JP4554541B2 - Proton conducting electrolyte and fuel cell - Google Patents

Description

  The present invention relates to a proton conductive electrolyte suitable as a fuel cell material and a fuel cell using the same.

As electrolytes for fuel cells, fluorinated polyethylene sulfonic acid membranes, which are also used in applications such as salt electrolysis, seawater desalination, and water treatment, are widely used for reasons such as excellent proton conductivity and chemical stability. ing. For example, a Nafion film, a Flemion film, an Aciplex film, a Dow film (all of which are trade names) are commercially available. However, since these electrolyte membranes contain fluorine, they are not preferable from the environmental viewpoint and are expensive.
As electrolyte membranes that do not contain fluorine, polystyrene sulfonic acid has been proposed as an ion exchange resin for water treatment, an ion exchange membrane, and the like, and a sulfonated aromatic polymer and the like for a fuel cell (Patent Document 1, Non-Patent Document 1). . However, these have insufficient heat resistance and chemical stability for practical use as a fuel cell.

In addition, from the viewpoint of power generation efficiency and system efficiency of the fuel cell and long-term durability of the constituent members, in particular, at an operating temperature of about 100 ° C. to 200 ° C., operating conditions of no humidification or low humidity of 50% or less relative humidity. However, there is a demand for a fuel cell in which good power generation performance can be stably obtained over a long period of time. However, even when the above material is used for the electrolyte membrane, it is difficult to obtain stable performance.
Japanese National Patent Publication No. 11-502245 T. T. Kobayashi, M .; Rikukawa, K .; Sanui, N .; Ogata, Solid State Ionics, 106, 1998, p. 219

  The present invention has been made in view of the above circumstances, and is a proton suitable as a polymer electrolyte fuel cell material capable of stably obtaining good power generation performance for a long period of time even under the above operating conditions. It is an object of the present invention to provide a conductive electrolyte and a fuel cell using the same.

  As a result of intensive studies to solve the above problems, the present inventor has paid attention to a polymer having good solubility and high heat resistance even at high molecular weight, and has excellent proton conductivity and heat resistance as a precursor. As a result, it was found that polyvinylsulfamic acid having the above-mentioned properties was obtained, and the present invention was completed.

  That is, the proton conductive electrolyte of the present invention is characterized by including a polyvinylsulfamic acid copolymer represented by the following general formula (1).

（但し、一般式（１）中、Ｒ_１はＨ，ＣＯＯＨ，ＣＯＮＨＳＯ_３Ｈ，芳香族基であり、Ｒ_２はＨ，ＣＨ_３であり、Ｒ_３はＣＯＯＨ,アルコキシ基，ハロゲン基，エステル基，芳香族基を示し、ｍ，ｎはそれぞれ平均重合度であって１００〜１００００００の整数である。）

(In the general formula (1), R ₁ is H, COOH, CONHSO ₃ H, aromatic group, R ₂ is H, CH ₃ , R ₃ is COOH, alkoxy group, halogen group, ester group. , Represents an aromatic group, and m and n are average degrees of polymerization, respectively, and are integers of 100 to 1,000,000.)

  In addition, the proton conductive electrolyte of the present invention is configured by mixing polyvinyl sulfamic acid represented by the above general formula (1) and polyamide sulfamic acid represented by the following general formula (2). It is also good.

（但し、一般式（２）中、Ａｒ^１，Ａｒ^２は各々独立に芳香族環又は芳香族環を含む基を示し、ａ，ｂは、０≦ａ≦２，０≦ｂ≦２，且つａ＋ｂ＝２を満たす数であり、ｎは平均重合度であって１００〜１００００００の整数である。）

(In the general formula (2), Ar ¹ and Ar ² each independently represent an aromatic ring or a group containing an aromatic ring, and a and b are 0 ≦ a ≦ 2, 0 ≦ b ≦ 2, and (It is a number satisfying a + b = 2, and n is an average degree of polymerization and is an integer of 100 to 1,000,000.)

  In the proton conductive electrolyte of the present invention, a mixture of the polyvinyl sulfamic acid represented by the general formula (1) and the polyamide sulfamic acid represented by the general formula (2). The ratio is preferably in the range of 1: 1 to 1: 9 by mass ratio.

