WO2017177970A1 - 一种包覆剂、负极材料、锂离子电池及其制备方法 - Google Patents

一种包覆剂、负极材料、锂离子电池及其制备方法 Download PDF

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WO2017177970A1
WO2017177970A1 PCT/CN2017/080594 CN2017080594W WO2017177970A1 WO 2017177970 A1 WO2017177970 A1 WO 2017177970A1 CN 2017080594 W CN2017080594 W CN 2017080594W WO 2017177970 A1 WO2017177970 A1 WO 2017177970A1
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graphene
coating agent
agent
negative electrode
electrode material
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PCT/CN2017/080594
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English (en)
French (fr)
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张金柱
刘顶
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济南圣泉集团股份有限公司
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Publication of WO2017177970A1 publication Critical patent/WO2017177970A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the invention relates to the technical field of electrode materials, in particular to a coating agent, a negative electrode material, a lithium ion battery and a preparation method thereof.
  • a lithium ion battery is a general term for a battery in which a lithium ion intercalation compound is used as a positive electrode material, and a lithium-containing compound is used as a positive electrode, and no lithium metal exists, and only lithium ions are present.
  • the charging and discharging process of a lithium ion battery is a process of intercalating and deintercalating lithium ions. In the process of intercalation and deintercalation of lithium ions, concomitant insertion and deintercalation of equivalent electrons with lithium ions are accompanied.
  • graphite is an ideal material. Graphite has good electrical conductivity, high crystallinity, low cost, high bulk density and high theoretical lithium intercalation capacity. It is an important part of the current lithium ion battery anode material. However, it has some disadvantages, such as poor compatibility with the electrolyte, low reversible capacity for the first charge and discharge, unsuitable for large current charge and discharge, and poor cycle performance.
  • graphite has been modified by various methods.
  • a common modification method is to use a carbon precursor such as asphalt or a resin as a coating or a coating agent to be mixed into a negative electrode material and then carbonized. After the above modification, the capacitance and cycle number of the graphite negative electrode were improved, but the improvement was not significant, and the market significance was not significant.
  • An object of the present invention is to provide a coating agent capable of efficiently increasing the capacity and the number of cycles of a negative electrode of a lithium ion battery.
  • Another object of the present invention is to provide a negative electrode material which has the advantages of high capacity, high number of cycles, stable performance, and the like.
  • Another object of the present invention is to provide a method for preparing a negative electrode material, which has various preparation methods, and has the advantages of simple process, strong controllability, high production efficiency, and the like.
  • a further object of the present invention is to provide a lithium ion battery, which has the advantages of high capacity, high number of cycles, stable performance, and the like, and has a broader application prospect.
  • the present invention provides the following technical solutions:
  • a coating agent comprising: graphene, a water-insoluble carbon precursor, and a dispersing agent; and the dispersing agent is one or more of an aminosilane, an epoxysilane, and a polyvinyl alcohol. That is, the dispersing agent is selected from one or more selected from the group consisting of aminosilanes, epoxysilanes, and polyvinyl alcohols. a group consisting of aminosilane, epoxysilane, and polyvinyl alcohol The group comprising any one of an aminosilane, an epoxysilane, and a polyvinyl alcohol further includes a group consisting of at least two of an aminosilane, an epoxysilane, and a polyvinyl alcohol.
  • the coating agent is mainly used for the modification of the negative electrode of a lithium ion battery, and may also be used in other unknown fields.
  • the coating agent mainly adds a dispersant to solve the problem of dispersion of graphene and carbon precursor, thereby further increasing the capacity and cycle number of the electrode material.
  • the present invention selects a water-insoluble carbon precursor and is combined with a dispersing agent such as aminosilane, epoxysilane or polyvinyl alcohol to solve the problem.
  • a dispersing agent such as aminosilane, epoxysilane or polyvinyl alcohol
  • the modifier of the present invention when used in the negative electrode of a lithium ion battery, reduces the irreversible capacity of the negative electrode by more than 5% compared with the modifier without the addition of the dispersant; and graphite without adding any modifier Compared with the negative electrode, the irreversible capacity is reduced by 10% or more, and the cycle life and stability are improved by 30% or more.
  • the graphene of the present invention comprises a graphene nanosheet layer and graphene, and further the graphene further comprises a biomass graphene nanosheet layer and biomass graphene.
  • the graphene of the present invention can be obtained by different preparation methods, such as mechanical stripping method, epitaxial growth method, chemical vapor deposition method, graphite redox method, hydrothermal carbonization method for biomass resources, and prior art.
  • Graphene prepared by other methods are difficult to achieve large-scale preparation of graphene in a strictly theoretical sense.
  • some of the graphenes prepared by the prior art may have certain impurity elements, other allotropes of carbon elements or layers.
  • the layer or even the multilayer graphene structure (for example, 3 layers, 5 layers, 10 layers, 20 layers, etc.), the graphene utilized in the present invention also includes the above-mentioned non-strict theoretical graphene.
  • the graphene is prepared by any one of a mechanical stripping method, an epitaxial growth method, a chemical vapor deposition method, a graphite redox method, and a biomass resource hydrothermal carbonization method.
  • the graphene nanosheet layer can adopt the process of Jinan Shengquan Company, and the porous biomass graphene composite with excellent conductive properties is obtained by the steps of hydrolysis, catalytic treatment and heat treatment with the agricultural and forestry waste as the main raw material, and its main feature is contained.
  • the number of graphene layers is between 1 and 10 layers, and the content of non-carbon non-oxygen elements is from 0.5% by weight to 6% by weight.
  • the above coating agent can be further improved:
  • the carbon precursor is preferably one or more selected from the group consisting of a phenol resin, a urea resin, a furan resin, an epoxy resin, and a pitch.
  • the group consisting of a phenol resin, a urea resin, a furan resin, an epoxy resin, and an asphalt includes a group consisting of any one of a phenol resin, a urea resin, a furan resin, an epoxy resin, and a pitch, and further includes a phenol resin and a urea resin. a group consisting of at least two of furan resin, epoxy resin, and asphalt.
  • the amorphous structure formed by carbonization of the above carbon precursor is rich, which is more conducive to the intercalation and deintercalation of lithium ions, and also reduces the consumption of lithium ions when the SEI film is formed during the first charging.
  • the above resin is further selected from a thermosetting resin, and a medium-high molecular weight resin is further selected, and the pitch is preferably a thermosetting pitch.
