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WO2016002227A1 - Membrane de séparation de pile à combustible liquide et ensemble membrane-électrode pourvu de celle-ci - Google Patents

Membrane de séparation de pile à combustible liquide et ensemble membrane-électrode pourvu de celle-ci Download PDF

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Publication number
WO2016002227A1
WO2016002227A1 PCT/JP2015/003348 JP2015003348W WO2016002227A1 WO 2016002227 A1 WO2016002227 A1 WO 2016002227A1 JP 2015003348 W JP2015003348 W JP 2015003348W WO 2016002227 A1 WO2016002227 A1 WO 2016002227A1
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WIPO (PCT)
Prior art keywords
diaphragm
liquid fuel
water
fuel cell
weight
Prior art date
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Application number
PCT/JP2015/003348
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English (en)
Japanese (ja)
Inventor
康壮 松田
武史 仲野
西井　弘行
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Nitto Denko Corp
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Nitto Denko Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from JP2014137789A external-priority patent/JP2016015284A/ja
Priority claimed from JP2014137792A external-priority patent/JP2016015287A/ja
Priority claimed from JP2014137790A external-priority patent/JP2016015285A/ja
Priority claimed from JP2014137791A external-priority patent/JP2016015286A/ja
Application filed by Nitto Denko Corp filed Critical Nitto Denko Corp
Publication of WO2016002227A1 publication Critical patent/WO2016002227A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/08—Fuel cells with aqueous electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/22—Fuel cells in which the fuel is based on materials comprising carbon or oxygen or hydrogen and other elements; Fuel cells in which the fuel is based on materials comprising only elements other than carbon, oxygen or hydrogen
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a diaphragm for a liquid fuel cell and a membrane-electrode assembly including the same.
  • the polymer electrolyte fuel cell has advantages such as being able to operate at a low temperature as a fuel cell and having a high output density, and is expected to spread in the future.
  • the PEFC includes a diaphragm between the anode and the cathode, and a polymer electrolyte membrane having ion conductivity is used as the diaphragm. As this diaphragm, a cation exchange membrane has been used.
  • PEFCs using an anion exchange membrane that can generate electricity without using platinum as a catalyst have been reported (for example, Patent Document 1 and Patent Document 2).
  • the liquid fuel cell diaphragm is used by impregnating the diaphragm with an aqueous solution. Therefore, the diaphragm for liquid fuel cells is required to have a small area expansion before and after impregnation with the aqueous solution in order to prevent deformation when the aqueous solution is impregnated.
  • the pH of the aqueous solution contained in the diaphragm becomes acidic or alkaline.
  • a liquid fuel cell hereinafter referred to as an alkaline liquid fuel cell
  • the pH of the aqueous solution becomes alkaline. Accordingly, the diaphragm is required to have good chemical durability against the pH of the aqueous solution.
  • the present invention relates to a diaphragm for a liquid fuel cell, and an object thereof is to provide a diaphragm for a liquid fuel cell having a small area swelling rate and good chemical durability.
  • ion-exchange membranes are used as diaphragms for fuel cells, and these membranes are non-porous membranes.
  • a polymer porous membrane having a hydrophilic functional group by using a polymer porous membrane having a hydrophilic functional group, a membrane for a liquid fuel cell having a small area swelling rate and good chemical durability.
  • the present invention A diaphragm for a liquid fuel cell, A polymer porous membrane, Graft chains introduced into the polymer porous membrane; With The graft chain includes a hydrophilic functional group; A diaphragm for a liquid fuel cell is provided.
  • the present invention provides: There is provided a membrane-electrode assembly (MEA) comprising a diaphragm for a liquid fuel cell of the present invention.
  • MEA membrane-electrode assembly
  • the present invention it is possible to provide a diaphragm for a liquid fuel cell having a small area swelling rate and high chemical durability. According to the present invention, an MEA that takes advantage of the characteristics of the diaphragm can be obtained.
  • FIG. 3 is a longitudinal sectional view of a schematic evaluation cell on the III-III plane of FIG. 2. It is a front view which shows typically the cell for evaluation used for a water transmission rate test or a pressure resistance test.
  • liquid fuel cell diaphragm of the present invention is not limited to this and can be used for an acid liquid fuel cell. .
  • the MEA of this embodiment is suitable for use in a liquid fuel cell.
  • This liquid fuel cell is not particularly limited to a portion other than the MEA, and a known member can be applied.
  • the liquid fuel cell described below is an alkaline liquid fuel cell equipped with the MEA of the present embodiment, and liquid fuel is supplied to the anode side and oxidant is supplied to the cathode side.
  • the oxidizing agent is air, for example.
  • the liquid fuel is a fuel dissolved in water and dissolves an electrolyte.
  • the fuel is not particularly limited as long as it can be dissolved in water. Examples thereof include lower alcohols such as methanol and ethanol, amines such as hydrazine (hydrate) and ammonia, sodium borohydride, and the like. Hydrazine (hydrate) is preferable because it is high and does not generate CO 2 on the principle of power generation.
  • the amount of fuel supplied can be controlled by the concentration of fuel in the liquid fuel and the supply speed (flow rate).
  • the amount of fuel required varies depending on the amount of current to be extracted. Therefore, it is preferable to control the amount of fuel supplied to the anode side in accordance with the amount of current to be extracted. If an excessive amount of fuel is supplied relative to the amount of current to be extracted, the amount of fuel permeation may increase.
  • the permeated fuel is present on the cathode, more specifically, on the cathode catalyst, the oxidant and the fuel may directly react on the cathode catalyst to cause a side reaction, thereby reducing the power generation efficiency of the fuel cell.
  • a fuel providing system capable of controlling the supply amount of liquid fuel may be used.
  • the electrolyte is not particularly limited as long as it is an electrolyte that can be dissolved in water or liquid fuel and functions as an ionic conductor in the liquid fuel cell reaction.
  • an anion functions as an ionic conductor, so use an electrolyte that can dissociate hydroxide ions (OH - ions) such as potassium hydroxide, sodium hydroxide, and calcium hydroxide.
  • hydroxide ions OH - ions
  • potassium hydroxide which is a reaction product with carbon dioxide, is easily dissolved in water and hardly precipitated
  • potassium hydroxide is particularly preferable as the electrolyte.
  • other inorganic salts, ionic liquids, etc. that can be dissolved in water and can supply ions when dissolved in water can also be used as the electrolyte.
  • the concentration of the electrolyte in the liquid fuel is not particularly limited, but is, for example, 0.5 to 40%, particularly 1 to 20% on a weight basis.
  • the feature of the present embodiment is that the electrolyte bears ionic conductivity, and this point is different from the generally used liquid fuel cell.
  • an anion exchange membrane is used for the diaphragm, and the anion exchange group of the anion exchange membrane bears ion conductivity. Therefore, when the anion exchange group is deteriorated, the performance of the liquid fuel cell is lowered.
  • the MEA of the present embodiment that can conduct ions even without an anion exchange group, it is not necessary to consider the deterioration of the anion exchange group.
