Graduation Year

2013

Document Type

Thesis

Degree

M.S.E.E.

Degree Granting Department

Electrical Engineering

Major Professor

Manoj K. Ram

Co-Major Professor

Arash Takshi

Keywords

conducting polymer, dielectric constant, electrochemical, Langmuir Blodgett, leakage current, Polymer materials

Abstract

Supercapacitors are well known for their improvised power density compared to batteries. Ongoing research is mainly focused on improving the energy density of supercapacitors by using different electrode material nanocomposites. The recent research has revealed that graphene (G)-polyaniline (PANI) nanocomposite could be a promising material for supercapacitor applications. The supercapacitor is also associated with self-leakage current regardless of any electrode material. The main objectives of the project are to: (i) synthesize highly fabricate supercapacitor based of G-PANI electrode; (ii) improve the energy density of supercapacitor by applying ultrathin monolayer/monolayers film electrode surface. It is crucial to either improve or retain the effective capacitance of the dielectric film. The dielectric material chosen is polyvinylidene fluoride (PVDF) due to its dielectric constant and electrochemical properties. Langmuir-Schaefer (LS) technique is used to deposit the PVDF film onto the substrate. The optical properties of electrode materials were measured by UV-vis spectrophotometer. The surface morphology of the fabricated electrode material has been investigated using scanning electron microscopic (SEM) and atomic force microscopic (AFM) studies. The supercapacitor with and without dielectric layer have been studied using cyclic voltammetry, charging and discharging, and electrochemical impedance techniques, respectively. The specific capacitance has been found to increase by application of one monolayer of PVDF film of G-PANI electrode. However, the LS film of PVDF does not show the minimization of leakage current but revealed an increase in the specific capacitance due to enhancement in surface area associated with the electrode besides PVDF is also an electrochemical active material. The electrochemical investigation of various layers of PVDF on G-PANI in symmetric and asymmetric supercapacitor configuration has been presented in thesis. The future scope of the project could be designing the electrode with various number of layers of dielectric material that could reduce the leakage current, and retaining the specific capacitance of G-PANI nanocomposite electrodes.

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