CN109256564B - Carbon nanotube-graphite composite material, lithium-sulfur battery positive electrode material and lithium-sulfur battery - Google Patents

Carbon nanotube-graphite composite material, lithium-sulfur battery positive electrode material and lithium-sulfur battery Download PDF

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Publication number
CN109256564B
CN109256564B CN201811051020.6A CN201811051020A CN109256564B CN 109256564 B CN109256564 B CN 109256564B CN 201811051020 A CN201811051020 A CN 201811051020A CN 109256564 B CN109256564 B CN 109256564B
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lithium
carbon nanotube
composite material
positive electrode
sulfur battery
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CN109256564A (en
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孙晓刚
郑典模
蔡满园
聂艳艳
陈珑
潘鹤政
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Henan Kelaiwei Nano Carbon Material Co ltd
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Jiangxi Kelaiwei Carbon Nano Materials Co ltd
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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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • 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
    • 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

Abstract

The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a carbon nanotube-graphite composite material, a lithium sulfur battery positive electrode material and a lithium sulfur battery. The invention provides a carbon nanotube-graphite composite material, which is prepared by preparing raw materials comprising a carbon nanotube, polyimide chopped fibers, a forming auxiliary agent, a defibering agent, a dispersing agent and a polar organic solvent through forming, carbonization, graphitization and rolling in sequence; the carbon nanotube-graphite composite material has pores. The embodiment result shows that the lithium-sulfur battery cathode material prepared from the composite material can be used for preparing the lithium-sulfur battery with the specific capacity of 470mAh/g after 200 cycles under the rate of 1C.

Description

Carbon nanotube-graphite composite material, lithium-sulfur battery positive electrode material and lithium-sulfur battery
Technical Field
The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a carbon nanotube-graphite composite material and a preparation method thereof, a lithium-sulfur battery positive electrode material and a preparation method thereof, and a lithium-sulfur battery.
Background
The sulfur has abundant reserves in the earth, is environment-friendly and pollution-free, and has higher theoretical specific capacity and energy density, so the sulfur can be used as a battery positive electrode active material. When sulfur is used as an active material, a positive electrode sheet is usually supported on a current collector and assembled with a negative electrode and an electrolyte to form a lithium-sulfur battery. Most of the current collectors for the positive electrode of the lithium-sulfur battery prepared at present are aluminum foil materials, and the lithium-sulfur battery prepared by using the materials has the advantages of rapid capacity attenuation and unsatisfactory cycle stability.
Disclosure of Invention
The invention aims to provide a carbon nanotube-graphite composite material which is used as a current collector to prepare a lithium-sulfur battery with good cycle stability.
In order to achieve the above purpose, the invention provides the following technical scheme:
the invention provides a carbon nanotube-graphite composite material, which is prepared by preparing raw materials comprising a carbon nanotube, polyimide chopped fibers, a forming auxiliary agent, a defibering agent, a dispersing agent and a polar organic solvent through forming, carbonization, graphitization and rolling in sequence;
the carbon nanotube-graphite composite material has pores.
Preferably, the mass ratio of the carbon nanotubes to the polyimide chopped fibers is 1: 1-7;
the mass ratio of the polyimide chopped fibers to the fluffing agent is 1: 0.005 to 0.01;
the mass ratio of the carbon nano tube to the dispersing agent is 1: 0.005 to 0.01;
the mass ratio of the total mass of the carbon nano tube and the polyimide chopped fiber to the forming auxiliary agent is 1: 0.004-0.01.
Preferably, the forming aid comprises a binder and a flocculating agent;
the binder comprises polyacrylate and/or polyvinyl alcohol;
the flocculating agent comprises cationic polyacrylamide and/or anionic polyacrylamide.
Preferably, the pore diameter of the pores of the carbon nanotube-graphite composite material is 3-100 nm, and the specific surface area is 15-30 m2The porosity is 50-60%, and the surface resistance is 3-15 omega/□.
The invention provides a preparation method of the carbon nano tube-graphite composite material in the technical scheme, which comprises the following steps:
(1) shearing a mixture comprising carbon nanotubes, polyimide chopped fibers, a defibering agent, a dispersing agent and a polar organic solvent to obtain mixed slurry;
(2) mixing the mixed slurry obtained in the step (1) with a forming aid, and forming to obtain a carbon nanotube-polyimide non-woven fabric;
(3) and (3) sequentially carbonizing, graphitizing and rolling the carbon nanotube-polyimide non-woven fabric obtained in the step (2) to obtain the carbon nanotube-graphite composite material.
Preferably, in the step (3), the carbonization temperature is 1000-1200 ℃, and the carbonization time is 3-8 h;
the graphitization temperature is 2800-3000 ℃, and the graphitization time is 24-48 h;
the rolling pressure is 100-120 kN/m.
The invention provides a positive electrode material of a lithium-sulfur battery, which comprises a current collector, a polysulfide barrier layer and an active material positioned between the current collector and the polysulfide barrier layer;
the current collector is the carbon nanotube-graphite composite material or the carbon nanotube-graphite composite material prepared by the preparation method in the technical scheme;
the active material includes elemental sulfur;
the polysulfide barrier layer comprises carbon nanotube-aramid nonwoven fabric.
