Porous carbon material, method for producing the same, and use thereof

Abstract

The application provides a preparation method of a porous carbon material, which prepares the porous carbon material with specific pore structure by adjusting the ratio of ammonium dihydrogen phosphate and F127 and the carbonization temperature, and when used as a negative electrode material of a sodium ion battery, the sodium ion battery can effectively balance the initial efficiency and capacity on the basis of improving the sodium storage capacity. Moreover, the preparation method of the porous carbon material is simple, low in cost and suitable for industrialization.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of carbon materials, in particular to a porous carbon material and a preparation method and use thereof. BACKGROUND

[0002] Benefiting from the global energy-saving and emission-reducing trend and the carbon emission agreement reached by the European Union, the global lithium battery market entered a period of rapid demand growth after 2018. However, lithium resources are scarce and unevenly distributed. In contrast, sodium-ion batteries have good cycle life and are comparable to various types of lithium-ion batteries in terms of rate performance, high and low temperature performance, and have resource advantages, and have good application prospects in the field of energy storage.

[0003] Asphalt is widely used in the field of battery negative electrodes due to its high carbon yield and low cost. However, due to its short-range order-long-range disorder mechanism, when used as a negative electrode material for sodium-ion batteries, it exhibits low capacity.

[0004] The preparation process in the prior art by pre-oxidation or adding hard carbon can effectively inhibit the graphitization of asphalt, but the cost is high. Further, in the prior art, a porous asphalt negative electrode material is prepared by a template method to increase the active sites of sodium ions and thus improve the sodium storage capacity. However, the porous structure introduced by the template method can reduce the initial coulombic efficiency, which cannot effectively balance the initial efficiency and capacity, and the process is complex and the raw material cost is high.

[0005] Therefore, there is still an urgent need in the art for a sodium-ion battery negative electrode material with high sodium storage capacity and balanced initial efficiency and capacity. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a preparation method of a porous carbon material. The method adjusts the ratio of ammonium dihydrogen phosphate (NH4H2PO4) to Pluronic F127, a triblock copolymer of polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO), and the carbonization temperature to prepare a porous carbon material with a specific pore structure. When used as a negative electrode material for sodium-ion batteries, it can effectively balance the initial efficiency and capacity on the basis of improving the sodium storage capacity. Moreover, the preparation method of the porous carbon material of the present application is simple, low in cost and suitable for industrialization.

[0007] To achieve the purpose of the present application, the following technical solutions are adopted:

[0008] In the first aspect of the present application, a preparation method of a porous carbon material is provided, comprising the following steps:

[0009] 1) F127, ammonium dihydrogen phosphate and asphalt are added to a solvent for mechanical mixing to obtain a uniform slurry;

[0010] 2) drying the mixed slurry in an oven, and then carbonizing the slurry in an argon environment at a carbonization temperature as follows:

[0011] carbonizing at 60℃ for 0.5-5h;

[0012] carbonizing at 250-350℃ for 0.5-5h;

[0013] carbonizing at 500-600℃ for 0.5-5h;

[0014] carbonizing at 600-1000℃ for 0.5-5h;

[0015] 3) cooling to obtain the porous carbon material.

[0016] The preparation method of the porous carbon material according to the present application, wherein in step 1),

[0017] the mass ratio of F127 to pitch is 0.125-0.5:1, the mass ratio of ammonium dihydrogen phosphate to pitch is 0.125-0.5:1, and the mass ratio of ammonium dihydrogen phosphate+F127 to pitch is 0.25-1:1;

[0018] the solvent is one or more of ethanol, isopropyl alcohol, acetone, and preferably ethanol;

[0019] the pitch is one or more of coal pitch and petroleum pitch;

[0020] the mechanical mixing includes ball milling, stirring or ultrasonic dispersion, and any combination of ball milling, stirring or ultrasonic dispersion.

