CN116770362A - Composite diaphragm, preparation method thereof and electrochemical energy device - Google Patents
Composite diaphragm, preparation method thereof and electrochemical energy device Download PDFInfo
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- CN116770362A CN116770362A CN202310747107.1A CN202310747107A CN116770362A CN 116770362 A CN116770362 A CN 116770362A CN 202310747107 A CN202310747107 A CN 202310747107A CN 116770362 A CN116770362 A CN 116770362A
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- 239000002131 composite material Substances 0.000 title claims abstract description 62
- 238000002360 preparation method Methods 0.000 title claims abstract description 21
- 239000004744 fabric Substances 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 17
- 239000011230 binding agent Substances 0.000 claims abstract description 15
- 239000012456 homogeneous solution Substances 0.000 claims abstract description 15
- 239000002002 slurry Substances 0.000 claims abstract description 15
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 13
- 239000000945 filler Substances 0.000 claims abstract description 13
- 239000002243 precursor Substances 0.000 claims abstract description 11
- 208000037516 chromosome inversion disease Diseases 0.000 claims abstract description 9
- 238000005345 coagulation Methods 0.000 claims abstract description 9
- 230000015271 coagulation Effects 0.000 claims abstract description 9
- 239000003960 organic solvent Substances 0.000 claims abstract description 7
- 230000001112 coagulating effect Effects 0.000 claims abstract description 6
- 239000011248 coating agent Substances 0.000 claims abstract description 4
- 238000000576 coating method Methods 0.000 claims abstract description 4
- 239000012528 membrane Substances 0.000 claims description 39
- 229920002492 poly(sulfone) Polymers 0.000 claims description 21
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 19
- 239000011148 porous material Substances 0.000 claims description 19
- 239000002245 particle Substances 0.000 claims description 15
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 14
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 14
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 14
- 239000004734 Polyphenylene sulfide Substances 0.000 claims description 12
- 238000010521 absorption reaction Methods 0.000 claims description 12
- 229920000069 polyphenylene sulfide Polymers 0.000 claims description 12
- 239000003513 alkali Substances 0.000 claims description 11
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 7
- 239000002904 solvent Substances 0.000 claims description 4
- ZFPGARUNNKGOBB-UHFFFAOYSA-N 1-Ethyl-2-pyrrolidinone Chemical compound CCN1CCCC1=O ZFPGARUNNKGOBB-UHFFFAOYSA-N 0.000 claims description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 13
- 230000004888 barrier function Effects 0.000 abstract description 11
- 229920000642 polymer Polymers 0.000 abstract description 11
- 238000007654 immersion Methods 0.000 abstract description 5
- 238000005266 casting Methods 0.000 abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 22
- 238000012360 testing method Methods 0.000 description 18
- 239000003792 electrolyte Substances 0.000 description 15
- 150000002500 ions Chemical class 0.000 description 13
- 239000007789 gas Substances 0.000 description 12
- 238000005868 electrolysis reaction Methods 0.000 description 11
- 239000001257 hydrogen Substances 0.000 description 11
- 229910052739 hydrogen Inorganic materials 0.000 description 11
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 10
- 238000012546 transfer Methods 0.000 description 8
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- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 235000019441 ethanol Nutrition 0.000 description 3
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- 229910052751 metal Inorganic materials 0.000 description 3
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- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
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- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
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- 239000000446 fuel Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
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Abstract
The application relates to a composite diaphragm, a preparation method thereof and an electrochemical energy device, and belongs to the technical field of diaphragm preparation. A method of making a composite separator comprising: s1, dissolving a binder and a pore-forming agent in an organic solvent to obtain a homogeneous solution; s2, adding a filler into the homogeneous solution in the step S1 to obtain precursor slurry; s3, coating the precursor slurry in the step S2 on a support fabric, and then vertically placing the support fabric in a coagulating bath for phase inversion treatment to obtain the composite diaphragm. The preparation method adopts a simple casting method, can be carried out at room temperature, has low cost, is simple and convenient to manufacture, and is easy to scale; in addition, the preparation of the phase-change diaphragm is carried out by adopting a vertical immersion coagulation bath mode, and the surface of the obtained diaphragm does not need to be modified by an additional polymer layer, so that the hydrophilicity of the diaphragm is increased, and the surface resistance is reduced. The diaphragm has excellent gas barrier property and low surface resistance.