  • the diaphragm for a liquid fuel cell provided in the MEA of this embodiment has a hydrophilic functional group and can hold water in the diaphragm. Since the liquid fuel is supplied from the anode side to the MEA of this embodiment, water contained in the liquid fuel permeates the diaphragm to the cathode side and is used for the reaction in the cathode catalyst. Therefore, use of the MEA of this embodiment makes it possible to omit auxiliary equipment for humidification, which is advantageous in reducing the size of the liquid fuel cell and improving the power generation capacity per unit volume.
  • the above liquid fuel cell It is also possible to provide auxiliary equipment for processing the gas discharged from the outlet.
  • a catalyst layer is disposed on the surface of the diaphragm of the present invention.
  • the diaphragm and the catalyst layer are typically integrated through a processing step such as spray application of catalyst ink.
  • the catalyst layer includes an anode catalyst layer and a cathode catalyst layer.
  • FIG. 1 shows an example of the MEA of this embodiment.
  • the MEA shown in FIG. 1 includes a diaphragm 2, an anode catalyst layer 3, and a cathode catalyst layer 4.
  • the anode catalyst layer 3 is on one main surface of the diaphragm
  • the cathode catalyst layer 4 is on the other main surface of the diaphragm 2, respectively. Has been placed.
  • the method for forming the MEA is not particularly limited as long as the effects of the present invention are not impaired.
  • the CCM Catalyst Coated on Membrane
  • the CCS Catalyst Coated on Substrate
  • a catalyst layer provided in a known MEA used in an alkaline liquid fuel cell can be used. Unlike an acid fuel cell, the catalyst does not necessarily need to be a noble metal such as platinum. For example, a base metal such as nickel, cobalt, or iron can be used.
  • the structure of the catalyst layer, such as the specific catalyst contained, may be different or the same on the anode side (anode catalyst layer) and cathode side (cathode catalyst layer) of the MEA.
  • the cathode catalyst layer it is desirable to select a catalyst that selectively promotes the oxidation-reduction reaction from the viewpoint of suppressing a reaction with the permeated fuel to prevent a decrease in power generation efficiency and preventing member deterioration due to a side reaction.
  • the MEA of the present embodiment can have any member other than the diaphragm and the catalyst layer as long as the effects of the present invention are not impaired.
  • the diaphragm for a liquid fuel cell includes a polymer porous membrane and a graft chain introduced into the polymer porous membrane, and the graft chain includes a hydrophilic functional group.
  • the liquid fuel cell membrane preferably has a thickness in the range of 5 ⁇ m to 130 ⁇ m, and more preferably in the range of 10 ⁇ m to 70 ⁇ m. If the film thickness becomes too thin, the film strength may decrease, and the film may be damaged or defects such as pinholes may occur, which may prevent the pressure of the oxidizing agent from being maintained. Further, the amount of fuel permeation and the amount of water permeation (water permeation amount) may increase. If the film thickness becomes too thick, the resistance (film resistance) as a film within the diaphragm may increase, and the water permeability may decrease. When the amount of water permeation decreases, water required for the reaction in the cathode catalyst may be insufficient, and power generation efficiency may be reduced.
  • the water content of the diaphragm of the present embodiment is preferably 30% or more, preferably 40% to 100%, more preferably 50% to 80% with respect to the weight of the diaphragm at the time of drying.
  • the hydrophilic functional group of the diaphragm retains water, so that the pores of the porous film are compensated.
  • the pressure of an oxidizing agent such as Moreover, since the water retained in the diaphragm permeates to the cathode side, water can be efficiently supplied to the cathode catalyst, which can contribute to the improvement of the power generation efficiency of the battery. If the moisture content is too small, the pores of the porous membrane may not be sufficiently filled and may not be able to withstand the pressure of an oxidizing agent such as air. If the water content is too high, the pressure resistance of the diaphragm against a gas such as air may be reduced, and the pressure of the oxidant may not be maintained.
  • the diaphragm at the time of drying is a diaphragm in a state in which dimensional change does not occur after being left in an atmosphere of 23 ° C. and 50% relative humidity for 24 hours or more. It is a diaphragm in a state of being swollen by being immersed in water at 2 ° C. for 2 hours.
  • the moisture content can be measured using the following method.
  • a sample cut into a rectangular shape having a length of 30 mm and a width of 20 mm is left in an atmosphere at 23 ° C. and a relative humidity of 50% for 24 hours or more, and the weight of the sample in which no dimensional change occurs is measured (weight before water inclusion).
  • a weight is measured (weight after water-containing).
  • the weight after moisture is measured after wiping off excess water adhering to the sample surface with a filter paper or the like.
  • the moisture content is a ratio calculated based on the following formula.
  • Moisture content (%) ((weight after hydration) ⁇ (weight before hydration)) ⁇ 100 / (weight before hydration)
  • the diaphragm of this embodiment has a reduced area swelling rate and good dimensional stability.
  • the area swelling ratio is preferably less than 20%, more preferably 15% or less, further preferably 0% to 10%, and particularly preferably 0% to 5%. If the area swelling rate becomes too large, the diaphragm may be deformed, leading to deterioration of the diaphragm. Moreover, when the area swelling rate becomes too large, in the liquid fuel cell provided with the diaphragm of the present embodiment, the bondability between the diaphragm and the electrode during operation of the fuel cell may be inferior.
  • the area swelling rate can be measured using the following method.
  • a sample cut into a rectangular shape having a length of 30 mm and a width of 20 mm is left in an atmosphere of 23 ° C. and 50% relative humidity for 24 hours or more, and the area of the sample in which no dimensional change occurs is measured (area before water inclusion). Then, after immersing this sample in 30 degreeC pure water for 2 hours, an area is measured (area after water inclusion).
  • the area swelling rate is a ratio calculated based on the following formula.
  • Area swelling rate (%) ((area after water inclusion) ⁇ (area before water inclusion)) ⁇ 100 / (area before water inclusion)
  • a liquid fuel cell (alkaline liquid fuel cell) utilizing the movement of anions
  • fuel is supplied to the anode side and an oxidant such as air is supplied to the cathode side.
  • an oxidant such as air
  • this water is supplied by being humidified from the outside using an auxiliary device such as a humidifier.
  • auxiliary equipment it is desirable to omit auxiliary equipment as much as possible from the viewpoint of miniaturization of the fuel cell and improvement of power generation capacity per unit volume.
  • a liquid fuel cell Like a fuel cell using gas as a fuel, a liquid fuel cell includes a membrane-electrode assembly (MEA) in which a diaphragm and a catalyst layer are integrated. From the viewpoint of the stable power generation efficiency of the liquid fuel cell, it is required that separation at the interface between the diaphragm and the catalyst layer hardly occurs. Since deformation of the diaphragm at the interface with the catalyst layer can contribute to this separation, the diaphragm is required to have good dimensional stability.
  • MEA membrane-electrode assembly
  • the present inventors examined a diaphragm that can supply water to the cathode side satisfactorily. As a result, it was found that water can be stably supplied to the cathode side by using a diaphragm having a moisture content of a specific value or more.
