Electrolyte membrane with anisotopic swelling and aligned filler
An electrolyte membrane ( 11 ) includes: a filler ( 20 ); and a polymer electrolyte ( 22 ). A thickness of the electrolyte membrane ( 11 ) is 1 micrometer to 500 micrometer, a moisture content thereof is 10 mass % or more, and a ratio of a swelling ratio in a membrane surface direction (xy) thereof and a swelling ratio in a membrane thickness direction (z) thereof satisfies following Expression 1: where Lambda z is the swelling ratio in the membrane thickness direction (z), and Lambda xy is the swelling ratio in the membrane surface direction (xy). λ xy λ z < 0.3 [ Math . 1 ]
1. An electrolyte membrane, comprising:
a membrane body comprising: a filler; and a polymer electrolyte,
wherein a thickness of the membrane body is 1 micrometer to 500 micrometer, a moisture content of the membrane body is 10 mass % or more, and a swelling anisotropy of a swelling ratio in a membrane surface direction of the membrane body to a swelling ratio in a membrane thickness direction of the membrane body satisfies an equation having the form:
λ
xy
λ
z
<
0.3
where Lambda z is the swelling ratio in the membrane thickness direction, and Lambda xy is the swelling ratio in the membrane surface direction, and
wherein an angle made by a center axis in a longitudinal direction of the filler and a surface parallel to the membrane surface direction is within 45 degrees.
2. An electrolyte membrane according to claim 1 , wherein an aspect ratio of the filler is 10 to 1000.
3. An electrolyte membrane according to claim 1 , wherein a content of the filler is 1 mass % to 90 mass % with respect to a total mass of the filler and the polymer electrolyte.
4. An electrolyte membrane according to claim 1 , wherein the filler is oriented in the surface direction of the membrane body.
5. An electrolyte membrane according to claim 1 , wherein the filler is subjected to surface treatment by an acid.
6. An electrolyte membrane according to claim 1 , wherein a constituent material of the filler is at least one selected from the group consisting of titania, potassium titanate, silica, silica-alumina, zirconia, and boehmite.
7. A membrane electrode assembly, comprising:
an electrolyte membrane according to claim 1 ;
an anode catalyst layer and an anode gas diffusion layer, which are arranged on one surface of the electrolyte membrane; and
a cathode catalyst layer and a cathode gas diffusion layer, which are arranged on the other surface of the electrolyte membrane.
8. A fuel cell, comprising:
a membrane electrode assembly according to claim 7 .
9. An electrolyte membrane according to claim 1 , wherein an aspect ratio of the filler is 10 to 500.
10. An electrolyte membrane according to claim 1 , wherein an aspect ratio of the filler is 10 to 150.
11. An electrolyte membrane according to claim 1 , wherein the angle is within 30 degrees.
12. An electrolyte membrane according to claim 1 , wherein an average diameter of the filler is 0.001 micrometer to 10 micrometer.