CN114361476B - Preparation method and application of gas diffusion electrode - Google Patents
Preparation method and application of gas diffusion electrode Download PDFInfo
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- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims description 8
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims description 8
- 229920001774 Perfluoroether Polymers 0.000 claims description 8
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 8
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Abstract
The invention discloses a preparation method of a gas diffusion electrode and application thereof, wherein the preparation method comprises the following steps: s10, coating conductive polymer dispersion liquid on the surface of a current collecting layer raw material to obtain a current collecting layer; s20, coating a hydrophobic and breathable layer raw material on one side of the current collecting layer to obtain a hydrophobic and breathable layer; s30, coating a catalytic layer raw material on the other side of the current collecting layer to obtain a catalytic layer; s40, carrying out hot pressing treatment on a composite layer material consisting of the hydrophobic and breathable layer, the current collecting layer and the catalytic layer, and then sintering at 200-400 ℃ to obtain the gas diffusion electrode. The conducting polymer is coated on the surface of the raw material of the current collecting layer, and the composite layer material consisting of the hydrophobic and breathable layer, the current collecting layer and the catalytic layer is subjected to hot pressing treatment, so that the conducting polymer among the catalytic layer, the hydrophobic and breathable layer and the current collecting layer is fused and adhered, the interlayer adhesion of the gas diffusion electrode is improved, and the stability of the gas diffusion electrode in high-current density operation under a strong corrosive environment is further enhanced.
Description
Technical Field
The invention relates to the technical field of gas diffusion electrodes, in particular to a preparation method and application of a gas diffusion electrode.
Background
The metal-air battery has the advantages of high energy density, high specific capacity and high use safety, and is a new energy battery with excellent application prospect. The electrochemical oxygen-making/deoxidizing technology is a novel technology for transferring oxygen from the cathode end to the anode end of an electrolytic cell through electrochemical reaction, and has wide development space in industries such as food preservation, medical care and the like. In both technologies, the gas diffusion electrode is the core component of the cell, and plays a critical role in facilitating the transport of gaseous reactants and providing efficient reactive sites.
Because the electrolytes used in both techniques are strongly alkaline, the corresponding gas diffusion electrodes need to have good alkali corrosion resistance, so that the electrodes can still maintain good structural stability in strongly alkaline environments and in high current density operation. The existing gas diffusion electrode is usually combined with the current collecting layer, the catalytic layer and the waterproof and breathable layer only through mechanical action, and the gas diffusion electrode prepared by the method is poor in interlayer adhesion, and is easy to peel off or even fall off between the catalytic layer and the hydrophobic and breathable layer when the gas diffusion electrode is operated in a strong corrosive environment for a long time and at a high current density.
Disclosure of Invention
The invention mainly aims to provide a preparation method and application of a gas diffusion electrode, and aims to solve the problem of poor structural stability of the existing gas diffusion electrode.
In order to achieve the above object, the present invention provides a method for preparing a gas diffusion electrode, comprising the steps of:
s10, coating conductive polymer dispersion liquid on the surface of a current collecting layer raw material, and then drying to obtain a current collecting layer;
s20, coating a raw material of a hydrophobic and breathable layer on one side of the current collecting layer, and then drying to obtain the hydrophobic and breathable layer;
s30, coating a catalytic layer raw material on the other side of the current collecting layer, and then drying to obtain a catalytic layer;
s40, carrying out hot pressing treatment on the composite layer material consisting of the hydrophobic and breathable layer, the current collecting layer and the catalytic layer at 100-150 ℃, and then sintering for 1-3 hours at 200-400 ℃ to obtain the gas diffusion electrode.
Optionally, in step S10:
the current collecting layer is made of metal wire mesh or foam metal; and/or the number of the groups of groups,
the conductive polymer in the conductive polymer dispersion liquid comprises at least one of polyaniline, polypyrrole and polyacetylene; and/or the number of the groups of groups,
the mass of the conductive polymer loaded on the current collecting layer is 1-2.5 mg/cm 2 。
Optionally, before step S20, the method further includes the following steps:
pulverizing and sieving carbon materials, and uniformly mixing the carbon materials with a solvent to obtain a mixed solution;
pulping the mixed solution to obtain carbon material slurry with the particle size smaller than 15 mu m;
adding a hydrophobic polymer and a pore-forming agent into the carbon material slurry, and pulping for 2-5 hours at 12000-20000 rpm to obtain slurry with the particle size smaller than 15 mu m;
and (3) baking the slurry to paste at 50-90 ℃ to obtain the raw material of the hydrophobic and breathable layer.
Optionally, the carbon material comprises at least one of conductive carbon black, carbon nanotubes, and acetylene black; and/or the number of the groups of groups,
the solvent comprises at least one of water, absolute ethyl alcohol, n-propanol and isopropanol; and/or the number of the groups of groups,
the hydrophobic polymer comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, polytrifluorostyrene and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer; and/or the number of the groups of groups,
the pore-forming agent comprises at least one of sodium sulfate, ammonium oxalate, ammonium bicarbonate and lithium carbonate.
Optionally, the mass of the hydrophobic polymer is 40-80% of the mass of the carbon material; and/or the number of the groups of groups,
the mass of the pore-forming agent is 10-20% of the mass of the carbon material.
Optionally, before step S30, the method further includes the following steps:
crushing and sieving the catalyst and the carbon material, and uniformly mixing the catalyst and the carbon material with a solvent to obtain a first solution;
pulping the first solution to obtain mixed slurry with the particle size smaller than 15 mu m;
adding a hydrophobic polymer and a pore-forming agent into the mixed slurry, and pulping for 2-5 hours at 12000-2000 rpm to obtain a catalyst layer slurry with the particle size smaller than 15 mu m;
and baking the catalytic layer slurry to paste at 50-90 ℃ to obtain the catalytic layer raw material.
