Definition and Components of a Battery
– A battery is a source of electric power in the form of one or more electrochemical cells.
– It consists of electrochemical cells with external connections for powering electrical devices.
– The positive terminal of a battery is the cathode, and the negative terminal is the anode.
– The negative terminal is the source of electrons that flow through an external electric circuit to the positive terminal.
– When connected to an external electric load, a redox reaction converts high-energy reactants to lower-energy products, delivering the free-energy difference as electrical energy.
Types of Batteries
– Primary (single-use or disposable) batteries are used once and then discarded.
– Secondary (rechargeable) batteries can be discharged and recharged multiple times.
– Examples of primary batteries include alkaline batteries used for flashlights and portable electronic devices.
– Examples of secondary batteries include lead-acid batteries used in vehicles and lithium-ion batteries used for laptops and mobile phones.
– Primary batteries have irreversibly changed electrode materials during discharge, while secondary batteries can restore the original electrode composition through reverse current.
Range of Battery Sizes
– Batteries come in various shapes and sizes, from miniature cells for hearing aids and wristwatches to large battery banks for standby or emergency power.
– Some battery banks are as large as rooms and provide power for telephone exchanges and computer data centers.
– Batteries generally have lower specific energy (energy per unit mass) compared to fuels like gasoline.
– However, electric motors in automobiles are more efficient in converting electrical energy to mechanical work compared to combustion engines.
– This offsets the lower specific energy of batteries in automotive applications.
History of Batteries
– The term ‘battery’ was first used by Benjamin Franklin in 1749 when experimenting with electricity using linked Leyden jar capacitors.
– Franklin grouped multiple jars into a battery to store a stronger charge and increase available power on discharge.
– Italian physicist Alessandro Volta built the first electrochemical battery, the voltaic pile, in 1800.
– Volta’s pile consisted of copper and zinc plates separated by brine-soaked paper disks, producing a steady current.
– Michael Faraday later showed that the voltage in Volta’s cells was due to chemical reactions and not an inexhaustible source of energy.
Invention and Practical Use of Batteries
– Early batteries were valuable for experimental purposes but had fluctuating voltages and couldn’t provide sustained large currents.
– British chemist John Frederic Daniell invented the practical Daniell cell in 1836.
– The Daniell cell became an industry standard and a power source for electrical telegraph networks.
– It consisted of a copper pot filled with a copper sulfate solution and a zinc electrode.
– The Daniell cell provided a stable voltage and sustained current, improving the practicality of batteries for various applications.Sources: https://en.wikipedia.org/wiki/Electric_battery
