CN114023924A - Preparation method of current collector-free silicon-based negative electrode and fiber lithium ion battery - Google Patents

Preparation method of current collector-free silicon-based negative electrode and fiber lithium ion battery Download PDF

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CN114023924A
CN114023924A CN202111284288.6A CN202111284288A CN114023924A CN 114023924 A CN114023924 A CN 114023924A CN 202111284288 A CN202111284288 A CN 202111284288A CN 114023924 A CN114023924 A CN 114023924A
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silicon
negative electrode
current collector
dispersion liquid
array
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CN114023924B (en
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帅波
徐雄文
王志斌
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Hunan Lifang New Energy Science and Technology 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • 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
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    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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 provides a preparation method of a silicon-based negative electrode without a current collector and a fiber lithium ion battery, wherein the method comprises the following steps: sequentially immersing the spinnable carbon nanotubes arranged in the array into an acid solution and a silicon-based nano material dispersion liquid while drawing a film by the array, spraying a polymer dispersion liquid, twisting and collecting to obtain the current-collector-free silicon-based negative electrode. The invention takes the array carbon nanotube film as the substrate, and uniformly loads the active silicon-based nano material among the pores formed by lapping the carbon nanotubes by an interface self-assembly method, thereby being beneficial to improving the gram volume of the cathode. The twisted carbon nano tube three-dimensional net structure can effectively relieve the expansion of silicon, and the use of a current collector is avoided, so that the energy density and the cycle performance of the lithium ion battery are remarkably improved, and the gram capacity of the silicon-based negative electrode without the current collector is 987-2753 mAh/g; the energy density of the battery is 380-420 Wh/Kg, and after the battery is cycled for 200 times, the capacity retention rate is 73-93%.

Description

Preparation method of current collector-free silicon-based negative electrode and fiber lithium ion battery
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a preparation method of a current collector-free silicon-based negative electrode and a fiber lithium ion battery.
Background
With the development of social economy, textile batteries are widely applied to portable and wearable electronic products, and the current mainstream direction is to manufacture fiber lithium ion batteries, the diameters of which can reach tens of microns to hundreds of microns, so that the fiber lithium ion batteries can be easily woven into wearable and breathable textiles, and the power requirements of various wearable electronic products are met.
The current collector of the negative electrode is a copper wire, and the loaded active substances are graphite, hard carbon, silicon-based materials and the like. When graphite (gram capacity 370mAh/g) is used as the active material, the energy density of the battery is low due to the low gram capacity of graphite and the current collector occupies a part of the volume and mass; when silicon (with a gram volume of 3600mAh/g) and a silicon-based material are used as active substances, the cycle performance of the battery is poor due to excessive volume expansion of the silicon material in the charging and discharging processes.
Disclosure of Invention
In view of this, the present invention provides a method for preparing a current collector-free silicon-based negative electrode and a fiber lithium ion battery, where the silicon-based negative electrode does not need to use a current collector, and can effectively improve the energy density of the lithium ion battery.
The invention provides a preparation method of a current collector-free silicon-based negative electrode, which comprises the following steps:
sequentially immersing the spinnable carbon nanotubes arranged in an array into an acid solution and a silicon-based nano material dispersion liquid while drawing a film by the array, spraying a polymer dispersion liquid, twisting and collecting to obtain a current collector-free silicon-based negative electrode;
the acid solution is a mixed solution of concentrated sulfuric acid and concentrated nitric acid with the volume ratio of 2.5-3.2: 1;
the silicon nano material in the silicon-based nano material dispersion liquid is selected from one or more of silicon, silicon oxide, silicon alloy and silicon-based materials;
the polymer in the polymer dispersion liquid is one or more of polyacrylic acid, polyvinylidene fluoride, polyvinyl alcohol, polyethylene glycol, styrene butadiene rubber, polyethylene and polypropylene.
In the invention, the acid solution is a mixed solution of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3: 1.