  • the graphene accounts for 0.1-5% by weight of the total amount of the coating agent, and preferably, the graphene accounts for 0.5-3% by weight of the total amount of the coating agent, and further preferably, The graphene accounts for 1-2% by weight of the total amount of the coating agent; the dispersing agent accounts for 0.05-0.5% by weight of the total amount of the coating agent, preferably, by weight, the dispersion The agent accounts for 0.05-0.3% of the total amount of the coating agent. Further preferably, the dispersing agent accounts for 0.05-0.1% by weight of the total amount of the coating agent.
  • the graphene accounts for 0.1-5% by weight of the total amount of the coating agent, and the dispersing agent accounts for 0.05-0.1% of the total amount of the coating agent.
  • the graphene accounts for 0.1-5% by weight of the total amount of the coating agent; and the dispersing agent accounts for 0.05-0.5% of the total amount of the coating agent.
  • the ratio of each raw material has an important influence on the modification effect.
  • the dispersion is uniform, and the carbonization effect is good, which is more conducive to improving the capacity and life of the battery.
  • the above coating agent further includes a curing agent for the carbon precursor.
  • a curing agent facilitates the shaping of the carbon precursor.
  • the type and amount of the curing agent are selected according to the carbon precursor.
  • the available curing agent is hexamethylenetetramine, 3- Diethylaminopropylamine, trimethylhexamethylenediamine, and dihexyltriamine.
  • the curing agent is one or more selected from the group consisting of hexamethylenetetramine, 3-diethylaminopropylamine, trimethylhexamethylenediamine, and dihexyltriamine.
  • the group consisting of hexamethylenetetramine, 3-diethylaminopropylamine, trimethylhexamethylenediamine, and dihexyltriamine includes hexamethylenetetramine, 3-diethylaminopropylamine, a group consisting of any one of trimethylhexamethylenediamine and dihexyltriamine, further comprising hexamethylenetetramine, 3-diethylaminopropylamine, trimethylhexamethylenediamine, and A group consisting of at least two of dihexyltriamine.
  • the aminosilane and the epoxysilane each mean any silane containing an amino group or an epoxy group, for example, an epoxy trimethoxysilane coupling agent. Further, it is a silane coupling agent 3-ureidopropyltriethoxysilane or the like.
  • the epoxysilane is an epoxy trimethoxysilane coupling agent.
  • the epoxysilane is a silane coupling agent 3-ureidopropyltriethoxysilane.
  • the present invention provides a negative electrode material mainly made of graphite and a coating agent as described above.
  • the negative electrode material adopts common graphite as an active material, and in combination with the coating agent of the invention, it has higher capacity and cycle times than the conventional negative electrode material.
  • the anode material is currently mainly used for lithium ion batteries, but it is also possible to use batteries of other unknown types.
  • useful cathode materials are lithium manganate, lithium cobaltate or lithium iron phosphate.
  • the above negative electrode material can be further improved, for example:
  • the ratio of the coating agent and the graphite is from 3 to 15:85 to 97 by weight.
  • the above ratio of the negative electrode can fully exert the modification effect of the coating agent of the present invention, preferably 5-10:90-95. Go further 5-8:90-93. Of course, if you consider other factors such as cost and potential, you can also use a ratio outside the range.
  • the coating agent of the present invention can be packaged separately for each raw material, and can be mixed now. It can also be directly mixed and stored, which is mainly determined according to storage, transportation and the like.
  • mixed with graphite to form a negative electrode material one of the following methods may be employed:
  • Method 1 dissolving and mixing the graphene, the carbon precursor, the dispersing agent and the graphite in a solvent, and then drying and carbonizing;
  • Method 2 dissolving and mixing the graphene, the carbon precursor and the dispersing agent in a solvent, drying and mixing with graphite, and then carbonizing;
  • the curing agent when the curing agent is contained in the coating agent, the curing agent is further added when the graphene is dissolved in a solvent in the first mode and the second mode, and before the carbonization The curing reaction is carried out.
  • Both of the above methods belong to the solution method, and the difference between the two is that the drying timing is different, that is, the drying can be carried out either before the addition of graphite or after the addition of graphite.
  • the advantage of these two methods is that the equipment used is simple, and the key point is the mixing step to ensure that the components are evenly dispersed.
  • Mixing methods can be used in a variety of ways, such as ball milling, ball milling and dissolving can be carried out simultaneously, the ball milling time is generally 1-4h, which is subject to mixing.
  • the process of dissolving and mixing may be stirred while feeding, or separately, and then mixed together.
  • drying methods generally depending on the type of solvent, and available methods include heating and evaporation.
  • the timing of the curing reaction is before the carbonization reaction, and in the first mode, it may be after drying, after mixing, and before drying; in the second mode, it may be before or after mixing the graphite. After drying, it may also be after mixing the graphite and before drying.
  • the above negative electrode material may also adopt the following preparation method:
  • the graphene, the carbon precursor, and the dispersing agent are heated and kneaded, cooled, and then added to the graphite to be mixed, and obtained by carbonization;
  • the curing agent is contained in the coating agent, the curing agent is further added after the cooling, and a curing reaction is also performed before the carbonization.
  • This method belongs to the melting method and has the advantage of high production efficiency.
  • the kneading described therein can employ various devices such as a rheometer and the like. It is preferred to premix all the raw materials before the kneading.
  • the conditions for kneading the graphene, the carbon precursor, and the dispersing agent were as follows: mixing to a torque balance at 150 ° C with a rheometer.
  • the carbonization according to the present invention is further carried out at 900 ° C to 1200 ° C.
  • the curing reaction according to the present invention is mainly determined according to the curing agent and the type of the resin. Usually, the curing reaction is carried out by gradient heating, and the phenolic resin is taken as an example.
  • the curing conditions are: 120-130 ° C for 60 minutes, 140-150 ° C for 60 minutes or so. , 160-170 ° C for about 30 minutes.
  • the present invention also provides a lithium ion battery, the negative electrode of which is mainly made of the negative electrode material described above.
  • the lithium ion battery has higher capacity, more cycle times, longer service life, and more stable power storage performance than the conventional lithium ion battery.
  • the present invention has the following technical effects:
  • the dispersing effect of the coating agent is good, and the performance of the electrode material such as capacitance, life and stability can be improved to a greater extent.
  • a negative electrode material and a battery having high capacity, high number of cycles, and stable performance are provided.
  • the treated wheat straw is cooked using an organic acid solution of formic acid and acetic acid having a total acid concentration of 80% by weight, and the quality of acetic acid and formic acid in the organic acid solution of the present embodiment
  • the ratio is 1:12, and 1 wt% of hydrogen peroxide (H 2 O 2 ), which is the raw material of the wheat straw, is added as a catalyst before the addition of the raw materials, and the reaction temperature is controlled at 120 ° C for 30 min, and the solid-liquid mass ratio is 1:10.
