CN114335513A

CN114335513A - Nano material and preparation method and application thereof

Info

Publication number: CN114335513A
Application number: CN202110535717.6A
Authority: CN
Inventors: 刘杨杰; 温珍海
Original assignee: Fujian Institute of Research on the Structure of Matter of CAS
Current assignee: Fujian Institute of Research on the Structure of Matter of CAS
Priority date: 2020-09-30
Filing date: 2021-05-17
Publication date: 2022-04-12
Anticipated expiration: 2041-05-17
Also published as: CN114335513B

Abstract

The invention provides a nano material and a preparation method and application thereof, wherein the nano material comprises a nano sheet; the nanosheet has a chemical formula shown in formula I; MoS_xTe_2‑xFormula I, wherein x is more than or equal to 0 and less than 2; the nano sheets are assembled into a tube centerline hierarchical structure. The invention constructs the tellurium (Te) atom doped MoS_xTe_2‑xThe nano sheets are assembled into a 'tube center line' nano structure, the structure can not only improve the conductivity of the electrode, but also effectively relieve the volume expansion of the electrode in the circulation process, and effectively improve the electrochemical performance of the electrode as a cathode material of a sodium ion bi-ion battery.

Description

Nano material and preparation method and application thereof

Technical Field

The application relates to a nano material and a preparation method and application thereof, belonging to the field of sodium ion batteries.

Background

The sodium-based dual-ion battery is used as a new energy storage device, and has great prospect in various energy storage applications due to the advantages of high working voltage, low cost, environmental friendliness and the like. However, the conventional bi-ion battery is also called as "dual-carbon battery", and the carbon-based material cannot meet the requirement of the sodium-based bi-ion battery with high energy density and high power density, which greatly limits the practical development thereof. The negative electrode material is continuously embedded and separated from larger sodium ions in the charge-discharge cycle process, so that the following problems are easily caused: (1) the traditional carbon material has fewer sodium storage active sites, and the requirement of high energy density is difficult to realize; (2) the negative electrode material is easy to cause volume expansion and pulverization phenomena in the process of sodium insertion and removal; (3) the SEI film formed on the surface of the negative electrode material continuously generates a cycle phenomenon of generation, rupture and regeneration, consumes a large amount of active ions and electrolyte, and causes lower coulombic efficiency. Therefore, the development of a sodium-based bi-ion battery anode material having high specific capacity, long cycle life, and stable structure is the key to solve the above problems.

Recently, compounds having a layered structure (such as molybdenum disulfide, tungsten disulfide, and tin disulfide) have attracted much attention in the field of energy storage batteries because they have a large interlayer distance, which is favorable for the intercalation and deintercalation of sodium ions. Especially molybdenum disulfide based nano material with large interlayer spacing of 0.62nm, provides effective diffusion path for lithium ion intercalation/deintercalation in cycle process, and four-electron transfer occurs in electrochemical reaction process, thus 670mAh g is obtained^-1Is twice as large as the theoretical capacity of the graphite carbon-based anode material. However, molybdenum disulfide electrode materials also face a number of challenges: (1) molybdenum disulfide is used as a semiconductor, and the conductivity of the molybdenum disulfide is poor; (2) the molybdenum disulfide sheet with a layered two-dimensional structure is easy to have a stacking effect, so that the diffusion kinetics of sodium ions are slow; (3) the large volume effect is generated in the charging and discharging process, and the electrode is easy to expand and fall off from the current collector, so that the rapid attenuation of the capacity is caused, and the practical application of the electrode is limited. Therefore, how to improve the stability of the molybdenum disulfide-based nano material through a simple and economic method so as to obtain the molybdenum disulfide-based sodium-based double-ion battery cathode material with excellent performanceIt appears to be of great importance, which is also a difficult problem in current research.

Disclosure of Invention

The invention aims to solve the existing problems and aims to provide a tellurium-molybdenum sulfide nanotube sodium-based bi-ion battery cathode material with a 'tube center line' structure, which is synthesized by taking a tellurium nanotube as a structure induction template and a tellurium atom doping source, and is formed by self-assembling tellurium-molybdenum sulfide nanosheets. The method has the advantages of simple production process, environmental friendliness, high product yield, easy industrial amplification and realization of commercialization.

According to a first aspect of the present application, there is provided a nanomaterial comprising nanoplatelets; the nanosheet has a chemical formula shown in formula I;

MoS_xTe_2-xformula I

Wherein x is more than or equal to 0 and less than 2;

the nano sheets are assembled into a tube centerline hierarchical structure.

