A rollable ultra-light polymer electrolyte membrane fuel cell

The capability of fabricating lightweight, small and flexible power sources is a key to cope with the increasing demand for smart and ubiquitous energy sources for current and future flexible electronics. We herein report a portable, lightweight and rollable polymer electrolyte membrane fuel cell. Because of its highly thin and flexible design, the device exhibited excellent durability against repetitive bending and easily deformed to any desired shape such as rolled-up or S-shape geometries. In addition, we introduced a portable flexible planar stack that demonstrates real practical applications of these devices.