Catalyst Free MnO 2 Nanoflakes for Electrochemical Capacitor

Abstract

This paper reports an efficient method for growing MnO 2 nanoflakes by reactive magnetron sputtering for supercapacitor applications. The physical vapor deposition technique presented in this work is simple, unique, without much chemical usage, direct and economically viable route for growing nanoflakes as per the requirement for different applications. Here, MnO 2 nanoflakes were directly deposited on the steel cold finger substrate at liquid nitrogen temperature. The MnO 2 nanoflakes electrode based supercapacitor cell in three electrode configuration delivers good specific capacitance value ∼374 F g −1 at current density of 1.1 Ag −1 in 1M sodium sulphate (Na 2 SO 4 ) aqueous electrolyte solution. The symmetric two electrode supercapacitor cell delivers a high capacitance value ∼64 Fg −1 at 1.17 Ag −1 , good cycling ability, 85.59% of capacitance retention after 1500 cycles along with good energy and power density, 7.2 Wh kg −1 and 607 Wkg −1 respectively. This work opens a new avenue towards efficient designing of catalyst-free MnO 2 nanoflakes.