  • the diaphragm in order to suppress the separation between the diaphragm and the catalyst layer in the MEA, the diaphragm has a good dimensional stability, particularly, has a good dimensional stability at the interface between the diaphragm and the catalyst layer (area direction of the diaphragm). It is preferable. As a result of studies by the present inventors, it has been found that the separation of the membrane and the catalyst layer in the MEA can be suppressed by using a membrane having an area swelling ratio in a specific range.
  • the ratio of the weight difference between the weight of the diaphragm when wet and the weight of the diaphragm when dried to the weight of the diaphragm when dried is 30% by weight or more, The ratio of the area difference between the area of the diaphragm when wet and the area of the diaphragm when dried to the area of the diaphragm when dried is less than 20%.
  • a diaphragm for a liquid fuel cell is provided.
  • the liquid fuel cell is preferably in alkaline form.
  • the present invention can provide a diaphragm for a liquid fuel cell that can contribute to improving the characteristics of the liquid fuel cell.
  • a dry diaphragm swells when it absorbs water. Therefore, it has been difficult to obtain a diaphragm having both a good moisture content and a good dimensional stability (suppressed swelling rate). On the other hand, the moisture content of the diaphragm is good, and swelling in the area direction of the diaphragm is suppressed.
  • This diaphragm is preferably a porous film having a hydrophilic functional group.
  • the diaphragm preferably comprises a porous membrane and a hydrophilic functional group present on the porous membrane.
  • the porous film include a porous film made of an inorganic base material and a porous film made of a polymer base material.
  • the water transmission rate in the cross-sectional direction is preferably 40 mol / h ⁇ g or more, more preferably 40 to 120 mol / h ⁇ g, and more preferably 50 to 110 mol / h ⁇ g. Further preferred. If the water permeation rate in the cross-sectional direction of the diaphragm becomes too small, water necessary for the reaction on the cathode catalyst may not permeate sufficiently, and the reaction efficiency in the cathode catalyst may be reduced.
  • the diaphragm of the present embodiment in which the water permeation speed in the cross-sectional direction is in a specific range, water that has permeated the diaphragm from the anode side to the cathode side can be appropriately supplied to the cathode catalyst.
  • the reaction efficiency on the cathode catalyst can be improved, and the power generation efficiency of the battery can be further improved.
  • the water transmission rate in the cross-sectional direction of the diaphragm can be measured by the following method using the evaluation cell 100 shown in FIGS.
  • a diaphragm 2 having a first main surface and a second main surface opposite to the first main surface is prepared, and a diaphragm is formed by a pair of gaskets 11 and 21 having square openings 11a and 21a each having a side length of 2 cm. 2 is pinched.
  • a pair of separators 12 and 22 with serpentine-structured flow channels 12a and 22a, a pair of current collector plates 13 and 23, and a pair of end plates 14 and 24 are arranged in this order to form the diaphragm 2 Hold it.
  • Each member is fastened using a fixing part (not shown) such as a bolt so that air and water do not leak from each contact surface of the member, and the evaluation cell 100 is formed.
  • the evaluation cell 100 has flow paths 18, 19, 28, and 29.
  • the channels 18 and 19 are channels for supplying and discharging water, respectively, and the channels 28 and 29 are channels for supplying and discharging dry air, respectively.
  • Each flow path 18, 19, 28, 29 has an opening in the end plate.
  • the flow paths 18 and 19 penetrate the end plate 14, the current collector plate 13, and the separator 12, and are connected to the flow path 12a.
  • the evaluation cell 100 is installed so that the first main surface and the second main surface of the diaphragm 2 are along the vertical direction, and supply of water and dry air to the evaluation cell 100 in this state is started. 2 ml of water per minute is supplied to the first main surface via a pipe 38 connected to the flow path 18, and 500 ml of dry air per minute is supplied to the second main face via a pipe 48 connected to the flow path 28. Supply. By continuing to supply water as described above, the inside of the first main surface side of the cell 100 is filled with the supplied water, and the first main surface of the diaphragm 2 is always in contact with water.
  • the evaluation cell 100 is heated using the rubber heaters 15 and 25 provided on the end plates 14 and 24 so that the temperature of the evaluation cell 100 becomes 80 ° C.
  • Water and dry air are continuously supplied as described above, and water discharged from the pipe 39 connected to the flow path 19 is collected for 30 minutes while maintaining the temperature of the evaluation cell 100 at 80 ° C. (W2).
  • W1 is the weight of water supplied to the evaluation cell 100 for 30 minutes
  • W2 is the weight of water recovered from the pipe 39 for 30 minutes
  • W3 is the W3 measuring diaphragm of the same type and the membrane 2 was prepared separately from the diaphragm 2, were calculated from the weight measured 24 hours Hosei after standing in an atmosphere 23 ° C. relative humidity 55%, 1 cm of the membrane 2 It is per weight.
  • the water transmission rate in the cross-sectional direction of the diaphragm is a value calculated by the following formula using these values.
  • the pressure resistance between the main surfaces of the diaphragm is preferably 60 kPa or more, more preferably 80 kPa or more, and further preferably 100 kPa or more.
  • the pressure resistance between the main surfaces of the diaphragm is the maximum value of the pressure between the main surfaces that can maintain the diaphragm. If the pressure resistance between the main surfaces of the diaphragm is too small, the pressure of the oxidizing agent that is a gas may not be maintained, and the oxidizing agent may leak to the anode. If the oxidant leaks to the anode and the fuel and the oxidant are mixed directly, the power generation efficiency may be reduced.
  • the pressure resistance between the main surfaces of the diaphragm can be measured by the following method using the evaluation cell 100 shown in FIGS.
  • This evaluation cell 100 is formed in the same manner as the evaluation cell 100 used for the measurement of the water transmission rate in the cross-sectional direction of the diaphragm described above.
  • the evaluation cell 100 is installed so that the first main surface and the second main surface of the diaphragm 2 are along the vertical direction, and supply of water and dry air to the evaluation cell 100 in this state is started. 2 ml of water per minute is supplied to the first main surface via a pipe 38 connected to the flow path 18, and 500 ml of dry air per minute is supplied to the second main face via a pipe 48 connected to the flow path 28. Supply. By continuing to supply water as described above, the inside of the first main surface side of the cell 100 is filled with the supplied water, and the first main surface of the diaphragm 2 is always in contact with water. At this time, the evaluation cell 100 is heated using the rubber heaters 15 and 25 provided on the end plates 14 and 24 so that the temperature of the evaluation cell 100 becomes 80 ° C.
  • the pressure adjusting device 43 (for example, a valve) provided in the pipe 49 connected to the flow path 29 while maintaining the temperature of the evaluation cell 100 at 80 ° C. while continuing to supply water and dry air as described above. And the pressure of the dry air to the second main surface is increased so that the pressure of the dry air to the second main surface of the diaphragm 2 is 20 kPa. The pressure of the dry air is measured with a pressure gauge 42 provided in the pipe 49. Thereafter, the pressure regulator 43 continues to supply water and dry air as described above, and maintains the temperature of the evaluation cell 100 at 80 ° C. so that the pressure of the dry air to the second main surface can be maintained at 20 kPa. Adjust the opening.
