WO2020125442A1 - 铝碳复合材料及其制备方法、负极、二次电池和用电设备 - Google Patents

铝碳复合材料及其制备方法、负极、二次电池和用电设备 Download PDF

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WO2020125442A1
WO2020125442A1 PCT/CN2019/123480 CN2019123480W WO2020125442A1 WO 2020125442 A1 WO2020125442 A1 WO 2020125442A1 CN 2019123480 W CN2019123480 W CN 2019123480W WO 2020125442 A1 WO2020125442 A1 WO 2020125442A1
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aluminum
preparation
composite material
carbon composite
negative electrode
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PCT/CN2019/123480
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English (en)
French (fr)
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唐永炳
王敏
刘齐荣
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深圳先进技术研究院
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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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/381—Alkaline or alkaline earth metals elements
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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 batteries, in particular to an aluminum-carbon composite material and a preparation method thereof, a negative electrode, a secondary battery, and electrical equipment.
  • lithium ion battery anode materials include graphite anodes, silicon anodes, lithium metal anodes and aluminum foil anodes.
  • graphite anode is a commercial anode material, its theoretical capacity is low, only 372mAh/g; although the capacity of silicon anode material is high, but its conductivity is poor, it can not serve as current collector and anode material at the same time.
  • the lithium metal anode has high capacity and good conductivity, its charge-discharge mechanism is the lithium dissolution-deposition mechanism, which has potential safety problems due to the easy growth of dendrites.
  • the lithium resource reserves are very limited, resulting in cost during use Keep climbing.
  • the new high-efficiency battery system based on the metal aluminum anode has the advantages of higher energy density and lower cost, but the simple aluminum foil as the negative electrode has the following problems that lead to its cycle need to be further improved: (1) lithium ion and aluminum metal alloy Significant volume expansion during the chemical process, resulting in powdering of the electrode and resulting in battery capacity decay; (2) The solid electrolyte interface layer (SEI film) formed by the reaction between aluminum metal and the electrolyte at the interface continues to thicken over time, and the interface impedance Continuously increasing, which makes the battery capacity decay; (3) Due to the continuous change of the volume of the aluminum metal anode during the charging and discharging process, the SEI film is unstable, and during the lithium deintercalation process, continuous generation-cracking-regeneration, thereby continuously consuming lithium Ionic electrolyte, resulting in reduced Coulomb efficiency.
  • SEI film solid electrolyte interface layer
  • existing solutions include electrolyte modification and carbon-coated aluminum foil methods.
  • the porosity of aluminum foil and carbon coating can solve the problems of aluminum negative electrode to a certain extent.
  • the macroscopic carbon coating will also rupture to a certain extent during the volume expansion of the aluminum anode, which cannot effectively improve the volume expansion and the capacity attenuation problem caused by the unstable SEI film.
  • the first object of the present invention is to provide an aluminum-carbon composite material to alleviate at least one of the technical problems mentioned above.
  • the second object of the present invention is to provide a method for preparing an aluminum-carbon composite material, by which a structurally strong aluminum-carbon composite material can be obtained.
  • the third object of the present invention is to provide a negative electrode including the aluminum-carbon composite material.
  • the fourth object of the present invention is to provide a secondary battery including the negative electrode.
  • a fifth object of the present invention is to provide an electric device including the secondary battery.
  • An aluminum-carbon composite material includes aluminum nanoparticles and carbon nanofibers, and the aluminum nanoparticles are coated in the carbon nanofibers.
  • a method for preparing an aluminum-carbon composite material provides an electrostatic spinning solution containing aluminum nanoparticles, and uses an electrostatic spinning process to prepare a spinning fiber, and the spinning fiber is carbonized to obtain the aluminum-carbon composite material.
  • a negative electrode includes a current collector and a negative electrode material layer.
  • the negative electrode material layer is an aluminum-carbon composite material with a thin film structure prepared by the above preparation method.
  • a secondary battery includes the negative electrode.
  • An electric device including the secondary battery.
  • the present invention has the following beneficial effects:
  • the aluminum-carbon composite material provided by the invention wraps the aluminum nanoparticles in the carbon nanofibers, and when the aluminum nanoparticles expand in volume, it is easier to expand along the length direction of the carbon nanofibers.
  • the connection strength of carbon nanofibers in its length direction is much higher than its radial strength. Therefore, the use of carbon nanofibers to coat aluminum nanoparticles can effectively improve the stability of the aluminum carbon composite structure.
  • the present invention provides aluminum-carbon composite materials with the following advantages:
  • the carbon nanofibers coated on the surface of the aluminum nanoparticles as a protective carbon layer can effectively isolate the aluminum nanoparticles from the electrolyte and prevent the aluminum nanoparticles from being eroded;
  • Aluminum nanoparticles greatly increase the specific surface area of the reaction, provide more reactive sites for alloying and adsorption, and can significantly improve the rate performance of the battery;
  • the coating of carbon nanofibers is beneficial to the formation of a stable SEI film on the electrode surface, thereby improving the stability of the interface between the negative electrode and the electrolyte;
  • carbon nanofibers coat aluminum nanoparticles, they can effectively prevent the oxidation of aluminum and maintain the activity of aluminum nanoparticles.
  • the negative electrode provided by the invention is prepared by using the aluminum-carbon composite material, and has the advantages of high coulombic efficiency, less irreversible capacity loss and good cycle stability.
  • the secondary battery provided by the invention is prepared by using the above-mentioned negative electrode, so it also has the advantages of high Coulomb efficiency, less irreversible capacity loss and good cycle stability.
  • FIG. 1 is a schematic structural diagram of an aluminum-carbon composite material according to an embodiment of the present invention.
  • Icon 10-carbon nanofibers; 11-aluminum nanoparticles.
  • the percentage (%) or part refers to the weight percentage or part by weight relative to the composition.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “6-22” means that all real numbers between “6-22” have been listed in this article, and “6-22" is just an abbreviated representation of these numerical combinations.
  • the form of the lower limit and the upper limit of the "range" disclosed in the present invention may be one or more lower limits and one or more upper limits, respectively.
  • each reaction or operation step may be performed sequentially or in order.
  • the reaction methods herein are performed sequentially.
  • the present invention provides an aluminum-carbon composite material, which includes aluminum nanoparticles and carbon nanofibers, and the aluminum nanoparticles are coated in the carbon nanofibers.
  • the aluminum-carbon composite material provided by the present invention encapsulates aluminum nanoparticles in carbon nanofibers.
  • the connection strength of carbon nanofibers in its length direction is much higher than its radial strength. Therefore, the use of carbon nanofibers to coat aluminum nanoparticles can effectively improve the stability of the aluminum carbon composite structure.
