Battery

Batteries are devices that store electrical energy in chemical form. Many different types of batteries are produced for a wide variety of applications, from storing solar power for satellites in space to powering heart pacemakers fitted inside people's chests.

All batteries contain one or more cells. A cell has three main parts: a positive electrode (terminal), a negative electrode, and a liquid or solid separating them called the electrolyte. When a battery is connected to an electric circuit, a chemical reaction takes place in the electrolyte causing ions (in this case, atoms with a positive electrical charge) to flow through it one way, with electrons (particles with a negative charge) flowing through the outer circuit in the other direction. This movement of electric charge makes an electric current flow through the cell and through the circuit it is connected to.