  • H 2 O 2 hydrogen peroxide
  • the solid obtained by the first solid-liquid separation is added to an organic acid solution having a total acid concentration of 75 wt% of formic acid and acetic acid for acid washing, wherein the total acid concentration of 75 wt% of the organic acid solution is added to the wheat straw.
  • the rod raw material 8wt% hydrogen peroxide (H 2 O 2 ) as a catalyst and the mass ratio of acetic acid to formic acid is 1:12, the control temperature is 90 ° C, the washing time is 1 h, the solid-liquid mass ratio is 1:9, and the reaction is carried out.
  • the liquid is subjected to a second solid-liquid separation;
  • step (3) collecting the liquid obtained by the first and second solid-liquid separation, performing high-temperature and high-pressure evaporation at 120 ° C, 301 kPa until evaporation to dryness, and condensing the obtained formic acid and acetic acid vapor back to the reaction kettle of the step (1). Used as a cooking liquor for the cooking of step (1);
  • step (5) collecting the liquid obtained by the third solid-liquid separation, performing water and acid distillation, and returning the obtained mixed acid solution to the reaction vessel of the step (1) for use as a cooking liquid for the cooking of the step (1).
  • Water is used in step (5) to act as water for washing;
  • the precursor was heated to 170 ° C at a rate of 3 ° C / min, kept for 2 h, then programmed to 400 ° C, held for 3 h, then heated to 1200 ° C, after 3 h to obtain a crude product;
  • the heating rate of the heating is 15 ° C / min;
  • the method of the embodiment 10 of the publication No. CN104724696A is specifically: collecting the straw, cutting it into small pieces after being cleaned, immersing in an ethanol solution, stirring at a constant speed of 100 r/min for 5 hours; then transferring the solution to In the high-speed centrifuge, the rotation speed is set to 3000r/min, and the centrifugation time is 20 minutes. After the end, the lower layer is taken. Under normal temperature and pressure, the sample was placed in a cell culture dish with a diameter of 15 cm, placed at the air inlet, and the flow parameters were adjusted.
  • the wind speed was set to 6 m/s, the air volume was 1400 m 3 /h, and the ventilation state was maintained for 12 hours;
  • the furnace is heated to 1300 ° C, and is protected by inert gas for 30 minutes.
  • the dried sample is placed in a tube furnace and heated for 5 hours. After cooling to room temperature, biomass graphene with obvious separation is obtained. It is graphene B.
  • step (3) The three-necked flask of the above step (2) was transferred to an oil bath, heated to 35 ° C, stirred for 2 hours, stirring was continued, and a mixed solution of 30 wt% hydrogen peroxide and deionized water was added in an amount of 1:15 by volume. ; suction filtration, 4mL respectively Dilute hydrochloric acid and deionized water with a mass fraction of 10% are washed once, centrifuged, and dried to obtain first-oxidized graphene oxide;
  • the sol- phenolic resin PF9503 was dissolved in ethanol, and then the silane coupling agents 3-ureidopropyltriethoxysilane and trimethylhexamethylenediamine were added.
  • the mixture was ball milled for 2 hours.
  • Graphene A was gradually added to the ball milling system in portions and ball milling was maintained for 2 hours.
  • the graphene content was 1%
  • the silane content was about 0.05%
  • the amount of trimethylhexamethylenediamine added was calculated according to the actual hydroxyl value of the phenol resin.
  • the spherical graphite powder was added to the above system for ball milling, and the solid content of graphite in the total system was 85%.
  • the complex was taken out and the ethanol was evaporated to dryness.
  • the resultant was gradually heat-cured at a temperature gradient of 120 ° C for 60 minutes, 140 ° C for 60 minutes, and 160 ° C for 30 minutes.
  • the dried solid was subjected to heat treatment, N 2 was passed as a shielding gas, and then carbonized at a temperature of 5 ° C / min to 800 ° C. After 2 hours of heat preservation, it was cooled to room temperature to obtain a graphene/amorphous carbon-coated graphite anode material.
  • Example 2-6 The difference between Examples 2-6 and Example 1 lies in the compounding stage of Step 1, and the amount of graphene added is 0.1%, 0.5%, 2%, 3%, 5%, respectively.
  • the ginseng phenolic resin PF9503, the silane coupling agent 3-ureidopropyltriethoxysilane, and graphene A were mixed.
  • the mixture was mixed well using a high mixer.
  • the graphene A content is 1%, and the silane content is about 0.1%.
  • the mixture was kneaded using a rheometer, mixed at 150 ° C until torque balance, and then taken out for cooling.
  • the above powder was added with hexamethylenetetramine, and the amount of hexamethylenetetramine added was calculated based on the actual hydroxyl value of the phenol resin. Subsequently, graphite powder was added, and the content of graphite in the total system accounted for 90%.
  • the mixture was mixed for 2 hours using a high mixer. After removal, the mixture was gradually heat-cured at a temperature gradient of 130 ° C for 120 minutes, 150 ° C for 60 minutes, and 170 ° C for 30 minutes.
  • the dried solid was subjected to heat treatment, N 2 was passed as a shielding gas, and then heated to 900 ° C at 5 ° C / min for carbonization. After 2 hours of heat preservation, it was cooled to room temperature to obtain a graphene/amorphous carbon-coated graphite anode material.
  • Example 8-10 The difference between Examples 8-10 and Example 7 is that in the coating stage of Step 2, the content of graphite in the total system accounts for 93%, 95%, and 97%, respectively.
  • thermosetting urea-formaldehyde resin WPLQ-5115, a silane coupling agent 3-ureidotriethoxysilane, and graphene A were mixed.
  • the mixture was mixed well using a high mixer.
  • the graphene A content was 1%, and the coupling agent content was 0.5%.
  • the mixture was kneaded using a rheometer, mixed at 150 ° C until torque balance, and then taken out for cooling.
  • Zinc sulfate (which may also be replaced by diethyl oxalate) is added to the above powder, and the amount of the curing agent added is calculated based on the actual amount of the urea-formaldehyde resin. Subsequently, graphite powder was added, and the solid content of graphite in the total system was 95%. The mixture was mixed for 2 hours using a high mixer. After removal, the mixture was gradually heat-cured at a temperature gradient of 130 ° C for 120 minutes, 150 ° C for 60 minutes, and 170 ° C for 30 minutes.
  • the dried solid was subjected to heat treatment, N 2 was passed as a shielding gas, and then heated to 900 ° C at 5 ° C / min for carbonization. After 2 hours of heat preservation, it was cooled to room temperature to obtain a graphene/amorphous carbon-coated graphite anode material.
