Short answers, pulled from the story.
Benjamin Franklin coined the word battery in 1749 to describe a set of linked Leyden jar capacitors. He borrowed the military term for weapons functioning together to explain how multiplying holding vessels stored a stronger charge. This was not the electrochemical battery we know today, but it established the conceptual framework for combining individual units to create a more powerful source of electricity.
Italian physicist Alessandro Volta constructed the first electrochemical battery, known as the voltaic pile, in 1800. The device was a stack of copper and zinc plates separated by brine-soaked paper disks. Volta believed his invention was an inexhaustible source of energy and viewed the corrosion at the electrodes as a mere nuisance rather than an unavoidable consequence of operation.
Wet cells use liquid electrolytes and were prone to leakage and spillage if not handled correctly. Dry cell batteries replaced the liquid electrolyte with a paste near the end of the nineteenth century, making portable electrical devices practical for the first time. This transition allowed batteries to be used in a wide variety of applications, from the A battery that powered filaments in vacuum tube devices to the B battery that provided plate voltage.
Secondary batteries, also known as rechargeable batteries, can be discharged and recharged multiple times by applying an electric current that reverses the chemical reactions that occur during discharge. The oldest form of rechargeable battery is the lead-acid battery, widely used in automotive and boating applications. Modern developments include nickel-cadmium, nickel-metal hydride, and lithium-ion cells, with lithium-ion having by far the highest share of the dry cell rechargeable market.
About 179,000 tons of the nearly three billion batteries purchased annually in the United States end up in landfills across the country. Many types of batteries employ toxic materials such as lead, mercury, and cadmium as an electrode or electrolyte, and when each battery reaches end of life it must be disposed of to prevent environmental damage. In 1996, the Mercury-Containing and Rechargeable Battery Management Act banned the sale of mercury-containing batteries in the United States, while the European Union's Battery Directive requires all batteries to be marked with the collection symbol and promotes research on improved battery recycling methods.
In 2023, the world's largest battery was built in South Australia by Tesla, capable of storing 129 megawatt-hours of electricity. Another large battery in Hebei Province, China, built in 2013, could store 36 megawatt-hours of electricity at a cost of 500 million dollars. A battery composed of nickel-cadmium cells in Fairbanks, Alaska, covered an area bigger than a football pitch and weighed 1,300 tonnes, manufactured by ABB to provide backup power in the event of a blackout.