Rio Tinto should buy up Arcadium Lithium, the New York-listed lithium producer which acquired Australia’s Allkem in a mega-merger this year, instead of pursuing its own efforts to build out a battery metals business, Citi brokers say.

In a note to clients, the Wall Street investment bank’s analysts said buying Arcadium – which has a market capitalisation of $US3.96 billion ($5.86 billion) – “could be a more economical option than developing its own lithium assets”.