This experimental study, reports the use of flexible tape casting of dense carbon nanofiber (CNFs) alone and in hybrid structure with MnO₂ for supercapacitor applications. Different electrolyte concentrations of potassium hydroxide (KOH) were tested and it was founded that mild concentrated electrolyte, like 9 M KOH, provides higher specific capacitance 38 F g⁻¹ at a scan rate of 5 mV s⁻¹. Electrochemical impedance spectroscopy (EIS) measurements explain that the solution resistance and the charge transfer resistance is higher for 3 M KOH concentrations and lower for 6 M KOH concentrations. Afterwards a novel, fast and simple method is adopted to achieve a hybrid nanostructure of CNFs/MnO₂ with various KMnO₄ ratios. The hybrid supercapacitor, having loaded a mass of 0.0003 g MnO₂ as a thin film, delivers a highest specific capacitance of 812 F g⁻¹ at a scan rate 5 mV s⁻¹. Charge/discharge cycling stability at current density of 7.9 A g⁻¹ demonstrates larger specific capacitance 303 F g⁻¹ and stability. Furthermore, the hybrid supercapacitor can deliver specific energy (72.4 Wh kg⁻¹) at specific power (3.44 kW kg⁻¹). Specific surface area increase from 68 m² g⁻¹ for CNFs to 240 m² g⁻¹ for CNFs/MnO₂.

Title

Materials Research Express

Publisher

IOP Publishing

Publisher Country

Canada

Indexing

Thomson Reuters

Impact Factor

1.449

Publication Type

Both (Printed and Online)

Volume

4

Year

2017

Pages

025007