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|Title:||ALS Seminar: "Investigation of structure-property relations in nanocomposites for energy storage"|
|When:||05/23/2013 1:00 PM - 2:00 PM|
|Description:||ALS Special Seminar:|
INVESTIGATION OF STRUCTURE-PROPERTY RELATIONS IN NANOCOMPOSITES FOR ENERGY STORAGE
6-2202 Conf Room
High energy density capacitors are critically important in advanced electronic devices and electric power systems that rely on pulsed-power, such as defibrillators, and high power microwaves. Nanocomposites have great potential as high energy capacitors, since they combine the high breakdown strength of polymers with the high dielectric permittivity of ceramics, to produce energy density greater than either in its pure form. This talk will present the relationship between filler’s structure (aspect ratio and orientation) and energy storage performance of nanocomposites. Initially, the effect of the filler’s aspect ratio on the nanocomposite’s energy density was studied. It is demonstrated that the nanocomposites with lead zirconate titanat (PZT) nanowires (NWs) show 77.8% increase in energy density compared to samples with PZT nanorods at 50 % volume fraction. Second, this work investigates the role of NW orientation towards the improvement in the energy density of nanocomposites. It is demonstrated that the energy storage capacity of the nanocomposite can be enhanced by 51.6% through the alignment of PZT nanowires in the direction of the applied electric field as compared to the sample with randomly aligned nanowires at 20% volume fraction. Further research is performed to quantify the dielectric constant of nanocomposites as a function of both aspect ratio and orientation factor of the fillers. Based on these findings, two different types of nanocomposites with high energy density are fabricated. The nanocomposites with 7.5 vol.% Ba0.2Sr0.8TiO3 NWs in polyvinylidene fluoride (PVDF) are shown to have an ultra-high energy density of 14.86 J/cc at 450 MV/m with microsecond discharge time speed, which exceeds those reported in the literature for ceramic/polymer composites, and is 1138% greater than the reported commercial capacitor biaxial oriented polypropylene (1.2 J/cc at 640 MV/m). This work is trying to serve to disseminate a state-of-the-art method of preparing nanocomposites with high energy density and fast discharge for development of future pulsed-power capacitors.