WO2019223756A1 - 一种石墨材料及其制备方法和应用 - Google Patents

一种石墨材料及其制备方法和应用 Download PDF

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WO2019223756A1
WO2019223756A1 PCT/CN2019/088105 CN2019088105W WO2019223756A1 WO 2019223756 A1 WO2019223756 A1 WO 2019223756A1 CN 2019088105 W CN2019088105 W CN 2019088105W WO 2019223756 A1 WO2019223756 A1 WO 2019223756A1
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graphite
less
ratio
graphite material
average diameter
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French (fr)
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杨东宁
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深圳三匚科技有限公司
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/184—Preparation
    • C01B32/19—Preparation by exfoliation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C01B32/21—After-treatment
    • C01B32/22—Intercalation
    • C01B32/225—Expansion; Exfoliation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/04—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of carbon-silicon compounds, carbon or silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
    • H01B5/14—Non-insulated conductors or conductive bodies characterised by their form comprising conductive layers or films on insulating-supports

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  • the invention relates to the technical field of nanomaterials, in particular to a graphite material with a chain structure and a preparation method and application thereof.
  • Graphite is formed by stacking two-dimensional carbon atom layers arranged in a honeycomb order.
  • the carbon atoms in the carbon atom layer are covalently bonded.
  • the carbon atom layer of graphite is bonded by van der Waals force.
  • One-dimensional structure of carbon nanotubes is currently widely used as a conductive agent in lithium ion batteries, and it forms point or line contact with electrode materials; while two-dimensional structure of graphene can form surface contact with electrode materials.
  • the shrinkage resistance of surface contact is much smaller than that of line contact and point contact. Therefore, the use of graphene in batteries is beneficial to improving the battery's conductivity.
  • the diameter of current industrialized graphene is usually several hundred nanometers to several micrometers. Compared with carbon nanotubes with a length of ten or even tens of micrometers, the length is not dominant, which is not conducive to the formation of a conductive network. If the diameter of graphene is tens of micrometers, this large-diameter two-dimensional material, although it improves the electronic conductivity of the battery, will hinder the ionic conductivity of the battery; in contrast, the diameter of carbon nanotubes with a length of tens of micrometers is usually Only a few nanometers to tens of nanometers will not affect the ionic conductivity of the battery.
  • the technical problem to be solved by the present invention is to provide a graphite material with a chain structure in order to overcome the lack of conductive materials having the advantages of both one-dimensional and two-dimensional materials in the prior art.
  • a graphite material is a chain-like structure material formed by connecting graphite sheets.
  • the average thickness of the graphite sheet is less than 1 ⁇ m, preferably less than 300 nm, further preferably less than 100 nm, even more preferably less than 30 nm, and still more preferably less than 10 nm.
  • the average diameter and average thickness ratio of the graphite sheet is not less than 5.
  • the average diameter and average thickness ratio of the graphite sheet is not less than 15.
  • a ratio of an average diameter and an average thickness of the graphite sheet is not less than 50.
  • the graphite material is a one-dimensional chain structure composed of graphite sheets, and the ratio of length to average diameter is not less than 5; further preferably, the ratio of length to average diameter is not less than 10; even more preferably The ratio between the length and the average diameter is not less than 20; still more preferably, the ratio between the length and the average diameter is not less than 50.
  • the graphite material is a two-dimensional network structure formed by connecting graphite sheets, and the ratio between the total length and the average diameter is not less than 20; further preferably, the ratio between the total length and the average diameter is not less than 100; even more preferably Ground, the ratio of the total length and the average diameter is not less than 500; still more preferably, the ratio of the total length and the average diameter is not less than 2000.
  • the graphite material is a three-dimensional network structure formed by connecting graphite sheets, and the ratio of the total length and the average diameter is not less than 100; further preferably, the ratio of the total length and the average diameter is not less than 500; even more preferably The ratio of the total length and the average diameter is not less than 2000; still more preferably, the ratio of the total length and the average diameter is not less than 10,000.
  • connection manner of the graphite sheets in the graphite material is one or more combinations of shared connection, surface contact connection, and edge contact connection, but is not limited thereto.
  • connection manner of the graphite sheets in the graphite material is one or more combinations of shared connection, surface contact connection, and edge contact connection, and at least 20% are shared connections.
  • the graphite sheet is connected in one or more combinations of surface contact and edge contact in the graphite material, and at least 40% are shared connections.
  • connection mode of the graphite sheets in the graphite material is one or more combinations of shared connection, surface contact and edge contact, and at least 60% are shared connection.
  • the invention also provides a method for preparing the graphite material, which includes the following steps:
  • the expanded graphite is mixed with a solvent to obtain a mixture; the mixture is subjected to ultrasonic treatment to obtain a graphite material having a chain structure.
  • the mass ratio of the expanded graphite to the solvent is from 1: 100 to 1: 50000.
  • the mass ratio of the expanded graphite to the solvent is 1: 200 to 1: 20000.
  • the mass ratio of the expanded graphite to the solvent is from 1: 500 to 1: 10000.
  • the mass ratio of the expanded graphite to the solvent is 1: 1000 to 1: 5000.
  • the solvent is water, ethanol, isopropanol, acetone, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, 1-vinyl-2-pyrrolidone, 1-deca One of dialkyl-2-pyrrolidone, 1-octyl-2-pyrrolidone, dimethylsulfoxide, 1,3-dimethyl-2-imidazolinone, ⁇ -butyrolactone, or benzyl benzoate Or a mixture of two or more.
  • the ultrasonic frequency is 10 to 1000 KHz
  • the ultrasonic power density is 0.1 to 150 W / cm 2
  • the ultrasonic time is 0.5 to 720 minutes.