In the invention, the concentration of the silicon-based nano material dispersion liquid is 0.01-5 wt%.
In the present invention, the concentration of the polymer dispersion is 0.01 to 6 wt%.
In the invention, the diameter of the silicon-based nano material is 5-50 nm. In a specific embodiment, the silicon-based nanomaterial dispersion is selected from a nano silicon oxide dispersion with a particle size of 10nm and a concentration of 2 wt%; or nano silicon dispersion liquid with the particle size of 15nm and the concentration of 0.8 wt%; or nano ferrosilicon dispersion liquid with the grain diameter of 20nm and the concentration of 1.0 wt%; or nano silicon dispersion liquid with the particle size of 5nm and the concentration of 4 wt%; or nano silicon dispersion liquid with the particle size of 5nm and the concentration of 2wt percent.
In the invention, the array width of the spinnable carbon nano tubes arranged in the array is 5-300 mm. In particular embodiments, the width is 50mm, 40mm, 100mm or 70 mm.
In the present invention, the dispersing agent in the silicon nanomaterial dispersion liquid is selected from cationic surfactants;
the cationic surfactant is selected from one or more of amine salts, heterocycles and xanthates;
the solvent in the silicon-based nano material dispersion liquid is selected from ethanol.
In the present invention, the solvent in the polymer dispersion is selected from water or a volatile organic solvent.
In the invention, the rotating speed of the twisting motor is 50-200 rpm. In particular embodiments, the motor speed for twisting is 50rpm, 80rpm, 60rpm, or 100 rpm.
In the invention, the diameter of the silicon-based negative electrode without the current collector is 50-300 mu m. In specific embodiments, the current collector-less silicon-based negative electrode has a diameter of 150 μm, 50 μm, 95 μm, 55 μm, or 80 μm.
Fig. 1 is a schematic flow chart of the preparation of a current collector-free silicon-based negative electrode according to the present invention; as can be seen from fig. 1, the spinnable carbon nanotube array is fixed on a sample stage 1, a carbon nanotube film 2 is pulled out to a twisting device 6, the width of the film layer is 10-100 μm, and the film passes through a soaking device 3, a soaking device 4 and a spraying device 5 in sequence in the film pulling process; the twisting device 6 is a device for mutually winding raw material wires into a wire, the carbon nanotube film is twisted by the twisting device 6 to obtain a negative electrode 7 without a current collector, and the negative electrode 7 is collected into a coil by the collecting roller 8.
In the invention, the silicon-based negative electrode without the current collector can be twisted continuously to obtain rope-like fibers, and the liquid can be woven into composite fibers with a net structure, so that the application of the composite fibers in the fields of lithium ion batteries and the like is expanded.
The invention provides a fiber lithium ion battery which comprises a silicon-based negative electrode without a current collector, which is prepared by the preparation method of the technical scheme.
A fiber lithium ion battery comprises a positive electrode, a diaphragm, electrolyte, a packaging body and the negative electrode, wherein the diaphragm is used for separating the positive electrode from the negative electrode, and the packaging body is used for installing the positive electrode, the negative electrode, the diaphragm and the electrolyte.
The invention provides a preparation method of a current collector-free silicon-based negative electrode, which comprises the following steps: sequentially immersing the spinnable carbon nanotubes arranged in the array into an acid solution and a silicon-based nano material dispersion liquid while drawing a film by the array, spraying a polymer dispersion liquid, twisting and collecting to obtain the current-collector-free silicon-based negative electrode. According to the invention, the array carbon nanotube film is used as a substrate, the active silicon nano material is uniformly loaded among the pores formed by overlapping the carbon nanotubes by an interface self-assembly method, so that the gram capacity of the negative electrode is improved, and the twisted carbon nanotube three-dimensional network structure can effectively relieve the expansion of silicon, thereby obviously improving the energy density and the cycle performance of the lithium ion battery; the carbon nano tubes sequentially crosslinked by twisting can form a high-electric-conductivity heat-conducting network, have high modulus and toughness, are favorable for forming good interface contact with the active silicon-based nano material, and are not easy to fall off, so that the rate capability of the lithium ion battery is improved. The experimental results show that: the gram capacity of the silicon-based negative electrode without the current collector is 987-2753 mAh/g; the energy density of the lithium ion battery is 380-420 Wh/Kg, and after the battery is cycled for 200 times, the capacity retention rate is 73-93%.
