WO2015043359A1 - Lithium ion battery anode composite material and preparing method thereof - Google Patents

Lithium ion battery anode composite material and preparing method thereof Download PDF

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WO2015043359A1
WO2015043359A1 PCT/CN2014/085568 CN2014085568W WO2015043359A1 WO 2015043359 A1 WO2015043359 A1 WO 2015043359A1 CN 2014085568 W CN2014085568 W CN 2014085568W WO 2015043359 A1 WO2015043359 A1 WO 2015043359A1
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positive electrode
lithium ion
electrode composite
ion battery
composite material
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French (fr)
Chinese (zh)
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张艳丽
王莉
何向明
赵鹏
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江苏华东锂电技术研究院有限公司
清华大学
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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
    • H01M4/62—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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/582—Halogenides
    • 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
    • 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 a lithium ion battery cathode composite material and a preparation method thereof, in particular to a lithium ion battery cathode composite material comprising ferric fluoride and a preparation method thereof.
  • Ferric fluoride FeF 3
  • FeF 3 Ferric fluoride
  • the combination of the particle size of the iron fluoride and the use of the second phase conductive material as the carrier of the carrier is mainly used to improve the conductivity of the iron fluoride and increase the reaction rate of the electrode kinetics.
  • the particle size reduction can reduce the electron transport path and increase the reaction area, thereby increasing the electrochemical activity of the ferric fluoride.
  • the use of a second phase conductive material as its supporting carrier combines iron fluoride particles with another material having a better electrical conductivity to improve its electrochemical performance.
  • the second phase materials that have been reported so far are: mesoporous carbon, activated carbon spheres, PEDOT, V 2 O 5 , MoS 2 , graphene or carbon nanotubes.
  • carbon nanotubes have unique one-dimensional nanostructures, excellent electron conductivity and thermal conductivity, and low density, and are considered to be ideal materials for improving the conductivity of electrode materials.
  • Korean researchers have prepared a structure in which flower-like ferric fluoride particles are combined with carbon nanotubes, and a surfactant CTAB is used in the preparation process.
  • the surfactant is difficult to remove, resulting in the residual CTAB in the final product, and CTAB will adversely affect the electrochemical performance of the battery electrode material.
  • a lithium ion battery cathode composite material comprising a plurality of ferric fluoride particles and a plurality of carbon nanotubes, wherein the plurality of ferric fluoride particles and the plurality of carbon nanotubes form a three-dimensional conductive network, wherein the plurality of carbons
  • the nanotubes are dispersed between the plurality of ferric fluoride particles, and at least a portion of the iron fluoride particles are connected by the carbon nanotubes.
  • a method for preparing a positive electrode composite material for a lithium ion battery comprising the steps of: providing a carbon nanotube raw material, and an HF solution; dispersing the carbon nanotube raw material in the HF solution to form a first suspension Providing a FeCl 3 solution, and mixing the FeCl 3 solution with the first suspension to obtain a precipitate FeF 3 ⁇ 3H 2 O-CNTs; and separating and purifying the precipitate, and heat treating the A precipitate is obtained to obtain the lithium ion battery positive electrode composite.
  • the FeF 3 -CNTs positive electrode composite material is prepared by combining carbon nanotubes with iron fluoride, adopting a coprecipitation method, and using no surfactant during the reaction.
  • the carbon nanotubes and the ferric fluoride particles form a three-dimensional conductive network, and an electron transport channel is provided during charging and discharging of the battery, so that the FeF 3 -CNTs positive electrode composite material has high conductivity. Therefore, the battery composed of FeF 3 -CNTs positive electrode composite material has higher discharge capacity and better cycle capacity, and has a more obvious charging and discharging platform.
  • FIG. 1 is a flow chart of a method for preparing a positive electrode composite material for a lithium ion battery according to an embodiment of the present invention.
  • Example 2 is a scanning electron micrograph of a FeF 3 -CNTs positive electrode composite material of Example 1 of the present invention.
  • Figure 3 is an XRD diffraction pattern of the intermediate product FeF 3 ⁇ 3H 2 O-CNTs of Example 1 of the present invention.
  • Example 4 is an XRD diffraction pattern of a FeF 3 -CNTs positive electrode composite material of Example 1 of the present invention.
  • Fig. 5 is a graph showing the first charge and discharge test of the FeF 3 -CNTs positive electrode composite material of Example 1 of the present invention at a voltage of 1.0 V to 4.5 V.
  • Fig. 6 is a graph showing the first charge and discharge test of the FeF 3 positive electrode material of Comparative Example 1 at a voltage of 1.0 V to 4.5 V.
  • Fig. 7 is a graph showing a constant current charge and discharge test of the FeF 3 -CNTs positive electrode composite material of Example 1 of the present invention.
  • Fig. 8 is a graph showing the rate discharge curve of the FeF 3 -CNTs positive electrode composite material of Example 1 of the present invention at different power densities.
  • Figure 9 is a graph showing the rate discharge curve of the FeF 3 cathode material of Comparative Example 1 at different current densities.
  • Fig. 10 is a graph showing a comparison of charge and discharge cycle tests of the FeF 3 positive electrode material of Comparative Example 1 and the FeF 3 -CNTs positive electrode composite material of Example 1.
  • an embodiment of the present invention provides a method for preparing a positive electrode composite material for a lithium ion battery, which includes the following steps:
  • the carbon nanotube raw material may be one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, or multi-walled carbon nanotubes.
  • the carbon nanotubes preferably have an inner diameter of 2 nm to 15 nm, an outer diameter of 10 nm to 30 nm, and a length of several hundred micrometers.
  • the carbon nanotube raw material can be prepared by an arc discharge method, a chemical vapor deposition method, or a laser evaporation method.
  • the HF solution is prepared by dissolving HF gas in water, and the mass fraction of HF in the HF solution is 30% to 40%.
  • the carbon nanotube raw material may be dispersed in the HF solution by mechanical stirring or ultrasonic stirring.
  • the carbon nanotube material is uniformly distributed in the HF solution to form the first suspension.
  • the FeCl 3 solution may be prepared by dissolving FeCl 3 ⁇ 6H 2 O particles in a solvent, or by other means.
  • the solvent may be one or more of deionized water, methanol, ethanol, acetone, and diethyl ether.
  • concentration of the FeCl 3 solution is not limited, and may be configured according to the selection of the solvent and actual needs. Since a small amount of fluorine is lost during the reaction, excessive HF can be added to compensate for the loss of fluorine during the reaction.
  • the suspension of the first molar solution of FeCl 3 and FeCl 3 HF concentration is greater than 3: 1, mass ratio of the carbon nanotube feedstock solution with the FeCl 3 FeCl 3 0.007 : 1 to 0.08:1 mixed.
  • the first suspension and the FeCl 3 solution are mixed according to a molar concentration ratio of HF to FeCl 3 of 3.1:1 to 3.2:1.
  • the mass percentage of the carbon nanotubes in the finally prepared lithium ion battery positive electrode composite is 1-10%.
  • the FeCl 3 solution may be dropwise added to the first suspension by dropwise addition to carry out the reaction, and specifically, the dropping acceleration is preferably 5 seconds per drop. Thereby, the fluorine is in an excessive state throughout the reaction, thereby obtaining pure phase FeF 3 .