Description
Technical Field
The application relates to the technical field of diaphragm preparation, in particular to a composite diaphragm, a preparation method thereof and an electrochemical energy device.
Background
The hydrogen production by water electrolysis has the advantages of high efficiency, cleanliness, mass production and the like, is the only source of green hydrogen, and is therefore recognized as a typical representative of the most feasible and effective clean energy system in the twenty-first century in the future. In a low-temperature electrolytic water system, the alkaline solution water electrolysis has the advantages of low cost, mature technology and the like, and particularly, the alkaline diaphragm electrolytic water hydrogen production is widely applied in industry because the use of noble metal catalyst electrodes can be effectively avoided. The core structure of the alkaline diaphragm hydrogen production by water electrolysis generally adopts a porous diaphragm (such as asbestos, polyphenylene sulfide (PPS) fabric) to separate the anode and cathode, and the interior of the diaphragm is filled with alkaline electrolyte to conduct OH - The ions thereby form a closed circuit.
The composite separator combines the advantages of polymer and porous ceramic,has good mechanical stability, flexibility and wettability. At present, in order to ensure good wettability and mechanical strength of the separator, zrO 2 The mass fraction of (2) is typically as high as 85wt% or more, resulting in high production costs. Moreover, in order to facilitate mass transfer of the electrolyte, the pore size of the separator is generally large, about 150nm, but at the same time, an increase in hydrogen permeability is caused. To overcome the unsafe hidden trouble caused by too high hydrogen permeation, a PSU polymer layer with the thickness of about 1 μm is generally modified on the surface of the diaphragm; although the gas barrier capability of the diaphragm is improved to a certain extent through the strategy, the hydrophobicity of the diaphragm is increased, and the surface resistance of the diaphragm is increased, so that the energy consumption of the whole water electrolysis process is obviously increased, and the popularization of an electrochemical device taking the diaphragm as a key component is severely restricted. Therefore, how to construct a novel hydrophilic/hydrophobic phase by effectively regulating and controlling the internal pore structure of the diaphragm, develop a porous diaphragm with good conductivity, excellent mechanical stability and chemical stability, in particular low hydrogen permeability while realizing high wettability of the diaphragm, and have important realization significance for promoting the development of the high-efficiency alkaline water electrolysis hydrogen production technology.
Disclosure of Invention
The application aims to provide a preparation method of a composite diaphragm, which is used for considering gas barrier property, mechanical property and electric conductivity to a certain extent. The method adopts a simple casting method, can be used for preparation at room temperature, has low cost, is simple and convenient to prepare, and is easy to scale; in addition, the preparation of the phase-change diaphragm is carried out by adopting a vertical immersion coagulation bath mode, and the surface of the obtained diaphragm does not need to be modified by an additional polymer layer, so that the hydrophilicity of the diaphragm is increased, and the surface resistance is reduced.
The second object of the present application is to provide a composite membrane manufactured by the above manufacturing method, which has a smaller pore diameter, a larger bubble point pressure, and excellent hydrogen barrier property; and the surface resistance of the diaphragm is low, and the conductivity is good.
Another object of the present application is to provide an electrochemical energy device comprising the above composite separator.
In order to achieve one of the above purposes, the technical scheme adopted by the application is as follows:
the preparation method of the composite diaphragm comprises the following steps:
s1, dissolving a binder and a pore-forming agent in an organic solvent to obtain a homogeneous solution;
s2, adding a filler into the homogeneous solution in the step S1 to obtain precursor slurry;
s3, coating the precursor slurry in the step S2 on a support fabric, and then vertically placing the support fabric in a coagulating bath for phase inversion treatment to obtain the composite diaphragm.
In order to achieve the second purpose, the technical scheme adopted by the application is as follows:
a composite separator made by the above-described method of manufacture.
In order to achieve the third purpose, the technical scheme adopted by the application is as follows:
an electrochemical energy device comprising a composite separator of any one of the above.
Compared with the prior art, the application has the beneficial effects that at least:
(1) The preparation cost is low: the application reasonably regulates and controls PSU and nano ZrO 2 The mass ratio can effectively reduce the nano ZrO 2 The porous composite membrane for hydrogen production by alkaline water electrolysis can be prepared at room temperature by using a simple casting method at the same time, and polymer and metal salt do not need to be added, so that the cost is low, the preparation is simple and convenient, and the scale is easy.
