Imagine a parking lot and a grocery store. Cars can come in and out, there's spaces for each little car, and it's purpose is to hold cars. The acid intermediary is that parking lot. The metal attractor is that grocery store. Cars are electrons. When there's lots of empty spaces it's easy for cars to pull in, so as long as the connecting road is open you can fill up the parking lots, when it's full the opposite is easier. The parking lot itself doesn't change no matter how many cars are in parking spots, so cars can come and go freely as long as the connecting roads are open.

This is a cool question!

Firstly, not all batteries are rechargeable, as we all know. Single charge batteries use a one-time chemical reaction that physically changes the internal structure of whatever is in the battery to produce electricity via chemical reaction. Rechargeable ones work in such a way because the chemical reaction that occurs within the battery that is reversible. Basically, the electrochemicals within the battery store potential energy, but are locked into their energy storing state by electrons simply having nowhere to go. When you connect the battery to something you’d like to power, it allows the chemical reaction to begin, which releases electrons thus allowing them to flow to whatever it is you are providing power to. Once the internal chemical reaction has completed, the battery no longer has power. To recharge it, you must reset the chemical reaction, and this is done by sending electrons back into the battery. The electrons find their way back in almost perfectly, which is why rechargeable batteries have longer lives cumulatively than single use batteries, but rechargeable batteries slowly lose efficiency over time.