JP4672992B2 - Solid polymer electrolyte composite membrane, solid electrolyte composite membrane / electrode assembly, and fuel cell using the same - Google Patents

Description

  The present invention relates to a solid polymer electrolyte composite membrane, a solid electrolyte composite membrane / electrode assembly, and a fuel cell using the same.

  In recent years, a polymer electrolyte fuel cell (PEFC) using an ion exchange membrane as an electrolyte membrane has been attracting particular attention recently because it operates at a low temperature, has a high output density, and can be downsized. Development is proceeding at a rapid pace to be applied to distributed power supplies for business use, mobile power supplies for automobiles, and the like.

  A polyperfluorocarbon sulfonic acid electrolyte membrane is commercially available as an electrolyte membrane for a polymer electrolyte fuel cell. Typical examples include Nafion (registered trademark: manufactured by Dupont, USA), Aciplex (registered trademark: manufactured by Asahi Kasei Kogyo Co., Ltd.), Flemion (registered trademark: manufactured by Asahi Glass Co., Ltd.), and the like.

  In order to spread PEFC in earnest, it is essential to improve performance, extend the service life, and reduce costs. The polyperfluorocarbon sulfonic acid electrolyte membrane requires a fluorine chemical process and is a super fine chemical material whose use is limited to salt electrolysis and fuel cell applications. Therefore, it is difficult to significantly reduce the cost.

  In order to improve the performance of fuel cells by increasing the efficiency and increasing the power density, it is necessary to reduce the ionic conduction resistance of the solid polymer electrolyte membrane and improve the ionic conductivity. As a method for reducing the ion conduction resistance of the solid polymer electrolyte membrane, there is a reduction in the film thickness. The reduction of the film thickness causes problems such as a decrease in the mechanical strength of the film and a decrease in workability and handleability.

In order to solve the above problems, various attempts have been made to reinforce the electrolyte membrane with a reinforcing material.
For example, Patent Document 1 discloses a solid polymer electrolyte composite membrane in which pores of a porous thin film made of polyolefin having a weight average molecular weight of 5 × 10 ⁵ or more are filled with an ion exchange resin.
However, it is not clear how to configure the region that should function as an electrolyte and the region that should function as a reinforcing material of the solid polymer electrolyte composite membrane, and therefore the electrochemical performance and durability as a polymer electrolyte membrane. The challenge is how to achieve both.

  In Patent Document 2, (i) a part of the void in the porous membrane substrate is filled with a solvent solution of a polymer electrolyte having a contact angle with the porous membrane substrate of less than 90 °, Next, (ii) a polymer electrolyte composite membrane in which the remaining voids of the porous membrane substrate are filled with a solvent solution of a polymer electrolyte having a contact angle of 90 ° or more with the porous membrane substrate. A manufacturing method is disclosed. However, in the manufacture of the electrolyte membrane, a plurality of electrolyte solutions are prepared, and the manufacturing process increases and the manufacturing becomes complicated. Furthermore, the durability when the fuel cell is operated is not always satisfactory. In addition, similar to the technique described in Patent Document 1, this technique also has a problem of how to achieve both electrochemical performance and durability as a polymer electrolyte membrane.

  Further, Patent Document 3 describes a porous film having high strength and excellent affinity with an electrolytic solution. Examples of the use include non-aqueous electrolyte batteries such as lithium battery separators and capacitors. Yes.

Japanese Unexamined Patent Publication No. 64-22932

JP 2003-41031 A JP 2002-367590 A

  An object of the present invention is to provide a solid polymer electrolyte composite membrane excellent in durability, a solid electrolyte membrane / electrode assembly, and a fuel cell using the same.

  As a result of intensive studies, the present inventors have invented a novel structure of a solid polymer electrolyte composite membrane comprising a solid polymer electrolyte and a polyolefin porous membrane. Representative embodiments of the present invention are as follows.

