In Situ Molecular Level
Measurements of Ion Dynamics
in an Electrochemical Capacitor
- Publication date
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Abstract
Improving the energy storage capability of batteries
and capacitors
is inherently dependent on clarifying our understanding of ion dynamics
of advanced electrolytes in a variety of materials. Herein we report
a new attenuated total reflectance–surface-enhanced infrared
absorption spectroscopy technique that can selectively and simultaneously
measure both cation and anion transport of an ionic liquid (1-ethyl-3-methylimidazolium
triflate (EMIm-Tf)) in a functioning electrochemical pseudocapacitor
(actuator). This new capacitor–spectroscopy technique was utilized
to probe the gold current collector/RuO<sub>2</sub> electrode interface
during both square wave and cyclic voltammetry experiments. Results
show that the cations and anions transport as aggregates and the cation
dominates and dictates the direction of ion transport in these devices.
Results also show that ion dynamics in pseudocapacitors is a diffusion-limited
process