Kang, Jin Gu Wang, Gang Kim, Sung-Kon 2024-01-19T16:30:32Z 2024-01-19T16:30:32Z 2021-09-02 2020-11 1996-1944 https://pubs.kist.re.kr/handle/201004/117945 Microscale fiber-based supercapacitors have become increasingly important for the needs of flexible, wearable, and lightweight portable electronics. Fiber electrodes without pre-existing cores enable a wider selection of materials and geometries than is possible through core-containing electrodes. The carbonization of fibrous precursors using an electrically driven route, different from a conventional high-temperature process, is particularly promising for achieving this structure. Here, we present a facile and low-cost process for producing high-performance microfiber supercapacitor electrodes based on carbonaceous materials without cores. Fibrous carbon nanotubes-agarose composite hydrogels, formed by an extrusion process, are converted to a composite fiber consisting of carbon nanotubes (CNTs) surrounded by an amorphous carbon (aC) matrix via Joule heating. When assembled into symmetrical two-electrode cells, the composite fiber (aC-CNTs) supercapacitor electrodes deliver a volumetric capacitance of 5.1 F cm(-3) even at a high current density of 118 mA cm(-3). Based on electrochemical impedance spectroscopy analysis, it is revealed that high electrochemical properties are attributed to fast response kinetics with a characteristic time constant of 2.5 s. The aC-CNTs fiber electrodes exhibit a 94% capacitance retention at 14 mA cm(-3) for at least 10,000 charge-discharge cycles even when deformed (90 degrees bend), which is essentially the same as that (96%) when not deformed. The aC-CNTs fiber electrodes also demonstrate excellent storage performance under mechanical deformation-for example, 1000 bending-straightening cycles. English MDPI MICRO-SUPERCAPACITOR CARBONIZATION FABRICATION SPECTROSCOPY POLYPYRROLE CAPACITANCE STORAGE Joule Heating-Induced Carbon Fibers for Flexible Fiber Supercapacitor Electrodes Article 10.3390/ma13225255 1 MATERIALS, v.13, no.22 MATERIALS 13 22 scie scopus 000594204100001 2-s2.0-85096426129 Chemistry, Physical Materials Science, Multidisciplinary Metallurgy & Metallurgical Engineering Physics, Applied Physics, Condensed Matter Chemistry Materials Science Metallurgy & Metallurgical Engineering Physics Article MICRO-SUPERCAPACITOR CARBONIZATION FABRICATION SPECTROSCOPY POLYPYRROLE CAPACITANCE STORAGE supercapacitor fiber electrode Joule heating energy storage wearable device