Enhancing the performance of direct methanol fuel cells via a new anode design for carbon dioxide bubbles removal

Abstract

Direct methanol fuel cells (DMFCs) are primary candidates to power portable electronics. However, carbon dioxide bubbles that are generated on the anode side block the flow of reactants and negatively affect the cell’s performance. Therefore, a new secondary hydrophobic degassing channel is attached to the top of the main anode channel. The proposed design introduces an upward capillary force on CO2 bubbles toward a degassing channel that collects the actuated bubbles and leads to reactant flow without bubbles in the main channel. In the current study, parallel and serpentine flow fields are investigated to assess the effect of the new design on bubble removal and overall cell performance. Thus, an experimental study is performed on a transparent DMFC using both optical observations and electrochemical characterization methods. Results show that the new design significantly enhances the cell’s performance at high current densities. In addition, the new design is advantageous in terms of removing bubbles away from the diffusion layer, especially for the parallel flow field configuration. A comparison between the output power of the new designs and the original ones indicated that the parallel flow field with the new design outperformed both the plain serpentine and the plain parallel flow field with over 14% and 23%, respectively. The advantage of using a parallel flow field is minimizing the pumping pressures required at the anode inlet, which decreases the parasitic power consumption. Based on the current findings, anode blocking can be prevented using the new design, which improves the performance of DMFCs in the mass transport region, and allows for a higher output power per cell.