CN115360339A - Modified hard carbon silicon carbon composite material, preparation method and application thereof, and lithium ion battery - Google Patents

Modified hard carbon silicon carbon composite material, preparation method and application thereof, and lithium ion battery Download PDF

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CN115360339A
CN115360339A CN202211130833.0A CN202211130833A CN115360339A CN 115360339 A CN115360339 A CN 115360339A CN 202211130833 A CN202211130833 A CN 202211130833A CN 115360339 A CN115360339 A CN 115360339A
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silicon
carbon
composite material
hard carbon
carbon composite
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徐士民
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Tianjin B&M Science and Technology Co Ltd
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Abstract

The invention relates to a modified hard carbon silicon carbon composite material, a preparation method and application thereof, and a lithium ion battery, wherein the modified hard carbon silicon carbon composite material comprises the following steps: mixing a hard carbon precursor with silicon monoxide to perform first calcination to prepare a hard carbon-silicon-carbon composite material; mixing the hard carbon silicon carbon composite material with the carbon nano tubes filled with the organic lithium compound for secondary calcination to prepare a pre-lithiated hard carbon silicon carbon composite material; and mixing the pre-lithiated hard carbon-silicon-carbon composite material with a nitrogen source, a phosphorus source and an organic polymer for third calcination. The steps are combined, so that when the prepared modified hard carbon-silicon-carbon composite material is used as a negative electrode material, the first cycle efficiency and the gram capacity are high, and the cycle performance is good.

Description

Modified hard carbon silicon carbon composite material, preparation method and application thereof, and lithium ion battery
Technical Field
The invention relates to the field of lithium ion batteries, in particular to a modified hard carbon silicon carbon composite material, a preparation method and application thereof, and a lithium ion battery.
Background
Lithium ion secondary batteries (LIBs) and sodium ion secondary batteries (NIBs) are increasingly used in digital, power and energy storage applications. The cathode materials of the traditional lithium ion secondary battery and sodium ion secondary battery comprise natural graphite, artificial graphite, hard carbon, soft carbon, silicon carbon, lithium titanate and the like; wherein, hard carbon is adopted as a negative electrode material, which shows better cycle performance, but the first cycle efficiency and gram capacity are lower.
Therefore, the hard carbon silicon carbon composite material which has high first cycle efficiency and gram volume and good cycle performance is provided, and the method has important significance.
Disclosure of Invention
Based on the above, the invention provides the modified hard carbon silicon carbon composite material which is high in first cycle efficiency and gram capacity and good in cycle performance, the preparation method and the application thereof, and the lithium ion battery.
The technical scheme of the invention for solving the technical problems is as follows.
A preparation method of a modified hard carbon silicon carbon composite material comprises the following steps:
mixing the hard carbon precursor with the silicon monoxide to carry out first calcination to prepare a hard carbon-silicon-carbon composite material;
mixing the hard carbon silicon carbon composite material with carbon nano tubes filled with organic lithium compounds for secondary calcination to prepare a pre-lithiated hard carbon silicon carbon composite material;
and mixing the pre-lithiated hard carbon-silicon-carbon composite material with a nitrogen source, a phosphorus source and an organic polymer for third calcination.
In some embodiments, in the preparation method of the modified hard carbon silicon carbon composite material, the preparation of the hard carbon precursor comprises the following steps:
and sequentially carrying out carbonization treatment and crushing treatment on the biomass material to prepare the hard carbon precursor.
In some embodiments, in the preparation method of the modified hard carbon-silicon-carbon composite material, the biomass material is selected from at least one of green walnut shells, mandarin oranges, peanut shells, coconut shells, starch, sugar cane, corn, sweet potatoes, seaweed, wheat straws, wood and fruit shells.
In some embodiments, in the preparation method of the modified hard carbon silicon carbon composite material, the mass ratio of the hard carbon precursor to the silicon monoxide is (3-100) to (0.01-30).
In some embodiments, the preparation method of the modified hard carbon-silicon-carbon composite material comprises the following steps:
mixing and refluxing the carbon nano tube, the organic lithium compound and the organic solvent.
In some embodiments, in the preparation method of the modified hard carbon-silicon-carbon composite material, the diameter of the carbon nanotube is 3nm to 100nm.
In some embodiments, in the preparation method of the modified hard carbon-silicon-carbon composite material, the mass ratio of the hard carbon-silicon-carbon composite material to the carbon nanotubes filled with the organic lithium compound is (2-100): (0.01-20).
In some embodiments, in the preparation method of the modified hard carbon-silicon-carbon composite material, the mass ratio of the pre-lithiated hard carbon-silicon-carbon composite material, the nitrogen source, the phosphorus source and the organic polymer is (2-100): 0.1-20: 0.2-50.
In some of these embodiments, the modified hard silicon carbon composite is prepared by a method wherein the nitrogen source is selected from at least one of ammonia, ethylenediamine, propylenediamine, butylenediamine, hexylenediamine, urea, pyridine, pyrrole, a nitrogen-containing ionic liquid, ammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonium carbonate, and ammonium hydrogen carbonate.
In some of these embodiments, the method of making the modified hard carbon silicon carbon composite material includes selecting the phosphorus source from at least one of elemental phosphorus, phosphorus pentoxide, lithium phosphate, ammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, and calcium phosphate.
In some of the embodiments, in the method for preparing the modified hard carbon-silicon-carbon composite material, the organic polymer is at least one selected from epoxy resin, phenolic resin, polystyrene, polymethyl methacrylate, polyaniline, polyvinyl alcohol and asphalt.
In some embodiments, in the preparation method of the modified hard carbon-silicon-carbon composite material, the temperature of the first calcination is 500-1500 ℃, and the time is 5-40 h.
In some embodiments, in the preparation method of the modified hard carbon-silicon-carbon composite material, the temperature of the second calcination is 200-1000 ℃ and the time is 1-20 h.
In some embodiments, in the preparation method of the modified hard carbon-silicon-carbon composite material, the temperature of the third calcination is 300-1500 ℃, and the time is 1-15 h.
In some embodiments, the method for preparing a modified hard carbon-silicon-carbon composite material further comprises a step of coating the obtained doped pre-lithiated hard carbon-silicon-carbon composite material after the third calcination step.
In some of the embodiments, in the preparation method of the modified hard carbon silicon carbon composite material, the coating treatment comprises the following steps:
and mixing the doped prelithiated hard carbon-silicon-carbon composite material and a coating agent, wherein the coating agent is selected from at least one of oxide, fluoride and phosphate, and performing fourth calcination.
In some of the embodiments, in the method for preparing the modified hard carbon silicon carbon composite material, the oxide is at least one selected from the group consisting of titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide, iron oxide, niobium oxide, tungsten oxide, strontium oxide, copper oxide, cerium oxide, and yttrium oxide.
In some of these embodiments, in the method of preparing the modified hard carbon silicon carbon composite material, the fluoride is selected from at least one of aluminum fluoride, zirconium fluoride, magnesium fluoride, calcium fluoride, lithium fluoride, sodium fluoride, and potassium fluoride.
