Heterogeneous nanowires and nanotubes: fast electrochemistry, from electrochromics to high power energy storage

Sang Bok Lee
Department of Chemistry and Biochemistry
Professor and Deputy Director
NEES-Energy Frontier Research Center
University of Maryland
Chemistry Building, College Park, MD 20742, USA

This talk will begin with the electrochemical growth of the conductive polymer (CP) nanotubes and the heterogeneous CP-metal oxide composite nanowires and their applications for ultrafast electrochromic display and high power energy storage applications. Fast electrochemistry of nanotube-structured CP enables us to design extremely fast charge transport devices due to thin nature of nanotube wall and well-aligned array structure. The fast electrochromics of Poly (3,4-ethylenedioxythiophene) (PEDOT) will be discussed and demonstrated as a proof of the fast redox reaction and for display application.  The same concept of fast redox reaction can be applied to high power energy storage device such as supercapacitor and high-power battery. Again, nanostructured materials, as noted above, offer vast gains in power density by increasing surface area and reducing path lengths for electron and ion transport. Heterogenous nanostructured oxide materials separate the multiple functionalities (large energy storage, rapid ion transport, high electrical conductivity, high mechanical stability) to different materials, realizing a combined material structure with much higher synergistic performance. In addition, dense arrays of nanostructures with precisely controlled dimension and composition are essential for understanding the science of nanoscale electrochemistry and are necessary to realize high power and energy density.