CN110676441A

CN110676441A - Battery negative electrode material, sodium ion battery and preparation method thereof

Info

Publication number: CN110676441A
Application number: CN201810718296.9A
Authority: CN
Inventors: 胡翔; 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: 2018-07-03
Filing date: 2018-07-03
Publication date: 2020-01-10
Anticipated expiration: 2038-07-03
Also published as: CN110676441B

Abstract

The application discloses a battery anode material which is three-dimensional ordered porous carbon-limited Co₉S₈Composite of quantum dots, wherein quantum dot-sized Co₉S₈Confined in the carbon layer, forming a three-dimensionally ordered porous structure. The application also discloses a preparation method of the battery cathode material, which comprises the following steps: 1) obtaining SiO₂A template ball; 2) obtaining a precursor cobalt oleate; 3) subjecting the SiO₂Mixing the template ball and the precursor cobalt oleate with thiourea and oleylamine, and calcining; 4) etching the silicon dioxide template at room temperature by using the mixture calcined in the step 3) to obtain the composite material. The invention also discloses a sodium ion battery and a sodium ion batteryThe preparation method of the sodium ion battery is described.

Description

Battery negative electrode material, sodium ion battery and preparation method thereof

Technical Field

The application relates to a battery cathode material, a sodium-ion battery and a preparation method thereof, belonging to the field of sodium-ion battery materials.

Background

The application of lithium ion batteries has been developed from portable electronic equipment application to the use of large-capacity and high-power electric bicycles, electric automobiles, green power grids and the like. However, the lithium resource is bound to face the shortage problem, and the lithium is expensive and the content of the lithium in the earth crust is low, which may become an important problem for developing a long-life energy storage battery for large-scale energy storage. In view of this, there is an urgent need for developing a novel long-life energy storage device having low cost and excellent performance. Compared with lithium element, the metal sodium element of the same main group has similar physicochemical properties, and also has the advantages of abundant resources, low price, wide distribution and the like, so that the sodium-ion battery is closely concerned by people in the face of large-scale requirements on renewable energy storage application. However, sodium ions are heavier in mass and have a larger radius (0.102nm) than lithium (0.069nm), which not only makes it more difficult for sodium ions to be inserted into and extracted from the electrode material, but also makes it easy for sodium ions to cause structural damage to the active material during the insertion reaction, which affects the cycle stability of the battery. Therefore, the development of sodium ion batteries with high specific capacity and long cycle life is the most important research direction.

More recently, metal sulfides such as cobalt sulfide, CoS₂、Co₃S₄And Co₉S₈And the like have received extensive attention in the field of lithium ion batteries, which benefit from their high theoretical specific capacities. However, Co₉S₈Little research has been done in sodium ion batteries, probably because sodium ions are larger in diameter than lithium ions, resulting in Co-ion interactions₉S₈The volume expansion caused by the alloying reaction is larger, and the diffusion dynamics of a schottish bar is generated, so that the specific capacity is quickly attenuated, and the practical application of the alloy is limited. Therefore, how to improve Co by a simple and economical method₉S₈Stability in sodium ion batteries, thereby obtaining Co with excellent performance₉S₈The cathode material of the sodium-ion battery is very important, which is also a difficult problem in current research.

Disclosure of Invention

According to one aspect of the application, a battery anode material is provided, and the material is three-dimensional ordered porous carbon-limited Co₉S₈Composite of quantum dots, wherein quantum dot-sized Co₉S₈Confined in the carbon layer, forming a three-dimensionally ordered porous structure.

The material is spherical with the particle size of 100-300 nm.

The battery cathode material is prepared by adding quantum dot-sized Co₉S₈Confined in the carbon layer and constructed into a three-dimensional ordered porous structure, the three-dimensional porous structure not only improves Co₉S₈Is Co, and has excellent rate performance₉S₈The volume expansion generated in the circulation process provides an effective buffer space, and good circulation stability is obtained; in addition, the three-dimensional porous structure is favorable for the electrolyte to permeate into the electrode, greatly reduces the diffusion path of sodium ions, and can be used with more Co₉S₈The contact of the active materials provides guarantee for high specific capacity, thereby greatly improving the electrochemical performance of the active materials as the negative electrode materials of the sodium-ion batteries.

