Abstract:

Polyvinyl alcohol-graft-N-vinylimidazole fluoroboric acid salt copolymer(PVA-g-VyImBF₄) was synthesized with main raw materials such as polyvinyl alcohol(PVA), N-vinylim-idazole(VyIm) and fluoroboric acid(HBF₄). With phosphotungstic acid(PTA) and ionic liquid(PEG400IMBF4) as materials of improving practicability, PVA-g-VyImBF₄/PTA/PEG400IMBF₄ polymer electrolyte composite membrane was prepared via solution casting method. The polymer structure was characterized by means of Fourser transform infrared spectroscopy(FTIR), differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and scanning electron microscope(SEM). The electrochemical performance of polymer electrolyte membrane was studied by alternating current(AC) impedance and cyclic voltammetry. The results show that the conductivity of the polymer electrolyte membrane can get to 3.267×10^-3 S/cm measured at room temperature and the electrochemical stability window can get to 4.4 V when m(PVA-g-VyImBF₄): m(PTA): m(PEG400IMBF₄) is 4: 2: 1.8.

Key words: PVA-g-copolymer, Ionic liquid, N-Vinylimidazole, Phosphotungstic acid, Conductivity