Prediction and Analysis of Current–Voltage Characteristic of Transfer of Binary Salt Ions in Diffusion Layer

This work is aimed at derivation of equation of current–voltage characteristic (CVC) of nonstationary transfer of 1:1 electrolyte in depleted layer near ion exchange membrane, analysis of this equation, and determination of fundamental regularities of its variations. This was aided by construction of circuit diagram of diffusion layer/cation exchange membrane. It is demonstrated that total current in circuit is comprised of conduction current, determined by the flow of salt ions, and displacement current, which is consumed for generation and development of space charge region. The total current in circuit upon calculation of CVC varies in time as a consequence of increment of potential jump at moderate rate, thus, its variation can be considered as slow. In this case, the displacement current actually does not pass through the diffusion layer and it should not be considered upon calculation of CVC. The proposed equation of CVC is stable with regard to rounding errors, and at moderate rates of potential jump, it coincides with current–voltage characteristic for stationary case. The effect of nonstationarity at high rates of increment in potential jump has been analyzed