite has excellent electrical properties.

Description

NiFe2O4Nano composite material and preparation method and application thereof

Technical Field

The invention belongs to the field of nano material preparation, and particularly relates to NiFe₂O₄A nano composite material and a 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 372mAh g^-1Low theoretical capacity of (a). Further, Na when inserted into the raw graphite⁺Large ionic radii of (a) lead to poor reversibility. In pursuit of excellenceIron-based Metal Oxides (MOs), including Fe, in the course of making 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 915mAh g^-1. However, these anodes are in the presence of continuous Li⁺Or Na⁺Poor cell performance results from the inherently low conductivity and large volume changes during insertion/extraction. For example, pure NiFe₂O₄The sample exhibited a rapid capacity fade as LIB anode. While carbon materials (including graphene) and NiFe have traditionally been combined₂O₄Simply mixing or cladding strategies still fail to address NiFe₂O₄The pulverization on the surface of the carbon substrate does not provide good charge-discharge cycle performance of the electrode.

Disclosure of Invention

According to one aspect of the present invention, there is provided a NiFe₂O₄A nanocomposite material.

The NiFe₂O₄Nanocomposite material, characterised in that it comprises at least two graphene layers and at least one NiFe layer₂O₄A layer;

the NiFe₂O₄Layers are between the graphene layers.

The NiFe₂O₄The layers are in homogeneous contact with the graphene layer.

Alternatively, the NiFe₂O₄A nano-composite material comprises a first graphene layer and a first NiFe₂O₄Layer, second graphene layer, second NiFe₂O₄A layer and a third graphene layer.

Alternatively, the NiFe₂O₄The nano composite material comprises a first graphene layer and a first NiFe layer from outside to inside₂O₄Layer, second graphene layer, second NiFe₂O₄A layer and a third graphene layer. Optionally, the composite material has the following structural formula: g @ NiFe₂O₄@ G, wherein,g represents graphene, NiFe₂O₄Denotes NiFe₂O₄The compound comprises graphene as the innermost layer and NiFe as the middle layer₂O₄The graphene is coated on the surface of the innermost graphene layer, the outermost graphene layer is graphene coated on the middle NiFe layer₂O₄And (3) an external part.

Alternatively, the NiFe₂O₄NiFe in the layer₂O₄Is nano-particles with the particle size of 3-5 nm.

Alternatively, the NiFe₂O₄NiFe in the layer₂O₄Has a porous structure with pore size distribution of 0.4-100 nm.

Preferably, the NiFe₂O₄NiFe in the layer₂O₄Has porous structure, and pore size distribution of 2.0-6.8nm, preferably concentrated pore size distribution of 2.0nm, 2.5nm, 2.8nm, 3.8nm, 3.9nm, and 6.8 nm.

Alternatively, the NiFe₂O₄Layer opposite to the NiFe₂O₄The mass content of the nano composite material is 50-80 wt%.

Alternatively, the NiFe₂O₄Layer opposite to the NiFe₂O₄The upper limit of the mass content of the nano composite material is selected from 52 wt%, 55 wt%, 57 wt%, 60 wt%, 62 wt%, 65 wt%, 70 wt%, 72 wt%, 73 wt%, 75wt% or 80 wt%; the lower limit is selected from 50 wt%, 52 wt%, 55 wt%, 57 wt%, 60 wt%, 62 wt%, 65 wt%, 70 wt%, 72 wt%, 73 wt% or 75 wt%.

Alternatively, the NiFe₂O₄Layer opposite to the NiFe₂O₄The mass content of the nanocomposite is 70 to 75wt%, and more preferably 73 wt%.

Optionally, the mass ratio of the second graphene layer to (the sum of the first graphene layer and the third graphene layer) is 1: (2-3).

Optionally, the mass ratio of the second graphene layer to (the sum of the first graphene layer and the third graphene layer) is 1: 2. 1: 2.1, 1: 2.2, 1: 2.3, 1: 2.4, 1: 2.5, 1: 2.7, 1: 2.8, 1: 2.9, 1: 3.0 and a range between any two ratios.

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

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

a1) coating NiFe on two surfaces of graphene layer₂O₄Layer, G @ NiFe₂O₄；

b1) At G @ NiFe₂O₄Modifying polyquaternary ammonium salt to obtain G @ NiFe₂O₄-P；

c1) Coating graphene layers on two surfaces of G @ NiFe2O 4-P to obtain G @ NiFe₂O₄@ G, i.e. said NiFe₂O₄A nanocomposite material.

Optionally, step a1) comprises:

a11) adding iron salt and nickel salt into dispersion liquid containing graphene to obtain dispersion liquid I;

a12) adjusting the pH value of the dispersion liquid I to be alkaline, and carrying out hydrothermal reaction to obtain G @ NiFe₂O₄。

Optionally, the iron salt is selected from at least one of ferric nitrate, ferric chloride, ferric sulfate, and ferric carboxylate.

Optionally, the nickel salt is selected from at least one of nickel nitrate, nickel chloride, nickel sulfate and nickel carboxylate.

Optionally, the concentration of iron in the iron salt in the dispersion liquid I is 0.002-0.02 mol/L;

the concentration of nickel in the nickel salt in the dispersion liquid I is 0.001-0.01 mol/L;

the concentration of graphene in the dispersion liquid I is 0.1-1 g/L.

Optionally, the pH of the dispersion liquid I is adjusted to 9-11 in the step a 12).

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

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

Optionally, in step a1), the G @ NiFe₂O₄The content of the graphene in the graphene is 3-12 wt%.

Optionally, in step a1), the G @ p-SiO₂The upper limit of the content of the graphene in (b) is selected from 5wt%, 6.3 wt%, 8 wt%, 10 wt% or 12 wt%; the lower limit is selected from 3 wt%, 5wt%, 6.3 wt%, 8 wt% or 10 wt%.

