We described how the chemistry works in a battery in our previous post, and we link to that article below. We left the story at a point where the electrodes and electrolyte are almost primed and ready to go. However, today we are going to explore standard potentials for half reactions in batteries, before we continue with our main theme.
What Are Standard Potentials for Half Reactions in Batteries?
The Australian Academy of Science posted a neat explanation of this remarkable phenomenon that makes batteries possible. We call the exchange of electrons between electrodes a redox reaction. During this process one half of the reaction occurs at the anode, but the other half at the cathode.
Now redox is short for reduction-oxidation. Those two ‘half reactions’ control battery performance as follows:
- The ‘reduction’ half-reaction occurs at the cathode which attracts the electrons.
- While the ‘oxidization’ half-reaction occurs at the anode which surrenders them.
Standard potentials for half reactions are a measure of the ability of the cathode and anode to either attract, or surrender the electrons. Or, if you like as the Australian Academy of Science explains, which one will win the tug of war?
How Varying Standard Potentials Make the Difference
It follows there has to be a difference between these standard potentials, for the electrons to flow. Or if you like, one tug of war team must be stronger than the other at that particular moment. This implies using different materials for cathodes and anodes.
The negative anode ‘possesses’ the electrons at the beginning of the life of a battery. It therefore makes sense for the positive cathode to have a stronger standard potential to kick start the process. We’ll be back in our next post with more insider views of the secret life of batteries you may not know.
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