“According to the researchers, the cell will probably need $5 of electricity to extract 1 kilogram of lithium from seawater.”
Seawater holds 5,000 times more lithium than land does, at 0.2 parts per million. The KAUST cell is a lab prototype, and “probably” is carrying that $5 figure. The economics also count on selling the hydrogen and chlorine it makes. Lab results that cheap rarely survive contact with a factory.