Optionally, the temperature of the hydrothermal reaction is 150-220 ℃; the time of the hydrothermal reaction is 12-48 hours.

Optionally, in step b1), the G @ NiFe₂O₄The content of the polyquaternium in the-P is 50-75 wt%.

Optionally, the polyquaternary ammonium salt in step b1) is selected from at least one of polydiallyl dimethyl ammonium chloride (PDDA), polydimethyldiallyl ammonium chloride, polymethacrylamidopropyl trimethyl ammonium chloride, polymethacrylamidopropyl dodecyl dimethyl ammonium chloride.

Alternatively, in step b1) the process is described as G @ NiFe₂O₄The polyquaternary ammonium salt modified on the P is G @ NiFe₂O₄Surface adsorption and/or bonding of polyquaternium.

Optionally, step b1) comprises:

to G @ NiFe₂O₄Adding polyquaternary ammonium salt into the dispersion liquid, and carrying out ultrasonic treatment to obtain G @ NiFe₂O₄–P。

Optionally, the time of the ultrasonic treatment is 0.1-1 hour.

Optionally, step c1) comprises:

to G @ NiFe₂O₄Adding a solution containing graphene oxide into the dispersion liquid of the P to ensure that the graphene oxide sheets are coated on the G @ NiFe₂O₄Annealing the surface of the nickel-iron alloy at the temperature of 300-500 ℃ for more than 1 hour in an inert atmosphere to obtain the G @ NiFe₂O₄@ G, i.e. said NiFe₂O₄A nanocomposite;

the inert atmosphere is at least one of nitrogen and rare gas.

Optionally, the concentration of the graphene oxide in the graphene oxide-containing solution in the step c1) is 0.1-1 g/L.

Optionally, the upper limit of the temperature of the annealing in step c1) 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 c1) is 1-12 hours.

Optionally, the upper limit of the time of the annealing in step c1) 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 method is characterized by comprising the following steps:

1、G@NiFe₂O₄preparation of the Complex

The G @ NiFe₂O₄The compound is prepared by loading NiFe on the surface of a graphene sheet layer₂O₄The composite is prepared by the following steps:

uniformly dispersing ferric salt and nickel salt into an ethanol solution containing graphene, adjusting the pH value of the solution to 9-11, carrying out hydrothermal treatment on the solution, filtering, washing and drying the obtained product to obtain the G @ NiFe₂O₄Preparing a compound;

the molar ratio of iron to nickel in the ferric salt and the nickel salt is 2 (0.1-1); the iron salt is selected from ferric nitrate and/or ferric carboxylate, the nickel salt is nickel nitrate and/or nickel carboxylate, and the G @ NiFe₂O₄The content of graphene in the composite is 3-12 wt%;

2. poly diallyl dimethyl ammonium chloride is modified at G @ NiFe₂O₄The surface of the compound is positively charged, and the modification is that the compound is adsorbed or bonded on G @ NiFe₂O₄A surface of the composite;

3. uniformly dispersing the product obtained in the step (2) in water, slowly adding the dispersion liquid into a Graphene Oxide (GO) solution to enable graphene sheets to be fully wrapped on the surface of the product obtained in the step (2), and then placing the obtained product in an inert atmosphere to anneal at the temperature of 300-500 ℃ for more than 1 hour; the inert atmosphere is one or more of nitrogen or rare gas.

Alternatively, the NiFe₂O₄Nanocomposite expressed as G @ NiFe₂O₄@ G, wherein G represents graphene or NiFe₂O₄Denotes NiFe₂O₄The compound comprises graphene as the innermost layer and NiFe as the middle layer₂O₄The graphene is coated on the surface of the innermost graphene layer, the outermost graphene layer is graphene coated on the middle NiFe layer₂O₄Said NiFe₂O₄Are aggregated into nanoparticles.

As a specific embodiment, there is provided a NiFe₂O₄Preparation method of nano composite material, NiFe₂O₄Nanocomposite expressed as G @ NiFe₂O₄@ G, wherein G represents graphene or NiFe₂O₄Denotes NiFe₂O₄The compound comprises graphene as the innermost layer and NiFe as the middle layer₂O₄The graphene is coated on the surface of the innermost graphene layer, the outermost graphene layer is graphene coated on the middle NiFe layer₂O₄Said NiFe₂O₄Are aggregated in the form of nanoparticles; the method comprises the following steps:

1.G@NiFe₂O₄preparation of the complex: the G @ NiFe₂O₄The compound refers to the load of NiFe on the surface of the graphene sheet layer (G)₂O₄The composite is prepared by the following steps: uniformly dispersing ferric salt and nickel salt into an ethanol solution containing graphene, adjusting the pH value of the solution to 10, carrying out hydrothermal treatment on the solution, filtering, washing and drying the obtained product to obtain the G @ NiFe₂O₄Preparing a compound; the 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 iron carboxylate, the nickel salt is one or more of nickel nitrate or nickel carboxylate, and the iron carboxylate and the nickel carboxylate areRefers to the corresponding carboxylate salt which is soluble in ethanol solvent; the G @ NiFe₂O₄The content of graphene in the composite is 3-12 wt%;

2. poly diallyl dimethyl ammonium chloride (PDDA) is modified at G @ NiFe₂O₄The surface of the compound is positively charged, and the modification refers to adsorption or bonding on G @ NiFe₂O₄A surface of the composite;

a2) coating porous SiO on two surfaces of graphene layer₂Layer to obtain G @ p-SiO₂；

b2) At G @ p-SiO₂Coated with NiFe on both surfaces₂O₄Layer to obtain G @ p-SiO₂@ NiFe₂O₄；

c2) At G @ p-SiO₂@NiFe₂O₄Modifying polyquaternary ammonium salt to obtain G @ p-SiO₂@ NiFe₂O₄-P；

d2) At G @ p-SiO₂@NiFe₂O₄Coating graphene layers on two surfaces of the-P, and etching to obtain G @ P-NiFe₂O₄@ G, i.e. said NiFe₂O₄A nanocomposite material.

