So in an electrical circuit you can think of the change in height of a mass as a model for voltage differences for charge. The model continues. Just as balls with positive mass tend to roll downhill, positive electric charges move from places of high potential to places with lower potential. So positive charges move under electrical forces from the positive terminal of the battery through resistors to the negative terminal. There are no negative masses, however, helium balloons in air behave a lot like negative masses.
Balloons tend to rise when gravity pulls downward.
So too, negative charges move from places with low voltage to places with higher voltage. Thus, negative electrons move outside of a battery from the negative or low voltage terminal to the positive or high voltage terminal. The metal case is lined with zinc which is attached to the negative terminal, there is a carbon rod in the center attached to the positive terminal. Between the carbon and the zinc there is a black paste made from manganese dioxide, carbon, and ammonium and zinc chlorides. In the cheapest batteries there is also a cylindrical flour and paste separator.