1. Nonlinear capacitance and electrochemical response of ionic liquid-ionic polymers
- Author
-
Jacob D. Davidson and Nakhiah C. Goulbourne
- Subjects
Materials science ,Differential capacitance ,Analytical chemistry ,General Physics and Astronomy ,Ionic bonding ,Thermodynamics ,Method of matched asymptotic expansions ,Capacitance ,Ion ,chemistry.chemical_compound ,Ionic potential ,chemistry ,Ionic strength ,Ionic liquid - Abstract
In this paper we present a physics-based model for the electrochemical response of ionic liquid-ionic polymer transducers (IPTs) and show how the mobile ionic liquid ions influence the charging characteristics and actuation performance of a device. It is assumed that a certain fraction of the ionic liquid ions exist as “free,” making for a total of 3 mobile ions. This leads to predictions of distinctly different charging characteristics for ionic liquid versus water-based IPTs, since for the latter there is only a single mobile ion. The large ionic liquid ions are modeled by including steric effects in a set of modified Nernst-Planck/Poisson equations, and the resulting system of equations is solved using the method of matched asymptotic expansions (MAE). The inclusion of steric effects allows for a realistic description of boundary layer composition near actuator operating voltages (~1 V). Analytical expressions for the charge transferred and differential capacitance are derived as a function of the frac...
- Published
- 2011