[merrymoccasin]

I worked for a vanadium flow battery startup which went out of business. Vanadium provides a higher degree of safety due to the chemistry not being flammable. The chemistry also cycles (charges and discharges) without degradation in energy storage capacity. However, vanadium flow batteries are far less energy dense, have moving parts (pumps), and a poor track record of reliability. There was a lot of interest in vanadium flow batteries when Li-Ion was way more expensive, but now that prices have plummeted (and will continue to do so) I don't see much of a future outside of certain applications.