  • a valve for example, a valve
  • the pressure of the dry air to the second main surface is measured for 10 minutes while maintaining the supply rate of water and dry air, the temperature of the evaluation cell 100, and the opening degree of the pressure adjusting device 43.
  • the withstand pressure between the main surfaces of the diaphragm is evaluated as 0 kPa.
  • the pressure of the dry air to the second main surface is increased, and the same measurement is performed in the order of 40 kPa, 60 kPa, 80 kPa, and 100 kPa.
  • the pressure resistance between the main surfaces of the diaphragm is set to 100 kPa.
  • the case where the pressure can be maintained means that the change in the pressure of the dry air to the second main surface is 1 kPa or less in 10 minutes.
  • a liquid fuel cell (alkaline liquid fuel cell) utilizing the movement of anions
  • fuel is supplied to the anode side and an oxidant such as air is supplied to the cathode side.
  • the reaction on the cathode side requires water in addition to the oxidizing agent.
  • this water is supplied by being humidified from the outside using an auxiliary device such as a humidifier.
  • auxiliary equipment it is desirable to omit auxiliary equipment as much as possible from the viewpoint of miniaturization of the fuel cell and improvement of power generation capacity per unit volume.
  • the diaphragm is also required to have a function of separating the oxidant and the fuel. Since a gas such as air is used as the oxidizing agent, the diaphragm needs to have good pressure resistance against the gas.
  • the water transmission rate in the cross-sectional direction is 40 mol / h ⁇ g or more, And while supplying water to the first main surface, air is supplied to the second main surface opposite to the first main surface and the pressure between the main surfaces measured by increasing the pressure of the air is 80 kPa or more. is there, A diaphragm for a liquid fuel cell is provided.
  • the liquid fuel cell is preferably in alkaline form.
  • the present invention can provide a new diaphragm for a liquid fuel cell suitable for a liquid fuel cell, particularly an alkaline liquid fuel cell.
  • the diaphragm may include a polymer base material and a hydrophilic functional group present on the polymer base material.
  • the material for the polymer substrate those described later as the material for the polymer porous membrane can be used.
  • the polymer substrate may be a porous membrane (polymer porous membrane).
  • the hydrophilic functional group present on the polymer substrate is preferably obtained by carrying out a hydrophilic treatment.
  • the diaphragm for a liquid fuel cell can be formed through a step of preparing a polymer porous membrane and a step of hydrophilizing the polymer porous membrane.
  • hydrophilic treatment is not particularly limited, and graft polymerization treatment, corona treatment, plasma treatment, sputtering treatment, sulfonation treatment, treatment using a surfactant or a hydrophilic polymer, and the like may be used.
  • a solution containing the hydrophilic polymer is applied to the polymer porous membrane, and the hydrophilic polymer membrane is formed on the surface and pore walls of the polymer porous membrane, thereby A hydrophilic functional group may be added to the surface.
  • the amount of the hydrophilic functional group can be adjusted by the thickness of the film formed by applying the hydrophilic polymer, and the average pore diameter of the diaphragm in the film can be adjusted by the thickness of the film. .
  • the hydrophilization treatment is preferably performed using a graft polymerization method from the viewpoint that it can be treated in a uniform system.
  • the diaphragm for a liquid fuel cell includes a polymer substrate and a graft chain introduced into the polymer substrate, and the graft chain preferably has a hydrophilic functional group.
  • Air permeability of the membrane of the present embodiment is preferably in the range of 100 ⁇ 2000sec / 100ml ⁇ inch 2 , more preferably in the range of 200 ⁇ 1000sec / 100ml ⁇ inch 2 . If the air permeability becomes too large, the amount of water permeation and the water permeation rate may decrease. As a result, water required for the reaction at the cathode catalyst may be insufficient, and the reaction efficiency at the cathode catalyst may be reduced.
  • the diaphragm of the present embodiment preferably has a methanol retention rate of 20% or more.
  • the methanol liquid retention rate of the diaphragm is a 23-degree relative humidity measured by using a diaphragm that was previously cut into a rectangle having a long side of 50 mm and a short side of 10 mm and left standing in an atmosphere of 23 ° C. and 50% relative humidity for 12 hours or more.
  • the long side of the rectangle is perpendicular to the liquid level of methanol, and the test piece is held against methanol in a state where the portion 5 mm from the bottom of the test piece is immersed in methanol. Is the ratio of the liquid absorption height from the liquid surface to the long side after maintaining for 1 minute.
  • the methanol retention rate (methanol retention rate) of the diaphragm is measured.
  • the fuel liquid is an aqueous fuel solution in which fuel is dissolved in water, and dissolves an electrolyte.
  • Methanol can be dissolved in water and supplied to the liquid fuel cell as a fuel solution.
  • methanol is relatively similar in structure and molecular weight to water used in fuel solutions. Therefore, it is considered that an appropriate result for evaluating the fuel liquid retention rate of the diaphragm can be obtained by measuring the methanol liquid retention rate.
  • the diaphragm capable of retaining the fuel liquid can hold the electrolyte dissolved in the fuel liquid together with the fuel liquid. Since this electrolyte is responsible for ionic conductivity in the fuel cell, the use of a diaphragm having a good methanol retention rate improves the ionic conductivity and suppresses the electrical resistance in the fuel cell during power generation. If the amount of electrolyte contained in the diaphragm is too small, power generation may not be possible, and even when power generation is possible, the electrical resistance of the fuel cell during power generation may increase. A diaphragm having a methanol liquid retention rate in the above range can satisfactorily retain water contained in the fuel liquid.
  • the diaphragm of this embodiment can contribute to the improvement of the efficiency of the oxygen reduction reaction at the cathode, and can contribute to the improvement of the power generation efficiency of the battery.
  • a liquid fuel cell an alkaline liquid fuel cell
  • fuel is supplied to the anode side and an oxidant such as air is supplied to the cathode side.
  • a liquid fuel cell includes a membrane-electrode assembly (MEA) in which a diaphragm and a catalyst layer are integrated.
  • MEA membrane-electrode assembly
  • auxiliary equipment such as a humidifier.
  • water that has passed through the diaphragm from the anode side to the cathode side In this case, it is conceivable to use a diaphragm that can penetrate water well.
  • the present invention from still another aspect, It is a porous membrane having a methanol retention rate of 20% or more.
  • a diaphragm for a liquid fuel cell is provided.
  • the liquid fuel cell is preferably in alkaline form.
  • the present invention can provide a diaphragm for a liquid fuel cell that can contribute to improving the characteristics of the liquid fuel cell.
  • the liquid fuel cell membrane preferably has a hydrophilic functional group.
  • a hydrophilic functional group By providing a hydrophilic functional group, the liquid retention of methanol can be improved.
