It’s a debate that matters for Australia, which exported $20 billion worth of lithium last year and now relies on the lightest metal to be its fifth most lucrative commodity export behind iron ore, coal, gold and liquefied natural gas (LNG). And it’s a debate that is fixated on comparisons to the shale oil and gas revolution. “Production of lithium from brine water, if you think about what is required to do that, is really an extension of a lot of the current capabilities that we have,” said ExxonMobil chief executive Darren Woods, during an investor call last month. When...