  • the St. Spring furan resin SH263, the silane coupling agent 3-ureidopropyltriethoxysilane, and graphene A were mixed.
  • the mixture was mixed well using a high mixer.
  • the graphene A content was 1%, and the coupling agent content was 0.3%.
  • the mixture was kneaded using a rheometer, mixed at 150 ° C until torque balance, and then taken out for cooling.
  • the curing agent is added in an amount according to the actual amount of the furan resin. Count. Subsequently, graphite powder was added, and the solid content of graphite in the total system was 95%. The mixture was mixed for 2 hours using a high mixer. After removal, the mixture was gradually heat-cured at a temperature gradient of 130 ° C for 120 minutes, 150 ° C for 60 minutes, and 170 ° C for 30 minutes.
  • the dried solid was subjected to heat treatment, N 2 was passed as a shielding gas, and then heated to 900 ° C at 5 ° C / min for carbonization. After 2 hours of heat preservation, it was cooled to room temperature to obtain a graphene/amorphous carbon-coated graphite anode material.
  • the high molecular weight Shengquan epoxy resin SQPN-631, the silane coupling agent 3-ureidopropyltriethoxysilane and graphene A were mixed.
  • the mixture was mixed well using a high mixer.
  • the graphene A content was 1%, and the coupling agent content was 0.3%.
  • the mixture was kneaded using a rheometer, mixed at 150 ° C until torque balance, and then taken out for cooling.
  • Diethylenetriamine (which may also be replaced by ethylenediamine) is added to the above powder, and the amount of the curing agent added is calculated based on the actual hydroxyl value of the epoxy resin. Subsequently, graphite powder was added, and the solid content of graphite in the total system was 95%. The mixture was mixed for 2 hours using a high mixer. After removal, the mixture was gradually heat-cured at a temperature gradient of 130 ° C for 120 minutes, 150 ° C for 60 minutes, and 170 ° C for 30 minutes.
  • the dried solid was subjected to heat treatment, N 2 was passed as a shielding gas, and then heated to 900 ° C at 5 ° C / min for carbonization. After 2 hours of heat preservation, it was cooled to room temperature to obtain a graphene/amorphous carbon-coated graphite anode material.
  • thermosetting epoxy pitch hc-225 The thermosetting epoxy pitch hc-225, the silane coupling agent 3-ureidopropyltriethoxysilane, and graphene C were mixed.
  • the mixture was mixed well using a high mixer.
  • the graphene A content was 1%, and the coupling agent content was 0.3%.
  • the mixture was kneaded using a rheometer, mixed at 150 ° C until torque balance, and then taken out for cooling.
  • the graphite powder in the above powder and graphite have a solid content of 95% in the total system.
  • the mixture was mixed for 2 hours using a high mixer.
