All-Printed Paper-Based Micro-supercapacitors Using Water-Based Additive-Free Oxidized Single-Walled Carbon Nanotube Pastes

Abstract

Printing technologies that integrate wearable components onto flexible and stretchable substrates are crucial for the development of miniaturized wearable electronics. In this study, we developed all-printed paper-based flexible micro-supercapacitors based on water-based additive-free oxidized single-walled carbon nanotube pastes. The use of a modified Brodie’s method with mild oxidants and minimum usage of strong acids enabled the production of highly conductive and printable oxidized single-walled carbon nanotube pastes. Pseudo-plastic pastes were obtained because of the numerous hydrogen bonds between the oxidized single-walled carbon nanotubes. By photothermal treatment with intense pulsed light irradiation, a microporous structure was developed in the interdigitated energy storage electrodes to facilitate the infiltration of electrolytes. The paper-based flexible micro-supercapacitor exhibited a high energy density of 0.51 μW h cm–2 at a power density of 0.59 mW cm–2 and a superior capacity retention of 85% after 10,000 bending cycles with a bending radius of 3 mm. The all-printed flexible micro-supercapacitor array with a total capacitance of 0.1 mF charged to 4.0 V successfully powered a commercial digital clock for approximately 40 s. The micro-supercapacitor array operated properly under both tensile and compressive strains. These results demonstrate that the water-based additive-free oxidized single-walled carbon nanotube pastes are promising printable materials for the construction of flexible micro-supercapacitors.