Drawings
Fig. 1 is a schematic flow diagram of the preparation of a current collector-free silicon-based negative electrode of the present invention, wherein 1 is a sample stage, 2 is a carbon nanotube film, 3 is an acid solution soaking device, 4 is a silicon nanomaterial dispersion soaking device, 5 is a spraying device, 6 is a twisting device, 7 is a current collector-free silicon-based negative electrode, and 8 is a collecting roller;
fig. 2 is a graph showing a cycle performance test of the lithium ion battery prepared in example 1 of the present invention.
Detailed Description
In order to further illustrate the present invention, the following will describe in detail the preparation method of a current-collector-free silicon-based negative electrode and the fiber lithium ion battery provided by the present invention with reference to the examples, but they should not be construed as limiting the scope of the present invention.
Preparatory examples
The detailed preparation process of the spinnable carbon nanotube array comprises the following steps:
introducing mixed gas (Ar + 6% H) into a quartz tube furnace2) And pure ethylene with a flow rate of 100sccm, wherein the mixed gas is used as a carrier gas, the pure ethylene is used as a carbon source, and Al is used2O3And (10nm)/Fe (1.0nm) film is used as a catalyst, the temperature is kept at 750 ℃, and the reaction is carried out for 15min, so as to obtain the spinnable carbon nanotube array.
Example 1
A spinnable carbon nanotube array with the array width of 50mm is adopted, a carbon nanotube film is obtained through array film drawing, the film is immersed into concentrated sulfuric acid/concentrated nitric acid solution with the proportion of 3:1 while the film is drawn, then the film is immersed into nano silicon oxide dispersion liquid with the particle size of 10nm and the concentration of 2 wt%, finally polyacrylic acid dispersion liquid with the particle size of 0.1 wt% is sprayed, and twisting is carried out at the rotating speed of a rotating motor of 50rpm, so that a current collector-free negative electrode with the diameter of 80 mu m can be obtained.
And drying the obtained negative electrode without the current collector, and assembling the negative electrode without the current collector and a metal lithium wire into a fiber lithium ion half-cell, wherein the gram capacity of the fiber lithium ion half-cell is 987 mAh/g.
92.5 wt% of lithium cobaltate, 2.5 wt% of Super-P, 5 wt% of polyvinylidene fluoride and N-methyl pyrrolidone are mixed into slurry, an aluminum wire with the diameter of 60 mu m is soaked in the slurry and is uniformly pulled out, and the slurry is dried in an air atmosphere at 120 ℃ and vacuum-dried at 80 ℃ for 24 hours in sequence to be used as a positive electrode.
Preparing an electrolyte: 1.1mol/L lithium hexafluorophosphate (LiPF)6) The electrolyte solution was dissolved in a mixed solvent of dimethyl carbonate (DMC), Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and diethyl carbonate (DEC) (DMC: EC: DEC mass ratio: 3:5:1:2) to obtain an electrolyte solution.
And after the capacity allowance of the negative electrode is ensured to be 15%, the positive electrode and the negative electrode are subjected to membrane coating (Celgard 2325), twisting, electrolyte injection and packaging to obtain the fiber lithium ion battery. The energy density was 380 Wh/kg. After the battery was cycled 200 times, the capacity retention rate was 93%.
