Commutator (electric) A commutator is a moving part of a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. It consists of a cylinder composed of multiple metal contact segments on the rotating armature of the machine.
The word equation that would represent the formation of lithium oxide from lithium metal and oxygen is: lithium + oxygen to lithium oxide. In chemical symbols, the balanced chemical equation is expressed as: Li + O2 = Li2O.
When the battery is discharged, oxygen from the air also floods through a membrane (see image, top) into the porous carbon, where it reacts with lithium ions in the electrolyte and electrons from the external circuit to form a solid lithium oxide.