CN113233440A - Modified preparation method of hard carbon negative electrode material with high first efficiency and long cycle life - Google Patents
Modified preparation method of hard carbon negative electrode material with high first efficiency and long cycle life Download PDFInfo
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- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
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Abstract
The invention provides a modified preparation method of a hard carbon negative electrode material with high first efficiency and excellent cycle life, which comprises the following steps: s1, premixing 10 parts of NMP and 10 parts of medium-temperature coal tar pitch; s2, placing 40 parts of biomass hard carbon into 30-60 parts of organic solution, stirring to prepare a suspension, adding 2.4-4.8 parts of carbon tube slurry into the suspension, and uniformly stirring; s3, adding the pre-mixed asphalt solution in the S1 into the mixture obtained in the S2, and uniformly stirring; and S4, heating and evaporating the mixture obtained in the step S3 to dryness, roasting and cooling the mixture in a CAD furnace under the protection of inert gas, and screening to obtain the modified hard carbon negative electrode material for the sodium ion battery. The modified hard carbon negative electrode material prepared by the invention has the advantages of high first-efficiency and excellent cycle life, and in addition, the preparation process is convenient to operate, low in cost and suitable for industrial production.
Description
Technical Field
The invention relates to the field of sodium ion batteries, in particular to a method for preparing a hard carbon negative electrode material with high first efficiency and long cycle life by modification.
Background
The sodium ion battery is a novel energy storage power supply, has the advantages of rich raw material reserves, wide distribution, low cost, no development bottleneck, environmental friendliness, compatibility with the existing production equipment of the lithium ion battery, better power characteristics, wide temperature range applicability, safety performance, no over-discharge problem and the like. Meanwhile, by means of the characteristic that the anode and the cathode can adopt aluminum foil current collectors to construct the bipolar battery, the energy density of the sodium ion battery can be further improved, and the sodium ion battery is enabled to move towards the directions of low cost, long service life, high specific energy and high safety. At present, the negative electrode material of the sodium ion battery mainly takes biomass hard carbon as a main material. However, the hard carbon roasted at low temperature has the defects of low first effect, low electronic conductivity and unstable circulation although the hard carbon has higher ionic conductivity; although the high-temperature roasted hard carbon has the advantages of high first efficiency, high electronic conductivity and relatively stable structure, the high-temperature roasted hard carbon has lower ionic conductivity and lower gram capacity, and the application of high-rate charge and discharge of the high-temperature roasted hard carbon is limited. Therefore, the development of coating modification of biomass hard carbon is imminent. How to improve the first effect, the electronic conductivity and the structural stability without reducing the ionic conductivity and the gram volume has become the focus of research in the industry.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a method for preparing a hard carbon negative electrode material with high first efficiency and long cycle life by modification.
In order to solve the technical problems, the invention adopts the technical scheme that: a method for preparing a hard carbon negative electrode material with high first efficiency and long cycle life by modification comprises the following steps:
s1, premixing 10 parts of NMP and 10 parts of medium-temperature coal tar pitch;
s2, placing 40 parts of biomass hard carbon into 30-60 parts of organic solution, stirring to prepare a suspension, adding 2.4-4.8 parts of carbon tube slurry into the suspension, and uniformly stirring;
s3, adding the pre-mixed asphalt solution in the S1 into the mixture obtained in the S2, and uniformly stirring;
and S4, heating and evaporating the mixture obtained in the step S3 to dryness, roasting and cooling the mixture in a CAD furnace under the protection of inert gas, and screening to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Further, in the carbon tube slurry in S2, the solid content of carbon tubes is 5%; and roasting the biomass hard carbon at the temperature of 1000-1300 ℃ before adding the biomass hard carbon into the stirrer.
Further, 8 to 16 parts of an asphalt solution is added to the S3, and the mixture obtained in S2 is stirred for 3 to 5 hours.
Further, in the roasting and cooling process of the mixture in the S4 under the protection of inert gas, the flow rate of the inert gas is 5-8L/min; after cooling, the mixture was screened to 300 mesh.
