Dense electrode fabric having multi-layer micro-nano structure, manufacturing method therefor, and electrochemical device

Abstract

Disclosed in the present invention are a multi-layer micro-nano dense electrode fabric, a manufacturing method therefor, and an electrochemical device. In the present invention, a multi-layer micro-nano structure is manufactured on a surface of a carbon nano material conductive fiber by means of electrostatic spinning and liquid phase coating methods, and the conductive fiber is used to prepare a densely arranged alternating electrode fabric by using a weaving method. The fabric has a high specific surface area, and the thickness of the fabric does not exceed 0.1 mm. The fabric is loaded with a nano-particle electrochemical oxidation catalyst, is used for wastewater treatment by an electrolytic method, is made into a wastewater treatment device, has the characteristics such as high water flux, low energy consumption, low cost, bending resistance, and rubbing resistance, is suitable for various liquid-phase electrolytic water purification devices, and is also suitable for indoor gas pollutant elimination and infectious disease pathogen inactivation. The technology meets a wide range of market demands.

Description

Dense electrode fabric with multi-layer micro-nano structure and its manufacturing method and electrochemical device Technical Field

[0001] The present invention belongs to the field of electrochemical redox reaction materials and devices, and in particular relates to a dense electrode fabric with a multi-level micro-nano structure, a manufacturing method thereof, and an electrochemical device. Background Art

[0002] Improving technologies for removing pollutants from industrial wastewater and exhaust gases is crucial for long-term sustainable industrial development, including green development, establishing environmentally friendly manufacturing, and promoting energy conservation and carbon reduction. Currently, industrial wastewater is often treated using plate-type electrochemical oxidation reaction cells, which consist of alternating stainless steel, aluminum, and other metal plates. Wastewater flows layer by layer between the positive and negative metal electrodes in a laminar flow. An electric field is applied perpendicular to the flow of water, degrading pollutants in the water due to the current, ultimately eliminating them. However, these methods suffer from limitations such as slow degradation rates and low costs.

[0003] In order to increase the degradation rate, the existing technology has designed various catalysts for different electrochemical reactions. In order to improve the reaction efficiency of the catalyst, the catalyst is loaded on the surface of an electrode with a high specific surface area, so that the contact area between the catalyst and the reactant is large, the catalytic reaction efficiency is improved, and the pollutant treatment capacity per unit time, unit energy consumption, and unit electrode mass is increased.

[0004] Fabric-based flexible electrodes offer unique advantages for the fabrication of low-cost, high-throughput, complex-shaped, and large-scale environmental treatment reactors. Carbon-based materials offer corrosion resistance, and fabric electrodes made from these materials offer significant advantages over metal electrodes in terms of corrosion and bending resistance. Currently, the only carbon-based fiber material suitable for spinning is carbon fiber filament, but carbon fiber is expensive and its weaving properties are far inferior to those of organic polymer fibers.

[0005] Summary of the Invention

[0006] Purpose of the invention: The present invention provides a multi-level micro-nano three-dimensional structure dense electrode fabric, its preparation method and electrochemical device. The fabric of the present invention is woven from conductive fibers with a multi-level micro-nano structure on the surface. The catalyst loaded on its surface with a high specific surface area has a much higher electrochemical catalytic efficiency than that of a smooth surface.

[0007] To achieve the above-mentioned purpose, the present invention adopts the following technical route:

[0008] A multi-level micro-nano three-dimensional structure dense electrode fabric includes conductive warp yarns and weft yarns, the conductive warp yarns are organic conductive fibers, and the weft yarns are insulating fibers; insulating warp yarns are arranged between adjacent conductive warp yarns, and adjacent conductive warp yarns are connected in the transverse direction by different collecting electrodes, and adjacent collecting electrodes are respectively connected to the positive and negative electrodes of a power supply; the conductive warp yarns and collecting electrodes are cured and then encapsulated with an insulating coating to obtain a dense electrode fabric.

[0009] Furthermore, the surface of the organic conductive fiber is covered with nanofibers by electrospinning. The nanofibers are organic fibers mixed with nanocarbon black, with a diameter of less than 200 nm. The mixing ratio of nanocarbon black to organic matter in the organic fiber is not more than 10% wt. The organic matter is any one of polyacrylonitrile, polyvinylidene fluoride, polyamide, and polystyrene.

