TABLE OF CONTENTS In an electrolytic cell, an electric current is passed from an electronic conductor through one or several ionic conductors (electrolytes) back into a second electronic conductor. The circuit is closed outside of the cell through various electronic conductors, typically including a power supply and a current measuring device. The junctions between the electronic and ionic conductors are called electrodes, namely cathodes and anodes depending on the direction of current flow: at the cathode, electrons are transferred from the electronic conductor to some component of the electrolyte causing the discharge of some positive ion (cation) or the generation of a negative ion and also the reduction of some component of the electrolyte. As a common example, the transfer of an electron from the cathode to a water molecule causes the formation of an OH ? ion and a hydrogen atom. Two of these hydrogen atoms will then combine to form a hydrogen molecule. The opposite happens at the anode: in a typical case, a chloride ion transfers its extra electron to the anode and is converted to a chlorine atom. It should be noted that the terms "anode" and "cathode" indicate the direction of current flow and not the polarity: in a cell that consumes electric power, such as in NaCl electrolysis, the anode is positive; and in a cell that generates electric power, such as a fuel cell, it is negative. In a rechargeable battery, the electrodes switch function between charge and discharge.
