Joule Heating-Induced Carbon Fibers for Flexible Fiber Supercapacitor Electrodes

Jin Gu Kang, Gang Wang, Sung-Kon Kim

Research output: Contribution to journalArticlepeer-review


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° 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.
Original languageEnglish (US)
Article number5255
Pages (from-to)1-10
Number of pages10
Issue number22
StatePublished - Nov 2 2020


  • supercapacitor
  • wearable device
  • energy storage
  • Joule heating
  • fiber electrode
  • Wearable device
  • Supercapacitor
  • Fiber electrode
  • Energy storage

ASJC Scopus subject areas

  • Materials Science(all)


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