Optionally, the catalyst comprises a manganese dioxide catalyst; and/or the number of the groups of groups,
the carbon material comprises at least one of conductive carbon black, carbon nanotubes and acetylene black; and/or the number of the groups of groups,
the solvent comprises at least one of water, absolute ethyl alcohol, n-propanol and isopropanol; and/or the number of the groups of groups,
the hydrophobic polymer comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, polytrifluorostyrene and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer; and/or the number of the groups of groups,
the pore-forming agent comprises at least one of sodium sulfate, ammonium oxalate, ammonium bicarbonate and lithium carbonate; and/or the number of the groups of groups,
the mass ratio of the catalyst to the carbon material is 1.5-5: 1, a step of; and/or the number of the groups of groups,
the mass of the hydrophobic polymer is 20-40% of the total mass of the carbon material and the catalyst; and/or the number of the groups of groups,
the mass of the pore-forming agent is 10-20% of the total mass of the carbon material and the catalyst.
Optionally, in step S40:
in the hot pressing treatment, the hot pressing pressure is 1.5-5 MPa, and the hot pressing time is 5-10 min.
Further, the invention also provides a metal-air battery, which comprises the gas diffusion electrode, wherein the gas diffusion electrode is prepared by the preparation method of the gas diffusion electrode.
The invention also provides a method for electrochemically producing oxygen, which takes water and carbon dioxide as reaction raw materials and generates O on an anode by electrolysis 2 At the same time as CO 2 Electrochemical reaction occurs under the action of a cathode catalyst,
wherein the cathode is a gas diffusion electrode, and the gas diffusion electrode is prepared by the preparation method of the gas diffusion electrode.
According to the technical scheme provided by the invention, the conductive polymer is coated on the surface of the current collecting layer raw material to obtain the current collecting layer, then the catalytic layer and the hydrophobic and breathable layer are respectively arranged on two sides of the current collecting layer, and finally the composite layer material (namely the preliminarily formed gas diffusion electrode) formed by the hydrophobic and breathable layer, the current collecting layer and the catalytic layer is subjected to hot pressing treatment, so that the conductive polymer among the catalytic layer, the hydrophobic and breathable layer and the current collecting layer is fused and adhered, the interlayer adhesion of the prepared gas diffusion electrode is improved, and the structural stability of the gas diffusion electrode in a highly corrosive environment and in high-current density operation is further enhanced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other related drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a scanning electron microscope image of a hydrophobic and breathable layer of a gas diffusion electrode prepared in example 1 of the present invention;
FIG. 2 is a Scanning Electron Microscope (SEM) image of a cross section of a gas diffusion electrode according to example 1 of the present invention;
FIG. 3 is a graph showing the voltage-current density relationship in electrochemical oxygen generation/removal in examples 1-4 and comparative example 1 of the present invention;
FIG. 4 is a graph showing the stability test of the present invention in electrochemical oxygen generation/removal in example 1 and comparative example 1.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
In addition, the meaning of "and/or" as it appears throughout includes three parallel schemes, for example "A and/or B", including the A scheme, or the B scheme, or the scheme where A and B are satisfied simultaneously. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be regarded as not exist and not within the protection scope of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Because the electrolytes used in the metal-air battery and the electrochemical oxygen generation/deoxidation technology are all strong alkaline, the corresponding gas diffusion electrode needs to have good alkali corrosion resistance, so that the electrode can still maintain good structural stability when working under the strong alkaline environment with high current density. The existing gas diffusion electrode is usually combined with the current collecting layer, the catalytic layer and the waterproof breathable layer only through mechanical action, and the gas diffusion electrode prepared by the method is poor in interlayer adhesion, and is easy to peel off or even fall off when the catalytic layer and the hydrophobic breathable layer are operated at high current density under a strong corrosive environment for a long time.
In view of the above, the present invention provides a method for preparing a gas diffusion electrode, which aims to provide a gas diffusion electrode with good structural stability, so that the gas diffusion electrode has long service life when being applied to metal-air batteries and electrochemical oxygen production technologies. In one embodiment, the method for preparing the gas diffusion electrode comprises the following steps:
and S10, coating conductive polymer dispersion liquid on the surface of the current collecting layer raw material, and then drying to obtain the current collecting layer.
The current collecting layer is used for conducting current generated in the electrochemical reaction process and supporting the whole gas diffusion electrode, and in the embodiment, the raw material of the current collecting layer is a metal wire mesh or foam metal. Preferably, the raw material of the current collecting layer is a metal wire mesh or foam metal made of nickel, so that the prepared current collecting layer has good supporting effect and corrosion resistance. More preferably, the raw material of the current collecting layer is nickel wire mesh with the mesh number of 20-50 meshes.
In order to make the adhesion between the current collecting layer and the catalytic layer and between the current collecting layer and the hydrophobic and air permeable layer better, in this embodiment, the raw material of the current collecting layer is pretreated. Specifically, the pretreatment step includes: and (3) ultrasonically treating the current collecting layer raw material in acetone for 10-30 min, then ultrasonically treating the current collecting layer raw material in 1mol/L (mol/L is abbreviated as M) hydrochloric acid for 30s, and finally washing the current collecting layer raw material with deionized water. Wherein, the ultrasonic treatment in acetone is used for removing dust and greasy dirt on the surface of the raw material of the current collecting layer. The ultrasonic treatment in hydrochloric acid is used for removing the oxide layer on the surface of the current collecting layer raw material and increasing the surface roughness of the current collecting layer raw material.
In this embodiment, the conductive polymer in the conductive polymer dispersion liquid includes at least one of polyaniline, polypyrrole, and polyacetylene, that is, the conductive polymer may be polyaniline, polypyrrole, polyethylene, a mixture of polypyrrole and polyacetylene, a mixture of polyaniline and polyacetylene, or the like. In a preferred embodiment, the conductive polymer is polyaniline, so that the stability and corrosion resistance of the gas diffusion electrode is improved. The invention does not limit the addition amount of the conductive polymer dispersion liquid, as long as the mass of the conductive polymer loaded on the finally prepared current collecting layer is 1-2.5 mg/cm 2 And (3) obtaining the product.
