Forbes: A Novel Vanadium Electrolyte Storage TechnologyApologies if this has been posted, it didn't hit my radar if so and is quite recent. I'm not sure that Imergy's flow cell is any more innovative than any other V-redox mfg, but it's good press.
https://www.forbes.com/sites/peterdetwiler/2014/04/30/imergy-a-novel-vanadium-electrolyte-storage-technology/