Prof. Huamin Zhang was invited by Nature and interviewed by Nature Reporter to consult on their Feature Article (Nature, 2014, 507, 26). He also was invited by the Subject Editor of Nature to write an article in the form of Correspondence for Feature Article. In the article, he pointed out that vanadium flow batteries are an attractive commercial proposition because they are safe and environmentally friendly, use recyclable electrolytes, have a long cycle life (around 13,000 cycles) and last for more than 15 years. Their cost is not as prohibitive as believed (Nature, 2014, 508, 319).

At present, the estimated cost of US$1,000 per kilowatt-hour, which is indeed high, but this applies to the world's largest vanadium flow battery system and includes materials, manufacture, the control system, transportation, installation and maintenance. The cost of a system that is one-fifth of this size is $600 per kilowatt-hour, which is expected to drop to $400 per kilowatt-hour within the next 2–3 years.

After two years of innovation and development, the current density of vanadium flow battery stacks from the Rongke Power Company in Dalian, China, has risen from 80 to 120 milliamps per square centimeter.

Although the cost of vanadium itself is relatively high, these flow batteries hold promise as large-scale energy-storage devices.