The fuel cell of the present invention comprises a pair of electrodes and an electrolyte membrane disposed between the electrodes, and the electrolyte membrane is composed of the proton conductive electrolyte of the present invention.
Further, the fuel cell of the present invention may be configured such that the proton conductive electrolyte of the present invention is contained in a part of the electrode.

  According to the present invention, a proton conductive electrolyte excellent in proton conductivity and heat resistance can be realized by adopting a configuration including the polyvinyl sulfamic acid copolymer. Further, by using the proton conductive electrolyte of the present invention as an electrolyte membrane for a fuel cell, even when the operating temperature is 100 ° C. or higher and 200 ° C. or lower and no humidification or relative humidity is 50% or less, the current density is high, A high-power, long-life polymer electrolyte fuel cell can be provided.

  Hereinafter, the proton conductive electrolyte and the fuel cell of the present invention will be described in detail.

"Proton conducting electrolyte"
(Polyvinylsulfamic acid)
The proton conductive electrolyte of the present invention is characterized by containing a polyvinylsulfamic acid copolymer represented by the following general formula (1).

上記一般式（１）中、Ｒ_１はＨ，ＣＯＯＨ，ＣＯＮＨＳＯ_３Ｈ，芳香族基であり、Ｒ_２はＨ，ＣＨ_３であり、Ｒ_３はＣＯＯＨ,アルコキシ基，ハロゲン基，エステル基，芳香族基を示し、ｍ，ｎはそれぞれ平均重合度であって１００〜１００００００の整数である。
芳香族基としては、フェニル基、ナフチル基等が挙げられるが、何ら限定されるものでは無い。

In the general formula (1), R ₁ is H, COOH, CONHSO ₃ H, aromatic group, R ₂ is H, CH ₃ , R ₃ is COOH, alkoxy group, halogen group, ester group, aromatic M and n are average polymerization degrees, respectively, and are integers of 100 to 1000000.
Examples of the aromatic group include a phenyl group and a naphthyl group, but are not limited in any way.

  In the present invention, it is preferable that the average degree of polymerization of the polyvinylsulfamic acid copolymer represented by the general formula (1): n / m is in the range of 3/7 to 7/3. Average polymerization degree: When the ratio of n / m is less than 3/7, sufficient proton conductivity cannot be obtained, and when the ratio of n / m exceeds 7/3, the polymer is dissolved in water.

The polyvinylsulfamic acid copolymer contained in the proton conductive electrolyte of the present invention has good solubility in a solvent since a methylene group is introduced as shown in the general formula (1). Thereby, the introduction rate of the functional group of the polyvinylsulfamic acid copolymer is increased, and proton conductivity is improved.
Moreover, the polyvinyl sulfamic acid copolymer represented by the general formula (1) can be easily synthesized with a high molecular weight. When the polyvinyl sulfamic acid copolymer is synthesized with a high molecular weight, the heat resistance is improved with an increase in the molecular weight.
As described above, the proton conductive electrolyte of the present invention can be suitably used as an electrolyte membrane of a fuel cell even when a polyvinyl sulfamic acid copolymer is used alone.

(Polyamide sulfamic acid)
The proton conductive electrolyte of the present invention has a structure obtained by mixing polyvinyl sulfamic acid represented by the above general formula (1) and polyamide sulfamic acid represented by the following general formula (2). can do.

上記一般式（２）中、Ａｒ^１，Ａｒ^２は各々独立に芳香族環又は芳香族環を含む基を示し、ａ，ｂは、０≦ａ≦２，０≦ｂ≦２，且つａ＋ｂ＝２を満たす数であり、ｎは平均重合度であって１００〜１００００００の整数である。

In the general formula (2), Ar ¹ and Ar ² each independently represent an aromatic ring or a group containing an aromatic ring, a and b are 0 ≦ a ≦ 2, 0 ≦ b ≦ 2, and a + b = 2, n is an average degree of polymerization and is an integer of 100 to 1000000.