And step S20, coating a raw material of a hydrophobic and breathable layer on one side of the current collecting layer, and then drying to obtain the hydrophobic and breathable layer.
And step S30, coating a catalytic layer raw material on the other side of the current collecting layer, and then drying to obtain the catalytic layer.
It should be noted that, the present invention is not limited to the sequence between the step S20 and the step S30, and the operation of the step S20 may be performed first, or the step S30 may be performed first.
And S40, carrying out hot pressing treatment on the composite layer material consisting of the hydrophobic and breathable layer, the current collecting layer and the catalytic layer at 100-150 ℃, and then sintering for 1-3 hours at 200-400 ℃ to obtain the gas diffusion electrode.
In this embodiment, in the hot pressing treatment, the hot pressing pressure is 1.5 to 5MPa, the hot pressing time is 5 to 10min, and under this hot pressing condition, the adhesion among the catalytic layer, the hydrophobic and breathable layer, and the current collecting layer is good.
In addition, in this example, the thickness of the finally produced gas diffusion electrode after sintering was 0.3 to 0.6mm. In another embodiment, in the finally produced gas diffusion electrode, the thickness of the hydrophobic gas-permeable layer is 0.2 to 0.3mm. In another embodiment, in the finally produced gas diffusion electrode, the thickness of the catalytic layer is 0.05 to 0.15mm.
In step S10, step S20 and step S30, the temperature of the drying is 50 to 90 ℃. It will be appreciated that in the above steps, the drying temperatures may be selected independently of each other, and may be the same or different. For ease of operation, it is preferably the same.
According to the technical scheme provided by the invention, the conductive polymer is coated on the surface of the current collecting layer raw material to obtain the current collecting layer, then the catalytic layer and the hydrophobic and breathable layer are respectively arranged on two sides of the current collecting layer, and finally the composite layer material (namely the preliminarily formed gas diffusion electrode) formed by the hydrophobic and breathable layer, the current collecting layer and the catalytic layer is subjected to hot pressing treatment, so that the conductive polymer among the catalytic layer, the hydrophobic and breathable layer and the current collecting layer is fused and adhered, the interlayer adhesion of the prepared gas diffusion electrode is improved, and the structural stability of the gas diffusion electrode in a highly corrosive environment and in high-current density operation is further enhanced.
In the gas diffusion electrode, the hydrophobic and breathable layer plays roles of oxygen diffusion, oxygen reduction, electrolyte leakage blocking and the like, and when the gas diffusion electrode is applied to a metal-air battery, for example, when the air humidity is higher than the equilibrium humidity of electrolyte, water diffuses from air to the electrolyte side, so that the electrolyte is diluted, the volume is increased, and the battery shell is gradually broken, so that the electrolyte leakage is caused; when the air humidity is lower than the equilibrium humidity of the electrolyte, the moisture diffuses from the electrolyte to the air side, so that the moisture of the electrolyte is lost, and the electrolyte is gradually dried, thereby causing the failure of the metal-air battery. In addition, the strong alkaline electrolyte absorbs carbon dioxide in the air to cause carbonation, wherein the generated carbonate or bicarbonate crystal particles easily clog the micropores of the gas diffusion electrode, thereby shortening the service life of the gas diffusion electrode. In order to solve the above problems, methods of reducing the pore diameter of the microporous channels in the hydrophobic and gas permeable layer and increasing the thickness of the hydrophobic and gas permeable layer are mainly used at present, but these methods can negatively affect the gas transmission of the gas diffusion electrode, thereby reducing the battery performance; at the same time, carbonation crystallization caused by carbon dioxide can more easily block the microporous channels, thereby further shortening the service life of the gas diffusion electrode.
In view of this, the invention also provides the preparation methods of the raw materials of the hydrophobic and breathable layer and the raw materials of the catalytic layer, and through the selection, the material proportion and the design of the preparation process of the raw materials of the hydrophobic and breathable layer and the raw materials of the catalytic layer, the pore diameter and the distribution of the micropores of the hydrophobic and breathable layer are optimized, and the number of the communication holes is increased, so that the gas transmission performance is further improved on the premise of ensuring the electrolyte permeation prevention capability of the gas diffusion electrode, and the negative influence of the carbonation problem caused by carbon dioxide on the service life of the gas diffusion electrode is effectively slowed down.
Therefore, in the present embodiment, before step S20, the following steps are further included:
and A1, crushing and sieving the carbon material, and uniformly mixing the carbon material with a solvent to obtain a mixed solution.
Pulverizing the carbon material, sieving with a 1000-6000 mesh sieve, mixing the carbon material with a solvent, and carrying out ultrasonic oscillation for 30-60 min to fully and uniformly mix the carbon material to obtain a mixed solution.
Wherein the carbon material includes at least one of conductive carbon black, carbon nanotube and acetylene black, that is, the carbon material may be conductive carbon black, carbon nanotube, acetylene black, a mixture of conductive carbon black and carbon nanotube, or the like. Further, the conductive carbon Black is specifically Vulcan XC-72, BP-2000 or Ketjen-Black. The solvent includes at least one of water, absolute ethanol, n-propanol, and isopropanol.
And A2, pulping the mixed solution to obtain carbon material slurry with the particle size smaller than 15 mu m.
Pulping the mixed solution by using a high-speed shearing machine, pulping for 30-60 min at 8000-12000 rpm until a uniform paste is formed, wherein the particle size of solid particles in the paste is smaller than 15 mu m, and obtaining the carbon material slurry.
And A3, adding a hydrophobic polymer and a pore-forming agent into the carbon material slurry, and pulping for 2-5 hours at 12000-2000 rpm to obtain slurry with the particle size smaller than 15 mu m.
