In situ micro-nano bubbles for enhanced and regenerative lithium extraction from salt lake brines

The sustainable recovery of lithium (Li⁺) from salt lake brines is critical to advancing the global transition toward low carbon energy technologies. However, Li⁺ selective sorbents such as Li-Al layered double hydroxides (LiAl-LDH) often exhibit limited adsorption capacity and poor regenerability due to electrostatic ion trapping and progressive structural degradation during repeated cycles. Here, we propose an in situ micro-nano bubbles (MNBs) activation strategy that induces a reversible crystalline to amorphous transition in LiAl-LDH, dynamically regulating interfacial charge to achieve highly efficient and durable Li⁺ extraction. The in situ generation and collapse of MNBs induce a dynamic 8.23% expansion in the interlayer spacing of LiAl-LDH, while the increased negative charge at the MNBs interface facilitates Li⁺ adsorption, resulting in a 45.3% (6.53 mg/g to 9.49 mg/g) increase in adsorption capacity. During desorption, MNBs weaken electrostatic interactions, enhancing Li⁺ desorption efficiency by approximately 25.4% (3.86 mg/g to 4.84 mg/g). Ansys Fluent simulations identify pressure and solubility gradients as the driving forces, while density functional theory (DFT) calculations reveal improved Li⁺ adsorption energies and more uniform charge distribution. Validation with four representative brine compositions at a 5000 t·y⁻¹ Li₂CO₃ production scale demonstrates a 31.5% reduction in sorbent usage (150 t to 102.8 t), a 31.5% decrease in water consumption (720 000 m³ to 493 200 m³), and annual cost savings of US$714,000 per year. This investigation presents a scalable and environmentally benign pathway for the high-efficiency extraction of lithium.