(2) The gas barrier property is good: the application effectively regulates PVP addition amount and nano ZrO 2 The prepared diaphragm has through finger-shaped porous inside and porous wall, high pore tortuosity and average pore diameter<140nm, high bubble point pressure and good gas barrier property.
(3) The surface resistance is low: according to the application, the PVP molecular weight and PSU addition amount are controlled, and the phase-inversion diaphragm is prepared by adopting a vertical immersion coagulation bath mode, so that the surface of the obtained diaphragm is not required to be modified by an additional polymer layer, the hydrophilicity of the diaphragm is increased, and the surface resistance is reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an SEM image of a composite separator of test example 1 of the present application; wherein, fig. 1a and 1b are surface SEM images of the separator, and fig. 1c is a cross-sectional SEM image of the separator;
FIG. 2 is a graph showing the results of the conductivity and area resistance tests of the composite separator according to test example 2 of the present application;
FIG. 3 is a graph showing the results of the porosity and the alkali absorption of the composite separator according to test example 3 of the present application;
FIG. 4 shows the surface density and surface resistance of the composite separator according to test example 4 of the present application;
FIG. 5 is a graph showing the polarization curve of the composite membrane of test example 5 of the present application at 30wt% KOH, an operating temperature of 60℃and a cell pressure of 2V;
FIG. 6 is a graph showing water contact angle measurements for a commercial Zirfon PERL UTP 500+ separator in a comparative example of the present application;
fig. 7 is a measurement result of water contact angle of the separator prepared in example 5 of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application 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.
The preparation method of the composite diaphragm comprises the following steps:
s1, dissolving a binder and a pore-forming agent in an organic solvent to obtain a homogeneous solution;
s2, adding a filler into the homogeneous solution in the step S1 to obtain precursor slurry;
s3, coating the precursor slurry in the step S2 on a support fabric, and then vertically placing the support fabric in a coagulating bath for phase inversion treatment to obtain the composite diaphragm.
The preparation method provided by the application can be used for preparation at room temperature, is simple to operate, is easy to scale, does not need additional polymer or metal salt, and is low in cost; in addition, the precursor slurry is vertically put into the coagulation bath, so that the two sides of the diaphragm are subjected to the phase separation process at the same time, thereby being beneficial to forming finger-shaped through holes and improving the permeation flux of electrolyte; in the preparation method, other polymers are not added to modify the surface of the diaphragm, and hydrophilic filler particles are fully exposed on the surface, so that the hydrophilicity of the prepared diaphragm is increased, and the surface resistance is reduced.
In some embodiments, the mass ratio of binder to filler is 1 (1-4); and/or the mass ratio of the pore-forming agent to the binder is 1 (2-8); and/or the particle diameter of the filler is any one of 40nm, 100nm and 200nm. By reasonably controlling PSU (binder) and nano ZrO 2 The mass ratio can effectively reduce the nano ZrO 2 The porous composite membrane for hydrogen production by alkaline water electrolysis can be prepared at room temperature by using a simple tape casting method, and polymer and metal salt are not required to be additionally arranged, so that the cost is low; by effectively regulating and controlling the addition amount of a pore-forming agent (PVP) and nano ZrO 2 The particle size scale, the prepared diaphragm has through finger-shaped porous inside, presents a hydrophilic/hydrophobic phase separation microstructure, can effectively reduce the mass transfer resistance of electrolyte and improve OH - Conductivity, average pore diameter<140nm, high bubble point pressure and excellent gas barrier property.
In some embodiments, the weight average molecular weight of the binder is 22000-80000; and/or the weight average molecular weight of the pore-forming agent is 10000-40000. The PVP molecular weight and PSU addition amount are controlled, and the phase-inversion diaphragm is prepared by adopting a vertical immersion coagulation bath mode, so that the surface of the obtained diaphragm is not required to be modified by an additional polymer layer, and hydrophilic filler particles are fully exposed on the surface, thereby increasing the hydrophilicity of the diaphragm and reducing the surface resistance.
In some embodimentsWherein the fabric is polyphenylene sulfide fabric containing a support body, and the mesh number of the fabric is 40-60. The support fabric PPS provides a certain mechanical strength, the PPS net strength is about 70MPa, thus reducing nano ZrO 2 The wettability and mechanical properties of the composite membrane are not affected at the same time when the amount of the composite membrane is less than or equal to 80 percent.
