"Liquid Air Energy Storage systems have the potential to be a competitive local and grid scale energy storage technology. They also have the potential to facilitate the penetration of renewable energy technologies. However, there is a clear disconnect between what has been proven in literature, and what has been demonstrated in practice."
I'm very concerned with the credibility of that source based on this alone. Unpublished and/or future-dated articles are to be taken with a pile of salt.
This kind of publishing is becoming more and more common, most likely to boost the journals impact factor (average number of citation within 2 years of publication). It's sketchy but doesn't say much about the article, only the journal.
There are likely other engineering factors involved, but those efficiency figures are pretty damning on the surface.
Also from Wikipedia, the efficiency if 25% if you let the heat of liquefaction and the "cold" of vaporization go to waste, but it can be improved to 70% if you store that heat and re-inject it in the cycle.