Tailored Lmo@Cof Composite Electrodes for Direct Electrochemical Lithium Extraction from High-Temperature Brines

Abstract

A composite electrode material LiMn2O4-Pyr-2D was designed by combining the covalent organic frameworks (COFs) Pyr-2D with LiMn2O4(LMO). Pyridine(Pyr) was used to form a planar and conjugated structure, which enabled the formation of ordered and stable molecular building blocks with regular pores and uniform element distribution. The structure is reduced the rate of Mn dissolution and Jahn-Teller effect-induced structural collapse of LMO under high temperatures, significantly improving the high-temperature resistance and lithium extraction efficiency of LiMn2O4 in geothermal brine. Furthermore, the fast ion diffusion rate at high temperatures was utilized to improve the lithium extraction efficiency. The results show that LiMn2O4-Pyr-2D achieved an initial discharge capacity of 154.00 mAh/g in a LiCl solution at 60 ℃, and a capacity retention rate of 93.32% after 15 cycles of lithium extraction in geothermal water from Tibet at 60 ℃. The unit energy consumption was 0.46 Wh/mol with an extraction capacity was 47.03 mmol/g. This approach opens a new way for electrochemical lithium extraction from high-temperature brine with high efficiency.

Keywords: Electrochemical lithium extraction, 2D-COFs, Composite electrode material, Resistance to heat, Separation efficiency