  In the present invention, the functional group introduction rate: a / b of the polyvinylsulfamic acid represented by the general formula (2) is preferably in the range of 80% to 100%. When the functional group introduction rate: a / b is less than 80%, sufficient proton conductivity cannot be obtained.

As described above, the proton conductive electrolyte of the present invention has excellent heat resistance when the high molecular weight polyvinylsulfamic acid copolymer represented by the general formula (1) is synthesized. A durable electrolyte is obtained. On the other hand, the polyamide sulfamic acid represented by the above general formula (2) is easy to process and has a high functional group introduction rate, so that excellent proton conductivity can be obtained.
By mixing the polyvinyl sulfamic acid copolymer represented by the general formula (1) and the polyamide sulfamic acid represented by the general formula (2), it has excellent heat resistance, In addition, it is possible to obtain a proton conductive electrolyte having strength and flexibility.

Here, when the molecular weight of the polyamide sulfamic acid is increased in order to improve the heat resistance of the polyamide sulfamic acid represented by the general formula (2), if the molecular weight becomes too high, There exists a problem that the reaction rate of group introduction falls.
In the present invention, the mixed form as described above maintains a high functional group introduction rate without increasing the molecular weight of the polyamide sulfamic acid represented by the general formula (2). A proton conductive electrolyte having excellent proton conductivity and heat resistance can be obtained by mixing the polyvinyl sulfamic acid represented by the above general formula (1) with a molecular weight.

  The mixing ratio of the polyvinyl sulfamic acid represented by the general formula (1) and the polyamide sulfamic acid represented by the general formula (2) is from 1: 1 to 1: 9 in terms of mass ratio. It is preferable to be in the range. By setting the mixing ratio in the above range, the proton conductivity and heat resistance of the proton conductive electrolyte can be further improved.

“Proton-Conducting Electrolyte Manufacturing Method”
(Polyvinylsulfamic acid)
Examples of the method for synthesizing the polyvinylsulfamic acid represented by the general formula (1) used in the proton conductive electrolyte of the present invention include a method of synthesizing a raw material polymer by sulfamidation.
When the raw material polymer is synthesized by sulfamidation, for example, it can be synthesized by the following method.

First, a raw material polymer having at least COOH as a starting polymer, such as polyacrylic acid, is dissolved in dehydrated N, N′-dimethylformamide (DMF), and then thionyl chloride is gradually added dropwise under a nitrogen atmosphere. The polymer solution is stirred at room temperature for 24 hours.
Next, dehydrated dichloromethane is mixed with a predetermined amount of amidosulfuric acid and triethylamine to form an amidosulfuric acid triethylamine salt. This solution is gradually added dropwise to the polymer solution under a nitrogen atmosphere and stirred at room temperature for 16 hours.
Subsequently, after distilling off the solvent in the reaction solution under reduced pressure at a temperature of 50 ° C., pure water is added to the viscous material, followed by stirring at room temperature for 1 hour. Then, the precipitate is filtered off, washed with pure water, and then heated and vacuum dried at a temperature of 70 ° C. for 24 hours to obtain a light brown powdered polyvinyl sulfamic acid triethylamine salt. This powder of polyvinyl sulfamic acid triethylamine salt is dissolved in DMF and passed through a cation exchange resin for proton exchange. Then, the treatment liquid is concentrated, dropped into pure water to filter out precipitates, washed with pure water, and then heated and dried at 70 ° C. for a whole day and night. Famic acid can be obtained.

  The method for synthesizing polyvinylsulfamic acid used for the proton conductive electrolyte of the present invention is not limited to the above method. For example, a method may be used in which a vinyl monomer is used as a raw material, and a sulfamic acid group is previously introduced into the vinyl monomer before polymerization.

(Polyamide sulfamic acid)
When synthesizing the polyamide sulfamic acid represented by the above general formula (2) used for the proton conductive electrolyte of the present invention, for example, the following method can be used.

When synthesizing polyamide sulfamic acid, it is preferable to carry out by a method of sulfamidating the side chain carboxylic acid of polyamic acid from the viewpoint of easy synthesis.
In particular, it is preferable that the side chain carboxylic acid group of the polyamic acid is converted to an acid chloride, reacted with an amidosulfuric acid triethylamine salt, and further subjected to cation exchange.
An example of a synthesis scheme of this polyamidesulfamic acid is shown below.

