Eco-friendly extraction of magnesium and lithium from salt lake brine for lithium-ion battery

Abstract

The composition of salt lake brine is complex, and the physical and chemical properties of Mg and Li are very close to each other, which is difficult to separate. In this paper, a new type of nanomaterial is developed based on the salt lake brine, and the Qinghai salt lake in China is used as the model. The solar evaporation-acid leaching-diaphragm electrolytic doping strategy is used to successfully separate Li and Mg. A composite metal self-supporting material is constructed during the electrodeposition process, and finally prepared MgZnCe(OH)8 and its oxide MgZnCeO4 are used as anode materials, and LiPF6 is used as electrolyte. Electrochemical tests show that at a current density of 200 mA/g, the initial charge and discharge capacity are 38.71 (274.33) and 76.41 (138.78) mAh/g, but after many cycles, the capacity is steadily increased, the charge and discharge capacity is almost equal, the coulombic efficiency is as high as 100%. In particular, the MgZnCeO4 negative electrode has an increase of nearly 3.41 (1.45) times compared with the first cycle of charge and discharge capacity after 3000 cycles. This excellent lithium storage performance is attributed to the macroscopic design of the composite metal supporting negative electrode. The special alloying reaction, Mg2+ substitution reaction, more stable spatial structure and smooth Li+ transmission channel can effectively improve the volume change, and also accelerate the lithium/dilithium dynamics.