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Aromatic hydrocarbon based proton exchange membrane and direct methanol fuel cell using same

a proton exchange membrane and hydrocarbon based technology, applied in the direction of fuel cell details, ion-exchangers, electrochemical generators, etc., can solve the problems of affecting the establishment of fuel cell techniques, affecting the performance of the cell as a whole, and excessively high membrane cost, so as to improve the energy density improve the efficiency of the fuel cell, and reduce the size of the fuel cell

Inactive Publication Date: 2012-03-01
TOYOBO CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The membrane enables efficient power generation with high-energy density and compact fuel cell design, maintaining performance even with high-concentration methanol solutions, while preventing methanol crossover and electrode peeling, thus ensuring long-term stability and efficiency.

Problems solved by technology

However, when the Nafion (registered trade name) membrane is used in a fuel cell wherein methanol is used as a fuel, there is remarkably caused a problem called a methanol crossover, which is a problem that methanol permeates into the Nafion (registered trade name) membrane to flow into the side of its air electrode.
Thus, there arises a problem that the performance thereof as a cell falls.
Furthermore, it is pointed out that an excessively high cost for the membrane hinders the establishment of fuel cell technique thereof.
Consequently, the energy density becomes low and further the fuel tank becomes large-sized.
Thus, this hinders the practical use.
In membranes having high methanol permeability, such as a perfluorocarbon sulfonic acid membrane, power generating performance is not easily exhibited unless a diluted methanol aqueous solution is used.
However, proton conductivity and methanol blocking property are in general properties incompatible with each other; thus, if the proton conductivity is made preferential, the methanol permeability becomes high so as to cause a fall in the power generation characteristic easily, and if the methanol blocking property is made preferential, the resistance of the membrane becomes high, thereby causing a fall in the power generation characteristic easily.
As a result, the power generation characteristic does not become sufficient.
However, in this case also, the methanol concentration used in the direct methanol fuel cell is small, so that the above-mentioned problem is not solved.

Method used

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  • Aromatic hydrocarbon based proton exchange membrane and direct methanol fuel cell using same
  • Aromatic hydrocarbon based proton exchange membrane and direct methanol fuel cell using same
  • Aromatic hydrocarbon based proton exchange membrane and direct methanol fuel cell using same

Examples

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examples

[0082] Working examples of the invention will be described hereinafter, but the invention is not limited to the examples.

examples 1 to 4

, and Comparative Examples 1 to 4

Evaluating Method / Measuring Method

[0083] The thickness of a proton exchange membrane was obtained by making a measurement using a micrometer (Mitutoyo Standard Micrometer 0-25 mm 0.01 mm). The proton exchange membrane was allowed to stand still in a measuring room wherein the room temperature and the humidity were controlled into 20° C. and 30±5 RH %, respectively, for 24 hours or more, and then the membrane was cut into a sample having a size of 5×5 cm. The thicknesses at 20 points therein were measured, and the average value thereof was defined as the film thickness.

[0084] The amount of acid-type functional groups present in an ion exchange membrane was measured as the ion exchange capacity (IEC). For sample preparation, a sample piece (5×5 cm) was first dried under the flow of nitrogen gas in an oven at 80° C. for 2 hours, and further the piece was allowed to stand still in a desiccator filled with silica gel for 30 minutes. Thereafter, the dry...

example 1

[0090] Prepared was a mixture of a disodium salt of 3,3′-disulfo-4,4′-dichlorodiphenylsulfone, 2,6-dichlorobenzonitrile, 4,4′-biphenol, and potassium carbonate to set the mol ratio therebetween into 1.00 / 5.62 / 6.62 / 7.62, and then 15 g of the mixture was weighed and put into a 100 mL four-necked flask, together with 3.50 g of a molecular sieve. Nitrogen was then caused to flow in the flask. NMP as a solvent was used. The solution was stirred at 155° C. for one hour, and then the reaction temperature was raised up to 190-200° C. The reaction was continued until the viscosity of the system was sufficiently raised (for about 4 hours). After the solution was naturally cooled, the molecular sieve, which precipitated, was removed, and a polymer was precipitated in a strand form in water. The resultant polymer was washed in boiled ultrapure water for 1 hour, and then dried. A 30% solution of the polymer in NMP was prepared. The polymer solution was cast into a thin film by casting, and dried...

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Abstract

A proton exchange membrane is obtained which can give an excellent power generation characteristic when the membrane is applied to, in particular, a fuel cell wherein high-concentration methanol is used as a fuel. In the aromatic hydrocarbon based proton exchange membrane of the invention, the ion exchange capacity is set into the range of 0.6 to 1.3 meq / g. Moreover, the area swelling rate for a 30% by mass methanol aqueous solution at 40° C. is set into the range of 2 to 30%. Preferably, a sulfonic acid group is bonded to an aromatic ring of the aromatic hydrocarbon based polymer contained in the aromatic hydrocarbon based proton exchange film. Preferably, the aromatic hydrocarbon based polymer is a polyarylene ether based polymer.

Description

TECHNICAL FIELD [0001] The present invention relates to an aromatic hydrocarbon based proton exchange membrane useful as a polymeric electrolyte membrane for a direct methanol fuel cell wherein a high-concentration methanol aqueous solution is used as a fuel, and a direct methanol fuel cell using the same. BACKGROUND ART [0002] Direct methanol fuel cells are solid polymer fuel cells wherein methanol is used as a fuel to generate electric power, and are expected to be used as power sources for notebook size personal computers, PDAs, cellular phones, and so on. Direct methanol fuel cells have, as their center, a structure called a membrane electrode assembly (MEA), wherein a pair of electrodes are jointed to both faces of a proton exchange membrane. A methanol aqueous solution is supplied to one of the electrodes, and an oxidizing gas such as air is supplied to the other, whereby the structure can be operated as a cell. As the concentration of the methanol aqueous solution is higher, ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H01M8/10C08J5/22
CPCC08J5/2256H01M8/0291H01M8/1011C08J2371/12H01M8/1032H01M2300/0082Y02E60/523H01M8/1025H01M8/0289Y02E60/50
Inventor YAMASHITA, MASAHIROSAKAGUCHI, YOSHIMITSUKITAMURA, KOTA
Owner TOYOBO CO LTD
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