No abstract

The present work describes novel polymer-based nanocomposite anion-exchange membranes (AEMs) with improved features for direct alkaline fuel cell applications. AEMs based on chitosan (CS), magnesium hydroxide (Mg(OH) 2), and graphene oxide (GO) with benzyltrimethylammonium chloride (BTMAC) as the hydroxide conductor were fabricated by a solvent casting method. To impart better mechanical properties and suppressed swelling, the enzymatic cross-linking with dodecyl 3,4,5-trihydroxybenzoate having C-10 alkyl chain was employed. The structure and surface morphology, KOH uptake and swelling ratio, ethanol permeability, mechanical property, ionic conductivity, cell performance, and stability of AEMs were investigated. The as-obtained AEMs showed improved hydroxide conductivity compared with previously reported CS AEMs. The highest value for hydroxide conductivity, 142.5 ± 4.0 mS cm −1 at 40°C, was achieved for the CS + Mg(OH) 2 + GO + BTMAC AEMs with an ethanol permeability value of 6.17 × 10 −7 ± 1.17 × 10 −7 cm 2 s −1 in spite of its relative high KOH uptake (1.43 g KOH/g membrane). The highest peak power density value of 72.7 mW cm −2 was obtained at 209 mA cm −2 when the pristine CS + Mg(OH) 2 AEM was used as the polymer electrolyte membrane in the direct alkaline ethanol fuel cell at 80°C. This is the highest reported power density value for CSbased membranes.