Disclosure of Invention
The invention aims to provide a preparation method of a metal sulfide doped hard carbon composite material capable of improving specific capacity and power performance of hard carbon.
The invention relates to a preparation method of a metal sulfide doped hard carbon composite material, which comprises the following steps:
step S1: hydrocarbon according to the mass ratio: nitrogen source = 100:1-5, adding hydrocarbon and nitrogen sources into deionized water, performing hydrothermal reaction (the temperature is 100-200 ℃, the pressure is 1-5Mpa, the reaction is 1-6 h), filtering, and vacuum drying filter residues at 80 ℃ for 24h to obtain a hard carbon precursor material;
step S2: hard carbon precursor according to mass ratio: metal sulfide: pitch = 100:1-5:1-5, uniformly mixing a hard carbon precursor, metal sulfide and asphalt, adding into a ball mill, ball milling for 24 hours at the rotating speed of 100r/min, and heating the obtained material to 200-300 ℃ for carbonization for 1-6 hours to obtain a sulfide amorphous carbon doped hard carbon composite material precursor;
step S3: transferring the precursor of the sulfide amorphous carbon-doped hard carbon composite material into a tube furnace, firstly heating to 200-300 ℃, introducing oxygen (the flow is 100 ml/min) for pre-carbonization for 1-6h, then stopping introducing oxygen, heating to 800-1400 ℃ for carbonization for 1-6h, and obtaining the metal sulfide doped hard carbon composite material.
In the preparation method of the metal sulfide doped hard carbon composite material, the hydrocarbon in the step S1 is one of naphthalene, phenanthrene or pyrene, and the nitrogen source is one of dopamine, melamine or urea.
The preparation method of the metal sulfide doped hard carbon composite material comprises the step S1, wherein the metal sulfide is one of molybdenum sulfide, tin sulfide or iron sulfide.
Compared with the prior art, the invention has obvious beneficial effects, and the technical scheme can be adopted as follows: according to the invention, the uniformity is improved by mixing the hard carbon precursor with the metal sulfide liquid phase, and the specific capacity and the power performance of the material are improved by virtue of the characteristics of high specific capacity and high electronic conductivity of the metal sulfide; meanwhile, amorphous carbon obtained by carbonization of doped asphalt is coated on the surface of the material, so that the defect of the material is reduced, and the first efficiency of the material is improved. Meanwhile, abundant groups are generated on the surface of the material by pre-oxidizing the material at the temperature of 200-300 ℃, so that the sodium storage performance of the material is improved, the surface defects of the material are reduced, the structural stability of the material is improved, the cycle performance is improved, and the first efficiency is improved after high-temperature carbonization.
Detailed Description
Example 1
A preparation method of a metal sulfide doped hard carbon composite material comprises the following steps:
step S1: adding 100g of naphthalene and 3g of dopamine into 500g of deionized water to prepare a solution, performing hydrothermal reaction at a temperature of 150 ℃ and a pressure of 3Mpa for 3 hours, filtering, and vacuum drying filter residues at 80 ℃ for 24 hours to obtain a hard carbon precursor material;
step S2: uniformly mixing 100g of hard carbon precursor, 3g of molybdenum sulfide and 3g of asphalt, adding into a ball mill, ball milling for 24 hours at the rotating speed of 100r/min, and heating the obtained material to 250 ℃ for carbonization for 3 hours to obtain a molybdenum sulfide amorphous carbon doped hard carbon composite material precursor;
step S3: transferring the molybdenum sulfide amorphous carbon doped hard carbon composite material precursor into a tube furnace, firstly heating to 250 ℃, introducing oxygen (the flow is 100 ml/min) for pre-carbonization for 3 hours, then stopping introducing oxygen, heating to 1100 ℃ for carbonization for 3 hours, and obtaining the metal sulfide amorphous carbon coated hard carbon composite material.
Example 2
A preparation method of a metal sulfide doped hard carbon composite material comprises the following steps:
step S1: adding 100g of phenanthrene and 1g of melamine into 500g of deionized water, uniformly dispersing, performing hydrothermal reaction at a temperature of 150 ℃ and a pressure of 3Mpa for 3 hours, filtering, and vacuum drying filter residues at 80 ℃ for 24 hours to obtain a hard carbon precursor material;
step S2: uniformly mixing 100g of hard carbon precursor material, 1g of tin sulfide and 1g of asphalt, adding into a ball mill, ball milling for 24 hours at the rotating speed of 100r/min, and heating the obtained material to 200 ℃ for carbonization for 6 hours to obtain a tin sulfide amorphous carbon doped hard carbon composite material precursor;
step S3: transferring the precursor of the tin sulfide amorphous carbon doped hard carbon composite material into a tube furnace, firstly heating to 200 ℃, introducing oxygen (the flow is 100 ml/min) for pre-carbonization for 6 hours, then stopping introducing oxygen, heating to 800 ℃ for carbonization for 6 hours, and obtaining the metal sulfide doped hard carbon composite material.
