Texas Tech University, Lubbock, TX, US
Large-capacitance and ultrahigh-rate electrochemical supercapacitors (UECs) with frequency response up to kilohertz (kHz) range are reported using light, thin, and flexible freestanding electrodes. The electrode is formed by perpendicularly edge oriented multilayer graphene/thin-graphite (EOG) sheets grown radially around individual fibers in carbonized cellulous paper (CCP), with cellulous carbonization and EOG deposition implemented in one step. The resulted ∼10 μm thick EOG/CCP electrode is light and flexible. The oriented porous structure of EOG with large surface area, in conjunction with high conductivity of the electrode, ensures ultrahigh-rate performance of the fabricated cells, with large areal capacitance of 0.59 mF cm−2 and 0.53 mF cm−2 and large phase angle of −83° and −80° at 120 Hz and 1 kHz, respectively. Particularly, the hierarchical EOG/CCP sheet structure allows multiple sheets stacked together for thick electrodes with almost linearly increased areal capacitance while maintaining the volumetric capacitance nearly no degradation, a critical merit for developing practical faraday-scale UECs. 3-layers of EOG/CCP electrode achieved an areal capacitance of 1.5 mF cm−2 and 1.4 mF cm−2 at 120 Hz and 1 kHz, respectively. This demonstration moves a step closer to the goal of bridging the frequency/capacitance gap between supercapacitors and electrolytic capacitors.
Primary Application Area: Energy, Efficiency, Resilience
Technology Development Status: Concept
Technology Readiness Level: TRL 3
Vetted Programs/Awards: The technology has completed a Regional and National NSF I-corps program.
Organization Type: Academic/Gov Lab
Showcase Booth #: 530
GOVT/EXTERNAL FUNDING SOURCES
External Funding to Date: State grant of $50,000.