The pedigree of silver oxide batteries dates back to the early 1800s, after Alessandro Volta invented the world’s first battery pile. But the visionary was not content with using zinc and copper electrodes stacked in a pile, and so he explored other materials.
One of his early experiments used a circle of cups containing a salty water electrolyte. Alternating cups had zinc or silver strips joined together with a wire. History recalls that 20 cups delivered sufficient energy to electrolyse the water, and produce hydrogen gas.
Fast Forward to Modern Silver Oxide Batteries
Silver is an expensive metal, and so modern silver oxide batteries use a silver compound instead. These primary, non-rechargeable cells maintain a steady voltage until they have delivered all their energy.
Most silver oxide batteries are flat, round button cells that do not require much silver. This option is particularly popular in Japan, where it accounts for 30% of all primary battery sales, or 64 million a year, according to Wikipedia.
However, the modern pedigree of silver oxide batteries began somewhat earlier in the 1950s. They supplied the energy for American spy satellites. They also played a role in early intercontinental ballistic missiles. Later, they found a use in the Apollo lunar module and lunar rover too.
The Modern Role of Silver Oxide Chemistry
Silver oxide batteries have quite an amazing chemistry. It may only deliver 1.2 to 1.5 volts, but it continues doing so for several thousand continuous hours. It also retains 90% of its original capacity several years after manufacture.
For chemistry, this battery uses silver oxide as its positive cathode, and zinc as its negative anode. The alkaline electrolyte is usually sodium hydroxide or potassium hydroxide.
Most modern silver oxide batteries continue to be button cells that keep the silver content relatively low, The bottom half of the button forms the graphite-infused silver oxide cathode. A plastic membrane separates this from the powdered zinc anode, dissolved in the alkaline electrolyte.
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