According to another aspect of the present application, there is provided a method for preparing the battery anode material, the method comprising the steps of:

1) obtaining SiO₂A template ball;

2) obtaining a precursor cobalt oleate;

3) subjecting the SiO₂Mixing the template ball and the precursor cobalt oleate with thiourea and oleylamine, and calcining;

4) etching the silicon dioxide template at room temperature by using the mixture calcined in the step 3) to obtain the composite material.

According to the method, a cobalt oleate precursor is used as a cobalt source, thiourea is used as a sulfur source and a nitrogen source, in-situ nitrogen doping is carried out on an oleic acid ligand chain while cobalt oleate is subjected to high-temperature vulcanization, and nitrogen-doped Co with the size of carbon-limited quantum dots is obtained₉S₈(ii) a The composite material is finally prepared into a three-dimensional ordered porous structure by taking silicon dioxide as a template, the conductivity of the material can be greatly improved by the composite material structure, and meanwhile, the three-dimensional porous structure can well inhibit Co₉S₈The volume expansion of the electrolyte is reduced, and excellent electrochemical performance is obtained.

Preferably, the SiO₂The template sphere was prepared by the following method:

in BAdding ammonia water and tetraethyl orthosilicate into a mixed solution of alcohol and water, stirring at 20-40 ℃, and centrifugally drying to obtain SiO₂And (4) template balls.

The ammonia water is 25-28% ammonia water solution.

The volume ratio of the ethanol to the water to the ammonia water to the ethyl orthosilicate is as follows:

ethanol: water: the ammonia water is 30-40: 3-8: 1-5.

Preferably, the volume ratio of the ethanol to the water to the ammonia water to the ethyl orthosilicate is as follows:

ethanol: water: ammonia 35:5: 3: 2.8.

preferably, the precursor cobalt oleate is prepared by the following method:

dissolving cobalt chloride and sodium oleate in a solution of ethanol, water and hexane, and refluxing for 3-5 h. Those skilled in the art can select an appropriate reflux temperature within a temperature range in which reflux can be formed, according to actual needs. Preferably, the reflux temperature is 70 ℃.

Preferably, in the step 3), SiO₂The template ball comprises a precursor cobalt oleate, thiourea and oleylamine according to the mass ratio of (0.3-0.7): (0.1-0.5): 1: (1.2-2).

Preferably, the calcination process in step 3) is: heating to 700-800 ℃ at a heating rate of 3-10 ℃/min, and then preserving the heat for 1.5-3 h.

Preferably, the heating rate is 5-7 ℃/min. Preferably, the etching is performed in a NaOH solution, and the concentration of the NaOH solution is 1.2-2.5 mol/L.

According to another aspect of the present application, there is provided a sodium ion battery, wherein the negative electrode material of the sodium ion battery is the battery negative electrode material or the negative electrode material prepared by using the method.

According to another aspect of the present application, there is provided a method for preparing a sodium-ion battery, the method comprising:

mixing the sodium ion battery negative electrode material with a conductive agent and a binder to prepare slurry, coating the slurry on copper foil, drying, cutting into electrode plates, and assembling into a battery.

Preferably, the mass ratio of the battery negative electrode material to the conductive agent and the binder is (6-10): (0.5-1.5): 1.

the beneficial effects that this application can produce include:

1) the composite material structure provided by the application can greatly improve the conductivity of the material, and meanwhile, the three-dimensional porous structure can well inhibit Co₉S₈The volume expansion of the catalyst is realized, and excellent electrochemical performance is obtained;

2) the sodium ion battery provided by the application has high battery capacity and good cycle performance;

3) the sodium ion battery provided by the application has excellent sodium storage performance;

4) the preparation method provided by the application has the advantages of simple process, environmental friendliness, high product yield, easiness in industrial amplification and realization of commercialization.

Drawings

FIG. 1 is an X-ray diffraction pattern of the product obtained in example 1 of the present invention.

FIG. 2 is a field emission scanning electron micrograph of the product obtained in example 1 of the present invention.

FIG. 3 is an SEM image of the product obtained in example 1 of the present invention.

FIG. 4 is a high resolution TEM image of the product obtained in example 1 of the present invention.

Fig. 5 is a graph of electrochemical cycle performance of the electrode material prepared in example 1 of the present invention.

Fig. 6 is a graph of electrochemical rate performance of the electrode material prepared in example 1 of the present invention.

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

in the examples, transmission electron microscopy of the samples was characterized using a high resolution transmission electron microscope (Tecnai F20).