Further, the roasting temperature in the roasting process in the S4 is 1000 ℃, wherein the heating rate is 3-5 ℃/min.
Further, in the premixing process of the NMP and the medium temperature coal tar pitch in the S1, the NMP and the medium temperature coal tar pitch are added into a double-planet stirrer, the revolution speed is set to be 40r/min, the rotation speed is set to be 2500r/min, and the stirring time is 5 hours.
Further, in the process of preparing the suspension in S2, the stirring speed is 160-200r/min, and the stirring time is 2-4 h.
Further, in the step of heating and evaporating to dryness in S4, the heating temperature is 90-120 ℃, the heating time is 16-24h, the stirring state is kept in the heating process, and the rotating speed is 160-200 r/min.
Further, before roasting in the S4, inert gas is introduced for 1h for evacuation, and in the roasting process, the temperature is raised to 1000 ℃ and is kept for 2-4h, and then the mixture is naturally cooled under the protection of the inert gas.
Compared with the prior art, the invention has the beneficial effects that:
1) the defects on the surface of the hard carbon are reduced by coating and roasting the hard carbon by adopting the asphalt, so that the side reaction of the electrolyte and the surface of the hard carbon is reduced, and the first effect is improved;
2) the addition of the carbon tube in the coating process improves the electronic conductivity of the hard carbon, reduces ohmic polarization and improves gram capacity;
3) the expansion of hard carbon is inhibited to a certain extent in the process of sodium ion deintercalation after coating, and the cycle stability is improved.
Drawings
The disclosure of the present invention is illustrated with reference to the accompanying drawings. It is to be understood that the drawings are designed solely for the purposes of illustration and not as a definition of the limits of the invention. In the drawings, like reference numerals are used to refer to like parts. Wherein:
fig. 1 is a first-turn charge and discharge curve of the modified coated biomass hard carbon negative electrode material prepared in example 1 of the present invention and the uncoated biomass hard carbon negative electrode material at a magnification of 0.1C.
Fig. 2 is a 150-cycle charge and discharge curve of the modified coated biomass hard carbon negative electrode material prepared in example 1 of the present invention and the uncoated biomass hard carbon negative electrode material at a magnification of 0.5C.
Detailed Description
It is easily understood that according to the technical solution of the present invention, a person skilled in the art can propose various alternative structures and implementation ways without changing the spirit of the present invention. Therefore, the following detailed description and the accompanying drawings are merely illustrative of the technical aspects of the present invention, and should not be construed as all of the present invention or as limitations or limitations on the technical aspects of the present invention.
For convenience, the method for preparing the hard carbon anode material with high first-efficiency and excellent cycle life by modification is divided into seven steps from A to G, and specifically comprises the following steps:
weighing 10 parts of NMP (1-methyl-2-pyrrolidone) and 10 parts of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 30-60 parts of organic solution, adding the organic solution into a conical heating stirrer at a rotating speed of 160-200r/min, simultaneously adding 40 parts of biomass hard carbon roasted at 1000-1300 ℃, and stirring for 2-4 hours;
c, weighing 2.4-4.8 parts of carbon tube slurry with solid content of 5%, adding the carbon tube slurry into the conical heating stirrer in the step B, stirring at the rotating speed of 160-200r/min for 1.5-3.5 h;
d, adding 8-16 parts of the asphalt solution in the step A into the mixture in the step C, and stirring for 3-5 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90-120 ℃, the rotating speed is 160-200r/min, and the heating time is 16-24 h;
f: roasting the mixture obtained in the step E in a CVD furnace, emptying for 1h at the inert gas flow rate of 5-8L/min, heating to 1000 ℃, and heating at the heating rate of 3-5 ℃/min; preserving the heat for 2-4h, and naturally cooling at an inert gas flow rate of 5-8L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
And B, placing the roasted biomass hard carbon into an organic solution, stirring to form a suspension of the biomass hard carbon in the organic solution, coating the suspension by the carbon tube slurry and the asphalt in the form of the suspension to enable the biomass hard carbon to be coated more uniformly, wherein the organic solution in the step B is preferably absolute ethyl alcohol, the absolute ethyl alcohol is low in cost and easy to obtain, is nontoxic, can be recovered after coating is finished, can be reused after treatment, and saves cost.
