As space expands,it releases stored up gravitational potential energy,which converts into intrinsic energy that fills the created volume?

Nonsense. Space does not expand at all. The idea that it does comes from the original misinterpretation of galactic redshifts as being a doppler effect when, in reality, they are a scattering effect. The galaxies are not generally receding from each other. Their light simply loses energy through it's interaction with the molecular hydrogen that fills intergalactic space (see source).

If space expanded, as well as stretching out the energy of light radially causing distant galaxies to appear redshifted, it would stretch it out transversely causing a reduction in their surface brightnesses. This is not what we observe:
http://www.sci-news.com/astronomy/science-universe-not-expanding-01940.html

Expanding space would also stretch out the light curves of quasars (their oscillation in luminosity). No sign of this either:
http://phys.org/news190027752.html

There never was a Big Bang. This documentary may enlighten you:
https://www.youtube.com/watch?v=IFFl9S39CTM

"As space expands, it releases stored up gravitational potential energy,"

False. Expansion only occurs between unbound systems, so there is no potential gain, when the objects are already "infinitely" far apart.

"which converts into intrinsic energy that fills the created volume?"

Nope.

"Does it mean then that this potential energy is infinite as universe expands more and more without limit (appearing more and more of these energies without limit)?"

No, finite contents, finite past, finite size today, finite future.