In some of the embodiments, in the method for preparing the modified hard carbon silicon carbon composite material, the phosphate is at least one selected from the group consisting of lithium phosphate, sodium phosphate, aluminum phosphate, zirconium phosphate, calcium phosphate and potassium phosphate.
The invention also provides a modified hard carbon silicon carbon composite material, which comprises a pre-lithiation hard carbon silicon carbon composite material A and a first coating layer B arranged on the surface of the A;
a comprisesUniformly dispersed lithium complex a 1 And hard carbon silicon carbon composite material a 2 ；
a 1 The method comprises the following steps: carbon nanotubes and lithium compounds and carbon materials filled in the carbon nanotubes;
a 2 the method comprises the following steps: hard carbon, nano silicon and silicon dioxide, wherein the nano silicon and part of the silicon dioxide are dispersed in the hard carbon, and part of the silicon dioxide is coated on the surfaces of the hard carbon and nano silicon particles.
B comprises nitrogen and phosphorus doped pyrolytic carbon.
In some of these embodiments, the modified hard carbon silicon carbon composite is doped with nitrogen and phosphorus elements.
In some of these embodiments, in the modified hard carbon silicon carbon composite material, a surface of the first coating layer is provided with a second coating layer comprising at least one of an oxide, a fluoride, and a phosphate.
The invention provides a modified hard carbon silicon carbon composite material prepared by the preparation method of the modified hard carbon silicon carbon composite material or an application of the modified hard carbon silicon carbon composite material in the preparation of a lithium ion battery.
The invention provides a lithium ion battery which comprises a positive electrode, a diaphragm and a negative electrode, wherein the positive electrode and the negative electrode are arranged on two sides of the diaphragm, and the negative electrode is made of the modified hard carbon-silicon-carbon composite material.
Compared with the prior art, the preparation method of the modified hard carbon silicon carbon composite material has the following beneficial effects:
according to the preparation method of the modified hard carbon silicon carbon composite material, after the hard carbon precursor and the silicon monoxide are mixed and subjected to first calcination, the crystal structure stability of the hard carbon can be effectively improved; the modified hard carbon-silicon-carbon composite material is characterized in that silicon monoxide is disproportionated to generate nano silicon and silicon dioxide, part of the silicon dioxide and the nano silicon are uniformly distributed in a hard carbon structure, the volume change of the modified hard carbon-silicon-carbon composite material in the charging and discharging process is effectively relieved, the other part of the silicon dioxide is coated on the surfaces of nano silicon and hard carbon particles, the erosion of electrolyte to the nano silicon and the hard carbon is effectively relieved, and therefore the first-time circulation efficiency of the modified hard carbon-silicon-carbon composite material is effectively improved; furthermore, the prepared hard carbon-silicon-carbon composite material and the carbon nano tube filled with the organic lithium compound are mixed for secondary calcination, and the organic lithium compound is filled in the carbon nano tube, so that the organic lithium compound can be effectively prevented from contacting with oxygen, nitrogen, carbon dioxide and moisture in the air to generate side reaction, and the organic lithium compound loses reactivity, and the stability of the organic lithium compound is effectively improved; after the second calcination, the carbon-hydrogen element is converted into a carbon material and is compounded with the lithium element in the carbon nano tube, such as LiCx, so that the stability of the organic lithium compound is further improved; the carbon nano tubes are uniformly dispersed in the hard carbon-silicon-carbon composite material, the lithium element in the carbon nano tubes provides rich lithium sources in the form of simple substance lithium and oxidation state, irreversible lithium loss is supplemented in the charging and discharging process, and the first cycle efficiency and gram capacity of the modified hard carbon-silicon-carbon composite material are effectively improved; mixing the prepared pre-lithiation hard carbon silicon carbon composite material with a nitrogen source, a phosphorus source and an organic polymer to carry out third calcination, doping nitrogen and phosphorus in the pre-lithiation hard carbon silicon carbon composite material, and respectively forming ionic bonds or covalent bonds with lithium and carbon, so that the surface of the modified hard carbon silicon carbon composite material is in contact with an electrolyte to carry out electrochemical reaction to form a solid electrolyte membrane in a circulating process, the embedding of metal ions of a positive electrode material is effectively reduced, and the circulating performance of the modified hard carbon silicon carbon composite material is effectively improved; and the carbon nitride, the lithium nitride, the silicon nitride, the lithium phosphide, the carbon phosphide and the silicon phosphide which are respectively formed by the nitrogen and the phosphorus and the lithium and the carbon have conductivity, so that the conductivity of the modified hard carbon-silicon-carbon composite material is effectively improved; the organic polymer is carbonized and decomposed and is uniformly distributed on the surface of the pre-lithiated hard carbon-silicon-carbon composite material, and a nitrogen and phosphorus doped pyrolytic carbon layer is formed on the surface of the pre-lithiated hard carbon-silicon-carbon composite material, so that the side reaction of the modified hard carbon-silicon-carbon composite material can be effectively reduced, and the irreversible capacity loss in the circulating process is reduced; and simultaneously, the conductivity of the modified hard carbon-silicon-carbon composite material is improved. The steps are combined, so that when the prepared modified hard carbon silicon carbon composite material is used as a negative electrode material, the first cycle efficiency and the gram capacity are high, and the cycle performance is good.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is an SEM photograph of n-butyllithium-filled carbon nanotubes prepared in step (1) of example 1;
FIG. 2 is an SEM image of a black hard carbon/silicon carbon composite prepared in step (3) of example 1;
FIG. 3 is an SEM image of a modified hard carbon-silicon-carbon composite material prepared in step (6) of example 1;
FIG. 4 is an SEM image of a modified hard carbon-silicon-carbon composite material prepared in step (6) of example 2;
fig. 5 is a graph of the cycle capacity retention of button cells made from the modified hard carbon silicon carbon composite made in example 1;
fig. 6 is a graph of the cycle capacity retention of button cells made from the modified hard carbon silicon carbon composite made in example 2;
fig. 7 is a graph comparing the retention rate of the cycle capacity of thin film batteries manufactured from the modified hard carbon silicon carbon composites of examples 1 to 5 and comparative examples 1 to 5.
Detailed Description
The technical solution of the present invention will be further described in detail with reference to the following specific examples. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. It is to be understood that these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In the description of the present invention, it is to be understood that the terms "first", "second", and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to imply that the number of technical features indicated are in fact significant. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
The weight of the related components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present invention as long as it is in accordance with the description of the embodiments of the present invention. Specifically, the weight described in the description of the embodiment of the present invention may be a unit of mass known in the chemical industry field, such as μ g, mg, g, and kg.
The embodiment of the invention provides a preparation method of a modified hard carbon silicon carbon composite material, which comprises the steps of S10-S30.
Step S10: and mixing the hard carbon precursor with the silicon monoxide to perform first calcination to prepare the hard carbon-silicon-carbon composite material.