  • the mixed solid was subjected to heat treatment, N 2 was supplied as a shielding gas, and then carbonized at a temperature of 5 ° C / min to 900 ° C. After 2 hours of heat preservation, it was cooled to room temperature to obtain a graphene/amorphous carbon-coated graphite anode material.
  • Examples 15-16 differed in that graphene A was replaced with graphene B and graphene C, respectively.

Abstract

一种包覆剂、负极材料、锂离子电池及其制备方法。包覆剂包括：石墨烯，非水溶性的碳前驱体，分散剂；所述分散剂为氨基硅烷、环氧基硅烷、聚乙烯醇中的一种或多种。负极材料主要由石墨和该包覆剂制成。包覆剂主要采用石墨烯与无定形碳所构成的微电容理论，提高了锂离子电池的电容量和循环次数。

Description

一种包覆剂、负极材料、锂离子电池及其制备方法
本申请要求于2016年04月14日提交中国专利局、申请号为CN201610231149.X、发明名称为“一种包覆剂、负极材料、锂离子电池及其制备方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及电极材料技术领域，尤其是涉及一种包覆剂、负极材料、锂离子电池及其制备方法。
背景技术
锂离子电池是指以锂离子嵌入化合物为正极材料电池的总称，其以含锂的化合物作正极，没有金属锂存在，只有锂离子。锂离子电池的充放电过程，就是锂离子的嵌入和脱嵌过程。在锂离子的嵌入和脱嵌过程中，同时伴随着与锂离子等当量电子的嵌入和脱嵌。
对于锂离子电池负极来说，石墨是一种较为理想的材料。石墨具有良好的导电性，结晶度高，成本低，堆积密度高，理论嵌锂容量高，是目前锂离子电池负极材料的重要部分。但是，其存在一些缺点，如与电解液相容性差，首次充放电可逆容量低，不适合大电流充放电，循环性能差。
为了解决石墨材料的上述缺点，人们通过各种方法对石墨进行改性。常见的改性方法是以沥青、树脂等碳前驱体作为涂层或包覆剂混入负极材料中，再经过碳化。经过以上改性后，石墨负极的电容量、循环次数均有所改善，但是改善并不显著，市场意义不大。
发明内容
本发明的之一目的在于提供一种包覆剂，所述的包覆剂能够高效提高锂离子电池负极的电容量和循环次数。
本发明的另一目的在于提供一种负极材料，所述的负极材料具有电容量高，循环次数多，性能稳定等优点。
本发明的又一目的在于提供一种负极材料的制备方法，所述的制备方法有多种，均具有流程简单、可控性强、生产效率高等优点。
本发明的再一目的在于提供一种锂离子电池，所述的电池具有电容量高，循环次数多，性能稳定等优点，具有更广阔的应用前景。
为了解决以上技术问题中的至少一个，本发明提供了以下技术方案：
一种包覆剂，包括：石墨烯，非水溶性的碳前驱体，和分散剂；所述分散剂为氨基硅烷、环氧基硅烷、聚乙烯醇中的一种或多种。即所述分散剂选自由氨基硅烷、环氧基硅烷以及聚乙烯醇组成的组中的一种或多种。由氨基硅烷、环氧基硅烷以及聚乙烯醇组成的组 包括由氨基硅烷、环氧基硅烷以及聚乙烯醇中任意一者组成的组，还包括由氨基硅烷、环氧基硅烷以及聚乙烯醇中的至少两者组成的组。
该包覆剂主要用于对锂离子电池的负极改性，有也可能用于其他未知的领域。
与现有的锂离子电池负极改性材料相比，该包覆剂主要是增加了分散剂，以解决石墨烯与碳前驱体的分散问题，从而进一步提高了电极材料的容量及循环次数。
其中，碳前驱体与分散剂的相容性问题对改性效果非常重要，本发明选用了非水溶性的碳前驱体，并搭配氨基硅烷、环氧基硅烷、聚乙烯醇等分散剂，解决了上述问题。
经统计，用于锂离子电池的负极时，与未添加分散剂的改性剂相比，本发明的改性剂使负极的不可逆容量降低了5％以上；与未添加任何改性剂的石墨负极相比，不可逆容量降低了10％以上,循环寿命和稳定性提高30％以上。
本发明所述的石墨烯包括石墨烯纳米片层和石墨烯，进一步所述的石墨烯还包括生物质石墨烯纳米片层和生物质石墨烯。
本发明所述的石墨烯可通过不同制备方法得到，例如机械剥离法、外延生长法、化学气相沉淀法，石墨氧化还原法，还可以是通过对生物质资源水热碳化法，以及现有技术中其它方法制备的石墨烯。但是，有些方法很难实现大规模制备得到严格意义理论上的石墨烯，例如一部分现有技术制备得到的石墨烯中会存在某些杂质元素、碳元素的其它同素异形体或层数非单层甚至多层的石墨烯结构(例如3层、5层、10层、20层等)，本发明所利用的石墨烯也包括上述非严格意义理论上的石墨烯。
可选地，所述石墨烯采用机械剥离法、外延生长法、化学气相沉淀法、石墨氧化还原法以及对生物质资源水热碳化法中的任一种方法制备而成。
石墨烯纳米片层可采用济南圣泉公司工艺，以农林废弃物为主要原料，通过水解、催化处理、热处理等步骤获得具有优良导电性质的多孔生物质石墨烯复合物，其主要特征为所含石墨烯层数为1～10层之间，非碳非氧元素含量为0.5wt％～6wt％。
上述包覆剂还可以进一步改进：
进一步地，所述碳前驱体优选为选自由酚醛树脂、脲醛树脂、呋喃树脂、环氧树脂以及沥青中组成的组中的一种或多种。由酚醛树脂、脲醛树脂、呋喃树脂、环氧树脂以及沥青组成的组包括由酚醛树脂、脲醛树脂、呋喃树脂、环氧树脂以及沥青中任意一者组成的组，还包括由酚醛树脂、脲醛树脂、呋喃树脂、环氧树脂以及沥青中的至少两者组成的组。
以上碳前驱体经碳化后所形成的无定形结构丰富，更有利于锂离子的嵌入和脱嵌，也减少了首次充电时形成SEI膜时锂离子的消耗。具体地，以上树脂进一步选用热固性树脂，进一步选用中高分子量的树脂，沥青优选热固性沥青。
进一步地，按重量计，所述石墨烯占包覆剂总量的0.1-5％，优选的，按重量计，所述石墨烯占包覆剂总量的0.5-3％，进一步优选的，按重量计，所述石墨烯占包覆剂总量的1-2％；按重量计，所述分散剂占包覆剂总量的0.05-0.5％，优选的，按重量计，所述分散剂占包覆剂总量0.05-0.3％，进一步优选的，按重量计，所述分散剂占包覆剂总量0.05-0.1％。
可选地，按重量计，所述石墨烯占包覆剂总量的0.1-5％，所述分散剂占包覆剂总量的0.05-0.1％。
可选地，按重量计，所述石墨烯占包覆剂总量的0.1-5％；且所述分散剂占包覆剂总量的0.05-0.5％。
各原料的配比对改性效果有重要影响，以上述比例混合时，分散均匀，且碳化效果好，更利于提高电池的容量及寿命。
进一步地，上述包覆剂还包括用于所述碳前驱体的固化剂。
加入固化剂有利于所述碳前驱体的定形，固化剂的类型及用量根据碳前驱体来选择，例如当碳前驱体为热固性树脂时，可用的固化剂有六次甲基四胺、3-二乙胺基丙胺、三甲基六亚甲基二胺以及二己基三胺等。
