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A silver-oxide battery (IEC code: S) is a primary cell with a very high energy/weight ratio. Available either in small sizes as button cells (where the amount of silver used is minimal and not a significant contributor to the product cost), or in large custom designed batteries where the superior performance of the silver-oxide chemistry outweighs cost considerations. These larger cells are mostly found in applications for the military, for example in Mark 37 torpedoes or on Alfa-class submarines. In recent years they have become important as reserve batteries for manned and unmanned spacecraft. Spent batteries can be processed to recover their silver content. Silver-oxide primary batteries account for over 20% of all primary battery sales in Japan (67,000 out of 232,000 in September 2012).〔() Monthly battery sales statistics - MoETI - March 2011〕 A related rechargeable secondary battery usually called a silver–zinc battery uses a variation of silver–oxide chemistry. It shares most of the characteristics of the silver-oxide battery, and in addition, is able to deliver one of the highest specific energies of all presently known electrochemical power sources. Long used in specialized applications, it is now being developed for more mainstream markets, for example laptop batteries. ==Chemistry== A silver-oxide battery uses silver 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 chemical reaction that takes place inside the battery is the following: The silver–zinc battery is manufactured in a fully discharged condition, and has the opposite electrode composition, the cathode being of metallic silver, while the anode is a mixture of zinc oxide and pure zinc powders. The electrolyte used is a potassium hydroxide / water solution. During the charging process, silver is first oxidized to silver(I) oxide: 2Ag(s) + 2OH− → Ag2O + H2O + 2e− and then to silver(II) oxide: Ag2O + 2OH− → 2AgO + H2O + 2e−, while the zinc oxide is reduced to metallic zinc: 2Zn(OH)2 + 4e− = 2Zn + 4OH−. The process is continued until the cell potential reaches a level where the decomposition of the electrolyte is possible at about 1.55 Volts. This is taken as the end of a charge, as no further charge is stored, and any oxygen which might be generated poses a mechanical and fire hazard to the cell. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Silver-oxide battery」の詳細全文を読む スポンサード リンク
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