How to Define Electric Potential in a Polarized Polymer Electrolyte Why is it Important?*

Polymer electrolytes comprise mobile ionic species, usually both cations and anions, but are electronic insulators. The definition of electric potential is not trivial as the case of the metallic current collectors wherein the presence of excess electronic charge can readily be sensed by a voltmeter. Newman’s concentrated theory is built on potential measured using an electrode that undergoes a reversible electrochemical reaction. We apply this theory to polymer electrolytes that are examined under a constant direct current (dc). The concentration gradients in the electrolyte can be calculated without invoking the potential. For practical applications, however, it is important to know if the potential drop necessary to drive the current is within the range afforded by the chosen electrodes. We have worked through these relationship for homopolymer electrolytes. We are currently working on establishing these relationships in block copolymer electrolytes. We hope to present these results at the meeting.