  • the ultrasonic frequency is 15 to 500 KHz
  • the ultrasonic power density is 0.2 to 30 W / cm 2
  • the ultrasonic time is 1 to 360 minutes.
  • the ultrasonic frequency is 20 to 300 KHz
  • the ultrasonic power density is 0.3 to 10 W / cm 2
  • the ultrasonic time is 2 to 120 minutes.
  • the ultrasonic frequency is 40 to 200 KHz
  • the ultrasonic power density is 0.3 to 3 W / cm 2
  • the ultrasonic time is 4 to 50 minutes.
  • the invention also provides an application of the graphite nanomaterial in preparing a conductive material or a transparent conductive film.
  • the invention also provides a battery, which contains the graphite nanomaterial.
  • the present invention also provides an electronic product including a battery, the battery containing the above-mentioned graphite material with a chain structure.
  • a battery the battery containing the above-mentioned graphite material with a chain structure.
  • mobile phones and laptops contain the batteries.
  • the present invention also provides a vehicle including a battery, the battery containing the above-mentioned graphite material in a chain structure.
  • the present invention provides a graphite material with a completely new structure.
  • the graphite material is a chain structure material formed by connecting graphite sheets; this novel chain material can be used as a conductive agent for batteries.
  • this novel chain material can be used as a conductive agent for batteries.
  • it will form surface contact with electrode materials like conventional graphite or graphene materials, which will help reduce contact resistance.
  • it is similar to carbon nanotubes on a one-dimensional scale, which facilitates the formation of a conductive network.
  • the graphite material of the novel chain structure is used in a battery, and has excellent electronic conductivity and ionic conductivity; since it is composed of a graphite sheet having a chain structure, its total length is greater than that of graphene, so its electrons
  • the electrical conductivity is better than graphene; on the other hand, because it is composed of two-dimensional graphene or nanographite sheet, it can form surface contact with the electrode material, so its shrinkage resistance is smaller than that of carbon nanotubes. It is stated that the graphite material of the present invention has the advantages of both one-dimensional and two-dimensional carbon materials, and successfully overcomes the problem that the existing two-dimensional graphene material increases the diameter and improves the electronic conductivity while reducing the ion conductivity.
  • the preparation method provided by the present invention has low cost and simple process; one-dimensional chain structure graphite materials of different lengths, thicknesses and diameters can be obtained by adjusting the process parameters; two-dimensional network structure or three-dimensional space network structure can also be formed Chain-like graphite material.
  • a two-dimensional structure of graphene was torn along the dotted line to generate several small graphene sheets. Each small graphene sheet was shared with each other and formed of graphene.
  • the material of the chain structure that is, the graphene chain, can be several times or even hundreds of times the diameter of the original graphene; the conductivity of this graphene chain on a one-dimensional scale is similar to that of single-walled carbon nanotubes.
  • Graphene properties Since the graphite material of the present invention has excellent conductive properties, it can be used as a conductive material for further preparing batteries, and electronic products and vehicles with batteries.
  • Figure 1 Graphite sheet connection in a chain-structured graphite material.
  • FIG. 2 is a schematic diagram of a graphene chain formed by partially tearing a single layer of graphene.
  • FIG. 3 is an optical microscope image of the graphite material with a chain structure prepared in Example 1.
  • FIG. 4 is a small multiple optical microscope image of the graphite material with a chain structure prepared in Example 2.
  • FIG. 4 is a small multiple optical microscope image of the graphite material with a chain structure prepared in Example 2.
  • FIG. 5 is a large-magnification optical microscope image of the graphite material with a chain structure prepared in Example 2.
  • FIG. 6 is an optical microscope image of the graphite material with a chain structure prepared in Example 3.
  • FIG. 6 is an optical microscope image of the graphite material with a chain structure prepared in Example 3.
  • FIG. 7 is an optical microscope image of the graphite material with a chain structure prepared in Example 4.
  • FIG. 8 is an optical microscope image of the graphite material with a chain structure prepared in Example 5.
  • FIG. 9 is an optical microscope image of the graphite material with a chain structure prepared in Example 6.
  • FIG. 10 is an optical microscope image of the graphite material with a chain structure prepared in Example 7.
  • FIG. 10 is an optical microscope image of the graphite material with a chain structure prepared in Example 7.
  • FIG. 11 is an optical microscope image of the graphite material with a chain structure prepared in Example 8.
  • graphite chain is an abbreviation for a chain-structured graphite material.
  • graphene chain refers to a graphitic material of a chain structure formed by the connection of graphene.
  • the term “thickness of the graphite sheet” is the length in the direction of the vertical carbon atomic layer in the graphite sheet.
  • diameter of a graphite sheet is a diameter corresponding to a circle having the same area as the carbon atomic layer in the graphite sheet.
  • the term "average thickness” refers to the thickness at which the cumulative thickness distribution percentage of the graphite flakes constituting the graphite chain reaches 50%.
  • the thickness of the graphite sheet can be measured by an atomic force microscope (AFM) or a scanning electron microscope (SEM). A semi-quantitative relative thickness can be obtained with an optical microscope.
  • the term "average diameter” refers to the diameter at which the cumulative diameter distribution percentage of the graphite flakes constituting the graphite chain reaches 50%.
  • the diameter of the graphite sheet can be measured by AFM, optical microscope, SEM or transmission electron microscope (TEM). The optical microscope can measure the diameter of the graphite sheet above the micron level.
  • one-dimensional chain structure means that the graphite sheets in the graphite chain are connected to each other and have a one-dimensional chain structure.
  • two-dimensional network structure means that the graphite sheets in a graphite chain are connected to each other to form a network structure, and are on the same two-dimensional plane.
  • three-dimensional network structure means that the graphite sheets in a graphite chain are interconnected to form a three-dimensional network structure.
  • total length refers to the sum of the lengths of all the chains in a graphite chain.