[0010] Furthermore, the organic conductive fiber is a monofilament alternately covered with carbon nanotubes or graphene or a mixture of the two and carbon black / polyurethane slurry prepared by a multi-layer coating method on the surface of a polymer matrix, with a diameter of less than 50 μm and a specific resistance of no more than 1 kΩ / cm.

[0011] Furthermore, the warp yarn refers to a yarn composed of multiple single filaments that is produced by electrospinning and then covering a layer of a mixture of single-walled carbon nanotubes and nanoparticle catalysts with a liquid coating method and then doubling the yarn.

[0012] Furthermore, the nanoparticle catalyst is one or a combination of Co, Co3O4, Ni / MnO, TiO2, ZnO, etc., the mass ratio of the nanoparticle catalyst to the single-walled carbon nanotube is not greater than 50%wt, and the average particle diameter is not greater than 10nm.

[0013] Furthermore, the collector is a flexible collector, which is a polymer film with a thickness not greater than 0.1 mm, one surface of which is coated with aluminum foil and the other surface is insulated, and has a width of 1 to 5 mm.

[0014] Furthermore, the warp yarn is composed of a plurality of single conductive fibers whose surfaces are covered with nanofibers. The conductive fibers constituting the positive electrode or the negative electrode can be designed to be covered with nanoparticles with different loads or not covered with nanofibers.

[0015] The present invention also provides a method for manufacturing a multi-level micro-nano three-dimensional structure dense electrode fabric, comprising the following steps: weaving organic conductive fiber bundles coated with carbon nanotubes or graphene or a mixture of the two on a shuttle loom into a fabric with a certain period, wherein the period is conductive warp yarn, insulating warp yarn, conductive warp yarn, and insulating warp yarn, to form a large-area fabric in which two conductive warp yarns are separated by insulating warp yarns at a certain distance, connecting positive and negative electrodes to the two conductive warp yarns to form an electrochemical dense electrode fabric. Since the electrode spacing can be precisely controlled through the weaving process and the minimum spacing can be less than 1 mm, the fiber electrode has a much higher specific surface area than the planar electrode, and therefore the fabric dense electrode has a much higher electrochemical reaction efficiency than the plane parallel electrode.

[0016] Furthermore, the organic conductive fibers are single-walled carbon nanotubes, graphene, or a mixture of the two coated onto polymer conductive fibers using a coating method. The number of coating layers can be up to 20, with a thickness not exceeding 2 microns. A nanocarbon powder-mixed aqueous polyurethane slurry is applied between the layers to form a bonding layer. The organic fibers can be prepared using the method disclosed in the Chinese invention patent: Highly Conductive Organic Fibers, Conductive Yarns, and Conductive Fiber Structures and Preparation Methods (Publication No. CN113322670A).

[0017] Furthermore, the organic conductive fiber monofilaments are arranged in parallel at a spacing of 2 mm to form a single-layer structure. By unwinding, guiding and winding, 50 to 100 monofilaments pass under the electrospinning needle at a speed of 0.5 to 5 cm per second. After a certain distance, the electrospinning needle is placed under the parallel fibers. 1 to 5 independent liquid-supply electrospinning needles are set on each side. A high DC voltage is applied between the organic conductive fibers and the electrospinning needles, and the positive electrode is added to the electrospinning needles. The electrospinning liquid is injected into the electrospinning needles at a certain flow rate. The electrospinning needles scan left and right at a constant speed above the parallel fibers, and the formed nano-electrospinning evenly covers the surface of the organic conductive fibers.

[0018] Furthermore, the spinning solution is a 5-10 wt% polyacrylonitrile DMF solution, and nano carbon black is added, and the proportion of carbon black in the polyacrylonitrile is 3-10 wt%.

[0019] Furthermore, catalyst nanoparticles are added to a 0.1-0.5% wt. aqueous solution of single-walled carbon nanotubes to form a monodisperse solution. The catalyst can be any one of Co, Co3O4, Ni / MnO, ZnO, TiO2 and any nanoparticles with electrochemical oxidation catalytic activity. The nanoparticles are mixed with the carbon nanotube solution in a mass ratio of 2-10:1, ultrasonically dispersed to form a solution, and then uniformly coated on the surface of the organic conductive fiber monofilament covered by electrospinning by a coating method.

