I’m having a difficult time figuring this out since oxidation always occurs at the anode, and this would be where electrons are produced.
Is it this: in voltaic cells, the reaction is spontaneous and does not require a current. So oxidation of the element etc. occurs on its own, and electrons are produced. Because electrons move spontaneous from negative to positive, the anode (where electrons are produced) must be negative or else the electrons would be moving from positive to negative which does not make sense, unless they were forced to do this (like in an electrolytic cell)