  • the hydrophilic functional group may be a functional group having ion conductivity.
  • a known porous film can be used. Examples thereof include a porous film made of an inorganic base material and a porous film made of a polymer base material.
  • a porous film made of a polymer substrate can be formed, for example, by polymerizing a polymerizable monomer having a hydrophilic functional group.
  • a hydrophilic functional group may be introduced on the surface of the porous membrane by performing a hydrophilic treatment.
  • This fuel cell membrane is measured by increasing the air pressure by supplying air to the second main surface opposite to the first main surface while supplying water to the first main surface.
  • the pressure resistance between the main surfaces of the diaphragm is preferably 60 kPa or more, more preferably 80 kPa or more, and further preferably 100 kPa or more.
  • the weight of the membrane of the present embodiment is preferably in the range of 1.05 to 3.0 times (graft rate 5 to 200%) of the weight of the polymer porous membrane, and 1.15 to 2.0 times (graft).
  • the ratio is more preferably in the range of 15% to 100%.
  • the graft ratio indicates the ratio of the weight difference between the weight of the film after graft polymerization and the weight of the film before graft polymerization with respect to the weight of the film before graft polymerization.
  • the material of the polymer porous membrane contained in the diaphragm of the present embodiment is not particularly limited, and a known resin can be used as long as the effect of the invention is not impaired.
  • a known resin can be used as long as the effect of the invention is not impaired.
  • polyolefin resins such as polyethylene and polypropylene, polystyrene resins, epoxy resins such as bisphenol A type epoxy polymers, polysulfide resins such as polyphenylene sulfide, polyether resins such as polyether ketone, polyvinylidene fluoride, ethylene tetrafluoro Fluorine resins such as ethylene and polytetrafluoroethylene
  • polyolefin resins such as polyethylene and polypropylene
  • polystyrene resins epoxy resins such as bisphenol A type epoxy polymers
  • polysulfide resins such as polyphenylene sulfide
  • polyether resins such as polyether ketone
  • At least one selected from the group consisting of polyethylene, polypropylene, polystyrene, bisphenol A type epoxy polymer, polyphenylene sulfide, polyether ketone, polyvinylidene fluoride, ethylene tetrafluoroethylene, and polytetrafluoroethylene is included. It is preferable that at least one selected from the group consisting of polyethylene, polypropylene, polystyrene, polyphenylene sulfide and polyether ketone is included, and at least one selected from the group consisting of polyethylene, polypropylene and polystyrene is included. More preferably.
  • polyethylene is preferable, and low density polyethylene, high density polyethylene, and ultrahigh molecular weight polyethylene are more preferable.
  • High-density polyethylene and ultrahigh molecular weight polyethylene are particularly preferable from the viewpoint of improving the strength and heat resistance of the polymer porous membrane.
  • ultrahigh molecular weight polyethylene having a weight average molecular weight of 500,000 or more, particularly 1,000,000 or more is preferable. These resins may be used alone or in admixture of two or more.
  • These resins may be cross-linked.
  • the crosslinking method is not particularly limited, and a known method such as a method of irradiating the resin with an electron beam or the like, a method of adding a crosslinking agent such as a silane compound or an organic peroxide, and the like can be used.
  • a cross-linked resin is used, the strength of the polymer base material may be improved and the effect of preventing the short circuit of the electrode may be improved.
  • the average pore diameter of the polymer porous membrane is preferably in the range of 1 nm to 1000 nm, more preferably in the range of 2 nm to 500 nm, and still more preferably in the range of 5 nm to 300 nm. If the average pore diameter becomes too large, a short circuit between the electrodes may occur. In addition, the pressure resistance of the diaphragm may be reduced, making it difficult to withstand the pressure of the oxidant. Also, the amount of fuel permeation may increase. If the average pore diameter becomes too small, the water permeability may be lowered. If the water permeation amount is too small, water required for the reaction in the cathode catalyst may be insufficient, and power generation efficiency may be reduced. Since the average pore diameter of the entire diaphragm varies due to graft polymerization performed later, it is preferable to adjust the average pore diameter of the porous membrane in consideration of the variation.
  • the porosity of the polymer porous membrane is preferably in the range of 5 to 95%, more preferably in the range of 10 to 70%, and still more preferably in the range of 10% to 50%. If the porosity is too high, fuel permeation may increase. In addition, the pressure resistance of the diaphragm is reduced, and the pressure of the oxidant may not be maintained. If the porosity is too small, the water permeability may be too small, and the moisture content may be lowered. Since the porosity of the whole diaphragm varies due to graft polymerization performed later, it is preferable to adjust the porosity of the porous membrane in consideration of the variation.
  • the film thickness of the polymer porous film is preferably in the range of 5 ⁇ m to 100 ⁇ m, and more preferably in the range of 10 ⁇ m to 50 ⁇ m. If the film thickness becomes too thin, the film strength may decrease, and defects such as film breakage and pinholes may occur.
  • the fuel permeation amount and water permeation amount may increase. When the permeation amount of the fuel increases, a side reaction in which the fuel and the oxidant directly react with each other occurs, so that the power generation efficiency may deteriorate, and the side reaction may cause deterioration of the cathode catalyst and the like.
  • the resistance (film resistance) as a film in the diaphragm may increase.
  • the water permeability may be too small. If the water permeation amount is too small, water required for the reaction in the cathode catalyst may be insufficient, and power generation efficiency may be reduced.
  • the amount of permeated fuel increases and the fuel is present on the cathode catalyst, a side reaction in which the fuel and the oxidant directly react may occur, resulting in a decrease in power generation efficiency of the battery, and deterioration of the cathode catalyst and the like due to the side reaction.
  • the method for producing the polymer porous membrane is not particularly limited, and a known method such as a dry film formation method or a wet film formation method using thermally induced phase separation or non-solvent induced phase separation can be used.
  • a foaming method using an inorganic foaming agent, an organic foaming agent or a supercritical fluid, a polymer substrate having low compatibility and a phase separation agent are mixed and then phase separated, Extraction or heating using a solvent for extraction (for example, supercritical carbon dioxide), forming a molded body containing components that can be extracted after film formation, phase separation, cutting to form a film
  • a processing method for removing extractable components from the membrane is possible to use.
  • a powdery polymer base material filled in a mold (for example, a cylindrical shape) is heated using water vapor and sintered to form a molded body, and the formed body (for example, a cylindrical block body).
  • the porous film may be obtained by cutting the film into a predetermined thickness.
  • a solvent-containing treatment may be performed after melt-kneading a composition containing a resin and a solvent, cooling after extrusion to form a sheet-like molded product.
  • a laminated polymer porous membrane can be obtained by rolling or uniaxially stretching the sheet-like molded product and then laminating and extracting and removing the solvent. Moreover, after laminating, it may be stretched. It is also possible to bond and laminate immediately after extraction. In that case, the extraction process can be completed in a short time, so that productivity can be improved.
