voltaic couple

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Two dissimilar conductors in contact or in the same electrolytic solution, resulting in a difference of potential between them. Also called galvanic couple.

Wiktionary

1. n. The pair of plates (made of different metals or other conductive materials), and separated by an electrolyte, which form a voltaic cell (in a battery, for example).

GNU Webster's 1913

1. adj. a single pair of the connected plates of a battery.