The voltaic pile is an early form of primary battery, consisting of alternate pairs of dissimilar metal discs with moistened pads between pairs. It was the first electrochemical battery that could continuously provide an electric current to a circuit.
The Italian scientist Alessandro Giuseppe Antonio Anastasio Volta invented the voltaic pile in 1800 in an effort to disprove the “animal electricity” reported by his contemporary, Luigi Galvani (another Italian scientist). Galvani discovered that a dead frog’s legs would move if they were touched by brass electrodes that were connected to an iron plate; thus he concluded that it was because of the presence of “animal electricity” within the frog that allowed it to supposedly reanimate. However, Volta believed that was not the case and that it was because of the difference in metals which generated the electricity in the frog’s legs. To prove his theory, Volta created the first electrochemical battery. Here is a labelled diagram based on his original “pile”: