Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/20—Manufacture of shaped structures of ion-exchange resins
  • C08J5/22—Films, membranes or diaphragms
  • C08J5/2287—After-treatment
  • C08J5/2293—After-treatment of fluorine-containing membranes
• • 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
  • H01M8/10—Fuel cells with solid electrolytes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/20—Manufacture of shaped structures of ion-exchange resins
  • C08J5/22—Films, membranes or diaphragms
  • C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
  • C08J5/2218—Synthetic macromolecular compounds
  • C08J5/2231—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds
  • C08J5/2243—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds obtained by introduction of active groups capable of ion-exchange into compounds of the type C08J5/2231
  • C08J5/225—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds obtained by introduction of active groups capable of ion-exchange into compounds of the type C08J5/2231 containing fluorine
• • 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
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
  • H01M8/04197—Preventing means for fuel crossover
• • 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
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
  • H01M8/1018—Polymeric electrolyte materials
  • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
  • H01M8/1023—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
• • 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
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
  • H01M8/1018—Polymeric electrolyte materials
  • H01M8/1039—Polymeric electrolyte materials halogenated, e.g. sulfonated polyvinylidene fluorides
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
  • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
  • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C08J2327/16—Homopolymers or copolymers of vinylidene fluoride
• • 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
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/1009—Fuel cells with solid electrolytes with one of the reactants being liquid, solid or liquid-charged
  • H01M8/1011—Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
• • 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 an electrolyte membrane capable of maintaining characteristics even when used for a long time in a polymer electrolyte fuel cell. Specifically, the present invention relates to an electrolyte membrane having excellent adhesion to electrodes in a polymer electrolyte fuel cell.
• Solid polymer fuel cells have high energy density and are expected to be used in a wide range of fields such as household cordier energy sources, portable device power sources, electric vehicle power sources, and simple auxiliary power sources.
• the electrolyte membrane functions as an electrolyte for conducting protons, and at the same time serves as a diaphragm for directly mixing hydrogen, methanol, and oxygen as fuel.
• an electrolyte membrane has a high ion exchange capacity as an electrolyte, is electrically and chemically stable because a current flows for a long time, has a low electrical resistance, a strong mechanical strength of the membrane, a fuel As for hydrogen gas, methanol and oxygen gas, low gas permeability is required.
• fluorinated polymer electrolyte membranes such as naphthion are very expensive due to the complicated synthesis of fluorinated monomers as raw materials, and this is a major obstacle to the practical application of polymer electrolyte fuel cells. It has become.
• Patent Document 1 Japanese Patent Laid-Open No. 9 102322
• Patent Document 2 JP-A-4 220957
• the present invention has been made to overcome the problems of polymer ion exchange membranes including the above-described fluorine-based electrolyte membrane, and has been used for a long time in a polymer electrolyte fuel cell. It is an object of the present invention to provide an electrolyte membrane that can maintain its characteristics even after performing. Specifically, an object of the present invention is to provide an electrolyte membrane excellent in adhesion to electrodes in a polymer electrolyte fuel cell.
• the present inventors have found that the battery characteristics (for example, output, durability, etc.) decrease with long-term use, that is, the adhesion between the electrode and the electrolyte membrane decreases with long-term use.
• the main cause was the insufficient adhesion between the two materials.
• the electrolyte membrane is in a state in which water or the like is retained inside the battery, but the amount of the retained fluid varies depending on the operating conditions of the battery. Changes (swelling and shrinking) occur.
• an electrolyte agent is often used as a binder for a catalyst or the like for the electrode material, and the electrolyte agent also undergoes dimensional changes depending on the liquid retention state, and also softens. These dimensional changes can also be caused by temperature changes during operation and shutdown. These phenomena occur repeatedly during long-term use, and even when the electrode and the electrolyte membrane are in the bonded state at the initial stage, peeling occurs gradually at the interface, and as a result, the battery characteristics deteriorate and recur. I found out.
• the present invention provides an electrolyte membrane in which the initial bonding state (adhesiveness) to the electrode material is unlikely to deteriorate even when the usage condition or environment changes, particularly for use in a polymer electrolyte fuel cell. It is.
