Batteries are in use everywhere today. But where did they come from? The first true battery was developed in the 1790s by Alessandro Volta (for whom the SI unit Volt is named). Called the Voltaic Pile, it consisted of an alternating stack of zinc and copper plates, with salt water soaked cloth between each piece of metal. It was the first device that gave a consistent electrical flow; other sources of electrical energy before this gave an inconsistent, bursty electricity. It also had the same behavior we see in batteries today: when connected to a circuit it discharges its energy, when not connected its energy is stored for later use.
In the 1830s John Frederic Daniell developed a battery known as the Daniell cell. One of the problems with Volta's battery was that it used salt water as an intermediary through which ions and current would flow. Current flow through water is called electrolysis and breaks the H20 water molecules into hydrogen and oxygen gas. The hydrogen gas resisted electrical flow and once there was too much of it, the battery stopped functioning. Daniell's new cell had a second chemical dissolved in the water that would consume the hydrogen as it was produced, significantly increasing the lifespan of the battery. Finally there existed a battery useful enough to leave the laboratory of scientists and go to work in the real world.