Thursday, February 23 2012 2:00 p.m.
Room 610, M&M Building
Douglas B. Chrisey
Department of Material Science and Engineering, Department of Biomedical Engineering
Rensselaer Polytechnic Institute, Troy, NY, 12180
Abstract
Renewable energy sources require large-scale power storage so that their inherently intermittent supply of power can meet demand. For capacitive energy to have the necessary high volumetric and gravimetric energy storage density this will require the dielectric layer to simultaneously possess a high dielectric constant and a high breakdown strength, e.g., in excess of 10,000 and 1 MV/cm, respectively. To be a realistic solution for renewable energy storage, it must also be low cost and scalable, i.e., no roadblocks from the laboratory prototype to large scale production, and to achieve the all of the aforementioned requirements we have exploited a glass-ceramic phase. It is expected that glass-ceramics composites will have higher breakdown strength than that of a sintered ceramic alone, because the glass would displace the air-filled voids. Due to the dielectric mixing rule, the dielectric constant of the composite mixture will then be limited by the low permittivity of the glass phase in comparison to the ceramic phase. In our work, we use a glass phase that can undergo a phase transformation into BaTiO3-precipitating glass-ceramic by controlled crystallization (annealing temperature). The benefit of doing this is that we achieve a higher dielectric constant of composite mixture, due to the additional high dielectric constant BaTiO3 phase, while also improving the high breakdown strength. It was demonstrated that this BaTiO3-precipitaing glass-ceramic and BaTiO3 ceramic composite are promising for improved dielectric properties for high-density energy storage capacitors.