In order to obtain better beating, shearing and mixing effects, in a preferred embodiment, step A3 comprises: the hydrophobic polymer and the pore-forming agent are added into the carbon material slurry drop by drop under the condition of pulping at 8000-12000 rpm, and the slurry with the particle size smaller than 15 mu m is obtained by continuously and alternately pulping for 2-5 hours according to the rotation speeds of 12000, 16000 and 20000 rpm.
Wherein the hydrophobic polymer includes at least one of Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polytrifluorostyrene (PTFS), and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (PFA). Preferably, the hydrophobic polymer is polytetrafluoroethylene. It will be appreciated that to facilitate the dispersion of the hydrophobic polymer, a hydrophobic polymer dispersion is added here.
The pore-forming agent comprises at least one of sodium sulfate, ammonium oxalate, ammonium bicarbonate and lithium carbonate. In order to facilitate the dispersion of the pore-forming agent in the carbon material slurry, the pore-forming agent is preferably pulverized and sieved through a 1000-3000 mesh sieve, and then dispersed in a solvent in which the pore-forming agent cannot be dissolved to form a uniform dispersion, and then added to the carbon material slurry.
It is understood that, according to the different types of the hydrophobic polymer, the pore-forming agent and the carbon material, the addition amounts thereof are correspondingly different, and the specific addition amounts of the hydrophobic polymer, the pore-forming agent and the carbon material are not limited in the invention, and in the embodiment, the mass of the hydrophobic polymer is 40-80% of the mass of the carbon material; and/or the mass of the pore-forming agent is 10-20% of the mass of the carbon material.
And step A4, baking the slurry to paste at 50-90 ℃ to obtain the raw material of the hydrophobic and breathable layer.
In this embodiment, before step S30, the following steps are further included:
and B1, after crushing and sieving the catalyst and the carbon material, uniformly mixing the catalyst and the carbon material with a solvent to obtain a first solution.
In this embodiment, the catalyst comprises a manganese dioxide catalyst. The carbon material includes at least one of conductive carbon black, carbon nanotubes, and acetylene black. Specifically, the conductive carbon Black is Vulcan XC-72, BP-2000 or Ketjen-Black. Further, the mass ratio of the catalyst to the carbon material is 1.5 to 5:1. wherein the solvent comprises at least one of water, absolute ethanol, n-propanol and isopropanol.
And B2, pulping the first solution to obtain mixed slurry with the particle size smaller than 15 mu m.
Pulping the first solution by using a high-speed shearing machine, pulping for 30-60 min at 8000-12000 rpm until a uniform paste is formed, wherein the particle size of solid particles in the paste is smaller than 15 mu m, and obtaining the mixed slurry.
And B3, adding the hydrophobic polymer and the pore-forming agent into the mixed slurry, and pulping for 2-5 hours at 12000-2000 rpm to obtain the catalyst layer slurry with the particle size smaller than 15 mu m.
Specifically, the hydrophobic polymer and the pore-forming agent are added into the mixed slurry drop by drop under the condition of pulping at 8000-12000 rpm, and the slurry is continuously and alternately pulped for 2-5 hours according to the rotational speeds of 12000, 16000 and 20000rpm, so as to obtain the catalyst layer slurry with the particle size smaller than 15 mu m. Wherein the hydrophobic polymer comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, polytrifluorostyrene and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer; and/or the pore-forming agent comprises at least one of sodium sulfate, ammonium oxalate, ammonium bicarbonate and lithium carbonate.
In this embodiment, the mass of the hydrophobic polymer is 20 to 40% of the total mass of the carbon material and catalyst. In another embodiment, the mass of the pore former is 10 to 20% of the total mass of the carbon material and catalyst.
When the conductive polymer in the step S10 is polyaniline, the hydrophobic polymers in the step A3 and the step B3 are Polytetrafluoroethylene (PTFE), and the sintering temperature of the composite layer material is 340-400 ℃, the stability and corrosion resistance of the obtained gas diffusion electrode are better. The specific materials of the carbon material, the solvent, the hydrophobic polymer and the pore-forming agent in steps A1 and A3 and steps B1 and B3 may be the same or different, and are preferably the same for ease of handling.
And B4, baking the catalytic layer slurry to paste at 50-90 ℃ to obtain the catalytic layer raw material.
An example of a method for manufacturing a gas diffusion electrode according to the present invention is given below:
(1) Pulverizing carbon material (at least one of conductive carbon black, carbon nano tube and acetylene black), sieving with a 1000-6000 mesh sieve, mixing with solvent (at least one of water, absolute ethyl alcohol, n-propanol and isopropanol), carrying out ultrasonic vibration for 30-60 min to fully mix the mixture to obtain mixed solution, pulping the mixed solution by using a high-speed shearing machine for 30-60 min at 8000-12000 rpm to obtain carbon material slurry with the particle size smaller than 15 mu m, pulping a hydrophobic polymer (at least one of polytetrafluoroethylene, polyvinylidene fluoride, polytrifluorostyrene and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer) and a pore-forming agent (at least one of sodium sulfate, ammonium oxalate, ammonium bicarbonate and lithium carbonate) into the carbon material slurry (wherein the mass of the hydrophobic polymer is 40-80% of the mass of the carbon material, the mass of the pore-forming agent is 10-20% of the mass of the carbon material) dropwise under the pulping condition of 8000-12000 rpm, and continuously pulping the hydrophobic polymer slurry at 20000 ℃ for 2-5 mu m alternately at the particle size of the temperature of 12000-20000 ℃ to obtain a paste, and baking the paste with the particle size smaller than 50 mu m.
