Advances in metal-cation-free, quaternary ammonium, polymer alkaline anion exchange membranes (AAEMs) have provided a recent resurgence of interest in the alkaline fuel cell (AFC). The alkaline environment supported by the AAEM offers several potential advantages, including opportunities for the use of non-noble metal catalysts with high energy density and logistically favorable fuels and oxidants, such as methanol and air. However, recent experimental literature has shown that the AAEM derived AFCs have considerable resistive losses that can be attributed to the AAEM. This work describes a dusty fluid model used to predict AAEM conductivities as a function of relative humidity and membrane properties in an initial attempt at forming a framework for understanding the processes at work. A percolation model is used to account for the membrane structure. The model is validated using Nafion 115 conductivity data.

A high-resolution, nondestructive X-ray computed tomography ͑XCT͒ technique is applied to image the three-dimensional ͑3D͒ microstructure of a solid oxide fuel cell ͑SOFC͒ composed of a solid yttria-stabilized zirconia ͑YSZ͒ electrolyte and a porous nickel YSZ ͑Ni-YSZ͒ anode. The X-ray microscope uses the 8 keV Cu K␣ line from a laboratory X-ray source, with a reflective condenser optic lens providing a spatial resolution of 42.7 nm. The reconstructed volume data is visualized as 3D images and further postprocessed in binary-image format to obtain structural parameters. The porosity is calculated using a voxel counting method, and tortuosity is evaluated by solving the Laplace equation. A 3D representation of the microstructure is used to calculate true structural parameters and carry out a detailed study of the gas transport within an SOFC electrode at the pore scale. Simulation of multicomponent mass transport and electrochemical reactions in the anode microstructure using the XCT data as geometric input illustrate the impact of this technique on SOFC modeling.

Abatement of CO 2 emissions from existing fossil-fueled power plants is currently the sole near-term solution to stabilize CO 2 concentration in the atmosphere. Separation and capture of CO 2 from process streams of these power plants is the first step toward this effort. In this paper, we report a high flux membrane consisting of highly and efficiently interconnected three-dimensional ionic channels prepared from a combined ''co-precipitation'' and ''sacrificial-template'' synthesis. The membranes exhibit remarkable CO 2 permeation characteristic, achieving a CO 2 flux density two orders of magnitude higher than other similar systems reported in the literature. The experimental results also have an excellent agreement with the theoretical predictions. Overall, the demonstrated dual-phase membranes show a great promise for selective pre-combustion CO 2 separation.

Present solid oxide fuel cells (SOFCs) use complex materials to provide (i) sufficient stability and support, (ii) electronic, ionic, and mass transport, and (iii) electrocatalytic activity. However, there is a limited quantitative understanding of the effect of the SOFC's three dimensional (3D) nano/microstructure on electronic, ionic, and mass-transfer-related losses. Here, a nondestructive tomographic imaging technique at 38.5 nm spatial resolution is used along with numerical models to examine the phase and pore networks within an SOFC anode and to provide insight into the heterogeneous microstructure’s contributions to the origins of transport-related losses. The microstructure produces substantial localized structure-induced losses, with approximately 50% of those losses arising from phase cross-sectional diameters of 0.2μm or less.

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