Through mixing hard carbon precursor and inferior silicon oxide and carrying out first calcination, inferior silicon oxide disproportionation generates nanometer silicon and silica, and partial silica and nanometer silicon evenly distributed are in hard carbon structure, effectively alleviate the volume change of modified hard carbon silicon carbon composite material in the charge-discharge process, and another part silica cladding is on nanometer silicon and hard carbon particle surface, effectively alleviates the erosion of electrolyte to nanometer silicon and hard carbon to effectively improve modified hard carbon silicon carbon composite material's first cycle efficiency.
In some examples, the mass ratio of the hard carbon precursor to the silicon monoxide in step S10 is (3-100): 0.01-30.
In some examples, in step S10, the mass ratio of the hard carbon precursor to the silicon monoxide is (3-100): 1.
It can be understood that the mass ratio of hard carbon precursor to silica includes but is not limited to 3:1, 4:1, 5:1, 5.7.
Alternatively, in step S10, the mass ratio of the hard carbon precursor to the silicon monoxide is (3-10): 1.
Further, in step S10, the mass ratio of the hard carbon precursor to the silicon monoxide is (3-6): 1.
In some examples, in step S10, the temperature of the first calcination is 500 ℃ to 1500 ℃ for 5h to 40h.
It is understood that the temperature of the first calcination includes, but is not limited to, 500 deg.C, 550 deg.C, 600 deg.C, 650 deg.C, 700 deg.C, 750 deg.C, 800 deg.C, 850 deg.C, 900 deg.C, 950 deg.C, 1000 deg.C, 1100 deg.C, 1200 deg.C, 1300 deg.C, 1500 deg.C; times include, but are not limited to, 5h, 8h, 10h, 12h, 15h, 18h, 20h, 25h, 30h, 35h, 40h.
Optionally, the temperature of the first calcination is 800-1200 ℃, and the time is 8-20 h.
In some examples, in step S10, a first calcination is performed under a protective atmosphere.
Further, the protective atmosphere is selected from at least one of nitrogen, helium, and argon.
In some examples, in step S10, the preparation of the hard carbon precursor includes step S11.
Step S11: and sequentially carrying out carbonization treatment and crushing treatment on the biomass material to prepare a hard carbon precursor.
In some examples, in step S11, the temperature of the carbonization treatment is 100 ℃ to 500 ℃ for 3 hours to 20 hours.
It is understood that the temperature of the carbonization treatment includes, but is not limited to, 100 deg.C, 150 deg.C, 200 deg.C, 250 deg.C, 300 deg.C, 350 deg.C, 400 deg.C, 450 deg.C, 500 deg.C; the carbonization time includes but is not limited to 3h, 5h, 10h, 12h, 15h, 18h and 20h.
Optionally, the temperature of the carbonization treatment is 300-400 DEG C
In some examples, the carbonization process is performed in a vacuum or a protective atmosphere in step S11.
Further, the protective atmosphere is selected from at least one of nitrogen, helium, and argon.
It can be understood that the product after carbonization treatment is crushed to obtain the granular hard carbon precursor.
In some of these examples, the biomass material in step S11 is a biomass material rich in phenyl functional groups.
In some examples, in step S11, the biomass material is selected from at least one of green walnut husks, mandarin oranges, peanut shells, starch, coconut shells, sugar cane, corn, sweet potatoes, seaweed, wheat straw, wood, and fruit shells.
It can be understood that walnut green husks, mandarin oranges, peanut shells, starch, sugarcane, coconut shells, corn, sweet potatoes, seaweed, wheat straws, wood and fruit shells respectively contain different contents of benzene ring structure compounds.
The walnut green husk is waste of walnut industry and contains rich compounds with benzene ring structures, such as total polyphenol, flavone, polysaccharide and the like. The total polyphenol content of the walnut green husk juice and the green husk residue is more than 100mg/g, and the flavone content is more than 60mg/g, so the walnut green husk juice and the green husk residue are better hard carbon material sources.
The biomass material is rich in a phenyl functional group structure, and after the biomass material is mixed with the silicon oxide and calcined, the stability of the crystal structure of the hard carbon can be effectively improved, and the cycle performance of the modified hard carbon-silicon-carbon composite material is further improved.
Step S20: and (4) mixing the hard carbon-silicon-carbon composite material prepared in the step (S10) with the carbon nano tubes filled with the organic lithium compound, and performing secondary calcination to prepare the pre-lithiated hard carbon-silicon-carbon composite material.
The hard carbon-silicon-carbon composite material and the carbon nano tubes filled with the organic lithium compound are mixed for secondary calcination, the carbon nano tubes filled with the organic lithium compound are uniformly dispersed in the hard carbon-silicon-carbon composite material, and the organic lithium compound is filled in the carbon nano tubes, so that the organic lithium compound can be effectively prevented from being contacted with oxygen, nitrogen, carbon dioxide and moisture in the air to generate side reaction, the organic lithium compound loses reactivity, and the stability of the organic lithium compound is effectively improved; after the second calcination, the carbon-hydrogen element is converted into a carbon material and is compounded with the lithium element in the carbon nano tube, such as LiCx, so that the stability of the organic lithium compound is further improved; the carbon nano tubes are uniformly dispersed in the hard carbon-silicon-carbon composite material, the lithium element in the carbon nano tubes provides abundant lithium sources in the form of simple substance lithium and oxidation state, irreversible lithium resources are supplemented in the charging and discharging process, and the first cycle efficiency and gram capacity of the modified hard carbon-silicon-carbon composite material are effectively improved.
In some examples, in step S20, the mass ratio of the hard carbon silicon carbon composite material to the carbon nanotubes filled with the organolithium compound is (2-100): 0.01-20.
Optionally, in step S20, the mass ratio of the hard carbon-silicon-carbon composite material to the carbon nanotubes filled with the organolithium compound is (2-100): 1.
It can be understood that the mass ratio of the hard carbon silicon carbon composite material to the carbon nanotubes filled with the organolithium compound includes but is not limited to 2:1, 3:1, 4:1, 5:1, 5.7.
In step S20, the mass ratio of the hard carbon-silicon-carbon composite material to the carbon nanotubes filled with the organolithium compound is (5-20): 1.
In some examples, in step S20, the temperature of the second calcination is 200 ℃ to 1000 ℃ for 1h to 20h.
It is understood that the temperature of the second calcination includes, but is not limited to, 200 deg.C, 300 deg.C, 400 deg.C, 500 deg.C, 550 deg.C, 600 deg.C, 650 deg.C, 700 deg.C, 750 deg.C, 800 deg.C, 850 deg.C, 900 deg.C, 950 deg.C, 1000 deg.C; times include, but are not limited to, 1h, 3h, 5h, 8h, 10h, 12h, 15h, 18h, 20h.
Alternatively, in step S20, the temperature of the second calcination is 400 to 800 ℃.