(2) After crushing and sieving a catalyst (manganese dioxide catalyst) and a carbon material (at least one of conductive carbon black, carbon nano tubes and acetylene black), uniformly mixing the crushed and sieved catalyst and a solvent (at least one of water, absolute ethyl alcohol, n-propanol and isopropanol) to obtain a first solution (wherein the mass ratio of the catalyst to the carbon material is 1.5-5:1), pulping the first solution by using a high-speed shearing machine for 30-60 min at 8000-12000 rpm to obtain a mixed slurry with the particle size smaller than 15 mu m, dropwise adding a hydrophobic polymer (at least one of polytetrafluoroethylene, polyvinylidene fluoride, polytrifluorostyrene and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer) and a pore-forming agent (at least one of sodium sulfate, ammonium oxalate, ammonium bicarbonate and lithium carbonate) into the mixed slurry under the pulping condition of 8000-12000 rpm, continuously pulping at 12000, 20000rpm for 2-5 h alternately to obtain a catalyst layer with the particle size smaller than 15 mu m (wherein the mass ratio of the catalyst layer is 40% of the total mass of the catalyst and the catalyst layer is 20-20% of the total mass of the catalyst under the conditions of 40-20% of the catalyst and the total mass of the catalyst layer is baked to obtain the paste.
(3) Ultrasonic treating the raw material of current collecting layer (wire mesh or foam metal) in acetone for 10-30 min, ultrasonic treating in 1mol/L hydrochloric acid for 30s, washing with deionized water, immersing the washed raw material of current collecting layer in conductive polymer dispersion (conductive polymer including polyaniline, polypyrrole and polyacetylene), and drying at 50-90 deg.C to obtain current collecting layer (conductive polymer loaded on current collecting layer has mass of 1-2.5 mg/cm) 2 )。
(4) And coating a hydrophobic and breathable layer raw material on one side of the current collecting layer, and drying at 50-90 ℃ to obtain the hydrophobic and breathable layer.
(5) And coating a catalytic layer raw material on the other side of the current collecting layer, and drying at 50-90 ℃ to obtain the catalytic layer.
(6) And carrying out hot pressing treatment on a composite layer material consisting of the hydrophobic and air-permeable layer, the current collecting layer and the catalytic layer for 5-10 min at the temperature of 100-150 ℃ and the pressure of 1.5-5 MPa, and then sintering for 1-3 h at the temperature of 200-400 ℃ to obtain the gas diffusion electrode with the thickness of 0.3-0.6 mm, wherein the thickness of the hydrophobic and air-permeable layer is 0.2-0.3 mm, and the thickness of the catalytic layer is 0.05-0.15 mm.
Further, the invention also provides a metal-air battery, which comprises a gas diffusion electrode, wherein the gas diffusion electrode is prepared by the preparation method of the gas diffusion electrode. The gas diffusion electrode has good structural stability in a strong corrosive environment and in high-current density operation, has good electrolyte permeation prevention capability and gas transmission performance, and can effectively slow down the negative influence of carbonation problem caused by carbon dioxide on the service life of the gas diffusion electrode, so that the metal-air battery prepared from the gas diffusion electrode has long service life and better battery performance.
In addition, the invention also provides a method for electrochemically preparing oxygen, which takes water and carbon dioxide as reaction raw materials and takes the water and the carbon dioxide as the reaction raw materials in the anodeElectrolytic production of O on electrodes 2 At the same time as CO 2 Electrochemical reaction occurs under the action of a cathode catalyst, wherein the cathode is a gas diffusion electrode, and the gas diffusion electrode is prepared by the preparation method of the gas diffusion electrode. The gas diffusion electrode has good structural stability in a strong corrosive environment and in high-current density operation, has good electrolyte permeation prevention capability and gas transmission performance, and can effectively slow down the negative influence of carbonation problem caused by carbon dioxide on the service life of the gas diffusion electrode, so that the gas diffusion electrode has long service life and better performance when being used as a cathode for electrochemical oxygen production.
The following technical solutions of the present invention will be described in further detail with reference to specific examples and drawings, and it should be understood that the following examples are only for explaining the present invention and are not intended to limit the present invention.
Example 1
(1) Grinding and crushing 4.8g of acetylene black and 8g of Vulcan XC-72, sieving with a 1000-3000 mesh sieve, mixing the mixture with 400mL of isopropanol, carrying out ultrasonic vibration for 60min to fully mix the mixture, obtaining a mixed solution, pulping the mixed solution by using a high-speed shearing machine, pulping the mixed solution at 12000rpm for 45min to obtain carbon material slurry with the particle size smaller than 15 mu m, dropwise adding 25g of 30wt% polytetrafluoroethylene dispersion and 12.5g of 20wt% ammonium oxalate ethanol dispersion into the carbon material slurry (namely, 58.6% of the mass of a hydrophobic polymer and 19.5% of the mass of a pore-forming agent) under the condition of 12000rpm pulping, continuously pulping the slurry at 12000, 16000 and 20000rpm alternately for 2.5h to obtain the slurry with the particle size smaller than 15 mu m, and baking the slurry to a paste at 90 ℃ to obtain the raw material of the hydrophobic breathable layer.
(2) After 10g of manganese dioxide catalyst, 1.2g of acetylene black and 2g of Vulcan XC-72 are crushed and sieved by a 1000-3000 sieve, the crushed materials are uniformly mixed with 400mL of isopropanol to obtain a first solution (namely, the mass ratio of the catalyst to the carbon material is 3.125:1), the first solution is subjected to beating treatment by using a high-speed shearing machine, the beating is carried out for 45min at 12000rpm to obtain a mixed slurry with the particle size of less than 15 mu m, 16g of 30wt% polytetrafluoroethylene dispersion liquid and 12.5g of 20wt% ammonium oxalate ethanol dispersion liquid are dropwise added into the mixed slurry under the condition of beating at 12000rpm, the beating is continuously carried out for 4h alternately according to the rotation speeds of 12000, 16000 and 20000rpm to obtain a catalyst layer slurry with the particle size of less than 15 mu m (namely, the mass of hydrophobic polymer is 36% of the total mass of the carbon material and the catalyst, the mass of the pore-forming agent is 18.9% of the total mass of the carbon material and the catalyst), and the catalyst layer slurry is baked at 90 ℃ to obtain a pasty raw material for the catalyst layer.