  • the length of the main chain of the one-dimensional graphite chain refers to the shortest distance between the two ends of the graphite chain through the connected graphite sheets.
  • the length of the graphite chain can be measured by AFM, optical microscope, SEM or TEM. Optical microscopy is useful for measuring the length of graphite chains in solvents, especially for three-dimensionally structured graphite chains.
  • FIG. 1A is a sharing connection method
  • FIG. 1A and the lower figure are two graphite sheets sharing a part of the graphite layer
  • FIG. 1A and the upper figure are a partial enlargement of the lower figure, showing that the two graphite sheets share a part of the graphite layer.
  • the shared connection of graphite sheets can be judged by AFM, optical microscope, SEM or TEM.
  • FIG. 1B is a surface contact connection method.
  • the bottom graphite layer of one graphite sheet and the top graphite layer of another graphite sheet are partially in contact; usually, they are connected by Van der Waals force.
  • edge contact connection means that different graphite sheets are connected together by edge contact.
  • Figure 1C is the edge contact connection method. The edges of two graphite sheets are in contact with each other, usually connected by Van der Waals force.
  • expansion volume refers to the volume of expanded graphite per unit mass of expandable graphite.
  • the sound wave pressure of ultrasonic vibration propagating in a liquid reaches an atmospheric pressure, its power density is 0.35 w / cm 2 , and a shock wave phenomenon caused by the bursting of numerous small cavitation bubbles is called a "cavitation" phenomenon.
  • Too small power density cannot produce cavitation effect, the higher the power density, the stronger the cavitation effect; but too high power density will destroy the chain structure.
  • ultrasonic device refers to an ultrasonic generating device including, but not limited to, an ultrasonic cleaner, an ultrasonic crusher.
  • the mass concentration of expanded graphite in this embodiment is 0.01%.
  • the mass ratio of expanded graphite to solvent will affect the yield of the chain structure.
  • a lower mass concentration of expanded graphite is beneficial to the formation of a chain-like structure; however, too low a concentration will cause too low a yield and a waste of solvents.
  • the size of the expansion volume will affect the thickness of the graphite sheet of the chain structure.
  • the high expansion volume facilitates the formation of thinner graphite sheets.
  • the graphite chains shown in the optical microscope picture in Figure 3 are mainly one-dimensional chain-like materials made of graphite flakes.
  • the diameter of the graphite sheet measured was mainly between 0.5 and 2 ⁇ m.
  • Most graphite flakes have a certain degree of transparency under an optical microscope. This is because the absorption rate of incident light by a single graphite layer is about 2.3%, and most of these graphite flakes are less than 100 layers, so there will be some Incident light will pass through these graphite sheets.
  • atomic force microscope the thickness of most of these graphite flakes was measured to be between 3 and 20 nm, which is consistent with the data of the optical microscope.
  • These graphite flakes typically have a diameter and thickness ratio greater than 100.
  • the graphite chains in Figure 3 are one-dimensional, some have branched structures.
  • the length of most of the graphite chains in Figure 3 is between 10 and 100 ⁇ m (including the length of the branch chains).
  • the ratio of the length to the average diameter of the graphite sheet is 5 or more.
  • Such one-dimensional graphite chains are interconnected to form a two-dimensional network structure or a three-dimensional network structure.
  • this one-dimensional graphite chain is equivalent to the length of carbon nanotubes used in lithium-ion batteries.
  • a conductive network is formed in the battery like carbon nanotubes; the average diameter of the graphite chain is comparable to the diameter of the electrode active material.
  • the effect of ionic conductivity is small, because the graphite sheet will make surface contact with the electrode material, which reduces the contact resistance and improves the electronic conductivity of the battery. Therefore, this graphite chain has the advantages of both one-dimensional carbon material and two-dimensional carbon material, and will be widely used in fields such as batteries.
  • FIG. 4 is a light microscope image of a small multiple, showing that the graphite nanomaterial with a chain structure can form a length of several hundred micrometers and has a large number of branched structures.
  • FIG. 5 is a large-magnification optical microscope view, showing that the diameter of the graphite sheet constituting the graphite chain is mainly between 2 and 10 ⁇ m, and the ratio of the length of most graphite chains to the average diameter of the graphite sheet is more than 20. These graphite flakes have a thickness between 10 and 30 nm, and the diameter-to-thickness ratio is usually greater than 50.
  • Figure 5 also shows that there are different connection methods between the graphite sheets that make up the graphite chain. There are shared connection methods that share graphite layers, surface contact connection methods, and edge contact connection methods.
  • Fig. 6 shows that the graphite sheet forms a two-dimensional network chain-like graphite chain, and the diameter of the graphite sheet is mainly between 1 and 4 ⁇ m. These graphite flakes have a thickness between 5 and 20 nm, and the diameter-to-thickness ratio is usually greater than 50.
  • This two-dimensional graphene chain is mainly made up of single-layer or multi-layer graphene with a diameter of several hundred nanometers to 1 micron, and the diameter and thickness ratio is usually greater than 50.
  • Figure 7 shows that the transparent conductive film formed by a two-dimensional graphene chain has a high light transmittance, which can be as high as 99% or more, which is much higher than the current graphene transparent conductive film made by vapor deposition (CVD). .
  • the two-dimensional structure of the graphene chain is not only cheap, but also has performance advantages.
  • the three-dimensional graphite chain shown in FIG. 8 is formed by connecting graphite sheets having a diameter of 3 to 15 ⁇ m.
  • the thickness of the graphite sheet is between 10 and 50 nm, and the diameter-to-thickness ratio is usually greater than 60. If graphene with a three-dimensional network structure is applied to a battery, a three-dimensional conductive network is formed, which reduces the internal resistance of the battery and improves the charge and discharge performance of the battery.