As shown in the above synthesis scheme, the polyamic acid of the general formula (5) used as the starting polymer is, for example, a polymer of an aromatic tetraacetic acid dianhydride of the general formula (3) and an aromatic diamine of the general formula (4). It can be produced by condensation. Ar ^1, Ar ² , and n in the general formulas (3) to (5) are the same as those in the general formula (2) (target product).

By mixing the polyamic acid (5) and thionyl chloride (SOCl ₂ ) in an amide solvent with stirring at room temperature or low temperature for several hours to 24 hours, the polyamic acid (5) has a side chain carboxylic acid. All or at least a part is converted to an acid chloride group (acid chloride). In the example shown in the general formula (6), only one of the side chain carboxylic acids of the polyamic acid (5) is converted into an acid chloride group and the other remains as a carboxylic acid. Can also be converted to acid chloride groups. Examples of the amide solvent used at this time include N, N′-dimethylacetamide, N, N′-dimethylformamide and the like. After completion of the reaction, the reaction solution is poured into methanol or the like, and the precipitate is filtered and washed to separate the produced polymer (6).

The obtained polymer (6) and amidosulfuric acid triethylamine salt (NH ₂ SO ₃ H · N (C ₂ H ₅ ) ₃ ) were stirred and mixed in an amide solvent at room temperature or low temperature for several hours to 24 hours. By doing so, the polyamide sulfamic acid triethylamine salt of the general formula (7) is synthesized. In the example shown in the general formula (7), only one of the side chains of the polyamic acid (5) that has been converted to an acid chloride by the above reaction is converted to a sulfamate, but as described above, the other side chain If the carboxylic acid is converted to an acid chloride, the other side chain can be converted into a sulfamate. As the amide-based solvent used in this case, the same amide solvent as that used in the acid chloride reaction is used. After completion of the reaction, the reaction solution is poured into methanol or the like, and the precipitate is filtered and washed to separate the produced polymer (7).

  Finally, the resulting solution of the polyamidesulfamic acid triethylamine salt (7) (for example, N, N′-dimethylacetamide solution, etc.) is passed through a cation exchange resin to convert the cation exchange (sulfamide acid salt). Converted to sulfamic acid) and protonated. The treatment liquid is poured into methanol, dichloromethane, chloroform, or the like, and the precipitate is filtered and washed to obtain the target polyamic acid derivative represented by the general formula (2).

The polyamic acid derivative (1) of this example has a structure in which a sulfamic acid group is introduced only in a part of the side chain of the polyamic acid as a result of the above reactions. Since each reaction form of the side chain is not limited, it is possible to convert not only a part of the side chain of the polyamic acid but also the entire side chain into a sulfamic acid group, for example.
Further, as described above, a and b in the polyamic acid derivative represented by the general formula (1) are 0 ≦ a ≦ 2, 0 ≦ b ≦ 2, and a + b = 2, and each functional group is Exist in different proportions.

The proton conductive electrolyte of the present invention may contain components other than polyvinyl sulfamic acid and polyamide sulfamic acid as necessary within a range not departing from the gist of the present invention.
For example, in order to increase the strength of the obtained film, a fluorine-containing polymer such as polytetrafluoroethylene can be used in combination as a reinforcing agent.
In addition, a basic nitrogen-containing polymer, oxygen-containing polymer, sulfur-containing polymer, and the like can be used in combination as an ion complex electrolyte.
Further, ortho-phosphoric acid, metaphosphoric acid, polyphosphoric acid and the like can be used together to form a gel electrolyte.

  As described above, the proton-conducting electrolyte of the present invention includes a polyvinylsulfamic acid copolymer having good solubility and high heat resistance even at high molecular weight. In addition, a proton conductive electrolyte excellent in heat resistance can be realized.