Optionally, in step a2), the G @ p-SiO₂The content of the graphene in the graphene is 3-12 wt%.

Optionally, in step a2), the G @ p-SiO₂The upper limit of the content of the graphene in (b) is selected from 5wt%, 6.3 wt%, 8 wt%, 10 wt% or 12 wt%; the lower limit is selected from 3 wt%, 5wt%, 6.3 wt%, 8 wt% or 10 wt%.

Optionally, step a2) 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, further annealing at 300-800 ℃ for more than 1 hour in an inert atmosphere to obtain G @ p-SiO₂。

Optionally, the cationic surfactant in step a21) is selected from alkyl quaternary ammonium salts, preferably at least one of Cetyl Trimethyl Ammonium Bromide (CTAB), cetyl trimethyl ammonium chloride, dodecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium 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 to 0.04.

Optionally, the volume ratio of water, ethanol and ammonia water in the solution I in the step a21) is 30:120: 1.5.

Optionally, the silicon source in step a22) is selected from Tetraethylorthosilicate (TEOS).

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 b2) 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 the iron in the iron salt to the nickel in the nickel salt in the step b2) is 2 (0.1-1).

Optionally, the molar ratio of iron in the iron salt and nickel in the nickel salt in step b2) is 2: 1.

Optionally, the concentration of the iron salt in the solution containing the iron salt and the nickel salt in the step b2) 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 in the step b2) is 0.001-0.01 mol/L.

Optionally, G @ p-SiO in step b2)₂The 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 b2) 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 b2) 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.

Optionally, in step c2), the G @ p-SiO₂@NiFe₂O₄The content of the polyquaternium in the-P is 50-75 wt%.

Optionally, the polyquaternary ammonium salt in step c2) is selected from at least one of polydiallyl dimethyl ammonium chloride (PDDA), polydimethyldiallyl ammonium chloride, polymethacrylamidopropyl trimethyl ammonium chloride, polymethacrylamidopropyl dodecyl dimethyl ammonium chloride.

Optionally, said in step c2) is at G @ p-SiO₂@NiFe₂O₄The upper modified polyquaternary ammonium salt is G @ p-SiO₂@NiFe₂O₄Surface adsorption and/or bonding of polyquaternium.

Optionally, step c2) comprises:

to G @ p-SiO₂@NiFe₂O₄Adding polyquaternary ammonium salt into the dispersion liquid, and carrying out ultrasonic treatment to obtain G @ p-SiO₂@NiFe₂O₄–P。

Optionally, the time of the ultrasonic treatment is 0.1-1 hour.

Optionally, step d2) comprises:

d21) to the solution containing G @ p-SiO₂@NiFe₂O₄Adding a solution containing graphene oxide into the dispersion liquid of the P to enable graphene oxide sheets to be wrapped in G @ P-SiO₂@NiFe₂O₄-surface of P, obtaining intermediate I;

d22) annealing the intermediate product I in an inert atmosphere at 300-500 ℃ for more than 1 hour to obtain an intermediate product II; the inert atmosphere is at least one of nitrogen and rare gas;

d23) adding the intermediate product II into a solution containing an etching agent to obtain G @ p-NiFe₂O₄@ G, i.e. said NiFe₂O₄A nanocomposite material.

Optionally, the etchant is selected from at least one of sodium hydroxide and hydrogen fluoride.

Optionally, said step d1) contains G @ p-SiO₂@NiFe₂O₄G @ P-SiO in P-P dispersion₂@NiFe₂O₄The concentration of-P is 0.1-1 mol/L.

Optionally, the concentration of the graphene oxide in the graphene oxide-containing solution in the step d1) is 0.1-1 mol/L.

As an embodiment, the method, step d2), includes:

Alternatively, the NiFe₂O₄Nanocomposite expressed as G @ p-NiFe₂O₄@ G, wherein G represents graphene and p-NiFe₂O₄NiFe representing porous structure₂O₄The compound is prepared from graphene as the innermost layer and NiFe with porous structure as the middle layer₂O₄The graphene is coated on the surface of the graphene layer at the innermost layer, the graphene is coated at the outermost layer, and the graphene is coated on the p-NiFe layer at the middle layer₂O₄Said p-NiFe₂O₄Are aggregated into nanoparticles.

As an embodiment, the method comprises the steps of:

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 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);

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. poly diallyl dimethyl ammonium chloride is modified at G @ SiO₂@NiFe₂O₄The modification refers to adsorption or bonding on G @ SiO on the surface of the composite₂@NiFe₂O₄A surface of the composite;

4. uniformly dispersing the product obtained in the step (3) in water, slowly adding the dispersion liquid into a graphene oxide solution to enable graphene sheets to be fully wrapped on the surface of the product obtained in the step (2), and then placing the obtained product in an inert atmosphere to anneal at the temperature of 300-500 ℃ for more than 1 hour; the inert atmosphere is one or more of nitrogen or rare gas;

5. SiO in the product of the step 4 is dissolved by hot sodium hydroxide solution or hydrogen fluoride solution₂Etching and removing to obtain G @ p-NiFe₂O₄@ G, i.e. said porous NiFe₂O₄A nanocomposite material.

