# Electrochemical Supercapacitor Studies of Nanostructured $\alpha-MnO_2$ Synthesized by Microemulsion Method and the Effect of Annealing

Devaraj, S and Munichandraiah, N (2007) Electrochemical Supercapacitor Studies of Nanostructured $\alpha-MnO_2$ Synthesized by Microemulsion Method and the Effect of Annealing. In: Journal of The Electrochemical Society, 154 (2). A80-A88.

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## Abstract

Nanometer-scale particles of $MnO_2$ have been synthesized by microemulsion route for electrochemical supercapacitor studies. The $MnO_2$ has been found to be in \alpha-cyrstallographic form with tetragonal unit cell. Particles in the spherical/hexagonal shape with about 50 nm size have been observed in scanning electron microscopy and transmission electron microscopy studies. Cyclic voltammograms have exhibited rectangular shape between 0 and 1.0 V vs saturated calomel electrode at sweep rates up to $100 mV s^{-1}$ due to nanoparticles of $MnO_2$. From galvanostatic charge-discharge studies, specific capacitance of $297 F g^{-1}$ has been obtained, which is greater than about $240 Fg^{-1}$ usually reported for this material. The $\alpha-MnO_2$ samples have been annealed at several temperatures, and nanoparticles (10–90 nm) and nanorods (5 nm diameter) of varying dimensions have been obtained. The effect of annealing at different temperatures on crystallographic nature and electrochemical properties are reported.

Item Type: Journal Article Copyright of this article belongs to the Electrochemical Society Division of Chemical Sciences > Inorganic & Physical Chemistry 13 Mar 2007 19 Sep 2010 04:34 http://eprints.iisc.ernet.in/id/eprint/9722