In the inert gas protection roasting process, the inert gas is preferably nitrogen. Firstly, nitrogen gas is the gas with the largest content in air, so that the nitrogen gas is easy to obtain, and the cost is low. And secondly, the hard carbon cathode material prepared by the method can be doped with N ions by using nitrogen for protection and roasting, and is favorable for sodium ion transmission to a certain extent.
The following embodiments are specifically described below.
Example 1 (comparative example)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 60kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tube slurry with solid content of 5 percent, adding the carbon tube slurry into the conical heating stirrer in the step B, stirring for 1.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
g, sieving the mixture obtained in the step F by a 300-mesh sieve to obtain a modified hard carbon negative electrode material for the sodium ion battery;
fig. 1 is a first-turn charge and discharge curve of the modified coated biomass hard carbon negative electrode material prepared in example 1 of the present invention and the uncoated biomass hard carbon negative electrode material at a magnification of 0.1C, and it can be seen that the gram capacity of the coated biomass hard carbon is about 300mAh/g, and the first efficiency increase is 87%;
fig. 2 is a cyclic charge-discharge curve of the modified coated biomass hard carbon negative electrode material and the uncoated biomass hard carbon negative electrode material prepared in example 1 of the present invention at a magnification of 0.5C, and after coating modification, the 0.5C gram capacity of the hard carbon is about 270mAh/g, and the cyclic stability is increased.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 2
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 30kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tubes with solid content of 5 percent, adding the carbon tubes into the conical heating stirrer in the step B, stirring the carbon tubes for 1.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 3 (adjustment of the rotational speed from 160r/min to 200r/min in step B)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 60kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 200r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tubes with solid content of 5 percent, adding the carbon tubes into the conical heating stirrer in the step B, stirring the carbon tubes for 1.5 hours at the rotating speed of 200 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, and stirring for 3 hours at the rotating speed of 200 r/min;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 200r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 4 (adjusting the absolute ethanol content in step B from 30kg to 60kg)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 60kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1300 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tubes with solid content of 5 percent, adding the carbon tubes into the conical heating stirrer in the step B, stirring the carbon tubes for 1.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 5 (adjusting the stirring time in step B for 2h to 4h)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 60kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 4 hours;
c, weighing 2.4kg of carbon tubes with solid content of 5 percent, adding the carbon tubes into the conical heating stirrer in the step B, stirring the carbon tubes for 1.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 6 (adjusting the stirring time from 1.5h to 3.5h in step C)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 60kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tubes with solid content of 5 percent, adding the carbon tubes into the conical heating stirrer in the step B, stirring the carbon tubes for 3.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 7 (adjusting the absolute ethanol content from 30kg to 60kg in step B and the stirring time from 3h to 5h in step D)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 60kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tubes with solid content of 5 percent, adding the carbon tubes into the conical heating stirrer in the step B, stirring the carbon tubes for 1.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 5 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 8 (adjusting the heating time from 24h to 16h in step E)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
weighing kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tubes with solid content of 5 percent, adding the carbon tubes into the conical heating stirrer in the step B, stirring the carbon tubes for 1.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 120 ℃, the rotating speed is 160r/min, and the heating time is 16 h;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 9 (adjusting the nitrogen flow rate in step F from 5L/min to 8L/min)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 60kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tubes with solid content of 5 percent, adding the carbon tubes into the conical heating stirrer in the step B, stirring the carbon tubes for 1.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at the nitrogen flow rate of 8L/min, emptying for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 8L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 10 (adjusting the temperature increase rate from 3 ℃/min to 5 ℃/min in step F)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
