Not so long ago, lithium prices were soaring. It was the mineral of choice, because of its role in the shift to greener energy. Then a flood of new supply and a slump in electric vehicle sales saw prices tumble.

But lithium still has a major role to play - as shown by Rio Tinto's $9.9b acquisition this week of Arcadium Lithium.

Francis Wedin is the founder and Executive Chair of Vulcan Energy, a lithium and renewable energy company, dual listed here on the ASX and in Germany. He talks to Sean Aylmer about volatility in the lithium price, and why he sees it as a long-term play.