Interconnected network of MnO2 nanowires with a "cocoonlike" morphology: Redox couple-mediated performance enhancement in symmetric aqueous supercapacitor

Sandipan Maiti, Atin Pramanik, Sourindra Mahanty

Research output: Contribution to journalArticlepeer-review

147 Scopus citations

Abstract

Low electronic conductivity and slow faradic processes limit the performance of MnO2 as an electrochemical pseudocapacitor with respect to cycling and power density. Herein, we report preparation of single-phase α-MnO2, composed of an interconnected nanowire network with "cocoonlike" morphology, and its application as electrode in a symmetric aqueous supercapacitor. Increased "effective" surface area, coexistence of micropores and mesopores, and enhanced electron transport in these nanowire networks result in a specific pseudocapacitance (C S) of 775 F·g-1 in 3 M KOH, derived from cyclic voltammetry in the potential window of -1 to +1 V at a scan rate of 2 mV·s-1, the highest reported for two-electrode symmetric configuration. Furthermore, introduction of K4Fe(CN)6 as a redox-Active additive to KOH results in ∼7 times increase in energy density at a power density of ∼6000 W·kg-1. The presence of the Fe(CN)64-/Fe(CN)63- redox couple provides an electron buffer source compensating for the slow faradic reactions. The results demonstrate that this simple approach might be an effective way to enhance the redox kinetics and reversibility of transition metal oxide-based pseudocapacitors.

Original languageEnglish
Pages (from-to)10754-10762
Number of pages9
JournalACS applied materials & interfaces
Volume6
Issue number13
DOIs
StatePublished - 9 Jul 2014
Externally publishedYes

Keywords

  • electrochemical pseudocapacitor
  • energy storage
  • hydrothermal synthesis

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