Thick electrodes greatly enhance lithium extraction capacity. However, with the increase of active substances loading, the traditional thick electrodes are more hydrophobic, severely limiting the utilization of active substances. Hence, a sulfonation process to functionalize thick electrodes was applied to enhance their wettability (~45 mg·cm⁻¹) in brine. Experimental and theoretical results show that the lithium extraction capacity of thick electrodes can be significantly improved by enhancing the electrodes hydrophilicity. At 0.8 V, the S-PVDF electrode's capacity for lithium extraction in simulated brine (41.72 mg·g⁻¹) significantly surpassed the PVDF electrode (35.72 mg·g⁻¹), and it also performed well in actual brine (28.8 mg·g⁻¹). The Mg²⁺/Li⁺ ratio in actual brine dropped from 65 to 0.37, achieving effective magnesia‑lithium separation. This method offers a novel approach to developing high-efficiency lithium extraction thick electrodes.

Cost-effective and efficient lithium extraction technology is vital to foster the growth of lithium industry. This paper proposed a novel approach for the high value utilization of spent LiFePO₄ (S-LiFePO₄) in the field of lithium extraction from salt lakes was proposed using spent LiFePO₄ (S-LiFePO₄) as raw material. The anode, made from spent LiFePO₄, is prepared via a sintering process, while FePO₄, obtained through chemical oxidation, is used as the cathode. Compared with commercial LiFePO₄, this system not only reduces the cost but also greatly shortens the preparation time of FePO₄ (only about 10min is required). And the electrochemical extraction system had a favorable lithium extraction capacity (29.25 mg/g) from actual brine, reducing the Mg/Li ratio from 61.4 to 0.8. This study not only achieved the low-cost preparation of electrode materials and facilitated the large-scale implementation of this process, but also proposed a high-value comprehensive utilization strategy for lithium-ion batteries recycling.

Improving the kinetic performance of thick electrodes is key to enhancing lithium extraction from salt lakes. Nano-melamine foam (MF), known for its unique porous structure, is ideal for building a three-dimensional (3D) conductive network, thereby boosting electrode kinetics. In our study, we developed a thick electrode (20 mg·g−1) with a 3D-conductive network by in-situ growing LiFePO4 (LFP) onto a nanoscale MF substrate. This electrode exhibited superior kinetic performance and a high lithium adsorption capacity in brine, achieving up to 32.8 mg·g−1 in just 10 min. Remarkably, even in simulated brine with a high Mg2+/Li+ ratio, it maintained an average coulomb efficiency of 62 %, significantly lowering the Mg2+/Li+ ratio from 65.6 to 0.47. It also showed exceptional stability in actual brine, maintaining an average coulomb efficiency of about 56.6 %. Our development of this high conductivity, thick electrode provides new insights into efficient lithium extraction methods.