Preferably, the active material accounts for 10-30% of the total mass of the positive electrode material of the lithium-sulfur battery.
The invention provides a preparation method of the lithium-sulfur battery positive electrode material, which comprises the following steps:
and coating the slurry containing the active material on the single surface of the carbon nanotube-graphite composite material or the carbon nanotube-graphite composite material prepared by the preparation method in the technical scheme, then paving the carbon nanotube-aramid non-woven fabric layer on the surface of the slurry layer, and performing hot pressing to obtain the lithium-sulfur battery cathode material.
The invention provides a lithium-sulfur battery, which comprises a positive electrode shell, a positive electrode, a diaphragm, a negative electrode shell and electrolyte; the positive electrode is the positive electrode material of the lithium-sulfur battery in the technical scheme or the positive electrode material of the lithium-sulfur battery prepared by the preparation method in the technical scheme.
The invention provides a carbon nanotube-graphite composite material, which is prepared by preparing raw materials comprising a carbon nanotube, polyimide chopped fibers, a forming auxiliary agent, a defibering agent, a dispersing agent and a polar organic solvent through forming, carbonization, graphitization and rolling in sequence; the carbon nanotube-graphite composite material has pores. According to the invention, the polyimide chopped fibers are used as raw materials, and are carbonized and graphitized, then the polyimide chopped fibers are converted into graphite, and the graphite is matched with the carbon nano tube to form the composite material with a pore structure, so that the active component can be attached to the surface and in the pores of the composite material, the loading capacity is improved, the stability of the combination between the active component and the composite material is improved, and the improvement of the cycle stability of the lithium-sulfur battery is facilitated. The embodiment result shows that the lithium-sulfur battery cathode material prepared from the composite material can be used for preparing the lithium-sulfur battery with the specific capacity of 470mAh/g after 200 cycles under the rate of 1C.
Drawings
FIG. 1 is a schematic structural diagram of a positive electrode material for a lithium-sulfur battery according to the present invention; wherein 1 is a carbon nanotube-graphite composite material; 2 is a positive electrode active material; 3 is a polysulfide barrier layer;
fig. 2 is a graph comparing cycle performance of the lithium sulfur batteries of example 1 and comparative example 1.
Detailed Description
The invention provides a carbon nanotube-graphite composite material, which is prepared by preparing raw materials comprising a carbon nanotube, polyimide chopped fibers, a forming auxiliary agent, a defibering agent, a dispersing agent and a polar organic solvent through forming, carbonization, graphitization and rolling in sequence;
the carbon nanotube-graphite composite material has pores.
The raw materials for preparing the carbon nanotube-graphite composite material comprise carbon nanotubes, wherein the carbon nanotubes are preferably multiwalled carbon nanotubes, the diameters of the carbon nanotubes are preferably 30-150 nm, more preferably 45-125 nm, and further preferably 50-100 nm; the length of the carbon nanotube is preferably 5 to 10 μm, more preferably 6 to 9 μm, and further preferably 7 to 8 μm.
The raw materials for preparing the carbon nanotube-graphite composite material comprise polyimide chopped fibers, wherein the diameter of the polyimide chopped fibers is preferably 10-14 mu m, more preferably 11-13 mu m, and further preferably 12 mu m; the length is preferably 3 to 5mm, more preferably 3 to 4mm, and further preferably 4 mm.
The raw materials for preparing the carbon nanotube-graphite composite material comprise a forming aid, wherein the forming aid preferably comprises a binder and a flocculating agent, and the binder preferably comprises polyacrylate and/or polyvinyl alcohol, and more preferably polyacrylate. The flocculating agent preferably comprises a cationic polyacrylamide and/or an anionic polyacrylamide, more preferably a cationic polyacrylamide. The mass ratio of the binder to the flocculating agent is preferably 1: 0.8 to 1.2, more preferably 1: 0.9 to 1.1, most preferably 1: 1.
The raw materials for preparing the carbon nanotube-graphite composite material comprise a fluffer, wherein the fluffer preferably comprises polyethylene oxide or sodium dodecyl sulfate (SDBS).
The raw material for preparing the carbon nanotube-graphite composite material comprises a dispersing agent, wherein the dispersing agent preferably comprises Sodium Dodecyl Sulfate (SDS) or polyvinylpyrrolidone (PVP).
The raw materials for preparing the carbon nanotube-graphite composite material comprise a polar organic solvent, wherein the polar organic solvent preferably comprises ethanol or Dimethylformamide (DMF).
In the present invention, the mass ratio of the carbon nanotubes to the polyimide chopped fibers is preferably 1:1 to 7, more preferably 1:2 to 6, and still more preferably 1:3 to 5. The mass ratio of the polyimide chopped fibers to the fluffing agent is preferably 1: 0.005 to 0.01; more preferably 1: 0.006-0.009, preferably 1: 0.007-0.008. The mass ratio of the carbon nanotubes to the dispersant is preferably 1: 0.005 to 0.01; more preferably 1: 0.006-0.009, preferably 1: 0.007-0.008. The mass ratio of the total mass of the carbon nanotubes and the polyimide chopped fibers to the forming aid is preferably 1: 0.004 to 0.01, more preferably 1: 0.005 to 0.009, and more preferably 1: 0.006 to 0.008.