In some embodiments, the binder is polysulfone; and/or the pore-forming agent is polyvinylpyrrolidone; and/or the filler is nano zirconium dioxide; and/or the organic solvent comprises any one of N-methyl pyrrolidone and N-ethyl pyrrolidone.
In some embodiments, the organic solvent is N-methylpyrrolidone.
In some embodiments, the mass fraction of binder in the homogeneous solution is 15-20%; and/or the mass fraction of the pore-forming agent in the homogeneous solution is 5-15%.
In some embodiments, step S1 is performed under stirring conditions comprising: stirring at a speed of 150-300r/min; stirring for 6-12h;
and/or, step S2 is carried out under stirring conditions, wherein the stirring conditions comprise: stirring at a speed of 150-300r/min; the stirring time is 6-12h.
In some embodiments, the solvent used in the coagulation bath is an aqueous ethanol solution, preferably any one of absolute ethanol, 95% aqueous ethanol solution, and 25-75% aqueous ethanol solution;
and/or the phase inversion treatment time is 30-120min.
In some embodiments, the time of the phase inversion treatment is 30 minutes.
A composite separator made by the above-described method of manufacture.
The membrane has a plurality of finger-shaped holes in the inside, presents a hydrophilic/hydrophobic phase separation microstructure, can effectively reduce the mass transfer resistance of electrolyte and improve OH - Conductivity capability; the surface of the diaphragm is not provided with a dense polymer layer, hydrophilic filler particles are fully exposed on the surface, the diaphragm has good wettability, the support fabric PPS provides certain mechanical strength, and the PPS net has the strength of about 70Mpa, so that the nano ZrO is reduced 2 The wettability and mechanical properties of the composite membrane are not affected at the same time when the amount of the composite membrane is less than or equal to 80 percent.
In some embodiments, the average pore size of the finger pores is 130-140nm;
and/or the bubble point pressure of the composite membrane is 0.4-0.5Mpa;
and/or the surface resistance of the composite membrane is 0.27-0.30 omega cm 2 ；
And/or the porosity of the composite membrane is 60+/-10%;
and/or the alkali absorption rate of the composite membrane is 60+/-5%;
and/or the composite membrane has a conductivity of 160-200mS/cm.
The size of the pore size affects the ion transport rate of the electrolyte in the separator. Smaller pore sizes may limit the diffusion and migration of ions, resulting in a reduced ion transport rate of the electrolyte, thereby affecting the conductive properties of the separator. Conversely, a larger pore size may provide more channels and space, facilitating rapid transport of ions, thereby improving the conductive properties of the separator. The average pore diameter of the finger-shaped porous membrane is less than 140nm, the conductivity is more than 160mS/cm, and the membrane provided by the application has excellent conductivity, and the smaller pore diameter can reduce the permeation of gas molecules through the membrane, so that the gas barrier property of the membrane is improved.
Porosity refers to the ratio of the volume of pores in the separator to the total volume. Higher porosity means more void space in the separator, facilitating electrolyte permeation and ion transport. Thus, higher porosity generally increases the conductive properties of the separator, facilitating ion transport in the electrolyte, and thus reduces resistance.
The alkali absorption rate refers to the alkaline ion (such as hydroxide ion OH) in the alkaline electrolyte - ) Is used for the adsorption capacity of the catalyst. Higher alkali absorption means that the membrane is better able to absorb and store alkaline ions, thus helping to increase the concentration and transport rate of ions. Thus, higher alkali absorption generally increases the conductive properties of the separator, facilitating ion transport in the electrolyte.
The sheet resistance of the separator is important to the conductivity of the separatorInfluence. The plane resistance is a resistance value per unit area of the diaphragm, and represents resistance to current passing through the diaphragm. The lower the sheet resistance, the smaller the resistance per unit area, and the less resistance is encountered by the current through the diaphragm. Thus, a lower sheet resistance means that the diaphragm has better electrical conductivity and current can more easily pass through the diaphragm, thereby reducing the overall resistance. In the application, the surface resistance of the composite diaphragm is less than 0.30 omega cm 2 The surface resistance is lower, the conductivity and the current transmission efficiency can be improved, and the energy loss is reduced.
