Highly Flexible Environmentally Friendly Printed Supercapacitors

Abstract

In this study, we propose a highly flexible environmentally friendly supercapacitor suitable for low-power Internet-of- Everything applications and the effect of bending (both static and cyclic) on its electrical performance. The supercapacitors are all comprised of carbon electrodes (activated carbon (AC) on a graphite current collector) printed on a flexible plastic substrate, with a NaCl (aq) electrolyte. The capacitance of all the devices is on the order of 0.3 F. Two different substrates (A1 coated PET and PP/PA/EVOH/PA/PE [PP-PE]) as well as two different top-bottom substrate sealing methods (heat sealing, adhesive film) were investigated, with the PP-PE substrate and adhesive film sealing found to be preferable. However, all supercapacitors exhibited a rather high tolerance for bending down to a 1.25 cm radius. Little effect on bending reliability was found on the electrode fabrication process (roll-to-roll (R2R) vs. screen printing and manual stencil printing), however R2R printed devices have a higher uniformity of electrical properties. It was confirmed that, if the sealing method is resilient to bending, the degradation of the printed films are not the limiting factor in device flexibility.