The carbon nanotube-graphite composite material provided by the invention has pores, and the pore diameter of the pores is preferably 3-100 nm, more preferably 3-80 nm, and further preferably 3-75 nm; the specific surface area of the carbon nanotube-graphite composite material is preferably 15-30 m2A more preferable range is 18 to 27 m/g2A concentration of 20 to 25m2(ii) in terms of/g. The porosity of the carbon nanotube-graphite composite material is preferably 50-60%, more preferably 52-58%, and still more preferably 54-55%. The surface resistance of the carbon nanotube-graphite composite material is preferably 3-15 omega/□, more preferably 3-10 omega/□, and still more preferably 3-6 omega/□. The strength of the carbon nano tube-graphite composite material is 0.12-0.18 kg/mm2。
In the invention, the thickness of the carbon nanotube-graphite composite material is preferably 0.03-0.1 mm, more preferably 0.05-0.08 mm, and still more preferably 0.06-0.07 mm.
The invention provides a preparation method of the carbon nano tube-graphite composite material in the technical scheme, which comprises the following steps:
(1) shearing a mixture comprising carbon nanotubes, polyimide chopped fibers, a defibering agent, a dispersing agent and a polar organic solvent to obtain mixed slurry;
(2) mixing the mixed slurry obtained in the step (1) with a forming aid, and forming to obtain a carbon nanotube-polyimide non-woven fabric;
(3) and (3) sequentially carbonizing, graphitizing and rolling the carbon nanotube-polyimide non-woven fabric obtained in the step (2) to obtain the carbon nanotube-graphite composite material.
The method comprises the step of shearing a mixture comprising the carbon nano tube, the polyimide chopped fibers, the defibering agent, the dispersing agent and the polar organic solvent to obtain mixed slurry. In the present invention, the method for preparing the mixed slurry preferably includes:
and shearing the mixture of the polyimide chopped fiber dispersion liquid and the carbon nanotube dispersion liquid to obtain mixed slurry.
In the present invention, the polyimide chopped fiber dispersion liquid includes polyimide chopped fibers, a debonding agent, and a polar organic solvent, and the mass ratio of the polyimide chopped fibers to the polar organic solvent is preferably 1: 100-200, more preferably 1: 120-180, preferably 1: 130 to 170.
In the present invention, the preparation method of the polyimide chopped fiber dispersion preferably includes mixing the polyimide chopped fibers, the debonding agent, and the polar organic solvent, and then standing. The standing time is preferably 10-30 min, and more preferably 15-25 min.
In the present invention, the alcohol dispersion liquid containing carbon nanotubes comprises carbon nanotubes, a dispersant and a polar organic solvent, and the mass ratio of the carbon nanotubes to the polar organic solvent is preferably 1: 200-300, more preferably 1: 230 to 280, preferably 1: 240-275. The invention has no special requirements on the preparation method of the carbon nano tube alcohol dispersion liquid, and the components are mixed.
The mixing mode of the polyimide chopped fiber dispersion liquid and the carbon nanotube dispersion liquid is not particularly required, and the method is well known by the technical personnel in the field. In the invention, the shearing rate is preferably 1200-2000 r/min, more preferably 1400-1800 r/min, and still more preferably 1500-1700 r/min; the shearing time is preferably 30-60 min, more preferably 40-55 min, and still more preferably 45-50 min. According to the invention, the mixed slurry is preferably prepared under the above conditions, so that the components can be fully mixed, and the carbon nanotube-graphite composite material with good conductivity can be obtained.
After the mixed slurry is obtained, the mixed slurry is preferably mixed with a forming auxiliary agent and then formed to obtain the carbon nano tube-polyimide non-woven fabric. The invention has no special requirements on the mixing mode of the mixed slurry and the forming auxiliary agent, and adopts the mode which is well known by the technical personnel in the field. In the invention, the forming mode is preferably vacuum filtration, and the pressure of the vacuum filtration is preferably 0.08-0.12 MPa, and more preferably 0.08-0.1 MPa.
After the carbon nanotube-polyimide non-woven fabric is obtained, the carbon nanotube-polyimide non-woven fabric is sequentially carbonized, graphitized and rolled to obtain the carbon nanotube-graphite composite material.
In the invention, the carbonization temperature is preferably 1000-1200 ℃, more preferably 1050-1180 ℃, and further preferably 1100-1150 ℃; the carbonization time is preferably 3-8 h, more preferably 4-7 h, and further preferably 5-6 h. The carbonization is preferably carried out under anaerobic conditions, and the anaerobic conditions are preferably realized under the protection of nitrogen. In the invention, the rate of raising the temperature to the temperature required by carbonization is preferably 100-200 ℃/h, more preferably 120-180 ℃, and further preferably 125-175 ℃/h. The carbon nanotube-polyimide non-woven fabric is carbonized, polyimide chopped fibers in the non-woven fabric are decomposed at high temperature, and hydrogen atoms and oxygen atoms in the polyimide chopped fibers are removed to obtain the carbon component.
