A silver oxide battery is a primary cell, in which the reaction cannot be reversed by running current into the cell. It is also known as a silver–zinc battery, because they are typically composed of silver-oxide, which is used as the positive electrode, and zinc, which is used as the negative electrode. Silver oxide batteries have a long durability and very high energy/weight ratio, but unaffordable cost for most applications due to the high price of silver. They are available in either very small sizes as button cells where the amount of silver used is small and not a significant contributor to the overall product costs, or in large custom design batteries where the superior performance characteristics of the silver oxide chemistry outweigh cost considerations.
These batteries were mainly developed for aircraft, and they have long been used in space launchers and crewed spacecraft where their short cycle life is not a drawback. Non-rechargeable silver-zinc batteries powered the Apollo Lunar Module (Apollo spacecraft), lunar rover (space exploration vehicle) and life support backpack (“backpack” of a spacesuit). The primary power sources for the command module (one of the spacecraft) were the hydrogen/oxygen fuel cells (electro-chemical cells) in the service module. They provided greater energy densities than any conventional battery. After the Apollo 13 (spacecraft) near-disaster, an auxiliary silver-zinc battery was added to the service module as a backup to the fuel cells.
A silver oxide battery is a small-sized primary battery using silver oxide as the positive electrode (cathode), zinc as the negative electrode (anode) plus an electrolyte (a solution that conducts electricity), usually sodium hydroxide (NaOH) or potassium hydroxide (KOH). Electrode is an electrical conductor. The silver is reduced (gains electrons) at the cathode from and the zinc is oxidized (loss of electrons) at the anode. The chemical reaction that takes place inside the battery is as shown below:
|Zn + Ag2O --> ZnO + 2 Ag|
Zinc is the activator in the negative electrode and corrodes (gets rusted) in alkaline solution of KOH or NaOH. When this happens, it becomes difficult to maintain the capacity of the unused battery. The zinc corrosion causes electrolysis (Chemical decomposition produced by passing an electric current through a liquid or solution containing ions) in the electrolyte, resulting in the production of hydrogen gas, a rise of inner pressure and expansion of the You do not have access to view this node.