A rollable ultra-light polymer electrolyte membrane fuel cell

We have developed a highly flexible, ultra-light and thin polymer electrolyte membrane fuel cell that can be used as a portable power source for flexible electronics. To achieve such flexibility and ultra-lightness, we fabricated a thin flow-field plate using a thermal imprinting process and combined it with a laser-machined metal current collector. The air-breathing fuel cell, with a thickness of 0.992 mm and a weight of 2.23 g, demonstrated a total power of 508 mW and a performance degradation of <10% after severe bending fatigue (200 repeated bends). This high power per weight (0.228 W g(-1)) and robust bending durability have never been observed before. The highly flexible architecture enabled the operation of the fuel cell in an S-shape or even in a rolled-up state without any significant performance loss. We have fabricated a cylindrical planar stack of 10 fuel cells and successfully carried out its outdoor operation to demonstrate its practical applications in various fields.