Silver oxide battery

A silver oxide battery uses silver(I) oxide as the positive electrode (cathode), zinc as the negative electrode (anode), plus an alkaline electrolyte, usually sodium hydroxide (NaOH) or potassium hydroxide (KOH). The silver is reduced at the cathode from Ag(I) to Ag, and the zinc is oxidized from Zn to Zn(II).

The half-cell reaction at the positive plate:

${\displaystyle {\ce {Ag2O + H2O + 2e- -> 2Ag (v) + 2OH-}}}$, ${\displaystyle (E^{\circ }=+0.34{\text{ V}})}$

The half-cell reaction at the negative plate:

${\displaystyle {\ce {{Zn}+2OH^{-}->{\overset {Zinc~hydroxide}{Zn(OH)2}}+2e-}}}$, ${\displaystyle (E^{\circ }=-1.22{\text{ V}})}$

Overall reaction:

${\displaystyle {\ce {Zn + H2O + Ag2O -> Zn(OH)2 + 2Ag(v)}}}$, ${\displaystyle (E^{\circ }=+1.56{\text{ V}})}$

Overall reaction (anhydrous form):

${\displaystyle {\ce {Zn + Ag2O ->[{\ce {KOH/NaOH}}] ZnO + 2Ag (v)}}}$

Silver oxide battery used to power a quartz watch movement; battery is marked as containing no mercury

When first commercialized, all silver oxide batteries contained up to 0.2% mercury, incorporated into the zinc anode to inhibit corrosion from the alkaline environment. This corrosion would occur regardless of whether or not the battery was providing power, but shelf life was an important consideration when specifying silver oxide batteries. Sony started producing the first silver oxide batteries without added mercury in 2004.[6]

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• List of battery types

Wikimedia Commons has media related to Silver oxide batteries.

• SR (Silver Oxide Battery) from Maxell