Electrochemical effects in metal(1) — Polymer-metal(2) cells

It is well known that a polymer film on which two electrodes of dissimilar metals are evaporated may behave as a battery. We show that the behavior of such systems may be understood by assuming that the reaction rate in the electrochemical cell is controlled by the (polymer) electrolyte resistance. From this, experimentally observed variations of voltage with temperature and with polymer thickness can easily be explained. In these systems one observes that open-circuit voltages under vacuum and under atmosphere are significantly different. We have studied the influence of a number of gases and find that water vapor is responsible for this effect. We present a semi-empirical model to describe this dependence.