Dual-engineered Ni-LiMn₂O₄ microsheets for sustainable lithium mining: Accelerated ion transport and robust...

The surging demand for lithium in energy storage necessitates sustainable and efficient electrochemical lithium recovery from salt lakes. Herein, we develop Ni-doped LiMn₂O₄ microsheets (LNMO-MS) via a green bio-templated synthesis that integrates 2D morphology engineering and Ni-doping using chitosan biopolymer as a structural guide. This dual modulation addresses intrinsic limitations of conventional LiMn₂O₄. Ni doping induces [MnO₆] octahedral contraction to stabilize the framework and enhance Li⁺ selectivity (Mg²⁺/Li⁺ separation factor: 401.32 at Mg²⁺/Li⁺ = 200), while the 2D architecture shortens Li⁺ diffusion paths, enabling 10-fold faster ion kinetics and improved charge transfer. In capacitive deionization (CDI), the LNMO-MS achieves a record Li⁺ adsorption capacity (4.12 mmol g^-1), with low energy consumption (1.96 Wh moL^-1 Li⁺), outperforming conventional LiMn₂O₄ electrodes. Real-world validation using Qarhan Salt Lake brine demonstrates practical viability, producing concentrated LiCl solutions (1 g L^-1 Li, Mg²⁺/Li⁺=0.13) at 8.63 Wh·mol^-1 Li⁺, while maintaining 92 % capacity retention over 200 cycles. The strategy of bio-guided 2D structuring and Ni doping establishes an energy-efficient, durable platform for selective lithium extraction, offering a sustainable solution to bridge lithium supply-demand gaps with minimized environmental footprint.