In the examples, the scanning electron microscope of the sample was characterized by using a Hitachi SU-8020 model field emission scanning electron microscope.

In the examples, X-ray diffraction analysis (XRD) of the samples was characterized using Miniflex 600.

In the examples, the electrochemical performance of the sodium-ion cell of the button type was tested using an electrochemical workstation model CHI760E from chenhua corporation, shanghai.

Example 1

1. Preparing a template;

adding 3ml of ammonia water into a mixed solution of 35ml of ethanol and 5ml of deionized water, stirring for 30min at the temperature of 30 ℃, then adding 2.8ml of tetraethyl orthosilicate, continuously stirring for 6h at the temperature of 30 ℃, and then centrifugally drying to obtain SiO₂And (4) template balls.

2. Preparing a precursor;

dissolving 14.3g of cobalt chloride hexahydrate and 36.5g of sodium oleate in a mixed solution of 80ml of ethanol, 60ml of water and 140ml of hexane, carrying out ultrasonic treatment for half an hour, refluxing the obtained mixed solution in an oil bath kettle at 70 ℃ for 4 hours, and separating out organic layer cobalt oleate after the reaction is finished.

3. A calcination process;

0.5g of cobalt oleate, 300mg of silica template spheres, 1g of thiourea and 2ml of oleylamine are uniformly mixed for 1h, finally, the obtained viscous mixture is placed in a tubular furnace in argon atmosphere, the temperature is raised to 750 ℃ at the heating rate of 5 ℃/min, the temperature is kept for 2h, and the mixture is naturally cooled to room temperature after complete reaction.

4. Etching process;

etching the silicon dioxide template in 2 mol/L sodium hydroxide solution by the mixture naturally cooled to room temperature to obtain the three-dimensional ordered porous carbon limited Co₉S₈Composite of quantum dots, denoted sample 1^#。

5. Preparing a sodium ion battery;

grinding active material powder, a conductive agent (Super P) and a binder (sodium carboxymethyl cellulose (CMC)) uniformly according to a 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 machine, and then preserving heat for 24 hours in a vacuum drying oven at 100 ℃. And cutting the dried electrode slice into electrode slices with the diameter of 12mm by using a slicing machine, and finally assembling the electrode slices into a sodium ion button cell in a glove box by using metal sodium as a counter electrode, wherein the sodium ion button cell is marked as a cell C1.

Example 2

1. Preparing a template;

2. Preparing a precursor;

3. A calcination process;

0.1g of cobalt oleate, 500mg of silica template spheres, 1g of thiourea and 2.5ml of oleylamine are uniformly mixed for 1h, finally, the obtained viscous mixture is placed in a tubular furnace in argon atmosphere, the temperature is raised to 750 ℃ at the heating rate of 7 ℃/min, the temperature is kept for 2h, the mixture is naturally cooled to room temperature after complete reaction, and the reaction result is recorded as a sample 2^#。

4. Etching process;

etching the silicon dioxide template in 2 mol/L sodium hydroxide solution by the mixture naturally cooled to room temperature to obtain the three-dimensional ordered porous carbon limited Co₉S₈A composite of quantum dots.

5. Preparing a sodium ion battery;

grinding active material powder, a conductive agent (Super P) and a binder (sodium carboxymethyl cellulose (CMC)) uniformly according to a mass ratio of 10:1.5:1, 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 in a vacuum drying oven at 100 ℃. And cutting the dried electrode slice into electrode slices with the diameter of 12mm by using a slicing machine, and finally assembling the electrode slices into a sodium ion button cell in a glove box by using metal sodium as a counter electrode, wherein the sodium ion button cell is marked as a cell C2.

Example 3

1. Preparing a template;

adding 2ml of ammonia water into a mixed solution of 30ml of ethanol and 3ml of deionized water, stirring for 30min at the temperature of 30 ℃, then adding 1ml of tetraethyl orthosilicate, continuously stirring for 6h at the temperature of 30 ℃, and then centrifugally drying to obtain SiO₂And (4) template balls.