  • the present invention provides aluminum-carbon composite materials with the following advantages:
  • the carbon nanofibers coated on the surface of the aluminum nanoparticles as a protective carbon layer can effectively isolate the aluminum nanoparticles from the electrolyte and prevent the aluminum nanoparticles from being eroded;
  • Aluminum nanoparticles greatly increase the specific surface area of the reaction, provide more reactive sites for alloying and adsorption, and can significantly improve the rate performance of the battery;
  • the coating of carbon nanofibers is beneficial to the formation of a stable SEI film on the electrode surface, thereby improving the stability of the interface between the negative electrode and the electrolyte;
  • carbon nanofibers coat aluminum nanoparticles, they can effectively prevent the oxidation of aluminum and maintain the activity of aluminum nanoparticles.
  • FIG. 1 The structure of the aluminum-carbon composite material according to an embodiment of the present invention is shown in FIG. 1, which includes carbon nanofibers 10 and aluminum nanoparticles 11 coated in the carbon nanofibers.
  • the particle size of the aluminum nanoparticles is 5-100 nm, preferably 10-100 nm.
  • the particle size of the aluminum nanoparticles is typically, but not limited to, for example, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm.
  • the diameter of the carbon nanofibers is 100-2000 nm, preferably 300-1000 nm.
  • the carbon nanofibers By optimizing the diameter of the carbon nanofibers, not only can the carbon nanofibers coat the aluminum nanoparticles, but also the tensile strength of the carbon nanofibers can be ensured.
  • the diameter of the carbon nanofibers can be 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm or 2000 nm.
  • the aluminum nanoparticles account for 10% to 85% of the mass of the aluminum-carbon composite material, preferably 50% to 70%.
  • the aluminum nanoparticles By optimizing the proportion of aluminum nanoparticles, not only can the aluminum nanoparticles have a higher capacity as a negative electrode active material, but also the structural stability of the aluminum-carbon composite material.
  • the present invention provides a method for preparing an aluminum-carbon composite material, provides an electrospinning solution containing aluminum nanoparticles, and uses an electrospinning process to prepare a spinning fiber, which is obtained after carbonization of the spinning fiber Aluminum carbon composite material.
  • the aluminum-carbon composite material obtained by this method has all the advantages of the above-mentioned aluminum-carbon composite material and will not be repeated here.
  • the aluminum-carbon composite material is prepared by the electrostatic spinning process.
  • concentration and uniformity of the electrospinning solution By controlling the concentration and uniformity of the electrospinning solution, the size of the aluminum-carbon composite material and the content of aluminum nanoparticles can be effectively controlled, so that the preparation of the aluminum-carbon composite material The size meets the requirements for use.
  • the preparation method of the electrospinning solution includes: dissolving aluminum nanoparticles in a solution containing a microcapsule film-forming agent, mixing them uniformly to obtain a microcapsule suspension, and then dissolving the microcapsules After the suspension and the binder are uniformly mixed, an electrospinning solution is obtained, wherein the mass ratio of the binder to the aluminum nanoparticles can be, for example, 1:1 to 10:1.
  • the aluminum nanoparticles are coated with a microcapsule film-forming agent to form microcapsules with a core-shell structure.
  • the microcapsule structure is conducive to the uniform dispersion of aluminum nanoparticles in the binder, thereby forming a stable and uniform electrospinning solution .
  • the solvent in the electrospinning solution may be, for example, a mixed solvent of an alcoholic solvent and an etheric solvent; typical but non-limiting alcoholic solvents are at least one of methanol, ethanol, benzyl alcohol, or ethylene glycol; Ether solvents are typically, but not limited to, at least one of methyl ether, methyl ethyl ether, diethyl ether, n-propyl ether, or n-butyl ether.
  • the aluminum nanoparticles are first surface-treated with a surfactant to make the electrical properties of the surface of the aluminum nanoparticles opposite to the electrical properties of the microcapsule film-forming agent.
  • a surfactant for example, the mass ratio can be 1:1 ⁇ 10:1, and then the surface-treated aluminum particles are dispersed in the solution containing the microcapsule film-forming agent, through electrostatic adsorption between the surfactant and the microcapsule film-forming agent, In-situ polymerization coats the aluminum nanoparticles to form the microcapsule suspension.
  • the surface of aluminum nanoparticles and microcapsule film-forming agent are respectively charged with different electric charges, and the microcapsule film-forming agent is adsorbed on the surface of aluminum nanoparticles by special-phase attraction, and then on aluminum nanoparticles.
  • a coating layer is formed on the surface of the particles and becomes a microcapsule structure.
  • the particle size of the microcapsules in the obtained microcapsule suspension may be, for example, 10 to 300 nm.
  • the aluminum nanoparticles are dissolved in a surfactant, and the surface of the aluminum nanoparticles is modified so that the surface of the aluminum nanoparticles is charged accordingly, and the surface tension of the aluminum particles is significantly reduced.
  • the surfactant includes an ionic surfactant, for example, it may be at least one of stearic acid, sodium dodecylbenzenesulfonate, quaternary ammonium, lecithin, amino acid type or betaine type, preferably hard Fatty acid or sodium dodecyl sulfonate.
  • the microcapsule film-forming agent includes styrene or divinylbenzene.
  • styrene or divinylbenzene can undergo in-situ polymerization on the surface of the aluminum nanoparticles after contact with the aluminum nanoparticles, thereby forming a uniform on the surface of the aluminum nanoparticles Cladding.
  • the microcapsule film-forming agent in the present invention can also be other film-forming agents, such as gelatin, acacia, shellac, shellac, starch, dextrin, wax , Turpentine, sodium alginate, zein, chitosan, polybutadiene, polypropylene, polyether, polyurea, polyethylene glycol, polyvinyl alcohol, polyamide, polyacrylamide, polyurethane, polymethacrylic acid It is composed of natural natural polymer materials or synthetic polymer materials such as methyl ester, polyvinylpyrrolidone, epoxy resin or polysiloxane.
  • the binder includes at least one of a sugar binder, an alginate binder, a carboxymethyl cellulose salt binder, or a polyolefin binder Species.