  • the solvent used for preparing the polymer porous membrane is not particularly limited as long as it can dissolve the resin contained in the polymer porous membrane, but a solvent having a freezing point of ⁇ 10 ° C. or lower is preferably used.
  • a solvent having a freezing point of ⁇ 10 ° C. or lower is preferably used.
  • aliphatic or alicyclic hydrocarbons such as decane, decalin and liquid paraffin, and mineral oil fractions having boiling points corresponding to these.
  • the mixing ratio of the resin and the solvent in the composition containing the resin and the solvent cannot be generally determined, but the concentration of the resin in the composition is preferably in the range of 5 to 30% by weight. If the concentration of the resin is too high, kneading is insufficient and it becomes difficult to obtain sufficient entanglement of the polymer chains. If the resin concentration is too low, sufficient strength of the polymer porous membrane may not be obtained.
  • additives such as an antioxidant, an ultraviolet absorber, a dye, a pigment, an antistatic agent, and nucleation are further added as long as the object of the present invention is not impaired. Can be added.
  • the hydrophilic functional group is not particularly limited as long as it is a functional group having hydrophilicity.
  • the hydrophilic functional group is at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, a sulfonic acid group, and a phosphoric acid group. Yes, especially a carboxyl group.
  • the graft chain may not substantially have a functional group having anion exchange ability. “Substantially free” means that the amount of the functional group having anion exchange capacity relative to the weight of the diaphragm is 0.1 mmol / g or less, preferably 0.05 mmol / g or less.
  • functional groups having anion exchange ability include quaternary ammonium bases and quaternary phosphonium bases.
  • the hydrophilic functional group may have a monomer that forms a graft chain (hereinafter sometimes referred to as “graft monomer (M)”), and may be introduced into the graft chain after graft polymerization. That is, the graft monomer (M) may have a hydrophilic functional group or may have a site where a hydrophilic functional group can be introduced.
  • graft monomer (M) may have a hydrophilic functional group or may have a site where a hydrophilic functional group can be introduced.
  • the graft monomer (M) has a carbon-carbon unsaturated bond and a hydrophilic functional group.
  • the graft monomer (M) is not particularly limited, but examples thereof include carboxylic acid monomers such as acrylic acid and methacrylic acid, acrylamide, methacrylamide, 2-hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxy (Meth) acrylic acid derivative monomers such as propyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, vinyl acetate monomers such as vinyl acetate, allylamine, acrylamide, methacrylamide, N-vinyl Examples thereof include nitrogen-containing monomers such as pyrrolidone and N-vinylpyridine, and styrene derivative monomers such as sodium styrenesulfonate.
  • At least one selected from the group consisting of acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-vinylpyrrolidone, N-vinylpyridine, 2-hydroxyethyl methacrylate, and styrene derivative monomers Preferably, at least one selected from the group consisting of acid, methacrylic acid, acrylamide, methacrylamide, N-vinyl pyrrolidone, N-vinyl pyridine, and 2-hydroxyethyl methacrylate is included.
  • the graft monomer (M) of the present embodiment has substantially no functional group having anion exchange ability. “Substantially free” means that the amount of the functional group having anion exchange capacity relative to the weight of the diaphragm is 0.1 mmol / g or less, preferably 0.05 mmol / g or less.
  • functional groups having anion exchange ability include quaternary ammonium bases and quaternary phosphonium bases.
  • the graft monomer (M) may be used for polymerization alone or may be prepared as a solution (graft monomer (M) solution) in which the graft monomer (M) is dissolved in a solvent.
  • the solvent contained in the graft monomer (M) solution is not particularly limited. If a solvent that dissolves the graft monomer (M) but does not dissolve the polymer porous membrane is used, the graft monomer (M), the polymer porous membrane, Is easily separated. In addition, when a solvent capable of dissolving a polymer formed only from the graft monomer (M) as a by-product is used, the polymerization solution can be kept uniform.
  • the solubility of the graft monomer (M), the polymer formed only from the graft monomer (M) and the polymer porous membrane in the solvent is the polymer formed only from the graft monomer (M), the graft monomer (M), and Since it may vary depending on the structure or polarity of the polymer porous membrane, a solvent may be appropriately selected according to the solubility of these compounds. Two or more compounds may be mixed and used as a solvent.
  • Such a solvent include aromatic compounds such as aromatic hydrocarbons such as benzene, toluene and xylene, and phenols such as phenol and cresol.
  • aromatic compounds such as aromatic hydrocarbons such as benzene, toluene and xylene, and phenols such as phenol and cresol.
  • aromatic compound dissolves the polymer composed only of the graft monomer (M) as a by-product, the polymerization solution can be kept uniform.
  • the concentration of the graft monomer (M) in the graft monomer (M) solution may be determined according to the polymerizability of the graft monomer (M) and the target graft ratio. It is preferable to include 20% by weight or more of the graft monomer (M) based on the weight. By using a solution having a concentration of the graft monomer (M) of 20% by weight or more, it is easy to avoid a situation in which the graft reaction does not proceed sufficiently.
  • oxygen in the graft monomer (M) or the graft monomer (M) solution is subjected to a known method such as freeze degassing or bubbling using nitrogen gas. It is preferable to use and remove.
  • the graft chain is introduced into the polymer porous membrane by graft polymerization.
  • This graft chain is bonded to the polymer porous membrane.
  • the graft chain is preferably formed by a radiation graft polymerization treatment from the viewpoint that it can be treated in a homogeneous system. Specifically, it is formed by irradiating a polymer porous membrane with radiation, bringing the polymer porous membrane after radiation irradiation into contact with a graft monomer (M) or a graft monomer (M) solution to cause a graft polymerization reaction. It is preferable.
  • Examples of radiation irradiated to the polymer porous membrane include ionizing radiation such as ⁇ rays, ⁇ rays, ⁇ rays, electron rays, and ultraviolet rays, and ⁇ rays or electron rays are particularly preferable.
  • the irradiation dose is preferably in the range of 1 kGy to 400 kGy, more preferably in the range of 10 kGy to 300 kGy.
  • the graft rate can be controlled by the radiation dose. If the irradiation dose is too low, the graft rate may be lowered. When the irradiation dose increases too much, the mechanical strength of the diaphragm may be reduced due to deterioration of the polymer porous membrane or excessive polymerization reaction.
  • the polymer porous membrane after irradiation may be held at a low temperature (for example, ⁇ 30 ° C. or lower).
  • the graft polymerization is preferably performed in an atmosphere where the oxygen concentration is as low as possible, and is performed in an inert gas atmosphere such as argon gas or nitrogen gas. Is more preferable.
  • the temperature at which the graft polymerization is performed is, for example, 0 ° C. to 100 ° C., particularly 40 to 80 ° C.
  • the reaction time for carrying out the graft polymerization is, for example, about 2 minutes to 12 hours.
  • the graft ratio can be controlled by these reaction temperature and reaction time.
  • graft polymerization reaction a reaction example in a solid-liquid two-phase system will be described.
  • a graft monomer (M) solution containing a graft monomer (M) and a solvent is placed in a container such as glass or stainless steel.