In some examples, in step S20, a second calcination is performed under a protective atmosphere.
Further, the protective atmosphere is selected from at least one of nitrogen, helium, and argon.
In some examples, in step S20, the product obtained from the second calcination is pulverized.
In some examples, the preparation of the carbon nanotubes filled with the organolithium compound in step S20 includes step S21.
Step S21: mixing and refluxing the carbon nano tube, the organic lithium compound and the organic solvent.
In some examples, the carbon nanotubes have a diameter of 3nm to 100nm in step S21.
In some examples, in step S21, at least one end of the carbon nanotube is open.
In some examples, in step S21, the organolithium compound is selected from at least one of substituted or unsubstituted methyllithium, ethyllithium, butyllithium, hexyllithium, phenyllithium, tolyllithium, xylenyllithium, triphenyllithium, and naphthyllithium.
In some examples, in step S21, the organic solvent is selected from at least one of an ether solvent, tetrahydrofuran, a tetrahydrofuran derivative, benzene, toluene, xylene, and trimethylbenzene.
It is understood that ethereal solvents include, but are not limited to, diethyl ether, propylene oxide, and the like.
Further, in step S21, the organic solvent is tetrahydrofuran.
In some examples, the step S21 further includes adding at least one of an alkane derivative and an aromatic hydrocarbon derivative to the mixed reflux process.
Further, the alkane derivative is halogenated alkane, and the aromatic hydrocarbon derivative is halogenated aromatic hydrocarbon.
In some examples, in step S21, the reflow is performed in a vacuum or a protective gas.
In some examples, in step S21, the reflux temperature is 100 ℃ to 200 ℃ and the time is 3h to 100h.
In some examples, in step S21, after the reflux is finished, the reaction solution is sequentially filtered, washed, and dried. Further, washing was performed with petroleum ether.
It is understood that the product obtained in step S21 is a carbon nanotube filled with an organolithium compound.
Step S30: and (4) mixing the pre-lithiated hard carbon-silicon-carbon composite material prepared in the step (S20) with a nitrogen source, a phosphorus source and an organic polymer, and performing third calcination to obtain the doped pre-lithiated hard carbon-silicon-carbon composite material.
The pre-lithiated hard carbon-silicon-carbon composite material is mixed with a nitrogen source, a phosphorus source and an organic polymer to be subjected to third calcination, nitrogen and phosphorus are doped in the pre-lithiated hard carbon-silicon-carbon composite material and form ionic bonds or covalent bonds with lithium and carbon respectively, so that the surface of the modified hard carbon-silicon-carbon composite material is in contact with an electrolyte to generate electrochemical reaction to form a solid electrolyte membrane in the circulating process, the embedding of metal ions in a positive electrode material is effectively reduced, and the circulating performance of the modified hard carbon-silicon-carbon composite material is effectively improved; and the carbon nitride, the lithium nitride, the silicon nitride, the lithium phosphide, the carbon phosphide and the silicon phosphide which are respectively formed by the nitrogen and the phosphorus and the lithium and the carbon have conductivity, so that the conductivity of the modified hard carbon-silicon-carbon composite material is effectively improved; the organic polymer is carbonized and decomposed and is uniformly distributed on the surface of the pre-lithiated hard carbon-silicon-carbon composite material, and a nitrogen and phosphorus doped pyrolytic carbon layer is formed on the surface of the pre-lithiated hard carbon-silicon-carbon composite material, so that the side reaction of the modified hard carbon-silicon-carbon composite material can be effectively reduced, and the irreversible capacity loss in the circulating process is reduced; and simultaneously, the conductivity of the modified hard carbon-silicon-carbon composite material is improved.
In some examples, in step S30, the mass ratio of the pre-lithiated hard carbon-silicon-carbon composite material, the nitrogen source, the phosphorus source and the organic polymer is (2-100): 0.1-20): 0.2-50.
It will be appreciated that a substance may comprise both elemental nitrogen and elemental phosphorus, i.e. in this case the source of nitrogen and the source of phosphorus may be the same substance. At the moment, the mass ratio of the pre-lithiated hard carbon-silicon-carbon composite material to the total mass of the nitrogen source and the phosphorus source and the organic polymer is (2-100): (0.2-40): 0.2-50).
It is further understood that setting the mass of the nitrogen source to 1, the mass of the pre-lithiated hard carbon silicon carbon composite material includes, but is not limited to, 2, 5, 10, 20, 30, 40, 50, 60, 80, 100; the quality of the phosphorus source includes, but is not limited to, 0.1, 0.5, 1, 2, 5, 10, 20; the mass of the organic polymer includes, but is not limited to, 0.2, 0.5, 1, 2, 5, 10, 15, 20, 30, 40, 50.
In some examples, in step S30, the nitrogen source is selected from at least one of ammonia, ethylenediamine, propylenediamine, butylenediamine, hexylenediamine, urea, pyridine, pyrrole, nitrogen-containing ionic liquid, ammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonium carbonate, and ammonium hydrogen carbonate.
In some examples, in step S30, the phosphorus source is selected from at least one of elemental phosphorus, phosphorus pentoxide, lithium phosphate, ammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, and calcium phosphate.
In some examples, in step S30, the organic polymer is at least one selected from epoxy resin, phenolic resin, polystyrene, polymethyl methacrylate, polyaniline, polyvinyl alcohol, and asphalt.
The benzene ring structure contained in the organic polymer is decomposed into a hard carbon structure in the pyrolysis process, has higher interlayer spacing than common graphite, and can improve the ion intercalation and migration rate.
In some examples, in step S30, the temperature of the third calcination is 300 ℃ to 1500 ℃ for 1h to 15h.
It is understood that the temperature of the first calcination includes, but is not limited to, 300 deg.C, 350 deg.C, 400 deg.C, 500 deg.C, 550 deg.C, 600 deg.C, 650 deg.C, 700 deg.C, 750 deg.C, 800 deg.C, 850 deg.C, 900 deg.C, 950 deg.C, 1000 deg.C, 1100 deg.C, 1200 deg.C, 1300 deg.C, 1500 deg.C; times include, but are not limited to, 1h, 3h, 5h, 8h, 10h, 12h, 15h.
Alternatively, in step S30, the temperature of the third calcination is 400 to 1000 ℃.
In some examples, in step S30, a third calcination is performed under a protective atmosphere.
Further, the protective atmosphere is selected from at least one of nitrogen, helium, and argon.
In some examples, in step S30, the product obtained from the third calcination is pulverized.
In some examples, the method for preparing the modified hard carbon-silicon-carbon composite material further comprises step S40.
Step S40: and (4) coating the doped pre-lithiated hard carbon-silicon-carbon composite material obtained in the step (S30).
The doped pre-lithiation hard carbon-silicon-carbon composite material is coated to obtain the coated doped pre-lithiation hard carbon-silicon-carbon composite material, so that the protection capability of the modified hard carbon-silicon-carbon composite material can be further improved.