(3) Cutting 20 mesh nickel screen to 10cm×10cm size, ultrasonic treating in acetone for 20min, ultrasonic treating in 1mol/L hydrochloric acid for 30s, washing with deionized water, soaking the washed collecting layer material in polyaniline solution, and oven drying at 80deg.C to obtain collecting layer (conductive polymer loaded on the collecting layer has mass of 1.3 mg/cm) 2 )。
(4) And coating a hydrophobic and breathable layer raw material on one side of the current collecting layer, and drying at 60 ℃ to obtain the hydrophobic and breathable layer.
(5) And coating a catalytic layer raw material on the other side of the current collecting layer, and drying at 60 ℃ to obtain the catalytic layer.
(6) And carrying out hot pressing treatment on the composite layer material consisting of the hydrophobic and air-permeable layer, the current collecting layer and the catalytic layer for 10min at 150 ℃ and 3MPa, and then sintering for 2h at 350 ℃ to obtain the gas diffusion electrode with the thickness of 0.4mm, wherein the thickness of the hydrophobic and air-permeable layer is 0.27mm, and the thickness of the catalytic layer is 0.05mm.
Example 2
(1) Grinding and crushing 4.5g of carbon nano tubes and 7.5g of BP-2000, sieving with a 3000-6000 mesh sieve, mixing the ground and crushed carbon nano tubes with 400mL of absolute ethyl alcohol, carrying out ultrasonic vibration for 30min to fully mix the ground and crushed carbon nano tubes with the absolute ethyl alcohol to obtain a mixed solution, pulping the mixed solution by using a high-speed shearing machine for 60min at 8000rpm to obtain carbon material slurry with the particle size smaller than 15 mu m, dropwise adding 40g of 12wt% polyvinylidene fluoride dispersion liquid and 12g of 10wt% ammonium bicarbonate ethanol dispersion liquid into the carbon material slurry (namely, the mass of a hydrophobic polymer is 40% of the mass of the carbon material and the mass of a pore-forming agent is 10% of the mass of the carbon material) under the condition of 8000rpm pulping, continuously carrying out alternate pulping for 5h according to the rotation speeds of 12000, 16000 and 20000rpm to obtain slurry with the particle size smaller than 15 mu m, and baking the slurry to a paste at 50 ℃ to obtain a hydrophobic and breathable layer raw material.
(2) After 9g of manganese dioxide catalyst, 1.5g of acetylene black and 4.5g of BP-2000 are crushed and pass through a 1000-3000 sieve, the crushed materials are uniformly mixed with 400mL of absolute ethyl alcohol to obtain a first solution (namely, the mass ratio of the catalyst to the carbon material is 1.5:1), a high-speed shearing machine is used for beating the first solution, beating is carried out for 45min at 800rpm to obtain mixed slurry with the particle size of less than 15 mu m, 15g of 40wt% polyvinylidene fluoride dispersion liquid and 15g of 50wt% ammonium bicarbonate ethanol dispersion liquid are dropwise added into the mixed slurry under the condition of beating at 8000rpm, beating is continuously carried out for 5h alternately according to the rotation speeds of 12000, 16000 and 20000rpm to obtain catalytic layer slurry with the particle size of less than 15 mu m (namely, the mass of hydrophobic polymer is 40% of the total mass of the carbon material and the catalyst, the mass of the pore-forming agent is 20% of the total mass of the carbon material and the catalyst), and the catalytic layer slurry is baked at 50 ℃ to obtain the raw material of the catalytic layer.
(3) Cutting 30 mesh wire gauze to 10cm×10cm size, ultrasonic treating in acetone for 20min, ultrasonic treating in 1mol/L hydrochloric acid for 30s, washing with deionized water, soaking the washed collector layer material in polyaniline solution, and oven drying at 90deg.C to obtain collector layer (conductive polymer loaded on the collector layer has mass of 1 mg/cm) 2 )。
(4) And coating a hydrophobic and breathable layer raw material on one side of the current collecting layer, and drying at 90 ℃ to obtain the hydrophobic and breathable layer.
(5) And coating a catalytic layer raw material on the other side of the current collecting layer, and drying at 90 ℃ to obtain the catalytic layer.
(6) And carrying out hot pressing treatment on the composite layer material consisting of the hydrophobic and air-permeable layer, the current collecting layer and the catalytic layer for 5min at 100 ℃ and 5MPa, and then sintering for 3h at 200 ℃ to obtain the gas diffusion electrode with the thickness of 0.3mm, wherein the thickness of the hydrophobic and air-permeable layer is 0.2mm, and the thickness of the catalytic layer is 0.06mm.
Example 3
(1) Grinding and crushing 4g of carbon nano tube and 8g of acetylene black, sieving with a 1000-3000 mesh sieve, mixing the carbon nano tube and 400mL of n-propanol, carrying out ultrasonic vibration for 50min to fully mix the mixture to obtain a mixed solution, pulping the mixed solution by using a high-speed shearing machine for 30min at 10000rpm to obtain carbon material slurry with the particle size smaller than 15 mu m, dropwise adding 20g of 48wt% of poly (trifluorostyrene) dispersion and 12g of 20wt% of sodium sulfate ethanol dispersion into the carbon material slurry (namely, the mass of hydrophobic polymer is 80% of the mass of the carbon material, and the mass of pore-forming agent is 20% of the mass of the carbon material) under the condition of 10000rpm pulping, continuously pulping the slurry for 2h alternately according to the rotation speeds of 12000, 16000 and 20000rpm to obtain the slurry with the particle size smaller than 15 mu m, and baking the slurry to the paste at 60 ℃ to obtain the raw material of the hydrophobic and breathable layer.