Preferably, the nanoplatelets have the chemical formula MoS_1.5Te_0.5。

Optionally, in the tube centerline structure, the length of the tube is 8-12 μm; the outer diameter of the tube is 500-600 nm; the inner diameter of the tube is 250-350 nm;

the length of the wire is 6-10 μm; the diameter of the wire is 80-120 nm.

Optionally, the particle size of the nano-sheet is 100-200 nm.

Optionally, in the nanomaterial, carbon is further included;

the carbon is supported on the surface of the nanosheet.

Optionally, in the nanomaterial, the mass content of the carbon is 10-20 wt%.

Optionally, in the nanomaterial, the upper limit of the mass content of the carbon is independently selected from 20 wt% and 15 wt%, and the lower limit is independently selected from 10 wt% and 15 wt%.

According to a second aspect of the present application, there is provided a method for preparing the above-mentioned nanomaterial, the method comprising:

(1) obtaining a Te nano tube;

(2) reacting materials containing the Te nano tube, a molybdenum source and a sulfur source I to obtain a precursor;

(3) and (3) reacting the precursor in a hydrogen-containing atmosphere to obtain the nano material.

Optionally, the precursor is of a rod-shaped structure, and the length of the precursor is about 8-12 μm; the diameter is 500 to 600 nm.

Optionally, the preparation method comprises:

a) obtaining a Te nano tube;

b) placing the Te nano-tube in a composite solution containing inorganic molybdenum salt, an inorganic sulfur source compound and an organic surfactant A to obtain a solution A;

c) putting the solution A into an oil bath pan, reacting for 10-24 hours at 180-200 ℃, separating and drying to obtain a precursor;

d) and (3) placing the precursor in a mixed gas of hydrogen and argon, heating to 600-900 ℃ at a heating rate of 0.5-10 ℃/min, and preserving heat for 1-4 hours to obtain the nano material.

Optionally, the molybdenum source is selected from at least one of molybdenum salts;

the sulfur source is at least one selected from thiourea, thioacetamide and cysteine.

Optionally, the conditions of reaction I are: the temperature is 180 ℃ and 200 ℃; the time is 10-24 h;

the conditions of the reaction II are as follows: the temperature is 600-900 ℃; the time is 1-4 h.

Optionally, the mass ratio of the Te nano-tube to the molybdenum source to the sulfur source is 1: 0.5-6: 1-12.

Optionally, the Te nanotubes are obtained by the following method:

and reacting III with a mixture containing tellurium dioxide, a surfactant B and an alkali source to obtain the Te nano tube.

Specifically, the surfactant B serves as a soft template in the solution to induce the tellurium source in the solution to uniformly and regularly generate the tellurium nanotubes.

Optionally, the conditions of reaction III are: the temperature is 180-220 ℃; the time is 0.5-4 h.

Preferably, the mass ratio of the molybdenum source to the sulfur source to the surfactant A is 3: 6: 1.

optionally, the Te nanotubes are obtained by the following method:

adding tellurium dioxide into 100-200 mL of solvent I, heating to 180-220 ℃ at a heating rate of 1-10 ℃/min, adding 0.5-2 g of sodium hydroxide, continuously reacting for 0.5-4 hours at the temperature, separating, and drying to obtain a gray solid, namely the Te nano tube.

Optionally, in the mixture, a solvent I is further included; the solvent I is selected from alcohol compounds.

In the present application, the Te nanotubes serve both as structure-inducing frameworks and as Te atom doping sources.

Preferably, the carbon is a carbon film.

Preferably, the alcohol compound is selected from ethylene glycol.

Optionally, the alkali source is selected from at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide;

the surfactant B is selected from cationic surfactants.

Preferably, the cationic surfactant is selected from at least one of polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, cetyltrimethylammonium bromide, and polydiallyldimethylammonium chloride. Optionally, a solvent is also included in the material;

the solvent is at least one selected from water, alcohol compounds, N-dimethylformamide, N-hexane, cyclohexane, octadecenylamine, oleic acid and oleylamine;

preferably, the alcohol compound is at least one selected from methanol, ethanol, isopropanol and ethylene glycol.

Optionally, the material also comprises a surfactant A;

the surfactant A is at least one selected from glucose, cetyl trimethyl ammonium bromide and polyvinylpyrrolidone.

Optionally, the mass ratio of the sulfur source to the surfactant A is 1: 0.01-1.

According to a third aspect of the present application, there is provided an anode material comprising at least one of the nanomaterial described above, the nanomaterial prepared according to the method described above.

According to a final aspect of the application, there is provided a use of at least one of the above-mentioned anode materials in a sodium ion battery.