In some examples, the coating process in step S40 includes the steps of:
and mixing the doped prelithiated hard carbon-silicon-carbon composite material and a coating agent, wherein the coating agent is selected from at least one of oxide, fluoride and phosphate, and performing fourth calcination.
In some examples, in step S40, the oxide is selected from at least one of titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide, iron oxide, niobium oxide, tungsten oxide, strontium oxide, copper oxide, cerium oxide, and yttrium oxide.
In some examples, in step S40, the fluoride is selected from at least one of aluminum fluoride, zirconium fluoride, magnesium fluoride, calcium fluoride, lithium fluoride, sodium fluoride, and potassium fluoride.
In some examples, in step S40, the phosphate is selected from at least one of lithium phosphate, sodium phosphate, aluminum phosphate, zirconium phosphate, calcium phosphate, and potassium phosphate.
By controlling the type of the coating agent, the side reaction of the electrolyte to the negative electrode material can be further prevented or reduced, and the coulomb efficiency and the cycle performance of the modified hard carbon-silicon-carbon composite material are improved.
In some examples, the mass ratio of the doped prelithiated hard carbon-silicon-carbon composite material to the capping agent in step S40 is (1-100): (0.001-20).
In some examples, the mass ratio of the doped prelithiated hard carbon-silicon-carbon composite material to the capping agent in step S40 is 1 (0.001-20).
It can be understood that the mass ratio of the doped prelithiated hard carbon silicon carbon composite material to the capping agent includes but is not limited to 0.001.
Optionally, in step S40, the mass ratio of the doped pre-lithiated hard carbon-silicon-carbon composite material to the coating agent is 1 (0.01-0.15).
In some examples, in step S40, the fourth calcination is performed at a temperature of 200 ℃ to 1000 ℃ for 1h to 15h.
It is understood that the temperature of the fourth calcination includes, but is not limited to, 200 deg.C, 300 deg.C, 400 deg.C, 500 deg.C, 550 deg.C, 600 deg.C, 650 deg.C, 700 deg.C, 750 deg.C, 800 deg.C, 850 deg.C, 900 deg.C, 950 deg.C, 1000 deg.C; times include, but are not limited to, 1h, 3h, 5h, 8h, 10h, 12h, 15h.
Optionally, the fourth calcining temperature is 400-800 ℃, and the time is 5-12 h.
In some examples, in step S40, a first calcination is performed under a protective atmosphere.
Further, the protective atmosphere is selected from at least one of nitrogen, helium, and argon.
In some examples, in step S40, the product obtained by the fourth calcination is pulverized.
The preparation method of the modified hard carbon silicon carbon composite material has the advantages that the steps are combined, so that when the prepared modified hard carbon silicon carbon composite material is used as a negative electrode material, the first cycle efficiency and gram capacity are high, and the cycle performance and the high-low temperature performance are good.
The embodiment of the invention provides a modified hard carbon silicon carbon composite material, which is prepared by the preparation method of the modified hard carbon silicon carbon composite material.
The invention provides a modified hard carbon silicon carbon composite material, which comprises a pre-lithiated hard carbon silicon carbon composite material A and a first coating layer B arranged on the surface of the A;
a comprises uniformly dispersed lithium complexes a 1 And hard carbon silicon carbon composite material a 2 ；
a 1 The method comprises the following steps: carbon nanotubes and lithium compounds and carbon materials filled in the carbon nanotubes;
a 2 the method comprises the following steps: hard carbon, nano silicon and silicon dioxide, wherein the nano silicon and part of the silicon dioxide are dispersed in the hard carbon, and part of the silicon dioxide is coated on the surfaces of the hard carbon and nano silicon particles;
b comprises nitrogen and phosphorus doped pyrolytic carbon.
In some of these examples, the modified hard carbon silicon carbon composite material is pre-lithiated hard carbon silicon carbon composite material doped with a nitrogen element and a phosphorous element.
It is understood that the lithium complex a 1 And hard carbon silicon carbon composite material a 2 Doped with nitrogen and phosphorus.
In some of these examples, the modified hard carbon silicon carbon composite material wherein the surface of the first cladding layer is provided with a second cladding layer comprising at least one of an oxide, a fluoride, and a phosphate.
An embodiment of the invention provides a modified hard carbon silicon carbon composite material prepared by the preparation method of the modified hard carbon silicon carbon composite material or an application of the modified hard carbon silicon carbon composite material in preparation of a lithium ion battery. The invention also provides a lithium ion battery cathode material which comprises the modified hard carbon silicon carbon composite material prepared by the preparation method of the modified hard carbon silicon carbon composite material or the modified hard carbon silicon carbon composite material.
The modified hard carbon silicon carbon composite material prepared by the preparation method of the modified hard carbon silicon carbon composite material or the modified hard carbon silicon carbon composite material is used for preparing the lithium ion battery cathode material, and can endow the lithium ion battery cathode material with higher first cycle efficiency and gram capacity.
In some embodiments, the lithium ion battery negative electrode material may be a modified hard carbon silicon carbon composite material prepared by the preparation method of the modified hard carbon silicon carbon composite material or the modified hard carbon silicon carbon composite material, that is, the lithium ion battery negative electrode material is directly prepared from the modified hard carbon silicon carbon composite material prepared by the preparation method of the modified hard carbon silicon carbon composite material or the modified hard carbon silicon carbon composite material. In other embodiments, the lithium ion battery cathode material may include other materials besides the modified hard carbon silicon carbon composite material prepared by the preparation method of the modified hard carbon silicon carbon composite material or the modified hard carbon silicon carbon composite material.
The invention provides a lithium ion battery, which comprises a positive electrode, a diaphragm and a negative electrode, wherein the positive electrode and the negative electrode are arranged on two sides of the diaphragm, and the material of the negative electrode comprises a modified hard carbon silicon carbon composite material prepared by the preparation method of the modified hard carbon silicon carbon composite material or the modified hard carbon silicon carbon composite material.
An embodiment of the present invention provides an application of the lithium ion battery in an electronic device, an electric tool, an electric vehicle, or a power storage system. Another embodiment of the present invention provides an electronic device, an electric tool, an electric vehicle, or an electric power storage system including the lithium ion battery described above.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The modified hard carbon silicon carbon composite material, the preparation method and the application thereof, and the lithium ion battery are exemplified below, and it is understood that the modified hard carbon silicon carbon composite material, the preparation method and the application thereof, and the lithium ion battery are not limited to the following examples.
In the examples below, the surface topography was carried out on a scanning electron microscope SEM of model JSM-6510, JEOL, and EV018, zeiss, germany, and D50 was carried out on a Mark Mastersizer 2000 laser particle sizer, united kingdom.
The following examples used anhydrous tetrahydrofuran with the following water removal procedure: putting tetrahydrofuran into a distillation flask, adding metal sodium at the bottom, vacuumizing, heating to 150 ℃, and refluxing for 48 hours to obtain anhydrous tetrahydrofuran.