After carbonization, the invention graphitizes the carbonized material. In the invention, the graphitization temperature is preferably 2800-3000 ℃, more preferably 2850-2970 ℃, and further preferably 2900-2950 ℃; the graphitization time is preferably 24-48 h, more preferably 28-46 h, and more preferably 30-42 h. In the present invention, the graphitization is preferably performed under the protection of nitrogen. In the invention, the rate of raising the temperature from the carbonization temperature to the required graphitization temperature is preferably 100-200 ℃/h, more preferably 120-180 ℃/h, and still more preferably 125-175 ℃/h. The invention graphitizes the carbonized material, and can improve the conductivity of the carbon nano tube-graphite composite material.
After graphitization, the graphitized material is rolled by the method so as to improve the compactness and strength of the material structure. In the invention, the rolling pressure is preferably 100-120 kN/m, more preferably 105-118 kN/m, and still more preferably 108-115 kN/m. The invention has no special requirements on the rolling time and times, so that the carbon nano tube-graphite composite material with the thickness can be obtained.
The invention provides a positive electrode material of a lithium-sulfur battery, which comprises a current collector, a polysulfide barrier layer and an active material positioned between the current collector and the polysulfide barrier layer;
the current collector is the carbon nanotube-graphite composite material or the carbon nanotube-graphite composite material prepared by the preparation method in the technical scheme;
the active material includes elemental sulfur;
the polysulfide barrier layer comprises carbon nanotube-aramid nonwoven fabric.
The active material provided by the invention comprises a sulfur simple substance, wherein the sulfur simple substance is preferably sulfur powder, and the particle size of the sulfur powder is preferably 30-80 nm, more preferably 40-60 nm; the purity of the sulfur powder is preferably more than or equal to 99%.
In the present invention, the active material preferably further includes carbon black and polyvinylidene fluoride, and the carbon black is preferably super carbon black. The invention has no special requirement on the mass ratio of the elemental sulfur, the carbon black and the polyvinylidene fluoride, and the mass ratio of the elemental sulfur, the carbon black and the polyvinylidene fluoride is preferably 1: (0.1-0.2): (0.08 to 0.15), more preferably 1: (0.12-0.15): (0.1-0.12). In the invention, the active material preferably accounts for 10-30% of the total mass of the lithium-sulfur battery positive electrode material, more preferably 15-25%, and still more preferably 20-25%.
The active material is positioned between the current collector and the polysulfide barrier layer, and the carbon nano tube-graphite composite material serving as the current collector has a pore structure, so that the active material can be attached to the surface and in pores of the current collector.
The invention provides a lithium-sulfur battery positive electrode material which comprises a polysulfide barrier layer, wherein the polysulfide barrier layer comprises carbon nano tube-aramid non-woven fabrics. In the invention, the carbon nanotube-aramid nonwoven fabric has a pore structure, and the pore diameter of the pores is preferably 2-110 nm, more preferably 2-80 nm, and further preferably 2-50 nm. The thickness of the carbon nano tube-aramid non-woven fabric is preferably 0.01-0.1 mm, more preferably 0.03-0.08 mm, and further preferably 0.05-0.07 mm. The carbon nanotube-aramid fiber non-woven fabric is preferably used as a polysulfide barrier layer, so that the shuttle effect of sulfur can be effectively inhibited.
The invention provides a preparation method of the lithium-sulfur battery positive electrode material, which comprises the following steps:
and coating the slurry containing the active material on the single surface of the carbon nanotube-graphite composite material or the carbon nanotube-graphite composite material prepared by the preparation method in the technical scheme, then paving the carbon nanotube-aramid fiber non-woven fabric layer on the surface of the slurry layer, and performing hot pressing to obtain the lithium-sulfur battery cathode material.
In the present invention, the slurry preferably includes an active material and a solvent, and the solvent preferably includes N-methylpyrrolidone. The invention has no special requirement on the dosage of the solvent, and can obtain slurry suitable for coating. The preparation method of the slurry has no special requirements, and the active material and the solvent are preferably mixed and then are subjected to uniform ball milling. In the invention, the ball milling speed is preferably 200-300 r/min, more preferably 220-250 r/min; the time for ball milling is preferably 6-10 h, more preferably 7-8 h.
The invention has no special requirements on the coating mode and the coating amount of the slurry, and the mass percentage of the active material in the positive electrode material of the lithium-sulfur battery can reach the range of the technical scheme by adopting a mode well known by the technical personnel in the field.
After coating, the carbon nano tube-aramid fiber non-woven fabric layer is paved on the surface of the slurry layer. In the present invention, the method for preparing the carbon nanotube-aramid nonwoven fabric preferably includes:
shearing a mixture comprising carbon nanotubes, aramid fibers, a defibering agent, a dispersing agent and a polar organic solvent to obtain carbon nanotube-aramid mixed slurry;
and mixing the carbon nanotube-aramid fiber mixed slurry with a forming auxiliary agent, and forming to obtain the carbon nanotube-aramid fiber non-woven fabric.