[0021] The preparation method of the porous carbon material according to the present application, wherein in step 2),

[0022] each carbonization process includes a temperature rising process, wherein the temperature rising rate of the temperature rising process is 2℃ / min to 60℃, 2℃ / min to 250-350℃, 5℃ / min to 500-600℃, and 5℃ / min to 600-1000℃.

[0023] The preparation method of the porous carbon material according to the present application, wherein in step 3), the cooling is natural cooling to room temperature.

[0024] In the second aspect of the present application, the porous carbon material prepared according to the above preparation method is provided.

[0025] The porous carbon material according to the present application, wherein,

[0026] the porous carbon material is spherical and has a particle size of 5-10μm;

[0027] The porous carbon material has the following structural characteristics: the percentage of micropore pore volume of <2 nm to mesopore pore volume of 2-20 nm is greater than 5 and less than or equal to 6;

[0028] The porous carbon material is used for preparing a negative electrode of a sodium ion battery.

[0029] In a third aspect of the present application, use of the above-mentioned porous carbon material in the preparation of a sodium ion battery is provided.

[0030] In a fourth aspect of the present application, a sodium ion battery negative electrode material is provided, which comprises the above-mentioned porous carbon material.

[0031] In a fifth aspect of the present application, a preparation method of a sodium ion battery negative electrode material is provided, comprising the following steps:

[0032] The porous carbon material is prepared according to the above-mentioned preparation method of the porous carbon material, and the prepared porous carbon material is mixed with a conductive agent and a binder to obtain a sodium ion battery negative electrode material.

[0033] In a sixth aspect of the present application, a sodium ion battery is provided, which comprises the above-mentioned sodium ion battery negative electrode material.

[0034] Compared with the prior art, the present application has the following advantages:

[0035] In the prior art, the graphitization of pitch is inhibited by pre-oxidation or the addition of hard carbon, but the preparation process is relatively high in cost; in the prior art, a porous pitch negative electrode material is prepared by a template method, which is relatively complex in process and high in raw material cost. In comparison, the present application uses inexpensive and readily available ammonium dihydrogen phosphate, F127 and pitch as raw materials, and by adjusting the ratio of ammonium dihydrogen phosphate to F127 and adjusting the carbonization temperature, a porous carbon material with a specific pore structure is prepared, wherein the percentage of micropore pore volume of <2 nm to mesopore pore volume of 2-20 nm is greater than 5 and less than or equal to 6. Such a porous carbon material with a specific pore structure is conducive to the storage of sodium ions, thereby achieving high capacity; in the carbonization process, the carbonization temperature is adjusted, which is simple and convenient to operate and does not require furnace replacement and in-situ heating; when the porous carbon material of the present application is used as a sodium ion battery negative electrode material, the sodium storage capacity is improved, and the initial efficiency and capacity can be effectively balanced. It can be seen that the preparation method of the porous carbon material of the present application is simple, low in cost, and the obtained material has excellent sodium storage performance and effectively balances the initial efficiency and capacity, which is suitable for industrialization. DETAILED DESCRIPTION

[0036] The present application will be further described below in conjunction with examples, but the present application is not limited to the listed examples.

[0037] The raw material information used in the following examples / comparative examples is as follows:

[0038] Ammonium dihydrogen phosphate analytical pure Sigma-Aldrich

[0039] F127 analytical pure Sigma-Aldrich

[0040] Asphalt analytical pure Jining Keneng New Carbon Material Co., Ltd.

[0041] Example

[0042] Example 1 Preparation of porous carbon material

[0043] Preparation steps:

[0044] 1) F127, ammonium dihydrogen phosphate and petroleum asphalt were added to ethanol in a mass ratio of 5g:5g:10g, stirred for 2h to obtain a uniform slurry;

[0045] 2) The uniformly mixed slurry was dried in an oven, and then carbonization treatment was carried out in a tube furnace under argon protection according to the following carbonization temperature: 60°C carbonization for 1h, then 350°C carbonization for 1h, followed by 600°C carbonization for 2h, and finally 800°C carbonization for 2h;

[0046] 3) Cooling to obtain a porous carbon material.