可选地，所述固化剂选自由六次甲基四胺、3-二乙胺基丙胺、三甲基六亚甲基二胺以及二己基三胺中组成的组中的一种或多种。由六次甲基四胺、3-二乙胺基丙胺、三甲基六亚甲基二胺以及二己基三胺组成的组包括由六次甲基四胺、3-二乙胺基丙胺、三甲基六亚甲基二胺以及二己基三胺中任意一者组成的组，还包括由六次甲基四胺、3-二乙胺基丙胺、三甲基六亚甲基二胺以及二己基三胺中的至少两者组成的组。
进一步地，分散剂中，氨基硅烷、环氧基硅烷分别指含有氨基或环氧基的任意硅烷，例如环氧基三甲氧基硅烷偶联剂等。进一步为硅烷偶联剂3-脲丙基三乙氧基硅烷等。可选地，所述环氧基硅烷为环氧基三甲氧基硅烷偶联剂。可选地，所述环氧基硅烷为硅烷偶联剂3-脲丙基三乙氧基硅烷。
另外，本发明提供一种负极材料，主要由石墨和上文所述的包覆剂制成。
该负极材料采用常用的石墨作为活性材料，再配合本发明的包覆剂，将比传统的负极材料具有更高的电容量及循环次数。同样，目前该负极材料主要用于锂离子电池，但也有可能用于其他未知类型的电池。当用于锂离子电池时，可用的正极材料有锰酸锂、钴酸锂或磷酸铁锂等。
以上负极材料可进一步改进，例如：
进一步地，按重量计，所述包覆剂、所述石墨的配比为3-15:85-97。
相对而言，以上比例的负极能充分发挥本发明的包覆剂的改性效果，优选5-10:90-95， 更进一步5-8:90-93。当然若考虑成本、电势等其他因素时，也可以采用范围之外的配比。
另外，本发明所述的包覆剂可以各原料独立包装，现用现混；也可以直接混匀储存，这主要是根据储存、运输等要求而定。当与石墨混合制成负极材料时，可以采用以下方式中的一种：
方式一：将所述石墨烯、所述碳前驱体、所述分散剂以及所述石墨在溶剂中溶解并混匀，之后干燥、碳化即得；
方式二：将所述石墨烯、所述碳前驱体以及所述分散剂在溶剂中溶解并混匀，经过干燥后与石墨混合，再碳化即得；
其中，当所述包覆剂中含有所述固化剂时，所述方式一和所述方式二中将所述石墨烯在溶剂中溶解时还加入所述固化剂，并且在所述碳化之前还进行固化反应。
以上两种方式都属于溶液法，两者的区别是干燥时机不同，即干燥既可以在加入石墨前进行也可以在加入石墨后进行。这两种方式的优点是所用的设备简单，关键点是混匀步骤，以保证各成分互相分散均匀。混匀方式可以采用多种，例如球磨，球磨和溶解可同时进行，球磨时间一般为1-4h，以混匀为准。
溶解和混匀的过程中可以是边加料边搅拌，也可以是分别溶解，然后在混匀在一起。
干燥方法有很多种，一般视溶剂的类型而定，可用的方法有加热蒸发等。
当含有固化剂时，固化反应的时机是在碳化反应之前，而且在方式一中既可以在干燥之后，也可以是混匀之后和干燥之前；在方式二中既可以在混合石墨之前，也可以在干燥之后，也可以是混合石墨之后和干燥之前。
另外，上述负极材料还可采用以下制备方法：
将所述石墨烯、所述碳前驱体、所述分散剂加热混捏、冷却，再加入所述石墨混合，经过碳化即得；
当所述包覆剂中含有所述固化剂时，在所述冷却之后还加入所述固化剂，并且在所述碳化之前还进行固化反应。
该方法属于熔融法，其优点是生产效率高。其所述的混捏可采用多种设备，例如流变仪等。所述混捏之前优选将所有原料预先混合。
混捏所述石墨烯、所述碳前驱体以及所述分散剂的条件为：用流变仪在150℃混合至扭矩平衡。
本发明所述的碳化进一步为：在900℃-1200℃下进行。
本发明所述的固化反应主要根据固化剂及树脂类型而定，通常固化反应采用梯度加热固化,以酚醛树脂为例，固化条件为：120-130℃60分钟左右，140-150℃60分钟左右， 160-170℃30分钟左右。
除上文提供的三种制备方法外，本发明所述的负极材料也可采用其他制备方法。
本发明还提供了一种锂离子电池，所述锂离子电池的负极主要由前文所述的负极材料制成。
同上文所述，该锂离子电池比传统的锂离子电池具有更高的电容量，更多的循环次数，更长的使用寿命，更稳定的蓄电性能。
与现有技术相比，本发明具有以下技术效果：
(1)包覆剂的分散效果好，能更大程度改善电极材料的电容量、寿命、稳定性等性能。
(2)提供了电容量高，循环次数多，性能稳定的负极材料及电池。
(3)提供了制备负极材料的多种方法，为生产者提供了更多选择。
具体实施方式
下面将结合具体实施方式对本发明的技术方案进行清楚、完整地描述，但是本领域技术人员将会理解，下列所描述的实施例是本发明一部分实施例，而不是全部的实施例，仅用于说明本发明，而不应视为限制本发明的范围。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。实施例中未注明具体条件者，按照常规条件或制造商建议的条件进行。所用试剂或仪器未注明生产厂商者，均为可以通过市售购买获得的常规产品。
制备石墨烯A：
先制备纤维素：
(1)将小麦秸杆粉碎预处理后，使用总酸浓为80wt％的甲酸和乙酸的有机酸液对处理后的小麦秸杆进行蒸煮，本实施例的有机酸液中乙酸与甲酸的质量比为1:12，并在加入原料前加入占小麦秸杆原料1wt％的过氧化氢(H2O2)作为催化剂，控制反应温度120℃，反应30min，固液质量比为1:10，并将得到的反应液进行第一次固液分离；
(2)将第一次固液分离得到的固体加入总酸浓为75wt％的甲酸和乙酸的有机酸液进行酸洗涤，其中上述总酸浓为75wt％的有机酸液中加入了占小麦秸杆原料8wt％的过氧化氢(H2O2)作为催化剂且乙酸与甲酸的质量比为1:12，控制温度为90℃，洗涤时间1h，固液质量比为1:9，并将反应液进行第二次固液分离；
(3)收集第一次和第二次固液分离得到的液体，于120℃，301kPa下进行高温高压蒸发，直至蒸干，将得到的甲酸和乙酸蒸气冷凝回流至步骤(1)的反应釜中作为蒸煮液，用于步骤(1)的蒸煮；
(4)收集第二次固液分离得到的固体，并进行水洗，控制水洗温度为80℃，水洗浆浓为6wt％，并将得到的水洗浆进行第三次固液分离；
(5)收集第三次固液分离得到的液体，进行水、酸精馏，得到的混合酸液回用于步骤(1)的反应釜中作为蒸煮液用于步骤(1)的蒸煮，得到的水回用于步骤(5)作用水洗用水；
(6)收集第三次固液分离得到的固体并进行筛选得到所需的细浆纤维素。
然后以上文制备的纤维素为原料制备石墨烯：
(1)按质量比1:1混合纤维素和氯化亚铁，在150℃下搅拌进行催化处理4h，干燥至前驱体水分含量10wt％，得到前驱体；
(2)N2气氛中，以3℃/min速率将前驱体升温至170℃，保温2h，之后程序升温至400℃，保温3h，之后升温至1200℃，保温3h后得到粗品；所述程序升温的升温速率为15℃/min；
(3)55-65℃下，将粗品经过浓度为10％的氢氧化钠溶液、4wt％的盐酸酸洗后，水洗得到生物质石墨烯，记为石墨烯A。
制备石墨烯B：