Example 1
(1) Putting 1000mL of anhydrous tetrahydrofuran into a round-bottom flask, adding 100g of multi-walled carbon nano tube (the inner diameter is 10nm, the tube length is more than 50 mu m), 5g of metal lithium and 30g of n-butyl chloride, adding stirring magnetons, vacuumizing, stirring and refluxing for 20h at 180 ℃, cooling to room temperature, filtering under the protection of argon, washing for 3 times by using petroleum ether, draining, preparing the carbon nano tube filled with n-butyl lithium, and sealing and storing; an SEM image of the prepared n-butyllithium-filled carbon nanotubes is shown in fig. 1;
(2) Cleaning 2000g of walnut green peel, drying, carbonizing at 400 ℃ in nitrogen atmosphere, mechanically crushing, and sieving with a 100-mesh sieve to prepare 1140g of hard carbon precursor;
(3) Uniformly stirring and mixing 1140g of the hard carbon precursor obtained in the step (2) and 200g of silicon monoxide (99.0%) by using absolute ethyl alcohol, drying, mechanically crushing, sieving by using a 50-mesh sieve, placing in a muffle furnace, heating to 1100 ℃ at a heating rate of 5 ℃/min in the muffle furnace under a nitrogen atmosphere, preserving heat for 8 hours, naturally cooling to room temperature, mechanically crushing, sieving by using a 100-mesh sieve, and preparing to obtain a black hard carbon/silicon carbon composite material, wherein an SEM picture of the black hard carbon/silicon carbon composite material is shown in figure 2;
(4) Uniformly mixing 1000g of the hard carbon/silicon carbon composite material obtained in the step (3) and 50g of the carbon nano tube filled with n-butyllithium obtained in the step (1) in a nitrogen atmosphere, placing the mixture in a muffle furnace, heating the mixture to 400 ℃ at a heating rate of 3 ℃/min in the muffle furnace in the nitrogen atmosphere, preserving the temperature for 5 hours, naturally cooling the mixture to room temperature, mechanically crushing the mixture, and sieving the crushed mixture with a 100-mesh sieve to prepare a black pre-lithiated hard carbon/silicon carbon composite material;
(5) Uniformly mixing 1000g of the pre-lithiated hard carbon/silicon carbon composite material obtained in the step (4), 20g of ethylenediamine, 10g of phosphorus pentoxide and 200g of phenolic resin particles with absolute ethyl alcohol, stirring, drying, mechanically crushing, sieving by a 50-mesh sieve, placing in a muffle furnace, heating in a nitrogen atmosphere at a heating rate of 5 ℃/min, heating to 1200 ℃, keeping the temperature for 10 hours, naturally cooling to room temperature, mechanically crushing, sieving by a 400-mesh sieve, and preparing to obtain a black nitrogen-phosphorus-doped pre-lithiated hard carbon/silicon carbon composite material;
(6) And (3) uniformly mixing 1000g of the black nitrogen-phosphorus doped pre-lithiated hard carbon/silicon carbon composite material obtained in the step (5), 5g of alumina, 3g of magnesium fluoride and 5g of lithium phosphate in a high-speed mixer, heating to 500 ℃ at a muffle furnace heating rate of 3 ℃/min, keeping the temperature for 8 hours, naturally cooling to room temperature, mechanically crushing, and sieving with a 400-mesh sieve to obtain the nitrogen-phosphorus doped pre-lithiated hard carbon/silicon carbon composite material coated with the black aluminum oxide-magnesium fluoride-lithium phosphate, namely the modified hard carbon-silicon carbon composite material, wherein an SEM image of the modified hard carbon-silicon carbon composite material is shown in FIG. 3.
Example 2
Basically the same as example 1, except that:
(1) The n-butyl chloride in example 1 was replaced with an equal amount of benzyl chloride;
(2) The biomass material comprises 1000g of walnut green husks and 1000g of straws;
(3) Stirring 1000g of hard carbon precursor and 300g of silica (99.0%) by using absolute ethyl alcohol, and uniformly mixing;
(4) Uniformly mixing 1000g of the hard carbon/silicon carbon composite material obtained in the step (3) and 100g of the carbon nano tube filled with n-butyl lithium obtained in the step (1) in a nitrogen atmosphere;
(5) Stirring and uniformly mixing 1000g of the pre-lithiated hard carbon/silicon carbon composite material obtained in the step (4), 10g of ammonium phosphate, 100g of epoxy resin, 100g of polymethyl methacrylate and 100g of petroleum asphalt particles by using absolute ethyl alcohol;
(6) Uniformly mixing 1000g of the black nitrogen-phosphorus doped pre-lithiated hard carbon/silicon-carbon composite material obtained in the step (5), 5g of titanium oxide and 5g of sodium phosphate in a high-speed mixer;
the SEM image of the finally prepared modified hard carbon silicon carbon composite material is shown in fig. 4.
Example 3
Basically the same as example 1, except that:
(1) Multi-walled carbon nanotubes (internal diameter 7nm, tube length >70 μm), n-butyl chloride in example 1 was replaced with an equal amount of naphthol;
(2) The biomass materials are 400g of sugarcane stalks, sweet potatoes and corn stalks respectively;
(4) Uniformly mixing 1000g of the hard carbon/silicon carbon composite material obtained in the step (3) and 200g of the carbon nano tube filled with n-butyllithium obtained in the step (1) in a nitrogen atmosphere, placing the mixture in a muffle furnace, heating the mixture in the nitrogen atmosphere at a heating rate of 3 ℃/min in the muffle furnace to 450 ℃, and preserving the heat for 5 hours;
(5) Stirring and uniformly mixing 1000g of the pre-lithiated hard carbon/silicon carbon composite material obtained in the step (4), 10g of 1-butyl-3-methylimidazolium dinitrile amine salt ionic liquid, 10g of calcium phosphate, 50g of polystyrene, 50g of polymethyl methacrylate and 50g of polyaniline particles by using absolute ethyl alcohol;
(6) And (3) uniformly mixing 1000g of the black nitrogen-phosphorus doped pre-lithiated hard carbon/silicon-carbon composite material obtained in the step (5), 5g of tungsten oxide, 5g of copper oxide and 5g of potassium phosphate in a high-speed mixer.
Example 4
Basically the same as example 1, except that:
(1) Multiwalled carbon nanotubes (5 nm inside diameter, tube length >80 μm), n-butyl chloride in example 1 was replaced with an equal amount of chlorotoluene;
(2) The biomass material is 500 g of walnut green husk and 500 g of starch;
(3) Stirring 1000g of the hard carbon precursor obtained in the step (2) and 300g of silica (99.0%) by using absolute ethyl alcohol, uniformly mixing, drying, mechanically crushing, sieving by using a 50-mesh sieve, placing in a muffle furnace, heating to 1050 ℃ at a muffle furnace heating rate of 5 ℃/min under a nitrogen atmosphere, and keeping the temperature for 5 hours;
(4) Uniformly mixing 1000g of the hard carbon/silicon carbon composite material obtained in the step (3) and 200g of the carbon nano tube filled with n-butyl lithium obtained in the step (1) in a nitrogen atmosphere;
(5) Stirring and uniformly mixing 1000g of the pre-lithiated hard carbon/silicon carbon composite material obtained in the step (4), 15g of pyridine, 10g of ammonium monohydrogen phosphate, 100g of polymethyl methacrylate and 100g of polyaniline particles by using absolute ethyl alcohol;
(6) And (3) uniformly mixing 1000g of the black nitrogen-phosphorus doped pre-lithiated hard carbon/silicon-carbon composite material obtained in the step (5), 5g of iron oxide, 3g of niobium oxide and 4g of potassium phosphate in a high-speed mixer.
