An electrical battery contains one or more electrochemical cells. Each of these cells has two electrodes, and (at least) one electrolyte according to Missouri University of Science. Two core processes, oxidation and reduction govern battery operation. Today we explain how a gain in electrons is also a reduction. While a loss of these causes oxidation.
The Gain in Electrons Occurs at the Cathode
However, this possibility is lost should the electrodes touch each other. A short circuit will release the energy as heat, and this will dissipate. Therefore, a battery requires a regulated environment in which to do its work. Good battery design achieves this by using electrodes of different materials, and separating them with an electrolyte.
This arrangement initiates a process whereby the electrons that oxidation releases at the anode electrode, can do useful work. This output occurs during a gain in electrons elsewhere, as these transfer to the cathode which consumes them during corresponding reduction.
But this process soon grinds to a halt, because there is no useful work to do inside the battery. The gain in electrons requires an external circuit between the electrodes to keep the positively-charged ions moving from anode to cathode. While negatively-charged ions move in the opposite, compensating direction.
Oxidation and Reduction in Electrochemical Batteries
Battery scientists call this transfer of electrons an oxidation-reduction reaction, or redox for short. It is the key process that distinguishes batteries from other oxidation-reduction reactions including rusting / corrosion.
This difference is possible as a result of the physical separation of the processes at the battery electrodes. And of the opportunity to harvest the energy, by passing the electrons through a suitable load in an external circuit.
Our image at the top of this article illustrates the key battery components of electrodes, electrolyte and external circuit. And also the negative and positive ions moving during the redox process, and corresponding recharging cycle.
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