  • the typical but non-limiting binders include gum arabic (referred to as GA), sodium alginate (sodium alginate), sodium carboxymethyl cellulose (referred to as CMC), and polyvinylpyrrolidone (referred to as PVP) ), polyacrylonitrile (PAN for short), polyvinylidene fluoride (PVDF for short), polytetrafluoroethylene (PTFE for short), polyvinyl alcohol (PVA for short), polyacrylic acid (PAA for short), polyacrylic acid Ammonium (abbreviated as PAA-NH 4 ), vinyl acetate resin (abbreviated as PVAc), polyacrylic acid-polyvinyl alcohol copolymer (abbreviated as PAA-PVA), polyvinyl alcohol-polyethyleneimine copolymer (abbreviated as PVA- PEI), polyacrylic acid-carboxymethylcellulose sodium copolymer (referred to as PAA-CMC), sodium polyacrylate grafted sodium carboxymethylcellulose (
  • the method for preparing an aluminum-carbon composite material includes the following steps:
  • Electrostatic spinning solution is obtained after mixing microcapsule suspension and binder uniformly;
  • the compatibility between the nano aluminum and the binder is increased, and the dispersibility of the nano aluminum in the electrospinning solution is improved, thereby obtaining a uniformly dispersed electrospinning solution;
  • the obtained electrospinning solution is added to an electrospinning machine, electrospinning prepares spinning fibers, and the resulting spinning fibers are heat-treated to carbonize them to form an aluminum-carbon composite material coated with carbon nanofibers.
  • the present invention provides a negative electrode, including: a current collector and a negative electrode material layer, where the negative electrode material layer is an aluminum-carbon composite material with a thin film structure prepared by the foregoing preparation method.
  • the negative electrode provided by the present invention has all the advantages of the aluminum-carbon composite material described above, and will not be repeated here.
  • the negative electrode provided by the invention is prepared by using the aluminum-carbon composite material, and has the advantages of high coulombic efficiency, less irreversible capacity loss and good cycle stability.
  • the method for preparing the negative electrode includes the following steps:
  • Electrostatic spinning solution is obtained after mixing microcapsule suspension and binder uniformly;
  • the compatibility between the nano aluminum and the binder is increased, and the dispersibility of the nano aluminum in the electrospinning solution is improved, thereby obtaining a uniformly dispersed electrospinning solution;
  • the present invention provides a secondary battery including the negative electrode.
  • the secondary battery provided by the present invention includes a positive electrode, a negative electrode, a separator and an electrolyte interposed between the positive electrode and the negative electrode.
  • the secondary battery provided by the invention is prepared by using the above-mentioned negative electrode, so it also has the advantages of high Coulomb efficiency, less irreversible capacity loss and good cycle stability.
  • the secondary battery in the present invention may be a single ion battery or a dual ion battery.
  • the single ion battery system can be, for example, lithium ion battery, sodium ion battery, potassium ion battery, and can also be used in the dual ion battery system of metal alloying reaction, especially suitable for the battery system of aluminum metal reaction, for example based on lithium Ionized dual ion batteries, various aluminum ion batteries, etc.
  • the present invention provides an electric device including the secondary battery.
  • the electrical equipment may be, for example, an electronic device, a power tool, an electric vehicle, or a power storage system.
  • the secondary battery in the embodiment of the present invention has better cycle stability and higher Coulomb efficiency effect. The same effect can also be obtained in an electronic device, a power tool, an electric vehicle, and a power storage system using the battery of the embodiment of the present invention.
  • the electronic device is an electronic device that uses a lithium ion battery as a power source for operation to perform various functions (for example, playing music).
  • a power tool is a power tool that uses a lithium ion battery as a driving power source to move moving parts (for example, a drill bit).
  • the electric vehicle is an electric vehicle that runs on a lithium ion battery as a driving power source, and may be an automobile (including a hybrid vehicle) equipped with other driving sources in addition to the lithium ion battery.
  • the power storage system is a power storage system that uses a lithium ion battery as a power storage source.
  • a lithium ion battery used as a power storage source
  • the power stored in the lithium ion battery is consumed as necessary to be able to use various devices such as home electronic products.
  • This embodiment is a negative electrode containing an aluminum-carbon composite material, and its preparation method includes the following steps:
  • the compatibility between the nano aluminum and the binder is increased, and the dispersibility of the nano aluminum in the electrospinning solution is improved, thereby obtaining a uniformly dispersed electrospinning solution;
  • Examples 2 to 18 are respectively a negative electrode containing an aluminum-carbon composite material.
  • the preparation method and process are different from those in Example 1 in that the binder used in preparing the electrospinning solution is different.
  • Example 1 is the same.
  • the binders used in Examples 2 to 18 are listed in Table 1.
  • Example 19 is a negative electrode containing an aluminum-carbon composite material.
  • the preparation method and process are different from Example 1 in that the microcapsule film-forming agent used in preparing the electrospinning solution is different, and the others are different from the example. 1 is the same.
  • the microcapsule film-forming agent used in this example is divinylbenzene.
  • Examples 20 to 36 are respectively a negative electrode containing an aluminum-carbon composite material.
  • the preparation method and process are different from those in Example 19 in that the binder used in preparing the electrospinning solution is different.
  • Example 19 is the same.
  • the binders used in Examples 20 to 36 are listed in Table 2.
  • Examples 37 to 40 are respectively a negative electrode containing an aluminum-carbon composite material.
  • the preparation method and process are different from that of Example 1 in that the microcapsule film-forming agent used in preparing the electrospinning solution is different. Same as Example 1. Specifically, the microcapsule film-forming agents used in Examples 37 to 40 are listed in Table 3.
  • This embodiment is a negative electrode containing an aluminum-carbon composite material, and its preparation method includes the following steps:
  • This comparative example is a negative electrode, which is aluminum foil.
  • This comparative example is a negative electrode, the structure of which is a porous aluminum foil and a carbon film formed on the surface of the porous aluminum foil by physical vapor deposition.
  • the negative electrodes provided in Examples 1-41 and Comparative Examples 1-2 were used to prepare dual-ion lithium batteries, respectively, and then the capacity retention rate and coulombic efficiency of each group of batteries after 600 charge and discharge cycles were tested. The test results are listed in Table 4-5.
  • the preparation process of the dual ion lithium battery is as follows:
  • A1 Preparation of positive electrode: Add 0.8g of expanded graphite, 0.1g of carbon black, 0.1g of polyvinylidene fluoride to 2ml of N-methylpyrrolidone solution, fully grind to obtain a uniform slurry; then apply the slurry evenly on the surface of carbon-coated aluminum foil (That is, the positive electrode current collector) and vacuum drying; the dried electrode sheet is cut into a 10 mm diameter disc, which is used as the battery positive electrode after compaction;
  • the glass fiber film is cut into 16mm diameter discs and used as a diaphragm;
  • A4) Battery assembly In an inert gas-protected glove box, the above-mentioned prepared positive electrode, separator, and negative electrode are closely stacked in sequence, and the electrolyte is added dropwise to completely infiltrate the separator. Complete battery assembly.
  • Table 4 contains the performance test results of the battery of the negative electrode in Examples 1-36
  • the type of binder in the electrospinning process has a greater impact on the performance of the resulting battery.
  • the binder is PVP, PAN, or GA
  • the resulting battery has a higher capacity retention rate and Coulomb efficiency after 600 charge-discharge cycles.