Alternatively, the NiFe₂O₄Nanocomposite expressed as G @ p-NiFe₂O₄@ G, wherein G represents graphene and p-NiFe₂O₄NiFe representing porous structure₂O₄A compound;

the NiFe₂O₄The innermost layer of the nano composite material is graphene, and the middle layer is NiFe with a porous structure₂O₄The graphene is coated on the surface of the graphene layer at the innermost layer, the graphene is coated at the outermost layer, and the graphene is coated on the p-NiFe layer at the middle layer₂O₄Said p-NiFe₂O₄Are aggregated into nanoparticles.

As a specific embodiment, there is provided a NiFe₂O₄Preparation method of nano composite material, NiFe₂O₄Nanocomposite expressed as G @ p-NiFe₂O₄@ G, wherein G represents graphene and p-NiFe₂O₄NiFe representing porous structure₂O₄The compound is prepared from graphene as the innermost layer and NiFe with porous structure as the middle layer₂O₄The graphene is coated on the surface of the graphene layer at the innermost layer, the graphene is coated at the outermost layer, and the graphene is coated on the p-NiFe layer at the middle layer₂O₄Said p-NiFe₂O₄In the form of nanoparticle aggregates, said method comprising the steps of:

1. coating porous silicon dioxide (p-SiO2) on the surface of a graphene sheet layer (G) to obtain a graphene porous silicon dioxide compound, wherein the graphene porous silicon dioxide compound is expressed by G @ p-SiO2, and the content of graphene in the G @ p-SiO2 is 3-12 wt%;

2. adding G @ p-SiO2 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 300-500 ℃ for more than 1 hour to obtain a G @ SiO2@ NiFe2O4 compound, wherein the 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 or nickel carboxylate, and the ferric carboxylate and the nickel carboxylate refer to corresponding carboxylates capable of being dissolved in the ethanol solvent;

3. modifying poly (diallyldimethylammonium chloride) (PDDA) on the surface of the G @ SiO2@ NiFe2O4 compound, wherein the modification refers to adsorption or bonding on the surface of the G @ SiO2@ NiFe2O4 compound;

4. uniformly dispersing the product obtained in the step (3) in water, slowly adding the dispersion liquid into a Graphene Oxide (GO) solution to enable graphene sheets to be fully wrapped on the surface of the product obtained in the step (2), and then placing the obtained product in an inert atmosphere to anneal at the temperature of 300-500 ℃ for more than 1 hour; the inert atmosphere is one or more of nitrogen or rare gas;

5. and (3) etching and removing SiO2 in the product obtained in the step (4) by using a hot sodium hydroxide solution or a hydrogen fluoride solution to obtain G @ p-NiFe2O4@ G, namely the porous NiFe2O4 nano composite material.

The method for coating the surface of the graphene sheet layer with porous silicon dioxide (G @ p-SiO2) in the step 1 comprises the following steps: firstly, Cetyl Trimethyl Ammonium Bromide (CTAB) is dissolved in a mixed solution of H2O, ethanol and 1.5ml of concentrated ammonia water (the volume ratio of H2O to ethanol to concentrated ammonia water is 30:120:1.5), then GO is dispersed in the solution, tetraethyl orthosilicate (TEOS) is slowly added, after the reaction liquid is kept fully reacted, H2O is used for washing and drying, and then the product is placed in an inert atmosphere and is further annealed at 300-800 ℃ for more than 1 hour, so that the G @ p-SiO2 compound is obtained.

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

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

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

According to still another aspect of the present invention, there is provided a secondary battery characterized in that a negative electrode material of the secondary battery contains the NiFe₂O₄Nanocomposite, 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.

The invention provides a NiFe₂O₄The application of the nano carbon composite material in a primary or secondary electrochemical generator, a high-energy generator and an electrochemical luminescence modulation system is used as a negative electrode material to be applied to a lithium ion battery, a sodium ion battery or a potassium ion battery.

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

The invention can produce the beneficial effects that:

1) the invention provides porous NiFe₂O₄The nanocomposite is denoted G @ p-NiFe₂O₄@ G, the innermost layer is graphene, and the middle layer is NiFe with a porous structure₂O₄The graphene is coated on the surface of the graphene layer at the innermost layer, the graphene is coated at the outermost layer, and the graphene is coated on the p-NiFe layer at the middle layer₂O₄In this microstructure, the inner graphene serves as a support for the porous NiFe₂O₄The matrix of the layer. The outer graphene serves as a soft protective layer to prevent the active material from aggregating and collapsing during cycling. In addition, both the innermost graphene layer and the outermost graphene clad layer can obviously 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 nano 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-NiFe₂O₄@ G electrode at 200mAg^-1Can provide 1244mAh g after 300 cycles^-1Has high specific capacity and good rate capability of 563mA h g^-1at 4Ag^-1And the long-term cycling stability is up to 1200 cycles. In sodium ion batteries, it also exhibits a high initial charge capacity (at 50 mAg)^-1467mAh g below^-1) And excellent cycling stability up to 300 cycles. These properties are all superior to pure NiFe₂O₄、 G@p-NiFe₂O₄、G@NiFe₂O₄And G @ NiFe₂O₄@ G comparative material.

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 battery₂O₄The higher the content of the graphene is, the larger the corresponding theoretical specific capacity is, but the higher the content is, the less the content of the graphene is, the conductivity of the electrode is influenced, and the performance of the battery is severely restricted; for the microstructure of the composite material, if the active compound NiFe₂O₄If the content of the graphene is too high, the graphene is not coated in place, 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 the battery is too low, and the unreasonable coating structures of the battery and the battery can 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 50% to 80% by weight, and the battery performance is exhibited preferably, and particularly, the performance exhibited most preferably at a content of 73% by weight.

