چكيده به لاتين
Fuel cells are known as promising technologies in conversion of chemical energy into electrical energy due to high efficiency and low environmental impacts. Solid alkaline fuel cells or anion exchange membrane fuel cells received more attention among all different types over the last decade. Solid alkaline fuel cells have some advantages over proton exchange membrane fuel cells such as: employing non-expensive metal catalysts (Ag, Ni, or Pd), effective reduction of oxygen in cathode, using various liquid fuels, minimizing corrosion problems under alkaline media and reducing fuel crossovering due to the counter-current migration of fuel and hydroxide ion.
In this study anion exchange membranes were prepared based on polysulfone and functionalized by trimethylamine and N,N,N',N'-tetramethyl-1,6-hexanediamine using chloromethylation, amination and alkalization steps. N,N,N',N'-tetramethyl-1,6-hexanediamine with long alkyl chain merged crosslinking and amination processes in one step and enhanced mechanical and chemical properties of the membranes. 1HNMR and FTIR spectra were obtained to confirm chloromethylation, amination and crosslinking processes. SEM micrographs were taken to observe the membranes morphology; TGA and DSC thermograms were considered for thermal analysis. Furthermore, mechanical strength and alkaline stability studies were performed to evaluate membranes performance. The prepared membranes showed through plane ionic conductivity in the range of 2-42 mS/cm at 30-80 °C in different relative humidities. In addition, the ion exchange capacity and anion transport number values were 1.6-2.1 meq/gr and 0.95-0.98, respectively. The water uptake and swelling ratio parameters were in acceptable ranges and illustrated that the prepared anion exchange membranes had anisotropic structure.
A single H2/O2 fuel cell test was carried out at 60 °C and resulted in open circuit voltage of 1.05 V and maximum power density of 110 mW/cm2 at current density of 195 mA/cm2. The experiments demonstrated that by choosing suitable proportions of amination and crosslinking agents, the prepared anion exchange membranes exhibited a well-balanced performance between ion transport properties, mechanical and chemical stability. Finally, the selected AEM is compared with commercial AEM. The fabricated membrane shows good conductivity relative to commercial one. But chemical stability of commercial membrane is better than the fabricated membrane. Therefore, according to the improved structural, thermal, mechanical and chemical stabilities, the prepared AEMs could be good candidate for solid alkaline fuel cell applications.
Keywords: Anion exchange membrane (AEM), Polysulfone (PSF), Ammonium groups, Crosslinking, Solid alkaline fuel cell (SAFC)
