Alkaline direct ethanol fuel cell performance using alkali-impregnated polyvinyl alcohol/functionalized carbon nano-tube solid electrolytes

• Carbon nano-tubes are functionalized with polyvinyl alcohol.
• KOH-doped PVA/m-CNT membrane electrolyte is prepared and characterized.
• Ion conductivity of composite electrolyte is enhanced by 51.9%.
• Pmax of ADEFC increases from 31 to 65 mW cm−2 using the composite.

This study investigates the application of a polyvinyl alcohol (PVA)/functionalized carbon nano-tubes (m-CNTs) composite in alkaline direct ethanol fuel cells (ADEFC). The m-CNTs are functionalized with PVA using the ozone mediation method, and the PVA composite containing the modified CNTs is prepared. Adding m-CNT into the PVA matrix enhances the alkaline uptake and the ionic conductivity of the KOH-doped electrolyte. Meanwhile, the m-CNT-containing membrane exhibited a lower swelling ratio and suppressed ethanol permeability compared to the pristine PVA film. The optimal condition for the ADEFC is determined to be under operation at an anode feed of 3 M ethanol in a 5 M KOH solution (at a flow rate of 5 cm3 min−1) with a cathode feed of moisturized oxygen (with a flow rate of 100 cm3 min−1) and the KOH-doped PVA/m-CNT electrolyte. We achieved a peak power density value of 65 mW cm−2 at 60 °C, which is the highest among the ADEFC literature data and several times higher than the proton-exchange direct ethanol fuel cells using sulfonated membrane electrolytes. Therefore, the KOH-doped PVA/m-CNT electrolyte is a suitable solid electrolyte for ADEFCs and has potential for commercialization in alkaline fuel cell applications.

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