  • the FeCl 3 solution may also be dropped into another reactor simultaneously with the first suspension to carry out a reaction. During the reaction, Fe 3+ in the FeCl 3 solution and the suspension of the first F - Reaction hydrate FeF 3 ⁇ 3H 2 O precipitates. At the same time, the carbon nanotube raw material may be entangled on the FeF 3 .3H 2 O particles or dispersed between the FeF 3 .3H 2 O particles to form a plurality of conductive channels.
  • the first suspension and the FeCl 3 solution may be sufficiently reacted by mechanical stirring, ultrasonic stirring or magnetic stirring. Further, after the reaction is completed, the mixture may be continuously stirred for 10 to 12 hours to uniformly disperse the precipitate and the carbon nanotube raw material.
  • the precipitate may be separated from the liquid phase by a filtration method to obtain the precipitate.
  • the filtration method may be atmospheric filtration or vacuum filtration.
  • the method of atmospheric filtration specifically includes pouring the mixed solution into a funnel in which filter paper is placed, and allowing to stand for a period of time to obtain the precipitate.
  • the vacuum filtration method specifically includes providing a microporous membrane and an evacuation funnel, pouring the mixed solution into the suction funnel through the microfiltration membrane, suctioning and obtaining a precipitate.
  • a step of washing the precipitate with deionized water and a step of drying the precipitate may be further included. The drying step preferably transfers the precipitate to a blast drying oven and is dried for 8-10 hours at about 60 °C.
  • the heat-treated FeF 3 ⁇ 3H 2 O-CNTs are carried out in an inert atmosphere such as N 2 or Ar, and the heat treatment temperature is 120 ° C - 170 ° C, thereby facilitating the generation of the hetero phase in the positive electrode composite material, and obtaining the pure phase FeF. 3 -CNTs positive electrode composite.
  • the heat treatment temperature is about 125 ° C to 140 ° C.
  • the temperature profile of the sintering may be set to: from room temperature to 120 ° C to 170 ° C; the heating rate may be 3 to 5 ° C / min; the holding time is set to 8 to 12 hours.
  • the 300 mg of carbon nanotubes 40 mL HF (38% by mass percentage) of an aqueous solution, an ultrasonic dispersion to obtain a first suspension 1h; and 40.54 g FeCl 3 .6H 2 O dissolved in 40 mL of deionized water to obtain a solution of FeCl 3; Under magnetic stirring, the FeCl 3 solution was dropped into the first suspension dropwise, and magnetic stirring was continued for 10 h to obtain a mixture containing a precipitate; the mixture was filtered to precipitate the precipitate. The material was dried at 60 ° C for 10 h, and the precipitate was heat-treated in an N 2 atmosphere at 130 ° C for 10 h to obtain a FeF 3 -CNTs positive electrode composite.
  • the 500 mg of carbon nanotubes 100 mL HF (38% by mass percentage) of an aqueous solution, an ultrasonic dispersing 3h to give a first suspension; and 54.058 g FeCl 3 .6H 2 O was dissolved in 100 mL of deionized water to obtain a solution of FeCl 3; Under magnetic stirring, the FeCl 3 solution was dropped into the first suspension dropwise, and magnetic stirring was continued for 10 h to obtain a mixture containing a precipitate; the mixture was filtered to precipitate the precipitate. The material was dried at 60 ° C for 10 h, and the precipitate was heat-treated in a N 2 atmosphere at 140 ° C for 10 h to obtain a FeF 3 -CNTs positive electrode composite.
  • Comparative Example 1 was substantially the same as Example 1, except that no carbon nanotubes were added.
  • the FeF 3 -CNTs positive electrode composite material includes a plurality of iron fluoride particles and a plurality of carbon nanotubes uniformly dispersed between the iron fluoride particles or entangled in the fluorination A three-dimensional conductive network is formed on the iron particles, and the plurality of iron fluoride particles are connected by a plurality of carbon nanotubes, and the plurality of carbon nanotubes form a plurality of conductive channels.
  • the iron fluoride particles are rod-shaped, have a length of 2 micrometers to 6 micrometers, and have a diameter of 100 nanometers to 300 nanometers, and each of the rod-shaped iron fluorides is composed of a plurality of nano-fluorinated iron particles having a diameter of about 30 nm.
  • the diffraction peak position of the FeF 3 -CNTs positive electrode composite obtained in Example 1 completely corresponds to the PDF standard map, and the intensity of each diffraction peak is higher, and the peak shape is higher. Sharp, indicating that the obtained FeF 3 -CNTs positive electrode composite is pure phase, no other impurity phase exists.
  • the FeF 3 -CNTs positive electrode composite materials obtained in Example 1, Example 2, and Example 3, and the FeF 3 positive electrode material obtained in Comparative Example 1 were respectively used as positive electrode materials to constitute a battery for battery performance test.
  • the positive electrode of the test cell includes the following components:
  • the components were thoroughly stirred and mixed to form a slurry, which was applied to the surface of the aluminum foil current collector, and then vacuum dried at 120 ° C for 24 hours.
  • the lithium metal plate was used as the negative electrode, and the Celgard 2400 microporous polypropylene film was used as the separator.
  • the composition was composed of 1 mol/L LiPF 6 /EC+DMC+DEC (1:1:1 volume ratio) as an electrolyte in an argon atmosphere glove box. Button Battery.
  • the battery composed of the FeF 3 -CNTs positive electrode composite material of Example 1 and the FeF 3 positive electrode material of Comparative Example 1 was subjected to charge and discharge test and constant current at a current density of 100 mAg -1 and a range of 1.0 V to 4.5 V, respectively. Charge and discharge test. Referring to FIG.
  • the FeF 3 -CNTs positive electrode composite material of the embodiment 1 has a relatively obvious three-electron charging and discharging platform and has a high discharge capacity, and the first discharge capacity can reach about 600 mAhg -1 ;
  • the three-electron charging and discharging platform of the FeF 3 positive electrode material of Comparative Example 1 is not obvious, and its initial discharge capacity is only about 350 mAhg -1 .
  • the discharge specific capacity of the FeF 3 -CNTs positive electrode composite of Example 1 is reduced from 600 mAhg -1 of initial capacity to 300 mAhg -1 , and the capacity retention rate is 50%.
  • FeF 3 and the positive electrode material of Comparative Example 1 under the same test conditions, after 10 charge-discharge cycles, the discharge capacity of the battery is decreased from the initial capacity 350mAhg -1 100 mAhg -1, the capacity retention rate was 28.5 %. It is indicated that the FeF 3 -CNTs positive electrode composite has higher capacity and capacity retention than the FeF 3 positive electrode material.
  • the battery composed of the FeF 3 -CNTs positive electrode composite material of Example 1 and the FeF 3 positive electrode material of Comparative Example 1 was in the range of 2.0 V to 4.5 V, respectively, at 50 mAg -1 , 100 mAg -1 and 500 mAg -1 .
  • Charge and discharge tests were performed at current density. Referring to FIG. 8-9, it can be seen that the discharge capacity of the FeF 3 -CNTs positive electrode composite of Example 1 at a current density of 50 mAg -1 , 100 mAg -1 , and 500 mAg -1 is 175 mAhg -1 , respectively. , 170 mAhg -1, 100 mAg -1 .
