1 research outputs found
Wrapping Aligned Carbon Nanotube Composite Sheets around Vanadium Nitride Nanowire Arrays for Asymmetric Coaxial Fiber-Shaped Supercapacitors with Ultrahigh Energy Density
The
emergence of fiber-shaped supercapacitors (FSSs) has led to a revolution
in portable and wearable electronic devices. However, obtaining high
energy density FSSs for practical applications is still a key challenge.
This article exhibits a facile and effective approach to directly
grow well-aligned three-dimensional vanadium nitride (VN) nanowire
arrays (NWAs) on carbon nanotube (CNT) fiber with an ultrahigh specific
capacitance of 715 mF/cm<sup>2</sup> in a three-electrode system.
Benefiting from their intriguing structural features, we successfully
fabricated a prototype asymmetric coaxial FSS (ACFSS) with a maximum
operating voltage of 1.8 V. From core to shell, this ACFSS consists
of a CNT fiber core coated with VN@C NWAs as the negative electrode,
Na<sub>2</sub>SO<sub>4</sub> polyÂ(vinyl alcohol) (PVA) as the solid
electrolyte, and MnO<sub>2</sub>/conducting polymer/CNT sheets as
the positive electrode. The novel coaxial architecture not only fully
enables utilization of the effective surface area and decreases the
contact resistance between the two electrodes but also, more importantly,
provides a short pathway for the ultrafast transport of axial electrons
and ions. The electrochemical results show that the optimized ACFSS
exhibits a remarkable specific capacitance of 213.5 mF/cm<sup>2</sup> and an exceptional energy density of 96.07 μWh/cm<sup>2</sup>, the highest areal capacitance and areal energy density yet reported
in FSSs. Furthermore, the device possesses excellent flexibility in
that its capacitance retention reaches 96.8% after bending 5000 times,
which further allows it to be woven into flexible electronic clothes
with conventional weaving techniques. Therefore, the asymmetric coaxial
architectural design allows new opportunities to fabricate high-performance
flexible FSSs for future portable and wearable electronic devices