  (1) A solid polymer electrolyte composite comprising a solid polymer electrolyte layer and a polyolefin porous membrane sandwiched between the solid polymer electrolyte layers, and comprising the solid polymer electrolyte filled with the polyolefin porous membrane The ratio of the thickness (t) of the polyolefin porous membrane to the thickness (D) of the solid polymer electrolyte composite membrane is 15 to 90%, and the solid polymer electrolyte has a sulfoalkylated side. A solid polymer electrolyte composite membrane which is an aromatic hydrocarbon polymer compound contained in a chain.

  (2) An electrode catalyst layer is formed, and an anode and an electrode catalyst layer are formed, and a solid polymer electrolyte composite membrane sandwiched between the cathodes is provided. The solid polymer electrolyte composite membrane includes a solid polymer electrolyte layer and a solid polymer electrolyte layer. A solid polymer having a polyolefin porous membrane sandwiched between molecular electrolyte layers, the polyolefin porous membrane being filled with the above-mentioned solid polymer electrolyte, and having a thickness (t) of the polyolefin porous membrane A solid electrolyte membrane / electrode assembly in which the ratio to the electrolyte composite membrane (D) is 15 to 90%, and the solid polymer electrolyte is an aromatic hydrocarbon polymer compound containing a sulfoalkylated product in the side chain.

  (3) A solid polymer electrolyte composite membrane formed with an electrode catalyst layer and having an anode and an electrode catalyst layer sandwiched between the cathode and the solid polymer electrolyte composite membrane comprises the solid polymer electrolyte layer and the solid polymer electrolyte membrane. A solid polymer having a polyolefin porous membrane sandwiched between molecular electrolyte layers, the polyolefin porous membrane being filled with the above-mentioned solid polymer electrolyte, and having a thickness (t) of the polyolefin porous membrane A solid electrolyte membrane / electrode assembly in which the ratio to the electrolyte composite membrane (D) is 15 to 90%, and the solid polymer electrolyte is an aromatic hydrocarbon polymer compound containing a sulfoalkylated product in the side chain; A fuel cell having a gas diffusion sheet connected to each of both surfaces and a separator connected to each of the gas diffusion sheets.

  The polyolefin porous membrane is filled with the solid polymer electrolyte, and the polymer electrolyte layers existing on both surfaces of the polyolefin porous membrane are in close contact with each other to have a continuous structure. Therefore, the composite membrane obtained has a small dimensional change and is excellent in durability. Further, by defining the thickness of the electrolyte layer present on both surfaces of the polyolefin porous membrane, the characteristics of the composite membrane as an electrolyte can be maintained and the durability can be maintained.

  The ratio of the thickness (t) of the polyolefin porous membrane to the thickness (D) of the solid polymer electrolyte composite membrane is preferably 20 to 80%. Further, when two layers of the polyolefin porous membrane are present in the solid polymer electrolyte composite membrane, the dimensional change rate of the composite membrane can be further suppressed. This polyolefin porous membrane exists mutually apart. The solid polymer electrolyte is preferably a sulfoalkylated product of polyethersulfone.

  The polyolefin porous membrane used in the present invention preferably contains a thermoplastic elastomer (rubber-like elastic body), norbornene rubber or the like as a component for crosslinking the polyolefin resin for the purpose of improving heat resistance. The content of the thermoplastic elastomer or norbornene rubber can be appropriately selected from the viewpoint that the dispersion is sufficient and a homogeneous porous film can be obtained. After filling a polyolefin porous membrane containing norbornene rubber with an electrolyte polymer, the rubber component is cross-linked to increase the strength of the polyolefin porous membrane and suppress dimensional changes. The norbornene rubber is described in, for example, Patent Document 3. Such a polyolefin porous membrane preparation method is described in detail in the above publication.

The polyolefin porous membrane itself preferably contains ultrahigh molecular weight polyethylene having a weight average molecular weight of 1 × 10 ⁶ or more. The polyolefin porous membrane used in the present invention preferably contains an ultrahigh molecular weight polyolefin resin. Examples of the ultrahigh molecular weight polyolefin resin include homopolymers and copolymers of olefins such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and 1-hexene, and mixtures thereof. Then, from the viewpoint of increasing the strength of the resulting porous membrane, an ultrahigh molecular weight polyethylene resin having a weight average molecular weight of 1 × 10 ⁶ or more is preferably used. It is also possible to use a porous membrane that has been sulfonated or sulfoalkylated in advance by a known method.