  • the discharge capacities of the iron fluoride cathode materials of Comparative Example 1 at 50 mAg -1 , 100 mAg -1 , and 500 mAg -1 were 110 mAhg -1 , 100 mAhg -1 , and 70 mAhg -1 , respectively .
  • FeF 3 -CNTs cathode composites have higher discharge capacity than ferric fluoride materials.
  • the FeF 3 -CNTs cathode composite has a higher discharge capacity and a smaller battery capacity attenuation ratio.
  • the battery composed of the FeF 3 -CNTs positive electrode composite material of Example 2 was subjected to a constant current cycle charge and discharge test at a current density of 50 mAg -1 and a voltage range of 2.0 V to 4.5 V. After the first discharge, the discharge capacity of the battery was 173.9 mAhg -1 , and the battery capacity decay was less than 5% after 20 cycles.
  • the battery composed of the FeF 3 -CNTs positive electrode composite material of Example 3 was subjected to a constant current cycle charge and discharge test at a current density of 100 mAg -1 and a voltage range of 2.0 V to 4.5 V. After the first discharge, the battery has a discharge capacity of 170 mAhg -1 , and the battery capacity decays less than 5% after 20 cycles. It is indicated that the FeF 3 -CNTs positive electrode composite has high discharge capacity and good cycle capacity.
  • a FeF 3 -CNTs positive electrode composite material is obtained by combining carbon nanotubes with iron fluoride.
  • the carbon nanotubes and the ferric fluoride particles form a three-dimensional conductive network, and an electron transport channel is provided during charging and discharging of the battery, so that the FeF 3 -CNTs positive electrode composite material has high conductivity. Therefore, the battery composed of FeF 3 -CNTs positive electrode composite material has higher discharge capacity and better cycle capacity, and has a more obvious charging and discharging platform.
  • the invention adopts the method of coprecipitation to prepare the FeF 3 -CNTs positive electrode composite material, and does not damage the ferric fluoride structure, so that the FeF 3 -CNTs positive electrode composite material can effectively utilize the high energy density of the ferric fluoride and the excellent high temperature heat stability.
  • sexual advantage Moreover, no surfactant is used in the preparation process, and the preparation process is simple.

Abstract

A lithium ion battery anode composite material and a preparing method thereof. The anode composite material comprises a plurality of ferric fluoride particles and a plurality of carbon nanotubes. The plurality of ferric fluoride particles and the plurality of carbon nanotubes form a three-dimensional conductive network. The plurality of carbon nanotubes is uniformly dispersed among the plurality of ferric fluoride particles and at least parts of the ferric fluoride particles are connected by using the carbon nanotubes. The preparing method comprises the following steps: providing a carbon nanotube raw material and an HF solution; dispersing the carbon nanotube raw material in the HF solution to form a first suspension liquid; providing an FeCl3 solution, and mixing the FeCl3 solution with the first suspension liquid, to obtain a precipitate FeF3∙3H2O-CNTs; and separating and purifying the precipitate, and performing heat treatment on the precipitate, so as to obtain the lithium ion battery anode composite material.

Description

锂离子电池正极复合材料及其制备方法Lithium ion battery positive electrode composite material and preparation method thereof 技术领域Technical field
本发明涉及一种锂离子电池正极复合材料及其制备方法，尤其涉及一种包含氟化铁的锂离子电池正极复合材料及其制备方法。The invention relates to a lithium ion battery cathode composite material and a preparation method thereof, in particular to a lithium ion battery cathode composite material comprising ferric fluoride and a preparation method thereof.
背景技术Background technique
目前，随着锂离子电池应用领域的不断拓展，如新型能源存储与电力汽车领域，市场对高功率、高能量密度电池的需求越来越大。氟化铁（FeF3）因其具有很高的理论能量密度及优异的高温热稳定性，而受到广泛关注。At present, with the continuous expansion of lithium ion battery applications, such as new energy storage and electric vehicles, the market is increasingly demanding high-power, high-energy density batteries. Ferric fluoride (FeF 3 ) has received extensive attention due to its high theoretical energy density and excellent high temperature thermal stability.
然而，由于FeF3的电导率较低，且充放电过程中转化反应产物LiF的非导电性使得转化反应的动力学过程非常迟缓。以上因素限制了FeF3在锂离子电池中的实际应用。However, since the conductivity of FeF 3 is low, and the non-conductivity of the conversion reaction product LiF during charge and discharge makes the kinetics of the conversion reaction very slow. The above factors limit the practical application of FeF 3 in lithium ion batteries.
目前，主要采用减小氟化铁的颗粒尺寸和使用第二相导电材料作为其担载载体相结合的方式，来改善氟化铁的导电性、提高电极动力学反应速率。颗粒尺寸减小可以减小电子传输路径、增大反应面积，从而提高氟化铁的电化学活性。使用第二相导电材料作为其担载载体即是将氟化铁颗粒与另外一种电导率较好的材料相结合来提高其电化学性能。目前已报道的第二相材料有：中孔炭、活性炭球、PEDOT、V2O5、MoS2、石墨烯或碳纳米管。在上述各种第二相材料中，碳纳米管具有独特的一维纳米结构、优异的电子传导性和热传导性及低密度，被认为是改善电极材料导电性的理想材料。目前韩国研究人员制备出花状氟化铁颗粒与碳纳米管复合的结构，其制备过程中使用了表面活性剂CTAB。其中，表面活性剂较难去除，导致最终产物中易存在残余的CTAB，而CTAB会对电池电极材料的电化学性能产生不利影响。At present, the combination of the particle size of the iron fluoride and the use of the second phase conductive material as the carrier of the carrier is mainly used to improve the conductivity of the iron fluoride and increase the reaction rate of the electrode kinetics. The particle size reduction can reduce the electron transport path and increase the reaction area, thereby increasing the electrochemical activity of the ferric fluoride. The use of a second phase conductive material as its supporting carrier combines iron fluoride particles with another material having a better electrical conductivity to improve its electrochemical performance. The second phase materials that have been reported so far are: mesoporous carbon, activated carbon spheres, PEDOT, V 2 O 5 , MoS 2 , graphene or carbon nanotubes. Among the various second phase materials described above, carbon nanotubes have unique one-dimensional nanostructures, excellent electron conductivity and thermal conductivity, and low density, and are considered to be ideal materials for improving the conductivity of electrode materials. At present, Korean researchers have prepared a structure in which flower-like ferric fluoride particles are combined with carbon nanotubes, and a surfactant CTAB is used in the preparation process. Among them, the surfactant is difficult to remove, resulting in the residual CTAB in the final product, and CTAB will adversely affect the electrochemical performance of the battery electrode material.
发明内容Summary of the invention
有鉴于此，确有必要提供一种制备过程中未使用任何表面活性剂的锂离子电池正极复合材料的制备方法，以及使用该方法制备的氟化铁（FeF3）-碳纳米管（CNT）正极复合材料。Needed, therefore, it is necessary to provide a lithium ion battery cathode composite material prepared without using any surfactant the process for preparing, as well as iron fluoride (FeF 3) was prepared using the method - a carbon nanotube (CNT) Positive electrode composite.
