Semi-sacrificial fabrication of binder-free lithium-aluminum layered double hydroxides adsorbents for lithium extraction

Lithium aluminum layered double hydroxides (LiAl-LDHs) are by far the most mature adsorbent material for lithium extraction, but their efficiency is severely limited by the shaping process, in which the unavoidable use of binders reduces exposure of the active adsorption sites. To sidestep the shaping process, we herein innovate a direct construction strategy for LiAL-LDH using a semi-sacrificial nickel aluminum foam (NiAl-F). Based on an in-depth analysis of the transformation process, adhesive-free adsorbents effectively break through the original microgram level (μg/cm²). We demonstrated Fe³⁺ could effectively incorporate and form the binder-free LiAlFe-LDH@NiAl-F adsorbent with enhanced lithium adsorption capacity from the microgram level to 5.2 mg/g and stability of over 30 adsorption-desorption cycles. The facile and economical methodologies, including anion exchange, cation doping, and loading enhancement, point at the practical route for further optimization and scale-up toward robust lithium extraction technology.