[0047] Example 2 Preparation of porous carbon material

[0048] Preparation steps:

[0049] 1) F127, ammonium dihydrogen phosphate and petroleum asphalt were added to isopropanol in a mass ratio of 2.5g:2.5g:20g, stirred for 2h to obtain a uniform slurry;

[0050] 2) The uniformly mixed slurry was dried in an oven, and then carbonization treatment was carried out in a tube furnace under argon protection according to the following carbonization temperature: 60°C carbonization for 2h, then 350°C carbonization for 2h, followed by 600°C carbonization for 2h, and finally 900°C carbonization for 2h;

[0051] 3) Cooling to obtain a porous carbon material.

[0052] Example 3 Preparation of porous carbon material

[0053] Preparation steps:

[0054] 1) F127, ammonium dihydrogen phosphate and coal tar were added to ethanol in a mass ratio of 10g:2.5g:20g, stirred for 2h to obtain a uniform slurry;

[0055] 2) The uniformly mixed slurry was dried in an oven, and then carbonized in a tube furnace under argon protection according to the following carbonization temperature: 60°C for 2h, then 300°C for 3h, followed by 600°C for 2h, and finally 1000°C for 2h;

[0056] 3) Cooling to obtain the porous carbon material.

[0057] Example 4 Preparation of porous carbon material

[0058] Preparation steps:

[0059] 1) F127, ammonium dihydrogen phosphate and coal pitch were added to acetone in a mass ratio of 10g:2.5g:20g, stirred for 2h to obtain a uniform slurry;

[0060] 2) The uniformly mixed slurry was dried in an oven, and then carbonized in a tube furnace under argon protection according to the following carbonization temperature: 60°C for 2h, then 300°C for 5h, followed by 600°C for 2h, and finally 1000°C for 5h;

[0061] 3) Cooling to obtain the porous carbon material.

[0062] Comparative Examples 1-4

[0063] The porous carbon materials of Comparative Examples 1-4 were prepared according to the raw material amounts in Table 1 below using the same preparation method as Example 1.

[0064] Table 1

[0065] F127 amount Ammonium dihydrogen phosphate amount Asphalt amount Comparative Example 1 0 0 1 Comparative Example 2 0 1 2 Comparative Example 3 1 0 2 Comparative Example 4 1 0.125 2

[0066] Test Example

[0067] Electrochemical test

[0068] Test equipment:

[0069] Half-cell charge-discharge tests were performed on a blue CT2001 battery test system.

[0070] Test conditions:

[0071] Room temperature environment, cycle voltage range 0-2V, charge and discharge current 30mA / g.

[0072] Test steps:

[0073] The active material, conductive carbon black Super P, binder PVDF and solvent N-methyl pyrrolidine (NMP) were mixed uniformly in a mass ratio of 92:3:5, coated on a copper foil, dried at 100°C for 24h in vacuum, and punched into round electrode sheets with a diameter of about 13mm by a puncher. The electrode sheets were transferred into a glove box to assemble CR2032 button cells, with a metal sodium sheet as the counter electrode and auxiliary electrode, and an electrolyte of 1mol / L sodium hexafluorophosphate / (ethylene carbonate + diethyl carbonate) (NaPF6 / (EC+DEC) mixed solution with a volume ratio of 1:1), and a Celgard 2400PP membrane as the separator.

[0074] Specific surface area (BET) and pore structure test

[0075] Test equipment

[0076] BET and pore structure analysis were performed on a Micromeretics ASAP 2010 analyzer.

[0077] Test conditions

[0078] N2 was used as the adsorbate, and the adsorption was performed at liquid nitrogen temperature (77K), and the specific surface area was determined by the BET method, with a linear range of P / P0=0.05-0.3.

[0079] Wherein P0 is the saturated vapor pressure of the adsorbate at the experimental temperature, and P is the equilibrium pressure during adsorption.

[0080] After degassing at 300°C for 3h, the BET test was performed.