一种锂离子电池正极复合材料，包括多个氟化铁颗粒及多个碳纳米管，所述多个氟化铁颗粒及多个碳纳米管形成一三维导电网络，其中，所述多个碳纳米管分散于所述多个氟化铁颗粒之间，至少部分所述氟化铁颗粒通过所述碳纳米管连接。A lithium ion battery cathode composite material comprising a plurality of ferric fluoride particles and a plurality of carbon nanotubes, wherein the plurality of ferric fluoride particles and the plurality of carbon nanotubes form a three-dimensional conductive network, wherein the plurality of carbons The nanotubes are dispersed between the plurality of ferric fluoride particles, and at least a portion of the iron fluoride particles are connected by the carbon nanotubes.
一种锂离子电池正极复合材料的制备方法，包括如下步骤：提供一碳纳米管原料、以及一HF溶液；将所述碳纳米管原料分散于所述HF溶液中，形成一第一悬浊液；提供一FeCl3溶液，并将所述FeCl3溶液与所述第一悬浊液混合，得到一沉淀物FeF3∙3H2O-CNTs；以及将所述沉淀物分离提纯，并热处理所述沉淀物，从而获得所述锂离子电池正极复合材料。A method for preparing a positive electrode composite material for a lithium ion battery, comprising the steps of: providing a carbon nanotube raw material, and an HF solution; dispersing the carbon nanotube raw material in the HF solution to form a first suspension Providing a FeCl 3 solution, and mixing the FeCl 3 solution with the first suspension to obtain a precipitate FeF 3 ∙3H 2 O-CNTs; and separating and purifying the precipitate, and heat treating the A precipitate is obtained to obtain the lithium ion battery positive electrode composite.
相较于现有技术，所述通过将碳纳米管与氟化铁进行复合，采用共沉淀的方法，且反应过程中未使用任何表面活性剂，制备获得FeF3- CNTs正极复合材料。使得碳纳米管与氟化铁颗粒形成一三维导电网络，在电池充放电过程中会提供电子传输通道，使得FeF3-CNTs正极复合材料具有较高的导电率。故，由FeF3-CNTs正极复合材料组成的电池具有较高的放电容量及较好的循环能力，且具有较明显的充放电平台。Compared with the prior art, the FeF 3 -CNTs positive electrode composite material is prepared by combining carbon nanotubes with iron fluoride, adopting a coprecipitation method, and using no surfactant during the reaction. The carbon nanotubes and the ferric fluoride particles form a three-dimensional conductive network, and an electron transport channel is provided during charging and discharging of the battery, so that the FeF 3 -CNTs positive electrode composite material has high conductivity. Therefore, the battery composed of FeF 3 -CNTs positive electrode composite material has higher discharge capacity and better cycle capacity, and has a more obvious charging and discharging platform.
附图说明DRAWINGS
图1是本发明实施例提供的锂离子电池正极复合材料制备方法流程图。1 is a flow chart of a method for preparing a positive electrode composite material for a lithium ion battery according to an embodiment of the present invention.
图2是本发明实施例1的FeF3-CNTs正极复合材料的扫描电镜照片。2 is a scanning electron micrograph of a FeF 3 -CNTs positive electrode composite material of Example 1 of the present invention.
图3是本发明实施例1中间产物FeF3∙3H2O-CNTs的XRD衍射图谱。Figure 3 is an XRD diffraction pattern of the intermediate product FeF 3 ∙3H 2 O-CNTs of Example 1 of the present invention.
图4是本发明实施例1的FeF3-CNTs正极复合材料的XRD衍射图谱。4 is an XRD diffraction pattern of a FeF 3 -CNTs positive electrode composite material of Example 1 of the present invention.
图5是本发明实施例1的FeF3-CNTs正极复合材料在1.0V-4.5V电压下的首次充放电测试曲线。Fig. 5 is a graph showing the first charge and discharge test of the FeF 3 -CNTs positive electrode composite material of Example 1 of the present invention at a voltage of 1.0 V to 4.5 V.
图6是本发明对比例1的FeF3正极材料在1.0V-4.5V电压下的首次充放电测试曲线。Fig. 6 is a graph showing the first charge and discharge test of the FeF 3 positive electrode material of Comparative Example 1 at a voltage of 1.0 V to 4.5 V.
图7是本发明实施例1的FeF3-CNTs正极复合材料的恒流充放电测试曲线。Fig. 7 is a graph showing a constant current charge and discharge test of the FeF 3 -CNTs positive electrode composite material of Example 1 of the present invention.
图8是本发明实施例1的FeF3-CNTs正极复合材料在不同电力密度下的倍率放电曲线。Fig. 8 is a graph showing the rate discharge curve of the FeF 3 -CNTs positive electrode composite material of Example 1 of the present invention at different power densities.
图9是本发明对比例1的FeF3正极材料在不同电流密度下的倍率放电曲线。Figure 9 is a graph showing the rate discharge curve of the FeF 3 cathode material of Comparative Example 1 at different current densities.
图10是本发明对比例1的FeF3正极材料与实施例1的FeF3-CNTs正极复合材料的充放电循环测试比较图。Fig. 10 is a graph showing a comparison of charge and discharge cycle tests of the FeF 3 positive electrode material of Comparative Example 1 and the FeF 3 -CNTs positive electrode composite material of Example 1.
具体实施方式detailed description
以下将结合附图详细说明本发明锂离子电池正极复合材料及其制备方法。Hereinafter, a lithium ion battery positive electrode composite material of the present invention and a preparation method thereof will be described in detail with reference to the accompanying drawings.
请参阅图1，本发明实施例提供一种锂离子电池正极复合材料的制备方法，其包括以下步骤：Referring to FIG. 1 , an embodiment of the present invention provides a method for preparing a positive electrode composite material for a lithium ion battery, which includes the following steps:
S1:提供一碳纳米管原料以及一HF溶液；S1: providing a carbon nanotube raw material and an HF solution;
S2:将所述碳纳米管原料分散于所述HF溶液中，形成一第一悬浊液；S2: dispersing the carbon nanotube raw material in the HF solution to form a first suspension;
S3:提供一FeCl3溶液，并将所述FeCl3溶液与所述第一悬浊液混合，得到一沉淀物FeF3∙3H2O-CNTs；以及S3: providing a FeCl 3 solution, and mixing the FeCl 3 solution with the first suspension to obtain a precipitate FeF 3 ∙3H 2 O-CNTs;
S4:将所述沉淀物分离提纯，并热处理所述沉淀物，从而获得所述锂离子电池正极复合材料。S4: separating and precipitating the precipitate, and heat treating the precipitate to obtain the lithium ion battery positive electrode composite.
在步骤S1中，所述碳纳米管原料可为单壁碳纳米管、双壁碳纳米管或多壁碳纳米管中的一种或几种。该碳纳米管的内径优选为2纳米~15纳米，外径为10纳米~30纳米，长度为几百微米左右。该碳纳米管原料可通过电弧放电法、化学气相沉积法或激光蒸发法等方法制备。所述HF溶液为将HF气体溶解于水中制备而成，该HF溶液中HF的质量分数为30%-40%。In step S1, the carbon nanotube raw material may be one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, or multi-walled carbon nanotubes. The carbon nanotubes preferably have an inner diameter of 2 nm to 15 nm, an outer diameter of 10 nm to 30 nm, and a length of several hundred micrometers. The carbon nanotube raw material can be prepared by an arc discharge method, a chemical vapor deposition method, or a laser evaporation method. The HF solution is prepared by dissolving HF gas in water, and the mass fraction of HF in the HF solution is 30% to 40%.