3) The composite material provided by the invention has NiFe as an active material₂O₄The content of the composite material can be controlled by controlling the charging ratio of the iron salt, the nickel salt and the graphene.

Firstly, in the invention, the mass of the graphene is reduced due to oxygen radical cracking in the high-temperature annealing reduction process of the graphene oxide which is put into use under the inert atmosphere, the mass content of the annealed and reduced graphene at 350 ℃ is reduced to 58 wt%, the mass content is gradually reduced along with the continuous increase of the annealing temperature, and the mass content 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 of the whole composite material is, the better the content is, but the higher the content is, the graphene content is too small, the conductivity is influenced, and the active substance is crushed in the charging and discharging process due to the incomplete graphene coating, so that the final influence is causedBattery Performance of the Material, active Material NiFe in the invention₂O₄The content in the entire composite material is selected from 50 to 80wt% to exhibit more excellent battery performance, and the content of 73 wt% which is the most excellent battery performance, exhibits the most excellent overall battery performance.

4) In the composite material provided by the invention, the ratio of the innermost graphene to the outermost graphene also influences the microstructure coated by the composite material and also influences the performance of the battery, and in the invention, the inner graphene NiFe₂O₄Selecting the ratio of the graphene coated on the outermost layer as 1: (2-3) and shows excellent battery performance.

Drawings

FIG. 1 is a scheme showing the preparation of G @ p-NiFe₂O₄The flow scheme of @ G, wherein the flow scheme 1 shows that the outer surface of the graphene is coated with a porous silicon dioxide layer, and the flow scheme 2 shows that NiFe grows inside and outside the porous silicon dioxide layer₂O₄Nanoparticles, scheme 3 shows on porous silica layer and NiFe₂O₄The graphene layer is coated outside the nano-particles, and the flow 4 shows that the porous silicon dioxide layer is removed by etching to obtain a target product, namely porous SiO in the figure₂Denotes porous silica, NiFe₂O₄NPs denotes NiFe₂O₄And (3) nanoparticles.

FIG. 2 is the G @ p-NiFe prepared in example 1₂O₄A representative Scanning Electron Micrograph (SEM), Transmission Electron Micrograph (TEM), powder X-ray diffraction pattern (XRD), and photoelectron scattering pattern of @ G; wherein, (a) to (b) are SEM pictures, (c) are photoelectron scattering patterns, (d) to (g) are transmission electron microscope pictures, (h) are crystal diffraction patterns, and (i) are XRD patterns.

FIG. 3 is the G @ p-NiFe prepared in example 1₂O₄The thermogravimetric spectrum (e) of @ G and the nitrogen isothermal adsorption curves (f) and (f) are illustrated by pore diameter distribution curves.

FIG. 4 is the G @ p-NiFe prepared in example 1₂O₄The lithium ion battery performance of the @ G electrode; wherein (a) a representative discharge-charge curve in a charge-discharge cycle; (b) at a current density of 200mA g^-1G p-NiFe (R) 2₂O₄@ G ofCycle performance; (c) g @ p-NiFe₂O₄The discharge-charge curves at various rates for the @ G electrode; (d) g @ p-NiFe₂O₄@ G and G @ NiFe₂O₄Rate Performance of the @ G electrode was 0.2Ag^-1To 4Ag^-1(ii) a (e) At 1.5A g^-1At high current density of (2), pure NiFe₂O₄，G@p-NiFe₂O₄，G@NiFe₂O₄，G@NiFe₂O₄@ G and G @ p-NiFe₂O₄Long cycling stability curve for the @ G electrode.

FIG. 5 is the G @ p-NiFe prepared in example 1₂O₄The sodium ion battery performance of the @ G electrode; wherein (a) is a typical discharge and charge curve and (b) is G @ p-NiFe₂O₄@ G at 50mA G^-1Lower cycle performance, (c) G @ p-NiFe at various multiplying powers₂O₄Discharge/charge curves of @ G, (d) G @ NiFe₂O₄@ G and G @ p-NiFe₂O₄@ G at 50-1000mA G^-1(ii) Rate Properties, (d) G @ p-NiFe₂O₄，G@NiFe₂O₄，G@NiFe₂O₄@ G and G @ p-NiFe₂O₄@ G electrode 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.

Unless otherwise specified, the raw materials in the examples of the present application were all purchased commercially, in which

Graphene oxide GO is prepared by the inventors 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).

Specific surface area and pore structure analysis were measured using a fully automated gas physical adsorption apparatus (Autosorb-iQ 2-XR, Congta instruments, USA).

X-ray photoelectron spectroscopy was performed using an X-ray photoelectron spectrometer (XPS, Thermo Fisher, ESCALAB 250 Xi).

Cyclic voltammetry tests were performed using an electrochemical workstation (shanghai chen hua, CHI 660D).

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. Then the obtained G @ SiO₂@ NiFe₂O₄The complex is in 100ml H₂O was sonicated with 1mL polydiallyldimethylammonium chloride (PDDA, 20 wt%, 1.04g/mL) for 1 hour. After stirring for 12 hours, the solution was filtered and washed with 1L H₂O washed and then dried overnight at 80 ℃. Then, 60mg of PDDA modified sample is ultrasonically dispersed in 80mL of H₂To O, then add drop wise to 100mL GO solution (0.1 mg/mL). Stirring 1After hours, the solution was filtered, dried at 80 ℃, and then calcined at 350 ℃ for 2 hours to reduce graphene oxide. Finally, the prepared G @ SiO₂@NiFe₂O₄@ G was etched with 1M NaOH solution at 50 ℃ for 12 hours to give G @ p-NiFe₂O₄@ G composite, the mass ratio of the innermost graphene layer to the outermost graphene layer is 1: 2.4, this product is designated C-1.