• the electrolyte membrane in which a graft chain containing a cation exchange group is added to a polymer substrate composed of an olefin-based or fluorine-based polymer the present inventors have determined the physical properties of the substrate (thermal deformation temperature and area change rate). As a result, the inventors have invented an electrolyte membrane that can maintain its characteristics even after long-term use as a fuel cell.
• a graft chain including a cation exchange group is added to a polymer substrate made of an olefin-based or fluorine-based polymer.
• the electrolyte membrane is characterized by a penetration temperature measured by thermomechanical analysis of 200 ° C or less.
• the dimensional change rate when immersed in a 40 wt% methanol aqueous solution is preferably 40% or less.
• the polymer base material is preferably made of polyvinylidene fluoride.
• an electrolyte membrane capable of maintaining characteristics even after long-term use can be provided. Also, polymer electrolyte fuel cell In the pond, an electrolyte membrane having excellent adhesion to the electrode can be provided.
• the electrolyte membrane for a polymer electrolyte fuel cell of the present invention is produced by adding a graft chain containing a cation exchange group to a polymer substrate made of olefin-based or fluorine-based polymer.
• Power S can be.
• an electrolyte polymer solution in which a catalyst component such as platinum-supported carbon is dispersed is directly applied to the electrolyte membrane by screen printing or the like.
• Examples thereof include a method of evaporating and drying the solvent component of the electrolyte polymer solution after coating on the surface, and a method of transferring the electrolyte polymer solution onto the metal foil or heat resistant polymer film and then transferring it to the electrolyte membrane.
• the electrolyte membrane of the present invention has a penetration temperature measured by thermomechanical analysis of 200 ° C. or less, and by regulating the penetration temperature in this way, the electrolyte membrane and the electrode components It is possible to improve the adhesiveness and obtain excellent battery characteristics. That is, the electrolyte membrane and the electrode component are laminated by using the above-described method and the like, and pressure bonding is performed under the condition that the electrolyte membrane component is heated to a temperature that softens at least the electrolyte membrane component in the range of about 120 to 200 ° C. The material film is easily deformed, and the adhesiveness with the electrode component can be dramatically improved.
• the electrolyte polymer component in the electrode component is selected to be softened or molten in the same temperature range, the adhesion can be further improved.
• the adhesion state during processing is good, more efficient proton transfer is possible, and excellent characteristics can be obtained even when battery output is reduced.
• Examples of the polymer substrate that can be used in the present invention include fluorine-based polymers and olefin-based polymers.
• fluorine-based polymers include fluorine-based polymers and olefin-based polymers.
• PVDF polyvinylidene fluoride
• Low density and high density polyethylene, polypropylene, etc. can be used.
• These polymer base materials are preferably subjected to a crosslinking treatment by irradiation with radiation or the like in advance so that a prescribed penetration temperature can be satisfied, because a dimensional change rate accompanying liquid retention can be reduced.
• a prescribed penetration temperature can be satisfied, because a dimensional change rate accompanying liquid retention can be reduced.
• High durability against electrochemical reactions inside the battery. PVDF is preferred because it favors molecules.
• a monomer having a bur group or a monomer in which a part of hydrogen bonded to the bulu group is substituted with a different functional group (hereinafter referred to as these). Can be used to polymerize using radiation.
• the bull monomer may be a single type or a mixture of plural types of monomers.
• the bulur monomer specifically, one represented by the chemical formula (1) can be used.
• R 2 is 1 H, _CH 3 , -CH 2 CK — CH 2 OH,
• Aromatic monomers that contain a benzene ring are more preferred.
• a crosslinking agent having a plurality of unsaturated bonds having graft reactivity in the molecule can be used.
• Graft polymerization of the monomer onto the polymer substrate may be a so-called pre-irradiation method in which the substrate is irradiated with radiation and then reacted with the monomer, or polymerization is performed by simultaneously irradiating the substrate and the monomer with radiation.
• the so-called simultaneous irradiation method can be used. It is preferable to use the pre-irradiation method because it does not graft onto the base material and produces a small amount of homopolymer.
• pre-irradiation methods There are two pre-irradiation methods, a polymer radical method in which irradiation of a polymer substrate is performed in an inert gas and a peroxysite method in which irradiation is performed in an oxygen-existing atmosphere. Can also be used.
