Layer by Layer Ex-Situ Deposited Cobalt-Manganese Oxide as Composite Electrode Material for Electrochemical Capacitor.

Rusi Rusi,S R Majid,P Y Chan,Yogendra Kumar Mishra

doi:10.1371/journal.pone.0129780

Abstract

The composite metal oxide electrode films were fabricated using ex situ electrodeposition method with further heating treatment at 300°C. The obtained composite metal oxide film had a spherical structure with mass loading from 0.13 to 0.21 mg cm-2. The structure and elements of the composite was investigated using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). The electrochemical performance of different composite metal oxides was studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (CD). As an active electrode material for a supercapacitor, the Co-Mn composite electrode exhibits a specific capacitance of 285 Fg-1 at current density of 1.85 Ag-1 in 0.5M Na2SO4 electrolyte. The best composite electrode, Co-Mn electrode was then further studied in various electrolytes (i.e., 0.5M KOH and 0.5M KOH/0.04M K3Fe(CN) 6 electrolytes). The pseudocapacitive nature of the material of Co-Mn lead to a high specific capacitance of 2.2 x 103 Fg-1 and an energy density of 309 Whkg-1 in a 0.5MKOH/0.04MK3Fe(CN) 6 electrolyte at a current density of 10 Ag-1. The specific capacitance retention obtained 67% of its initial value after 750 cycles. The results indicate that the ex situ deposited composite metal oxide nanoparticles have promising potential in future practical applications.

Highlights

Electrochemical supercapacitors are appealing as devices for storing electrical energy, because they can deliver power at higher rates than batteries and higher energy density than conventional capacitors [1,2,3]
They can be classified by their charge storage mechanism (i.e., as electrical double layer capacitors (EDLC) and pseudocapacitors)
The contiguous particles are only observed in the FESEM images of Ni-Mn and NiCo-Mn, shown in Fig 1B and 1C, which tended to form large agglomerated particles

Summary

Introduction

Electrochemical supercapacitors are appealing as devices for storing electrical energy, because they can deliver power at higher rates than batteries and higher energy density than conventional capacitors [1,2,3]. They can be classified by their charge storage mechanism (i.e., as electrical double layer capacitors (EDLC) and pseudocapacitors). Pseudocapacitors are being developed in order to improve energy density through the storage mechanism of intercalation/deintercalation cations from the electrolyte into the electrode. A lot of materials have been studied as potential electrode materials for supercapacitors including (1)

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Conclusion