High-performance direct methanol alkaline fuel cells using potassium hydroxide-impregnated polyvinyl alcohol/carbon nano-tube electrolytes

This research focuses on improving direct methanol alkaline fuel cell (DMAFC) performance using hydroxide-potassium-doped polyvinyl alcohol/carbon nano-tube (PVA/CNT/KOH) electrolytes. The CNTs must be functionalized with PVA polymer chains to improve their dispersion in the polymer matrix and enhance the cell performance. A functionalized CNT load of 0.05% exhibits the highest cell voltage and power density among the PVA electrolytes containing 0–0.1% CNT. The cell voltage increases with the cell temperature between 30 and 60 °C. The open-circuit voltage and peak power density (Pmax) are highest at 6 M KOH concentration in the anode feed. A methanol concentration of 2 M produces a higher Pmax compared to concentrations of 1 M and 6 M methanol. The cell performance is enhanced by increasing the fuel flow rate into the anode. A Pmax of 68.1 mW cm−2 is obtained for a DMAFC employing PVA/0.05%CNT/KOH electrolyte at 60 °C with 2 M methanol and 6 M KOH as the anode feed at a flow rate of 30 mL min−1 and humidified oxygen at a flow rate of 100 mL min−1 to the cathode. To the best of our knowledge, this Pmax is the highest reported value in the literature for DMAFCs.

► KOH-doped PVA/CNT membrane electrolytes are prepared for fuel cell test. ► Operating condition is optimized for direct methanol alkaline fuel cells (DMAFC). ► High peak power density of 68.1 mW cm−2 is obtained at 60 °C for DMAFC.