All batteries work in the same basic way, creating the magic of electricity through the wizardry of chemical reactions. When two chemicals react to form a third compound, the individual atoms can gain, lose, or share electrons in an attempt to balance the positive and negative charges at the atomic level. Batteries pair two reactions—one that causes a loss of electrons and one that requires a gain of them—to create a flow of electrons that can be used to start cars or run cell phones. Each reaction occurs at an electrode at opposite ends of the battery.
The flow of electrons is called current, and that current is what makes things light up or spin. For electrons to flow, there needs to be a circuit, typically a wire, between the electrode that has a surplus of electrons and the one that has a need of them. The spot with the surplus of electrons is said to be negatively charged (the anode), while the electron-poor spot is positive (the cathode). One anode and one cathode make up a cell, and a battery is a collection of cells. The more cells a battery has, the higher its voltage.
Anodes and cathodes are metals or metal oxides of differing electrical potential. In addition to an anode and a cathode, a battery cell requires an electrolyte in which the anode and cathode are placed. The chemical reactions occur between the metals of the electrodes and the electrolyte. Electrolytes can be a variety of substances. Over two millennia ago, batteries were made in Mesopotamia by submerging iron and copper electrodes in a vinegar electrolyte. As the Mesopotamian civilizations weren’t known for their advanced electronics, the guess is that this was done as a novelty or in some religious ceremony. In the 1780s, Alessandro…
Get building science and energy efficiency advice, plus special offers, in your inbox.