The invention has the beneficial effects that: the structure prepared by the method is stable, and the electrochemical performance is excellent; in addition, the method has the advantages of simple production process, environmental friendliness, high product yield, easy industrial amplification and realization of commercialization.

Drawings

FIG. 1 is a schematic diagram of the preparation process of the nanomaterial provided by the present invention.

FIG. 2 is an X-ray diffraction pattern of the product obtained by the preparation process of example 1 of the present invention.

FIG. 3 is a field emission scanning electron micrograph of the product obtained by the preparation process of example 1 of the present invention.

FIG. 4 is an SEM image of a precursor prepared in example 1 of the present invention.

FIG. 5 is a transmission electron microscope image of the product obtained by the preparation process of example 1 of the present invention.

FIG. 6 is a graph showing electrochemical cycle performance of an electrode material prepared by the preparation process of example 1 of the present invention.

FIG. 7 is a graph of electrochemical rate performance of the electrode material prepared by the preparation process of example 1 of the present invention.

Fig. 8 is an SEM image of the precursor prepared in example 4.

Fig. 9 is an SEM image of the precursor prepared in example 5 (where a and b are SEM images at different magnifications, respectively).

Fig. 10 is an SEM image of the precursor prepared in example 2.

Fig. 11 is an SEM image of the precursor prepared in example 6.

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 present invention is further described by the following embodiments with reference to the drawings, but it should be noted that the embodiments do not limit the scope of the present invention.

Fig. 1 is a schematic diagram of a preparation process of a nanomaterial provided by the present invention, and a tellurium nanotube is prepared first, then a carbon-loaded molybdenum disulfide nanosheet grows inside and outside the tellurium nanotube, and finally the nanomaterial in the present application is obtained by reaction in a reducing atmosphere.

The instrument models used in the examples of this application are shown in table 1 below:

example 1

1. Pretreating raw materials;

placing 1.44g of tellurium dioxide, 1.8g of polyvinylpyrrolidone (K30) and 150mL of ethylene glycol solution into a 250mL round-bottom flask, stirring for 30min at 130 ℃, uniformly heating to 200 ℃ at a heating rate of 5 ℃/min, then rapidly adding 0.9g of sodium hydroxide, continuously stirring for 2h at 200 ℃, and then centrifugally drying to obtain the tellurium nanotube.

2. Preparing a precursor;

dissolving 50mg of the prepared tellurium nanotubes, 100 mgD-glucose, 150mg of sodium molybdate and 300mg of thiourea in 30ml of deionized water solvent, carrying out ultrasonic treatment for half an hour, putting the obtained mixed solution into a reaction kettle, transferring the mixed solution into an oil bath kettle, reacting for 10 hours at 180 ℃, and carrying out centrifugal drying on a product after the reaction is finished to obtain a black solid powder precursor;

3. a calcination process;

heating the black solid powder precursor obtained in the step 2 to 800 ℃ at a heating rate of 3 ℃/min in a tubular furnace of a mixed atmosphere of hydrogen and argon (10% by volume of hydrogen), preserving heat for 2h, and naturally cooling to room temperature after complete reaction to obtain the nano material (the nano sheet is MoS)_1.5Te_0.5The particle size is 100 to 150 nm).

Performing SEM test on the precursor prepared in the step 2, wherein the result is shown in FIG. 4, and it can be seen from the figure that molybdenum disulfide nanosheets uniformly grow on the inner and outer surfaces of the Te nanotube to form a one-dimensional rod-like structure, the length of the one-dimensional rod-like structure is about 8-12 μm, and the diameter of the one-dimensional rod-like structure is about 500-600 nm; the particle size of the surface nano-sheet is about 100-150 nm.

XRD (X-ray diffraction) tests are carried out on the prepared nano material, figure 2 is an X-ray diffraction pattern of a product, and as can be seen from the figure, the pattern shows obvious (002), (100), (103) and (110) characteristic diffraction peaks at the positions of 11.9 degrees, 32.6 degrees, 38.5 degrees and 57.2 degrees, and the characteristic diffraction peaks and the hexagonal phase crystal form MoS₂The characteristic peak of (1) is in accordance with (JCPDS card number is 37-1492), wherein the diffraction peak of the (002) crystal face shifts to a low angle, which shows that the crystal face spacing of the (002) crystal face is expanded to 0.75 nm. The reason for this is that large-sized tellurium atoms dope and replace part of sulfur atoms, forcing dislocation and slip to occur in the (002) crystal lattice, resulting in the (002) crystal spacing being enlarged.