In the present invention, the method for preparing the carbon nanotube-aramid mixed slurry preferably includes:
mixing and pulping the para-aramid chopped fiber dispersion liquid and the para-aramid pulp fiber dispersion liquid to obtain aramid fiber pulp;
and mixing the aramid fiber slurry with the carbon nano tube alcohol dispersion liquid and sodium dodecyl sulfate to obtain the carbon nano tube-aramid fiber mixed slurry.
In the invention, the para-aramid chopped fiber dispersion liquid preferably comprises para-aramid chopped fibers, sodium dodecyl benzene sulfonate and water, and the mass ratio of the para-aramid chopped fibers to the sodium dodecyl benzene sulfonate to the water is preferably 1: (0.005-0.01): (200-400), more preferably 1: (0.006-0.009): (220-360), and more preferably 1: (0.007-0.008): (240-320).
In the invention, the diameter of the para-aramid chopped fiber is preferably 10-14 μm, more preferably 11-13 μm, and further preferably 12 μm; the length is preferably 3 to 5mm, more preferably 3 to 4mm, and further preferably 4 mm. The para-aramid chopped fibers are commercially available products well known to those skilled in the art.
In the present invention, the form of the para-aramid chopped fiber dispersion preferably includes the steps of:
mixing the para-aramid chopped fibers with water, and then adding sodium dodecyl benzene sulfonate into the mixed material for defibering to obtain the para-aramid chopped fiber dispersion liquid.
In the invention, the defibering temperature is preferably 40-60 ℃, more preferably 45-55 ℃, and further preferably 48-52 ℃; the time for defibering is preferably 15-30 min, more preferably 17-28 min, and still more preferably 20-25 min. The defibration is preferably carried out under stirring in a manner known to the person skilled in the art.
In the present invention, the para-aramid pulp fiber dispersion liquid preferably includes para-aramid pulp fibers, polyethylene oxide, and ethanol, and the mass ratio of the para-aramid pulp fibers, the polyethylene oxide, and the ethanol is preferably 1: (0.005-0.01): (200-400), more preferably 1: (0.006-0.009): (220-360), and more preferably 1: (0.007-0.008): (240-320).
In the invention, the length of the para-aramid pulp fiber is preferably 1.2-2 mm, more preferably 1.4-1.8 mm, and still more preferably 1.5-1.6 mm. The para-aramid pulp fibers are commercially available products well known to those skilled in the art.
In the present invention, the para-aramid pulp fiber dispersion is preferably formed in a manner including the steps of:
mixing the para-aramid pulp fiber with water, and then adding polyethylene oxide (PEO) to the mixture for defibering to obtain the para-aramid pulp fiber dispersion liquid.
In the invention, the defibering temperature is preferably 40-60 ℃, more preferably 45-55 ℃, and further preferably 48-52 ℃; the time for defibering is preferably 15-30 min, more preferably 17-28 min, and still more preferably 20-25 min. The defibration is preferably carried out under stirring in a manner known to the person skilled in the art.
After the para-aramid chopped fiber dispersion liquid and the para-aramid pulp cypress fiber dispersion liquid are obtained, the para-aramid chopped fiber dispersion liquid and the para-aramid pulp cypress fiber dispersion liquid are mixed and then pulped to obtain the aramid fiber pulp. In the invention, when the aramid fiber pulp is prepared, the mass ratio of the para-aramid chopped fibers to the para-aramid pulp fibers is preferably 1 (1-7), more preferably 1 (2-6), and further preferably 1 (3-5); the beating degree of the fiber pulp is preferably 40-60 DEG SR, more preferably 45-58 DEG SR, and further preferably 47-55 DEG SR. The invention has no special requirements on the specific implementation mode of pulping, and the pulping degree can be obtained.
After the aramid fiber slurry is obtained, the aramid fiber slurry is mixed with the carbon nano tube alcohol dispersion liquid and the sodium dodecyl sulfate to obtain the carbon nano tube-aramid fiber mixture. In the present invention, the carbon nanotube alcohol dispersion liquid includes carbon nanotubes, sodium dodecyl sulfate, and ethanol, and the mass ratio of the carbon nanotubes, the sodium dodecyl sulfate, and the ethanol is preferably 1: (0.005-0.01): (200-300), more preferably 1: (0.006-0.009): (220-285), and preferably 1: (0.007-0.008): (240-275).
In the invention, the carbon nanotube is preferably a multi-wall carbon nanotube, and the diameter of the carbon nanotube is preferably 30-150 nm, more preferably 45-125 nm, and still more preferably 50-100 nm; the length of the carbon nanotube is preferably 5 to 10 μm, more preferably 6 to 9 μm, and further preferably 7 to 8 μm. The carbon nanotubes are commercially available products well known to those skilled in the art.
In the present invention, when preparing the carbon nanotube-aramid mixed slurry, the ratio of the mass of the carbon nanotubes to the total mass of the aramid chopped fibers and the aramid pulp fibers is preferably 1: (0.5 to 2), more preferably 1: (0.8-1.8). More preferably 1: (1.0-1.5).
In the invention, the aramid fiber slurry, the carbon nanotube alcohol dispersion liquid and the sodium dodecyl sulfate are preferably mixed under a shearing condition, and the shearing rate is preferably 1200-2000 r/min, more preferably 1500-1800 r/min; the shearing time is preferably 30-60 min, and more preferably 40-55 min.
