Development of foldable air-breathing polymer electrolyte membrane fuel cells for power sources of next-generation flexible electronics

Most conventional flexible fuel cells have limitations as they operate within a bendable range and require external fuel supply systems. These limitations hinder their application in form factor-free mobile devices. In this study, we present a foldable air-breathing fuel cell that overcomes these limitations. The foldable fuel cell operates in flat, bent, and folded positions without the need for an external air supply system, thanks to its open cathodic structure. Performance evaluation and durability evaluation against repeated and sustained folding are conducted. The fuel cell exhibits a peak power density of 36.6 mW cm-2 in the folded position. After 300 cycles of repeated folding, performance is maintained with negligible degradation. After 24 h of sustained folding, there is a slight decrease in performance. Furthermore, the fuel cell operates an electronic motor in the folded position using hydrogen supplied by a portable cartridge, demonstrating its practicality and portability. These results confirm the promising potential of the foldable fuel cell as a power source for next-generation form factor-free portable devices.