Battery is referring to a device for making or storing electricity chemically. Electricity is a form or energy that is easy to control, convenient to use but difficult to store.
A can of petrol contains 10,000 times the energy of a car battery. Hence the difficulty in making an electric car with a good performance. Technically, a battery consists of two or more series or parallel connected galvanic cells. Frequently, however, a single cell is called a battery. (see Alkaline battery, Burglar alarm battery, Hearing aid batteries, LeClanche battery, Li-Ion batteries, Magnesium battery, NiCd, NiMh, Primary battery, Sealed lead acid batteries, Secondary battery, Watch batteries, Zinc-Air)
See also:
"Battery" is in the NAICS Code "335911"