  • microcapsule film-forming agents also have a certain effect on the performance of the resulting battery.
  • divinylbenzene was used as the microcapsule film-forming agent, the capacity retention rate and coulombic efficiency of the resulting battery showed an overall upward trend.
  • Table 5 contains the performance test results of the batteries with negative electrodes in Examples 37-41
  • microcapsule film-forming agents also have a certain influence on the performance of the resulting battery.
  • styrene and divinylbenzene are used as the microcapsule film-forming agent, the capacity retention rate and coulombic efficiency of the resulting battery are better.
  • the negative electrode provided by the present invention has a greater cycle performance than the conventional aluminum foil or carbon-coated aluminum foil. Promote.

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Abstract

一种铝碳复合材料及其制备方法、负极、二次电池和用电设备，该铝碳复合材料包括铝纳米颗粒（11）和碳纳米纤维（10），所述铝纳米颗粒（11）包覆于碳纳米纤维（10）内。利用该铝碳复合材料能够缓解现有技术中利用铝箔作为负极时，铝箔在充放电过程中由于体积膨胀造成的粉化的技术问题，提高利用铝作为负极时电池的稳定性。

Description

铝碳复合材料及其制备方法、负极、二次电池和用电设备 技术领域
本发明涉及电池技术领域，尤其是涉及一种铝碳复合材料及其制备方法、负极、二次电池和用电设备。
背景技术
随着便携式电子产品、电动汽车、航天航空等领域的快速发展，开发价格低廉、自然丰度、电化学性能优良的电极材料迫在眉睫。现有已经商业化或者有商业化前景的锂离子电池负极材料包括石墨负极、硅负极以及锂金属负极和铝箔负极等。其中石墨负极是商业化负极材料，其理论容量较低，仅372mAh/g；硅负极材料的容量虽然高，但是其导电性较差，不能同时充当集流体和负极材料。而锂金属负极虽然容量高并且导电性好，但是其充放电机理为锂的溶解-沉积机理，因易生长枝晶而具有潜在安全性问题，同时锂资源储量非常有限，导致在使用过程中成本不断攀升。
基于金属铝负极的新型高效电池体系电池具有比能量密度更高、成本更低的优点，但是单纯的铝箔作为负极时存在如下问题导致其循环性有待进一步提升：(1)锂离子与铝金属合金化过程中表现出显著的体积膨胀，造成电极粉化从而引起电池容量衰减；(2)金属铝与电解液在界面发生反应形成的固体电解质界面层(SEI膜)随时间不断增厚，界面阻抗不断增加，从而使得电池容量衰减；(3)由于铝金属负极体积在充放电过程中不断变化，SEI膜不稳定，在脱嵌锂过程中，不断的生成-破裂-再生成，从而持续消耗锂离子电解液，导致库伦效率降低。针对铝金属负极的这些问题，现有的解决方案包括电解液改性以及碳包覆铝箔的方法。其中铝箔的多孔化和碳包覆共同作用可以在一定程度上解决铝负极存在的问题。但是作为保护层，宏观的碳包覆在铝负极体积膨胀过程中也会有一定程度的破裂，从而无法有效改善体积膨胀以及不稳定SEI膜引起的容量衰减问题。
发明内容
本发明的第一目的在于提供一种铝碳复合材料，以缓解至少上述所提及技 术问题中的一个。
本发明的第二目的在于提供一种铝碳复合材料的制备方法，利用该方法可以得到结构强韧的铝碳复合材料。
本发明的第三目的在于提供一种负极，该负极包括所述铝碳复合材料。
本发明的第四目的在于提供一种二次电池，包括所述负极。
本发明的第五目的在于提供一种用电设备，包括所述二次电池。
为了实现本发明的上述目的，特采用以下技术方案：
一种铝碳复合材料，包括铝纳米颗粒和碳纳米纤维，所述铝纳米颗粒包覆于所述碳纳米纤维内。
一种铝碳复合材料的制备方法，提供含铝纳米颗粒的静电纺丝溶液，利用静电纺丝工艺制备纺丝纤维，所述纺丝纤维经碳化后得到所述铝碳复合材料。
一种负极，包括：集流体和负极材料层，所述负极材料层为利用上述制备方法制备得到的薄膜结构的铝碳复合材料。
一种二次电池，包括所述负极。
一种用电设备，包括所述二次电池。
与已有技术相比，本发明具有如下有益效果：
本发明提供的铝碳复合材料，是将铝纳米颗粒包覆于碳纳米纤维内，当铝纳米颗粒发生体积膨胀时更容易沿着碳纳米纤维的长度方向膨胀。而碳纳米纤维在其长度方向的连接强度又远高于其径向方向的强度，因此，利用碳纳米纤维包覆铝纳米颗粒可以有效提高铝碳复合材料结构的稳定性。
具体的，本发明提供铝碳复合材料具备以下优点：
(1)包覆于铝纳米颗粒表面的碳纳米纤维作为保护碳层能有效使铝纳米颗粒与电解液隔离，防止铝纳米颗粒受到侵蚀；
(2)铝纳米颗粒大大增加了反应的比表面积，为合金化和吸附提供更多反应活性位点，能显著提高电池的倍率性能；
