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Silver oxide battery
Silver oxide cells
Specific energy130 Wh/kg[1]
Energy density500 Wh/L[1]
Specific powerHigh
Charge/discharge efficiencyN/A
Time durabilityHigh
Cycle durabilityN/A
Nominal cell voltage1.55V
Several sizes of button and coin cells, some of which are silver oxide

A silver oxide battery (IEC code: S) is a primary cell using silver oxide as the cathode material and zinc for the anode. These cells maintain a nearly constant nominal voltage during discharge until fully depleted.[2] They are available in small sizes as button cells, where the amount of silver used is minimal and not a prohibitively expensive contributor to the overall product cost.

Silver oxide primary batteries account for 30% of all primary battery sales in Japan (64 out of 212 million in February 2020).[3]

Silver oxide batteries were used on Apollo program lunar missions for the lunar module and lunar rover power supplies because of their high energy-to-weight ratio.[4][5]


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:


The half-cell reaction at the negative plate:


Overall reaction:


Overall reaction (anhydrous form):

Mercury content

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

Until recently,[when?] all silver oxide batteries contained up to 0.2% mercury.[citation needed] The mercury was incorporated into the zinc anode to inhibit its continuous corrosion in the alkaline environment, which would otherwise occur regardless of whether or not the battery was providing power. Sony started producing the first silver oxide batteries without added mercury in 2004.[6]

See also


  1. ^ a b "ProCell Silver Oxide battery chemistry". Duracell. Archived from the original on 2009-12-20. Retrieved 2009-04-21.
  2. ^ "Silver Oxide Batteries". muRata. Retrieved 25 November 2020.
  3. ^ "Monthly Battery Sales Statistics". MoETI. May 2020. Archived from the original on 2010-12-06. Retrieved 2020-08-07.
  4. ^ Clemens, Kevin (2019-07-05). "The Batteries That Powered the Lunar Module". Retrieved 2021-02-02.
  5. ^ Lyons, Pete; "10 Best Ahead-of-Their-Time Machines", Car and Driver, Jan. 1988, p.78
  6. ^ World’s First Environmentally Friendly Mercury Free Silver Oxide Batter. September 29, 2004.