  • the graphite chain shown in FIG. 9 is formed by connecting graphite sheets having a diameter of 3 to 9 ⁇ m.
  • the thickness of the graphite sheet is between 5 and 20 nm, and the diameter to thickness ratio is usually greater than 100.
  • the graphite chain shown in FIG. 10 is mainly formed by connecting graphite sheets having a diameter of 5 to 15 ⁇ m to form a three-dimensional network.
  • the thickness of the graphite sheet is between 10 and 50 nm, and the diameter to thickness ratio is usually greater than 100.
  • the graphite chain shown in the optical microscope picture in FIG. 11 is a three-dimensional network chain-like material formed by connecting graphite sheets.
  • the diameter of the graphite sheet is mostly between 10 and 40 ⁇ m.
  • AFM atomic force microscope
  • the thickness of most of these graphite flakes was measured to be between 5 and 40 nm, which is consistent with the data of optical microscope.
  • Most of these graphite sheets have a diameter and thickness ratio of not less than 20.
  • the graphite chain-containing mixture obtained in Example 8 was allowed to stand for 24 hours, and the supernatant liquid was poured to obtain a mixture having a volume of 500 ml and a solid content of 0.2%.
  • conductive carbon black Super-P 0.04 g of conductive carbon black Super-P and 20 g of an ethanol aqueous solution (15% ethanol concentration) were mixed, and the mixture was sonicated for 30 minutes to obtain a conductive carbon black dispersion with a content of 0.2%.
  • conductive carbon black Super-P 0.4 g of conductive carbon black Super-P and 20 g of an aqueous ethanol solution (15% ethanol concentration) were mixed, and the mixture was sonicated for 30 minutes to obtain a conductive carbon black dispersion with a content of 2%.
  • Example 9 The resistivities of Example 9 and Comparative Examples 1 to 4 are listed in Table 1.
  • the graphite chain Comparing the ethanol solution containing 0.2% of the conductive material in Table 1, the graphite chain has a conductivity of 157 times that of carbon nanotubes and 526 times that of conductive carbon black.
  • concentration of carbon nanotubes is too low, the carbon nanotubes cannot form an effective three-dimensional conductive network, so the resistivity of a 0.2% carbon nanotube dispersion is nearly 100 times that of a 2% carbon nanotube dispersion.
  • the electrical conductivity of the carbon nanotube dispersion with a content of 2% is inferior to the graphite chain dispersion with a content of 0.2%. From the above data, it can be seen that the conductivity of graphite chains is better than that of carbon nanotubes and conductive carbon black.
