Study On The Extraction Of Lithium By Electrochemical Method Based On LiMn₂O₄

With the rapid development of industry,the demand of global market for lithium keeps growing.The lithium extraction from brine and seawater has become the mainstream.Lithium extraction using a electrochemical method has a good application prospect due to its simple technological process,easy control without the introduction of impurity ions.Under the effect of direct current,LiMn₂O₄ electrode has good behavior of lithium deintercalation/intercalation.Besides,LiMn₂O₄ is the precursor of manganese lithium ionic sieve.In this paper,the lithium recovery process using a electrochemical method based on LiMn₂O₄ was studied.The LiMn₂O₄ electrode was prepared with LiMn₂O₄ as active substance and different materials（graphite sheet,carbon paper and carbon fiber cloth）as current collectors.The effect of voltage,temperature and coexisting ions on lithium extraction were studied in this work.The extraction capacity of Li⁺as well as the energy consumption reached the maximum at 1.2 V.The higher the temperature,the faster the extraction rate,but the greater the energy consumption.The influence of coexisting ions on lithium extraction followed the sequence:Mg²⁺>Na⁺>Ca²⁺>K⁺,and a lower voltage was conducive to separate Li⁺from coexisting ions.The electrodes with carbon fiber cloth as current collector performed better in lithium recovery.The electrodes with carbon fiber cloth as current collector was applied to extract Li⁺from brine and concentrated seawater at0.6V.With brine as resource solution,the average extraction capacity of Li⁺was 22.2 mg/g,indicating that 22.5%of the Li⁺in the brine could be extracted.The values ofα_Li-Na,α_Li-Mg andα_Li-Cai-Ca were about 310,71 and 110,respectively.The current efficiency was over 89.0%and the specific energy consumption was 18.0 W h/mol.With concentrated seawater as resource solution,the mean extraction capacity of Li⁺was 21.1 mg/g,indicating that 14.0%of the Li⁺would be recovered.The values ofα_Li-Na,α_Li-Mg andα_Li-Ca were about 380,97and 110 times.The current efficiency was exceeded 86%,and Li⁺were extracted by consuming 18.6 W h per 1 mole of lithium recovered.The electrodes had good cycle performance and could be used to extract lithium repetitively.