A battery is a device that enables chemical energy to be converted into electricity. Its scale in energy can range from nanowatt-hour to megawatt-hour. As a result, it has found very wide application in a variety of consumer markets. The history of batteries is dated back to the discovery of “animal electricity” in the 1790s, as shown in Table 1.1. There is some belief that the electrochemical battery was born with the classic frog’s vessel experiment in the first century BC with the discovery of the so-called Baghdad Battery, but it is generally accepted that the works of Luigi Galvani at the University of Bologna, Italy, and of Alessandro Volta at the University of Pavia, Italy, at the end of the eighteenth century, initiated the progress of modern electrochemistry and made batteries widely known to humanity.