No abstract

The extremely high theoretical energy density of the lithium-oxygen couple makes it very attractive for nextgeneration battery development. However, there are a number of challenging technical hurdles that must be addressed for LiAir batteries to become a commercial reality. In this article, we demonstrate how the invention of water-stable, solid electrolyte-protected lithium electrodes solves many of these issues and paves the way for the development of aqueous and nonaqueous Li-Air batteries with unprecedented energy densities. We also show data for fully packaged Li-Air cells that achieve more than 800 Wh/kg.

Low cost, colloidal deposition methods have been utilized to produce novel solid oxide fuel cell structures on metal alloy support electrodes. YSZ films were deposited on iron-chrome supports on top of a thin Ni/YSZ catalytic layer, and sintered at 1350°C, in a reducing atmosphere. Dense, 20 m YSZ electrolyte films were obtained on highly porous stainless steel substrates.These metal-supported fuel cells were tested at 800 and 900°C, achieving power densities of over 200 mW/cm 2 at 900°C, using platinum paste cathodes. The cells have shown excellent resistance to thermal cycling, and open up a new low cost path to SOFC commercialization.

High-strength joining of Si 3 N 4 ceramics has been achieved by developing a process that effectively eliminates the seam, and may allow for fabrication of large or complex silicon nitride bodies. This approach to joining is based on the concept that when sintering aids are effective in bonding individual grains, they could be equally effective in joining bulk pieces of Si 3 N 4 . Optimization of the process led to Si 3 N 4 /Si 3 N 4 joints with room-temperature bend strengths as high as 950 MPa, corresponding to more than 90% of the bulk strength of the Si 3 N 4 . At elevated temperatures of 1000°and 1200°C joint strengths of 666 and 330 MPa, respectively, were obtained, which are the highest values reported to date for these temperatures. These bend strengths are also more that 90% of the strength of bulk Si 3 N 4 measured at these temperatures.