[0020] Furthermore, the organic conductive fibers are combined into bundles using a doubling process, each bundle consisting of 1 to 5 single filaments. The conductive bundles and insulating yarns of the same denier are arranged into warp yarns on a shuttle loom using a warping process. The width of the warp yarn can be designed, and the conductive bundles and insulating yarns are arranged periodically. The distance between the conductive bundles is determined by the number of insulating yarns, and the distance can be designed between 0.5 mm and 2 mm.

[0021] Furthermore, the weft yarn is woven from insulating yarns of the same or different deniers using a plain weave process, and a collecting electrode is arranged every 10 to 20 cm. The electrode is a flat wire with a width of 3 to 8 mm and is covered with metal foil on one side. The collecting electrode acts as the weft and contacts the conductive warp yarns arranged alternately above and below. The conductive layer on the upper surface of the first weft-inserted collecting flat electrode contacts the odd-numbered conductive warp yarns, and the conductive layer on the lower surface of the second weft-inserted collecting flat electrode contacts the even-numbered conductive warp yarns, and so on, to form alternatingly woven warp fiber yarn electrodes.

[0022] Furthermore, the conductive warp yarn and the flat electrode are fixed with conductive carbon paste by a printing method and then encapsulated with insulating polymer paste to form stable contact and insulation.

[0023] Furthermore, a DC voltage and ground are alternately applied to the woven large-area fabric electrode collector to form a densely packed electrochemical planar unit. Several of these planar units are stacked to form an electrochemical device. The stacking spacing is designed based on the specific reactor requirements (water treatment rate, flow rate, pressure, and power consumption), and is typically 0.5 to 5 cm.

[0024] When used for electrochemical oxidation treatment of wastewater, the fabric is secured to an insulating frame, with multiple fabric planes stacked at a programmable spacing. All positive electrodes are connected to the positive terminal of a power supply, and the ground electrode is connected to the ground of the power supply. The stacked fabrics are then secured in a water treatment container, and water flows perpendicularly through the densely packed electrode array of the multi-layer fabric at a programmable flow rate. Direct current is input, and purified water is obtained at the outlet of the water treatment container. The voltage applied to each layer can be the same or different, and is DC, and must not exceed the breakdown voltage of the liquid.

[0025] When used for indoor air purification, the fabric is formed into a single-layer wall covering or curtain product. The positive and negative electrodes are made of high-conductivity conductive fiber bundles. All positive and negative collectors are connected to wiring terminals. When a DC or AC power source is applied to the terminals, pollutants in the air are removed or negative ions are generated, purifying the indoor air. The voltage applied to the different layers can be the same or different, and can be DC or AC. The voltage must not exceed the gas breakdown voltage.

[0026] Beneficial effects: The present invention utilizes a coating method to coat carbon-based nanomaterials on the surface of organic fibers to form a uniform conductive coating. The fibers have good weaving properties and are ideal materials for preparing low-cost flexible fabric electrodes.

[0027] Electrospinning can stably produce large-area nano-organic fibers. This invention combines conductive nanoparticles with electrochemical and photoelectrochemical catalytic nanoparticles with an organic polymer. Using electrospinning, the nanoparticle-loaded submicron conductive organic fibers are sprayed onto the surface of the micron-sized conductive fibers, forming a three-dimensional, multi-scale, high-specific-surface-area composite fiber structure. This invention creatively transforms these conductive fibers into yarns. By tailoring the weaving conditions, a fabric with periodically alternating positive and negative electrodes is created. The spacing between the positive and negative electrodes is adjustable by adjusting the number of insulating warp yarns, with a minimum spacing of less than 1 mm. This allows for the efficient production of high-density, flexible, low-cost, and densely packed electrode materials using high-specific-surface-area fibers, providing a fundamental building block for the design and manufacture of novel electrochemical devices.

