Controllable Template-Assisted Electrodeposition of Single- and Multi-Walled Nanotube Arrays for Electrochemical Energy Storage

Abstract

Here we explored a novel ZnO nanorod array template-assisted electrodeposition route to synthesize large-scale single-walled polypyrrole (PPy) nanotube arrays (NTAs) and multi-walled MnO2/PPy/MnO2 NTAs. The structures of nanotubes, such as external and inner diameters, wall thicknesses, and lengths, can be well controlled by adjusting the diameters and lengths of ZnO nanorods and deposition time. The synthesized hybrid MnO2/PPy/MnO2 triple-walled nanotube arrays (TNTAs) as electrodes showed high supercapacitive perporties, excellent long-term cycling stability, and high energy and power densities. The PPy layers in MnO2/PPy/MnO2 TNTAs provide reliable electrical connections to MnO2 shells and uniquely serve as highly conductive cores to support the redox reactions in the active two-double MnO2 shells with highly electrolytic accessible surface area. The fabricated multi-walled NTAs allow high efficient utilization of electrode materials with facilitated transports of ions and electrons. The outstanding performance makes MnO2/PPy/MnO2 TNTAs promising candidates for supercapacitor electrodes.

Super-high rate stretchable polypyrrole-based supercapacitors with excellent cycling stability

“…This is confirmed by the well-defined rectangular shapes of most CVs and the wider working potential windows (Fig. S1) than those in most literatures [36,40,41,[47][48][49][50][51][52]. Fig.…”

“…These are believed that a thinner PPy facilitates electron transportation and ion accessibility, which maximizes the utilization of the PPy. The specific capacitances obtained in the fabricated solid-state devices are comparable, or even higher than many reported results with PPy as the electrode material tested in liquid electrolytes [36,40,41,[47][48][49][50][51]. It should be noted that we use the lower capacitances obtained from CVs for comparison with those in the literatures, instead of the higher numbers from CDs which are considered to be more accurate.…”

“…3a and b, the device can be operated at various scan rates up to 10 V/s and CVs keep the rectangular shape even at a high scan rate of 2 V/s. It should be noted that both numbers are 1-2 orders of magnitude higher than most scan rates for PPy electrodes measured even in aqueous electrolytes [36,40,41,[47][48][49][50][51][52], and are even equivalent to the highest values reported in solidstate the carbon nanotubes-MnO 2 devices, which also keep good rectangular shape at most scan rates [53]. These indicate the PPy-based solid-state supercapacitors fabricated can endure ultrafast voltage/current change rates, which is believed to be a result of effective electrochemical dynamic processes in the supercapacitors.…”

All graphene electrode for high‐performance asymmetric supercapacitor

“…18 Whereas, a hybrid supercapacitor (HSC) or asymmetric supercapacitor (ASC) is a system comprising of a battery or a pseudocapacitive material acting as one electrode material combined with electric bilayer capacitor (EDLC) electrode as counter electrode material, or in other words two dissimilar sort of electrodes operating via two diverse electrochemical procedures. 19 A major drawback, however, is the divergence of kinetics in two electrodes, which is yet to be overcome despite of recent advancements in ASCs. 19 A major drawback, however, is the divergence of kinetics in two electrodes, which is yet to be overcome despite of recent advancements in ASCs.…”

Cobalt monoxide-doped porous graphitic carbon microspheres for supercapacitor application

“…There is faradaic current across the supercapacitor cell during the reversal processes of charging and discharging, which not only increases the specific capacitance but also extends the operation voltage of the supercapacitor14. Thus, transition metal (such as ruthenium, manganese, vanadium, tin, iron, nickel and cobalt) oxides and hydroxides with pseudo-capacitive behaviour are of great interest for the application as electrode materials in pseudo-supercapacitors1516171819202122232425. Although in recent years, a large number of studies have been made with the development of both types of supercapacitors with both theoretical understanding and practical fabrication made, the main challenges are still the low energy density and poor overall performance, which have to be tackled in order to widen the applications of supercapacitors12326.…”