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Electrochemical Conversion and Storage: Materials Design at the Nanometer Scale (14.11.2007)

The depletion of fossil fuels and the increasing environmental concerns
demand efficient, clean energy technologies.  Electrochemical conversion
and storage directly converts chemical energy to direct-current
electrical energy via electrochemical reactions, which has high
efficiency, and has shown great promise as key energy storage
technologies in hybrid energy systems for transportation and stationary
applications. However, practical energy and power densities and the cost
of electrochemical systems such as lithium rechargeable batteries and
fuel cells limit their competitiveness relative to conventional
technologies. These performance characteristics are strongly dependent
on the thermodynamics and kinetics of electrochemical reactions, and
transport within bulk materials. The ability to modify the reactivity of
materials through size provides a new opportunity in material design in
addition to controlling bulk composition and microstructure. Reduction
of particle size has been shown not only to provide more surface energy
but also to fundamentally change the catalytic activity of materials
such as gold and silver. We will discuss how the electronic, surface and
crystal structures can be tailored to design better nanoparticle
electrocatalysts for oxygen reduction, and better materials for lithium
storage.

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