Nano-RuO2 -Decorated Holey Graphene Composite Fibers for Micro-Supercapacitors with Ultrahigh Energy Density

Shengli Zhai; Chaojun Wang; Huseyin Enis Karahan; Yanqing Wang; Xuncai Chen; Xiao Sui; Qianwei Huang; Xiaozhou Liao; Xin Wang; Yuan Chen

doi:10.1002/smll.201800582

Nano-RuO₂ -Decorated Holey Graphene Composite Fibers for Micro-Supercapacitors with Ultrahigh Energy Density

Small. 2018 Jun 7:e1800582. doi: 10.1002/smll.201800582. Online ahead of print.

Authors

Shengli Zhai^{1

2}, Chaojun Wang¹, Huseyin Enis Karahan², Yanqing Wang³, Xuncai Chen¹, Xiao Sui¹, Qianwei Huang⁴, Xiaozhou Liao⁴, Xin Wang², Yuan Chen¹

Affiliations

¹ School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, New South Wales, 2006, Australia.
² School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459, Singapore.
³ Faculty of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0032, Japan.
⁴ School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales, 2006, Australia.

PMID: 29882370
DOI: 10.1002/smll.201800582

Abstract

Compactness and versatility of fiber-based micro-supercapacitors (FMSCs) make them promising for emerging wearable electronic devices as energy storage solutions. But, increasing the energy storage capacity of microscale fiber electrodes, while retaining their high power density, remains a significant challenge. Here, this issue is addressed by incorporating ultrahigh mass loading of ruthenium oxide (RuO₂ ) nanoparticles (up to 42.5 wt%) uniformly on nanocarbon-based microfibers composed largely of holey reduced graphene oxide (HrGO) with a lower amount of single-walled carbon nanotubes as nanospacers. This facile approach involes (1) space-confined hydrothermal assembly of highly porous but 3D interconnected carbon structure, (2) impregnating wet carbon structures with aqueous Ru³⁺ ions, and (3) anchoring RuO₂ nanoparticles on HrGO surfaces. Solid-state FMSCs assembled using those fibers demonstrate a specific volumetric capacitance of 199 F cm^-3 at 2 mV s^-1 . Fabricated FMSCs also deliver an ultrahigh energy density of 27.3 mWh cm^-3 , the highest among those reported for FMSCs to date. Furthermore, integrating 20 pieces of FMSCs with two commercial flexible solar cells as a self-powering energy system, a light-emitting diode panel can be lit up stably. The current work highlights the excellent potential of nano-RuO₂ -decorated HrGO composite fibers for constructing micro-supercapacitors with high energy density for wearable electronic devices.

Keywords: carbon nanotubes; holey graphene; microfibers; ruthenium oxide; supercapacitors.