title: Phase transition in porous electrodes. II. Effect of asymmetry in the ion size.
abstract: The electrochemical thermodynamics of electrolytes in porous electrodes is qualitatively different from that in the bulk with planar electrodes when the pore size is comparable to the size of the electrolyte ions. In this study, the effect of the ion size asymmetry on the thermodynamics in porous electrodes was studied by using Monte Carlo simulation. We used the electrolyte ions for which the size of the cations and that of anions is different. Due to the asymmetry in the ion size, the ionic structure and the way the surface charge is distributed on the electrode surfaces were found to be qualitatively different in the cathode and in the anode. In particular, for some ranges of applied voltage, the distribution of the surface charge induced on the electrode planes shows inhomogeneity, which is not intrinsic to the structure of the porous electrodes. The transition from the homogeneous to the inhomogeneous distribution of surface charge on changing the voltage is a second order phase transition.
authors.affiliation: Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan. k.kiyohara@aist.go.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Kiyohara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shioyama
authors.forename: Takushi
authors.initials: T
authors.lastname: Sugino
authors.forename: Kinji
authors.initials: K
authors.lastname: Asaka