Does the negative terminal of a battery have a higher concentration of electrons? I'm 15 and  recently started electronics and I just had a question about batteries.
According to a video  I watched by "The Engineering Mindset", a battery creates potential difference by accumulating more electrons on the negative plate. Therefore the more electrons that accumulate on the negative plate, the higher the battery voltage.
Could someone tell me if this is correct please?
 A: Yes it is true.
When electrons move from positive terminal to negative terminal,we get a positive charge on positive charge on the positive terminal as now there are more protons here than electrons and vice versa. This movement is caused by some internal battery mechanism which generates a force to do so.
Net result is positive charge on positive terminal and negative charge on negative terminal.This charge separation further creates an electric field opposite to that Force by battery mechanism.This 'created' field due to charge separation is the actual cause of Voltage.

P.S. This is the best I could do without going into much Physics.If you want any clarification comment below.
A: it is the difference of the two electrodes what makes the voltage, and the possibility of the medium in between to carry positive and negative ions makes the batterie work. but yes there is an accumulation of e- at one end and lack of them at the other end, Maybe you look up, how a batterie works in wikipedia,
f.e. https://en.wikipedia.org/wiki/Galvanic_cell
if you know some chemistry you can understand it better. I don't know if your video is correct, at least it is an oversimplification,