After the carbon nanotube-aramid fiber slurry is obtained, the carbon nanotube-aramid fiber mixed slurry is mixed with a forming auxiliary agent and then is formed, so that the carbon nanotube-polyimide non-woven fabric is obtained. In the present invention, the forming aid preferably comprises a binder, which preferably comprises polyacrylate and/or polyvinyl alcohol, more preferably polyacrylate, and a flocculating agent. The flocculating agent preferably comprises a cationic polyacrylamide and/or an anionic polyacrylamide, more preferably an anionic polyacrylamide. The mass ratio of the binder to the flocculating agent is preferably 1: 0.8 to 1.2, more preferably 1: 0.9 to 1.1, most preferably 1: 1. In the present invention, the mass ratio of the total mass of the carbon nanotubes and the aramid fibers to the molding aid is preferably 1: 0.004 to 0.01, more preferably 1: 0.005 to 0.009, and more preferably 1: 0.006 to 0.008.
The invention has no special requirement on the mixing mode of the carbon nano tube-aramid fiber mixed slurry and the forming auxiliary agent, and adopts the mode known by the technicians in the field. In the invention, the forming mode is preferably vacuum filtration, and the pressure of the vacuum filtration is preferably 0.08-0.12 MPa, and more preferably 0.08-0.1 MPa. The invention has no special requirements on the specific implementation mode of the vacuum filtration, and the carbon nano tube-aramid non-woven fabric with the thickness of the scheme can be obtained.
The invention has no special requirements on the layer paving mode of the carbon nano tube-aramid non-woven fabric, and the non-woven fabric can be flatly covered on the surface of the active slurry layer.
After the layers are laid, the obtained composite material comprising the carbon nanotube-graphite composite material, the active slurry and the carbon nanotube-aramid non-woven fabric is subjected to hot pressing to obtain the lithium-sulfur battery material. In the invention, the hot pressing temperature is preferably 300-320 ℃, more preferably 305-315 ℃, and further preferably 310-315 ℃; the time for hot pressing is preferably 2-5 min, and more preferably 3-4 min; the hot pressing pressure is preferably 8-10 MPa, more preferably 8.5-10 MPa, and still more preferably 8.5-9.5 MPa. In the present embodiment, the hot pressing is preferably performed by a press vulcanizer.
According to the invention, the carbon nanotube-graphite composite material, the active slurry and the carbon nanotube-aramid non-woven fabric are integrated through hot pressing, so that the lithium-sulfur battery cathode material with better electrochemical performance is obtained.
The invention also provides a lithium-sulfur battery, which comprises a positive electrode shell, a positive electrode, a diaphragm, a negative electrode shell and electrolyte; the positive electrode is the positive electrode material of the lithium-sulfur battery in the technical scheme or the positive electrode material of the lithium-sulfur battery prepared by the preparation method in the technical scheme;
the negative electrode preferably comprises a lithium sheet;
the separator preferably comprises a polypropylene porous film;
the electrolyte preferably comprises LiPF6。
The method for assembling the lithium-sulfur battery has no special requirements, and the lithium-sulfur battery is preferably assembled according to the sequence of the positive electrode shell, the positive electrode, the diaphragm, the negative electrode shell and the electrolyte.
In the above embodiments, the reagents used in the present invention are commercially available products well known to those skilled in the art, unless otherwise specified.
For further explanation of the present invention, the carbon nanotube-graphite composite material, the positive electrode material for lithium sulfur battery, and the lithium sulfur battery according to the present invention will be described in detail with reference to the accompanying drawings and examples, which should not be construed as limiting the scope of the present invention.
Example 1
Preparing a carbon nano tube-graphite composite material:
0.5g of polyimide chopped fibers was dissolved in 100g of ethanol, and 0.005g of polyethylene oxide (PEO) was added as a thinning agent to fully thin the polyimide chopped fibers, thereby obtaining a polyimide chopped fiber slurry.
0.5g of carbon nano tube and 0.005g of SDS are weighed and dissolved in 100g of ethanol, then ultrasonic treatment is carried out for 20min under the condition that the frequency is 80KHz, and then shearing is carried out for 30min under the condition that the rotating speed is 1000r/min, so as to prepare the carbon nano tube dispersion liquid.
And mixing the carbon nano tube dispersion liquid of the polyimide chopped fiber slurry, and then shearing for 30min by a high-speed shearing machine under the condition of 1500r/min to prepare the carbon nano tube-polyimide chopped fiber mixed slurry.
0.008g of polyacrylate and 0.005g of cationic polyacrylamide are added into the mixed slurry of the carbon nanotube-polyimide chopped fibers, and the carbon nanotube-polyimide non-woven fabric is obtained through a vacuum filtration mode.
Under the protection of nitrogen, heating to 1200 ℃ at the speed of 100 ℃/h to carbonize the carbon nanotube-polyimide non-woven fabric, then heating to 2800 ℃ at the heating speed of 100 ℃/h to graphitize, and repeatedly binding by a double-roller binding machine to obtain the carbon nanotube-graphite composite material.