Example 2
A spinnable carbon nanotube array with the array width of 40mm is adopted, a carbon nanotube film is obtained through array film drawing, the film is immersed into concentrated sulfuric acid/concentrated nitric acid solution with the proportion of 3:1 while the film is drawn, then the film is immersed into nano silicon dispersion liquid with the particle size of 15nm and the concentration of 0.8 wt%, finally polyacrylic acid dispersion liquid with the particle size of 0.2 wt% is sprayed, and twisting is carried out at the rotating speed of a rotating motor of 80rpm, so that a current collector-free negative electrode with the diameter of 55 mu m can be obtained.
And drying the obtained negative electrode without the current collector, and assembling the negative electrode without the current collector and a metal lithium wire into a fiber lithium ion half-cell, wherein the gram capacity of the fiber lithium ion half-cell is 2125 mAh/g.
The preparation process of the positive electrode and the electrolyte is the same as that of example 1 (the loading amount of the positive electrode active material is 85% of the negative electrode capacity), and the energy density of the fiber lithium ion battery obtained by twisting, injecting and packaging is 405 Wh/kg. After the battery was cycled 200 times, the capacity retention was 77%.
Example 3
A spinnable carbon nanotube array with the array width of 100mm is adopted, a carbon nanotube film is obtained through array film drawing, the film is immersed into concentrated sulfuric acid/concentrated nitric acid solution with the proportion of 3:1 while the film is drawn, then the film is immersed into nano ferrosilicon alloy dispersion liquid with the particle size of 20nm and the concentration of 1.0 wt%, finally polyacrylic acid dispersion liquid with the particle size of 1.0 wt% is sprayed, and twisting is carried out on the dispersion liquid at the rotating speed of a rotating motor of 60rpm, so that a current collector-free negative electrode with the diameter of 95 mu m can be obtained.
And drying the obtained negative electrode without the current collector, and assembling the negative electrode without the current collector and a metal lithium wire into a fiber lithium ion half-cell, wherein the gram capacity of the fiber lithium ion half-cell is 1535 mAh/g.
The preparation process of the anode and the electrolyte is the same as that of example 1 (the loading amount of the anode active material is 85% of the cathode capacity), and the energy density of the fiber lithium ion battery obtained by twisting, injecting and packaging is 390 Wh/kg. After the battery is cycled for 200 times, the capacity retention rate is 76%.
Example 4
A spinnable carbon nanotube array with the array width of 70mm is adopted, a carbon nanotube film is obtained through array film drawing, the film is immersed into concentrated sulfuric acid/concentrated nitric acid solution with the proportion of 3:1 while the film is drawn, then the film is immersed into nano silicon dispersion liquid with the particle size of 5nm and the concentration of 4 wt%, finally polyacrylic acid dispersion liquid with the particle size of 1.5 wt% is sprayed, and twisting is carried out at the rotating speed of a rotating motor of 50rpm, so that the current collector-free negative electrode with the diameter of 150 mu m can be obtained.
The obtained negative electrode without the current collector is dried and then assembled with a metal lithium wire to form a fiber lithium ion battery, the gram capacity of the fiber lithium ion battery is 2753mAh/g,
the preparation process of the positive electrode and the electrolyte is the same as that of example 1 (the loading amount of the positive electrode active material is 85% of the negative electrode capacity), and the energy density of the obtained fiber lithium ion battery is 420 Wh/kg. After the battery is cycled for 200 times, the capacity retention rate is 73%.
Example 5
A spinnable carbon nanotube array with the array width of 70mm is adopted, a carbon nanotube film is obtained through array film drawing, the film is immersed into concentrated sulfuric acid/concentrated nitric acid solution with the proportion of 3:1 while the film is drawn, then the film is immersed into nano silicon dispersion liquid with the particle size of 5nm and the concentration of 2 wt%, finally polyacrylic acid dispersion liquid with the particle size of 1.0 wt% is sprayed, and twisting is carried out at the rotating speed of a rotating motor of 100rpm, so that a current collector-free negative electrode with the diameter of 50 mu m can be obtained.
And drying the obtained negative electrode without the current collector, and assembling the negative electrode without the current collector and a metal lithium wire into a fiber lithium ion half-cell, wherein the gram capacity of the fiber lithium ion half-cell is 1618 mAh/g.