在步骤S2中，所述碳纳米管原料可以通过机械搅拌或超声搅拌的方式分散于所述HF溶液中。所述碳纳米管原料在所述HF溶液中均匀分布，从而形成所述第一悬浊液。In step S2, the carbon nanotube raw material may be dispersed in the HF solution by mechanical stirring or ultrasonic stirring. The carbon nanotube material is uniformly distributed in the HF solution to form the first suspension.
在步骤S3中，所述FeCl3溶液可以通过将FeCl3∙6H2O颗粒溶解于一溶剂中制备而成，或通过其他方式获得。所述溶剂可以为去离子水、甲醇、乙醇、丙酮、***中的一种或几种。所述FeCl3溶液的浓度不限，可以根据溶剂的选择及实际需要配置。由于在反应过程中氟会发生少量损耗，故，加入过量的HF可以用来补偿反应过程中氟的损耗。具体地，所述第一悬浊液与所述FeCl3溶液按照HF与FeCl3的摩尔浓度比大于3：1，所述碳纳米管原料与所述FeCl3溶液中FeCl3的质量比为0.007：1～0.08：1混合。优选地，所述第一悬浊液与所述FeCl3溶液按照HF与FeCl3的摩尔浓度比为3.1：1～3.2：1混合。从而使所述碳纳米管在最终制备的锂离子电池正极复合材料中的质量百分比为1-10%。In step S3, the FeCl 3 solution may be prepared by dissolving FeCl 3 ∙6H 2 O particles in a solvent, or by other means. The solvent may be one or more of deionized water, methanol, ethanol, acetone, and diethyl ether. The concentration of the FeCl 3 solution is not limited, and may be configured according to the selection of the solvent and actual needs. Since a small amount of fluorine is lost during the reaction, excessive HF can be added to compensate for the loss of fluorine during the reaction. In particular, the suspension of the first molar solution of FeCl 3 and FeCl 3 HF concentration is greater than 3: 1, mass ratio of the carbon nanotube feedstock solution with the FeCl 3 FeCl 3 0.007 : 1 to 0.08:1 mixed. Preferably, the first suspension and the FeCl 3 solution are mixed according to a molar concentration ratio of HF to FeCl 3 of 3.1:1 to 3.2:1. Thereby, the mass percentage of the carbon nanotubes in the finally prepared lithium ion battery positive electrode composite is 1-10%.
所述FeCl3溶液可以通过滴加的方式逐滴滴入所述第一悬浊液中进行反应，具体地，滴加速度优选5秒每滴。从而使整个反应过程中氟处于过量的状态，从而得到纯相的FeF3。所述FeCl3溶液也可以与所述第一悬浊液同时滴入另一反应器中进行反应。反应过程中，所述FeCl3溶液中的Fe3+与所述第一悬浊液中的F—反应生成水合物FeF3·3H2O沉淀。与此同时，所述碳纳米管原料会缠绕在所述FeF3·3H2O颗粒上，或分散在FeF3·3H2O颗粒之间，从而形成多个导电通道。另外，在反应过程中，可以通过机械搅拌、超声搅拌或磁力搅拌的方式使所述第一悬浊液、FeCl3溶液充分反应。进一步地，反应完毕后，可以继续搅拌混合液10-12小时，使所述沉淀物与所述碳纳米管原料均匀分散。The FeCl 3 solution may be dropwise added to the first suspension by dropwise addition to carry out the reaction, and specifically, the dropping acceleration is preferably 5 seconds per drop. Thereby, the fluorine is in an excessive state throughout the reaction, thereby obtaining pure phase FeF 3 . The FeCl 3 solution may also be dropped into another reactor simultaneously with the first suspension to carry out a reaction. During the reaction, Fe 3+ in the FeCl 3 solution and the suspension of the first F - Reaction hydrate FeF 3 · 3H 2 O precipitates. At the same time, the carbon nanotube raw material may be entangled on the FeF 3 .3H 2 O particles or dispersed between the FeF 3 .3H 2 O particles to form a plurality of conductive channels. In addition, during the reaction, the first suspension and the FeCl 3 solution may be sufficiently reacted by mechanical stirring, ultrasonic stirring or magnetic stirring. Further, after the reaction is completed, the mixture may be continuously stirred for 10 to 12 hours to uniformly disperse the precipitate and the carbon nanotube raw material.
在步骤S4中，所述沉淀物可以通过过滤的方法与液相分离，从而获得所述沉淀物。所述过滤方法可以是常压过滤或真空抽滤。所述常压过滤的方法具体包括，将所述混合溶液倒入一放有滤纸的漏斗中，静置一段时间从而获得所述沉淀物。所述真空抽滤的方法具体包括提供一微孔滤膜及一抽气漏斗，将所述混合溶液经过该微孔滤膜倒入该抽气漏斗中，抽滤并获得一所述沉淀物。另外，可以进一步包括用去离子水洗涤该沉淀物的步骤以及将所述沉淀物进行干燥的步骤。所述干燥步骤优选将所述沉淀物转入鼓风干燥箱中，并在60℃左右条件下烘干8-10小时。In step S4, the precipitate may be separated from the liquid phase by a filtration method to obtain the precipitate. The filtration method may be atmospheric filtration or vacuum filtration. The method of atmospheric filtration specifically includes pouring the mixed solution into a funnel in which filter paper is placed, and allowing to stand for a period of time to obtain the precipitate. The vacuum filtration method specifically includes providing a microporous membrane and an evacuation funnel, pouring the mixed solution into the suction funnel through the microfiltration membrane, suctioning and obtaining a precipitate. Additionally, a step of washing the precipitate with deionized water and a step of drying the precipitate may be further included. The drying step preferably transfers the precipitate to a blast drying oven and is dried for 8-10 hours at about 60 °C.
所述热处理FeF3∙3H2O-CNTs在N2、Ar等惰性气氛中进行，热处理的温度为120℃-170℃，从而有利于避免正极复合材料中杂相的产生，得到纯相的FeF3-CNTs正极复合材料。优选地，该热处理温度约为125℃-140℃。具体地，烧结的温度曲线可以设定为：由室温升温至120℃-170℃；升温速率可以为3～5℃/min；保温时间设定为8～12个小时。The heat-treated FeF 3 ∙3H 2 O-CNTs are carried out in an inert atmosphere such as N 2 or Ar, and the heat treatment temperature is 120 ° C - 170 ° C, thereby facilitating the generation of the hetero phase in the positive electrode composite material, and obtaining the pure phase FeF. 3 -CNTs positive electrode composite. Preferably, the heat treatment temperature is about 125 ° C to 140 ° C. Specifically, the temperature profile of the sintering may be set to: from room temperature to 120 ° C to 170 ° C; the heating rate may be 3 to 5 ° C / min; the holding time is set to 8 to 12 hours.
