If I correctly understood how batteries work: once they are connected to a circuit, there is a chemical reaction inside that separates electrons from atoms, moving the positive ions to one terminal and the electrons to the other terminal. When the battery is removed, the process stops but some positive charges remain on the positive rod (terminal) and some negative charges on the negative terminal.
If there are charges left in any of the terminals, why approaching one terminal from a piece of paper or an electroscope doesn't show any kind of static electricity?