Development of Poly (Vinylidene Fluoride) Ion Conductors EDLC Using Phase Inversion Technique

Loi, Angeline Zi Ying (2020) Development of Poly (Vinylidene Fluoride) Ion Conductors EDLC Using Phase Inversion Technique. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Solid poly(vinylidene fluoride) (PVDF)-magnesium triflate electrolytes had been prepared by both phase inversion and solution casting techniques. The effect of salt on polymer electrolytes had been examined phase inversion technique. Then, the comparison for both techniques had been carried out. The ionic conductivity of polymer electrolyte produced using solution casting method (SC) increased by three orders of magnitude as compared to phase inversion method (PI), from (7.36±0.37)×10-6 S cm-1 to (7.75±0.17)×10-4 S cm-1 with 40wt. % of MgTf at ambient temperature. Polymer electrolytes produced by both techniques obey Vogel-Tamman-Fulcher (VTF) theory which is related to the free volume model. The addition of MgTf reduces the glass transition temperature (Tg) significantly due to its plasticizing effect as shown in differential scanning calorimetry (DSC). PI technique produces higher thermal stability polymer electrolyte as proven in thermogravimetric analysis (TGA). Fourier Transform Infrared (FTIR) studies show the complexation between PVDF and MgTf. Polymer electrolyte produced by SC technique has wider electrochemical potential window compared to PI technique as illustrated in linear sweep voltammetry (LSV). Electric double layer capacitors (EDLCs) are fabricated using the most conducting polymer electrolyte produced by both techniques. Polymer electrolyte prepared by SC method obtained a higher specific capacitance EDLC than that of polymer electrolyte prepared by PI technique in EDLC application. However, EDLC containing PI-prepared polymer electrolyte exhibits better electrochemical stability over 100 cycles than the SCprepared polymer electrolyte as proven in galvanostatic charge-discharge (GCD) performances.