Batteries are devices that provide electrical energy stored in the form of chemical energy. The first electrochemical cell was invented in 1799 by Alessandro Volta, who generated electricity after stacking plates of copper and zinc separated by saltwater-soaked cloth. In his honor, electrical potential is measured in volts, the units seen on the billions of batteries sold each year for consumer electronics, electric vehicles, renewable energy systems, and more.
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To achieve a more stable, nonreactive state, many elements in nature are reactive and will seek to lose electrons via oxidation or gain electrons through reduction reactions. By pairing an oxidizing chemical with a reducing chemical in a battery, electrons will naturally flow between them, producing an electric current.
Experiments by Luigi Galvani on exposed frog leg nerves showed activity when they were hung from iron railings and brass hooks, suggesting the existence of "animal electricity" that discharged when connected to metals. Alessandro Volta's voltaic pile, which stacked metals with an inorganic electrolyte, showed that electricity originates from chemical reactions.
Initially a side project that became a priority due to the 1973 oil crisis, the battery's flammability risks and manufacturing challenges, along with the waning crisis, led the company to shut down its battery program. Other researchers would gradually improve upon published prototype designs in the next decade.
The lithium cathode includes nickel to increase energy storage per unit volume, as well as cobalt and manganese as stabilizing agents. Anodes are composed entirely of graphite, with aluminum and copper composing the current collectors for the cathode and anode, respectively. The battery is enclosed in a steel casing.
During charge cycles, small chemical deposits gradually form a film on the electrodes where they make contact with the electrolyte, trapping ions that would otherwise facilitate the flow of electricity. Mechanical degradation from electrode wear and electrical shorting from structural instability can also reduce battery capacity.
Charging regularly in smaller amounts while keeping a battery between 30% and 80% helps maintain lower voltage levels, preventing long-term damage. Some devices continue to draw power when at 100%, which can cause tiny charge cycles and generate heat that degrades a battery's capacity.
After a prototype cell was presented to executives in 1987, Sony repurposed its roll-to-roll manufacturing equipment for film to make lithium-ion batteries from rolled sheets of metal and electrolytes. The company popularized the term "lithium-ion" when including it in its Handycam advertising in 1991.
Lead-acid batteries used in combustion vehicles are resilient to temperature extremes, low-cost, and provide high surge current, which is needed for initial ignition. Alkaline batteries, including AA, AAA, and B, have long shelf lives and supply the low, steady power required for electronics with minimal demand fluctuations.
Inside Contemporary Amperex Technology Limited's facility, China's largest EV battery manufacturer uses slurry mixing, "jelly rolling," electrolyte injection, and other techniques and equipment to transform raw metals such as lithium and magnesium into approximately 2.2 million electrochemical cells daily.
Improper battery disposal can lead to fires and the leaching of harmful chemicals and toxic materials into local soil and water systems. Although many batteries contain metals that can be recycled with less energy than it takes to produce them, variability in regulations across municipalities and states can complicate efforts. (Some readers may experience a paywall.)
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