Polymer electrolyte composition, polymer electrolyte membrane, membrane electrode assembly and solid polymer electrolyte-based fuel cell

A process for producing a polymer electrolyte membrane, comprising the steps of:

• dissolving or suspending a polymer electrolyte (A component) having an ion exchange capacity of from 0.5 to 3.0 meq/g, a compound (B component) having a thioether group and a compound (C component) having an azole ring in one or more protic solvents to obtain a polymer electrolyte composition in which a mass ratio (B/C) of the B component to the C component is from 1/99 to 99/1 and a total of the content of the B component and the C component is from 0.01 to 50% by mass based on the solid content in the polymer electrolyte composition;
• casting the polymer electrolyte composition;
• and
• removing the solvents to form a membrane.

An electrode catalyst layer produced from an electrode catalyst composition comprising:

• a composite particle in which an electrode catalyst particle is supported on a conductive particle and
• a polymer electrolyte composition comprising:
• a polymer electrolyte (A component) having an ion exchange capacity of from 0.5 to 3.0 meq/g,
• a compound (B component) having a thioether group and
• a compound (C component) having an azole ring,
• wherein a content of the composite particle in the electrode catalyst layer is 20 to 95% by mass based on the electrode catalyst layer,
• a mass ratio (B/C) of the B component to the C component is 1/99 to 99/1, and
• a total content of the B component and the C component is 0.01 to 50% by mass based on the solid content in the polymer electrolyte composition.

A process for producing an electrode catalyst layer, comprising the steps of:

• dissolving or suspending a polymer electrolyte (A component) having an ion exchange capacity of from 0.5 to 3.0 meq/g, a compound (B component) having a thioether group and a compound (C component) having an azole ring in one or more protic solvents to obtain a polymer electrolyte composition in which a mass ratio (B/C) of the B component to the C component is 1/99 to 99/1 and a total content of the B component and the C component is 0.01 to 50% by mass based on the solid content in the polymer electrolyte composition;
• preparing an electrode catalyst composition in which a composite particle where an electrode catalyst particle is supported on a conductive particle is dispersed in the polymer electrolyte composition at a ratio of from 1 to 100% by mass based on the polymer electrolyte composition;
• and
• drying and solidifying the electrode catalyst composition.