[0028] This invention uses electrospinning and liquid-phase coating to create a multi-layered micro-nanostructure on the surface of carbon nanomaterial conductive fibers. This conductive fiber is then woven into a densely packed alternating electrode fabric. This fabric has a high specific surface area and a thickness of no more than 0.1 mm, and is loaded with a nanoparticle electrochemical oxidation catalyst. The fabric exhibits high water flux, low energy consumption, low cost, and excellent bending and rubbing resistance. It is suitable for use in various liquid-phase electrolysis water purification systems, as well as for removing indoor gaseous pollutants and inactivating infectious pathogens. This technology addresses a wide range of market needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of a dense electrode structure.

[0030] Figure 2 is a schematic diagram of the principle of electrospinning and depositing nanofibers on the surface of conductive fibers.

[0031] Figure 3 is a scanning electron microscope photo of nanofibers deposited on the surface of conductive fibers.

[0032] Figure 4 is a schematic diagram of the principle of using dense electrode fabric for sewage treatment.

[0033] FIG5 is a schematic diagram showing the principle of using dense electrode fabric to remove indoor air pollutants. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific examples, but should not be construed as limiting the present invention. Without departing from the spirit and substance of the present invention, modifications or substitutions made to the inventive method, steps or conditions are intended to fall within the scope of the present invention. Experimental methods and reagents for which specific conditions are not specified in the examples are based on conventional conditions in the art.

[0035] Example 1:

[0036] Step 1. Pass the 20D1F continuous nylon filament continuously through three single-walled carbon nanotube slurry (0.2% wt aqueous solution, Chengdu Times Nanomaterials Co., Ltd.) liquid pools and one nano carbon black / aqueous polyurethane slurry (Cabot nano carbon black, 5% wt content in polyurethane, solid content of aqueous polyurethane is 40% wt) liquid pool. After passing through one liquid pool, it passes through an electric drying tube at a temperature of 100-120°C. After the single fiber passes through 6 carbon tube carbon nanotube slurry liquid pools and two carbon black slurries, it passes through 1 to 2 carbon nanotube liquid pools, is dried and rolled up, and a conductive fiber with a resistivity of no more than 5kΩ / cm is obtained.

[0037] Step 2: Arrange the above-mentioned conductive fibers in parallel with an interval of 1 mm. 100 fibers are introduced into the electrospinning chamber respectively using a guide wheel. The fiber array is arranged in a horizontal or vertical direction. The guide wheels are spaced at not less than 2 m. The guide wheels are made of metal materials, the bottom of the rim is covered with conductive rubber, and the guide wheels are grounded.

[0038] Step 3: Place 6 electrospinning needles with an aperture of 0.2 mm in the electrospinning chamber at a spacing of 25 cm, three of which are placed above or to the right of the fiber array, and three are placed below or to the left of the fiber array. The distance between the three electrospinning needles and the fiber array is 10 to 15 cm. The three needles are placed on the actuator and scan back and forth in a direction perpendicular to the fiber array. The three needles are evenly staggered to ensure that the electrospun nanofibers are evenly covered on the surface of the conductive fiber. The three needles in the opposite direction are similarly arranged.

[0039] Step 4: The conductive fibers are pulled by the winding wheel, and all the conductive fibers pass through the electrospinning chamber at the same speed of 5 to 10 cm. A DC voltage of 5 to 20 kV is applied to the electrospinning needle. The electrospinning solution is injected into the electrospinning needle tube. The electrospinning solution is a polyacrylonitrile / DMF solution with a molecular weight of 150 kDa and a concentration of 9% wt. 5% wt of nano-conductive carbon black is added to the polyacrylonitrile. The injection speed of the electrospinning solution is 1 ml / h. The electrospinning needle scans the surface of the conductive fiber array for spinning at a scanning speed of 3 to 5 cm.

[0040] Step 5: The conductive fiber coated with nanofibers is coated with single-walled carbon nanotubes and catalyst nanoparticles under similar conditions to step 1. The catalyst is an aqueous solution of Co nanoparticles with an average diameter of 6 nanometers and a concentration of 0.1 mg / ml, which is mixed with a 0.2 mg / ml aqueous solution of carbon nanotubes. After the conductive fiber passes through 1 to 5 liquid pools, it is dried and rolled up.

