Ionic currents in the presence of supporting electrolytes.

We analyze one-dimensional charge conduction within an ionic solution in the presence of supporting electrolytes that do not discharge on the electrodes. For thin Debye layers, numerical simulations predict current abatement, in agreement with experimental knowledge; in addition, they reveal unconventional features absent from classical analyses of binary solutions, such as high cation concentration near the electrodes. We derive a companion asymptotic description of the problem in the singular thin-Debye-layer limit, reproducing these attributes. The asymptotic analysis reveals a nested boundary-layer structure about the reactive electrodes and furnishes a universal current-voltage relation.