The preparation process of the anode and the electrolyte is the same as that of example 1 (the loading amount of the anode active material is 85% of the capacity of the cathode), and the energy density of the fiber lithium ion battery obtained by twisting, injecting and packaging is 400 Wh/kg. After the battery is cycled for 200 times, the capacity retention rate is 88 percent.
From the above embodiment, the invention provides a preparation method of a current collector-free silicon-based negative electrode, which includes the following steps: sequentially immersing the spinnable carbon nanotubes arranged in the array into an acid solution and a silicon-based nano material dispersion liquid while drawing a film by the array, spraying a polymer dispersion liquid, twisting and collecting to obtain the current-collector-free silicon-based negative electrode. According to the invention, the array carbon nanotube film is used as a substrate, the active silicon nano material is uniformly loaded among the pores formed by overlapping the carbon nanotubes by an interface self-assembly method, so that the gram capacity of the negative electrode is improved, and the twisted carbon nanotube three-dimensional network structure can effectively relieve the expansion of silicon, thereby obviously improving the energy density and the cycle performance of the lithium ion battery; the carbon nano tubes sequentially crosslinked by twisting can form a high-electric-conductivity heat-conducting network, have high modulus and toughness, are favorable for forming good interface contact with the active silicon nano material, and are not easy to fall off, so that the rate capability of the lithium ion battery is improved. The experimental results show that: the gram capacity of the non-collector silicon negative electrode is 987-2753 mAh/g; the energy density of the lithium ion battery is 380-420 Wh/Kg, and after the battery is cycled for 200 times, the capacity retention rate is 73-93%.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. A preparation method of a current collector-free silicon-based negative electrode comprises the following steps:
sequentially immersing the spinnable carbon nanotubes arranged in an array into an acid solution and a silicon-based nano material dispersion liquid while drawing a film by the array, spraying a polymer dispersion liquid, twisting and collecting to obtain a current collector-free silicon-based negative electrode;
the volume ratio of the acid solution is 2.5-3.2: 1, mixed solution of concentrated sulfuric acid and concentrated nitric acid;
the silicon nano material in the silicon nano material dispersion liquid is selected from one or more of silicon, silicon oxide, silicon alloy and silicon-based materials;
the polymer in the polymer dispersion liquid is one or more of polyacrylic acid, polyvinylidene fluoride, polyvinyl alcohol, polyethylene glycol, styrene butadiene rubber, polyethylene and polypropylene.
2. The method according to claim 1, wherein the silicon-based nanomaterial dispersion has a concentration of 0.01 to 5 wt%.
3. The method according to claim 1, wherein the polymer dispersion has a concentration of 0.01 to 6 wt%.
4. The preparation method according to claim 1, wherein the diameter of the silicon-based nanomaterial is 5-50 nm.
5. The preparation method according to claim 1, wherein the spinnable carbon nanotubes in the array have an array width of 5-300 mm.
6. The method according to claim 1, wherein the dispersing agent in the silicon-based nanomaterial dispersion liquid is selected from a cationic surfactant;
the cationic surfactant is selected from one or more of amine salts, heterocycles and xanthates;
the solvent in the silicon-based nano material dispersion liquid is selected from ethanol.
7. The method according to claim 1, wherein the solvent in the polymer dispersion is selected from water and volatile organic solvents.
8. The method according to claim 1, wherein the motor speed for the twisting is 50 to 200 rpm.
9. The preparation method according to claim 1, wherein the diameter of the current collector-free silicon-based negative electrode is 50-300 μm.
10. The fiber lithium ion battery is characterized by comprising the current collector-free silicon-based negative electrode prepared by the preparation method of any one of claims 1 to 9.
CN202111284288.6A 2021-11-01 2021-11-01 Preparation method of silicon-based negative electrode without current collector and fiber lithium ion battery Active CN114023924B (en)

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