  • Graphite chains can form an effective three-dimensional conductive network at a mass concentration of 0.2%.
  • Carbon nanotubes and conductive carbon black are currently the mainstream conductive agents in lithium-ion batteries.
  • the above results can be inferred that if graphite chains are used in lithium ion batteries, the amount of conductive agent can be greatly reduced, and the performance of the batteries can be improved.

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Abstract

本发明涉及纳米材料技术领域，具体公开了一种链状结构石墨纳米材料及其制备方法和应用。所述的链状结构石墨纳米材料是由厚度为0.3～100nm的石墨片相连而成的链状结构材料。该链状结构石墨纳米材料的制备工艺简单，可以通过调节工艺参数和原料，获得不同长度、厚度和直径的链状石墨材料，还可以形成二维网络结构或三维空间网络结构。所述链状结构石墨纳米材料具有优异的导电性能，兼具一维碳材料和二维碳材料的优点，可作为导电材料使用；进一步可以用于制备电池。

Description

一种石墨材料及其制备方法和应用 技术领域
本发明涉及纳米材料技术领域，具体涉及一种链状结构石墨材料及其制备方法和应用。
背景技术
石墨是由蜂窝状有序排列的二维碳原子层堆叠而形成的，碳原子层中的碳原子之间是共价键结构，石墨的碳原子层与层之间是通过范德华力结合。
2004年，英国科学家安德烈·盖姆和康斯坦丁·诺沃肖洛夫发现了由一层碳原子层构成的石墨烯。这种材料具有优异的电学、热学、光学及力学特性。石墨烯在室温下的载流子迁移率约为15000cm 2v -1s -1，是目前导电性最好的材料。
锂离子电池如今面临着能量密度和快速充电等瓶颈问题。解决这些问题首先要降低电池的内阻，这就需要更为优异的导电材料。一维结构的碳纳米管目前作为导电剂广泛应用于锂离子电池中，它与电极材料之间形成点接触或线接触；而二维结构的石墨烯，可与电极材料形成面接触。通常，面接触的收缩电阻要比线接触和点接触小很多。因此，石墨烯用于电池，有利于改善电池的导电性能。
然而，目前工业化的石墨烯的直径通常是几百纳米到几微米，和长度十几甚至几十微米的碳纳米管相比，长度上不占优势，不利于形成导电网络。如果石墨烯的直径是几十微米，这种大直径的二维材料尽管提升了电池的电子导电，但会阻碍电池的离子导电；相比而言，几十微米长度的碳纳米管的直径通常只有几纳米到几十纳米，并不会影响电池的离子导电。
因此，开发一种新的兼具一维及二维材料优点的导电材料具有广阔的市场前景。
发明内容
本发明所要解决的技术问题是，为了克服现有技术中缺乏兼具一维及二维材料优点的导电材料的不足，提供一种链状结构的石墨材料。
本发明所要解决的上述技术问题，通过以下技术方案予以实现：
一种石墨材料，所述的石墨材料是由石墨片相连而成的链状结构材料。
优选地，所述的石墨片的平均厚度为小于1μm，优选小于300nm，进一步优选小于100nm，更进一步优选小于30nm，再进一步优选小于10nm。
优选地，所述石墨片的平均直径和平均厚度比不小于5。
进一步优选地，所述石墨片的平均直径和平均厚度比不小于15。
更进一步优选地，所述石墨片的平均直径和平均厚度比不小于50。
优选地，所述石墨材料是由石墨片相连而成的一维链状结构，并且长度和平均直径比不小于5；进一步优选地，所述长度和平均直径比不小于10；更进一步优选地，所述长度和平均直径比不小于20；再进一步优选地，所述长度和平均直径比不小于50。
优选地，所述石墨材料是由石墨片相连而成的二维网络结构，并且总长度和平均直径比不小于20；进一步优选地，所述总长度和平均直径比不小于100；更进一步优选地，所述总长度和平均直径比不小于500；再进一步优选地，所述总长度和平均直径比不小于2000。
优选地，所述石墨材料是由石墨片相连而成的三维网络结构，并且总长度和平均直径比不小于100；进一步优选地，所述总长度和平均直径比不小于500；更进一步优选地，所述总长度和平均直径比不小于2000；再进一步优选地，所述总长度和平均直径比不小于10000。
优选地，所述石墨材料中石墨片的连接方式是共享连接、面接触连接以及边缘接触连接的一种或几种组合，但不限于此。
进一步优选地，所述石墨材料中石墨片的连接方式是共享连接、面接触连接以及边缘接触连接的一种或几种组合，且至少有20％是共享连接。
更进一步优选地，所述石墨材料中石墨片的连接方式是共享连接，面接触以及边缘接触的一种或几种组合，且至少有40％是共享连接。
再进一步优选地，所述石墨材料中石墨片的连接方式是共享连接，面接触以及边缘接触的一种或几种组合，且至少有60％是共享连接。
本发明还提供一种上述石墨材料的制备方法，其包含如下步骤：
将膨胀石墨与溶剂混合，得到混合物；将混合物进行超声处理，得到链状结构石墨材料。
优选地，膨胀石墨与溶剂的质量比为1:100～1:50000。
进一步优选地，膨胀石墨与溶剂的质量比为1:200～1:20000。
更进一步优选地，膨胀石墨与溶剂的质量比为1:500～1:10000。
再进一步优选地，膨胀石墨与溶剂的质量比为1:1000～1:5000。
优选地，所述的溶剂采用的是水、乙醇、异丙醇、丙酮、二甲基甲酰胺、二甲基乙酰胺、N-甲基吡咯烷酮、1-乙烯基-2-吡咯烷酮、1-十二烷基-2-吡咯烷酮、1-辛基-2-吡咯烷酮、二甲亚砜、1,3-二甲基-2-咪唑啉酮、γ-丁内酯或苯甲酸苄酯中的一种或两种以上的混合。
优选地，超声频率为10～1000KHz，超声功率密度为0.1～150W/cm 2，超声时间为0.5～720分钟。