2. Preparing a precursor;

3. A calcination process;

0.1g of cobalt oleate, 500mg of silica template spheres, 1g of thiourea and 2.5ml of oleylamine are uniformly mixed for 1 hour, finally, the obtained viscous mixture is placed in a tubular furnace in argon atmosphere, the temperature is raised to 700 ℃ at the heating rate of 7 ℃/min, the temperature is kept for 2 hours, the mixture is naturally cooled to room temperature after complete reaction, and the reaction result is marked as a sample 3^#。

4. Etching process;

5. Preparing a sodium ion battery;

grinding active material powder, a conductive agent (Super P) and a binder (sodium carboxymethyl cellulose (CMC)) uniformly according to a mass ratio of 10:1.5:1, 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 in a vacuum drying oven at 100 ℃. And cutting the dried electrode slice into electrode slices with the diameter of 12mm by using a slicing machine, and finally assembling the electrode slices into a sodium ion button cell in a glove box by using metal sodium as a counter electrode, wherein the sodium ion button cell is marked as a cell C3.

Example 4

1. Preparing a template;

in a mixed solution of 40ml of ethanol and 8ml of deionized waterAdding 5ml ammonia water, stirring at 25 deg.C for 30min, adding 4ml tetraethyl orthosilicate, stirring at 25 deg.C for 6h, and centrifuging and drying to obtain SiO₂And (4) template balls.

2. Preparing a precursor;

3. A calcination process;

0.1g of cobalt oleate, 500mg of silica template spheres, 1g of thiourea and 2.5ml of oleylamine are uniformly mixed for 1h, finally, the obtained viscous mixture is placed in a tubular furnace in argon atmosphere, the temperature is raised to 700 ℃ at the heating rate of 7 ℃/min, the temperature is kept for 2h, the mixture is naturally cooled to room temperature after complete reaction, and the reaction result is marked as sample 4^#。

4. Etching process;

5. Preparing a sodium ion battery;

grinding active material powder, a conductive agent (Super P) and a binder (sodium carboxymethyl cellulose (CMC)) uniformly according to a mass ratio of 10:1.5:1, 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 in a vacuum drying oven at 100 ℃. And cutting the dried electrode slice into electrode slices with the diameter of 12mm by using a slicing machine, and finally assembling the electrode slices into a sodium ion button cell in a glove box by using metal sodium as a counter electrode, wherein the sodium ion button cell is marked as a cell C4.

Example 5

1. Preparing a template;

adding 3ml ammonia water into a mixed solution of 35ml ethanol and 5ml deionized water, stirring for 30min at 35 ℃, then adding 3ml tetraethyl orthosilicate, continuously stirring for 6h at 35 ℃, and then centrifugally drying to obtain SiO₂And (4) template balls.

2. Preparing a precursor;

3. A calcination process;

0.1g of cobalt oleate, 500mg of silica template spheres, 1g of thiourea and 2.5ml of oleylamine are uniformly mixed for 1h, finally, the obtained viscous mixture is placed in a tubular furnace in argon atmosphere, the temperature is raised to 800 ℃ at the heating rate of 10 ℃/min, the temperature is kept for 2h, the mixture is naturally cooled to room temperature after complete reaction, and the reaction result is marked as sample 5^#。

4. Etching process;

5. Preparing a sodium ion battery;

grinding active material powder, a conductive agent (Super P) and a binder (sodium carboxymethyl cellulose (CMC)) uniformly according to a mass ratio of 10:1.5:1, 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 in a vacuum drying oven at 100 ℃. And cutting the dried electrode slice into electrode slices with the diameter of 12mm by using a slicing machine, and finally assembling the electrode slices into a sodium ion button cell in a glove box by using metal sodium as a counter electrode, wherein the sodium ion button cell is marked as a cell C5.

Example 6 sample 1^#～5^#Structural characterization of

For sample 1 respectively^#～5^#X-ray diffraction analysis was carried out, and the results showed that sample 1^#～5^#On the XRD spectrum of (1), the position of each diffraction peak and Co₉S₈The data in JCPDS (Joint Committee for powder diffraction standards) card (65-1765) of (A).

With sample 1^#The XRD spectrum and the comparison with the standard spectrum are shown in figure 1 as typical representations. Sample 2^#～5^#XRD spectrum of (1) and sample^#Similarly, the peak positions were the same, and the peak intensities varied within a range of. + -. 5% depending on the production conditions.

Example 7 sample 1^#～5^#Scanning electron microscopy and transmission electron microscopy analysis of

For sample 1 respectively^#～5^#Scanning electron microscopy and transmission electron microscopy were performed.

The results show that: quantum dot size Co₉S₈The carbon layer is limited and a three-dimensional ordered porous structure is constructed, the three-dimensional porous structure is formed, and the sample is spherical with the particle size of 100-300 nm.

