Voltammetry and electrochemical impedance spectroscopy of multilayer ion-exchange membranes

Abstract

A measurement system based on a rotating membrane disk (RMD) was developed. The system
allows registration of the current-voltage characteristics (CVC) and the effective ion transport numbers, along
with measurement of the electrochemical impedance frequency spectrum of a multilayer ion-exchange
membranes under stabilized diffusion boundary layer conditions. Salt ions and water molecules dissociation
products transport through the multi-layered ion exchange membrane were investigated in 0.01 M sodium
chloride solution. Frequency spectrums of the electrochemical impedance of an asymmetric bipolar
membranes (aBPM) with a cation exchange layer thickness (MF-4SC) of 10 and 30 microns at different
densities of the polarizing current, in a wide range of rotational speeds of the membrane disc were measured.
It is shown that an increase in the current density leads to an expansion of the impedance spectrum of studied
aBPM, and the ratio of deposits of a chemical reaction (Gerisher impedance) and electrodiffusion ion
transport salt (Warburg finite diffusion impedance) shifts towards a chemical reaction.