进一步优选地，超声频率为15～500KHz，超声功率密度为0.2～30W/cm 2，超声时间为1～360分钟。
更进一步优选地，超声频率为20～300KHz，超声功率密度为0.3～10W/cm 2，超声时间为2～120分钟。
再进一步优选地，超声频率为40～200KHz，超声功率密度为0.3～3W/cm 2，超声时间为4～50分钟。
本发明还提供一种上述石墨纳米材料在制备导电材料或透明导电膜中的应用。
本发明还提供一种电池，其含有上述石墨纳米材料。
本发明还提供一种电子产品，其包含电池，所述的电池含有上述链状结构石墨材料。例如，手机和笔记本电脑包含所述电池。
本发明还提供一种交通工具，其包含电池，所述的电池含有上述链状结构石墨材料。
有益效果：(1)本发明提供了一种全新结构的石墨材料，所述的石墨材料是由石墨片相连而成的链状结构材料；这种新颖的链状材料可作为导电剂用于电池中，它会像常规的石墨或石墨烯材料一样，与电极材料形成面接触，这有利于降低接触电阻；同时一维尺度上类似于碳纳米管，便于 形成导电网络。(2)所述新颖链状结构的石墨材料用于电池中，具有优异电子导电能力和离子导电能力；由于其是由链状结构的石墨片组成，其总长度要大于石墨烯，因此其电子导电能力要优于石墨烯；另一方面，也由于其是由二维结构的石墨烯或纳米石墨片组成，能与电极材料形成面接触，因此其收缩电阻要小于碳纳米管；综上所述，本发明所述的石墨材料兼具一维和二维碳材料的优点，成功克服了现有二维石墨烯材料增大直径提升电子导电能力的同时会导致离子导电能力下降的问题。(3)本发明所提供的制备方法成本低、工艺简单；可以通过调节工艺参数，获得不同长度、厚度和直径的一维链状结构石墨材料；还可以形成二维网络结构或三维空间网络结构的链状石墨材料。(4)如图2所示，一块二维结构的石墨烯，沿虚线撕裂，产生几块小石墨烯片，每块小石墨烯片相互之间是共享连接，形成了由石墨烯组成的链状结构材料，即石墨烯链，长度可达原有石墨烯直径的几倍甚至上百倍；这种石墨烯链在一维尺度上的导电性能类似于单壁碳纳米管，同时兼有二维石墨烯的性能。(5)由于本发明所述的石墨材料具有优异的导电性能，因此其可以用于作为导电材料进一步用于制备电池，以及带电池的电子产品和交通工具。
附图说明
图1链状结构石墨材料中的石墨片连接方式。
图2单层石墨烯部分撕裂后形成石墨烯链的示意图。
图3实施例1所制备的链状结构石墨材料的光学显微镜图。
图4实施例2所制备的链状结构石墨材料的小倍数光学显微镜图。
图5实施例2所制备的链状结构石墨材料的大倍数光学显微镜图。
图6实施例3所制备的链状结构石墨材料的光学显微镜图。
图7实施例4所制备的链状结构石墨材料的光学显微镜图。
图8实施例5所制备的链状结构石墨材料的光学显微镜图。
图9实施例6所制备的链状结构石墨材料的光学显微镜图。
图10实施例7所制备的链状结构石墨材料的光学显微镜图。
图11实施例8所制备的链状结构石墨材料的光学显微镜图。
具体实施方式
术语
如本文所用，术语“石墨链”是链状结构石墨材料的简称。
如本文所用，术语“石墨烯链”是指由石墨烯相连而成的链状结构石墨材料。
如本文所用，术语“石墨片的厚度”是石墨片中垂直碳原子层的方向的长度。
如本文所用，术语“石墨片的直径”是和石墨片中碳原子层的面积相等的圆对应的直径。
如本文所用，术语“平均厚度”指组成石墨链的石墨片的累计厚度分布百分数达到50％时所对应的厚度。石墨片的厚度可通过原子力显微镜(AFM)或扫描电子显微镜(SEM)测得，光学显微镜可获得半定量的相对厚度。
如本文所用，术语“平均直径”指组成石墨链的石墨片的累计直径分布百分数达到50％时所对应的直径。石墨片的直径可通过AFM、光学显微镜、SEM或透射电子显微镜(TEM)测得，光学显微镜可测量微米级别以上的石墨片的直径。
如本文所用，术语“一维链状结构”指石墨链中的石墨片相互连接，具有一维链状结构。
如本文所用，术语“二维网络结构”指石墨链中的石墨片相互连接，形成网络结构，且在同一个二维平面上。
如本文所用，术语“三维网络结构”指石墨链中的石墨片相互连接，形成三维网络结构。
如本文所用，术语“总长度”指石墨链中所有链的长度总和。一维石墨链的主链的长度是指经过相互连接的石墨片，连接石墨链两端的最短距离。石墨链的长度可通过AFM、光学显微镜、SEM或TEM测得。光学显微镜有利于测量在溶剂中的石墨链的长度，尤其是三维结构石墨链的长度。
如本文所用，术语“共享连接”指不同石墨片之间通过共享部分石墨层连接在一起。图1A是共享连接方式，图1A下图是两块石墨片共享部分石墨层，图1A上图是下图的局部放大，显示两块石墨片之间共享部分石墨层。 石墨片的共享连接可通过AFM、光学显微镜、SEM或TEM来判断。
如本文所用，术语“面接触连接”指不同石墨片之间通过石墨层上下面接触，连接在一起。图1B是面接触连接方式，一块石墨片的底部石墨层和另一块石墨片的顶部石墨层部分接触；通常是通过范德华力相连。
如本文所用，术语“边缘接触连接”指不同石墨片之间通过边缘接触连接在一起。图1C是边缘接触连接方式，两块石墨片边缘之间相接触，通常是通过范德华力相连。
如本文所用，术语“膨胀容积”指单位质量的可膨胀石墨膨胀后的体积。
如本文所用，术语“超声功率密度”指单位超声面积的超声功率，即超声功率密度p＝超声功率(W)/超声面积(cm 2)。通常p≥0.3w/cm 2。当超声波振动在液体中传播的音波压强达到一个大气压时，其功率密度为0.35w/cm 2，会形成由无数细小的空化气泡破裂而产生的冲击波现象，称为“空化”现象。太小的功率密度无法产生空化效应，功率密度越高，空化效果越强；但太高的功率密度会破坏链状结构。
如本文所用，术语“超声装置”指超声波发生装置，包括但不限于：超声波清洗机、超声波破碎机。
以下结合具体实施例来进一步解释本发明，但实施例对本发明不做任何形式的限定。
实施例1
将50mg膨胀容积为600mL/g的膨胀石墨和500g乙醇水溶液(乙醇质量浓度为10％)混合，将混合物用频率为68KHz，功率为50W，超声功率密度为0.36w/cm 2的超声装置处理，超声10分钟，可获得图3所示的石墨链。
本实施例中的膨胀石墨质量浓度为0.01％。膨胀石墨和溶剂的质量比会影响链状结构的产率。较低的膨胀石墨质量浓度会有利于形成链状结构；但过低的浓度会造成产量过低和溶剂浪费。