  The polyolefin porous membrane used in the present invention preferably has a porosity of 40 to 90%. When the porosity is less than 40%, the resistance of the solid polymer electrolyte composite membrane is large, and the performance of the fuel cell is deteriorated. If the porosity is larger than 90%, it is difficult to suppress the dimensional change, and it becomes difficult to obtain the effect of increasing the strength due to the composite.

  As a method of combining the polyolefin porous membrane and the polymer electrolyte material, a method of impregnating the polyolefin porous membrane with a solution or dispersion of the polymer electrolyte material and then drying it to form a film, or a polymer electrolyte material Applying the solution to a polyolefin porous membrane, drying and forming a film, bringing the polyolefin porous membrane into contact with a polymer electrolyte solution under reduced pressure, then returning to normal pressure and impregnating, drying and forming a film The method of performing etc. are mentioned.

The polyolefin porous membrane of the present invention preferably has a thickness (t) of 15% to 90% with respect to the thickness (D) of the polymer electrolyte composite membrane. Particularly preferably, it is 20% to 80%.
If this ratio is less than 15%, the mechanical strength and dimensional stability of the polymer electrolyte composite membrane are not sufficient, and if it exceeds 90%, the ionic conduction resistance of the polymer electrolyte composite membrane increases, so the fuel cell performance is satisfactory. It is no longer possible.

  The polyolefin porous membrane of the present invention can be arranged in a plurality of layers in the polymer electrolyte composite membrane. By disposing a plurality of polyolefin porous membrane layers, mechanical strength and dimensional stability are further improved. However, since the composite film having this structure increases the number of manufacturing steps, the cost may increase. Therefore, it is desirable to suppress the increase in cost by devising the manufacturing method.

  The electrolyte membrane material used in the present invention is preferably sulfomethylated polyethersulfone or sulfopropylated polyethersulfone, which is a sulfoalkylated product of polyethersulfone, from the viewpoint of durability. Other electrolyte membrane materials include sulfoalkylated engineered plastic materials such as sulfoalkylated polyetheretherketone, sulfoalkylated polyetherethersulfone, sulfoalkylated polysulfone, sulfoalkylated polysulfide, and sulfoalkylated polyphenylene. Used.

  The sulfonic acid equivalent of the polymer electrolyte material used in the present invention is preferably in the range of 0.5 to 2.0 meq / g dry resin, more preferably 0.7 to 1.6 meq / g dry resin. When the sulfonic acid equivalent is lower than this range, the ion conduction resistance of the membrane increases, and when it is high, it is easily dissolved in water, which is not preferable.

Although there is no restriction | limiting in particular in the thickness of the polymer electrolyte composite film of this invention, 10-200 micrometers is preferable.
20-100 micrometers is especially preferable. A thickness of more than 10 μm is preferable to obtain a membrane strength that can withstand practical use, and a thickness of less than 200 μm is preferable in order to reduce membrane resistance, that is, improve power generation performance. The most preferable thickness is 30 to 80 μm, and the most preferable ratio of t / D is 35 to 65%. Additives such as antioxidants can be added to the polyolefin porous membrane and solid polymer electrolyte material of the present invention as needed within a range not impairing the object of the present invention.

  The polymer electrolyte composite membrane of the present invention is used not only for hydrogen-oxygen fuel cells but also for direct methanol fuel cells (DMFCs) that use liquid alcohol as a fuel to supply directly to the fuel cells. be able to.