实施例1：Example 1:
将200 mg碳纳米管加入80 mL HF（38%质量百分比）水溶液中，超声分散2h得到第一悬浊液；将27.027 g FeCl3.6H2O溶于20mL去离子水中得到FeCl3溶液；在磁力搅拌条件下，将所述FeCl3溶液逐滴滴入所述第一悬浊液中，继续磁力搅拌10h，得到一含沉淀物的混合液；过滤所述混合液，将所述沉淀物在60℃干燥10h，将所述沉淀物在125℃的Ar气氛中热处理10h，得到FeF3-CNTs正极复合材料。200 mg of carbon nanotubes were added to 80 mL of HF (38% by mass) aqueous solution, and ultrasonically dispersed for 2 hours to obtain a first suspension; 27.027 g of FeCl 3 .6H 2 O was dissolved in 20 mL of deionized water to obtain a FeCl 3 solution; Under magnetic stirring, the FeCl 3 solution was dropped into the first suspension dropwise, and magnetic stirring was continued for 10 h to obtain a mixture containing a precipitate; the mixture was filtered, and the precipitate was placed at After drying at 60 ° C for 10 h, the precipitate was heat-treated in an Ar atmosphere at 125 ° C for 10 h to obtain a FeF 3 -CNTs positive electrode composite.
实施例2：Example 2:
将300 mg碳纳米管加入40 mL HF（38%质量百分比）水溶液中，超声分散1h得到第一悬浊液；将40.54 g FeCl3.6H2O溶于40 mL 去离子水中得到FeCl3溶液；在磁力搅拌条件下，将所述FeCl3溶液逐滴滴入所述第一悬浊液中，继续磁力搅拌10 h，得到一含沉淀物的混合液；过滤所述混合液，将所述沉淀物在60℃干燥10h，将所述沉淀物在130℃的N2气氛中热处理10h，得到FeF3-CNTs正极复合材料。The 300 mg of carbon nanotubes 40 mL HF (38% by mass percentage) of an aqueous solution, an ultrasonic dispersion to obtain a first suspension 1h; and 40.54 g FeCl 3 .6H 2 O dissolved in 40 mL of deionized water to obtain a solution of FeCl 3; Under magnetic stirring, the FeCl 3 solution was dropped into the first suspension dropwise, and magnetic stirring was continued for 10 h to obtain a mixture containing a precipitate; the mixture was filtered to precipitate the precipitate. The material was dried at 60 ° C for 10 h, and the precipitate was heat-treated in an N 2 atmosphere at 130 ° C for 10 h to obtain a FeF 3 -CNTs positive electrode composite.
实施例3：Example 3:
将500 mg碳纳米管加入100 mL HF（38%质量百分比）水溶液中，超声分散3h得到第一悬浊液；将54.058 g FeCl3.6H2O溶于100 mL 去离子水中得到FeCl3溶液；在磁力搅拌条件下，将所述FeCl3溶液逐滴滴入所述第一悬浊液中，继续磁力搅拌10 h，得到一含沉淀物的混合液；过滤所述混合液，将所述沉淀物在60℃干燥10h，将所述沉淀物在140℃的N2气氛中热处理10h，得到FeF3-CNTs正极复合材料。The 500 mg of carbon nanotubes 100 mL HF (38% by mass percentage) of an aqueous solution, an ultrasonic dispersing 3h to give a first suspension; and 54.058 g FeCl 3 .6H 2 O was dissolved in 100 mL of deionized water to obtain a solution of FeCl 3; Under magnetic stirring, the FeCl 3 solution was dropped into the first suspension dropwise, and magnetic stirring was continued for 10 h to obtain a mixture containing a precipitate; the mixture was filtered to precipitate the precipitate. The material was dried at 60 ° C for 10 h, and the precipitate was heat-treated in a N 2 atmosphere at 140 ° C for 10 h to obtain a FeF 3 -CNTs positive electrode composite.
对比例1：Comparative example 1:
对比例1与实施例1基本相同，其区别仅在于不添加碳纳米管。Comparative Example 1 was substantially the same as Example 1, except that no carbon nanotubes were added.
请参阅图2，所述FeF3-CNTs正极复合材料包括多个氟化铁颗粒以及多个碳纳米管，所述碳纳米管均匀分散于所述氟化铁颗粒之间或缠绕于所述氟化铁颗粒上形成一三维导电网络，多个氟化铁颗粒通过多个碳纳米管连接，多个碳纳米管形成多个导电通道。所述氟化铁颗粒为棒状，其长度为2微米到6微米，直径为100纳米到300纳米，且每个棒状氟化铁由多个直径为30nm左右的纳米氟化铁颗粒组成。Referring to FIG. 2, the FeF 3 -CNTs positive electrode composite material includes a plurality of iron fluoride particles and a plurality of carbon nanotubes uniformly dispersed between the iron fluoride particles or entangled in the fluorination A three-dimensional conductive network is formed on the iron particles, and the plurality of iron fluoride particles are connected by a plurality of carbon nanotubes, and the plurality of carbon nanotubes form a plurality of conductive channels. The iron fluoride particles are rod-shaped, have a length of 2 micrometers to 6 micrometers, and have a diameter of 100 nanometers to 300 nanometers, and each of the rod-shaped iron fluorides is composed of a plurality of nano-fluorinated iron particles having a diameter of about 30 nm.
请一并参阅图3-4，从图中可以看出，实施例1得到的FeF3-CNTs正极复合材料的衍射峰位置与PDF标准图谱完全对应，且各衍射峰强度较高，峰形较尖锐，说明得到的FeF3-CNTs正极复合材料是纯相，无其他杂相存在。Referring to FIG. 3-4 together, it can be seen from the figure that the diffraction peak position of the FeF 3 -CNTs positive electrode composite obtained in Example 1 completely corresponds to the PDF standard map, and the intensity of each diffraction peak is higher, and the peak shape is higher. Sharp, indicating that the obtained FeF 3 -CNTs positive electrode composite is pure phase, no other impurity phase exists.
将实施例1、实施例2、实施例3得到的FeF3-CNTs正极复合材料，及对比例1得到的FeF3正极材料，分别作为正极材料组成电池进行电池性能测试。The FeF 3 -CNTs positive electrode composite materials obtained in Example 1, Example 2, and Example 3, and the FeF 3 positive electrode material obtained in Comparative Example 1 were respectively used as positive electrode materials to constitute a battery for battery performance test.
该测试电池的正极包括以下组分：The positive electrode of the test cell includes the following components:
材料material 组分Component 质量百分比Mass percentage
正极材料Cathode material 实施例1样品或实施例2样品或实施例3样品或对比例1样品Example 1 sample or Example 2 sample or Example 3 sample or Comparative Example 1 sample 80%80%
导电剂 Conductive agent 石墨graphite 10%10%
粘结剂Binder 聚偏二氟乙烯(PVDF)溶于N-甲基吡咯烷酮(NMP)溶剂Polyvinylidene fluoride (PVDF) is dissolved in N-methylpyrrolidone (NMP) solvent 10%10%
将所述各组分充分搅拌混合形成一浆料，并涂覆于铝箔集流体表面，然后在120℃真空干燥24小时。以金属锂片为负极，Celgard 2400微孔聚丙烯膜为隔膜，以1mol/L LiPF6/EC+DMC+DEC（1：1：1体积比）为电解液，在氩气气氛手套箱中组成纽扣电池。The components were thoroughly stirred and mixed to form a slurry, which was applied to the surface of the aluminum foil current collector, and then vacuum dried at 120 ° C for 24 hours. The lithium metal plate was used as the negative electrode, and the Celgard 2400 microporous polypropylene film was used as the separator. The composition was composed of 1 mol/L LiPF 6 /EC+DMC+DEC (1:1:1 volume ratio) as an electrolyte in an argon atmosphere glove box. Button Battery.
