Carbon–Mineral Slurry Electrodes for Energy-Efficient Lithium Leaching from Low-Grade Clay Feedstocks

Lithium extraction from clay deposits is typically hampered
by
low lithium grades and the high capital and energy demands of conventional
processing. We report an ambient temperature electrochemical leaching
method that bypasses high-temperature roasting and concentrated-acid
leaching, directly liberating 93% of lithium from low-grade hectorite
in 24 h at 1 V, with 77% Faradaic efficiency, an energy intensity
of 3.91 MWh/t lithium carbonate equivalent (LCE). Utilizing a carbon–mineral
composite slurry electrode strategy we achieve electron-driven lattice
deconstruction through iron oxidation coupled with proton uptake to
drive lithium deintercalation, offering a new strategy for low-temperature
critical-metal recovery. A preliminary cost analysis highlights pathways
to achieving cost intensities below $3000/t LCE. Challenges remain
in improving current density, extraction kinetics, and demonstrating
process scalability, however, this work establishes a foundation for
effective electrochemical lithium extraction from abundant but previously
uneconomical clay deposits.