(2) After 10g of manganese dioxide catalyst, 1g of carbon nano tube and 1g of acetylene black are crushed and pass through a 1000-3000 sieve, the crushed materials are uniformly mixed with 400mL of normal propyl alcohol to obtain a first solution (namely, the mass ratio of the catalyst to the carbon material is 5:1), a high-speed shearing machine is used for beating the first solution for 45min at 10000rpm to obtain mixed slurry with the particle size of less than 15 mu m, 12g of 20wt% of a poly (trifluorostyrene) dispersion and 12g of 10wt% of sodium sulfate ethanol dispersion are dropwise added into the mixed slurry under the condition of beating at 10000rpm, beating is continuously carried out for 2h according to the rotation speed of 12000, 16000 and 20000rpm, so as to obtain catalytic layer slurry with the particle size of less than 15 mu m (namely, the mass of hydrophobic polymer is 20% of the total mass of the carbon material and the catalyst, the mass of the pore-forming agent is 10% of the total mass of the carbon material and the catalyst), and the catalytic layer slurry is baked to paste at 70 ℃ to obtain the catalytic layer raw material.
(3) Cutting nickel foam metal to 10cm×10cm size, ultrasonic treating in acetone for 20min, ultrasonic treating in 1mol/L hydrochloric acid for 30s, washing with deionized water, soaking the washed collector layer material in polyaniline solution, and oven drying at 50deg.C to obtain collector layer (conductive polymer loaded on the collector layer has mass of 2.5 mg/cm) 2 )。
(4) And coating a hydrophobic and breathable layer raw material on one side of the current collecting layer, and drying at 50 ℃ to obtain the hydrophobic and breathable layer.
(5) And coating a catalytic layer raw material on the other side of the current collecting layer, and drying at 50 ℃ to obtain the catalytic layer.
(6) And carrying out hot pressing treatment on the composite layer material consisting of the hydrophobic and breathable layer, the current collecting layer and the catalytic layer for 7min at 120 ℃ and 1.5MPa, and then sintering for 1h at 400 ℃ to obtain the gas diffusion electrode with the thickness of 0.6mm, wherein the thickness of the hydrophobic and breathable layer is 0.3mm, and the thickness of the catalytic layer is 0.15mm.
Example 4
(1) Cutting 20 mesh nickel screen to 10cm×10cm size, ultrasonic treating in acetone for 20min, ultrasonic treating in 1mol/L hydrochloric acid for 30s, washing with deionized water, soaking the washed collecting layer material in polyaniline solution, and oven drying at 80deg.C to obtain collecting layer (conductive polymer loaded on the collecting layer has mass of 1.3 mg/cm) 2 )。
(2) And coating a hydrophobic and breathable layer raw material (a mixture of a carbon material, a hydrophobic polymer, isopropanol and a pore-forming agent) on one side of the current collecting layer, and then drying at 60 ℃ to obtain the hydrophobic and breathable layer.
(3) And coating a catalytic layer raw material (a mixture of a catalyst, a carbon material, a hydrophobic polymer, isopropanol and a pore-forming agent) on the other side of the current collecting layer, and then drying at 60 ℃ to obtain the catalytic layer.
(4) And carrying out hot pressing treatment on the composite layer material consisting of the hydrophobic and breathable layer, the current collecting layer and the catalytic layer for 10min at 150 ℃ and 3MPa, and then sintering for 2h at 350 ℃ to obtain the gas diffusion electrode with the thickness of 0.4mm, wherein the thickness of the hydrophobic and breathable layer is 0.3mm, and the thickness of the catalytic layer is 0.1mm.
Comparative example 1
The procedure was the same as in example 1 (i.e., the current collector surface was not coated with a conductive polymer), except that step (3) was replaced with cutting the 20 mesh nickel screen to a size of 10cm×10cm, then sonicating in acetone for 20min, then sonicating in 1mol/L hydrochloric acid for 30s, finally rinsing with deionized water, and then drying at 80 ℃.
FIG. 1 is a scanning electron microscope image of a hydrophobic and breathable layer of a gas diffusion electrode prepared in example 1 of the present invention;
FIG. 2 is a Scanning Electron Microscope (SEM) image of a cross section of a gas diffusion electrode according to example 1 of the present invention. It can be seen from fig. 1 and 2 that the surface of the gas diffusion electrode prepared by the preparation method of the invention has a plurality of micropores, and meanwhile, the hydrophobic binder existing in the pore canal is distributed among carbon material particles in a thread shape, so that the mechanical strength and the hydrophobicity of the surface of the hydrophobic breathable layer of the gas diffusion electrode are well maintained.
FIG. 3 is a graph showing the voltage-current density relationship in electrochemical oxygen generation/removal in examples 1-4 and comparative example 1 of the present invention. As can be seen from FIG. 3, the gas diffusion electrode prepared by the method of the present invention has excellent performance in electrochemical oxygen generation/removal, and the reaction current density can reach 300mA cm at a voltage of 1.2V -2 . By comparing examples 1-3 with example 4, it is demonstrated that the gas diffusion electrode manufactured by the process for manufacturing a gas diffusion layer and a catalytic layer according to the present invention has a larger current density in an actual electrochemical oxygen generation/removal test, and that the gas diffusion electrode manufactured according to the present invention has a more excellent water-repellent gas permeability, and can ensure sufficient contact of the reaction gas with the interface of the catalytic layer during the electrochemical oxygen generation/removal process. By comparing the embodiment 1 with the comparative example 1, it is demonstrated that the addition of the conductive polymer also improves the performance of the conductive polymer in the electrochemical oxygen generation/removal process to a certain extent, and the current density improvement amplitude of the conductive polymer is correspondingly increased along with the increase of the voltage.
Fig. 4 is a graph showing stability test of the present invention in electrochemical oxygen generation/removal, as can be seen from fig. 4, in the constant voltage long-time electrochemical oxygen generation/removal test of 1.2V voltage, the current density of the gas diffusion electrode manufactured according to the methods of example 1 and comparative example 1 is attenuated to some extent, wherein the gas diffusion electrode of example 1 has a performance attenuation of only 7% in the continuous test of 500 hours, and the gas diffusion electrode of comparative example 1 has an attenuation of 15%, which means that the stability of the gas diffusion electrode is significantly improved by the treatment process of coating the surface of the current collecting layer with the conductive polymer.