SEM test is carried out on the prepared nano material, and figure 3 is a field emission scanning electron microscope image of the product, and as can be seen from the image, the product presents a regular tubular structure, the length of the tube is about 10 μm, the outer diameter of the tube is about 550nm, the inner diameter of the tube is about 300nm, the length of the wire is about 8 μm, and the diameter of the wire is about 100 nm. The surface of the tube is a MoS of a single sheet-like structure_1.5Te_0.5The nano sheets are regularly stacked, and a remarkable nano wire is arranged in each tube, and a tube center line composite structure with a hollow structure can be clearly observed.

TEM test is carried out on the prepared nano material, and FIG. 5 is a transmission electron microscope electron micrograph of the product, and as can be seen from the micrograph, the nanowire in the structure is positioned in the middle of the nanotube to form a tube centerline composite structure.

The nanomaterial obtained by the preparation was subjected to TGA test, and the mass content of carbon therein was measured to be 9.1%.

4. A performance test process;

grinding the obtained powder to prepare a negative electrode plate, matching the negative electrode plate with a positive electrode, and assembling the button type sodium-based bi-ion battery, wherein the method comprises the following specific steps:

1) preparing a negative electrode plate: grinding active material powder (namely the nano material prepared by the method), a conductive agent (Super P) and a binder (carboxymethyl cellulose cmc) uniformly according to the mass ratio of 8:1:1, adding a small amount of deionized water to prepare slurry, coating the slurry on a copper foil by using a film coating device, and then preserving heat for 24 hours at 120 ℃ in a vacuum drying oven. And then cutting the dried electrode slice into an electrode slice with the diameter of 12mm by a slicer to be used as a negative electrode slice.

2) Preparing a positive electrode plate: uniformly grinding the expanded graphite, the conductive agent (Super P) and the binder (polyvinylidene fluoride PVDF) according to the mass ratio of 8:1:1, adding a small amount of N-methyl pyrrolidone to prepare slurry, coating the slurry on an aluminum foil by using a film coating device, and then preserving the temperature of the aluminum foil for 24 hours in a vacuum drying oven at 120 ℃. Then, the dried electrode sheet was cut into an electrode sheet having a diameter of 12mm by a slicer to serve as a positive electrode sheet.

3) 3mol/L sodium hexafluorophosphate is weighed in a glove box and added into a mixed solvent of Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and dimethyl carbonate (DMC) in a volume ratio of 1:1:1 to prepare 3M sodium hexafluorophosphate electrolyte.

4) And in a glove box, sequentially assembling the prepared cathode material, the anode material, the electrolyte, the glass fiber diaphragm and the battery shells of the anode and the cathode according to a certain sequence, and finally packaging to complete the button type sodium-based bi-ion battery.

The prepared button sodium-based bi-ion battery is subjected to cycle performance test, fig. 6 is an electrochemical cycle performance diagram of the prepared electrode material, and as can be seen from the diagram, when the current density is set to be 0.1A/g, the first-loop specific discharge capacity and the initial coulombic efficiency are 377.7mAh/g and 57.9%, after 200 deep charge-discharge cycles are performed, the material is stable in specific discharge capacity of 218.6mAh/g, the coulombic efficiency is 97%, and the sodium-based bi-ion battery shows good cycle stability. The lower coulombic efficiency of the first cycle is attributed to the generation of a solid electrolyte interface film (SEI), resulting in irreversible loss of capacity. With continuous charge and discharge cycles, the SEI film tends to be stable, and coulombic efficiency is increasing continuously.

The prepared button sodium-based bi-ion battery is subjected to rate performance test, fig. 7 is an electrochemical rate performance graph of the prepared electrode material, and as can be seen from the graph, the charge-discharge specific capacity is stable at 218mAh/g after 10 times of charge-discharge under the current density of 0.1A/g. As the current density is gradually increased to 0.2A/g, 0.5A/g, 1A/g, 2A/g and 5A/g, the charge and discharge capacity of the sodium-based double-ion battery is slowly reduced and finally reduced to 101 mAh/g. When the current density is set to be 0.1A/g of small multiplying power for continuous operation, the charging and discharging specific capacity is equivalent to the initial specific capacity, and the capacity tends to be stable in the following operation, which indicates that the MoS of the tube midline structure_1.5Te_0.5The composite material exhibits excellent rate performance.

Example 2

Preparation of carbon-free film MoS_1.5Te_0.5The tubular line structured nanocomposite was prepared in the same manner as in example 1, except that D-glucose was not added during the precursor preparation in example 1.

SEM test of the precursor prepared in this example showed that, as shown in fig. 10, the surface of the Te nanotube cannot uniformly grow nanosheets due to the absence of surfactant, and a large number of small spheres formed by the nanosheets independently agglomerated fall on the surface of the precursor.

