Gas diffusion layer for fuel cells, having improved bending properties

A method for producing a gas diffusion layer for a fuel cell, comprising a flat electrically conductive material, the method comprising:

• i) providing at least one fiber material selected from the group consisting of carbon fiber nonwoven fabrics, carbon fiber woven fabrics, and combinations thereof;
• ii) coating and/or impregnating the at least one fiber material provided in step i) with a composition comprising at least one fluorine-containing polymer and at least one polymer different from the at least one fluorine-containing polymer and selected from the group consisting of polyetherketones, polyphenylene sulfides, polysulfones, polyethersulfones, partially aromatic (co) polyamides, polyimides, polyamide-imides, polyether-imides and combinations thereof;
• and
• iii) subjecting the coated and/or impregnated at least one fiber material to a thermal treatment.

A fuel cell having at least one gas diffusion layer, comprising:

• A) a flat electrically conductive material, including:
• a) at least one fiber material selected from the group consisting of carbon fiber nonwoven fabrics, carbon fiber woven fabrics, and a combination thereof, wherein the at least one fiber material includes:
• b1) at least one fluorine-containing polymer, and
• b2) at least one polymer different from b1), selected from the group consisting of polyaryletherketones, polyphenylene sulfides, polysulfones, polyethersulfones, partially aromatic (co) polyamides, polyimides, polyamide-imides, polyether-imides and combinations thereof,
• wherein b1) and b2) are applied to the at least one fiber material and/or incorporated therein;
• and/or:
• B) a sintered product of the flat electrically conductive material,
• wherein the flat electrically conductive material or the sintered product of the flat electrically conductive material has at least one of the following properties:
• a bending stiffness, determined by loading at midspan in a 3-point bending flexural test according to DIN EN ISO 178:2019-08 on a 50 mm wide, 0.13 mm thick and 100 mm long rectangular test specimen at a support span of 32 mm and a test speed of 2 mm/min,
• from 0.05 to 0.08 N/mm,
• a maximum bending angle α, determined by loading at midspan in a 3-point bending flexural test according to DIN EN ISO 178:2019-08 on a 50 mm wide, 0.13 mm thick and 100 mm long rectangular test specimen at a support span of 32 mm and a test speed of 2 mm/min, from 50 to 60°, and/or
• a flexural modulus, determined by loading at midspan in a 3-point bending flexural test according to DIN EN ISO 178:2019-08 on a 50 mm wide, 0.13 mm thick and 100 mm long rectangular test specimen at a support span of 32 mm and a test speed of 2 mm/min, from 3000 to 6000 N/mm2.