Nanostructured Electrode Materials for Electrochemical Supercapacitors

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This grant provides funding for the manufacturing and characterization of several nanostructured electrodes for electrochemical supercapacitors that exceed currently achieved energy storage capacity and display high charge/discharge rates. These electrodes are based on transition metal oxides and consist of four different nanostructures: (1) uniformly sized and unidirectionally aligned oxide nanorod arrays (perpendicularly standing on conductive substrate), (2) oxide nanotube arrays, (3) metal - oxide core-shell nanocable arrays, and (4) carbon cryogel - oxide nanocomposites. This research will take vanadium pentoxide as a model system to systematically study the influences of crystallinity, nanostructure and doping on intercalation capacity and charge/discharge kinetics. Core-shell nanocable arrays and carbon cryogel-oxide nanocomposites have both double layer supercapacitor and electrochemical pseudocapacitor characteristics, and thus promise significantly enhanced performance. The carbon cryogel-oxide nanocomposite is characterized by three-dimensional energy storage and release processes, while conventional electrochemical capacitors are inherently two dimensional systems. The energy stored in a three-dimensional electrode structure is larger than that in conventional capacitors. Other transition metal oxides including complex oxides, doped oxides, and amorphous oxides will also be explored for further enhancement of supercapacitor performance. If successful, this research will lead to the development of nanostructured electrodes with high energy storage capacity and fast charge/discharge rate with improved cyclic resistance. Additionally new manufacturing methods will be developed for the enhancement of material properties by careful design of nanostructures or microstructures and by precise control of composition. The study will result in a better fundamental understanding of the relationships between manufacturing, structure, composition, properties, and performance. The research will also broaden the application of nanostructures and nanomaterials by simply capitalizing the huge surface area and improved transport kinetics in nanostructures and nanomaterials without altering the physical properties associated with bulk materials. The benefit of this work also includes educating graduate and undergraduate students and attracting them into the field of energy related materials development and nanomanufacturing technology, and thus helping our nation stay in a leading position in this strategic field not only today but also in the future.