  • vacuum degassing in the graft monomer (M) solution and bubbling with an inert gas (nitrogen gas or the like) are performed.
  • an inert gas nitrogen gas or the like
  • Graft chains are introduced into the polymer constituting the polymer porous membrane by graft polymerization.
  • the obtained membrane is removed from the reaction solution and filtered. Further, in order to remove the polymer composed of only the solvent, the unreacted graft monomer (M), and the graft monomer (M), the obtained film is washed 3 to 6 times with an appropriate amount of solvent and then dried.
  • the solvent a solvent that can easily dissolve the graft monomer (M) and the polymer composed only of the graft monomer (M) and does not dissolve the graft film may be used.
  • water, toluene, acetone or the like can be used as the solvent.
  • the graft monomer (M) has a carbon-carbon unsaturated bond and a site capable of introducing a hydrophilic functional group.
  • the site capable of introducing a hydrophilic functional group is, for example, a halogenated alkyl group such as a halogenated methyl group, a halogenated ethyl group, a halogenated propyl group, and a halogenated butyl group, styrene sulfonic acid, vinyl sulfonic acid or acrylic phosphone.
  • alkyl esters such as acids.
  • graft monomer (M) examples include styrene derivatives such as styrene, chloromethylstyrene, and bromobutylstyrene. These monomers (M) may be used alone or in admixture of two or more. In this embodiment, it is preferable that the graft monomer (M) does not have a functional group having anion exchange ability.
  • the graft chain of the diaphragm does not substantially have a functional group having cation conductivity.
  • the hydrophilic functional group which the diaphragm of this embodiment has is a sulfonic acid group, for example.
  • the diaphragm having the characteristics of the present invention has a pore filled with a hydrophilic gel, a nonporous membrane made of a polymer base material having a hydrophilic functional group, or a polymer material having a hydrophilic functional group. It is the made porous membrane. If necessary, the polymer material having a hydrophilic functional group may have a crosslinked structure.
  • Weight maintenance rate (%) (weight after KOH treatment) ⁇ 100 / (weight before KOH treatment)
  • (F) Pressure resistance test evaluation of pressure resistance between main surfaces
  • a pressure resistance test was performed using the evaluation cell for fuel cell shown in FIGS. 2 to 4 as an evaluation cell, and the pressure resistance between the main surfaces of the diaphragm was evaluated.
  • a diaphragm 2 having a main surface of a square having a side of 4 cm was prepared.
  • the diaphragm 2 was sandwiched between a pair of gaskets 11 and 21 having square openings 11a and 21a each having a length of 2 cm.
  • a pair of separators 12 and 22 with serpentine-structured flow channels 12a and 22a, a pair of current collector plates 13 and 23, and a pair of end plates 14 and 24 are arranged and sandwiched in this order on the outside of the gaskets 11 and 21.
  • the evaluation cell 100 has flow paths 18, 19, 28, and 29.
  • the channels 18 and 19 are channels for supplying and discharging water, respectively, and the channels 28 and 29 are channels for supplying and discharging dry air, respectively.
  • Each flow path 18, 19, 28, 29 has an opening in the end plate.
  • the flow paths 18 and 19 penetrate the end plate 14, the current collector plate 13, and the separator 12, and are connected to the flow path 12a. The same applies to the flow paths 28 and 29.
  • the evaluation cell 100 was installed so that the main surface of the diaphragm 2 was along the vertical direction. Supply of water and dry air to the evaluation cell 100 in this state was started. 2 ml of water per minute is supplied to the main surface on the anode side (first main surface) via a pipe 38 connected to the flow path 18, and 500 ml per minute is supplied to the main surface on the cathode side (second main surface). Dry air was supplied through a pipe 48 connected to the flow path 28. By continuing to supply water as described above, the inside of the first main surface side of the cell 100 was filled with the supplied water, and the first main surface of the diaphragm 2 was always in contact with water.
  • the evaluation cell 100 was heated using the rubber heaters 15 and 25 provided on the end plates 14 and 24 so that the temperature of the evaluation cell 100 became 80 ° C.
  • the temperature of the evaluation cell 100 was measured using a thermocouple 41 installed in the separator 22. Water and dry air were continuously supplied as described above, and the temperature of the evaluation cell 100 was maintained at 80 ° C. for 1 hour.
  • the pressure of the dry air to the second main surface was measured for 10 minutes.
  • the pressure resistance between the main surfaces of the diaphragm was evaluated as 0 kPa.
  • the opening of the pressure regulator 43 is adjusted while maintaining the temperature of the evaluation cell 100 at 80 ° C., and the second main The pressure of the dry air to the second main surface was increased so that the pressure of the dry air to the surface was 40 kPa.
  • the pressure regulator 43 continues to supply water and dry air as described above so that the pressure of the dry air to the second main surface can be maintained at 40 kPa while maintaining the temperature of the evaluation cell 100 at 80 ° C.
  • the opening degree of was adjusted. With the water and dry air supply rates, the temperature of the evaluation cell 100, and the opening degree of the pressure adjusting device 43 maintained, the pressure of the dry air to the second main surface was measured for 10 minutes. When 40 kPa could not be maintained for 10 minutes, the pressure resistance between the main surfaces of the diaphragm was evaluated as 20 kPa.
  • the pressure of dry air to the second main surface was increased, and the same measurement was performed in the order of 60 kPa, 80 kPa, and 100 kPa.
  • the pressure resistance between the main surfaces of the diaphragm was evaluated as 100 kPa.
  • the case where the pressure can be maintained means that the change in the pressure of the dry air to the second main surface is 1 kPa or less in 10 minutes.
  • the water permeation rate was measured according to the following procedure using the evaluation cell for fuel cell shown in FIGS. 2 to 4 as the evaluation cell.
  • a measurement diaphragm a water permeability measurement diaphragm 2 having a square main surface with a side of 4 cm and a W3 measurement diaphragm having a rectangular main surface with a short side of 2 cm and a long side of 3 cm were prepared.
  • the diaphragm 2 for measuring the water transmission rate was sandwiched between a pair of gaskets 11 and 21 having square openings 11a and 21a each having a length of 2 cm.
  • a pair of separators 12 and 22 with flow paths 12a and 22a having a serpentine structure, a pair of current collector plates 13 and 23, and a pair of end plates 14 and 24 are arranged in this order on the outside of the gaskets 11 and 21 so as to sandwich the diaphragm 2 did.
  • Each member was fastened using a fixing component (not shown) such as a bolt so that air and water did not leak from each contact surface of the member, and the evaluation cell 100 was formed.
  • the evaluation cell 100 has flow paths 18, 19, 28, and 29.
  • the channels 18 and 19 are channels for supplying and discharging water, respectively, and the channels 28 and 29 are channels for supplying and discharging dry air, respectively.
  • Each flow path 18, 19, 28, 29 has an opening in the end plate.
  • the flow paths 18 and 19 penetrate the end plate 14, the current collector plate 13, and the separator 12, and are connected to the flow path 12a. The same applies to the flow paths 28 and 29.
