Proton conductor, method for manufacturing proton conductor, and fuel cell

#The present application is based on Japanese Patent Applications No. 2012-93175 filed on Apr. 16, 2012, No. 2012-250557 filed on Nov. 14, 2012, and No. 2013-39574 filed on Feb. 28, 2013, the disclosure of which is incorporated herein by reference.

#The present disclosure relates to a proton conductor, a method for manufacturing the proton conductor, and a fuel cell using the proton conductor.

#Patent Literature 1: JP-2002-097272 A

#The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

#FIG. 1 is an explanatory drawing illustrating a manufacturing method of a single cell of a fuel cell according to an embodiment of the present disclosure;

#FIG. 2 is a perspective view illustrating a structure of a single cell of a fuel cell according to the embodiment of the present disclosure;

#An embodiment of the present disclosure will be explained. The oxoanion for use herein is exemplified by phosphate ion and sulfate ion. Among them, phosphate ion is preferred for satisfactory chemical stability to hydrogen. The phosphate ion may also be in the form of hydrogenphosphate ion to which one proton coordinates, or in the form of dihydrogenphosphate ion to which two protons coordinate. In a preferred embodiment, the oxoanion is present as a monomer without condensation and coordinates to the metal ion. This allows the proton conductor to hold protons in a high concentration and to exhibit satisfactory stability to water.

#The molecule capable of undergoing protonation or deprotonation for use herein is a molecule having a coordination site in a number of preferably two or more per molecule. Further, the molecule capable of undergoing protonation or deprotonation may be also simply referred to as a proton-coordinating molecule. The coordination site serves to coordinate to a proton. The molecule capable of undergoing protonation or deprotonation is preferably selected from imidazole, triazole, benzimidazole, benzotriazole, and derivatives of them. These are preferred for satisfactory ionic conductivity because of having a coordination site or sites with good balance between coordination and release of proton. As used herein the term “derivative” refers to a compound corresponding to an original compound, except for replacing part of the chemical structure of the original compound with another atom or atomic group. Exemplary derivatives for imidazole include 2-methylimidazole, 2-ethylimidazole, histamine, and histidine.

#The molecule capable of undergoing protonation or deprotonation is exemplified by: primary amines represented by General Formula R—NH2; secondary amines represented by General Formula R1(R2)—NH; and tertiary amines represented by General Formula R1(R2)(R3)—N. In these formulae, R, R1, R2, and R3 are each independently any of alkyl groups, aryl groups, alicyclic hydrocarbon groups, and heterocyclic groups.