Mesoporous hard carbon coated fe3c@si o2 composite material preparation method and application thereof

Abstract

The present application relates to a kind of mesoporous hard carbon coated Fe3C@SiO2 Composite material preparation method and its application. With ferrous oxalate as raw material, precursor is obtained by using sol-gel method and hydrothermal method combined method, and mesoporous hard carbon coated Fe3C@SiO2 Composite material is obtained by calcining under inert gas protection.The mesoporous hard carbon coated Fe3C@SiO2 Composite material of the present application is applied to the negative electrode material of sodium ion battery and potassium ion battery, and has good electrochemical performance, provides good foundation for the future development of sodium ion battery and potassium ion battery.

Description

Technical Field

[0001] This invention relates to novel energy materials, specifically to a method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material with good electrochemical performance, belonging to the technical field of sodium-ion battery anode materials. Background Technology

[0002] Lithium-ion batteries (LIBs) have become commercially successful energy storage devices due to their high energy density, high voltage, and long lifespan, powering most portable electronic devices. Graphite is currently the most commonly used commercial anode material because of its high conductivity, good cycleability, and abundant production. However, graphite's relatively low theoretical specific capacity and poor rate performance limit its application in high-performance batteries.

[0003] Non-graphite carbon materials exhibit much higher reversible capacity than graphite because they have an isotropic structure and a relatively large number of lithium-ion insertion sites on the electrode surface. Iron carbide (Fe3C) has advantages such as high hardness, magnetism, thermal stability, and resistance to oxidation processes.

[0004] The preparation of Fe3C usually requires high reaction temperatures, the use of hazardous chemicals, or complicated preparation processes. Summary of the Invention

[0005] This invention provides a method for preparing Fe3C@SiO2 composite material coated with mesoporous hard carbon and its application, solving the problems of high temperature requirements and cumbersome process in preparing Fe3C electrode materials.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The method for preparing the mesoporous hard carbon-coated Fe3C@SiO2 composite material of the present invention comprises the following steps:

[0008] (1) Weigh a certain amount of sodium nitrate and dissolve it in deionized water, then add a certain amount of ferrous oxalate and mix and stir.

[0009] (2) At a certain temperature, ethanol, nitric acid and tetraethyl orthosilicate (TEOS) are added to deionized water in sequence and mixed, and stirred for 30 min;

[0010] (3) Using a certain amount of chitin as a carbon source, dissolve it in concentrated acetic acid and add it to the mixture in step (2) and stir for a certain time;

[0011] (4) At a certain temperature, add the solution in (1) dropwise into (3) and stir for a certain time;

[0012] (5) Transfer the solution from step (4) to a hydrothermal reactor and keep it at a certain hydrothermal temperature for a certain time;

[0013] (6) The mixture in step (5) was washed twice with ethanol and three times with deionized water. The resulting mixture had a neutral pH.

[0014] (7) The mixture from step (6) is dried in an oven at 70°C and then ground into powder to obtain the precursor;

[0015] (8) The precursor obtained in step (7) is kept at low temperature for a certain time under the protection of inert gas or nitrogen, and then heated to high temperature for a certain time. After being kept at high temperature, it is naturally cooled to room temperature to obtain mesoporous hard carbon coated Fe3C@SiO2 composite material.

[0016] According to the method for preparing a mesoporous hard carbon coated Fe3C@SiO2 composite material, the molar ratio of deionized water, ethanol, nitric acid and tetraethyl orthosilicate (TEOS) added in step (2) is 3:1:1:1, and the temperature is 40℃~60℃.

[0017] According to the method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material, the addition ratio of ferrous oxalate and tetraethyl orthosilicate (TEOS) in steps (1) and (2) is any molar ratio between 0.01 and 0.99.

[0018] The method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material is characterized in that the time in step (3) is 1~2h.

[0019] According to the method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material, the carbon source in step (3) is chitin, and the amount is 0.5~3% by mass.

[0020] According to the method for preparing a mesoporous hard carbon coated Fe3C@SiO2 composite material, the temperature of the drop-addition process in step (4) is 55℃~70℃.

