Preparation And Performance Of Grafting PS/PES Anion Exchange Membrane

The PEMFC and DMFC have two main problems. One is sluggish oxygen reduction kinetics at the cathode; the other is methanol crossover which leads to a reduced potential at the cathode and a lowering of the overall fuel cell voltage, with a consequential lowering of cell efficiencies. The use of AAEM may meet the challenges above. This is mainly due to facile kinetics at the cathode as well as at the anode in alkaline media. The ion transport within the membrane will be from the cathode to the anode, opposing the direction of methanol crossover from anode to cathode. Cheaper non-noble metal catalysts can also be used ( such as nickel and silver) to reduce cost.A widely quoted concern with AAEM is membrane stability in alkaline form, especially at elevated temperature. Instability is mainly due to direct nucleophilic displacement of the ammonium group by OH- anions. To solve the problem, 1,3-dibromopropane, 1,4-dibromobutane and 1,6-dibromohexane are used as the alkylation reagent, to change the CH2 between the benzene ring and the quaternary ammonium to (CH2)3, (CH2)4 and (CH2)6. The water content, IEC, conductivity and methanol permeability of the AAEM with different spacer chain are measured.The methanol permeability of the AAEM with different spacer chains is from 9.01×10-8cm2/s to 4.44×10-7cm2/s. The methanol resistance of the AAEM with different spacer chains is much better than that of membrane Nafion115. The conductivity of the AAEM with different spacer chains is from 4.09315×10-4S/cm to 2.32×10-3S/cm. The conductivity of the AAEM with different spacer chains is much lower than that of commercial membrane DF120. But Thermal stability of the AAEM with different spacer chains is greatly improved.