Synthesis and Characterization of New Ionic and Mixed Ionic/Electronic Conductors

In a constantly growing and developing world, there is a great need to develop new forms of clean energy generation. Many solutions have been proposed to ameliorate these global concerns, which include fuel cell technology and new processes for reducing polluting chemicals in the atmosphere. These technologies are still in their infancy and require further development before becoming viable options. In the case of fuel cells, particularly solid oxide fuel cells, and CO2 separation membranes, there is a need to develop ion conducting materials that are highly efficient, less costly to synthesize, and can perform strongly under many real-world conditions. The need for further developing these ion conductors is currently one of the most important final steps required to push these new technologies into the market. The research presented here focuses on the synthesis and characterization for several ion conductor systems intended for efficient energy conversion applications. Using a novel transient liquid phase sintering method, we demonstrate that it is possible to synthesize dense BaZr0.8Y0.2O3-δ (BZY20) at 1300°C, a lower temperatures than previously reported, using barium gallate as a sintering flux. Focusing on a new family of oxide-ion conductors, Sr1-xKxSi1-yGeyO3-0.5x, gallium served as a replacement germanium in an effort to further increase the oxide-ion conductivity. Unfortunately, the replacement of Ge with Ga was found to decrease the overall oxide-ion conductivity and microstructural morphology. Through the addition of an Al2O3 layer to a porous silver matrix, we show that CO2 permeation flux density through a new MECC membrane can be enhanced as a result of improved retention of molten carbonate in the silver matrix. Pore size and distribution in the silver matrix were found to greatly depend on the concentration of Al2O3 suspension

A High Energy Density All Solid-State Tungsten-Air Battery

An all solid-state tungsten–air battery using solid oxide–ion electrolyte is demonstrated as a new chemistry for advanced energy storage. The unique design of separated energy storage from the electrodes allows for free volume expansion–contraction during electrical cycles and new metal–air chemistry to be explored conveniently

High Conductivity Mixed Oxide-Ion and Carbonate-Ion Conductors Supported by a Prefabricated Porous Solid-Oxide Matrix

A novel two-phase mixed oxide-ion and carbonate-ion conductor (MOCC) has been recently developed for intermediate temperature solid-oxide fuel cells and CO2 separation membranes. With conventional mixing–pressing ceramic fabrication technique it is difficult to obtain a MOCC with high mechanical strength and high oxide-ion conductivity due to the low sintering temperature. In this study, a samarium doped ceria (SDC, Ce0.8Sm0.2O1.9) is selected to demonstrate the prefabrication of porous matrix by the “sacrificial template” methodology with Ni as the template material. The microstructure of the SDC matrix characterized with a 3D X-ray computed tomography and a SEM imaging reveals a uniform distribution of homogeneous micro-pores across the solid-oxide matrix. A Li–Na-carbonate-impregnated MOCC supported by a 40% porous SDC matrix shows an effective ionic conductivity of 0.55 and 0.46 S/cm at 650 and 600 °C, respectively, the highest values reported so far among similar systems. Keywords: Mixed ionic conductors, Effective ionic conductivity, Porous structure, Melt infiltratio