[0021] According to the method for preparing a mesoporous hard carbon coated Fe3C@SiO2 composite material, the hydrothermal temperature in step (5) is 90℃~120℃ and the hydrothermal time is 12h~72h.

[0022] According to the method for preparing a mesoporous hard carbon coated Fe3C@SiO2 composite material, the low temperature treatment temperature described in step (8) is 200-400℃ and the holding time is 4h-6h; the high temperature treatment temperature is 500-700℃ and the holding time is 5h-8h.

[0023] According to the method for preparing a mesoporous hard carbon coated Fe3C@SiO2 composite material, in step (8), the inert gas is one or more of helium and argon.

[0024] According to the application of the method for preparing a mesoporous hard carbon coated Fe3C@SiO2 composite material, the Fe3C@SiO2 composite material obtained in step (8) is used as a negative electrode material for sodium-ion batteries and potassium-ion batteries. The application method is as follows: (1) After thoroughly grinding and mixing nitrogen-doped mesoporous hard carbon Fe3C@SiO2 with conductive agent and binder, N-methylpyrrolidone solvent is added and stirred evenly to obtain a pre-coated refined slurry; (2) The above pre-coated refined slurry is coated on copper foil, and then the electrode sheet is dried to obtain a negative electrode sheet for sodium-ion batteries or potassium-ion batteries. The obtained negative electrode sheet is used for button-type sodium-ion batteries or potassium-ion batteries.

[0025] The beneficial effects of this invention are as follows: The mesoporous hard-coated carbon Fe3C@SiO2 composite anode material for sodium-ion batteries prepared by the method of this invention has an initial discharge specific capacity of 1256.6 mAh g at a charge / discharge voltage of 0.01~3.0V and a current of 0.2C. -1 After 1000 cycles at 1C, the charge-discharge efficiency reaches 99%. This invention uses ferrous oxalate as the iron source and combines the sol-gel method and the hydrothermal method to synthesize a mesoporous hard carbon-coated Fe3C@SiO2 composite material through calcination. This method has mild reaction conditions, simple process, convenient operation, and low production cost, and has great development potential for large-scale production. Attached Figure Description

[0026] Figure 1 This is the XRD pattern of Example 2.

[0027] Figure 2 This is a battery cycle performance diagram for Example 2. Detailed Implementation

[0028] The present invention will be further described below:

[0029] The preparation method of the mesoporous hard carbon-coated Fe3C@SiO2 composite material of the present invention includes the following steps:

[0030] (1) Weigh a certain amount of sodium nitrate and dissolve it in deionized water, then add a certain amount of ferrous oxalate and mix and stir.

[0031] (2) At 40℃~60℃, ethanol, nitric acid and tetraethyl orthosilicate (TEOS) are added to deionized water in sequence and mixed. The mixture is stirred for 30 min. The molar ratio of deionized water, ethanol, nitric acid and tetraethyl orthosilicate (TEOS) is 3:1:1:1, and the addition ratio of ferrous oxalate and tetraethyl orthosilicate (TEOS) is any molar ratio between 0.01 and 0.99.

[0032] (3) Using chitin with a mass concentration of 0.5~3% as a carbon source, dissolve it in concentrated acetic acid, and then add it to the mixture in step (2) and stir for a certain period of time;

[0033] (4) At a certain temperature, the solution in (1) is added dropwise to (3). The temperature during the dropwise addition process is 55℃~70℃, and the mixture is stirred for a certain time.

[0034] (5) Transfer the solution from step (4) to a hydrothermal reactor. The hydrothermal temperature is 90℃~120℃ and the hydrothermal time is 12h~72h.

[0035] (6) The mixture in step (5) was washed twice with ethanol and three times with deionized water. The resulting mixture had a neutral pH.

[0036] (7) The mixture from step (6) is dried in an oven at 70°C and then ground into powder to obtain the precursor;

[0037] (8) The precursor obtained in step (7) is kept at 200-400℃ for 4-6 hours under inert gas or nitrogen protection, then heated to 500-700℃ for high temperature treatment, kept at 5-8 hours, and then naturally cooled to room temperature to obtain mesoporous hard carbon coated Fe3C@SiO2 composite material.

