The Baghdad Battery
The earliest battery known is commonly called the Baghdad Battery. It was found in an archaeological did in the 1930s and dates back to about 250 BC to AD 224. This clay vessel has an iron rod surrounded by a cylinder of copper. Tests have been done which suggest that wine or vinegar was held in the vessel. It has been suggested that these batteries were used for electroplating though that is no longer a popular theory as these batteries could not have produced enough energy for such a task. There are also no ground wires attached which would have been essential for the batteries to function. More recent speculation is that these vessels were used to hold precious documents of papyrus or vellum. Over the centuries the documents may have rotted leaving behind a slightly acidic residue.
The Voltaic Pile
In 1800 Italian physicist, Alessandro Volta, invented a battery using a stack of zinc and silver discs with brine or vinegar soaked cloth or cardboard between each pair of discs, very similar to the penny battery in this POE. While this design gave out a steady current there were a couple of problems: The first, that if the stack was too high it would squeeze out the vinegar or brine and so the battery would 'die' quickly. The second was that the metal discs tended to corrode and again shortened the life of the battery.