Preparing the carbon nano tube-aramid non-woven fabric:
weighing 0.5g of para-aramid pulp fiber and 0.005g of polyethylene oxide (PEO) to be dispersed in the liquid, standing and soaking for defibering; weighing 0.5g of para-aramid chopped fiber and 0.005g of sodium dodecyl sulfate, dissolving in an ethanol solution, stirring and defibering, mixing the defibered two fibers, and pulping in a pulping machine to obtain the aramid fiber pulp.
0.5g of carbon nano tube and 0.005g of SDS are weighed and dissolved in ethanol, the frequency is 80KHz, the ultrasonic treatment is carried out for 20min, and the shearing is carried out for 30min under the condition that the speed is 1500r/min, thus obtaining the carbon nano tube dispersion liquid.
And mixing the aramid fiber slurry and the carbon nano tube dispersion liquid, and shearing for 30min by using a high-speed shearing machine to prepare the carbon nano tube-aramid fiber mixed slurry.
And adding 0.08g of anionic polyacrylamide into the carbon nanotube-aramid fiber mixed slurry, and performing vacuum filtration to obtain the carbon nanotube/aramid fiber non-woven fabric.
Preparing a multifunctional positive electrode of the lithium-sulfur battery:
weighing 1.4g of active substance sulfur, 0.4g of super carbon black and 0.2g of polyvinylidene fluoride in a proper amount of N-methyl pyrrolidone, and shearing and dispersing to obtain positive active slurry;
the prepared positive active slurry is uniformly coated on one side of the carbon nano tube-graphite composite material in a coating mode.
And (3) sticking the carbon nanotube-graphite composite material coated with the positive active slurry and the carbon nanotube-aramid non-woven fabric together, and performing hot pressing for 3min at the temperature of 300 ℃ and the pressure of 10MPa by using a flat vulcanizing machine to obtain the positive electrode of the lithium-sulfur battery.
Preparation of lithium-sulfur battery:
and (3) dropwise adding electrolyte into the positive electrode shell, the positive electrode, the diaphragm, the negative electrode and the negative electrode shell in sequence to assemble the lithium-sulfur battery.
Examples 2 to 3
A carbon nanotube-graphite composite material, a lithium sulfur battery positive electrode material, and a lithium sulfur battery were prepared in the same manner as in example 1, except for the amounts of raw materials and process parameters, which are specifically listed in table 1.
Comparative example 1
A positive electrode material and a battery were prepared in the same manner as in example 1, except that aluminum foil was used as a current collector.
TABLE 1 EXAMPLES 1-3 raw material usage and Process parameters
Figure BDA0001794549950000121
Figure BDA0001794549950000131
Characterization and results of Performance
The surface resistance of the carbon nanotube-graphite composite material obtained in examples 1 to 3 was measured by a four-probe resistance meter, and the measurement results are shown in table 2;
testing the specific surface area and the aperture of the carbon nanotube-graphite composite material by using a specific surface area analyzer, testing the tensile strength of the material by using a method of hanging weights under a unit sectional area, and testing results are listed in table 2;
TABLE 2 Structure and Performance parameters of the carbon nanotube-graphite composite materials obtained in examples 1 to 3
Figure BDA0001794549950000141
The test results in table 2 show that the carbon nanotube-graphite composite material provided by the invention has good mechanical properties and electrical properties, and is suitable for being used as a current collector of a positive electrode material; in addition, the carbon nanotube-graphite composite material has a pore structure, and a positive electrode active material can be embedded in the pore structure, so that the carbon nanotube-graphite composite material is favorable for improving the loading capacity of the positive electrode active material.
The cycling stability of the lithium sulfur batteries obtained in examples 1 to 3 and comparative example 1 was tested under the condition of a charge-discharge rate of 1C, the test results are shown in FIG. 2 and Table 3, FIG. 2 is a comparison graph of the cycling performance of the batteries obtained in example 1 and comparative example 1, and it can be seen from the graph that the capacity retention rate of the battery obtained in example 1 is about 88% and is significantly higher than the retention rate of the battery capacity of 65% obtained in comparative example 1 after 250 cycles under the rate of 1C.
TABLE 3 electrochemical Performance test results of lithium-sulfur batteries obtained in examples 1 to 3
Figure BDA0001794549950000142
The test results in table 3 show that the carbon nanotube-graphite composite material provided by the invention can be used as a current collector to prepare the positive electrode material of the lithium-sulfur battery, so that the attenuation speed of the specific capacity of the battery can be reduced, and the cycling stability of the lithium-sulfur battery can be improved.
From the above embodiments, the carbon nanotube-graphite composite material provided by the present invention has good pore structure, strength and toughness, and can inhibit the volume expansion effect, and the carbon nanotube-graphite composite material also has excellent conductivity, so as to improve the problem of poor conductivity of elemental sulfur. In addition, the carbon nanotube-aramid fiber non-woven fabric is used as a polysulfide barrier layer of the lithium-sulfur battery positive electrode, so that the shuttle effect of sulfur can be inhibited, and the cycle stability of the lithium-sulfur battery is further improved.