(3)铝纳米化形成铝纳米颗粒后会有效缓解体积变化导致的粉化问题，同时碳纳米纤维包覆层的抑制作用也在很大程度上缓解了铝的膨胀，进而抑制铝在体积变化过程中的粉化，并且保证了铝碳复合结构的完整性，进而提高电池的循环能力；
(4)碳纳米纤维的包覆有利于在电极表面形成稳定的SEI膜，从而提高负极与电解液的界面的稳定性；
(5)碳纳米纤维包覆铝纳米颗粒后，可有效阻止铝的氧化，保持铝纳米颗粒的活性。
本发明提供的负极利用上述铝碳复合材料制备而成，具有库伦效率高，不可逆容量损失少和循环稳定性好的优点。
本发明提供的二次电池，利用上述负极制备而成，因此也具有库伦效率高，不可逆容量损失少和循环稳定性好的优点。
附图说明
图1为本发明一种实施方式的铝碳复合材料的结构示意图。
图标：10-碳纳米纤维；11-铝纳米颗粒。
具体实施方式
下面将结合实施例对本发明的实施方案进行详细描述，但是本领域技术人员将会理解，下列实施例仅用于说明本发明，而不应视为限制本发明的范围。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。
需要说明的是：
本发明中，如果没有特别的说明，本文所提到的所有实施方式以及优选实施方法可以相互组合形成新的技术方案。
本发明中，如果没有特别的说明，本文所提到的所有技术特征以及优选特征可以相互组合形成新的技术方案。
本发明中，如果没有特别的说明，百分数(％)或者份指的是相对于组合物的重量百分数或重量份。
本发明中，如果没有特别的说明，所涉及的各组分或其优选组分可以相互组合形成新的技术方案。
本发明中，除非有其他说明，数值范围“a～b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“6～22”表示本文中已经全部列出了“6～22”之间的全部实数，“6～22”只是这些数值组合的缩略表示。
本发明所公开的“范围”以下限和上限的形式，可以分别为一个或多个下限，和一个或多个上限。
本发明中，除非另有说明，各个反应或操作步骤可以顺序进行，也可以按照顺序进行。优选地，本文中的反应方法是顺序进行的。
除非另有说明，本文中所用的专业与科学术语与本领域熟练人员所熟悉的意义相同。此外，任何与所记载内容相似或均等的方法或材料也可应用于本发明中。
一方面，本发明提供了一种铝碳复合材料，包括铝纳米颗粒和碳纳米纤维，铝纳米颗粒包覆于碳纳米纤维内。
本发明提供的铝碳复合材料，是将铝纳米颗粒包覆于碳纳米纤维内，当铝 纳米颗粒发生体积膨胀时更容易沿着碳纳米纤维的长度方向膨胀。而碳纳米纤维在其长度方向的连接强度又远高于其径向方向的强度，因此，利用碳纳米纤维包覆铝纳米颗粒可以有效提高铝碳复合材料结构的稳定性。
具体的，本发明提供铝碳复合材料具备以下优点：
(1)包覆于铝纳米颗粒表面的碳纳米纤维作为保护碳层能有效使铝纳米颗粒与电解液隔离，防止铝纳米颗粒受到侵蚀；
(2)铝纳米颗粒大大增加了反应的比表面积，为合金化和吸附提供更多反应活性位点，能显著提高电池的倍率性能；
(3)铝纳米化形成铝纳米颗粒后会有效缓解体积变化导致的粉化问题，同时碳纳米纤维包覆层的抑制作用也在很大程度上缓解了铝的膨胀，进而抑制铝在体积变化过程中的粉化，并且保证了铝碳复合结构的完整性，进而提高电池的循环能力；
(4)碳纳米纤维的包覆有利于在电极表面形成稳定的SEI膜，从而提高负极与电解液的界面的稳定性；
(5)碳纳米纤维包覆铝纳米颗粒后，可有效阻止铝的氧化，保持铝纳米颗粒的活性。
其中，本发明一种实施方式的铝碳复合材料的结构如图1所示，包括碳纳米纤维10和包覆于碳纳米纤维内的铝纳米颗粒11。
在本发明的一些实施方式中，所述铝纳米颗粒的粒径为5～100nm，优选为10～100nm。
通过优化铝纳米颗粒的粒径，可以进一步提升铝碳复合材料结构的稳定性。其中，铝纳米颗粒的粒径典型但非限制性的例如为5nm、10nm、20nm、30nm、40nm、50nm、60nm、70nm、80nm、90nm或100nm。
在本发明的一些实施方式中，所述碳纳米纤维的直径为100～2000nm，优选为300～1000nm。
通过优化碳纳米纤维的直径，既可以保证碳纳米纤维对铝纳米颗粒的包覆，又可以保证碳纳米纤维的抗拉强度。
其中，碳纳米纤维的直径典型但非限制性的例如可以为100nm、200nm、300nm、400nm、500nm、600nm、700nm、800nm、900nm、1000nm、1200nm、1400nm、1600nm、1800nm或2000nm。
在本部发明的一些实施方式中，所述铝纳米颗粒占所述铝碳复合材料的质量的10％～85％，优选为50％～70％。
通过优化铝纳米颗粒的占比，既可以保证铝纳米颗粒作为负极活性材料时具有较高的容量，又可以保证铝碳复合材料结构的稳定性。
第二方面，本发明提供了一种铝碳复合材料的制备方法，提供含铝纳米颗粒的静电纺丝溶液，利用静电纺丝工艺制备纺丝纤维，所述纺丝纤维经碳化后得到所述铝碳复合材料。
利用该方法得到的铝碳复合材料具有上述铝碳复合材料的全部优点，在此不再赘述。
利用静电纺丝工艺制备铝碳复合材料，通过控制静电纺丝溶液的浓度和均匀度等，可以有效控制铝碳复合材料的尺寸以及铝纳米颗粒含量，使制备得到的铝碳复合材料的各项尺寸符合使用要求。
在本发明的一些实施方式中，静电纺丝溶液的制备方法包括：将铝纳米颗粒溶于含有微胶囊成膜剂的溶液中，混合均匀后得到微胶囊悬浮液，然后再将所述微胶囊悬浮液与所述粘结剂混合均匀后得到静电纺丝溶液，其中粘结剂与铝纳米颗粒的质量比例如可以为1:1～10:1。
先利用微胶囊成膜剂对铝纳米颗粒进行包覆，形成具有核壳结构的微胶囊，微胶囊结构有利于铝纳米颗粒在粘结剂中均匀分散，从而形成稳定且均匀的静电纺丝溶液。
其中，所述静电纺丝溶液中的溶剂例如可以为醇类溶剂和醚类溶剂的混合溶剂；醇类溶剂典型但非限制性的为甲醇、乙醇、苯甲醇或乙二醇中至少一种；醚类溶剂典型但非限制性的为甲醚、甲乙醚、乙醚、正丙醚或正丁醚中的至少一种。
