I can understand that voltage is electrostatic potential difference, with electrostatic potential being the electrostatic potential energy over the charge, but where does the electrostatic potential energy come from? Where are all the joules coming from?

Also, could you split a battery in two pieces so that one end is the positive terminal, and the other end is the negative terminal? Would the battery still work? Does current really have to go back to the origin in order to form a circuit?