Biochar-enhanced three-dimensional conductive network thick electrodes for efficient lithium extraction from salt lake brines with high Magnesia-lithium ratios.

Enhancing the kinetic performance of thick electrodes is essential for improving the efficiency of lithium extraction processes. Biochar, known for its affordability and unique three-dimensional (3D) structure, is utilized across various applications. In this study, we developed a biochar-based, 3D-conductive network thick electrode (∼20 mg cm−2) by in-situ deposition of LiFePO 4 (LFP) onto watermelon peel biomass (WB). Utilizing Density Functional Theory (DFT) calculations complemented by experimental data, we confirmed that this The thick electrode exhibits outstanding kinetic properties and a high capacity for lithium intercalation in brines, even in environments where the Magnesia-lithium ratios are significantly high. The electrode showed an impressive intercalation capacity of 30.67 mg g−1 within 10 min in a pure lithium solution. It also maintained high intercalation performance (31.17 mg g−1) in simulated brines with high Magnesia-lithium ratios. Moreover, in actual brine, it demonstrated a significant extraction capacity (23.87 mg g−1), effectively lowering the Magnesia-lithium ratio from 65 to 0.50. This breakthrough in high-conductivity thick electrode design offers new perspectives for lithium extraction technologies. The watermelon peel serves as the substrate, simultaneously supporting the in-situ loading of LFP, thereby forming an LFP/WB thick electrode exhibits high lithium absorption capacity and excellent kinetic performance in high Mg2+/Li+ ratio brine. It achieved an impressive absorption rate of 30.67 mg g−1·min−1 in 10 min and an average lithium extraction of 23.87 mg g−1 from salt lake brine. This approach effectively reduced the Mg2+/Li+ ratio from 65 to 0.50, enabling efficient lithium separation and comprehensive biological resource utilization. [Display omitted] • The comprehensive utilization of biological resources is achieved. • The low efficiency of Li + extraction with thick electrode is effectively solved. • Effectively reducing the Mg2+/Li+ ratio in low-grade brine. [ABSTRACT FROM AUTHOR]