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 cells were identified as B-1-Li and B-1-Na.

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. However, the device is not suitable for use in a kitchenThereafter, 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. Then the obtained G @ SiO₂@ NiFe₂O₄The complex is in 100ml H₂Sonicate in O with 1mL polydiallyldimethylammonium chloride (PDDA) for 1 hour. After stirring for 12 hours, the solution was filtered and washed with 1L H₂O washed and then dried overnight at 80 ℃. Then ultrasonically dispersing the PDDA modified sample in 160mL H₂To O, then add dropwise to 103mL GO solution (0.1 mg/mL). After stirring for 1 hour, the solution was filtered, dried at 80 ℃, and then calcined at 350 ℃ for 2 hours to reduce graphene oxide. Finally, the prepared G @ SiO₂@NiFe₂O₄@ G was etched with 1M NaOH solution at 50 ℃ for 12 hours to give G @ p-NiFe₂O₄@ G composite of NiFe₂O₄The content is 80wt%, and the mass ratio of the innermost graphene layer to the outermost graphene layer is 1: 2, this product was designated C-2.

Batteries B-2-Li and B-2-Na were prepared in the same manner as in example 1, using C-2.

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 solution by ultrasonic wavesTo the above solution, 1mL of Tetraethylorthosilicate (TEOS) was then added slowly and the stirring was maintained 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 N₂And (5) annealing for 1 hour. Then the obtained G @ SiO₂@NiFe₂O₄The complex is in 100ml H₂Sonicate in O with 1mL polydiallyldimethylammonium chloride (PDDA) for 1 hour. After stirring for 12 hours, the solution was filtered and washed with 1L H₂O washed and then dried overnight at 80 ℃. Then, 50mg of PDDA modified sample is ultrasonically dispersed in 60mL of H₂To O, then add drop wise to 240mL GO solution (0.1 mg/mL). After stirring for 1 hour, the solution was filtered, dried at 80 ℃, and then calcined at 500 ℃ for 1 hour to reduce graphene oxide. Finally, the prepared G @ SiO₂@NiFe₂O₄@ G was etched with 1M NaOH solution at 50 ℃ for 12 hours to give G @ p-NiFe₂O₄@ G composite of NiFe₂O₄The content is 50 wt%, and the mass ratio of the innermost graphene layer to the outermost graphene layer is 1: 3, the product is designated C-3.

Batteries B-3-Li and B-3-Na were prepared in the same manner as in example 1, using C-3.

Example 4

The present embodiment is different from embodiment 1 in that: and respectively replacing ferric nitrate salt and nickel nitrate salt with ferric acetate and nickel acetate, and recording the product as C-4.

Batteries B-4-Li and B-4-Na were prepared in the same manner as in example 1, using C-4.

Example 5

This example is different from example 1The method is characterized in that: g @ p-SiO₂The annealing temperature in the synthesis of the composite material is 350 ℃ for 24 hours, and the product is marked as C-5.

Batteries B-5-Li and B-5-Na were prepared in the same manner as in example 1, using C-5.

Example 6

G@NiFe₂O₄Synthesis of @ G composite material:

1mmol of Ni (NO)₃)₂·6H ₂O and 2mmol Fe (NO)₃)₃·9H ₂O 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 @ NiFe₂O₄And (c) a complex. For G @ NiFe₂O₄Synthesis of @ G composite G @ NiFe was modified by PDDA using the same procedure as in example 1₂O₄The surface of the composite material is positively charged. 30mg of G @ NiFe after PDDA modification₂O₄ (PDDA@G@NiFe₂O₄) Added to 70mL of H₂In O, sonicate for 5 minutes, then add dropwise to 100mL solution containing 10mg GO. After stirring for 1 hour, the mixture was filtered, dried at 80 ℃ and annealed in Ar at 350 ℃ for 3 hours. The product was designated C-6.

The prepared samples were respectively prepared into button cells, which were marked as B-6-Li and B-6-Na, by the same method as in example 1, and the cell performance was tested by the same test method.

Example 7

The specific procedure was the same as in example 6, except that PDDA @ G @ NiFe₂O₄After the GO solution was added, it was annealed in Ar at 500 ℃ for 1 hour, and the resulting sample was designated C-7.

The prepared samples were respectively prepared into button cells, which were marked as B-7-Li and B-7-Na, by the same method as in example 1, and the cell performance was tested by the same test method.

Comparative example:

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 NiFe₂O₄Sample, noted D-C-1.

2)G@p-NiFe₂O₄Preparing a composite material:

removal of the G @ SiO of example 1 with 1M NaOH₂@NiFe₂O₄SiO in (2)₂Layer, preparation to obtain G @ p-NiFe₂O₄Composite materials, i.e. porous NiFe₂O₄The coated graphene composite material is marked as D-C-2.

3)G@NiFe₂O₄The synthesis of (2):

1mmol of Ni (NO)₃)₂·6H ₂O and 2mmol Fe (NO)₃)₃·9H ₂O 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 vacuum filtered, washed with water and ethanol, and dried at 80 ℃ for 12 hours to give G @ NiFe₂O₄The complex, noted D-C-3.

The samples prepared above were fabricated into coin cells, respectively, as D-B-1-Na and D-B-1-Li, D-B-2-Na and D-B-2-Li, D-B-3-Na and D-B-3-Li, by the same method as in example 1, and the cell performance was tested by the same test method.

Example 8 sample characterization and Performance testing

The samples obtained in examples 1-5 and comparative example were characterized and tested for performance.