weighing kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tubes with solid content of 5 percent, adding the carbon tubes into the conical heating stirrer in the step B, stirring the carbon tubes for 1.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, and heating at a temperature rise rate of 5 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 11 (adjustment of the incubation time in step F from 4h to 2h)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 60kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tube slurry with solid content of 5 percent, adding the carbon tube slurry into the conical heating stirrer in the step B, stirring for 1.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 2 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 12 (adjusting the mass of the carbon tube in step C from 2.4kg to 4.8kg)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 60kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 4.8kg of carbon tube slurry with solid content of 5 percent, adding the carbon tube slurry into the conical heating stirrer in the step B, stirring for 1.5 hours at the rotating speed of 160 r/min;
d, adding 8kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
Example 13 (adjusting the mass of the asphalt solution added in step D from 8kg to 16kg)
A modification preparation method of a hard carbon negative electrode material for a sodium ion battery specifically comprises the following steps:
weighing 10kg of NMP (1-methyl-2-pyrrolidone) and 10kg of medium temperature coal tar pitch, adding into a double-planet stirrer, revolving for 40r/min, rotating for 2500r/min, and stirring for 5 h;
b, weighing 60kg of absolute ethyl alcohol, adding the absolute ethyl alcohol into a conical heating stirrer at the rotating speed of 160r/min, simultaneously adding 40kg of biomass hard carbon roasted at 1000 ℃, and stirring for 2 hours;
c, weighing 2.4kg of carbon tube slurry with solid content of 5 percent, adding the carbon tube slurry into the conical heating stirrer in the step B, stirring for 1.5 hours at the rotating speed of 160 r/min;
d, adding 16kg of the asphalt solution in the step A into the mixture in the step C, rotating at the speed of 160r/min, and stirring for 3 hours;
e: heating and evaporating the mixture obtained in the step D to dryness, wherein the heating temperature is 90 ℃, the rotating speed is 160r/min, and the heating time is 24 hours;
f: roasting the mixture obtained in the step E in a CVD furnace at a nitrogen flow rate of 5L/min, evacuating for 1h, heating to 1000 ℃, wherein the heating rate is 3 ℃/min; preserving heat for 4 hours, and naturally cooling at a nitrogen flow rate of 5L/min;
and G, sieving the mixture obtained in the step F by using a 300-mesh sieve to obtain the modified hard carbon negative electrode material for the sodium ion battery.
Mixing the prepared modified hard carbon negative electrode material with a binder PVDF and conductive carbon black SP according to a mass ratio of 95:2.5:2.5, preparing the mixture into slurry by using NMP (1-methyl-2-pyrrolidone), uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in vacuum at 80 ℃ for 24 hours to obtain the experimental battery pole piece. Then a sodium sheet is taken as a counter electrode, 0.8mol/L NaPF6 three-component mixed solvent is used, a CR2025 type button half cell is assembled in a vacuum glove box according to the conditions that EC and DMC are 1:1, the addition amount of FEC is 2% of the volume of EC and DMC, a polypropylene microporous membrane is taken as a diaphragm, the CR2025 type button half cell is discharged to 0V at a constant current of 0.1C, then discharged to 0V at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C, and the test procedure is circularly executed for 3 times; discharging to 0V at constant current of 0.5C, discharging to 0V at constant current of 0.02C, charging to 1.5V at constant current of 0.1C, and performing the test for 150 times.
As shown in the discharge curves of the uncoated hard carbon and the coated hard carbon in fig. 1, particularly, the uncoated hard carbon has a very obvious electrolyte film forming platform at about 0.75V, and the coated hard carbon disappears, so that the defect on the surface of the hard carbon is reduced by coating and roasting the hard carbon with asphalt, and the side reaction of the electrolyte and the surface of the hard carbon is further reduced, so that the first effect is improved.
Since the electron conductivity of hard carbon is poor, the electron conductivity of hard carbon is improved and the ohmic polarization is reduced by adding the carbon tube during the coating process, and the gram capacity is improved as shown by the charging curves of uncoated hard carbon and coated hard carbon in fig. 1.
As can be seen from the charge-discharge cycle curves of the coated hard carbon and the uncoated hard carbon of fig. 2, expansion of the hard carbon is suppressed to some extent in the process of sodium ion deintercalation after coating, and the cycle stability is improved.