Example 5
Basically the same as example 1, except that:
(1) The n-butyl chloride in example 1 was replaced with an equal amount of ethyl chloride;
(2) The biomass material is 5000g of wood and 5000g of wheat straw;
(3) Uniformly stirring and mixing 1000g of hard carbon precursor and 250g of silicon monoxide (99.0%) by using absolute ethyl alcohol, drying, mechanically crushing, sieving by using a 50-mesh sieve, placing in a muffle furnace, heating to 1250 ℃ at the muffle furnace heating rate of 5 ℃/min, and keeping the temperature for 5h;
(5) Stirring and uniformly mixing 1000g of the pre-lithiated hard carbon/silicon carbon composite material obtained in the step (4), 10g of pyrrole, 10g of ammonium phosphate, 100g of polyvinyl alcohol and 100g of asphalt particles by using absolute ethyl alcohol;
(6) And (3) uniformly mixing 1000g of the black nitrogen-phosphorus doped pre-lithiated hard carbon/silicon-carbon composite material obtained in the step (5), 2g of titanium oxide, 2g of niobium oxide, 2g of yttrium oxide and 5g of zirconium phosphate in a high-speed mixer.
Example 6
Basically the same as example 1, except that: step (6) is omitted.
Comparative example 1
(1) Cleaning 2000g of walnut green seedcase, drying, carbonizing at 400 ℃ in nitrogen atmosphere, mechanically crushing, and sieving with a 100-mesh sieve to prepare 1140g of hard carbon precursor;
(2) Uniformly mixing a hard carbon precursor and n-butyllithium in a nitrogen atmosphere, placing the mixture in a muffle furnace, heating the mixture in the nitrogen atmosphere at a heating rate of 3 ℃/min to 400 ℃, preserving the heat for 5h, naturally cooling the mixture to room temperature, mechanically crushing the mixture, and sieving the crushed mixture with a 100-mesh sieve to prepare a pre-lithiated hard carbon material;
(3) And (2) uniformly mixing 1000g of the pre-lithiated hard carbon material, 5g of alumina and 5g of lithium phosphate in a high-speed mixer, heating to 500 ℃ at a muffle furnace heating rate of 3 ℃/min, keeping the temperature for 8 hours, naturally cooling to room temperature, mechanically crushing, and sieving with a 400-mesh sieve to obtain the hard carbon composite material.
Comparative example 2
Basically the same as in example 1, except that: and (4) not including the step (1) and the step (4), in the step (5), uniformly stirring and mixing the black hard carbon/silicon carbon composite material, the ethylenediamine, the phosphorus pentoxide and the phenolic resin particles by using absolute ethyl alcohol.
Comparative example 3
Basically the same as example 1, except that: the step (1) was not included, and the carbon nanotubes filled with n-butyllithium in the step (4) of example 1 were replaced with n-butyllithium.
Comparative example 4
Basically the same as example 1, except that: omitting step (3), and step (4) mixing 1000g of the hard carbon composite material obtained in step (2) and 50g of the n-butyllithium-filled carbon nanotubes obtained in step (1) uniformly under a nitrogen atmosphere.
Comparative example 5
Basically the same as in example 1, except that: step (5) is omitted.
Comparative example 6
Basically the same as example 1, except that: in the step (5), the ethylenediamine and the phenolic resin particles are not added.
Button cell test
The modified hard carbon silicon carbon composite material prepared in each embodiment and each comparative example, the conductive agent Super P and the binder PVDF (HSV 900) are mixed according to the mass ratio of 90:2:8, dissolving in N-methyl pyrrolidone, and stirring for 15 hours by using a magnetic stirrer under the protection of argon in a glove box to prepare slurry required by electricity deduction; the coating machine is an MSK-AFA-III automatic coating dryer of Shenzhen Kejing Zhi Daji science and technology Limited, the coating gap is 25 μm, the speed is 5cm/min, the slurry is uniformly coated on a shiny side copper foil with the thickness of 9 μm and the purity of 99.8% produced by Meixian Jinxiang copper foil Limited, vacuum drying is carried out for 12h at the temperature of 120 ℃, and then an electrode slice with the diameter of about 16mm is punched by a Shenzhen Kejing MSK-T06 button cell punching machine to be used as a positive electrode; the negative electrode is a high-purity lithium sheet with the diameter of 15.8mm and the purity of 99.99 percent, the diaphragm is an American ENTEK LP16 PE diaphragm with the thickness of 16 mu m, the electrolyte is DMC: EMC with the mass ratio of 60 6 Electrical performance tests were performed on a CT2001A tester of wuhan blue electronics ltd, and the gram capacity and the first coulombic efficiency are shown in table 1;
TABLE 1
Figure BDA0003848564230000221
Figure BDA0003848564230000231
As can be seen from table 1, the modified hard carbon silicon carbon composite material prepared in the example has higher first coulombic efficiency and gram capacity when used as a negative electrode material than the comparative example.
The circulating capacity retention rate of the button cell prepared from the modified hard carbon-silicon-carbon composite material prepared in the embodiment 1 at 45 ℃ is shown in fig. 5, and the 50-turn capacity retention rate reaches 95.57%;
the retention rate of the cycling capacity of the button cell prepared from the modified hard carbon-silicon-carbon composite material prepared in the embodiment 2 at 45 ℃ is shown in fig. 6, and the retention rate of the capacity of 50 circles reaches 96.27%.
Thin film battery testing
The positive electrode material was prepared as active material NCM523: conductive agent: binder (mass ratio 96; negative electrode materials modified hard carbon silicon carbon composite materials prepared according to the examples and comparative examples: conductive agent: the binder (mass ratio of 92;
the curve of the capacity retention rate of the prepared thin film battery at 45 ℃ and 0.7C charge/1C discharge and 0.7C charge/0.2C discharge every 25 circles is shown in figure 7, wherein the abscissa is the number of cycles and the ordinate is the capacity retention rate; as can be seen from fig. 7, compared to the comparative example, the capacity retention rate was higher and the cycle performance was better when the examples were cycled at high temperature; while comparative examples 2 and 5 had poorer cycle performance than the other comparative examples; and comparative example 6 also had poorer cycle performance than the other comparative examples.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, which is convenient for specific and detailed understanding of the technical solutions of the present invention, but the present invention should not be construed as being limited to the scope of the invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. It should be understood that the technical solutions provided by the present invention, which are obtained by logical analysis, reasoning or limited experiments, are within the scope of the present invention as set forth in the appended claims. Therefore, the protection scope of the present invention should be subject to the content of the appended claims, and the description and the drawings can be used for explaining the content of the claims.

