We don't know what happens at quantum/chemistry level at all times why a battery does what it does. Ohm's law however, doesn't give a darn about that. As long as we know the voltages at two ends, we know current flows and the direction of it. I have given you the method by which we can compute all of this.

Put a lightbulb on a battery and see it go out eventually. You can measure that time without again, knowing a darn thing about what is exactly going on from microsecond to microsecond in the battery. These are macro effects we care about as users of power.

Now if you want to design better batteries, then you sign up to know more. But even there as I mentioned, there are significant barriers to what we know and as a result, simple experimentation is made by for example introducing rare items from periodic table to see if longevity, charging ability, charge availability, voltage, etc. is improved or not.

For your part you seem to have invented an issue, a barrier to flow of electricity, which you say you don't know what it is. Yet insist on someone explaining it to you. I don't know how to explain concepts that you have conceived. I can only explain how in real life the batteries equalize each other as this is fundamental to building battery packs (two of which I have built to power my EV Quad and RV). And here, all we care about is practical aspects of how the system works. No one cares if there are femtovolt differences causing femtoamp current flow. Maybe you care about .01 degree temp in your room, but I don't. :)

I am afraid of explaining more as there seems to be this barrage of disagreement and disapproval in return. Hopefully someone else can provide a satisfactory response.