Even when talking about RO, you'd think diverting all or part of the brine water for evaporation would reduce the cost of extraction. You'd have water with more concentrated minerals which would give you a higher yield per evaporation cycle.

Also, it'd be nice if we could bring back magnesium extraction from ocean water.

The headline should be "thing can extract lithium from sea water at 50% efficiency. It also produces potable water."