īenjamin Franklin first used the term "battery" in 1749 when he was doing experiments with electricity using a set of linked Leyden jar capacitors. His assumption was that it was used for electroplating, but later theories suggest it may have been a medical device used for electrotherapy. In the 1930s, the director of the Bagdad Museum and Iraq Antiquities Department Wilhelm König reported the discovery of the Baghdad battery, a first century device consisting of a ceramic pot, copper, and iron. Italian physicist Alessandro Volta demonstrating his pile to French emperor Napoleon Bonaparte In automobiles, this is somewhat offset by the higher efficiency of electric motors in converting electrical energy to mechanical work, compared to combustion engines. Batteries have much lower specific energy (energy per unit mass) than common fuels such as gasoline. Examples include the lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics such as laptops and mobile phones.īatteries come in many shapes and sizes, from miniature cells used to power hearing aids and wristwatches to, at the largest extreme, huge battery banks the size of rooms that provide standby or emergency power for telephone exchanges and computer data centers. Secondary (rechargeable) batteries can be discharged and recharged multiple times using an applied electric current the original composition of the electrodes can be restored by reverse current. Primary (single-use or "disposable") batteries are used once and discarded, as the electrode materials are irreversibly changed during discharge a common example is the alkaline battery used for flashlights and a multitude of portable electronic devices. Historically the term "battery" specifically referred to a device composed of multiple cells however, the usage has evolved to include devices composed of a single cell. When a battery is connected to an external electric load, a redox reaction converts high-energy reactants to lower-energy products, and the free-energy difference is delivered to the external circuit as electrical energy. The terminal marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal. When a battery is supplying power, its positive terminal is the cathode and its negative terminal is the anode. It originated as a schematic drawing of the earliest type of battery, a voltaic pile.Ī battery is a source of electric power consisting of one or more electrochemical cells with external connections for powering electrical devices. ![]() The symbol for a battery in a circuit diagram. ![]() Various cells and batteries (top left to bottom right): two AA, one D, one handheld ham radio battery, two 9-volt (PP3), two AAA, one C, one camcorder battery, one cordless phone batteryĮlectrochemical reactions, Electromotive force
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