Claims (17)

1. The preparation method of the modified hard carbon-silicon-carbon composite material is characterized by comprising the following steps:
mixing the hard carbon precursor with the silicon monoxide to carry out first calcination to prepare a hard carbon-silicon-carbon composite material;
mixing the hard carbon-silicon-carbon composite material with carbon nano tubes filled with organic lithium compounds for secondary calcination to prepare a pre-lithiated hard carbon-silicon-carbon composite material;
and mixing the pre-lithiated hard carbon-silicon-carbon composite material with a nitrogen source, a phosphorus source and an organic polymer for third calcination.
2. The method of claim 1, wherein the preparing of the hard carbon precursor comprises the steps of:
and sequentially carrying out carbonization treatment and crushing treatment on the biomass material to prepare the hard carbon precursor.
3. The method of claim 2, wherein the biomass material is selected from at least one of green walnut hulls, citrus, peanut shells, coconut shells, starch, sugar cane, corn, sweet potato, seaweed, wheat straw, wood, and nut shells.
4. The method according to claim 1, wherein the mass ratio of the hard carbon precursor to the silicon monoxide is (3-100) to (0.01-30).
5. The method of any one of claims 1 to 4, wherein the preparation of the carbon nanotubes filled with the organolithium compound comprises the steps of:
mixing and refluxing the carbon nano tube, the organic lithium compound and the organic solvent.
6. The method of claim 5, wherein the carbon nanotubes have a diameter of 3nm to 100nm.
7. The method according to any one of claims 1 to 4 and 6, wherein the mass ratio of the hard carbon-silicon-carbon composite material to the carbon nanotubes filled with the organolithium compound is (2-100) to (0.01-20).
8. The method of any one of claims 1-4 and 6, wherein the mass ratio of the pre-lithiated hard carbon silicon carbon composite material, the nitrogen source, the phosphorus source and the organic polymer is (2-100): 0.1-20): 0.2-50.
9. The method of claim 8, wherein the nitrogen source is selected from at least one of ammonia, ethylenediamine, propylenediamine, butylenediamine, hexylenediamine, urea, pyridine, pyrrole, nitrogen-containing ionic liquid, ammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonium carbonate, and ammonium hydrogen carbonate; the phosphorus source is selected from at least one of elemental phosphorus, phosphorus pentoxide, lithium phosphate, ammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate and calcium phosphate; the organic polymer is selected from at least one of epoxy resin, phenolic resin, polystyrene, polymethyl methacrylate, polyaniline, polyvinyl alcohol and asphalt.
10. The production method according to any one of claims 1 to 4, 6 and 9, which satisfies at least one of the following conditions (1), (2) and (3):
(1) The first calcining temperature is 500-1500 ℃, and the time is 5-40 h;
(2) The temperature of the second calcination is 200-1000 ℃, and the time is 1-20 h;
(3) The temperature of the third calcination is 300-1500 ℃, and the time is 1-15 h.
11. The method of any one of claims 1-4, 6 and 9, further comprising a step of cladding the resulting doped prelithiated hard carbon-silicon-carbon composite after the third calcination step.
12. The method of claim 11, wherein the coating treatment comprises the steps of:
and mixing the doped prelithiated hard carbon-silicon-carbon composite material and a coating agent, wherein the coating agent is selected from at least one of oxide, fluoride and phosphate, and performing fourth calcination.
13. The production method according to claim 12, wherein the oxide is at least one selected from the group consisting of titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide, iron oxide, niobium oxide, tungsten oxide, strontium oxide, copper oxide, cerium oxide, and yttrium oxide; the fluoride is selected from at least one of aluminum fluoride, zirconium fluoride, magnesium fluoride, calcium fluoride, lithium fluoride, sodium fluoride and potassium fluoride; the phosphate is selected from at least one of lithium phosphate, sodium phosphate, aluminum phosphate, zirconium phosphate, calcium phosphate and potassium phosphate.
14. The modified hard carbon silicon carbon composite material is characterized by comprising a pre-lithiated hard carbon silicon carbon composite material A and a first coating layer B arranged on the surface of the A;
a comprises uniformly dispersed lithium complexes a 1 And hard carbon silicon carbon composite material a 2 ；
a 1 The method comprises the following steps: carbon nanotubes and lithium compounds and carbon materials filled in the carbon nanotubes;
a 2 the method comprises the following steps: hard carbon, nano silicon and silicon dioxide, wherein the nano silicon and part of the silicon dioxide are dispersed in the hard carbon, and part of the silicon dioxide is coated on the surfaces of the hard carbon and nano silicon particles;
b comprises nitrogen and phosphorus doped pyrolytic carbon.
15. The modified hard carbon silicon carbon composite of claim 14, wherein the pre-lithiated hard carbon silicon carbon composite is doped with nitrogen and phosphorous elements.
16. The modified hard carbon silicon carbon composite of claim 14, wherein the surface of the first cladding layer is provided with a second cladding layer comprising at least one of an oxide, a fluoride, and a phosphate.
17. A lithium ion battery is characterized by comprising a positive electrode, a diaphragm and a negative electrode, wherein the positive electrode and the negative electrode are arranged on two sides of the diaphragm, and the negative electrode comprises the modified hard carbon silicon carbon composite material prepared by the preparation method of the modified hard carbon silicon carbon composite material according to any one of claims 1 to 13 or the modified hard carbon silicon carbon composite material according to any one of claims 14 to 16.
CN202211130833.0A 2022-09-16 2022-09-16 Modified hard carbon silicon carbon composite material, preparation method and application thereof, and lithium ion battery Pending CN115360339A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116119645A (en) * 2022-12-27 2023-05-16 浙江大学 Preparation method of modified porous hard carbon material, product and application thereof
CN117069093A (en) * 2023-09-15 2023-11-17 福建省鑫森炭业股份有限公司 Preparation method of hard carbon anode material
CN117069093B (en) * 2023-09-15 2024-06-07 福建省鑫森炭业股份有限公司 Preparation method of hard carbon anode material

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116119645A (en) * 2022-12-27 2023-05-16 浙江大学 Preparation method of modified porous hard carbon material, product and application thereof
CN116119645B (en) * 2022-12-27 2023-08-18 浙江大学 Preparation method of modified porous hard carbon material, product and application thereof
CN117069093A (en) * 2023-09-15 2023-11-17 福建省鑫森炭业股份有限公司 Preparation method of hard carbon anode material
CN117069093B (en) * 2023-09-15 2024-06-07 福建省鑫森炭业股份有限公司 Preparation method of hard carbon anode material

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