"Fuel cell"
In FIG. 1, the schematic diagram of the single cell which comprises the fuel cell of this embodiment is shown. A single cell (fuel cell) 1 shown in FIG. 1 includes an oxygen electrode (electrode) 2, a fuel electrode (electrode) 3, and a proton conductive electrolyte of the present embodiment sandwiched between the oxygen electrode 2 and the fuel electrode 3. A membrane 4 (hereinafter may be referred to as an electrolyte membrane 4), an oxidant distribution plate 5 having an oxidant flow path 5a disposed outside the oxygen electrode 2, and a fuel disposed outside the fuel electrode 3. It is composed of a fuel distribution plate 6 having a flow path 6a, and operates under conditions of an operating temperature of 100 ° C. to 200 ° C. and a humidity of no humidification or a relative humidity of 50% or less.
Further, in the fuel cell of the present embodiment, in the above configuration, the electrolyte membrane 4 is the above-described proton conductive electrolyte of the present invention. Moreover, it can be set as the structure by which the proton conductive electrolyte of this invention contained in the oxygen electrode 2 and a part of fuel electrode 3. FIG.

  The fuel electrode 3 and the oxygen electrode 2 are each generally composed of porous catalyst layers 2a and 3a and porous carbon sheets (carbon porous bodies) 2b and 3b that hold the catalyst layers 2a and 3a, respectively. The catalyst layers 2a and 3a contain an electrode catalyst (catalyst), a hydrophobic binder for solidifying and molding the electrode catalyst, and a conductive material.

  The catalyst is not particularly limited as long as it is a metal that promotes the oxidation reaction of hydrogen and the reduction reaction of oxygen. For example, lead, iron, manganese, cobalt, chromium, gallium, vanadium, tungsten, ruthenium, iridium, palladium, platinum, There may be mentioned rhodium or an alloy thereof. An electrode catalyst can be constituted by supporting such a metal or alloy on activated carbon.

  As the hydrophobic binder, it is preferable to use the proton conductive electrolyte according to the present invention, but other resins can be used, for example, a fluororesin having hydrophobicity can be used. Among the fluororesins, those having a melting point of 400 ° C. or less are preferable. Examples of such fluororesins include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinylidene fluoride, tetrafluoroethylene / hexafluoroethylene copolymer. A resin excellent in hydrophobicity and heat resistance such as a polymer and perfluoroethylene can be used. By adding the hydrophobic binder, it is possible to prevent the catalyst layers 2a and 3a from being wetted excessively by the water generated in response to the power generation reaction, and the fuel gas and oxygen in the fuel electrode 3 and the oxygen electrode 2 can be prevented. Can be prevented.

  Further, the conductive material may be any material as long as it is an electrically conductive material, and examples thereof include various metals and carbon materials. Examples thereof include carbon black such as acetylene black, activated carbon and graphite, and these are used alone or in combination.

  As described above, the catalyst layers 2a and 3a may be configured to contain the proton conductive electrolyte according to the present invention instead of the hydrophobic binder or together with the hydrophobic binder. By adding the proton conductive electrolyte according to the present invention, the proton conductivity in the fuel electrode 3 and the oxygen electrode 2 can be improved, and the internal resistance of the fuel electrode 3 and the oxygen electrode 2 can be reduced.

The oxidant distribution plate 5 and the fuel distribution plate 6 are made of a conductive metal or the like, and function as a current collector by joining to the oxygen electrode 2 and the fuel electrode 3 respectively. Oxygen and fuel gas are supplied to the fuel electrode 3. That is, the fuel electrode mainly containing hydrogen is supplied to the fuel electrode 3 through the fuel flow path 6 a of the fuel flow distribution plate 6, and the oxidant flow path 5 a of the oxidant flow distribution plate 5 is supplied to the oxygen electrode 2. Through this, oxygen as an oxidizing agent is supplied.
The hydrogen supplied as fuel may be supplied by hydrogen generated by reforming hydrocarbon or alcohol, and oxygen supplied as oxidant is supplied in a state of being contained in air. Also good.

  In this single cell 1, hydrogen is oxidized on the fuel electrode 3 side to generate protons, which are conducted through the electrolyte membrane 4 to reach the oxygen electrode 2, and protons and oxygen are electrochemically connected to the oxygen electrode 2. It reacts to produce water and generates electrical energy.