Example 3
A preparation method of a metal sulfide doped hard carbon composite material comprises the following steps:
step S1: adding 100g of pyrene and 5g of urea into 500g of deionized water, uniformly dispersing, performing hydrothermal reaction at 150 ℃ and 3Mpa under pressure for 3 hours, filtering, and vacuum drying filter residues at 80 ℃ for 24 hours to obtain a hard carbon precursor material;
step S2: uniformly mixing 100g of hard carbon precursor, 5g of ferric sulfide and 5g of asphalt, adding into a ball mill, ball milling for 24 hours at the rotating speed of 100r/min, and heating the obtained material to 300 ℃ for carbonization for 1 hour to obtain an amorphous carbon-doped hard carbon composite precursor of ferric sulfide;
step S3: transferring the precursor of the amorphous carbon-doped hard carbon composite material of the ferric sulfide into a tube furnace, heating to 300 ℃ at first under the inert atmosphere of argon, introducing oxygen (the flow is 100 ml/min) for pre-carbonization for 1h, stopping introducing oxygen, heating to 1400 ℃ for carbonization for 1h, and obtaining the amorphous carbon-coated hard carbon composite material of the metal sulfide.
Comparative example 1:
a preparation method of a metal sulfide doped hard carbon composite material comprises the following steps:
except for the difference from example 1, molybdenum sulfide and asphalt were not added, and the other was the same as in example 1.
Comparative example 2:
a preparation method of a metal sulfide amorphous carbon coated hard carbon composite material comprises the following steps:
unlike example 1, the pre-oxidation treatment was not performed. The detailed preparation process comprises the following steps: and (3) transferring the precursor of the molybdenum sulfide amorphous carbon doped hard carbon composite material in the step S1 in the material example 1 into a tube furnace, heating to 1100 ℃ and carbonizing for 3 hours to obtain the metal sulfide amorphous carbon coated hard carbon composite material.
Test example:
(1) SEM test
SEM testing was performed on the metal sulfide doped hard carbon composite material prepared in example 1, and the test results are shown in fig. 1. As can be seen from FIG. 1, the hard carbon composite material prepared in example 1 has a spherical structure, and the particle diameter D50 thereof is between (5-10) μm.
(2) Physical and chemical properties and button cell testing
Physical and chemical property test:
the metal sulfide doped hard carbon composite materials prepared in examples 1 to 3 and comparative examples 1 to 2 were subjected to measurement of interlayer spacing (D002), specific surface area, tap density, particle size D50, and powder conductivity. The testing method is tested according to the method of the national standard GBT-24533-2019 lithium ion battery graphite anode material. The test results are shown in Table 1.
Button cell test:
the metal sulfide doped hard carbon composite materials in the examples 1-3 and the comparative examples 1-2 are used as anode materials of lithium ion batteries to be assembled into button batteries, and the anode materials are specifically prepared by the following steps: according to the hard carbon composite material: CMC: SBR: SP: h2 Mixing the materials according to the mass ratio of O of 94:2.5:1.5:2:150 to prepare a negative plate; sodium flakes as counter electrode; the electrolyte adopts NaPF6 (the solvent is EC: DEC: PC: propylene glycol polyoxypropylene ether=1:2:1:0.05, the concentration is 1.3 mol/L) is electrolyte; the diaphragm adopts a composite film of polyethylene PE, polypropylene PP and polyethylene propylene PEP. The button cell assembly was performed in an argon filled glove box. Electrochemical performance was carried out on a Wuhan blue electric CT2001A type battery tester, the charging and discharging voltage range was 0.00V to 2.0V, the charging and discharging rate was 0.1C, and the first discharge specific capacity and first efficiency (1C/0.1C) of the button cell were tested. The test results are shown in Table 1.
TABLE 1
As can be seen from table 1, the metal sulfide doped hard carbon composite material prepared in the example is superior to the comparative example in specific capacity, first efficiency and powder conductivity, because the hard carbon precursor is doped with the metal sulfide, and the specific capacity and power performance of the material are improved by virtue of the high specific capacity and high electronic conductivity of the metal sulfide; meanwhile, amorphous carbon obtained by carbonization of doped asphalt is coated on the surface of the material, so that the defect of the material is reduced, and the first efficiency of the material is improved.
(3) Soft package battery test:
the metal sulfide doped hard carbon composite materials in examples 1-3 and comparative examples 1-2 were subjected to slurry mixing and coating to prepare a negative electrode sheet, and the negative electrode sheet was prepared as a layered oxide (NaFe)1/3 Mn1/3 Ni1/3 O2 ) As positive electrode, naPF6 (the solvent is EC: DEC: PC: propylene glycol polyoxypropylene ether=1:2:1:0.05 and 1.3 mol/L) as electrolyte to prepare the 5Ah soft package battery.
Testing the cycle performance: the charge and discharge current is 1.0C/1.0C, the voltage range is 1-4.0V, and the cycle number is 500.
Testing rate performance: the constant current ratio of the pouch battery under 2C charging conditions was tested, wherein the constant current ratio=constant current capacity/(2C constant current capacity+0.1C constant voltage capacity.
The test results are shown in Table 2.
TABLE 2
| Project | Cycle retention (%) | 2C constant current ratio (%) |
| Example 1 | 87.3 | 92.4 |
| Example 2 | 85.6 | 92.1 |
| Example 3 | 90.9 | 93.4 |
| Comparative example 1 | 89.3 | 87.6 |
| Comparative example 2 | 86.9 | 88.3 |
As can be seen from table 2, the negative electrode materials in examples 1 to 3 are significantly superior to the comparative examples in both rate and cycle performance, because of the analysis: the material of the embodiment has large interlayer spacing and powder conductivity, and improves the multiplying power performance of the material; meanwhile, the material of the embodiment has high specific surface area, so that the liquid retention performance of the material is improved, and the cycle performance is improved.
The foregoing description is only illustrative of the preferred embodiments of the present invention, and it is not to be construed as limiting the scope of the invention, for the equivalent variations of the claims are intended to be covered thereby.