在本发明的一些实施方式中，先用表面活性剂对铝纳米颗粒进行表面处理，使铝纳米颗粒表面的电性与微胶囊成膜剂的电性相反，微胶囊成膜剂与铝纳米颗粒的质量比例如可以为1:1～10:1，再将经过表面处理的铝颗粒分散于含有微胶囊成膜剂的溶液中，通过表面活性剂与微胶囊成膜剂之间的静电吸附，原位聚合包覆所述铝纳米颗粒，形成所述微胶囊悬浮液。
通过对铝纳米颗粒进行表面处理，使铝纳米颗粒与微胶囊成膜剂表面分别带有不同电性的电荷，利用异形相吸使微胶囊成膜剂吸附在铝纳米颗粒表面，进而在铝纳米颗粒表面形成包覆层，成为微胶囊结构。得到的微胶囊悬浮液中微胶囊的粒径例如可以为10～300nm。
例如，可以利用以下方法对对铝纳米颗粒进行表面处理：
将铝纳米颗粒溶于表面活性剂中，对铝纳米颗粒表面进行修饰，使铝纳米颗粒表面带有相应的电荷，同时显著降低铝颗粒表面张力。
其中，表面活性剂包括离子型表面活性剂，例如可以为硬脂酸、十二烷基苯磺酸钠、季铵化物、卵磷脂、氨基酸型或甜菜碱型中的至少一种，优选为硬脂酸或十二烷基磺酸钠。
在本发明的一些实施方式中，所述微胶囊成膜剂包括苯乙烯或二乙烯基苯。 利用苯乙烯或二乙烯基苯作为成膜剂时，苯乙烯或二乙烯基苯可以在与铝纳米颗粒接触后会在铝纳米颗粒的表面发生原位聚合，从而在铝纳米颗粒表面形成均匀的包覆层。
需要说明的是，本发明中的微胶囊成膜剂除了苯乙烯和二乙烯基苯外还可以为其他的成膜剂，例如明胶、阿拉伯胶、虫胶、紫胶、淀粉、糊精、蜡、松脂、海藻酸钠、玉米朊、壳聚糖、聚丁二烯、聚丙烯、聚醚、聚脲、聚乙二醇、聚乙烯醇、聚酰胺、聚丙烯酰胺、聚氨酯、聚甲基丙烯酸甲酯、聚乙烯吡咯烷酮、环氧树脂或聚硅氧烷等天然天然高分子材料或合成高分子材料构成。
在本发明的一些实施方式中，所述粘结剂包括糖类粘结剂、海藻酸盐类粘结剂、羧甲基纤维素盐类粘结剂或聚烯烃类粘结剂中的至少一种。
具体的，所述粘结剂典型但非限制性的包括阿拉伯树胶(简称为GA)、海藻酸钠(Sodium alginate)、羧甲基纤维素钠(简称为CMC)、聚乙烯吡咯烷酮(简称为PVP)、聚丙烯腈(简称为PAN)、聚偏氟乙烯(简称为PVDF)、聚四氟乙烯(简称为PTFE)、聚乙烯醇(简称为PVA)、聚丙烯酸(简称为PAA)、聚丙烯酸铵(简称为PAA-NH 4)、醋酸乙烯树脂(简称为PVAc)、聚丙烯酸-聚乙烯醇共聚物(简称为PAA-PVA)、聚乙烯醇-聚乙烯亚胺共聚物(简称为PVA-PEI)、聚丙烯酸-羧甲基纤维素钠共聚物(简称为PAA-CMC)、聚丙烯酸钠接枝羧甲基纤维素钠(简称为NaPPA-g-CMC)、聚丙烯酸二烯丙基醚(简称为PAA-Dially ether)、羰基环糊精(简称为C-CDP)或阿拉伯树胶-聚丙烯酸共聚物(简称为GA-PAA)聚烯烃类中的至少一种。
在本发明的一些实施方式中，铝碳复合材料的制备方法包括以下步骤：
A)将微胶囊成膜剂溶解于溶剂中，混合均匀后得到混合溶液；
B)颗粒粒径为5～100nm的铝纳米颗粒经表面改性后作为核体加入到所述混合溶液中，然后在氮气保护下使微胶囊成膜剂均匀包覆于铝纳米颗粒表面形成核壳结构的微胶囊悬浮液；
C)将微胶囊悬浮液与粘结剂混合均匀后得到静电纺丝溶液；
通过制备微胶囊增大了纳米铝与粘结剂之间的相容性，提高了纳米铝在静电纺丝溶液中的分散性，从而得到分散均匀的静电纺丝溶液；
D)将所得的静电纺丝溶液加入到静电纺丝机中，静电纺丝制备纺丝纤维，对所得纺丝纤维进行热处理使其发生碳化，形成碳纳米纤维包覆的铝碳复合材料。
第三方面，本发明提供了一种负极，包括：集流体和负极材料层，所述负极材料层为利用上述制备方法制备得到的薄膜结构的铝碳复合材料。
本发明提供的负极具有上述铝碳复合材料的全部优点，在此不再赘述。
本发明提供的负极利用上述铝碳复合材料制备而成，具有库伦效率高，不可逆容量损失少和循环稳定性好的优点。
在本发明的一些实施方式中，所述负极的制备方法包括以下步骤：
A)将微胶囊成膜剂溶解于溶剂中，混合均匀后得到混合溶液；
B)颗粒粒径为5～100nm的铝纳米颗粒经表面改性后作为核体加入到所述混合溶液中，然后在氮气保护下使微胶囊成膜剂均匀包覆于铝纳米颗粒表面形成核壳结构的微胶囊悬浮液；
C)将微胶囊悬浮液与粘结剂混合均匀后得到静电纺丝溶液；
通过制备微胶囊增大了纳米铝与粘结剂之间的相容性，提高了纳米铝在静电纺丝溶液中的分散性，从而得到分散均匀的静电纺丝溶液；
D)将所得的静电纺丝溶液加入到静电纺丝机中，以集流体为载体，在集流体上静电纺丝制备纺丝纤维薄膜，对所得纺丝纤维进行热处理使其发生碳化，得到所述负极。
第四方面，本发明提供了一种二次电池，包括所述负极。
具体的，本发明提供的二次电池包括正极、负极以及介于正极与负极之间的隔膜和电解液。
本发明提供的二次电池，利用上述负极制备而成，因此也具有库伦效率高，不可逆容量损失少和循环稳定性好的优点。
本发明中的二次电池，可以为单离子电池也可以为双离子电池。
其中，单离子电池体系例如可以锂离子电池，钠离子电池，钾离子电池，还可以用于金属合金化反应的双离子电池体系中，尤其适用于于铝金属反应的电池体系中，例如基于锂离子的双离子电池，各种铝离子电池等等。
第五方面，本发明提供了一种用电设备，包括所述的二次电池。
其中，用电设备例如可以为电子装置、电动工具、电动车辆、电力储存系统。在本发明实施方式的二次电池具有较好的循环稳定性和较高的库伦效率效果。在使用本发明实施方式的电池的电子装置、电动工具、电动车辆、以及电力储存系统中也可以获得相同的效果。
其中，电子装置是使用锂离子电池作为操作的电源执行各种功能(例如，演奏音乐)的电子装置。
电动工具是使用锂离子电池作为驱动电源来移动移动部件(例如，钻头)的电动工具。
电动车辆是依靠锂离子电池作为驱动电源运行的电动车辆，并且可以是除了锂离子电池之外还装备有其他驱动源的汽车(包括混合动力车)。
电力储存系统是使用锂离子电池作为电力储存源的电力储存系统。例如，在家用电力储存系统中，使电力储存在用作电力储存源的锂离子电池中，并且 根据需要消耗储存在锂离子电池中的电力以能够使用诸如家用电子产品的各种装置。