  According to the fuel cell, even in an operating temperature range of 100 ° C. or higher and 200 ° C. or lower with no humidification or a relative humidity of 50% or lower, the current density is high, the output is high, and the life is long. A polymer electrolyte fuel cell that stably exhibits power generation performance for a long period of time can be obtained, and can be suitably used for automobiles, home power generation, or portable devices.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited by the following example.

Example 1
"Production of electrolyte membrane"
First, 7.21 g of polyacrylic acid (manufactured by Acros) was dissolved in 1 L of dehydrated N, N′-dimethylformamide (DMF), and then 29.7 g of thionyl chloride was gradually added dropwise under a nitrogen atmosphere. The polymer solution was stirred at room temperature for 24 hours.
Next, 48.5 g of amidosulfuric acid (manufactured by Kishida Chemical Co., Ltd.) and 50.6 g of triethylamine were mixed with 200 mL of dehydrated dichloromethane to produce an amidosulfuric acid triethylamine salt, and this solution was gradually added to the polymer solution under a nitrogen atmosphere. The solution was added dropwise and stirred at room temperature for 16 hours.
Next, after the solvent in the reaction solution was distilled off under reduced pressure at a temperature of 50 ° C., 1 L of pure water was added to the viscous body, and the mixture was stirred at room temperature for 1 hour. Then, the precipitate was separated by filtration, washed with pure water, and then heated and dried under vacuum at 70 ° C. for 24 hours to obtain 21.5 g as a light brown powder (polyethylsulfamic acid triethylamine salt).
20 g of this polyvinylsulfamic acid triethylamine powder was dissolved in 1 L of DMF and passed through 2.5 L of a cation exchange resin (Amberlyst 15JWET manufactured by Organo) to perform proton exchange. Then, the treatment liquid is concentrated to 100 mL, dropped into 1 L of pure water, and the precipitate is filtered off, washed with pure water, and then heated and dried at 70 ° C. all day and night to obtain a light brown powder. As a (polyvinylsulfamic acid), 8.8 g (yield 70%) was obtained.

Was identified for the obtained light brown ^powder, 1 H-NMR spectrum _(DMSO-d 6, 500MHz) at _{1.25-1.65 (br, -CH 2 -)} , 2.10-2.33 ( The spectrum of br, -CH-) is shown, and further, the absorption (1715 cm ^-1 (v _{C = O} )) derived from the carbonyl group and the absorption derived from the sulfonic acid group (1179, 1020 cm ^-1 (v _{S = O} ) in the IR spectrum. )).

The above polymer is soluble in DNF, N, N′-dimethylacetamide (DMAc), N-methylpyrrolidine (NMP), dimethylsulfoxide (DMSO), etc., and insoluble in water, methanol, chloroform, hexane, benzene and toluene. there were.
When the TG / DTA measurement of the polymer was performed, the 10% thermal decomposition temperature (T _d10% ) was 260 ° C., indicating excellent heat resistance.
The ratio of n / m was 68/32 from the elemental analysis of sulfur.

  When the obtained polymer was dissolved in DMAc, cast on a glass plate, and heated and dried at 60 ° C., a light brown transparent film was obtained.

"Proton conductivity measurement"
The proton conductive electrolyte membrane of Example 1 was sandwiched between disc-shaped platinum electrodes having a diameter of 13 mm, and the ionic conductivity was determined by measuring complex impedance. The graph of FIG. 2 shows the temperature dependence of proton conductivity.
As shown in Table 1, the proton conductive electrolyte membrane of Example 1 had an ionic conductivity at 150 ° C. of 1.1 × 10 ⁻³ Scm ⁻¹ .

"Fuel cell evaluation"
Next, carbon powder carrying 50% by mass of platinum was added to the DMAc solution of the electrolyte membrane prepared in Example 1 and sufficiently stirred to obtain a suspension. At this time, the weight ratio of the platinum-supported carbon powder and the proton conductive electrolyte was adjusted to 2: 1 by the weight ratio of the solid content. This suspension was applied onto a carbon porous body (porosity 75%) and dried to obtain a porous electrode for a fuel cell.
The electrolyte membrane obtained in Example 1 was sandwiched between the pair of porous electrodes to form a single cell. When hydrogen was supplied to the fuel and air was supplied to the oxidant and a power generation test was performed at 150 ° C., the open circuit voltage was 0.900 V and a voltage of 0.484 V was obtained at a current density of 100 mA / cm ² . .

