The world’s largest demonstration plant for a new kind of renewable energy storage is up and running in the west of the China. Called liquid-air energy storage (LAES) the plant uses renewable electricity to compress air to extreme densities until it turns to liquid. It can then be rapidly released to power a turbine and discharge that green energy back into the grid.
This source says that efficiency wasn’t published, but at least it discusses some typical values
https://climatesolutions.news/spotlight/china-liquid-air-energy-storage-golmud