Example 3

Preparation of carbon-free film MoS_xTe_2-x(where x is 0, i.e. MoTe)₂) The preparation process of the nanocomposite material with a line structure in a tube was the same as in example 1, except that high-purity hydrogen was used as a reaction atmosphere only during the calcination process in example 1.

Example 4

The preparation method of this example is the same as that of example 1, except that: the mass ratio of the Te nano-tube to the molybdenum source to the sulfur source is 1:0.5: 1.

SEM test of the precursor prepared in the embodiment shows that the particle size of the nanosheet is 100-200nm and the nanosheet is thin as shown in FIG. 8.

Example 5

The preparation method of this example is the same as that of example 1, except that: the mass ratio of the Te nano-tube to the molybdenum source to the sulfur source is 1:6: 12.

SEM tests of the precursor prepared in this example show that the nano-sheets on the surface of the Te nanotube exhibit significant agglomeration as shown in fig. 9a and b. As can be seen from the 9b diagram, the particle size of the nano-sheet is 400-500nm, the density of the surface nano-sheet is high, and simultaneously, a rodlike shape of a plurality of Te nano-tubes wrapped by the nano-sheet exists.

Example 6

The preparation method of this example is the same as that of example 1, except that: the mass ratio of the sulfur source to the surfactant A is 1: 1.

SEM test of the precursor prepared in this embodiment shows that as shown in FIG. 11, due to the excessive surfactant, Te nanotubes can uniformly grow nanosheets, the particle size of the nanosheets on the surface of the precursor is 100-200nm, and the density between the nanosheets is increased.

In summary, the present invention is only illustrated by the embodiments and not limited in any way, and although the present invention has been disclosed by the preferred embodiments and not limited in any way, those skilled in the art can make many variations and modifications without departing from the scope of the present invention.

Claims

1. A nanomaterial, characterized in that the nanomaterial comprises nanoplatelets; the nanosheet has a chemical formula shown in formula I;

MoS_xTe_2-xformula I

Wherein x is more than or equal to 0 and less than 2;

the nano sheets are assembled into a tube centerline hierarchical structure.

2. The nanomaterial of claim 1, wherein in the tube-in-line structure, the length of the tube is 8-12 μm; the outer diameter of the tube is 500-600 nm; the inner diameter of the tube is 250-350 nm;

the length of the wire is 6-10 μm; the diameter of the wire is 80-120 nm.

3. The nanomaterial according to claim 1, wherein the nanosheets have a particle size of 100-200 nm.

4. The nanomaterial according to claim 1, further comprising carbon;

the carbon is supported on the surface of the nanosheet.

5. Nanomaterial according to claim 4, characterized in that the carbon content in the nanomaterial is 10-20 wt%.

6. The method for preparing nanomaterials of any one of claims 1 to 5, wherein the method comprises:

(1) obtaining a Te nano tube;

7. The method of claim 6, wherein the molybdenum source is selected from at least one of molybdenum salts;

8. The method according to claim 6, wherein the conditions of reaction I are as follows: the temperature is 180 ℃ and 200 ℃; the time is 10-24 h;

the conditions of the reaction II are as follows: the temperature is 600-900 ℃; the time is 1-4 h;

preferably, the mass ratio of the Te nano-tube to the molybdenum source to the sulfur source is 1: 0.5-6: 1-12;

preferably, the Te nanotubes are obtained by the following method:

reacting III a mixture containing tellurium dioxide, a surfactant B and an alkali source to obtain the Te nano tube;

preferably, the conditions of the reaction III are: the temperature is 180-220 ℃; the time is 0.5-4 h;

preferably, the alkali source is selected from at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide and calcium hydroxide;

the surfactant B is selected from cationic surfactants;

preferably, the cationic surfactant is selected from at least one of polyvinylpyrrolidone, sodium dodecylbenzene sulfonate, cetyl trimethyl ammonium bromide and polydiallyldimethyl ammonium chloride;

preferably, in the material, a solvent is also included;

preferably, the material also comprises a surfactant A;

the surfactant A is at least one selected from glucose, cetyl trimethyl ammonium bromide and polyvinylpyrrolidone;

preferably, the mass ratio of the sulfur source to the surfactant A is 1: 0.01-1.

9. An anode material, characterized in that the anode material comprises at least one of the nanomaterials of any one of claims 1 to 5 and nanomaterials prepared by the method of any one of claims 6 to 8.

10. Use of at least one of the negative electrode materials of claim 9 in a sodium ion battery.