Importance of balancing membrane and electrode water in anion exchange membrane fuel cells

Anion exchange membrane fuel cells (AEMFCs) offer several potential advantages over proton exchange membrane fuel cells (PEMFCs), most notably to overcome the cost barrier that has slowed the growth and large scale implementation of fuel cells for transportation. However, limitations in performance have held back AEMFCs, specifically in the areas of stability, carbonation, and maximum achievable current and power densities. In order for AEMFCs to contend with PEMFCs for market viability, it is necessary to realize a competitive cell performance. This work demonstrates a new benchmark for a H2/O2 AEMFC with a peak power density of 1.4 W cm−2 at 60 °C. This was accomplished by taking a more precise look at balancing necessary membrane hydration while preventing electrode flooding, which somewhat surprisingly can occur both at the anode and the cathode. Specifically, radiation-grafted ETFE-based anion exchange membranes and anion exchange ionomer powder, functionalized with benchmark benzyltrimethylammonium groups, were utilized to examine the effects of the following parameters on AEMFC performance: feed gas flow rate, the use of hydrophobic vs. hydrophilic gas diffusion layers, and gas feed dew points

Carbonate Dynamics and Opportunities With Low Temperature, Anion Exchange Membrane-Based Electrochemical Carbon Dioxide Separators

Fossil fuel power plants are responsible for a significant portion of anthropogenic atmospheric carbon dioxide (CO2) and due to concerns over global climate change, finding solutions that significantly reduce emissions at their source has become a vital concern. When oxygen (O2) is reduced along with CO2 at the cathode of an anion exchange membrane (AEM) electrochemical cell, carbonate and bicarbonate are formed which are transported through electrolyte by migration from the cathode to the anode where they are oxidized back to CO2 and O2. This behavior makes AEM-based devices scientifically interesting CO2 separation devices or “electrochemical CO2 pumps.” Electrochemical CO2 separation is a promising alternative to state-of-the-art solvent-based methods because the cells operate at low temperatures and scale with surface area, not volume, suggesting that industrial electrochemical systems could be more compact than amine sorption technologies. In this work, we investigate the impact of the CO2 separator cell potential on the CO2 flux, carbonate transport mechanism and process costs. The applied electrical current and CO2 flux showed a strong correlation that was both stable and reversible. The dominant anion transport pathway, carbonate vs. bicarbonate, undergoes a shift from carbonate to mixed carbonate/bicarbonate with increased potential. A preliminary techno-economic analysis shows that despite the limitations of present cells, there is a clear pathway to meet the US DOE 2025 and 2035 targets for power plant retrofit CO2 capture systems through materials and systems-level advances

Carbonate Dynamics and Opportunities With Low Temperature, Anion Exchange Membrane-Based Electrochemical Carbon Dioxide Separators

Fossil fuel power plants are responsible for a significant portion of anthropogenic atmospheric carbon dioxide (CO2) and due to concerns over global climate change, finding solutions that significantly reduce emissions at their source has become a vital concern. When oxygen (O2) is reduced along with CO2 at the cathode of an anion exchange membrane (AEM) electrochemical cell, carbonate and bicarbonate are formed which are transported through electrolyte by migration from the cathode to the anode where they are oxidized back to CO2 and O2. This behavior makes AEM-based devices scientifically interesting CO2 separation devices or “electrochemical CO2 pumps.” Electrochemical CO2 separation is a promising alternative to state-of-the-art solvent-based methods because the cells operate at low temperatures and scale with surface area, not volume, suggesting that industrial electrochemical systems could be more compact than amine sorption technologies. In this work, we investigate the impact of the CO2 separator cell potential on the CO2 flux, carbonate transport mechanism and process costs. The applied electrical current and CO2 flux showed a strong correlation that was both stable and reversible. The dominant anion transport pathway, carbonate vs. bicarbonate, undergoes a shift from carbonate to mixed carbonate/bicarbonate with increased potential. A preliminary techno-economic analysis shows that despite the limitations of present cells, there is a clear pathway to meet the US DOE 2025 and 2035 targets for power plant retrofit CO2 capture systems through materials and systems-level advances

Anion-exchange membranes in electrochemical energy systems

\u3cp\u3eThis article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current state-of-the-art, technological and scientific limitations, and the future challenges (research priorities) related to the use of anion-exchange membranes in these energy technologies. All the references that the authors deemed relevant, and were available on the web by the manuscript submission date (30\u3csup\u3eth\u3c/sup\u3e April 2014), are included.\u3c/p\u3

Palladium-Based Electrocatalysts for Oxygen Reduction Reaction

Fuel cells are clean energy devices that are expected to help address the energy and environmental problems in our society. Platinum-based nanomaterials are usually used as the electrocatalysts for both the anode (hydrogen oxidation) and cathode (oxygen reduction) reactions. The high cost and limited resources of this precious metal hinder the commercialization of fuel cells. Recent efforts have focused on the discovery of palladium-based electrocatalysts with little or no platinum for oxygen reduction reaction (ORR). This chapter overviews the recent progress of electrocatalysis of palladium-based materials including both extended surfaces and nanostructured ones for ORR. © Springer-Verlag London 2013.[Shao, M.] UTC Power, 195 Governor's Highway, South Windsor, CT, 06074, United State