The presence of the finger holes provides more channels and paths for ions (e.g., OH - ) Can be more easily transported and spread. By forming the finger hole, the following effect can be improved: 1) Mass transfer resistance decreases: the finger holes provide additional mass transfer channels, reducing the diffusion path length of the electrolyte in the separator, thereby reducing mass transfer resistance; this allows ions to pass through the membrane faster, improving ion conductivity. 2) OH (OH) - Conductivity is improved: the finger holes can provide more paths to promote alkaline ions (OH - ) Conduction in the membrane; due to OH - The ions have important conduction function in alkaline water electrolysis, and the existence of finger holes can increase OH - Diffusion and conduction rate of ions, thereby improving OH - Conductivity capability; it is helpful to reduce mass transfer resistance of electrolyte and improve ion conductivity, thereby improving conductivity and electrolysis efficiency of the diaphragm.
Bubble point pressure refers to the pressure at which the gas in the membrane begins to permeate at a certain temperature. Higher bubble point pressures indicate that the membrane has better gas barrier properties and is more effective in preventing permeation of gases.
An electrochemical energy device comprising the composite separator described above.
As an example, the electrochemical energy devices described above include, but are not limited to, alkaline water baths, alkaline zinc air cells, alkaline direct methanol fuel cells.
The features and capabilities of the present application are described in further detail below in connection with the examples.
Example 1
The embodiment provides a composite diaphragm, which is prepared by the following steps:
step 1: polyvinylpyrrolidone (PVP) and Polysulphone (PSU) with molecular weight of 80000 in a mass ratio of 1:4 were weighed into 20mL solvent N-methylpyrrolidone (NMP), and mechanically stirred at 300rpm for 12h at normal temperature to form a homogeneous solution.
Step 2: taking a certain amount of nano ZrO with grain diameter of 100nm 2 Adding the powder into the homogeneous solution obtained in the step 1, and controlling PSU and nano ZrO 2 The mass ratio is 1:4, and the mixture is mechanically stirred for 12 hours at normal temperature at 150rpm and then is kept stand for defoaming to form milky precursor slurry.
Step 3: the slurry was poured onto a home-made slot coater, the slot width was controlled to 500 μm, a 50 mesh PPS fabric was passed through the slot and uniformly coated with a layer of the slurry, after which it was placed vertically in an absolute ethyl alcohol coagulation bath for 30min.
Step 4: and taking the PPS net out of the coagulating bath, and drying under natural conditions to obtain the porous composite diaphragm.
Example 2
The embodiment provides a composite diaphragm, which is prepared by the following steps:
step 1: PVP and PSU (molecular weight of 80000) in a mass ratio of 1:2 were weighed and dissolved in 20mL of NMP solvent, and mechanically stirred at 300rpm for 12h at room temperature to form a homogeneous solution.
Step 2: weighing a certain amount of nano ZrO with particle size of 100nm 2 Adding the powder into the homogeneous solution obtained in the step 1, and controlling PSU and nano ZrO 2 The mass ratio is 1:1, and the mixture is mechanically stirred for 12 hours at the normal temperature at 150rpm and then is kept stand for defoaming to form milky precursor slurry.
Step 3: the slurry was poured onto a home-made slot coater with a slot width of 500 μm, a layer of slurry was uniformly applied through the slot using a 60 mesh PPS fabric, and then vertically placed in an absolute ethyl alcohol coagulation bath for 30 minutes.
Step 4: and taking the PPS net out of the coagulating bath, and drying under natural conditions to obtain the porous composite diaphragm.
Example 3
This embodiment is substantially the same as embodiment 2 except that: PSU and nano ZrO 2 The mass ratio is 1:2.
Example 4
This embodiment is substantially the same as embodiment 2 except that: PSU and nano ZrO 2 The mass ratio is 1:3.
Example 5
This embodiment is substantially the same as embodiment 2 except that: PSU and nano ZrO 2 The mass ratio is 1:4.
Example 6
This embodiment is substantially the same as embodiment 5 except that: the mass ratio of PVP to PSU was 1:4.
Example 7
This embodiment is substantially the same as embodiment 5 except that: the mass ratio of PVP to PSU was 1:8.
Example 8
This embodiment is substantially the same as embodiment 5 except that: nano ZrO 2 The particle size of (2) was 40nm.
Example 9
This embodiment is substantially the same as embodiment 5 except that: nano ZrO 2 The particle size of (2) was 200nm.
Example 10
This embodiment is substantially the same as embodiment 2 except that: PSU and nano ZrO 2 The mass ratio is 2:1.