膨胀容积的大小会影响链状结构的石墨片的厚度。高的膨胀容积有利于形成更薄的石墨片。
图3的光学显微镜图片所显示的石墨链主要是由石墨片相连而成的一 维链状材料。测得石墨片的直径主要在0.5～2μm之间。大部分石墨片在光学显微镜下有一定的透明度，这是由于单层的石墨层对入射光的吸收率约为2.3％，而这些石墨片的层数大部分在100层以下，所以会有部分入射光会透过这些石墨片。石墨片厚度越小，光学显微镜下越透明；因而在一定厚度范围，可以根据透明度判断石墨片的相对厚度。通过原子力显微镜(AFM)，测得这些石墨片的厚度大部分在3～20nm之间，和光学显微镜的数据符合。这些石墨片的直径和厚度比通常大于100。
图3的石墨链，大部分是一维链状，有些还有支链结构，图3中大部分石墨链的长度在10～100μm之间(包含支链的长度)，大部分石墨链的总长度和石墨片平均直径的比值在5以上。这种一维石墨链相互连接，可形成二维网络结构的石墨链或者三维网络结构的石墨链。
这种一维石墨链的长度和锂离子电池用的碳纳米管的长度相当，在电池中会像碳纳米管一样形成导电网络；石墨链的平均直径大小和电极活性材料的直径相当，对电池的离子导电影响不大，由于石墨片会和电极材料形成面接触，降低了接触电阻，会提升电池的电子导电性能。因而，这种石墨链兼具了一维碳材料和二维碳材料的优点，会在电池等领域获得广泛应用。
实施例2
将100mg膨胀容积为400mL/g的膨胀石墨和500g乙醇水溶液(乙醇质量浓度为15％)混合，将混合物用频率为40KHz，功率为50W，超声功率密度为0.36w/cm 2的超声装置处理，超声5分钟，可获得图4和图5所示的石墨链。
图4是小倍数的光学显微镜图，显示链状结构的石墨纳米材料可形成几百微米的长度，并有大量的支链结构。图5是大倍数的光学显微镜图，显示组成石墨链的石墨片直径主要在2～10μm之间，大部分石墨链的长度和石墨片平均直径的比值在20以上。这些石墨片的厚度在10～30nm之间，直径和厚度比通常大于50。通过改变工艺参数和原料，获得了和实施例1不同长度、不同直径和不同厚度的石墨链。图5还显示，组成石墨链的石墨片之间存在着不同的连接方式，有共享石墨层的共享连接方式，也有面接触连接方式，还有边缘接触连接方式。
实施例3
将6g膨胀容积为500mL/g的膨胀石墨和3000g乙醇水溶液(乙醇质量浓度为15％)混合，将混合物用频率为40KHz，功率为240W的超声装置处理，超声功率密度为0.36w/cm 2，超声60分钟，可获得图6所示的石墨链。
图6显示，石墨片组成了二维网络链状结构的石墨链，石墨片直径主要在1～4μm之间。这些石墨片的厚度在5～20nm之间，直径和厚度比通常大于50。
实施例4
将250mg膨胀容积为800mL/g的膨胀石墨和500g二甲基甲酰胺混合，将混合物用频率为120KHz，功率为60W的超声装置处理，超声功率密度为0.48w/cm 2，超声20分钟，将超声后的混合液滴加到玻璃片上，可获得图7所示的由二维网络石墨烯链形成的透明导电膜。
这种二维石墨烯链主要是由直径为几百纳米到1微米的单层或多层石墨烯连接而成，直径和厚度比通常大于50。图7显示，这种由二维结构的石墨烯链形成的透明导电膜透光率很高，可以高达99％以上，比目前气相化学沉积(CVD)制作的石墨烯透明导电膜要高得多。二维结构的石墨烯链用来制作透明导电膜不仅成本低廉，而且具有性能优势。
实施例5
将0.5g膨胀容积为400mL/g的膨胀石墨和500g N-甲基吡咯烷酮混合，将混合物用频率为40KHz，功率为50W的超声装置处理，超声功率密度为0.36w/cm 2，超声5分钟，可获得图8所示的三维网络空间的石墨链。
图8所示的三维石墨链是由直径为3～15μm的石墨片连接而成，石墨片的厚度在10～50nm之间，直径和厚度比通常大于60。若将三维网络结构的石墨烯应用于电池中，会形成三维的导电网络，降低了电池的内阻，将提升电池的充放电性能。
实施例6
将50mg膨胀容积为600mL/g的膨胀石墨和500g N-甲基吡咯烷酮混合，将混合物用频率为40KHz，功率为240W，超声功率密度为0.36w/cm 2的超声装置处理，超声10分钟，可获得图9所示的石墨链。
图9所示的石墨链是由直径为3～9μm的石墨片连接而成，石墨片的厚度在5～20nm之间，直径和厚度比通常大于100。
实施例7
将100mg膨胀容积为400mL/g的膨胀石墨和500g N-甲基吡咯烷酮混合，将混合物用频率为40KHz，功率为50W，超声功率密度为0.36w/cm 2的超声装置处理，超声5分钟，可获得图10所示的石墨链。
图10所示的石墨链主要是由直径为5～15μm的石墨片连接而成，形成三维网络，石墨片的厚度在10～50nm之间，直径和厚度比通常大于100。
实施例8
将1g膨胀容积为400mL/g的膨胀石墨和5kg乙醇水溶液(乙醇质量浓度为12％)混合，将混合物用频率为40KHz，超声功率240W，超声功率密度为0.36W/cm 2的超声装置处理，超声15分钟，可获得含有图11所示的石墨链的混合物。
图11的光学显微镜图片所显示的石墨链是由石墨片相连而成的三维网络链状材料。石墨片的直径大部分在10～40μm之间。通过原子力显微镜(AFM)，测得这些石墨片的厚度大部分在5～40nm之间，和光学显微镜的数据符合。这些石墨片的直径和厚度比大部分不小于20。
实施例9
将实施例8所获得的含有石墨链的混合物静置24小时，倾倒上层清液，得到体积为500ml的混合物，固含量为0.2％。
对比例1
将0.04g碳纳米管和20g乙醇水溶液(乙醇质量浓度为15％)混合，将混合物超声处理30分钟，获得含量为0.2％的碳纳米管分散液。
对比例2
将0.4g碳纳米管和20g乙醇水溶液(乙醇质量浓度为15％)混合，将 混合物超声处理30分钟，获得含量为2％的碳纳米管分散液。
对比例3
将0.04g导电炭黑Super-P和20g乙醇水溶液(乙醇质量浓度为15％)混合，将混合物超声处理30分钟，获得含量为0.2％的导电炭黑分散液。
对比例4
将0.4g导电炭黑Super-P和20g乙醇水溶液(乙醇质量浓度为15％)混合，将混合物超声处理30分钟，获得含量为2％的导电炭黑分散液。
将实施例9、对比例1～4的电阻率列于表1中。
表1实施例9及对比例1～4的电阻率