下面将结合实施例和对比例对本发明做进一步详细的说明。
实施例1
本实施例是一种包含铝碳复合材料的负极，其制备方法包括以下步骤：
S1)将微胶囊成膜剂苯乙烯溶解于体积比为1：1的乙醇和乙醚的混合溶剂中，混合均匀后得到混合溶液；
S2)将经硬脂酸表面改性的颗粒粒径为5～100nm的铝纳米颗粒作为核体加入到所述混合溶液中，然后在氮气保护下使苯乙烯均匀包覆于铝纳米颗粒表面形成核壳结构的微胶囊悬浮液；其中，苯乙烯与铝纳米颗粒的质量比为8:1；
S3)将微胶囊悬浮液与粘结剂PVP混合均匀后得到静电纺丝溶液；其中，粘结剂与铝纳米颗粒的质量比为9:1；
通过制备微胶囊增大了纳米铝与粘结剂之间的相容性，提高了纳米铝在静电纺丝溶液中的分散性，从而得到分散均匀的静电纺丝溶液；
S4)将所得的静电纺丝溶液加入到静电纺丝机中，以铜箔集流体作为接受基底进行静电纺丝，在铜箔集流体上得到分布均一的纺丝纤维薄膜，对所得纺丝纤维进行热处理使其发生碳化在铜箔集流体表面得到铝碳复合材料构成的薄膜，得到电极片，对所得电极片裁切成直径12mm的圆片，压实后作为负极备用。
实施例2～18
实施例2～18分别是一种包含铝碳复合材料的负极，其制备方法与过程与实施例1相比不同之处在于，在制备静电纺丝溶液时使用的粘结剂不同，其他与实施例1均相同。具体的，实施例2～18中所用的粘结剂列于表1。
表1
序号 粘结剂 微胶囊成膜剂
实施例1 PVP 苯乙烯
实施例2 PAN 苯乙烯
实施例3 PVDF 苯乙烯
实施例4 PTFE 苯乙烯
实施例5 PVA 苯乙烯
实施例6 Sodium alginate 苯乙烯
实施例7 CMC 苯乙烯
实施例8 PAA 苯乙烯
实施例9 PAA-NH 4 苯乙烯
实施例10 PVAc 苯乙烯
实施例11 PAA-PVA 苯乙烯
实施例12 PVA-PEI 苯乙烯
实施例13 PAA-CMC 苯乙烯
实施例14 NaPPA-g-CMC 苯乙烯
实施例15 PAA-Dially ether 苯乙烯
实施例16 C-CDP 苯乙烯
实施例17 GA 苯乙烯
实施例18 GA-PAA 苯乙烯
实施例19
实施例19是一种包含铝碳复合材料的负极，其制备方法与过程与实施例1相比不同之处在于，在制备静电纺丝溶液时使用的微胶囊成膜剂不同，其他与实施例1均相同。本实施例中所使用的微胶囊成膜剂为二乙烯基苯。
实施例20～36
实施例20～36分别是一种包含铝碳复合材料的负极，其制备方法与过程与实施例19相比不同之处在于，在制备静电纺丝溶液时使用的粘结剂不同，其他与实施例19均相同。具体的，实施例20～36中所用的粘结剂列于表2。
表2
序号 粘结剂 微胶囊成膜剂
实施例19 PVP 二乙烯基苯
实施例20 PAN 二乙烯基苯
实施例21 PVDF 二乙烯基苯
实施例22 PTFE 二乙烯基苯
实施例23 PVA 二乙烯基苯
实施例24 Sodium alginate 二乙烯基苯
实施例25 CMC 二乙烯基苯
实施例26 PAA 二乙烯基苯
实施例27 PAA-NH 4 二乙烯基苯
实施例28 PVAc 二乙烯基苯
实施例29 PAA-PVA 二乙烯基苯
实施例30 PVA-PEI 二乙烯基苯
实施例31 PAA-CMC 二乙烯基苯
实施例32 NaPPA-g-CMC 二乙烯基苯
实施例33 PAA-Dially ether 二乙烯基苯
实施例34 C-CDP 二乙烯基苯
实施例35 GA 二乙烯基苯
实施例36 GA-PAA 二乙烯基苯
实施例37～40
实施例37～40分别是一种包含铝碳复合材料的负极，其制备方法与过程与实施例1相比不同之处在于，在制备静电纺丝溶液时使用的微胶囊成膜剂不 同，其他与实施例1均相同。具体的，实施例37～40中所用的微胶囊成膜剂列于表3。
表3
序号 粘结剂 微胶囊成膜剂
实施例1 PVP 苯乙烯
实施例19 PVP 二乙烯基苯
实施例37 PVP 明胶
实施例38 PVP 阿拉伯胶
实施例39 PVP 甲基丙烯酸甲酯
实施例40 PVP 醋酸纤维素
实施例41
本实施例是一种包含铝碳复合材料的负极，其制备方法包括以下步骤：
S1)提供体积比为1：1的乙醇和乙醚的混合溶剂，然后将经硬脂酸改性的颗粒粒径为5～100nm的铝纳米颗粒作为核体加入到所述混合溶剂中，得到铝纳米颗粒悬浮液；
S2)将铝纳米颗粒悬浮液与粘结剂PVP混合均匀后得到静电纺丝溶液；其中，粘结剂与铝纳米颗粒的质量比为9:1；
S3)将所得的静电纺丝溶液加入到静电纺丝机中，以铜箔集流体作为接受基底进行静电纺丝，在铜箔集流体上得到分布均一的纺丝纤维薄膜，对所得纺丝纤维进行热处理使其发生碳化在铜箔集流体表面得到铝碳复合材料构成的薄膜，得到电极片，对所得电极片裁切成直径12mm的圆片，压实后作为负极备用。
对比例1
本对比例是一种负极，为铝箔。
对比例2
本对比例是一种负极，其结构为多孔铝箔和利用物理气相沉积法形成于多孔铝箔表面的碳膜。
分别利用实施例1-41和对比例1-2提供的负极制备双离子锂电池，然后测试各组电池充放电循环600次后的容量保持率和库伦效率。测试结果列于表4-5。
具体的，双离子锂电池的制备过程如下：
A1)制备正极：将0.8g膨胀石墨、0.1g碳黑、0.1g聚偏氟乙烯加入到2ml氮甲基吡咯烷酮溶液中，充分研磨获得均匀浆料；然后将浆料均匀涂覆于涂炭铝箔表面(即正极集流体)并真空干燥；对干燥所得电极片裁切成直径10mm的圆片，压实后作为电池正极备用；
A2)制备隔膜：将玻璃纤维薄膜裁切成直径16mm的圆片后作为隔膜备用；
A3)配制电解液：称取3g六氟磷酸锂加入到5ml碳酸亚乙烯酯和碳酸甲乙酯的混合溶剂中，溶解、混合均匀后作为电解液备用；
A4)电池组装：在惰性气体保护的手套箱中，将上述制备好的正极、隔膜、负极依次紧密堆叠，滴加电解液使隔膜完全浸润，然后将上述堆叠部分封装入扣式电池壳体，完成电池组装。
表4包含实施例1-36中负极的电池的性能测试结果
