Over-limiting currents and deionization “shocks” in current-induced polarization: Local-equilibrium analysis

摘要: article i nfo The problem is considered theoretically of dynamics current-induced concentration polarization inter- faces between ideally perm-selective and non-ideally ("leaky") ion-exchange media in binary electrolyte solutions under galvanostatic conditions at negligible volume flow. In contrast to the previous studies, analysis systematically carried out terms local thermodynamic equilibrium approx- imation electric neutrality virtual solution. For macroscopically homogeneous media, this enables one obtain model-independent results quadratures for stationary state as well an approximate scaling-form solution transient response step-wise increase electric-current density. These are formulated such phenomenological properties "leaky" medium ion transport numbers, diffusion permeability salt specific chemical capacity. An easy-to-solve numerically 1D PDE also same terms. A systematic parametric study within scope fine-pore model volumetric fixed charges diffusivities ions symmetri- cal electrolyte. While studies paid principal attention shape propagation rate so-called deionization "shocks", we consider detail time evolution voltage drop interface concentration. Our confirms previously predicted pattern propagating "shocks" but reveals several novel features. particular, demonstrate that deionization-shock really pronounced only intermediate ratios fixed-charge concen- tration initial quite high steady-state voltages where used applicable relatively early stages concentration-polarization process.