采用公开号为CN104724696A的专利中实施例10的方法，具体为：收集秸秆，处理干净后剪碎成小片，浸渍在乙醇溶液中，以100r/min的转速匀速搅拌5小时；然后将溶液转移至高速离心机中，转速设置为3000r/min，离心时间为20分钟，结束后取下层碎样。常温常压下，将碎样装入直径为15cm的细胞培养皿中，置于进风口处，调节流量参数，设置风速为6m/s，风量为1400m3/h，保持通风状态12小时；管式炉升温到1300℃，通入惰性气体保护，保持30分钟；将干燥后的碎样放置于管式炉中，加热5小时，冷却到室温后，得到剥离比较明显的生物质石墨烯，记为石墨烯B。
制备石墨烯C：
采用公开号为CN105217621A的专利中实施例1的方法，具体为：
(1)在反应器内将2g石墨粉与3g连二硫酸钾、3g五氧化二磷和12mL浓硫酸的混合体系中反应，80℃水浴条件下搅拌4小时，至形成深蓝色溶液，冷却、抽滤、干燥后得到预氧化的石墨；
(2)取步骤(1)所制得的氧化石墨2g于三颈烧瓶中，在冰水浴的条件下与150mL浓硫酸溶液，逐渐加入25g的高锰酸钾，搅拌2小时；
(3)将上述步骤(2)的三颈烧瓶转入油浴，升温至35℃，搅拌2小时，继续搅拌并按照体积比例为1:15的量加入30wt％双氧水和去离子水的混合溶液；抽滤，分别用4mL 质量分数为10％的稀盐酸和去离子水清洗1次，离心，干燥后得到第一次氧化的氧化石墨烯；
(4)将步骤(3)中制备的氧化石墨烯2g再次在冰水浴的条件下与50mL的浓硫酸溶液混合于三颈烧瓶内，逐渐加入8g的KMnO4，搅拌1小时；
(5)将上述步骤(4)的三颈烧瓶转入油浴，升温至40℃，搅拌1小时，然后继续升温至90℃，搅拌1小时后，继续搅拌并按照体积比例为1:7的量加入30wt％双氧水和去离子水的混合溶液，继续搅拌6小时后冷却，抽滤，分别用4mL质量分数为10％的稀盐酸和去离子水清洗2次，离心，干燥后得到尺寸均一的氧化石墨烯，记为石墨烯C。
以下是实施例百分比均为重量百分比。
实施例1
1.复合
将圣泉酚醛树脂PF9503溶于乙醇中，再加入硅烷偶联剂3-脲丙基三乙氧基硅烷和三甲基六亚甲基二胺。将混合物进行球磨2小时。将石墨烯A逐步分批加入到球磨体系中，保持球磨2小时。最后混合物中，石墨烯含量为1％，硅烷含量约为0.05％，三甲基六亚甲基二胺加入量按照酚醛树脂实际羟基值进行计算。
2.包覆
将球形石墨粉加入到上述体系中进行球磨，石墨在总体系中固含量占85％。
球磨2小时后，将复合物取出，并将乙醇蒸干。将所得物进行逐步加热固化，温度梯度分别为:120℃ 60分钟，140℃ 60分钟，160℃ 30分钟。
3.碳化
将干燥好的固体进行热处理，通入N2作为保护气，然后以5℃/min升温至800℃进行碳化。保温2小时后冷却至室温，即得到石墨烯/无定形碳包覆的石墨负极材料。
实施例2-6
实施例2-6与实施例1区别点在于步骤1的复合阶段，石墨烯加入量分别为0.1％，0.5％，2％，3％，5％。
实施例7
1.复合
将圣泉酚醛树脂PF9503、硅烷偶联剂3-脲丙基三乙氧基硅烷和石墨烯A混合。将混合物使用高混机进行混合均匀。其中石墨烯A含量为1％，硅烷含量约为0.1％。将混合物使用流变仪进行捏合，保持150℃混合至扭矩平衡，随后取出冷却。
2.包覆
将上述粉末中加入六次甲基四胺，六次甲基四胺加入量按酚醛树脂实际羟基值进行计算。随后加入石墨粉，石墨在总体系中含量占90％。将混合物使用高混机进行混合处理2小时。取出后，将混合物进行逐步加热固化，温度梯度分别为:130℃ 120分钟，150℃ 60分钟，170℃ 30分钟。
3.碳化
将干燥好的固体进行热处理，通入N2作为保护气，然后以5℃/min升温至900℃进行碳化。保温2小时后冷却至室温，即得到石墨烯/无定形碳包覆的石墨负极材料。
实施例8-10
实施例8-10与实施例7的区别点在于步骤2的包覆阶段，石墨在总体系中含量分别占93％,95％，97％。
实施例11
1.复合
将热固性脲醛树脂WPLQ-5115、硅烷偶联剂3-脲丙基三乙氧基硅烷和石墨烯A混合。将混合物使用高混机进行混合均匀。其中石墨烯A含量为1％，偶联剂含量为0.5％。将混合物使用流变仪进行捏合，保持150℃混合至扭矩平衡，随后取出冷却。
2.包覆
将上述粉末中加入硫酸锌(也可用草酸二乙酯替代)，该固化剂加入量按脲醛树脂实际量进行计算。随后加入石墨粉，石墨在总体系中固含量占95％。将混合物使用高混机进行混合处理2小时。取出后，将混合物进行逐步加热固化，温度梯度分别为:130℃ 120分钟，150℃ 60分钟，170℃ 30分钟。
3.碳化
将干燥好的固体进行热处理，通入N2作为保护气，然后以5℃/min升温至900℃进行碳化。保温2小时后冷却至室温，即得到石墨烯/无定形碳包覆的石墨负极材料。
实施例12
1.复合
将圣泉呋喃树脂SH263、硅烷偶联剂3-脲丙基三乙氧基硅烷和石墨烯A混合。将混合物使用高混机进行混合均匀。其中石墨烯A含量为1％，偶联剂含量为0.3％。将混合物使用流变仪进行捏合，保持150℃混合至扭矩平衡，随后取出冷却。
2.包覆
将上述粉末中加入圣泉呋喃固化剂GS05，该固化剂加入量按呋喃树脂实际量进行计 算。随后加入石墨粉，石墨在总体系中固含量占95％。将混合物使用高混机进行混合处理2小时。取出后，将混合物进行逐步加热固化，温度梯度分别为:130℃ 120分钟，150℃60分钟，170℃ 30分钟。
3.碳化
将干燥好的固体进行热处理，通入N2作为保护气，然后以5℃/min升温至900℃进行碳化。保温2小时后冷却至室温，即得到石墨烯/无定形碳包覆的石墨负极材料。
实施例13
1.复合
将高分子量圣泉环氧树脂SQPN-631、硅烷偶联剂3-脲丙基三乙氧基硅烷和石墨烯A混合。将混合物使用高混机进行混合均匀。其中石墨烯A含量为1％，偶联剂含量为0.3％。将混合物使用流变仪进行捏合，保持150℃混合至扭矩平衡，随后取出冷却。
2.包覆
将上述粉末中加入二亚乙基三胺(也可用乙二胺替代)，该固化剂加入量按环氧树脂实际羟基值进行计算。随后加入石墨粉，石墨在总体系中固含量占95％。将混合物使用高混机进行混合处理2小时。取出后，将混合物进行逐步加热固化，温度梯度分别为:130℃ 120分钟，150℃ 60分钟，170℃ 30分钟。
3.碳化
将干燥好的固体进行热处理，通入N2作为保护气，然后以5℃/min升温至900℃进行碳化。保温2小时后冷却至室温，即得到石墨烯/无定形碳包覆的石墨负极材料。
实施例14
1.复合
将热固性环氧沥青hc-225、硅烷偶联剂3-脲丙基三乙氧基硅烷和石墨烯C混合。将混合物使用高混机进行混合均匀。其中石墨烯A含量为1％，偶联剂含量为0.3％。将混合物使用流变仪进行捏合，保持150℃混合至扭矩平衡，随后取出冷却。
2.包覆
将上述粉末中石墨粉，石墨在总体系中固含量占95％。将混合物使用高混机进行混合处理2小时。
3.碳化