Figure PCTCN2019088105-appb-000001
将表1中含有0.2％的导电材料的乙醇水溶液进行比较，石墨链电导率是碳纳米管的157倍，导电炭黑的526倍。当碳纳米管的浓度过低时，碳纳米管不能形成有效的三维导电网络，因而0.2％的碳纳米管分散液电阻率是2％的碳纳米管分散液的近100倍。含量为2％的碳纳米管分散液的电导率比不上含量为0.2％的石墨链分散液。从以上数据看出，石墨链导电性能要优于碳纳米管和导电炭黑，石墨链在0.2％的质量浓度下就可以形成有效的三维导电网络。
碳纳米管和导电炭黑是目前锂离子电池中的主流导电剂。以上结果可以推断出，石墨链若用于锂离子电池，可以大幅减少导电剂的用量，提升电池的性能。

Claims (15)

  1. 一种石墨材料，其特征在于，所述的石墨材料是由石墨片相连而成的链状结构材料。
  2. 如权利要求1所述的石墨材料，其特征在于，石墨片的平均厚度为小于1μm，优选小于300nm，进一步优选小于100nm，更进一步优选小于30nm，再进一步优选小于10nm。
  3. 如权利要求1所述的石墨材料，其特征在于，所述石墨片的平均直径和平均厚度比不小于5；进一步优选地，所述石墨片的平均直径和平均厚度比不小于15；更进一步优选地，所述石墨片的平均直径和平均厚度比不小于50。
  4. 如权利要求1所述的石墨材料，其特征在于，所述石墨材料是由石墨片相连而成的一维链状结构，并且长度和平均直径比不小于5；进一步优选地，所述长度和平均直径比不小于10；更进一步优选地，所述长度和平均直径比不小于20；再进一步优选地，所述长度和平均直径比不小于50。
  5. 如权利要求1所述的石墨材料，其特征在于，所述石墨材料是由石墨片相连而成的二维网络链状结构，并且总长度和平均直径比不小于20；进一步优选地，所述总长度和平均直径比不小于100；更进一步优选地，所述总长度和平均直径比不小于500；再进一步优选地，所述总长度和平均直径比不小于2000。
  6. 如权利要求1所述的石墨材料，其特征在于，所述石墨材料是由石墨片相连而成的三维网络链状结构，并且总长度和平均直径比不小于100；进一步优选地，所述总长度和平均直径比不小于500；更进一步优选地，所述总长度和平均直径比不小于2000；再进一步优选地，所述总长度和平均直径比不小于10000。
  7. 如权利要求1所述的石墨材料，其特征在于，所述石墨材料中石墨片的连接方式是共享连接、面接触连接以及边缘接触连接的一种或几种组合，但不限于此；进一步优选地，所述石墨材料中石墨片的连接方式中至少有20％是共享连接；更进一步优选地，所述石墨材料中石墨片的连接方式中至少有40％是共享连接；再进一步优选地，所述石墨材料中石墨片的 连接方式中至少有60％是共享连接。
  8. 权利要求1～7任一项所述的石墨材料的制备方法，其特征在于，包含如下步骤：
    将膨胀石墨与溶剂混合，得到混合物；将混合物进行超声处理，得到链状结构石墨材料。
  9. 如权利要求8所述的石墨材料的制备方法，其特征在于，膨胀石墨与溶剂的质量比为1:100～1:50000；进一步优选地，膨胀石墨与溶剂的质量比为1:200～1:20000；更进一步优选地，膨胀石墨与溶剂的质量比为1:500～1:10000；再进一步优选地，膨胀石墨与溶剂的质量比为1:1000～1:5000。
  10. 如权利要求8所述的石墨材料的制备方法，其特征在于，所述的溶剂采用的是水、乙醇、异丙醇、丙酮、二甲基甲酰胺、二甲基乙酰胺、N-甲基吡咯烷酮、1-乙烯基-2-吡咯烷酮、1-十二烷基-2-吡咯烷酮、1-辛基-2-吡咯烷酮、二甲亚砜、1,3-二甲基-2-咪唑啉酮、γ-丁内酯或苯甲酸苄酯中的一种或两种以上的混合。
  11. 如权利要求8所述的石墨材料的制备方法，其特征在于，超声频率为10～1000KHz，超声功率密度为0.1～150W/cm 2，超声时间为0.5～720分钟；进一步优选地，超声频率为15～500KHz，超声功率密度为0.2～30W/cm 2，超声时间为1～360分钟；更进一步优选地，超声频率为20～300KHz，超声功率密度为0.3～10W/cm 2，超声时间为2～120分钟；再进一步优选地，超声频率为40～200KHz，超声功率密度为0.3～3W/cm 2，超声时间为4～50分钟。
  12. 权利要求1～7任一项所述的石墨材料在制备导电材料或透明导电膜中的应用。
  13. 一种电池，其特征在于，含有权利要求1～7任一项所述的石墨材料。
  14. 一种电子产品，其特征在于，包含电池，所述的电池含有权利要求1～7任一项所述的石墨材料。
  15. 一种交通工具，其特征在于，包含电池，所述的电池含有权利要求1～7任一项所述的石墨材料。
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CN101746755A (zh) * 2009-12-14 2010-06-23 重庆大学 一种多层石墨烯的制备方法
CN103466605A (zh) * 2013-08-22 2013-12-25 广东工业大学 一种纳米石墨片的制备方法
CN103803533A (zh) * 2012-11-15 2014-05-21 福建省辉锐材料科技有限公司 一种石墨烯的制备方法
CN104891485A (zh) * 2015-06-08 2015-09-09 哈尔滨工业大学（威海） 一种纳米石墨片制备方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101746755A (zh) * 2009-12-14 2010-06-23 重庆大学 一种多层石墨烯的制备方法
CN103803533A (zh) * 2012-11-15 2014-05-21 福建省辉锐材料科技有限公司 一种石墨烯的制备方法
CN103466605A (zh) * 2013-08-22 2013-12-25 广东工业大学 一种纳米石墨片的制备方法
CN104891485A (zh) * 2015-06-08 2015-09-09 哈尔滨工业大学（威海） 一种纳米石墨片制备方法

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