You're not going to get anywhere with this debate, because the root source, the original DB manga, never qualifies what it means by "infinite energy" nor is the matter ever discussed in-depth as far as pertains to Cell.

However, before Goku gives up and hands Cell the Senzu, after blowing Cell's head off, Goku thinks and then directly states to Cell that Cell's Ki got lower as a result of Goku's attack. This heavily implies that Cell's energy is NOT infinite or at least that Goku can permanently damage him. On page 87 of my translation of Volume (Tankobon) 34, Cell even says himself to Goku that he (Cell) has lost strength, in attempt to goad Goku into eating a Senzu and continue their fight.

Now, Cell could've been bluffing - wouldn't have been the only time he did. But if you go with the idea that characters are reliable sources of information, then Cell explicitly doesn't have infinite energy, in any sense of the word.