According to the invention, the surface of the lithium belt is coated with the lithium fluoride passive film, so that the oxidation of lithium can be prevented; the lithium fluoride passive film can effectively prevent excessive lithium from reacting with electrolyte to form lithium dendrite in the process of charging and discharging the battery, thereby improving the cycle stability of the lithium ion battery.
The preparation method of the flexible lithium ion battery provided by the invention is simple, easy to control, low in cost and suitable for popularization and application.
Although the present invention has been described in detail with reference to the above embodiments, it is only a part of the embodiments of the present invention, not all of the embodiments, and other embodiments can be obtained without inventive step according to the embodiments, and the embodiments are within the scope of the present invention.

Claims (4)

1. A lithium sulfur battery positive electrode material comprising a current collector, a polysulfide barrier layer, and an active material located between the current collector and the polysulfide barrier layer; the current collector is a carbon nano tube-graphite composite material; the active material is elemental sulfur; the polysulfide barrier layer is carbon nano tube-aramid fiber non-woven fabric;
the carbon nanotube-graphite composite material is prepared by preparing raw materials comprising a carbon nanotube, polyimide chopped fibers, a forming auxiliary agent, a defibering agent, a dispersing agent and a polar organic solvent through forming, carbonization, graphitization and rolling in sequence;
the forming aid comprises a binder and a flocculating agent, wherein the binder comprises polyacrylate and/or polyvinyl alcohol; the flocculating agent comprises cationic polyacrylamide and/or anionic polyacrylamide;
the fluffer comprises polyoxyethylene or sodium dodecyl sulfate;
the dispersing agent comprises sodium dodecyl sulfate or polyvinylpyrrolidone;
the polar organic solvent comprises ethanol or dimethylformamide;
the carbonization temperature is 1000-1200 ℃, and the carbonization time is 3-8 h; the graphitization temperature is 2800-3000 ℃, and the graphitization time is 24-48 h; the rolling pressure is 100-120 kN/m;
the mass ratio of the carbon nano tube to the polyimide chopped fibers is 1: 1-7;
the carbon nanotube-graphite composite material has pores;
the aperture of the pores of the carbon nanotube-graphite composite material is 3-100 nm, and the porosity is 50-60%;
the specific surface area of the carbon nano tube-graphite composite material is 15-30 m2The surface resistance is 3-15 omega/□;
the pore diameter of the pores of the carbon nano tube-aramid non-woven fabric is 2-110 nm; the thickness of the carbon nano tube-aramid non-woven fabric is 0.01-0.1 mm.
2. The positive electrode material for lithium-sulfur batteries according to claim 1, wherein the active material accounts for 10 to 30% of the total mass of the positive electrode material for lithium-sulfur batteries.
3. The method for preparing the positive electrode material for the lithium sulfur battery according to claim 1 or 2, comprising: and coating the slurry containing the active material on one side of the carbon nanotube-graphite composite material, then paving the carbon nanotube-aramid fiber non-woven fabric layer on the surface of the slurry layer, and performing hot pressing to obtain the lithium-sulfur battery cathode material.
4. A lithium-sulfur battery comprises a positive electrode shell, a positive electrode, a diaphragm, a negative electrode shell and electrolyte; the positive electrode is the positive electrode material for the lithium-sulfur battery according to claim 1 or 2 or the positive electrode material for the lithium-sulfur battery prepared by the preparation method according to claim 3.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102146641A (en) * 2011-01-12 2011-08-10 中南大学 Process for manufacturing modified carbon fiber paper by adopting carbon nanotube implanting method
CN105529464A (en) * 2016-01-22 2016-04-27 南京航空航天大学 Lithium-sulfur battery
CN105845972A (en) * 2016-06-01 2016-08-10 复旦大学 Fibrous aqueous lithium ion battery and preparation method thereof
CN106374113A (en) * 2016-10-31 2017-02-01 南昌大学 Method for preparing lithium-sulfur battery by taking graphitized carbon nanotube flexible film as current collector of lithium-sulfur battery
CN106396680A (en) * 2016-09-07 2017-02-15 南昌大学 Preparation method of flexible ultrathin carbon nanotube paper

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103500847B (en) * 2013-10-02 2016-08-17 中国地质大学（武汉） Lithium-sulfur cell additive, positive electrode containing this additive and preparation method thereof
CN107359303A (en) * 2017-07-17 2017-11-17 济南大学 Lithium-sulfur cell modification barrier film and preparation method thereof and the lithium-sulfur cell with the barrier film

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102146641A (en) * 2011-01-12 2011-08-10 中南大学 Process for manufacturing modified carbon fiber paper by adopting carbon nanotube implanting method
CN105529464A (en) * 2016-01-22 2016-04-27 南京航空航天大学 Lithium-sulfur battery
CN105845972A (en) * 2016-06-01 2016-08-10 复旦大学 Fibrous aqueous lithium ion battery and preparation method thereof
CN106396680A (en) * 2016-09-07 2017-02-15 南昌大学 Preparation method of flexible ultrathin carbon nanotube paper
CN106374113A (en) * 2016-10-31 2017-02-01 南昌大学 Method for preparing lithium-sulfur battery by taking graphitized carbon nanotube flexible film as current collector of lithium-sulfur battery

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