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention, but various modifications and variations will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (7)
1. A method of making a gas diffusion electrode comprising the steps of:
s10, coating conductive polymer dispersion liquid on the surface of a current collecting layer raw material, and then drying to obtain a current collecting layer;
s20, after crushing and sieving the carbon material, uniformly mixing the carbon material with a solvent to obtain a mixed solution;
pulping the mixed solution to obtain carbon material slurry with the particle size smaller than 15 mu m; adding a hydrophobic polymer and a pore-forming agent into the carbon material slurry, and pulping for 2-5 hours at 12000-20000 rpm to obtain slurry with the particle size smaller than 15 mu m; baking the slurry to paste at 50-90 ℃ to obtain a raw material of a hydrophobic and breathable layer, coating the raw material of the hydrophobic and breathable layer on one side of the current collecting layer, and then drying to obtain the hydrophobic and breathable layer;
s30, after the catalyst and the carbon material are crushed and sieved, uniformly mixing the catalyst and the carbon material with a solvent to obtain a first solution; pulping the first solution to obtain mixed slurry with the particle size smaller than 15 mu m, adding a hydrophobic polymer and a pore-forming agent into the mixed slurry, and pulping for 2-5 h at 12000-20000 rpm to obtain catalyst layer slurry with the particle size smaller than 15 mu m; baking the catalyst layer slurry to paste at 50-90 ℃ to obtain catalyst layer raw materials, coating the catalyst layer raw materials on the other side of the current collecting layer, and then drying to obtain a catalyst layer;
s40, carrying out hot pressing treatment on a composite layer material formed by the hydrophobic and breathable layer, the current collecting layer and the catalytic layer at 100-150 ℃, and then sintering for 1-3 hours at 200-400 ℃ to obtain a gas diffusion electrode;
wherein, in step S10:
the current collecting layer is made of metal wire mesh or foam metal, the conductive polymer in the conductive polymer dispersion liquid comprises at least one of polyaniline, polypyrrole and polyacetylene, and the mass of the conductive polymer loaded on the current collecting layer is 1-2.5 mg/cm 2 。
2. The method of manufacturing a gas diffusion electrode according to claim 1, wherein the carbon material comprises at least one of conductive carbon black, carbon nanotubes, and acetylene black; and/or the number of the groups of groups,
the solvent comprises at least one of water, absolute ethyl alcohol, n-propanol and isopropanol; and/or the number of the groups of groups,
the hydrophobic polymer comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, polytrifluorostyrene and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer; and/or the number of the groups of groups,
the pore-forming agent comprises at least one of sodium sulfate, ammonium oxalate, ammonium bicarbonate and lithium carbonate.
3. The method for producing a gas diffusion electrode according to claim 1, wherein the mass of the hydrophobic polymer is 40 to 80% of the mass of the carbon material; and/or the number of the groups of groups,
the mass of the pore-forming agent is 10-20% of the mass of the carbon material.
4. The method of making a gas diffusion electrode according to claim 1, wherein the catalyst comprises a manganese dioxide catalyst; and/or the number of the groups of groups,
the carbon material comprises at least one of conductive carbon black, carbon nanotubes and acetylene black; and/or the number of the groups of groups,
the solvent comprises at least one of water, absolute ethyl alcohol, n-propanol and isopropanol; and/or the number of the groups of groups,
the hydrophobic polymer comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, polytrifluorostyrene and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer; and/or the number of the groups of groups,
the pore-forming agent comprises at least one of sodium sulfate, ammonium oxalate, ammonium bicarbonate and lithium carbonate; and/or the number of the groups of groups,
the mass ratio of the catalyst to the carbon material is 1.5-5: 1, a step of; and/or the number of the groups of groups,
the mass of the hydrophobic polymer is 20-40% of the total mass of the carbon material and the catalyst; and/or the number of the groups of groups,
the mass of the pore-forming agent is 10-20% of the total mass of the carbon material and the catalyst.
5. The method of manufacturing a gas diffusion electrode according to claim 1, wherein in step S40:
in the hot pressing treatment, the hot pressing pressure is 1.5-5 MPa, and the hot pressing time is 5-10 min.
6. A metal-air battery comprising a gas diffusion electrode produced by the method of producing a gas diffusion electrode according to any one of claims 1 to 5.
7. A method for preparing oxygen electrochemically is characterized in that water and carbon dioxide are taken as reaction raw materials, and O is generated by electrolysis on an anode 2 At the same time as CO 2 Electrochemical reaction occurs under the action of a cathode catalyst,
wherein the cathode is a gas diffusion electrode produced by the production method of a gas diffusion electrode according to any one of claims 1 to 5.
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| CN1510171A (en) * | 2002-12-26 | 2004-07-07 | Oxygen generation by ion conductive polymer modified electrodes and apparatus thereof | |
| CN1964111A (en) * | 2005-11-10 | 2007-05-16 | 中国科学院大连化学物理研究所 | Electrode and membrane electrode of proton exchange membrane fuel cell, and making method and application |
| CN101702436A (en) * | 2009-10-26 | 2010-05-05 | 新源动力股份有限公司 | Sizing agent for proton exchange membrane fuel cell electrodes and preparation method thereof |
| CN105932300A (en) * | 2016-05-30 | 2016-09-07 | 昆明纳太科技有限公司 | Gas diffusion electrode and preparation method thereof |
| CN109888299A (en) * | 2017-12-06 | 2019-06-14 | 中国科学院大连化学物理研究所 | A kind of metal air battery cathodes and preparation method thereof |
| CN109972162A (en) * | 2019-05-13 | 2019-07-05 | 中国人民解放军军事科学院防化研究院 | A kind of electro-chemistry oxygen-producing method |
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