Novel Chitosan–Mg(OH)2 -Based Nanocomposite Membranes for Direct Alkaline Ethanol Fuel Cells

We have been involved in a project NanoElMem of 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 cm² 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 CS-based membranes. More here.M