[0041] Step 6: The conductive fibers are combined into bundles of three monofilaments using a doubling technique. This is then woven on a double-shuttle loom to create a dense electrode fabric. The conductive bundles are used as warp yarns, alternating between conductive and insulating warp yarns. Three to five insulating warp yarns are placed between the conductive warp yarns. The insulating warp yarns are 20D9F nylon yarns, and the weft yarns are 20D9F nylon yarns. The weft density is set at 20 to 40 yarns per centimeter, with a weft pass of 10 to 20 cm. A flat current-collecting weft electrode is passed through the other shuttle. The electrode is a nylon flat wire with a width of 3 to 5 mm and one surface covered with aluminum foil with a thickness of 1 to 5 μm. The flat wire is 30 to 100 μm thick. The top surface of the flat current-collecting weft electrode contacts the odd-numbered conductive warp yarns, while the bottom surface of the other flat current-collecting weft electrode contacts the even-numbered conductive warp yarns. This process is repeated to create a dense electrode fabric of the desired width and length.

[0042] Step 7: The woven dense electrode fabric is screen-printed on the surface of the collecting weft electrodes. The carbon paste bonds the conductive warp yarns to the conductive layer on the flat collecting weft electrodes. The carbon paste is narrower than the flat collecting weft electrodes. After drying, the flat collecting weft electrodes are coated with a 20-50 μm thick layer of water-based polyurethane using a printing method. After drying, the fabric is rolled up to form the finished dense electrode fabric.

[0043] Step 8: Bond the dense electrode fabric to a fixed frame designed to be smaller than the fabric width. Stack and seal several fixed frames to form an electrochemical reactor, which is then connected to the water inlet and outlet. Connect each layer of odd-numbered conductive warp yarn collectors to the positive terminal with a wire, and each layer of even-numbered conductive warp yarn collectors to the negative terminal with a wire. Connect the positive and negative electrodes of all the stacked layers with separate wires, then connect them to a DC power supply. Apply a DC voltage of 5 to 15V. Pass the treated sewage through the water inlet, determine the flow rate and pressure based on the sewage pollutant concentration, and adjust the voltage to obtain clean water with organic pollutants removed at the outlet.

[0044] Example 2:

[0045] Step 1: Same as Example 1.

[0046] Step 2: Same as in Example 1.

[0047] Step 3: Same as Example 1.

[0048] Step 4: Same as Example 1.

[0049] Step 5: The conductive fiber coated with nanofibers is coated with a few layers of small-diameter mechanically exfoliated graphene and catalyst nanoparticles under similar conditions to step 1. The catalyst is an aqueous solution of TiO2 nanoparticles with an average diameter of 3 nanometers and a concentration of 0.1 mg / ml, mixed with a 0.2 mg / ml aqueous solution of carbon nanotubes. After the conductive fiber passes through 1 to 5 liquid pools, it is dried and rolled up.

[0050] Step 6: Same as Example 1.

[0051] Step 7: Use screen printing to coat the woven dense electrode fabric with quick-drying conductive carbon glue on the surface of the collecting weft electrode. The carbon glue will bond the conductive warp yarn to the conductive layer on the surface of the flat collecting weft electrode. The width of the carbon glue is lower than that of the flat collecting weft electrode. After drying, it is rolled up to form the finished dense electrode fabric.

[0052] Step 8: Bond the dense electrode fabric to a fixed frame designed to be smaller than the fabric width. Stack and seal several fixed frames to form an electrochemical reactor, which is then connected to the air inlet and outlet. Connect each layer of odd-numbered conductive warp yarn collectors to the positive terminal with a wire, and each layer of even-numbered conductive warp yarn collectors to the negative terminal with a wire. Connect the positive and negative electrodes of all the stacked layers with separate wires, then connect them to a DC power supply. Apply a DC voltage of 5 to 15V. Pass the gas to be treated through the water inlet. Determine the flow rate and pressure based on the concentration of the gaseous pollutants. Adjust the voltage to obtain gas with organic pollutants removed at the outlet.

[0053] Example 3:

[0054] Step 1: Same as Example 1.

[0055] Step 2: Same as in Example 1.

[0056] Step 3: Same as Example 1.

[0057] Step 4: Same as Example 1.

[0058] Step 5: The conductive fiber coated with nanofibers is coated with single-walled carbon nanotubes and catalyst nanoparticles under similar conditions to step 1. The catalyst is an aqueous solution of ZnO nanoparticles with an average diameter of 3 nanometers and a concentration of 0.1 mg / ml, which is mixed with a 2 mg / ml aqueous solution of carbon nanotubes. After the conductive fiber passes through 1 to 5 liquid pools, it is dried and rolled up.

