Electrode potential relaxation in high temperature Li-Al/FeS engineering cells

The cell resistance and electrode polarization of high temperature Li-Al/FeS cells were investigated using a current-interruption, potential-relaxation tecnique. The special instrumentation possesses excellent long term stability and is capable of resolving a 1 mV. Six to seven orders of magnitude on the time scale can be covered. The polarization in most cases was about twice as great in the FeS electrode as in the Li-Al electrode. The potential relaxation times required to evaluate polarization were of the order of minutes, and the curves appear to contain three characteristic parts: the ohmic, the electrochemical, and the chemical and self-discharge portions. The electrode polarization for the respective electrodes for any state of charge or discharge was a nearly linear function of current density. A process associated with equalizing currents has been proposed to explain potential changes which occur in the cell after external current interruption. Equalizing currents also might explain the lack of electrode potential relaxation in the ..mu..s to 1 ms region of current interruption.