Attachable micropseudocapacitors using highly swollen laser-induced-graphene electrodes

• Main Authors: Lee, Yeong A., Lim, Joel, Cho, Younghyun, Lee, Hyub, Park, Sangbaek, Lee, Go-Woon, Yoo, Chung-Yul, Park, Sang Hyun, Murukeshan, Vadakke Matham, Kim, Seungchul, Kim, Young-Jin, Yoon, Hana
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering; Microsupercapacitor; Laser Direct Writing
• Online Access: https://hdl.handle.net/10356/146270
• Institution: Nanyang Technological University

For powering wearable electronics, extensive research has been directed toward microscale flexible and stretchable energy-storage devices. Microsupercapacitors, though promising candidates, remain limited in terms of design flexibility, scalability, reusability, and compatibility with general substrates. This paper reports a high-performance sticker-type flexible microsupercapacitor using highly swollen reduced-graphene-oxide electrodes fabricated by an ultrashort-pulse laser to promote full active-site and durability of the electrodes. Our sticker-type flexible micropseudocapacitor provides a comparable volumetric energy density of 1.08 mWh cm−3 and 13 times higher volumetric power density of 83.5 mW cm−3 compared to conventional lithium thin-film batteries. Bio-inspired surface modifications are additionally applied to the reduced-graphene-oxide electrodes, which provides a six-fold increase (10.38 mF cm−2) of the areal capacitance. A 6 × 2 micropseudocapacitor array embedded in a sub-millimeter thin PDMS film adheres to safety goggles and successfully powers a μ-LED. The total capacitance of the array is maintained at ~97% of its original value after 200 repetitive attachments and detachments showing good durability. In addition, the sticker-type micropseudocapacitor array shows a stable performance under repeated deformation, and up to ~99% of capacitance retention after 200 bending cycles. This novel re-attachable flexible micropseudocapacitor will expedite the widespread use of flexible and wearable devices.