[0059] Step 6: Same as Example 1.

[0060] Step 7: Same as in Example 2.

[0061] Step 8. Connect the odd-numbered conductive warp yarn collector of the single-layer dense electrode fabric to the positive terminal with a wire, and connect the even-numbered conductive warp yarn collector of the single-layer to the negative terminal with a wire. Connect the positive and negative terminals to an AC power source, adjust the frequency, and the dense electrode fabric will produce high-concentration oxygen negative ions, which will purify the air, increase the indoor negative ion content, and play a role in health care.

Claims

1. A multi-level micro-nano three-dimensional structure dense electrode fabric, comprising conductive warp yarns and weft yarns, characterized in that, The conductive warp yarns are organic conductive fibers, and the weft yarns are insulating fibers; insulating warp yarns are arranged between adjacent conductive warp yarns, and adjacent conductive warp yarns are respectively connected by different collectors in the transverse direction, and adjacent collectors are respectively connected to the positive and negative electrodes of the power supply; the conductive warp yarns and the collectors are encapsulated with an insulating coating after curing to form a dense electrode fabric.

2. The multi-level micro-nano three-dimensional structure dense electrode fabric according to claim 1, characterized in that, The surface of the organic conductive fiber is covered with nanofibers by electrospinning. The nanofibers are organic fibers mixed with carbon black nanoparticles, with a diameter less than 200 nm. The mixing ratio of carbon black nanoparticles to organic matter in the organic fibers is not more than 10% wt, and the organic matter is any one of polyacrylonitrile, polyvinylidene fluoride, polyamide, and polystyrene.

3. The multi-level micro-nano three-dimensional structure dense electrode fabric according to claim 1, characterized in that The organic conductive fiber is a single filament alternately covered with carbon nanotubes or graphene or a mixture of both, and carbon black / polyurethane slurry on the surface of a polymer matrix by a multi-layer coating method, with a diameter less than 50 μm and a specific resistance not more than 1 kΩ / cm.

4. A multi-level micro-nano three-dimensional structure dense electrode fabric according to claim 2, characterized in that The warp yarn is a yarn composed of multiple single filaments formed by doubling after electrospinning and then covering a mixture of single-walled carbon nanotubes and nanoparticle catalysts by a liquid-phase coating method.

5. A multi-level micro-nano three-dimensional structure dense electrode fabric according to claim 4, characterized in that, The nanoparticle catalyst is one or a combination of Co, Co3O4, Ni / MnO, TiO2, ZnO, etc. Its mass ratio to single-walled carbon nanotubes is not more than 50% wt, and the average particle diameter is not more than 10 nm.

6. The multi-level micro-nano three-dimensional structure dense electrode fabric according to claim 1, characterized in that The collector is a flexible collector, which is a polymer film with a thickness not more than 0.1 mm. One surface is coated with aluminum foil, and the other surface is insulated, with a width of 1-5 mm.

7. A multi-level micro-nano three-dimensional structure dense electrode fabric according to claim 1, characterized in that The warp yarn is composed of multiple single conductive fibers covered with nanofibers on the surface. The conductive fibers forming the positive or negative electrode can be designed to cover different nanoparticles or not cover nanofibers.

8. The manufacturing method of the multi-layered micro-nano three-dimensional structure dense electrode fabric according to any one of claims 1-7, characterized in that, It includes the following steps: The warp yarns are woven in a cycle, and the cycle is conductive warp yarn, insulating warp yarn, conductive warp yarn, insulating warp yarn; after inserting the weft, adjacent conductive warp yarns are respectively connected by different collectors in the transverse direction, and adjacent collectors are respectively connected to the positive and negative electrodes of the power supply; the conductive warp yarns and the collectors are encapsulated with an insulating coating after curing to obtain a dense electrode fabric.

9. An electrochemical device, characterized in that it is prepared by the following steps: laminating the dense electrode fabric according to any one of claims 1-7 to form an electrochemical device.

10. A reactor for electrochemically catalyzing liquids or gases, characterized in that, Using the electrochemical device according to claim 9.

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