NASA's Glenn Research Center has developed a novel solid oxide fuel cell (SOFC) with five times the specific power density of currently available SOFCs. This highly efficient SOFC can operate on a wide range of both hydrogen and hydrocarbon-based fuels including methane, diesel, or jet fuel without reformers.
Rather than heavy metal interconnects, Glenn's innovative bi-electrode supported cell (BSC) uses a thin layer of electrically conductive LaCaCrO3 (LCC) for current collection. To improve strength during thermal cycling and simplify stack manufacture, its design is structurally symmetrical with a thin yttria-stabilized zirconia (YSZ) electrolyte supported on either side by a porous support structure.
Electrodes are made by freeze-casting, a modified tape casting technique that creates the many microchannels needed for gas diffusion in the YSZ electrode using green tape. Prior to electrode impregnation to create the anode and the cathode, the entire BSC support structure is sintered at a temperature of 1400 °C. This results in less internal resistance thanks to the nearly identical coefficients of thermal expansion of the YSZ electrolyte and LCC layer.
This design is highly versatile. The anode-impregnated material can easily be changed to nearly any metal such as tin or copper without any modification to the BSC, allowing for thinner layers and better performance characteristics. Also, since the BSC cells are fabricated entirely from ceramic materials, they can operate at higher temperatures, and the formation of hermetic, ceramic-to-ceramic seals is possible. The result is a BSC SOFC that can achieve high specific power densities that are five times higher than state-of-the-art (up to 2.5kW/kg), and a volumetric power density that is eight times higher than state-of-the-art (up to 7.5kW/L).