Novel in situ growing carbon nanocoils onto steel mesh as positive electrode and hexagonal-MoO3 micro-rod array onto carbon fabric as negative electrode for assembling dual-asymmetric supercapacitors with redox active gel eleectrolyte

Abstract

Intrinsically functionalized carbon nanocoils (CNCs) are in-situ grown onto the microwire surface of stainless steel mesh (SS) in an alcohol flame. The CNCs are deposited without using any additional catalysts and the flame growth mechanism is proposed. Such a unique structure with functionalized CNCs directly growing onto SS micro-wires in the mesh current collector makes it an excellent binder-free CNC/SS electrode. It exhibits ultrahigh capacitance in a iron ion based redox active electrolyte, where an remarkable areal capacitance of 4160 mF/cm 2 at 20 mA/cm 2 can be achieved. Meanwhile, hexagonal MoO 3 microrods are grown vertically onto carbon fibers and their electrochemical behaviors in normal H 2 SO 4 electrolyte are investigated. Finally, novel dual-asymmetric supercapacitors (DASCs) with the configuration of CNC/H 2 SO 4 +PVA + Fe 2+/3+ //H 2 SO 4 +PVA/h-MoO 3 are assembled. The device exhibits an excellent areal capacitance of 1502 mF/cm 2 at 3 mA/cm 2 , and a remarkable ultrahigh energy density of 252.4 μW h/cm 2 at the power energy of 1.6 mW/cm 2 as well. The research is expected to promote the development of SCs with high energy density through the design and assembly of all their main components, including the direct growth of active materials onto current collectors and the appropriate utilizing the redox active gel electrolyte. • A facile method for growing carbon nanocoils on stainless steel mesh was developed. • The flame catalytic growth mechanism of CNCs on stainless steel mesh was proposed. • Arrays of vertical h-MoO 3 hexagonal micro-rods was grown onto carbon fabric. • Novel dual-asymmetric supercapacitor with redox active gel electrolyte was assembled. • Remarkable capacitance of 1.5F/cm 2 and energy density of 252.4 μWh/cm 2 was realized.