将实施例1的FeF3-CNTs正极复合材料及对比例1的FeF3正极材料组成的电池分别在100 mAg-1的电流密度下，及1.0V～4.5V范围内进行充放电测试及恒流充放电测试。请参阅图5-6，可以看出，实施例1的FeF3-CNTs正极复合材料具有较明显三电子充放电平台，且具有较高的放电容量，首次放电容量可以达到600 mAhg-1左右；而对比例1的FeF3正极材料的三电子充放电平台不明显，且其首次放电容量仅达到350 mAhg-1左右。The battery composed of the FeF 3 -CNTs positive electrode composite material of Example 1 and the FeF 3 positive electrode material of Comparative Example 1 was subjected to charge and discharge test and constant current at a current density of 100 mAg -1 and a range of 1.0 V to 4.5 V, respectively. Charge and discharge test. Referring to FIG. 5-6, it can be seen that the FeF 3 -CNTs positive electrode composite material of the embodiment 1 has a relatively obvious three-electron charging and discharging platform and has a high discharge capacity, and the first discharge capacity can reach about 600 mAhg -1 ; The three-electron charging and discharging platform of the FeF 3 positive electrode material of Comparative Example 1 is not obvious, and its initial discharge capacity is only about 350 mAhg -1 .
请一并参阅图7，在经过10次充放电循环后，实施例1的FeF3-CNTs正极复合材料的放电比容量由初始容量的600 mAhg-1降至300 mAhg-1，容量保持率为50%。而对比例1的FeF3正极材料，在相同的测试条件下，经过10次充放电循环后，电池的放电比容量由初始容量的350mAhg-1降至100 mAhg-1，容量保持率仅为28.5%。说明FeF3-CNTs正极复合材料比FeF3正极材料具有较高的容量及容量保持率。Referring to FIG. 7 together, after 10 cycles of charge and discharge, the discharge specific capacity of the FeF 3 -CNTs positive electrode composite of Example 1 is reduced from 600 mAhg -1 of initial capacity to 300 mAhg -1 , and the capacity retention rate is 50%. FeF 3 and the positive electrode material of Comparative Example 1, under the same test conditions, after 10 charge-discharge cycles, the discharge capacity of the battery is decreased from the initial capacity 350mAhg -1 100 mAhg -1, the capacity retention rate was 28.5 %. It is indicated that the FeF 3 -CNTs positive electrode composite has higher capacity and capacity retention than the FeF 3 positive electrode material.
将实施例1的FeF3-CNTs正极复合材料及对比例1的FeF3正极材料组成的电池在2.0V～4.5V范围内，分别在50 mAg-1、 100 mAg-1 及500 mAg-1的电流密度下进行充放电测试。请参阅图8-9，可以看出，实施例1的FeF3-CNTs正极复合材料在50 mAg-1、100 mAg-1 、500 mAg-1电流密度下的的放电容量分别是175 mAhg-1 、 170 mAhg-1 、100 mAg-1。而对比例1的氟化铁正极材料在50mAg-1、100 mAg-1、500 mAg-1电流下的的放电容量分别是110 mAhg-1、 100 mAhg-1、 70 mAhg-1，说明在2.0V～4.5V范围内，及在50 mAg-1、 100 mAg-1 及500 mAg-1的电流密度下，FeF3-CNTs正极复合材料比氟化铁材料具有更高的放电容量。The battery composed of the FeF 3 -CNTs positive electrode composite material of Example 1 and the FeF 3 positive electrode material of Comparative Example 1 was in the range of 2.0 V to 4.5 V, respectively, at 50 mAg -1 , 100 mAg -1 and 500 mAg -1 . Charge and discharge tests were performed at current density. Referring to FIG. 8-9, it can be seen that the discharge capacity of the FeF 3 -CNTs positive electrode composite of Example 1 at a current density of 50 mAg -1 , 100 mAg -1 , and 500 mAg -1 is 175 mAhg -1 , respectively. , 170 mAhg -1, 100 mAg -1 . The discharge capacities of the iron fluoride cathode materials of Comparative Example 1 at 50 mAg -1 , 100 mAg -1 , and 500 mAg -1 were 110 mAhg -1 , 100 mAhg -1 , and 70 mAhg -1 , respectively . In the range of V~4.5V, and at current densities of 50 mAg -1 , 100 mAg -1 and 500 mAg -1 , FeF 3 -CNTs cathode composites have higher discharge capacity than ferric fluoride materials.
请一并参阅图10，可以看出，在2.0V～4.5V的电压范围内，在50mAg-1、100mAg-1 、及 500mAg-1电流下分别循环充放电5次后。与FeF3正极材料相比，FeF3-CNTs正极复合材料的放电容量较高，且电池容量衰减比例较小。Referring to FIG. 10 together, it can be seen that after charging and discharging five times in the voltage range of 2.0V to 4.5V at 50mAg -1 , 100mAg -1 , and 500mAg -1 respectively. Compared with the FeF 3 cathode material, the FeF 3 -CNTs cathode composite has a higher discharge capacity and a smaller battery capacity attenuation ratio.
实施例2中的FeF3-CNTs正极复合材料组成的电池在50 mAg-1的电流密度下，及2.0V～4.5V的电压范围内，进行恒流循环充放电测试。首次放电后，电池的放电容量为173.9mAhg-1，20次循环后电池容量衰减低于5%。实施例3中的FeF3-CNTs正极复合材料组成的电池在100 mAg-1的电流密度下，及2.0V～4.5V的电压范围内，进行恒流循环充放电测试。首次放电后，电池的放电容量为170mAhg-1，20次循环后电池容量衰减低于5%。说明该FeF3-CNTs正极复合材料具有较高的放电容量及较好的循环能力。The battery composed of the FeF 3 -CNTs positive electrode composite material of Example 2 was subjected to a constant current cycle charge and discharge test at a current density of 50 mAg -1 and a voltage range of 2.0 V to 4.5 V. After the first discharge, the discharge capacity of the battery was 173.9 mAhg -1 , and the battery capacity decay was less than 5% after 20 cycles. The battery composed of the FeF 3 -CNTs positive electrode composite material of Example 3 was subjected to a constant current cycle charge and discharge test at a current density of 100 mAg -1 and a voltage range of 2.0 V to 4.5 V. After the first discharge, the battery has a discharge capacity of 170 mAhg -1 , and the battery capacity decays less than 5% after 20 cycles. It is indicated that the FeF 3 -CNTs positive electrode composite has high discharge capacity and good cycle capacity.