[0038] (9) The mesoporous hard carbon-coated Fe3C@SiO2 composite material obtained in step (8) is used as the negative electrode material for sodium-ion batteries and potassium-ion batteries. The application method is as follows:

[0039] 1) After thoroughly grinding and mixing nitrogen-doped mesoporous hard carbon Fe3C@SiO2 with conductive agent and binder, N-methylpyrrolidone solvent is added and stirred evenly to obtain a pre-coated refined slurry; 2) The above pre-coated refined slurry is coated on copper foil, and then the electrode sheet is dried to obtain a sodium-ion battery or potassium-ion battery negative electrode sheet. The obtained negative electrode sheet is used for button-type sodium-ion batteries or potassium-ion batteries.

[0040] To further implement this invention, the following description, in conjunction with embodiments, will further illustrate the invention, but it is not limited thereto.

[0041] Example 1

[0042] (1) Weigh a certain amount of 0.01 mol sodium nitrate and dissolve it in deionized water, then add 0.01 mol ferrous oxalate and mix.

[0043] (2) At 55°C, add 0.01 mol of tetraethyl orthosilicate (TEOS), wherein deionized water, ethanol, nitric acid and tetraethyl orthosilicate (TEOS) are added in a molar ratio of 3:1:1:1 and then mixed and stirred for 30 min.

[0044] (3) Add chitin with a mass concentration of 1% as a carbon source, dissolve it in concentrated acetic acid, and then add it to step (2) and mix and stir for 1.5h.

[0045] (4) At 55℃, add the solution in (1) dropwise into (3) and stir for a certain period of time.

[0046] (5) Transfer the solution from step (4) to a hydrothermal reactor and keep it at 100°C for 12 hours.

[0047] (6) Wash the mixture in step (5) twice with ethanol and three times with deionized water, with a pH value of neutral.

[0048] (7) The mixture from step (6) is dried in an oven at 70°C and then ground into powder to obtain the precursor.

[0049] (8) The precursor obtained in step (7) is kept at 300°C for 4 hours under nitrogen protection, and then the temperature is increased to 650°C for 7 hours. After that, it is naturally cooled to room temperature to obtain the mesoporous hard carbon coated Fe3C@SiO2 composite material.

[0050] (9) After the nitrogen-doped mesoporous hard carbon Fe3C@SiO2 is thoroughly ground and mixed with the conductive agent and binder, N-methylpyrrolidone solvent is added and stirred evenly to obtain a pre-coated refined slurry; (10) The above pre-coated refined slurry is coated on copper foil, and then the electrode sheet is dried to obtain a sodium-ion battery or potassium-ion battery negative electrode sheet. The obtained negative electrode sheet is used for button-type sodium-ion batteries.

[0051] Example 2

[0052] (1) Weigh a certain amount of 0.01 mol and dissolve it in deionized water, then add 0.01 mol of ferrous oxalate and mix.

[0053] (2) At 45°C, add 0.005 mol of tetraethyl orthosilicate (TEOS), wherein deionized water, ethanol, nitric acid and tetraethyl orthosilicate (TEOS) are added in a molar ratio of 3:1:1:1 and then mixed and stirred for 30 min.

[0054] (3) Add chitin with a mass concentration of 1.5% as a carbon source, dissolve it in concentrated acetic acid, and then add it to step (2) and mix and stir for 1.5h.

[0055] (4) At 50℃, add the solution in (1) dropwise into (3) and stir for a certain period of time.

[0056] (5) Transfer the solution from step (4) to a hydrothermal reactor and keep it at 110°C for 8 hours.

[0057] (6) Wash the mixture in step (5) twice with ethanol and three times with deionized water, with a pH value of neutral.

[0058] (7) The mixture from step (6) is dried in an oven at 70°C and then ground into powder to obtain the precursor.

[0059] (8) The precursor obtained in step (7) is kept at 300°C for 4 hours under nitrogen protection, and then the temperature is increased to 650°C for 7 hours. After that, it is naturally cooled to room temperature to obtain the mesoporous hard carbon coated Fe3C@SiO2 composite material.