FIG. 2 is the G @ p-NiFe prepared in example 1₂O₄Representative Scanning Electron Micrograph (SEM), Transmission Electron Micrograph (TEM), powder X-ray diffraction Pattern (XRD), and photoelectrons of @ G (sample C-1)A scattering pattern, (a) (b) is an SEM picture, (c) is a photoelectron scattering pattern, (d) - (g) are transmission electron micrographs, (h) is a crystal diffraction pattern, and (i) is an XRD pattern; as can be seen from SEM and TEM images, NiFe with porous structure₂O₄The nano-particles are coated by the outer graphene layer, and the NiFe₂O₄The size of the nano particles is uniform and is concentrated in 3-5 nm; 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 number 10-0325 standard card. The appearance and the grain diameter of the samples C-2 to C-7 are similar to those of the sample C-1.

FIG. 3 shows G @ p-NiFe prepared in example 1₂O₄The thermogravimetric photograph (e) of @ G (sample C-1) and the nitrogen isothermal adsorption curve (f) are plotted as pore size distribution curves. The figure shows the NiFe of this example₂O₄The mass fraction of the active carbon is 73 percent, the pore size distribution is between 0.4 and 100nm, the pore size distribution is concentrated and is between 2 and 6.8nm, and the main pore size distribution is 2.0, 2.5, 2.8, 3.8, 3.9 and 6.8 nm. The pore size distribution of samples C-2 to C-7 was similar to that of sample C-1.

FIG. 4 shows G @ p-NiFe prepared in example 1₂O₄The lithium ion battery (example 1, preparation of B-1-Li) performance of @ G electrode. (a) Representative discharge-charge curves over charge-discharge cycles, (b) at a current density of 200mA g^-1G p-NiFe (R) 2₂O₄The cycling behavior of @ G (example 1 preparation of B-1-Li). (c) G @ p-NiFe₂O₄The discharge-charge curves at various rates for the @ G (example 1 preparation of B-1-Li) electrode. (d) G @ p-NiFe₂O₄@ G (preparation of B-1-Li in example 1) and G @ NiFe₂O₄The Rate Performance of the @ G (example 6 preparation of B-6-Li) electrode was 0.2A G^-1To 4Ag^-1. (e) At 1.5A g^-1At high current density of (2), pure NiFe₂O₄Comparative example preparation of D-B-1-Li), G @ p-NiFe₂O₄Comparative example preparation D-B-2-Li), G @ NiFe₂O₄Comparative example preparation D-B-3-Li), G @ NiFe₂O₄@ G (preparation of B-6-Li in example 6) and G @ p-NiFe₂O₄Long cycling stability Curve for the @ G (example 1 preparation of B-1-Li) electrode。G@p-NiFe₂O₄@ G (preparation of B-1-Li in example 1) at 0.2A G^-1After 300 times of circulation, the mixed solution still maintains 1244mA h g^-1The specific capacity of (A). In addition, 1,2,3, and 4A g^-1The specific capacity is 794,700,626, and 563mA h g^-1Has excellent rate performance, and is obviously superior to G @ NiFe of a non-porous structure of a contrast material₂O₄@ G (example 6 preparation of B-6-Li) its rate capability at 1,2,3, 4A G^-1The specific capacities are 575, 460, 388 and 340mAh g respectively^-1(ii) a At 1.5Ag^-1After 1100 cycles at high rate of G @ p-NiFe₂O₄Comparative example preparation D-B-2-Li), G @ NiFe₂O₄(comparative example preparation D-B-3-Li) respectively maintained at 240 mAh g and 170mAh g^-1Specific capacity of, and G @ NiFe₂O₄@ G (preparation of B-6-Li in example 6) and G @ p-NiFe₂O₄@ G (preparation of B-1-Li in example 1) maintained 303, 418mAh G, respectively, after 1200 cycles^-1Specific capacity of (a); g @ p-NiFe₂O₄@ G (example 1 preparation of B-1-Li) maintained a coulombic efficiency of 99% or greater throughout the cycle test; pure NiFe₂O₄Only 145mAh g of electrode is left after 100 charge-discharge cycles^-1The specific capacity of (A).

FIG. 5 shows G @ p-NiFe prepared in example 1₂O₄The sodium ion battery performance of the @ G electrode (example 1 preparation B-1-Na). (a) Typical discharge and charge curves, and (b) G @ p-NiFe₂O₄@ G (preparation of B-1-Na in example 1) at 50mAg^-1The cycle performance of the following. (c) G @ p-NiFe at various multiplying powers₂O₄The discharge/charge curve of @ G (preparation of B-1-Na in example 1). (d) G @ NiFe₂O₄@ G (preparation of B-6-Na in example 6) and G @ p-NiFe₂O₄@ G (preparation of B-1-Na in example 1) at 50-1000mAg^-1Rate performance of (c). (e) G @ p-NiFe₂O₄Comparative example preparation D-B-2-Na), G @ NiFe₂O₄Comparative example preparation D-B-3-Na), G @ NiFe₂O₄@ G (preparation of B-6-Na in example 6) and G @ p-NiFe₂O₄@ G (preparation of B-1-Na in example 1) electrode at 200mAg^-1Long term cycling stability; g @ p-NiFe₂O₄@ G (preparation of B-1-Na in example 1) at 0.05Ag^-1After the next 100 cycles, the liquid is still maintained for 357mA h g^-1The specific capacity of (A). In addition, the content of the active ingredient is 0.15, 0.3, 0.5, 0.8, 1A g^-1The specific capacities of the compounds are respectively 310, 251, 213, 169 and 146mAh g^-1Has excellent rate performance, and is obviously superior to G @ NiFe of a non-porous structure of a contrast material₂O₄@ G (preparation of B-6-Na in example 6) its rate capability at 0.15, 0.3, 1A G^-1The specific capacities are respectively 217, 183 and 127mA h g^-1(ii) a At 0.2Ag^-1After 300 cycles at a rate of G @ p-NiFe₂O₄Comparative example preparation of D-B-2-Na), G @ NiFe₂O₄Comparative example preparation D-B-3-Na), G @ NiFe₂O₄@ G (preparation of B-6-Na in example 6) and G @ p-NiFe₂O₄@ G (preparation of B-1-Na in example 1) was maintained at 207, 142, 211 and 252mA h G, respectively^-1The specific capacity of (A).

