3.1.2 Transference Number Measurement
Using Wagner’s direct-current polarisation approach, illustrated in fig.
3, the total ionic transference number of the produced electrolyte
comprised of solid, flexible polymers was computed. This approach is
based on adopting suitable electrodes for a mixed conductor, it is
possible to suppress either ionic or electronic transport while still
determining the contribution of unsuppressed species. This approach
involves sandwiching the sample between two electrodes, one of which is
reversible (non-blocking) and can interchange both ions and electrons
with the electrolyte, and the other of which is blocking
(non-reversible) and can only do so. In order to polarise the sample, an
insignificant potential is provided throughout the cell, causing the
mobile ionic species to migrate in the direction of the blocking
electrode. A layer depleted of mobile ions is formed close to the
blocking electrode, which causes the current to decline over time
gradually. This example shows how the current is calculated as a
function of time till saturation level. This cell is polarised using
d.c. voltage; in this case, we polarised the cell up to 0.92 before
allowing it to self-discharge. The initial total draft
(It) in the current vs. time figure is the sum of the
improvement from ions and electrons. In contrast, the constant residual
current (Ie) is exclusively attributable to the ionic
current. The ionic transference number is thus provided by equation (2)
and (3):
\(t_{ion\ =\ 1-}\frac{I\mathbb{e}}{I_{t}}\) (2)