• An example of the pre-irradiation method will be described below. First, after inserting a polymer substrate into a glass container, the container is vacuum degassed and replaced with an inert gas atmosphere. Next, the container containing the base material is irradiated with an electron beam or ⁇ -ray at -10 to 80 ° C, preferably near room temperature:! To 500 kGy, and after bubbling of the inert gas without oxygen, it is freeze-dehydrated.
• the monomer can be used as a single monomer solution, a plurality of monomer mixtures, or a monomer solution dissolved or diluted with a suitable solvent.
• the graft polymerization is usually carried out at 30 to: 150 ° C, preferably 40 to 80 ° C.
• the graft ratio of the polymer base material after graft polymerization is 6 to 150% by weight, more preferably 10 to 100% by weight.
• the graft ratio can be changed by irradiation dose, polymerization temperature, polymerization time, and the like.
• a cation exchange group is introduced into the polymer substrate into which the graft chain has been introduced.
• the cation exchange group is obtained by graft polymerizing a bull monomer to a polymer substrate and then introducing it into the formed graft chain or graft polymerizing a bull monomer having a cation exchange group.
• a graft chain and a cation exchange group can be simultaneously introduced into the substrate.
• a bull monomer having a derivative of a cation exchange group may be used and converted to a cation exchange group after the formation of the graft chain.
• Cation exchange group Although there is no particular limitation, for example, a sulfone group, a carboxyl group, and the like can be used.
• the cation exchange group can be introduced into the graft chain by a known method.
• the conditions for introducing a sulfone group are disclosed in JP-A-2001-348439. Specifically, a graft film substrate is placed in a chlorosulfonic acid solution having a concentration of 0.2 to 0.5 mol / L using 1,2-dichloroethane as a solvent at room temperature to 80 ° C:! Let it soak for hours. After reacting for a predetermined time, the membrane is thoroughly washed with water.
• sulfonating agent necessary for the sulfonation reaction concentrated sulfuric acid, sulfur trioxide, sodium thiosulfate and the like can be used, and any type can be used as long as it can introduce a sulfone group.
• the carboxyl group and the like are not particularly limited as long as each can be introduced.
• the ion exchange group is introduced at the time when the grafting reaction is completed. Therefore, it is not necessary to perform this treatment.
• the suitable process is performed after completion
• the ability to obtain a carboxyl group that is a cation exchange group can be obtained by hydrolysis.
• the electrolyte membrane of the present invention has a penetration temperature measured by thermomechanical analysis of 200 ° C or lower.
• the amount of indenter penetration at 150 ° C. measured by thermomechanical analysis is preferably 50% or less of the film thickness before measurement.
• the electrolyte membrane according to the present invention preferably has an area change rate of 40% or less by impregnating with a 40 wt% aqueous methanol solution. If the area change rate exceeds 40%, it becomes difficult to maintain the adhesion with the electrode obtained by defining the softening temperature (penetration temperature) of the electrolyte membrane. Regarding this characteristic, the graft ratio of the electrolyte membrane, sulfo It is possible to control by the introduction amount of ion exchange groups such as hydrogen groups and the degree of crosslinking (addition amount of crosslinking agent).
• the ion exchange capacity of the polymer electrolyte membrane according to the present invention is preferably 0.3 to 6. Omeq / g, and more preferably 0.5 to 2. OmeqZg. Masle.
• the ion exchange capacity is the ion exchange amount (meqZg) per lg of the dry electrolyte membrane.
• the ion exchange capacity is less than 0.3 meqZg, the ion exchange capacity is insufficient, and the membrane resistance is high, which is preferable.
• the ion exchange capacity is higher than OmeqZg, as in the dimensional change rate described above, the expansion when containing liquid is large. This is not preferable because it becomes too much to maintain the adhesion with the electrode.
• the polymer electrolyte membrane according to the present invention preferably has an electrical conductivity at 25 ° C of 0.03 ⁇ — ⁇ m— 1 or more, and more preferably 0.05 ⁇ — ⁇ ⁇ 1 or more. Is more preferable. This is because if the electrical conductivity is less than 0.03 ⁇ — 1 , the membrane resistance is large and sufficient output cannot be obtained.
• the thickness of the electrolyte membrane can be cited.
• the film thickness is too thin, the film strength decreases and breaks easily, and defects such as pinholes tend to occur.
