Where does the electricity come out of a battery?

Answer 1

The electricity flows out the negative terminal, through the work load, and back into the positive terminal. It consists of negative electrons. In the early days of electrical experimenting, the scientists had to guess as to whether the electric flow was positive particles or negative particles. They had no way to test. They guessed positive. They were wrong. So we have inherited a definition of current as positive fluid going from positive terminal (outside the battery now) to negative terminal. We have stayed with that convention even though we know better today. It makes no difference at the circuit level. Positive particles flowing rightward has the same effect as negative particles flowing leftward. Of course, if you are designing batteries, you will want to know what flows which way.