  • the evaluation cell 100 was installed so that the main surface of the diaphragm 2 was along the vertical direction. Supply of water and dry air to the evaluation cell 100 in this state was started. 2 ml of water per minute is supplied to the first main surface via a pipe 38 connected to the flow path 18, and 500 ml of dry air per minute is supplied to the second main face via a pipe 48 connected to the flow path 28. Supplied. At this time, the evaluation cell 100 was heated using the rubber heaters 15 and 25 provided on the end plates 14 and 24 so that the temperature of the evaluation cell 100 became 80 ° C. The temperature of the evaluation cell 100 was measured using a thermocouple 41 installed in the separator 22. Water and dry air were continuously supplied to the evaluation cell 100 as described above, and the temperature of the evaluation cell 100 was maintained at 80 ° C. for 1 hour.
  • the water and dry air are continuously supplied as described above, and the water discharged from the pipe 39 connected to the anode-side flow path 19 is collected for 30 minutes while maintaining the temperature of the evaluation cell 100 at 80 ° C. did.
  • the weight of the collected water was W2.
  • the weight of water supplied to the evaluation cell 100 for 30 minutes was defined as W1.
  • the weight per cm 2 of the diaphragm calculated from the measured weight was defined as W3.
  • the water transmission rate in the cross-sectional direction of the diaphragm was calculated according to the following formula.
  • (J) Methanol retention ratio A diaphragm, which was previously cut into a rectangle having a long side of 50 mm and a short side of 10 mm, and left in an atmosphere of 23 ° C. and 50% relative humidity for 12 hours or more, was used as a test piece. Hold the test piece against methanol in a state where the long side of the rectangle is perpendicular to the methanol surface and the 5 mm portion from the bottom of the test piece is immersed in methanol in an atmosphere of 23 ° C and 50% relative humidity. did.
  • the methanol retention rate is the ratio of the liquid absorption height from the liquid surface of methanol after maintaining this state for 1 minute to the long side.
  • the test piece before liquid absorption is opaque, and the test piece which absorbed methanol is translucent. The length of the translucent test piece was measured to obtain the liquid absorption height.
  • a power generation test was conducted at 2 ml of liquid fuel per minute was supplied to the anode side, and 200 ml of dry air was supplied to the cathode side. In this test, whether or not current sweep is possible, the limit current density, and the cell resistance when the maximum output density was developed (measured using the current interruption method. The internal resistance of the cell was measured from the voltage change when the current was instantaneously interrupted. ) And the maximum power density were compared.
  • Example 1 In Example 1, an ultrahigh molecular weight polyethylene porous film having a film thickness of 20 ⁇ m, a porosity of 40%, and an air permeability (Gurley value) of 173 sec / 100 ml ⁇ inch 2 was used as the polymer substrate. By irradiating this ultrahigh molecular weight polyethylene porous film with an electron beam of 45 kGy, free radicals were generated. The ultrahigh molecular weight polyethylene porous film after electron beam irradiation was cooled to ⁇ 70 ° C. and stored until the next step was performed.
  • the obtained graft porous membrane was pulled up and washed with water to wash away excess monomers, and then water on the surface portion was removed to obtain a hydrophilic diaphragm having hydrophilicity.
  • the resulting graft porous membrane had a graft rate of 40%.
  • Each physical property of this diaphragm was measured.
  • This membrane had an air permeability (Gurley value) of 491 sec / 100 ml ⁇ inch 2 . A power generation test was performed using this diaphragm.
  • Example 2 Except for making graft polymerization time into 4 minutes, it implemented similarly to Example 1 and obtained the hydrophilic membrane with a graft ratio of 30%. Each physical property of this diaphragm was measured. This membrane had an air permeability (Gurley value) of 366 sec / 100 ml ⁇ inch 2 . In addition, a power generation test was performed using this diaphragm.
  • Example 1 The ultra high molecular weight polyethylene porous membrane used in Example 1 was used as a membrane without treatment. Each physical property of this diaphragm was measured. This membrane had an air permeability (Gurley value) of 173 sec / 100 ml ⁇ inch 2 . In addition, a power generation test was performed using this diaphragm.
  • a nonporous film of a copolymer of tetrafluoroethylene and ethylene (ETFE, film thickness 50 ⁇ m) was used.
  • This ETFE film was irradiated with an electron beam of 30 kGy on each side (total 60 kGy) under vacuum at room temperature to generate free radicals.
  • the ETFE film after electron beam irradiation was cooled to ⁇ 70 ° C. and stored until the next step was performed.
  • 28 g of 4- (chloromethyl) styrene and 12 g of xylene were mixed to prepare a monomer solution.
  • this monomer solution was bubbled with nitrogen gas to remove oxygen in the monomer solution.
  • the graft membrane after the quaternization treatment was washed with ethanol for 30 minutes, then washed with an ethanol solution containing 1N hydrochloric acid for 30 minutes, and further washed with pure water.
  • a polymer base material was an ETFE film, and a film having a chloride ion type quaternary ammonium base was obtained. Each physical property of this diaphragm was measured. In addition, a power generation test was performed using this diaphragm.
  • Table 1 summarizes the results of battery tests using the diaphragms of Examples 1-2 and Comparative Examples 1-2.
  • PE represents ultrahigh molecular weight polyethylene
  • CMS represents chloromethylstyrene
  • TMA represents trimethylamine.
  • Comparative Example 1 polyethylene porous membrane having no hydrophilic functional group
  • Comparative Example 2 EFE nonporous film
  • current flowed but the internal resistance of the cell was high and the limiting current density was low.
  • Examples 1 and 2 polyethylene porous membrane
  • the limiting current density was higher than that of Comparative Example 2, and the cell resistance when the maximum output density was developed was lower than that of Comparative Example 2.

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Abstract

　La membrane de séparation de pile à combustible liquide selon l'invention est pourvue, par exemple, d'une membrane poreuse polymère et d'une chaîne greffée introduite dans le film poreux polymère. La chaîne greffée contient un groupe fonctionnel hydrophile. Le groupe fonctionnel hydrophile est, de préférence, un groupe hydroxyle, un groupe carboxyle, un groupe amino, etc.
PCT/JP2015/003348 2014-07-03 2015-07-02 Membrane de séparation de pile à combustible liquide et ensemble membrane-électrode pourvu de celle-ci Ceased WO2016002227A1 (fr)

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JP2014137792A JP2016015287A (ja) 2014-07-03 2014-07-03 液体燃料電池用隔膜及びそれを備えた膜−電極接合体
JP2014137790A JP2016015285A (ja) 2014-07-03 2014-07-03 アルカリ形液体燃料電池用隔膜及びそれを備えた膜−電極接合体
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CN106354180A (zh) * 2016-10-14 2017-01-25 上海新源动力有限公司 一种快速调节燃料电池测试台气体温湿度的系统
WO2018173327A1 (fr) * 2017-03-24 2018-09-27 栗田工業株式会社 Dispositif de production d'énergie microbienne

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