The section of the presentation on lithium touched a ludicrous tone when Musk said lithium is everywhere and extractable for cheap using table salt. Lithium is everywhere, but in tiny unrecoverable quantities, kind of like manganese or zinc or nickel or twenty other metals.
Standard Lithium is producing lithium chloride from brine at their pilot plant in North Carolina, without an intermediate sulfate so far as I can glean. They recently shipped 40 tonnes of Li Cl produced in their plant to be processed to lithium carbonate, half using conventional processes and half using their own novel process. Their LiCl process is an invention of chemistry geeks at UBC who I am sure considered using sodium chloride but it just ain't that simple Elon. The lithium for battery metals industry is already littered with failed attempts at low cost direct extraction from low grade sources. It is not credible that Tesla has the magic table salt key for extraction of low grade lithium from clay. If they did Tesla wouldn't have gone to great lengths to lock in long term lithium supply from existing conventional sources.
To be sure there is lots of scope for new processes in lithium extraction, especially to produce battery grade. The EV industry requirements are new and exacting. the lithium industry production worldwide is tiny, tiny, about $3 billion total and there has been little investment in extraction innovation. Tesla might come up with something novel that is viable, but others are farther ahead in that quest.