Example 11
This embodiment is substantially the same as embodiment 2 except that: PSU and nano ZrO 2 The mass ratio is 1:7.
Example 12
This embodiment is substantially the same as embodiment 5 except that: the mass ratio of PVP to PSU was 1:1.
Example 13
This embodiment is substantially the same as embodiment 5 except that: the mass ratio of PVP to PSU was 1:10.
Example 14
This embodiment is substantially the same as embodiment 5 except that: nano ZrO 2 The particle size of (2) was 20nm.
Example 15
This embodiment is substantially the same as embodiment 5 except that: nano ZrO 2 The particle size of (2) was 400nm.
Test example 1
This test example was characterized by Scanning Electron Microscopy (SEM) of the microscopic morphology of the surface and cross section of the composite separator prepared in example 1 of the present application, and the results are shown in fig. 1.
In fig. 1, fig. 1a and 1b show the surface of the membrane, and fig. 1c shows an enlarged cross-section of the membrane. As can be seen from FIGS. 1a and 1b, the composite separator has a surface ZrO 2 The particle size distribution is uniform, and the particle size distribution is in a layered porous structure; as can be seen from FIG. 1c, the composite membrane has finger-shaped holes formed therein, which can effectively reduce mass transfer resistance of electrolyte and improve OH - Conductivity capability.
Test example 2
The composite diaphragms prepared in examples 2-5 are respectively cut into squares with the size of 2cm x 2cm, then the squares are placed in a PTFE conductivity cell, the conductivity is tested by using an alternating current impedance method by using a Chen Hua electrochemical workstation CH-760E under saturated steam at 25 ℃, and the diaphragm surface resistance is obtained through conversion, and the result is shown in figure 2.
As can be seen from FIG. 2, with nano ZrO 2 The proportion increases and the conductivity of the diaphragm increases.
Test example 3
The composite diaphragms prepared in examples 5-7 are adopted for alkali absorption rate and porosity test, the composite diaphragms prepared in examples 6-8 are respectively cut into squares with the size of 2cm x 2cm, dry weight is measured, and then the squares are respectively placed in a beaker filled with 6M KOH and deionized water for 12 hours of immersion; and then the mass difference of the dry film and the wet film before and after alkali absorption and water absorption is measured, and the alkali absorption rate and the porosity of the diaphragm material are calculated, and the result is shown in figure 3.
As can be seen from fig. 3, as the PVP content increases, both the porosity and the alkali absorption rate of the separator increase significantly, thereby contributing to an improvement in the conductive performance of the separator.
Test example 4
The composite diaphragms prepared in examples 5 and 8-9 were cut into squares of 2cm x 2cm in size, and the dry weight was measured to calculate the areal density of the diaphragm. The sheet resistance of the separator was measured in the same manner as in test example 2, and the results are shown in fig. 4.
As can be seen from FIG. 4, with nano ZrO 2 The increase in particle size, the areal density of the separator decreases and has the lowest areal resistance when the particle size is 100 nm.
Test example 5
The composite separator prepared in example 5 was used for the electrolytic water performance test and the gas barrier performance test.
(1) The alkaline water electrolysis experiment was carried out in a double-chamber zero-pitch electrolyzer from the scientific materials station under the model LSCF-261000 with an effective electrode area of 15cm 2 The diaphragm is replaced by the product. 30% KOH was used as electrolyte at 60 ℃. The direct current power supply is used for supplying power, the groove pressure ranges from 1.5V to 2.1V, the step size is 0.05V, and corresponding current is recorded. As shown in FIG. 5, the polarization curve of the alkaline water electrolysis cell of the membrane is shown in FIG. 5, and the porous composite membrane surface shows low surface resistance which is less than 0.27 omega cm 2 Is significantly better than Zirfon PERL membrane (about 0.30 Ω cm) 2 ). In addition, the operating temperature is controlled to be 60 ℃, and the current density exceeds 800mA/cm under the cell pressure of 2V in 30% KOH electrolyte solution 2 Meets the commercial application conditions.
(2) The bubble point pressure and the maximum pore diameter of the obtained porous composite membrane were measured with reference to GB/T26204-2010 "test for bubble point air Performance test of liquid phase Filter Material", and the results are shown in Table 1.
As can be seen from Table 1, the bubble point pressure of the prepared composite membrane is 0.414Mpa, which is significantly better than that of a Zirfon PERL membrane (about 0.3 Mpa), the average pore diameter is about 136nm, and the composite membrane has good gas barrier property.