  According to the present invention, since the chemical affinity between the polyolefin porous membrane and the polymer electrolyte is good, the adhesion between the two is excellent, and the dimensional change rate of the polymer electrolyte composite membrane is small. A polymer electrolyte composite membrane can be provided.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

Example 1
(Preparation of polyolefin porous membrane 1)
A raw material resin in which 3 parts by weight of ultrahigh molecular weight polyethylene having a weight average molecular weight of 2.5 × 10 ⁶ and 14 parts by weight of high density polyethylene having a weight average molecular weight of 6.8 × 10 ⁵ are mixed, and 83 parts by weight of liquid paraffin; Were mixed to prepare a polyethylene composition solution. Next, 0.375 parts by weight of an antioxidant was mixed with 100 parts by weight of this polyethylene composition solution. This mixed solution was filled in an autoclave equipped with a stirrer and stirred at 200 ° C. for 90 minutes to obtain a uniform solution. This solution was extruded from a T die at 200 ° C. by an extruder having a diameter of 45 mm and taken up by a cooling roll cooled to 20 ° C., thereby forming a gel sheet having a thickness of 1.8 mm. The obtained sheet was set in a biaxial stretching machine, and simultaneous biaxial stretching was performed 5 × 5 times at a temperature of 105 ° C. and a film forming speed of 5 m / min.

The obtained stretched membrane was washed with methylene chloride to extract and remove the remaining liquid paraffin. After drying at room temperature, heat setting was performed at 90 ° C. for 30 seconds to obtain a polyolefin porous membrane 1 having a thickness of 20 μm and a porosity of 40%. For the porosity, the value calculated by the following formula [1] from the weight W (g) per unit area S (cm ² ), the average thickness t (μm) and the density d (g / cm ³ ) of the film is used. did.

Porosity (%) = (1- (10 ⁴ × W / S / t / d)) × 100 (1)
The heat shrinkage rate of the polyolefin porous membrane 1 was measured by standing a 10 cm square sample in a state of no tension at 105 ° C. for 8 hours. The heat shrinkage rate in the vertical direction was 25% and the heat shrinkage rate in the horizontal direction. Was 19%.

(Formation of electrolyte composite membrane)
Prior to preparation of the electrolyte composite membrane, sulfomethylated polyethersulfone SM-PES (1.1 meq / g) was dissolved in N, N-dimethylacetamide to prepare a 25 wt% electrolyte solution. The polyolefin porous membrane 1 was impregnated with this solution, and the electrolyte solution was cast on a glass substrate. Then, the electrolyte composite membrane was produced by heating and drying at 80 ° C. for 30 minutes and then at 120 ° C. for 30 minutes to remove the solvent in the solution. The thickness of the obtained electrolyte composite membrane was 40 μm. FIG. 2 shows a sectional structural view of this solid polymer electrolyte composite membrane. 1 is a solid polymer electrolyte composite membrane, 7 is an electrolyte layer, and 8 is a porous layer impregnated with an electrolyte.

  The ratio of the thickness (t) of the polyolefin porous membrane to the thickness (D) of the solid electrolyte composite membrane of this example was 50%.

(Integrated electrode electrolyte)
As an anode and a cathode, an electrode catalyst in which platinum was supported on carbon black at 50 wt% was used. A Nafion (registered trademark) solution (concentration 5 wt%, manufactured by Aldrich) was weighed into this electrode catalyst at a ratio of 1: 9 by weight of the electrode catalyst to the Nafion solution, and mixed while volatilizing the solvent to obtain an electrode catalyst paste. It was. The electrode catalyst paste was applied onto a PTFE sheet, to form a catalyst layer area 9cm ² and dried by volatilization of the solvent. The amount of platinum in the catalyst layer was 0.3 mg / cm ² per unit area. Two of the catalyst layers were used and pressed on both sides of the polymer electrolyte composite membrane by hot pressing.

(Battery performance)
Battery performance was measured using the single polymer electrolyte fuel cell power generator single cell shown in FIG. 1 is a solid polymer electrolyte composite membrane, 2 is an anode, 3 is a cathode, 4 is a membrane / electrode assembly, 5 is a current collector, and 6 is a separator. Hydrogen was used as the anode supply gas, air was used as the cathode supply gas, the temperature of the fuel cell was 70 ° C., the fuel utilization rate of the anode was 70%, and the oxygen utilization rate in the cathode air was 40%.