(Examples 2 to 6)
"Other examples of electrolyte membrane"
Instead of the polyacrylic acid used in Example 1, the polymers shown in Table 1 below were used as raw materials, and the polymers synthesized by the same method as in Example 1 were mixed in the proportions shown in Table 1 below. Measurement of proton conductivity and evaluation of the fuel cell were performed using the electrolyte membrane produced by the same method as described above.
In addition, as for B component shown in Examples 2-4, a and b in a formula are a: b = 1.6: 0.4, About B component shown in Examples 5 and 6, a and b were a: b = 1.9: 0.1.

  A list of raw materials and electrolyte components in each of the above examples is shown in Table 1, and a list of evaluation measurement results is shown in Table 2.

As shown in Table 2, the electrolyte membrane using the proton conductive electrolyte obtained in Examples 2 to 6 also has proton conductivity at 150 ° C. of 8.8 × 10 ⁻⁴ Scm ⁻¹ (Example 6). It became the range of -1.3 * 10 < ^-3 > Scm < ^-1 > (Example 2), and favorable proton conductivity was obtained. Further, as in Example 1, a high-quality fuel cell was obtained by using these proton conductive electrolytes.

(Comparative example)
In the same manner as in Example 1, a sulfonated polyetheretherketone was dissolved in NMP to prepare a solution, which was cast on a glass plate and dried by heating at 60 ° C. As a result, a light yellow transparent film was obtained. Proton conductivity was measured at 150 ° C. using the membrane thus prepared, but no conductivity was exhibited.

  The proton conductive electrolyte of the present invention is excellent in proton conductivity and heat resistance, and is preferably used for an electrolyte membrane and an electrode of a fuel cell. By using the proton conductive electrolyte of the present invention, a solid polymer having a high current density, high output, and long life even when the operating temperature is 100 ° C. or higher and 200 ° C. or lower and no humidification or relative humidity is 50% or less. A fuel cell of the type can be provided.

It is a figure which illustrates typically an example of the fuel cell using the proton-conductive electrolyte of this invention, and is the schematic which shows the cross section of a single cell. It is a figure explaining an example of the proton conductive electrolyte of this invention, and is a graph which shows the temperature dependence of proton conductivity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Single cell (fuel cell), 2 ... Oxygen electrode (electrode), 3 ... Fuel electrode (electrode), 4 ... Proton conductive electrolyte membrane (proton conductive electrolyte)

Claims (5)

A proton conductive electrolyte comprising a polyvinylsulfamic acid copolymer represented by the following general formula (1).

(In the general formula (1), R ₁ is H, COOH, CONHSO ₃ H, aromatic group, R ₂ is H, CH ₃ , R ₃ is COOH, alkoxy group, halogen group, ester group. , Represents an aromatic group, and m and n are average degrees of polymerization, respectively, and are integers of 100 to 1,000,000.) Proton conduction characterized in that the polyvinyl sulfamic acid represented by the general formula (1) shown in claim 1 and the polyamide sulfamic acid represented by the following general formula (2) are mixed. Electrolyte.

(In the general formula (2), Ar ¹ and Ar ² each independently represent an aromatic ring or a group containing an aromatic ring, and a and b are 0 ≦ a ≦ 2, 0 ≦ b ≦ 2, and (It is a number satisfying a + b = 2, and n is an average degree of polymerization and is an integer of 100 to 1,000,000.)   The mixing ratio of the polyvinyl sulfamic acid represented by the general formula (1) and the polyamide sulfamic acid represented by the general formula (2) is in the range of 1: 1 to 1: 9 by mass ratio. The proton-conducting electrolyte according to claim 2, wherein   A fuel cell comprising a pair of electrodes and an electrolyte membrane disposed between the electrodes, wherein the electrolyte membrane comprises the proton conductive electrolyte according to any one of claims 1 to 3. . 5. The fuel cell according to claim 4, wherein the proton-conducting electrolyte according to claim 1 is contained in a part of the electrode.

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