Quote from: scientizscht on 26/07/2018 13:55:34

I still don't understand fully.

So both metals are neutral, but have tendency to release or gain electrons.

While it is possible to use two neutral metals with wildly different electronegativities (like aluminum and palladium), this is not always the case (see my previous post in this thread).

Quote from: scientizscht on 26/07/2018 13:55:34

When connected together, their pairing tendency moves electrons from one to the other.

For the electrons to move, we need to provide a path, which we do via? What are the necessary characteristics of that path? Doesn't simple water do?

A wire provides the path for electrons to move. Water (or other highly polar liquids, or ionomers etc.) allow ions to move.

Quote from: scientizscht on 26/07/2018 13:55:34

When electrons move, they generate positive and negative charged metals that create a potential difference.

What happens as the electrons move apart from charging the metals? So that the battery capacity drops yet the voltage stays the same?

If ions were not allowed to flow then yes, the there might be a very brief spike in current when the terminals are connected by a wire, but the voltage would drop to zero when the batteries internal electric field cancels out the inherent electron affinities of the different metals (and/or ions). But, when ions are able to move within the battery, their motion will keep the internal electric field very small (zero internal field, for perfect ion mobility), allowing the voltage of the battery to remain constant until one end runs out of electrons to give, or the other end runs out of space to accept electrons, or there are no more mobile ions. (to first approximation--the voltage will actually decrease slightly as one or more of the limits is approached, rather than suddenly dropping from 100% to 0%--but this is a complication you can ignore until you feel more comfortable with the "ideal" case. When ready for this complication, you can read about it here: https://en.wikipedia.org/wiki/Nernst_equation)

Very interesting.

So to sum up the principles:
1) the electromotive force for a battery to work is the electronegativity difference of two materials, which we can call them primary.
2) it is also needed to have a wire to allow electrons to transfer and produce work
3) it is also needed to have a SECONDARY connection between the materials AND a pool of positive and negative ions. This is because we need to prevent charging of the primary materials as their electrons move. If this charging is not prevented through the use of a third material's ions in a solution that connects the primary materials, the battery simply would stop to work.
4) the capacity of the battery drops as the battery is in use and the electrons flow from one primary material to the other. The capacity depends on the amount of materials that are contained in the electron donator material and the positive holes/gaps in the electron acceptor material.
5) the flow of the third material's ions in the solution which bridges both the primary materials, does not affect the electronegativity differential of the primary materials. This is only affected by the electrons available in the donator and the gaps available in the acceptor. The solution bridge's ipns only prevent build up of macroscopic charge of the primary materials that would oppose the electrons flow.
6) I suppose we need to supply the adequate amount of ionic solution so that there's protection from static charge build up throughout the life of the battery.

Is the above a comprehensive summary of battery operation?