Enhancing Air-Breathing Direct Methanol Fuel-Cell Performance by Optimizing Anode Flow-Channel Widths and Open Ratios of Cathode Current Collectors

Abstract

Air-breathing direct methanol fuel cells (AB-DMFCs) are used as a source of power for portable electronic devices. The width of the anode flow channel in AB-DMFCs plays a vital role in enhancing mass transfer to anode reaction sites. The transfer of oxygen to cathode reaction sites occurs through the current collector openings, and an optimum current collector open ratio (OR) was identified in this study. However, limited research is available on the effect of anode channel widths in combination with cathode current collector open ratios on the cell performance. This study analyzed the impact of anode single serpentine flow-channel widths and cathode current collector open ratios on AB-DMFC performance. The analysis was conducted in four stages. The first stage examined the influence of methanol concentration, varying from 0.5 to 2 M. In the second stage, three different anode flow-channel widths—1, 1.5, and 2 mm—were considered, with the methanol fuel flow rate varying from 0.5 to 2.5 mL/min. Experimental results revealed that fuel-cell performance increased with the increase of methanol concentration from 0.5 to 1.5 M and then decreased. Moreover, a fuel cell fitted with a flow field (FF) with a channel width of 1 mm provided better performance at a 2 mL/min methanol flow rate. Three different open ratios of cathode current collectors—45.40%, 55.40%, and 63.05%—were considered in the experiment, and the ambient temperature was varied from 30°C to 70°C. Among the three current collectors, the cell with a 55.40% current collector offered superior performance, and the optimal condition was observed at a methanol flow rate of 2 mL/min. The optimized combination of a fuel cell fitted with a 1-mm channel–width flow field and 55.40% open-ratio current collectors produced a maximum power density (MPD) of 10.416 mW·cm−2 at a 2 mL/min methanol flow rate.