(Dimensional change rate)
The polymer electrolyte composite membrane or the electrolyte membrane was cut into a 6 cm square to obtain a test piece. After holding this sample piece at 25 ° C. and 55% RH for 24 hours or more, the vertical and horizontal dimensions of the film were measured to calculate the film area (S ₀ ). Next, the test pieces were immersed for 24 hours in deionized water at 80 ° C., vertical after immersion of the membrane, measured membrane area lateral dimensions (S ₁₎ was calculated. The dimensional change rate (ΔS) was calculated by the following equation [2].

ΔS (%) = (S ₁ −S ₀ ) / S ₀ × 100 (2)
Table 1 shows the voltage at a current density of 0.25 A / cm ² as the above dimensional change rate and battery performance.

( Reference Example 1 )
(Preparation of polyolefin porous membrane 2)
Ultra-high molecular weight polyethylene resin 15 parts by weight of liquid paraffin 85 parts by weight of the weight average molecular weight 2 × 10 ^6, were uniformly mixed in a slurry state was subjected to melt kneading using a biaxial extruder at a temperature of 160 ° C.. The obtained melt-kneaded product was extruded from a 16 mm fishtail die and quenched into a sheet by a 1.0 mm sizing die cooled to 0 ° C. These rapidly crystallized sheet-like molded products were rolled by a heat press at a temperature of 120 ° C. until the sheet thickness became 0.8 mm, and then immediately cooled to 15 ° C. by a water-cooled cold press for 2 minutes. Next, the obtained sheet-like molded product was simultaneously biaxially stretched 4 × 4 times in length and width at a temperature of 125 ° C., forcibly cooled to 20 ° C. for 1 minute by air cooling with a spot cooler, and then removed using heptane. Liquid paraffin was extracted by solvent treatment to obtain a sheet-like molded product. The polyolefin porous membrane 2 was obtained by performing heat setting treatment at 130 ° C. for 20 minutes.

  The total draw ratio was 200 times. The heat shrinkage rate of the polyolefin porous membrane 2 was measured by leaving a 10 cm square sample at 105 ° C. for 8 hours in a no-tension state. The heat shrinkage rate in the vertical direction was 5% and the heat shrinkage rate in the horizontal direction was It was 8%. Various characteristics were examined in the same manner as in Example 1 except that this polyolefin porous membrane 2 was used.

  The ratio of the thickness (t) of the polyolefin porous membrane to the thickness (D) of the solid electrolyte composite membrane of this example was 63%.

(Example 3)
(Preparation of polyolefin porous membrane 3)
15 parts by weight of ultra high molecular weight polyethylene resin having a weight average molecular weight of 1.2 × 10 ⁶ , 1.22 parts by weight of norbornene rubber (manufactured by Zeon Corporation, trade name: Nosolex NB) and liquid paraffin (freezing point: −15 ° C., 40 85 parts by weight of kinematic viscosity at 59 ° C. (the same applies hereinafter) was uniformly mixed into a slurry and melt kneaded at a temperature of 160 ° C. using a twin screw extruder. The obtained melt-kneaded product was extruded from a 16 mm fishtail die and quenched into a sheet by a 7.5 mm sizing die cooled to 0 ° C. These rapidly crystallized sheet-like molded products were rolled by a heat press at a temperature of 115 ° C. until the sheet thickness became 0.6 mm, and then immediately cooled to 15 ° C. for 2 minutes by a water-cooled cold press.

  Next, the obtained sheet-like molded product was simultaneously biaxially stretched 4.4 × 4.4 times in length and breadth at a temperature of 120 ° C., forcedly cooled to 20 ° C. in 1 minute by air cooling with a spot cooler, and then heptane was A solvent removal treatment was performed to extract liquid paraffin, and a sheet-like molded product was obtained. The obtained sheet-like molded product was heat-treated at 85 ° C. for 12 hours to thermally crosslink norbornene rubber, and then heat-fixed at 120 ° C. for 2 hours to obtain a polyolefin porous membrane 3. The heat shrinkage rate of the polyolefin porous membrane 3 was measured by leaving a sample of 10 cm square at 105 ° C. for 8 hours in a no-tension state. The heat shrinkage rate in the vertical direction was 4% and the heat shrinkage rate in the horizontal direction was 4%. 7%. Example 1 is the same as Example 1 except that this polyolefin porous membrane 3 was used. The thickness of the composite film was 40 μm. The various characteristics were examined in the same manner as in Example 1.