The above description is only for the purpose of illustrating the present invention and is not intended to limit the present invention in any way, and the present invention is not limited to the above description, but rather should be construed as being limited to the scope of the present invention.

Claims

1. NiFe₂O₄Nanocomposite material, characterized in that the NiFe₂O₄The nano composite material comprises a first graphene layer and a first NiFe₂O₄Layer, second graphene layer, second NiFe₂O₄A layer and a third graphene layer;

the NiFe₂O₄NiFe in the layer₂O₄The porous structure is provided, and the pore size distribution is 0.4-100 nm;

the NiFe₂O₄The preparation method of the nano composite material comprises the following steps:

c2) At G @ p-SiO₂@ NiFe₂O₄Modifying polyquaternary ammonium salt to obtain G @ p-SiO₂@ NiFe₂O₄-P；

d2) At G @ p-SiO₂@ NiFe₂O₄Coating graphene layers on two surfaces of the-P, and etching to obtain G @ P-NiFe₂O₄@ G, i.e. said NiFe₂O₄A nanocomposite material.

2. NiFe according to claim 1₂O₄Nanocomposite material, characterized in that the NiFe₂O₄NiFe in the layer₂O₄Is nano-particles with the particle size of 3-5 nm.

3. NiFe according to claim 1₂O₄Nanocomposite material, characterized in that the NiFe₂O₄NiFe in the layer₂O₄The pore size distribution of (A) is 2.0-6.8 nm.

4. NiFe according to claim 3₂O₄Nanocomposite material, characterized in that the NiFe₂O₄NiFe in the layer₂O₄The pore diameters of the porous particles are intensively distributed at 2.0nm, 2.5nm, 2.8nm, 3.8nm, 3.9nm and 6.8 nm.

5. NiFe according to claim 1₂O₄Nanocomposite material, characterized in that the NiFe₂O₄Layer opposite to the NiFe₂O₄The mass content of the nano composite material is 50-80 wt%.

6. NiFe according to claim 5₂O₄Nanocomposite material, characterised in thatSaid NiFe₂O₄Layer opposite to the NiFe₂O₄The mass content of the nano composite material is 70-75 wt%.

7. NiFe according to claim 1₂O₄Nanocomposite, its characterized in that, the mass ratio of second graphite alkene layer and first graphite alkene layer and third graphite alkene layer sum is 1: (2-3).

8. NiFe according to claim 1₂O₄Nanocomposite material, characterized in that, in step a2), the G @ p-SiO₂The content of the graphene in the graphene is 3-12 wt%.

9. NiFe according to claim 1₂O₄Nanocomposite material, characterized in that, in step c2), the G @ p-SiO₂@ NiFe₂O₄The content of the polyquaternium in the-P is 50-75 wt%.

10. NiFe according to claim 1₂O₄Nanocomposite, characterized in that step d2) comprises:

d21) to the solution containing G @ p-SiO₂@NiFe₂O₄Adding a solution containing graphene oxide into the dispersion liquid of the P to enable graphene oxide sheets to be wrapped in G @ P-SiO₂@ NiFe₂O₄-surface of P, obtaining intermediate I;

11. NiFe according to claim 1₂O₄Nanocomposite material, characterised in that the packageThe method comprises 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 300-500 ℃ for more than 1 hour to obtain the G @ SiO₂@NiFe₂O₄A complex;

poly diallyl dimethyl ammonium chloride is modified at G @ SiO₂@NiFe₂O₄The modification refers to adsorption or bonding on G @ SiO on the surface of the composite₂@NiFe₂O₄A surface of the composite;

uniformly dispersing the product obtained in the step (3) in water, slowly adding the dispersion liquid into a graphene oxide solution to enable graphene sheets to be fully wrapped on the surface of the product obtained in the step (2), and then placing the obtained product in an inert atmosphere to anneal at the temperature of 300-500 ℃ for more than 1 hour; the inert atmosphere is one or more of nitrogen or rare gas;

SiO in the product of the step 4 is dissolved by hot sodium hydroxide solution or hydrogen fluoride solution₂Etching and removing to obtain G @ p-NiFe₂O₄@ G, i.e. said porous NiFe₂O₄A nanocomposite material.

12. NiFe according to claim 1₂O₄Nanocomposite material, characterized in that said NiFe₂O₄Nanocomposite expressed as G @ p-NiFe₂O₄@ G, wherein G represents graphene and p-NiFe₂O₄NiFe representing porous structure₂O₄A compound;

13. NiFe of any of claims 1 to 12₂O₄Use of a nanocomposite material in an electrode material.

14. NiFe of any of claims 1 to 12₂O₄The application of the nano composite material in primary or secondary electrochemical generators, high-energy generators and electrochemical luminescence modulation systems.

15. NiFe of any of claims 1 to 12₂O₄The application of the nano composite material in the electrode materials of primary or secondary electrochemical generators, high-energy generators and electrochemical luminescence modulation systems.

16. A secondary battery characterized in that a negative electrode material of the secondary battery contains NiFe as defined in any one of claims 1 to 12₂O₄A nanocomposite material.

17. The secondary battery according to claim 16, wherein the secondary battery comprises a lithium ion battery, a sodium ion battery, or a potassium ion battery.