The non-faradaic current associated with the charging of the electrical double layer at an electrode-solution interface, given by: \[i_{\mathrm{DL}}=\frac{\mathrm{d}(\sigma \ A)}{\mathrm{d}t}\] where \(\sigma \) = surface charge density of the double layer, \(A\) = area of the electrode-solution interface and \(t\) = time. Capital letters should be used as subscripts to avoid the possibility of confusing this symbol with that for the limiting diffusion current.