With sample 1^#As a typical representative, the field emission scanning electron microscope is shown in fig. 2. As can be seen from FIG. 2, the sample is a uniform sphere with a particle size of 100 to 300 nm.

With sample 1^#Typical representative of the compounds, the transmission electron micrograph is shown in FIG. 3. As can be seen from FIG. 3, Co₉S₈The quantum dots are confined in the carbon layer and uniformly distributed.

With sample 1^#For representative purposes, a high resolution transmission electron micrograph is shown in FIG. 4. As can be seen from FIG. 3, Co₉S₈The quantum dots are confined in the carbon layer and build up a three-dimensional ordered porous structure.

EXAMPLE 8 Battery C1^#～C5^#Electrochemical performance test of

For battery C1 respectively^#～C5^#The electrochemical cycle performance of the test method is tested, and the specific steps are as follows:

and performing constant-current charge and discharge tests at room temperature at current densities of 0.1A/g, 0.2A/g, 0.5A/g, 1A/g, 2A/g, 5A/g and 10A/g respectively until the charge and discharge cutoff voltage is 0.01-3.0V.

The results show that lithium ion batteries prepared by the cathode material of the application have Co due to the size of quantum dots₉S₈Confined in the carbon layer and constructed into a three-dimensional ordered porous structure, the three-dimensional porous structure not only improves Co₉S₈Is Co, and has excellent rate performance₉S₈In circulation ofThe volume expansion generated in the ring process provides an effective buffer space, and good circulation stability is obtained; in addition, the three-dimensional porous structure is favorable for the electrolyte to permeate into the electrode, greatly reduces the diffusion path of sodium ions, and can be used with more Co₉S₈The contact of the active materials provides guarantee for high specific capacity, thereby greatly improving the electrochemical performance of the active materials as the negative electrode materials of the sodium-ion batteries.

With battery C1^#The test data are shown in fig. 5 and 6 as typical examples. As can be seen from FIG. 5, the battery capacity remained unchanged at 500mA h/g after 200 cycles at a current density of 0.1A/g. As can be seen from FIG. 6, through increasing multiplying power tests, when the current density returns to 0.1A/g, high capacity can be obtained, and the capacity value reaches about 500mA h/g, which shows that the Co is well improved by the unique structure₉S₈The conductivity of the electrolyte and the volume effect generated by the circulation process are problems, so that excellent electrochemical performance is obtained.

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

Claims

1. The battery cathode material is characterized in that the material is three-dimensional ordered porous carbon-limited Co₉S₈A composite of quantum dots;

wherein, Co₉S₈The quantum dots are confined in the carbon layer, forming a three-dimensional ordered porous structure.

2. The method for preparing the battery anode material according to claim 1, wherein the method comprises the steps of:

1) obtaining SiO₂A template ball;

2) obtaining a precursor cobalt oleate;

3. The method of claim 2, wherein the SiO is₂The template sphere was prepared by the following method:

adding ammonia water and tetraethyl orthosilicate into a mixed solution of ethanol and water, stirring, separating and drying to obtain SiO₂And (4) template balls.

4. The method according to claim 2, wherein the precursor cobalt oleate is prepared by a method comprising:

dissolving cobalt chloride and sodium oleate in a solution of ethanol, water and hexane, and refluxing for 3-5 h.

5. The method according to claim 2, wherein in the step 3), SiO is used₂The template ball comprises a precursor cobalt oleate, thiourea and oleylamine according to the mass ratio of (0.3-0.7): (0.1-0.5): 1: (1.2-2).

6. The preparation method according to claim 2, wherein the calcination process in the step 3) is: heating to 700-800 ℃ at a heating rate of 3-10 ℃/min, and then preserving the heat for 1.5-3 h.

7. The method according to claim 2, wherein the etching is performed in a NaOH solution having a concentration of 1.2 to 2.5 mol/L.

8. A sodium ion battery, characterized in that the negative electrode material of the sodium ion battery is the battery negative electrode material according to claim 1 or the negative electrode material prepared using the method of any one of claims 2 to 7.

9. The method of claim 8, wherein the method comprises:

10. The method for preparing the sodium-ion battery according to claim 9, wherein the mass ratio of the battery negative electrode material to the conductive agent and the binder is (6-10): (0.5-1.5): 1.