The technical scope of the present invention is not limited to the above description, and those skilled in the art can make various changes and modifications to the above-described embodiments without departing from the technical spirit of the present invention, and such changes and modifications should fall within the protective scope of the present invention.
Claims (9)
1. A method for preparing a hard carbon negative electrode material with high first efficiency and excellent cycle life by modification is characterized by comprising the following steps:
s1, premixing 10 parts of NMP and 10 parts of medium-temperature coal tar pitch;
s2, placing 40 parts of biomass hard carbon into 30-60 parts of organic solution, stirring to prepare a suspension, adding 2.4-4.8 parts of carbon tube slurry into the suspension, and uniformly stirring;
s3, adding the pre-mixed asphalt solution in the S1 into the mixture obtained in the S2, and uniformly stirring;
and S4, heating and evaporating the mixture obtained in the step S3 to dryness, roasting and cooling the mixture in a CAD furnace under the protection of inert gas, and screening to obtain the modified hard carbon negative electrode material for the sodium ion battery.
2. The method for preparing the hard carbon anode material with high first efficiency and long cycle life according to claim 1, wherein the solid content of carbon tubes in the carbon tube slurry in S2 is 5%; and roasting the biomass hard carbon at the temperature of 1000-1300 ℃ before adding the biomass hard carbon into the stirrer.
3. The method for preparing the hard carbon negative electrode material with high first efficiency and long cycle life according to claim 1, wherein 8 to 16 parts of asphalt solution is added into S3, and the mixture is stirred with the mixture obtained in S2 for 3 to 5 hours.
4. The method for preparing the hard carbon negative electrode material with high first efficiency and long cycle life according to claim 1, wherein the flow rate of the inert gas is 5-8L/min during the roasting and cooling processes of the mixture in S4 under the protection of the inert gas; after cooling, the mixture was screened to 300 mesh.
5. The method for preparing the hard carbon anode material with high first efficiency and long cycle life according to claim 4, wherein the roasting temperature in the roasting process in S4 is 1000 ℃, wherein the heating rate is 3-5 ℃/min.
6. The method for preparing the hard carbon negative electrode material with high first efficiency and long cycle life according to claim 1, wherein in the premixing process of the NMP and the medium temperature coal tar pitch in S1, the NMP and the medium temperature coal tar pitch are added into a double planetary mixer, the revolution speed is set to be 40r/min, the self-rotation speed is set to be 2500r/min, and the mixing time is set to be 5 hours.
7. The method for preparing the hard carbon anode material with high first efficiency and long cycle life as claimed in claim 2, wherein the stirring speed is 160-200r/min and the stirring time is 2-4h during the suspension preparation in S2.
8. The method for preparing the hard carbon anode material with high first efficiency and long cycle life as claimed in claim 5, wherein in the step of heating and evaporating to dryness in S4, the heating temperature is 90-120 ℃, the heating time is 16-24h, the stirring state is maintained in the heating process, and the rotation speed is 160-200 r/min.
9. The method for preparing the hard carbon anode material with high first efficiency and long cycle life according to claim 8, wherein the inert gas is introduced for 1h before roasting in S4, and the hard carbon anode material is heated to 1000 ℃ during roasting, is kept warm for 2-4h, and is naturally cooled under the protection of the inert gas.
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| CN106299365A (en) * | 2016-11-04 | 2017-01-04 | 郑州大学 | A kind of sodium-ion battery biomass hard carbon cathode material, preparation method and sodium-ion battery |
| CN109360962A (en) * | 2018-10-24 | 2019-02-19 | 郑州中科新兴产业技术研究院 | A kind of lithium battery high stability silicon-carbon cathode material and preparation method thereof |
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| CN105633408A (en) * | 2016-03-11 | 2016-06-01 | 江西紫宸科技有限公司 | Preparation method of high-rate graphite anode material, anode material and lithium-ion battery |
| CN106299365A (en) * | 2016-11-04 | 2017-01-04 | 郑州大学 | A kind of sodium-ion battery biomass hard carbon cathode material, preparation method and sodium-ion battery |
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