One-Dimensional Assembly of Conductive and Capacitive Metal Oxide Electrodes for High-Performance Asymmetric Supercapacitors

Abstract

A one-dimensional morphology comprising nanograins of two metal oxides, one with higher electrical conductivity (CuO) and the other with higher charge storability (CoO), is developed by electrospinning technique. The CuO-CoO nanocomposite nanowires thus formed show high specific capacitance, high rate capability, and high cycling stability compared to their single-component nanowire counterparts when used as a supercapacitor electrode. Practical symmetric (SSCs) and asymmetric (ASCs) supercapacitors are fabricated using commercial activated carbon, CuO, CoO, and CuO-CoO composite nanowires, and their properties are compared. A high energy density of ∼44 Wh kg at a power density of 14 kW kg is achieved in CuO-CoO ASCs employing aqueous alkaline electrolytes, enabling them to store high energy at a faster rate. The current methodology of hybrid nanowires of various functional materials could be applied to extend the performance limit of diverse electrical and electrochemical devices.

Hybrid Composite Based on Porous Cobalt‐Benzenetricarboxylic Acid Metal Organic Framework and Graphene Nanosheets as High Performance Supercapacitor Electrode

“…A straight line with good regression is obtained for CoBTC MOF/GNS (Figure (D)) which indicates that OH − ions are undergoing diffusion process during electrochemical reaction. The corresponding values of diffusion co‐efficient (D) were calculated by using Randle's Sevcik equation and are found to be 3.78 x 10 −4 and 176.03 x 10 −4 cm 2 .s −1 for CoBTC MOF and CoBTC MOF/GNS respectively. The higher value of D obtained in case of CoBTC MOF/GNS indicates increase in the speed of ion transport which can lead to quicker permeation of electrolyte ions through the electrode material resulting into its better electrochemical performance.…”

Pseudocapacitive Charge Storage in Thin Nanobelts

“…The NiO-Co 3 O 4 hybrid and NiCo 2 O 4 nanobelts as well as CuO-Co 3 O 4 hybrid, NiO, CuO, and Co 3 O 4 nanowires were prepared by electrospinning as reported before [18,19]. The hybrid materials were synthesized from an equal molar ratio of their component precursors and stoichiometric ratios were used for the synthesis of NiCo 2 O 4 .…”

TiO2 Nanoparticles Modified MoO3 Nanobelts as Electrode Materials with Superior Performances for Supercapacitors

“…The maximum specific capacitance is 141 F g −1 at 1 A g −1 discharge current, which is much higher than that of the pure MoO 3 electrode with 69 F g −1 and TiO 2 electrode with 21 F g −1 . But the rate capability of samples is not very good, which may be due to the transfer of ions and electrons in the electrolyte has not been greatly improved ,. Long cycle life is an important part to evaluate the electrochemical behavior of the TiO 2 /MoO 3 electrodes.…”

“…The results show that the resistance of TiO 2 /MoO 3 is lower than that of MoO 3 , however, there is little difference in impedance study between two samples. So the rate capability of MoO 3 /TiO 2 composite material has not been improved very well ,…”

“…Compared to batteries and conventional capacitors, supercapacitors have attracted more attention in electrochemical energy‐storage applications such as mobile electronic devices and hybrid electric vehicle, which due to their high‐power density, fast charge‐discharge rate and long cycle life . Supercapacitors usually can be classified as electrical double‐layer capacitors (EDLCs) and pseudocapacitors depending on the charge storage mechanisms . For EDLCs, the electrode materials include carbon‐active materials (such as porous carbon, carbon nanotubes and graphene) with high specific surface area, and transition metal carbides and nitrides (such as titanium carbide) .…”