  The ratio of the thickness (t) of the polyolefin porous membrane to the thickness (D) of the solid electrolyte composite membrane of this example was 40%.

Example 4
The battery performance was examined in the same manner except that the polyolefin porous membrane having a porosity of 60% was used in Example 3. The ratio of the thickness (t) of the polyolefin porous membrane to the thickness (D) of the solid electrolyte composite membrane of this example was 45%.

(Example 5)
(Preparation of polyolefin porous membrane 4)
12 parts by weight of ultra high molecular weight polyethylene resin having a weight average molecular weight of 1.2 × 10 ⁶ , 3 parts by weight of olefinic thermoplastic elastomer (manufactured by Sumitomo Chemical Co., Ltd., trade name: TPE821, softening temperature: 102 ° C.), norbornene 1.22 parts by weight of rubber (manufactured by ZEON, trade name: Northolex NB) and 85 parts by weight of liquid paraffin (solidifying point: −15 ° C., kinematic viscosity at 40 ° C. of 59 cst, the same applies hereinafter) are uniformly mixed in a slurry state. The mixture was melt kneaded at a temperature of 160 ° C. using a twin screw extruder.

  The obtained melt-kneaded product was extruded from a 16 mm fishtail die and quenched into a sheet by a 7.5 mm sizing die cooled to 0 ° C. These rapidly crystallized sheet-like molded products were rolled by a heat press at a temperature of 115 ° C. until the sheet thickness became 0.6 mm, and then immediately cooled to 15 ° C. in a water-cooled cold press for 2 minutes. Next, the obtained sheet-like molded product was simultaneously biaxially stretched 4.4 × 4.4 times in length and breadth at a temperature of 120 ° C., forcedly cooled to 20 ° C. in 1 minute by air cooling with a spot cooler, and then heptane was A solvent removal treatment was performed to extract liquid paraffin, and a sheet-like molded product was obtained. The obtained sheet-like molded product was heat-treated at 85 ° C. for 12 hours to thermally crosslink norbornene rubber, and then heat-fixed at 120 ° C. for 2 hours to obtain a polyolefin porous membrane 4. The total draw ratio was 258 times. This porous membrane 1 had a thickness of 16 μm and a porosity of 41%. The thermal contraction rate of the polyolefin porous membrane 4 was measured by standing a 10 cm square sample in a state of no tension at 105 ° C. for 8 hours. The thermal contraction rate in the vertical direction was 5% and the thermal contraction rate in the horizontal direction. Was 9%.

  The ratio of the thickness (t) of the polyolefin porous membrane to the thickness (D) of the solid electrolyte composite membrane of this example was 40%.

(Example 6 , Reference Example 2 , Comparative Example 1)
A polymer electrolyte composite membrane was prepared in the same manner as in Example 3 except that the polyolefin porous membrane shown in Table 1 was used, and various characteristics were examined. The results are shown in Table 1. Comparative Example 1 shows the results when no polyolefin porous membrane was used.

The ratio of the thickness (t) of the polyolefin porous membrane to the thickness (D) of the solid electrolyte composite membrane in Example 6 was 20%. Further, the ratio of the thickness (t) of the polyolefin porous membrane to the thickness (D) of the solid electrolyte composite membrane in Reference Example 2 was 80%. The ratio of porous film thickness d / composite film thickness D in the comparative example was 0%.

The thickness of the composite film obtained in Example 6 and Reference Example 2 was 50 μm.

  As is apparent from Table 1, it is clear that the polymer electrolyte composite membrane according to the present invention has extremely small dimensional stability and exhibits excellent characteristics as compared with the electrolyte membrane of the comparative example. Moreover, the characteristics as an electrolyte are not lost, and it can be said that it is superior to the case of a polymer electrolyte alone.

