Development of Poly (Vinyl Alcohol) (PVA)-Based Ion Conductors for Electric Double Layer Capacitors (EDLCS) Application

Wong, Jacky Ing Chiong (2019) Development of Poly (Vinyl Alcohol) (PVA)-Based Ion Conductors for Electric Double Layer Capacitors (EDLCS) Application. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The solid poly(vinyl alcohol) (PVA)−sodium acetate trihydrate (CH3COONa•3H2O) electrolytes had been prepared using solution casting method. The influence of incorporation of ionic liquid, 1−Butyl−3−Methylimidazolium Bromide (BmImBr) is studied throughout this research. The ionic conductivity of is increased five orders of magnitude from (1.07±0.03)×10−8 S cm−1 to (1.95±0.01)×10−3 S cm-1 with doping of 20 wt. % of BmImBr at ambient temperature. The BmImBr−based polymer electrolytes obey Vogel−Tamman−Fulcher (VTF) theory which is related to free volume model. The addition of BmImBr reduces the glass transition temperature (Tg) of the polymer electrolytes significantly as shown in differential scanning calorimetry (DSC) which is contributed by the plasticizing effect of the ionic liquid and improves the thermal stability of the polymer electrolytes as proven in thermogravimetric analysis (TGA). The complexation reactions between PVA, sodium acetate trihydrate, and BmImBr is proven in Fourier Transform Infrared (FTIR) studies. The addition of BmImBr widens the electrochemical potential window of the polymer electrolytes as shown in linear sweep voltammetry (LSV). Electric double layer capacitors (EDLCs) are fabricated using the most conducting BmImBr−based polymer electrolyte and carbon−based electrodes. The impregnation of ionic liquid into the polymer electrolyte improves the specific capacitance of fabricated EDLC in cyclic voltammetry (CV) and exhibits good electrochemical stability as proven in galvanostatic charge−discharge (GCD) performances.