J.S. Shaikh

An Mn Doped Polyaniline Electrode for Electrochemical Supercapacitor

Undoped and Mn doped Polyaniline (PANI) thin films were deposited on stainless steel substrates by sonochemical method. Films deposition was done using dip coating technique. To study the Mn doping effect on the specific capacitance of PANI, concentration of Mn was varied from 0.4 to 1.6 wt %. The Fourier Transform-IR (FT-IR) and Raman spectroscopy techniques have been used for the phase identification and determination of the Mn in the PANI films. Surface morphology was examined by using Field Emission Scanning Electron Microscopy (FESEM) which showed nanofiber aggregate structure of undoped PANI and porous and well distributed nanofibers for the doped PANI. The supercapacitive behavior of the electrodes was tested in three electrode system with 1.0 M H 2 SO 4 electrolyte by using cyclic voltammetry. The specific capacitance value increases from 285 to 474 F g ―1 as the Mn concentration was increased. This work demonstrates a simple strategy of improving specific capacitance of the polymer and hence may be adopted easily for other dopants also. Thus the work will open a new avenue for designing low cost high performance devices for better supercapcitors.

Symmetric supercapacitor: Sulphurized graphene and ionic liquid

Symmetric supercapacitor is advanced over simple supercapacitor device due to their stability over a large potential window and high energy density. Graphene is a desired candidate for supercapacitor application since it has a high surface area, good electronic conductivity and high electro chemical stability. There is a pragmatic use of ionic liquid electrolyte for supercapacitor due to its stability over a large potential window, good ionic conductivity and eco-friendly nature. For high performance supercapacitor, the interaction between ionic liquid electrolyte and graphene are crucial for better charge transportation. In respect of this, a three-dimensional (3D) nanoporous honeycomb shaped sulfur embedded graphene (S-graphene) has been synthesized by simple chemical method. Here, the fabrication of high performance symmetric supercapacitor is done by using S-graphene as an electrode and [BMIM-PF6] as an electrolyte. The particular architecture of S-graphene benefited to reduce the ion diffusion resistance, providing the large surface area for charge transportation and efficient charge storage. The S-graphene and ionic liquid-based symmetric supercapacitor device showed the large potential window of 3.2 V with high energy density 124 Wh kg-1 at 0.2 A g-1 constant applied current density. Furthermore, this device shows good cycling performance (stability) with a capacitive retention of 95% over 20,000 cycles at a higher current density of 2 A g-1.