The highest voltage can be produced by using metals with the highest standard reduction potentials. In general, the further apart the metals are in the electromotive series, the higher the voltage produced. One of the combinations that can produce the highest voltage is using lithium metal (Li+) and fluorine gas (F2) since they have the highest reduction potentials. Another combination that can produce a high voltage is using magnesium metal (Mg2+) and silver metal (Ag+).
