Design and Synthesis of MnO₂/Mn/MnO₂ Sandwich-Structured Nanotube Arrays with High Supercapacitive Performance for Electrochemical Energy Storage

Abstract

We demonstrate the design and fabrication of novel nanoarchitectures of MnO(2)/Mn/MnO(2) sandwich-like nanotube arrays for supercapacitors. The crystalline metal Mn layers in the MnO(2)/Mn/MnO(2) sandwich-like nanotubes uniquely serve as highly conductive cores to support the redox active two-double MnO(2) shells with a highly electrolytic accessible surface area and provide reliable electrical connections to MnO(2) shells. The maximum specific capacitances of 937 F/g at a scan rate of 5 mV/s by cyclic voltammetry (CV) and 955 F/g at a current density of 1.5 A/g by chronopotentiometry were achieved for the MnO(2)/Mn/MnO(2) sandwich-like nanotube arrays in solution of 1.0 M Na(2)SO(4). The hybrid MnO(2)/Mn/MnO(2) sandwich-like nanotube arrays exhibited an excellent rate capability with a high specific energy of 45 Wh/kg and specific power of 23 kW/kg and excellent long-term cycling stability (less 5% loss of the maximum specific capacitance after 3000 cycles). The high specific capacitance and charge-discharge rates offered by such MnO(2)/Mn/MnO(2) sandwich-like nanotube arrays make them promising candidates for supercapacitor electrodes, combining high-energy densities with high levels of power delivery.

Engineering three-dimensional hybrid supercapacitors and microsupercapacitors for high-performance integrated energy storage

“…Nevertheless, the thickness and the area-normalized capacitance of these electrodes are not adequate for most applications. A promising approach to realize practical applications of MnO 2 is to incorporate nanostructured MnO 2 on highly conductive support materials with high surface areas such as nickel nanocones (13), Mn nanotubes (14), activated carbon (15), carbon fabric (16), conducting polymers (17), carbon nanotubes (18,19), and graphene (20)(21)(22)(23)(24). Although promising…”

pH‐Regulated Synthesis of Multi‐Shelled Manganese Oxide Hollow Microspheres as Supercapacitor Electrodes Using Carbonaceous Microspheres as Templates

“…The specific capacitance of the electrodes with different scan rates is given in Figure 4b. Specific capacitance of the electrode was calculated by integrating the voltammetric charge in the CV curves 18. At the same scan rate, the resulting specific capacitance for the multi‐shelled Mn 2 O 3 hollow microspheres electrodes were much higher than that of the Mn 2 O 3 NPs, and among them triple‐shelled Mn 2 O 3 hollow microspheres achieved a maximum capacitance, the crest value of specific capacitance of 1640 F g –1 at the scan rate of 5 mV s –1 can be achieved with the triple‐shelled Mn 2 O 3 hollow microspheres.…”

A Review of Metal Oxide Composite Electrode Materials for Electrochemical Capacitors

“…It is suggested that the unique architectures of the highly conductive Mn layer and the double hallow nanostructured MnO 2 have provided large surface area and short ion di®u-sion path that contribute to the high capacitive performance. 85 On top of their poor electronic conductivity, the electrochemical cyclability is another important issue for MnO 2 electrodes. 52 Zhang et al achieved promising result from MnO 2 /PANI composites with the maximum speci¯c capacitance of 320 F/g compared to that of pure MnO 2 (125 F/g).…”