Lithium extraction from brine through a decoupled and membrane-free electrochemical cell design

Efficient lithium extraction from natural seawater would greatly enhance
the sustainability of renewable energy technologies such as batteries.
Herein, we present a decoupled and membrane-free electrochemical cell
design that cycles lithium ions between iron phosphate electrodes. The
cathode in the brine is physically isolated from the anode in freshwater,
but they are electrochemically interconnected through a pair of
silver/silver halide redox electrodes. This design was compatible with
harsh brines featuring Mg/Li molar ratios of up to 3258 and low lithium
concentrations down to 0.15 mM to produce battery-grade lithium carbonate
with purity > 99.95%. Furthermore, the process could efficiently
harness the osmotic energy of the brines, leading to up to ca. 21.5% of
total energy savings. A pilot-scale cell with an electrode surface of
33.75 m2 realized lithium extraction from Dead Sea brine at a recovery
rate of 84.0%.