TABLE 1
Test example 6
In this test example, the average pore diameter, the surface resistance, the porosity, the alkali absorption, the conductivity and the contact angle of the separator were measured for the separators of examples 1 to 15 by the test methods of test examples 2 to 5, and the measurement results are shown in Table 2.
TABLE 2
Comparative example
The water contact angles of commercial Zirfon PERL utp500+ separators (available from the company of the tendril-russian technology) and porous composite separators obtained in example 5 were measured with reference to GB/T30693-2014, measurement of who contact angle with plastic films, respectively, and the results are shown in fig. 6 and 7, respectively.
FIG. 6 is a water contact angle measurement of a commercial Zirfon PERL UTP500+ separator with a water contact angle of about 92; fig. 7 is a measurement of the water contact angle of the separator of example 5, which is about 58 °. Therefore, the product has better hydrophilicity and wettability by reasonably regulating and controlling the pore structure and the surface morphology of the diaphragm.
The embodiments described above are some, but not all embodiments of the application. The detailed description of the embodiments of the application is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Claims (10)
1. The preparation method of the composite diaphragm is characterized by comprising the following steps of:
s1, dissolving a binder and a pore-forming agent in an organic solvent to obtain a homogeneous solution;
s2, adding a filler into the homogeneous solution in the step S1 to obtain precursor slurry;
s3, coating the precursor slurry in the step S2 on a support fabric, and then vertically placing the support fabric in a coagulating bath for phase inversion treatment to obtain the composite diaphragm.
2. The preparation method according to claim 1, wherein the mass ratio of the binder to the filler is 1 (1-4); and/or the mass ratio of the pore-forming agent to the binder is 1 (2-8); and/or the particle diameter of the filler is any one of 40nm, 100nm and 200nm.
3. The method of claim 1, wherein the binder has a weight average molecular weight of 22000-80000; and/or the weight average molecular weight of the pore-forming agent is 10000-40000.
4. A method of producing according to any one of claims 1 to 3, wherein the fabric is a polyphenylene sulfide fabric containing a support, and the mesh number of the fabric is 40 to 60.
5. A method of preparation according to any one of claims 1 to 3, wherein the binder is polysulphone;
and/or, the pore-forming agent is polyvinylpyrrolidone;
and/or, the filler is nano zirconium dioxide;
and/or the organic solvent comprises any one of N-methyl pyrrolidone and N-ethyl pyrrolidone, preferably N-methyl pyrrolidone.
6. A method according to any one of claims 1 to 3, wherein the mass fraction of the binder in the homogeneous solution is 15-20%; and/or the mass fraction of the pore-forming agent in the homogeneous phase solution is 5-15%.
7. A method according to any one of claims 1 to 3, wherein step S1 is performed under stirring conditions comprising: stirring at a speed of 150-300r/min; stirring for 6-12h;
and/or, the step S2 is performed under stirring conditions, wherein the stirring conditions comprise: stirring at a speed of 150-300r/min; the stirring time is 6-12h.
8. A method according to any one of claims 1 to 3, wherein the solvent used in the coagulation bath is an aqueous ethanol solution, preferably any one of absolute ethanol, 95% aqueous ethanol solution and 25-75% aqueous ethanol solution;
and/or the time of the phase inversion treatment is 30-120min, preferably 30min.
9. A composite separator made by the method of any one of claims 1-8;
preferably, the composite membrane is provided with a plurality of through finger holes, and the average pore diameter of the finger holes is 130-140nm;
and/or the bubble point pressure of the composite membrane is 0.4-0.5Mpa;
and/or the surface resistance of the composite membrane is 0.27-0.30 omega cm 2 ；
And/or, the porosity of the composite membrane is 60+/-10%;
and/or, the alkali absorption rate of the composite membrane is 60+/-5%;
and/or the conductivity of the composite membrane is 160-200mS/cm.
10. An electrochemical energy device comprising the composite separator of claim 9.
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| CN117305904A (en) * | 2023-10-11 | 2023-12-29 | 北京元泰能材科技有限公司 | Composite slurry, porous diaphragm, preparation method and application thereof |
| CN117305904B (en) * | 2023-10-11 | 2024-04-23 | 北京元泰能材科技有限公司 | Composite slurry, porous diaphragm, preparation method and application thereof |
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