[0081] Test results

[0082] The test results are shown in Table 2 below.

[0083] Table 2

[0084]

[0085] The above test results show that the porous carbon material prepared according to the method of the present application has a specific pore structure, wherein the percentage of the pore volume of micropores <2nm to the pore volume of mesopores 2-20nm is greater than 5 and less than or equal to 6, and such a porous carbon material with a specific pore structure is beneficial to the storage of sodium ions, thereby achieving high capacity. Moreover, when used as a negative electrode material for sodium ion batteries, it can effectively balance the initial efficiency and capacity on the basis of improving the sodium storage capacity.

[0086] Although the present application has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that changes in the details can be made by those skilled in the art without departing from the spirit and scope of the present application which is defined by the following claims.

Claims

1. A method for preparing a porous carbon material, comprising the following steps: 1) adding F127, ammonium dihydrogen phosphate and pitch into a solvent to perform mechanical mixing to obtain a uniform slurry, wherein the mass ratio of F127 to pitch is 0.125-0.5:1, the mass ratio of ammonium dihydrogen phosphate to pitch is 0.125-0.5:1, and the mass ratio of ammonium dihydrogen phosphate+F127 to pitch is 0.25-1:1; 2) drying the uniformly mixed slurry in an oven, and then performing carbonization treatment in an argon environment according to the following carbonization temperature: carbonization treatment at 60℃ for 0.5-5h; carbonization treatment at 250-350℃ for 0.5-5h; carbonization treatment at 500-600℃ for 0.5-5h; carbonization treatment at 600-1000℃ for 0.5-5h; 3) cooling to obtain the porous carbon material. In step 1), the solvent is one or more of ethanol, isopropanol and acetone; the pitch is one or more of coal pitch and petroleum pitch; and the mechanical mixing comprises ball milling, stirring or ultrasonic dispersion, or a combination of any of the above.

2. The method according to claim 1, wherein in step 1), the solvent is ethanol.

3. The method according to any one of claims 1-2, wherein in step 2), each carbonization treatment includes a temperature rising process, wherein the temperature rising rate of the temperature rising process is 2℃ / min to 60℃, 2℃ / min to 250-350℃, 5℃ / min to 500-600℃, and 5℃ / min to 600-1000℃.

4. The method according to any one of claims 1-3, wherein in step 3), the cooling is natural cooling to room temperature.

5. The method according to any one of claims 1-4, wherein in step 2), the carbonization treatment at 250-350℃ is performed for 1-3h; the carbonization treatment at 500-600℃ is performed for 1-3h; and the carbonization treatment at 600-1000℃ is performed for 1-3h.

6. A porous carbon material prepared by the method according to any one of claims 1-5.

7. The porous carbon material according to claim 6, wherein the porous carbon material is spherical and has a particle size of 5-10μm; and the porous carbon material has the following structural characteristics: the percentage of micropore volume of <2nm to mesopore volume of 2-20nm is greater than 5 and less than or equal to 6.

8. Use of the porous carbon material prepared by the method according to any one of claims 1-5 or the porous carbon material according to claim 6 or 7 in the preparation of a sodium ion battery.

2. The method for producing a porous carbon material according to claim 1, wherein, 9. A sodium ion battery negative electrode material comprising the porous carbon material prepared by the method according to any one of claims 1-5 or the porous carbon material according to claim 6 or 7.

10. A method for preparing a sodium ion battery negative electrode material, comprising the following steps: mixing the porous carbon material prepared by the method according to any one of claims 1-5 or the porous carbon material according to claim 6 or 7 with a conductive agent and a binder to obtain the sodium ion battery negative electrode material.

11. A sodium ion battery comprising the sodium ion battery negative electrode material according to claim 9 or the sodium ion battery negative electrode material prepared by the method according to claim 10. ​ 3. The method for producing a porous carbon material according to claim 2, wherein, ​ 4. The method for producing the porous carbon material according to claim 1, wherein ​ ​ 5. The method for producing the porous carbon material according to claim 1, wherein, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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