Figure PCTCN2019123480-appb-000001
Figure PCTCN2019123480-appb-000002
从表4中的数据可以看出，静电纺丝过程中的粘结剂的种类对最终得到的电池的性能有较大的影响。当粘结剂为PVP、PAN或GA时，得到的电池在充放电循环600次后，容量保持率和库伦效率较高。
另外，不同的微胶囊成膜剂对最终得到的电池的性能也有一定的影响。当微胶囊成膜剂采用二乙烯基苯时，得到的电池的容量保持率和库伦效率整体上呈上升趋势。
表5包含实施例37-41中负极的电池的性能测试结果
Figure PCTCN2019123480-appb-000003
Figure PCTCN2019123480-appb-000004
从表5中数据可以看出，不同的微胶囊成膜剂对最终得到的电池的性能也有一定的影响。当微胶囊成膜剂采用苯乙烯和二乙烯基苯时，得到的电池的容量保持率和库伦效率较好。
另外，从实施例1-40与实施例41的对比数据可以看出，在制备静电纺丝溶液时，先制备出铝纳米微胶囊，可以显著提高最终得到的电池的循环性能。
再者，从实施例1-41以及对比例1-2的对比数据可以看出，本发明提供的负极相比于传统的铝箔或碳包覆铝箔，最终得到的电池的循环性能也有很大的提升。
以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。

Claims (18)

  1. 一种铝碳复合材料，其特征在于，包括铝纳米颗粒和碳纳米纤维，所述铝纳米颗粒包覆于所述碳纳米纤维内。
  2. 根据权利要求1所述的铝碳复合材料，其特征在于，所述铝纳米颗粒的粒径为5～100nm；所述碳纳米纤维的直径为100～2000nm；所述铝纳米颗粒占所述铝碳复合材料的质量的10％～85％。
  3. 根据权利要求1所述的铝碳复合材料，其特征在于，所述铝纳米颗粒的粒径为10～100nm；所述碳纳米纤维的直径为300～1000nm；所述铝纳米颗粒占所述铝碳复合材料的质量的50％～70％。
  4. 一种权利要求1或2所述的铝碳复合材料的制备方法，其特征在于，提供含铝纳米颗粒的静电纺丝溶液，利用静电纺丝工艺制备纺丝纤维，所述纺丝纤维经碳化后得到所述铝碳复合材料。
  5. 根据权利要求4所述的制备方法，其特征在于，所述静电纺丝溶液的制备方法包括：将铝纳米颗粒溶于含有微胶囊成膜剂的溶液中，混合均匀后得到微胶囊悬浮液，然后再将所述微胶囊悬浮液与粘结剂混合，混合均匀后得到静电纺丝溶液。
  6. 根据权利要求5所述的制备方法，其特征在于，所述静电纺丝溶液的制备方法包括：先用表面活性剂对铝纳米颗粒进行表面处理，使铝纳米颗粒表面的电性与微胶囊成膜剂的电性相反，再将经过表面处理的铝颗粒分散于含有微胶囊成膜剂的溶液中，通过表面活性剂与微胶囊成膜剂之间的静电吸附，原位聚合包覆所述铝纳米颗粒，形成所述微胶囊悬浮液。
  7. 根据权利要求6所述的制备方法，其特征在于，所述表面活性剂包括离子 型表面活性剂。
  8. 根据权利要求7所述的制备方法，其特征在于，所述表面活性剂为硬脂酸、十二烷基苯磺酸钠、季铵化物、卵磷脂、氨基酸型或甜菜碱型中的至少一种。
  9. 根据权利要求8所述的制备方法，其特征在于，微胶囊成膜剂与铝纳米颗粒的质量比为1:1～10:1；粘结剂与铝纳米颗粒的质量比为1:1～10:1。
  10. 根据权利要求9所述的制备方法，其特征在于，所述微胶囊成膜剂包括苯乙烯和/或二乙烯基苯。
  11. 根据权利要求10所述的制备方法，其特征在于，所述微胶囊悬浮液中微胶囊的粒径为10～300nm。
  12. 根据权利要求5所述的制备方法，其特征在于，所述粘结剂包括糖类粘结剂、海藻酸盐类粘结剂、羧甲基纤维素盐类粘结剂或聚烯烃类粘结剂中的至少一种。
  13. 根据权利要求12所述的制备方法，其特征在于，所述粘结剂包括阿拉伯树胶、海藻酸钠、羧甲基纤维素钠、聚乙烯吡咯烷酮、聚丙烯腈、聚偏氟乙烯、聚四氟乙烯、聚乙烯醇、聚丙烯酸、聚丙烯酸铵、醋酸乙烯树脂、聚丙烯酸-聚乙烯醇共聚物、聚乙烯醇-聚乙烯亚胺共聚物、聚丙烯酸-羧甲基纤维素钠共聚物、聚丙烯酸钠接枝羧甲基纤维素钠、聚丙烯酸二烯丙基醚、羰基环糊精、阿拉伯树胶-聚丙烯酸共聚物聚烯烃类中的至少一种。
  14. 根据权利要求5所述的制备方法，其特征在于，所述纺丝溶液中的溶剂为醇类溶剂和醚类溶剂的混合溶剂。
  15. 根据权利要求14所述的制备方法，其特征在于，所述醇类溶剂包括甲醇、乙醇、苯甲醇或乙二醇中至少一种；所述醚类溶剂包括甲醚、甲乙醚、乙醚、正丙醚或正丁醚中的至少一种。
  16. 一种负极，其特征在于，包括：集流体和负极材料层，所述负极材料层为利用权利要求4-15任一项所述的制备方法制备得到的薄膜结构的铝碳复合材料。
  17. 一种二次电池，其特征在于，包括权利要求16所述的负极。
  18. 一种用电设备，其特征在于，包括权利要求17所述的二次电池。
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WO2014160174A9 (en) * 2013-03-14 2014-12-11 Cornell University Carbon and carbon precursors in nanofibers
CN105161698A (zh) * 2015-08-06 2015-12-16 苏州第一元素纳米技术有限公司 一种铝/碳复合电极的制备方法
CN108682802A (zh) * 2018-04-25 2018-10-19 福建翔丰华新能源材料有限公司 一种制备锂电负极用壳-核结构纳米纤维的方法
CN109671932A (zh) * 2018-12-18 2019-04-23 深圳先进技术研究院 铝碳复合材料及其制备方法、负极、二次电池和用电设备

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