The most favorable answer in the realm of the correct that you could get on this is "it might not be completely impossible to get free energy someday. But it probably is." There are some theories that offer a possibility of free energy, but they are generally regarded as crackpot theories. However, since the very question you're asking is about free energy, and these crackpot theories are rejected most stringently on the grounds that they offer a possibility of free energy, it turns out that this is actually a question-begging response.
So, let's talk about our direct reasons for believing in the conservation of energy: We have never seen it violated. Wow, that's impressive, right? Well, a little less impressive when you actually peer into the history of science and notice that it is actually more like "every time we've seen it violated, we've been able to rework our models to account for it within an energy-conservation paradigm. Still, though, really impressive. The worst you could say about these models, actually, is "well, okay, clearly there's some sort of conservation principle in play, but why dig in on energy?" And the answer is that energy is really not a rigorously defined concept. It's an abstract thing that falls out of the mathematics we apply to the events we observe.
So, it turns out that what you want isn't really free energy, but rather free labor. You want your phone to function for you without you having to recharge or replace the battery. We're a lot more likely to get that in the near future than free energy. Between incremental electronic refinements, the possibility of a room temperature superconductor, and the popularization of induction charging, you might wind up with a phone you needn't ever charge within the next few years. But it won't be free energy.
Even the crackpot theories that say we'll someday get free energy devices out of the zero point energy field don't really deny conservation of energy: what they mean is we'll extract energy from outside our local universe. (Some even worry that using this energy would hasten a vacuum collapse of our universe.) But they aren't doing particularly well. There is ongoing research, but it isn't going to put a device in your pocket in five years. (https://en.wikipedia.org/wiki/Zero-point_energy#Utilization_controversy)