Lucy (2014), Luc Besson
The tagline: “the average person uses 10% of their brain capacity…” is an old urban legend. ”Neurologist Barry Gordon describes the myth as laughably false, adding, we use virtually every part of the brain, and that [most of] the brain is active almost all the time” (wikipedia).
We use every part of our brain, but some people (like Einstein) seem to use it more efficiently than others. So, in a sci-fi film, this is always possible to imagine some trick to improve the brain. I don’t know exactly how this is presented in the film.
According to the reviews (like this one), Lucy seems more silly than brilliant sci-fi. Luc Besson usually films well, visually, even when his scripts are weaker, so, with Scarlett Johansson as the lead, maybe this is entertaining.
Limitless (2011) is a good film on a similar theme.