[0060] (9) After the nitrogen-doped mesoporous hard carbon Fe3C@SiO2 is thoroughly ground and mixed with the conductive agent and binder, N-methylpyrrolidone solvent is added and stirred evenly to obtain a pre-coated refined slurry; (10) The above pre-coated refined slurry is coated on copper foil, and then the electrode sheet is dried to obtain a sodium-ion battery or potassium-ion battery negative electrode sheet. The obtained negative electrode sheet is used for button-type sodium-ion batteries.

[0061] The mesoporous hard-coated carbon Fe3C@SiO2 composite anode material for sodium-ion batteries prepared by the method of this invention exhibits an initial discharge specific capacity of 1256.6 mAh g at charge / discharge voltages of 0.01–3.0 V and a current of 0.2 C. -1 After 1000 cycles at 1C, the charge-discharge efficiency reaches 99%. This invention uses ferrous oxalate as the iron source and combines the sol-gel method and the hydrothermal method to synthesize a mesoporous hard carbon-coated Fe3C@SiO2 composite material through calcination. This method has mild reaction conditions, simple process, convenient operation, and low production cost, and has great development potential for large-scale production.

Claims

1. A method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material, characterized in that, The steps are as follows: (1) Weigh a certain amount of sodium nitrate and dissolve it in deionized water, then add a certain amount of ferrous oxalate and mix and stir. (2) At a certain temperature, ethanol, nitric acid and tetraethyl orthosilicate are added to deionized water in sequence and mixed, and stirred for 30 min; (3) Using a certain amount of chitin as a carbon source, dissolve it in concentrated acetic acid and add it to the mixture in step (2) and stir for a certain time; (4) At a certain temperature, add the solution in (1) dropwise into (3) and stir for a certain time; (5) Transfer the solution from step (4) to a hydrothermal reactor and keep it at a certain hydrothermal temperature for a certain time; (6) The mixture in step (5) was washed twice with ethanol and three times with deionized water. The resulting mixture had a neutral pH. (7) The mixture from step (6) is dried in an oven at 70°C and then ground into powder to obtain the precursor; (8) The precursor obtained in step (7) is kept at low temperature for a certain time under the protection of inert gas or nitrogen, and then heated to high temperature for a certain time. After being kept at high temperature, it is naturally cooled to room temperature to obtain mesoporous hard carbon coated Fe3C@SiO2 composite material. The low temperature treatment temperature is 200~400℃ and the holding time is 4h~6h. The high-temperature treatment temperature is 500~700℃, and the holding time is 5h~8h.

2. The method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material according to claim 1, characterized in that, The molar ratio of deionized water, ethanol, nitric acid and tetraethyl orthosilicate added in step (2) is 3:1:1:1, and the temperature is 40℃~60℃.

3. The method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material according to claim 1, characterized in that, In steps (1) and (2), the addition ratio of ferrous oxalate and tetraethyl orthosilicate is any molar ratio between 0.01 and 0.

99.

4. The method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material according to claim 1, characterized in that, The time in step (3) is 1 to 2 hours.

5. The method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material according to claim 1, characterized in that, The carbon source in step (3) is chitin, and a certain amount is 0.5-3% by mass.

6. The method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material according to claim 1, characterized in that, The temperature during the dripping process in step (4) is 55℃~70℃.

7. The method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material according to claim 1, characterized in that, In step (5), the hydrothermal temperature is 90℃~120℃ and the hydrothermal time is 12h~72h.

8. The method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material according to claim 1, characterized in that, Step (8) The inert gas is one or more of helium and argon.

9. An application of the method for preparing a mesoporous hard carbon-coated Fe3C@SiO2 composite material according to claim 1, characterized in that, The Fe3C@SiO2 composite material obtained in step (8) is used as the negative electrode material for sodium-ion batteries and potassium-ion batteries. The application method is as follows: (1) After thoroughly grinding and mixing nitrogen-doped mesoporous hard carbon Fe3C@SiO2 with conductive agent and binder, N-methylpyrrolidone solvent is added and stirred evenly to obtain a pre-coated refined slurry; (2) The above pre-coated refined slurry is coated on copper foil, and then the electrode sheet is dried to obtain the negative electrode sheet for sodium-ion batteries or potassium-ion batteries. The obtained negative electrode sheet is used for button-type sodium-ion batteries or potassium-ion batteries.

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