Enhanced lithium recovery and recycling using morphology-controlled LiAl-LDH multilayers

Layered double hydroxide (LDH) multilayers were fabricated on aluminum metal substrates to separate lithium cations in aqueous lithium resources. LiAl-LDH crystal layers were grown via aluminum oxidation in lithium salt solutions with urea, demonstrating that larger crystals have higher lithium adsorption capacities, depending on anions and their concentrations. Acetate anions facilitated larger LiAl-LDH crystal growth and promoted superior lithium adsorption across a broader concentration range, specifically inducing fine LiAl-LDH powder formation on LDH films in high acetate concentration. This resulted in approximately three times more lithium adsorption than other anions, with 134 μg Li/cm² Al substrate. Controlling the morphology during lithium desorption was critical for enhancing re-adsorption, as structural adjustments led to a more exposed surface and increased number of active sites. Two distinct morphologies of delithiated LiAl-LDH were developed to construct multilayer nanostructures on aluminum substrates, effectively improving lithium recovery during subsequent cycles. This method offers an efficient and sustainable approach for lithium extraction and recycling from high-concentration lithium resources without the need for complicated chemical processes, such as particle separation or membrane application.