• Those in the range of 300 xm, more preferably 20 to 150 ⁇ m are useful.
• a fuel cell there is a direct methanol fuel cell using methanol as a fuel.
• a naphthoion membrane DuPont
• DuPont which is a fluorine-based electrolyte membrane
• the intermolecular Since there is no cross-linking structure, methanol, which is a swollen fuel, permeates the membrane and diffuses from the anode (fuel electrode) to the power sword (air electrode), resulting in a serious problem that power generation efficiency decreases.
• the electrolyte membrane of the present invention improves the adhesion to the electrode by regulating the softening temperature (penetration temperature) and the area change rate, so that the methanol permeation is very difficult to swell. An effect can be acquired also in the point which suppresses property.
• a PVDF film with a thickness of 50 ⁇ m formed by melt extrusion was placed in a glass separable container with a cock (inner diameter 3 cm , height 20 cm), and after degassing, it was filled with 1 atm of argon gas.
• 6Q Co_ ⁇ rays were irradiated at a dose rate of lOkGyZhr and a dose of 60 kGy at room temperature.
• the film was completely immersed in the mixed solution.
• An electrolyte membrane was obtained in accordance with the procedure of Example 1 except that the heating condition at the time of graft polymerization was changed to 60 ° C. for 5 hours.
• An electrolyte membrane was obtained in accordance with the procedure of Example 1 except that the heating condition at the time of graft polymerization was set at 80 ° C. for 3 hours.
• An electrolyte membrane was obtained according to the procedure of Example 1 except that naphth ion 112 was used as the polymer substrate.
• An electrolyte membrane was obtained according to the procedure of Example 1 above, except that an FEP film (thickness 50 am) was used as the polymer substrate and the heat treatment during graft polymerization was 12 hours at 60 ° C.
• An electrolyte membrane was obtained in accordance with the procedure of Example 1 except that the heating condition during graft polymerization was 12 hours at 80 ° C. (Characteristic evaluation method)
• the graft ratio was calculated by the following formula.
• G (W2-W1) X 100 / W1
• the ion exchange capacity I of the electrolyte membrane is expressed by the following equation.
• n (acid group) Molar amount of acid group of electrolyte membrane (mM)
• n (acid group) was measured by the following procedure.
• the electrolyte membrane is 1M (M
• the electrical conductivity of the electrolyte membrane is measured by the alternating current method (New Experimental Chemistry Course 19, Polymer Chemistry ⁇ II>, p992, Maruzen). It uses an ordinary membrane resistance measurement cell and LCR meter (E— 4925A; Hulett Packard). The membrane resistance (Rm) was measured. The cell was filled with 1M sulfuric acid solution, the resistance between the platinum electrodes (distance 5 mm) was measured with and without the membrane, and the electrical conductivity (specific conductivity) of the membrane was calculated using the following equation.
• T Needle penetration temperature
• TMA thermomechanical analyzer
• Measuring device TMA / SS6000 manufactured by SSI Nano Technology
• This laminate was immersed in a water-methanol mixture (40 wt% aqueous methanol solution) and heated in a sealed state at 60 ° C for 30 minutes, so that the electrolyte membrane was swollen.
• the stacked body was taken out, dried by heating and blowing in an atmosphere at 60 ° C. for 30 minutes, and dried to return to a room temperature atmosphere.
• a total of 10 cycles were tested with this as one cycle, and the number of cycles until the electrode and electrolyte membrane completely peeled and the adhesion state at the end of the 10 cycles were confirmed.

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• 2004
  • 2004-12-15 JP JP2004362575A patent/JP2006172858A/ja active Pending
• 2005
  • 2005-12-12 KR KR1020077015387A patent/KR20070095313A/ko not_active Ceased
  • 2005-12-12 WO PCT/JP2005/022770 patent/WO2006064762A1/ja not_active Ceased
  • 2005-12-12 DE DE602005026722T patent/DE602005026722D1/de not_active Expired - Lifetime
  • 2005-12-12 US US11/793,059 patent/US20080044710A1/en not_active Abandoned
  • 2005-12-12 AT AT05814459T patent/ATE500627T1/de not_active IP Right Cessation
  • 2005-12-12 EP EP05814459A patent/EP1863110B1/en not_active Expired - Lifetime
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