Two-Phase Removal of Carbon Dioxide in a Direct Formic Acid Fuel Cell

Abstract

Direct Formic Acid Fuel Cells (DFAFC) are a potential substitute in portable power devices surpassing the capacity of conventional batteries in everyday items such as cell phones and laptops. The challenge of maintaining high formic acid (FA, HCOOH) concentrations within the catalyst layer at high current densities is due to the by-product carbon dioxide (HCOOH → CO2 +2H+ + 2e-) formation. The two-phase FA/CO2 results in mass transport limitations. Previous studies have shown enhanced current density performance when gaseous CO2 is removed through a semi-permeable separator near site of formation. The initial flow field prototype with a semi-permeable separator had significant issues with liquid FA breakthrough. Improved sealing surface designs are being investigated to improve the DFAFC’s efficiency. By altering the anode flow plate’s geometry and possibly changing the hydrophobic semi-permeable separator theoretically should show the much needed improvements that are required to meet portable power device power density requirements.