由于碳纳米管具有独特的一维纳米结构、优异的电子传导性、高比表面积、及低密度等特性，是改善电极材料导电性的理想材料。本发明通过将碳纳米管与氟化铁进行复合，获得FeF3- CNTs正极复合材料。使得碳纳米管与氟化铁颗粒形成一三维导电网络，在电池充放电过程中会提供电子传输通道，使得FeF3-CNTs正极复合材料具有较高的导电率。故，由FeF3-CNTs正极复合材料组成的电池具有较高的放电容量及较好的循环能力，且具有较明显的充放电平台。另外，本发明采用共沉淀的方法制备FeF3- CNTs正极复合材料，不会破坏氟化铁结构，使得FeF3- CNTs正极复合材料能够有效利用氟化铁的高能量密度及优异的高温热稳定性的优势。且制备过程中未使用任何表面活性剂，制备过程简单。Due to its unique one-dimensional nanostructure, excellent electron conductivity, high specific surface area, and low density, carbon nanotubes are ideal materials for improving the conductivity of electrode materials. In the present invention, a FeF 3 -CNTs positive electrode composite material is obtained by combining carbon nanotubes with iron fluoride. The carbon nanotubes and the ferric fluoride particles form a three-dimensional conductive network, and an electron transport channel is provided during charging and discharging of the battery, so that the FeF 3 -CNTs positive electrode composite material has high conductivity. Therefore, the battery composed of FeF 3 -CNTs positive electrode composite material has higher discharge capacity and better cycle capacity, and has a more obvious charging and discharging platform. In addition, the invention adopts the method of coprecipitation to prepare the FeF 3 -CNTs positive electrode composite material, and does not damage the ferric fluoride structure, so that the FeF 3 -CNTs positive electrode composite material can effectively utilize the high energy density of the ferric fluoride and the excellent high temperature heat stability. Sexual advantage. Moreover, no surfactant is used in the preparation process, and the preparation process is simple.
另外，本领域技术人员还可在本发明精神内作其它变化，当然这些依据本发明精神所作的变化，都应包含在本发明所要求保护的范围内。In addition, those skilled in the art can make other changes within the spirit of the invention, and it is to be understood that these changes are intended to be included within the scope of the invention.

Claims (10)

  1. 一种锂离子电池正极复合材料，其特征在于，包括多个氟化铁颗粒及多个碳纳米管，所述多个氟化铁颗粒及多个碳纳米管形成一三维导电网络，其中，所述多个碳纳米管分散于所述多个氟化铁颗粒之间，至少部分所述氟化铁颗粒通过所述碳纳米管连接。 A positive electrode composite material for a lithium ion battery, comprising: a plurality of ferric fluoride particles and a plurality of carbon nanotubes, wherein the plurality of ferric fluoride particles and the plurality of carbon nanotubes form a three-dimensional conductive network, wherein The plurality of carbon nanotubes are dispersed between the plurality of iron fluoride particles, and at least a portion of the iron fluoride particles are connected by the carbon nanotubes.
  2. 如权利要求1所述的锂离子电池正极复合材料，其特征在于，所述多个碳纳米管缠绕在所述氟化铁颗粒上。 The lithium ion battery positive electrode composite according to claim 1, wherein the plurality of carbon nanotubes are wound on the iron fluoride particles.
  3. 如权利要求1所述的锂离子电池正极复合材料，其特征在于，所述氟化铁颗粒为棒状，其长度为2微米到6微米，直径为100纳米到300纳米，且每个棒状氟化铁由多个直径为30 nm的纳米氟化铁颗粒组成。 The lithium ion battery positive electrode composite according to claim 1, wherein the iron fluoride particles are rod-shaped, having a length of 2 to 6 μm, a diameter of 100 nm to 300 nm, and each rod fluorinated. Iron consists of a plurality of nano-fluorinated iron particles having a diameter of 30 nm.
  4. 如权利要求1所述的锂离子电池正极复合材料，其特征在于，所述锂离子电池正极复合材料由多个氟化铁颗粒及多个碳纳米管组成，所述碳纳米管在所述锂离子电池正极复合材料中的质量百分比为1-10%。 The positive electrode composite material for a lithium ion battery according to claim 1, wherein the lithium ion battery positive electrode composite material is composed of a plurality of iron fluoride particles and a plurality of carbon nanotubes, wherein the carbon nanotubes are in the lithium The mass percentage in the ionic battery positive electrode composite is 1-10%.
  5. 一种锂离子电池正极复合材料的制备方法，包括： A preparation method of a lithium ion battery positive electrode composite material, comprising:
    提供一碳纳米管原料以及一HF溶液；Providing a carbon nanotube raw material and an HF solution;
    将所述碳纳米管原料分散于所述HF溶液中，形成一第一悬浊液；Dispersing the carbon nanotube raw material in the HF solution to form a first suspension;
    提供一FeCl3溶液，并将所述FeCl3溶液与所述第一悬浊液混合，得到一沉淀物FeF3∙3H2O-CNTs；以及Providing a FeCl 3 solution, and mixing the FeCl 3 solution with the first suspension to obtain a precipitate FeF 3 ∙3H 2 O-CNTs;
    将所述沉淀物分离提纯，并热处理所述沉淀物，从而获得所述锂离子电池正极复合材料。The precipitate was separated and purified, and the precipitate was heat-treated to obtain the lithium ion battery positive electrode composite.
  6. 如权利要求5所述的锂离子电池正极复合材料的制备方法，其特征在于，所述FeCl3溶液为通过将FeCl3.6H2O颗粒溶解于一溶剂中制备而成，且所述溶剂为去离子水、甲醇、乙醇、丙酮、***中的一种或几种。The method for preparing a positive electrode composite material for a lithium ion battery according to claim 5, wherein the FeCl 3 solution is prepared by dissolving FeCl 3 .6H 2 O particles in a solvent, and the solvent is One or more of deionized water, methanol, ethanol, acetone, and diethyl ether.
  7. 如权利要求5所述的锂离子电池正极复合材料的制备方法，其特征在于，所述FeCl3溶液通过滴加的方式逐滴滴入所述第一悬浊液中与所述第一悬浊液混合。The method for preparing a positive electrode composite material for a lithium ion battery according to claim 5, wherein the FeCl 3 solution is dropped into the first suspension and the first suspension by dropping. Liquid mixing.
  8. 如权利要求5所述的锂离子电池正极复合材料的制备方法，其特征在于，所述第一悬浊液与所述FeCl3溶液按照HF与FeCl3的摩尔浓度比大于3：1混合。The method for preparing a positive electrode composite material for a lithium ion battery according to claim 5, wherein the first suspension and the FeCl 3 solution are mixed at a molar concentration ratio of HF to FeCl 3 of more than 3:1.
  9. 如权利要求5所述的锂离子电池正极复合材料的制备方法，其特征在于，所述碳纳米管与所述FeCl3溶液中FeCl3的质量比为0.007：1～0.08：1。The cathode 5 of the method of preparing a composite material as claimed in claim, wherein the mass of the carbon nanotubes in a solution of FeCl 3 FeCl 3 ratio of 0.007: 1 to 0.08: 1.
  10. 如权利要求5所述的锂离子电池正极复合材料的制备方法，其特征在于，所述热处理的温度为120℃-170℃，热处理的时间8-10小时。 The method for preparing a positive electrode composite material for a lithium ion battery according to claim 5, wherein the heat treatment temperature is from 120 ° C to 170 ° C, and the heat treatment time is from 8 to 10 hours.
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