Sectional drawing of the fuel cell power generation device single cell in connection with this invention. 1 is a cross-sectional view of a solid polymer electrolyte composite membrane according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid polymer electrolyte composite film, 2 ... Anode, 3 ... Cathode, 4 ... Membrane / electrode assembly, 5 ... Current collector, 6 ... Separator, 7 ... Electrolyte layer, 8 ... Porous layer.

Claims (6)

A polyolefin porous membrane, and a sulfoalkylated aromatic hydrocarbon polymer filled with a solid polymer electrolyte solution composed of a sulfoalkylated aromatic hydrocarbon polymer compound in the pores of the polyolefin porous membrane Sulfoalkylated aromatic hydrocarbons laminated on both sides so as to sandwich a polyolefin porous membrane containing a solid polymer electrolyte comprising a compound and the solid polymer electrolyte of the impregnated sulfoalkylated aromatic hydrocarbon polymer compound A solid polymer electrolyte composite membrane integrated with a solid polymer electrolyte membrane made of a polymer polymer, wherein the polyolefin porous membrane has a porosity of 40 to 60%, and its thickness (t) Is 10 to 20 μm, and the ratio of the thickness (t) to the thickness (D) of the solid polymer electrolyte composite membrane is 20 to 80%. Body polymer electrolyte composite membrane. The solid polymer electrolyte composite membrane according to claim 1, wherein the polyolefin porous membrane contains a thermoplastic elastomer or norbornene rubber. A solid polymer electrolyte composite membrane sandwiched between a positive electrode on which an electrode catalyst layer is formed and a negative electrode on which an electrode catalyst layer is formed, the solid polymer electrolyte composite membrane comprising a polyolefin porous membrane and the polyolefin porous membrane The solid polymer electrolyte comprising a sulfoalkylated aromatic hydrocarbon polymer compound, which is impregnated with a solution of a solid polymer electrolyte comprising a sulfoalkylated aromatic hydrocarbon polymer compound in the pores of the porous membrane; A solid comprising a sulfoalkylated aromatic hydrocarbon polymer compound laminated on both sides so as to sandwich a polyolefin porous membrane containing a solid polymer electrolyte comprising the impregnated sulfoalkylated aromatic hydrocarbon polymer compound The polymer electrolyte membrane is integrated, the porosity of the polyolefin porous membrane is 40 to 60%, and the thickness (t) is 1 A ～20Myuemu, and the solid electrolyte membrane / electrode assembly ratio to the thickness (D) of the solid polymer electrolyte composite membrane of a thickness (t) is characterized in that 20 to 80%. 4. The solid electrolyte membrane / electrode assembly according to claim 3, wherein the polyolefin porous membrane contains a thermoplastic elastomer or norbornene rubber. A solid polymer electrolyte composite membrane sandwiched between a positive electrode on which an electrode catalyst layer is formed and a negative electrode on which an electrode catalyst layer is formed. The solid polymer electrolyte composite membrane includes a polyolefin porous membrane and the polyolefin porous membrane A solid polymer electrolyte composed of a sulfoalkylated aromatic hydrocarbon polymer compound, which is impregnated with and filled with a solution of a solid polymer electrolyte composed of a sulfoalkylated aromatic hydrocarbon polymer compound in the pores of the membrane, and said impregnation The solid polymer electrolyte membrane composed of the sulfoalkylated aromatic hydrocarbon polymer compound laminated on both sides of the polyolefin porous membrane containing the prepared sulfoalkylated aromatic hydrocarbon polymer compound A molecular electrolyte composite membrane, the porosity of the polyolefin porous membrane is 40 to 60%, and the thickness (t) is 10 to 20 μm, And a solid electrolyte membrane / electrode assembly ratio to the thickness (D) of the solid polymer electrolyte composite membrane of a thickness (t) is 20-80%, and the gas diffusion sheet which are respectively connected to both sides thereof, further A fuel cell comprising unit cells each having a separator connected to the outside thereof. The fuel cell according to claim 5, wherein the polyolefin porous membrane contains a thermoplastic elastomer or norbornene rubber.

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