将混合好的固体进行热处理，通入N2作为保护气，然后以5℃/min升温至900℃进行碳化。保温2小时后冷却至室温，即得到石墨烯/无定形碳包覆的石墨负极材料。
实施例15-16
与实施例7相比，实施例15-16区别点在于将石墨烯A分别替换为石墨烯B和石墨烯C。
对照组：
按照专利公开号CN104934603A《一种石墨烯掺杂与碳包覆改性石墨负极材料的制备方法》中的实施例2进行操作，得到的实验结果如表1数据。
实验
测试以上实施例所得产品的质量，并与对照组对比，实验方法同CN104934603A中的实施例2，结果如表1。
表1产品质量
Figure PCTCN2017080594-appb-000001
Figure PCTCN2017080594-appb-000002
最后应说明的是：以上各实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述各实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的范围。

Claims (18)

  1. 一种包覆剂，其特征在于，包括：石墨烯，非水溶性的碳前驱体，和分散剂；所述分散剂为氨基硅烷、环氧基硅烷、聚乙烯醇中的一种或多种。
  2. 根据权利要求1所述的包覆剂，其特征在于，所述碳前驱体选自由酚醛树脂、脲醛树脂、呋喃树脂、环氧树脂以及沥青组成的组中的一种或多种。
  3. 根据权利要求1或2所述的包覆剂，其特征在于，按重量计，所述石墨烯占所述包覆剂总量的0.1-5％，所述分散剂占所述包覆剂总量的0.05-0.1％。
  4. 根据权利要求1-3任一项所述的包覆剂，其特征在于，所述包覆剂还包括用于所述碳前驱体的固化剂；优选的，所述固化剂选自由六次甲基四胺、3-二乙胺基丙胺、三甲基六亚甲基二胺以及二己基三胺中组成的组中的一种或多种。
  5. 根据权利要求1-4任一项所述的包覆剂，其特征在于，按重量计，所述石墨烯占所述包覆剂总量的0.5-3％；优选的，按重量计，所述石墨烯占所述包覆剂总量的1-2％。
  6. 根据权利要求1-5任一项所述的包覆剂，其特征在于，按重量计，所述分散剂占包覆剂总量的0.05-0.5％，优选的，按重量计，所述分散剂占包覆剂总量的0.05-0.3％，优选的，按重量计，所述分散剂占包覆剂总量的0.05-0.1％。
  7. 根据权利要求1-6任一项所述的包覆剂，其特征在于，所述石墨烯包括石墨烯纳米片层和石墨烯；优选地，所述石墨烯包括生物质石墨烯纳米片层和生物质石墨烯。
  8. 根据权利要求1-7任一项所述的包覆剂，其特征在于，所述石墨烯采用机械剥离法、外延生长法、化学气相沉淀法、石墨氧化还原法以及对生物质资源水热碳化法中的任一种方法制备而成。
  9. 根据权利要求1-8任一项所述的包覆剂，其特征在于，所含石墨烯层数为1～10层之间，非碳非氧元素含量为0.5wt％～6wt％。
  10. 根据权利要求1-9任一项所述的包覆剂，其特征在于，所述氨基硅烷为环氧基三甲氧基硅烷偶联剂；优选的，所述氨基硅烷为硅烷偶联剂3-脲丙基三乙氧基硅烷。
  11. 一种负极材料，其特征在于，主要由石墨和权利要求1-10任一项所述的包覆剂制成。
  12. 根据权利要求11所述的负极材料，其特征在于，所述包覆剂与所述石墨的质量比为3-15:85-97，优选5-10:90-95，更优选5-8:90-93。
  13. 权利要求11或12所述的负极材料的制备方法，其特征在于，采用以下方式中的一种：
    方式一：将所述石墨烯、所述碳前驱体、所述分散剂以及所述石墨在溶剂中溶解并混匀，之后干燥、碳化即得；
    方式二：将所述石墨烯、所述碳前驱体以及所述分散剂在溶剂中溶解并混匀，经过干燥后与石墨混合，再碳化即得；
    其中，当所述包覆剂中含有所述固化剂时，所述方式一和所述方式二中将所述石墨烯在溶剂中溶解时还加入所述固化剂，并且在所述碳化之前还进行固化反应。
  14. 权利要求11-13任一项所述的负极材料的制备方法，其特征在于，包括下列步骤：
    将所述石墨烯、所述碳前驱体以及所述分散剂加热混捏、冷却，再加入所述石墨混合，经过碳化即得；
    当所述包覆剂中含有所述固化剂时，在所述冷却之后还加入所述固化剂，并且在所述碳化之前还进行固化反应。
  15. 根据权利要求11-14任一项所述的负极材料的制备方法，其特征在于，所述碳化是在900℃-1200℃下进行。
  16. 根据权利要求11-15任一项所述的负极材料的制备方法，其特征在于，混捏所述石墨烯、所述碳前驱体以及所述分散剂的条件为：用流变仪在150℃混合至扭矩平衡。
  17. 根据权利要求11-16任一项所述的负极材料的制备方法，其特征在于，所述固化反应采用梯度加热固化。
  18. 一种锂离子电池，其特征在于，所述锂离子电池的负极主要由权利要求11-17任一项所述的负极材料制成。
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WO2016032240A1 (ko) * 2014-08-26 2016-03-03 주식회사 엘지화학 이중 코팅층을 갖는 음극 활물질, 이의 제조방법 및 이를 포함하는 리튬 이차전지
CN104752696A (zh) * 2015-01-22 2015-07-01 湖州创亚动力电池材料有限公司 一种石墨烯基硅碳复合负极材料的制备方法
CN104638252A (zh) * 2015-02-13 2015-05-20 深圳市贝特瑞新能源材料股份有限公司 一种硅复合负极材料、制备方法及锂离子电池
CN104934603A (zh) * 2015-05-22 2015-09-23 田东 一种石墨烯掺杂与碳包覆改性石墨负极材料的制备方法
CN106469814A (zh) * 2016-04-14 2017-03-01 济南圣泉集团股份有限公司 一种包覆剂、负极材料、锂离子电池及其制备方法

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CN109232985B (zh) * 2018-08-17 2021-01-05 广西大学 用于沥青改性的石墨烯材料及制备方法和应用
CN112787042A (zh) * 2020-04-24 2021-05-11 深圳市劢全新材料科技有限责任公司 一种锂电池隔膜及其制备方法
CN112537766A (zh) * 2020-11-17 2021-03-23 浙江大学自贡创新中心 一种用于锂离子电池的碳氮复合负极材料的制备方法
CN114551803A (zh) * 2022-02-26 2022-05-27 宁德新能源科技有限公司 一种用于锂金属负极的三维梯度电极及其制备方法

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