Highly Selective and Pollution‐Free Electrochemical Extraction of Lithium by a Polyaniline/Li_xMn₂O₄ Cell

Abstract

Conventional lithium extraction processes are inefficient or inadaptable for application in salt‐lake brines with high Mg/Li ratios of ≥6. A new electrochemical cell, polyaniline (PANI)/LixMn2O4, was proposed to solve this problem for selective recovery of Li+ ions from brine water with high impurity cations (K+, Na+, Mg2+, etc). Benefiting from the unique selectivity of spinel LixMn2O4 for Li+ insertion and the high capacity of the PANI polymer for Cl− doping, this PANI/LixMn2O4 cell could simultaneously extract LiCl from a simulated brine with a high average current efficiency of 95 %, an energy consumption of 3.95 W h molLiCl−1, and a strong cycle ability with 70.8 % capacity retention over 200 cycles. In particular, this method avoids the use of additional chemicals, offering a highly efficient, pollution‐free technology for Li+ extraction from brine waters.

Electrochemical Methods for Lithium Recovery: A Comprehensive and Critical Review

“…Cao et al have recently reported the extraction of Li from simulated brine of Taijinair Lake (Qinghai, China), which has a very high Mg/Li ratio of 14.46 by the use of a plyaniline/Li x Mn 2 O 4 cell. [ 124 ] The authors employed a commercial LMO material that provided around 100 mAh g −1 for at least 100 cycles at slow current densities (0.1 mA cm −2 ). However, the specific charge dramatically decreased with the increment of the rate, reaching values of 65 mAh g −1 at 2.0 mA cm −2 .…”

“…Recently, Cao et al showed the use of nanowire of polyaniline (PANI) as counter electrode by the p‐doping/dedoping processes with reversible uptake/release of Cl − in the potential range of 0.2–0.7 V versus Ag/AgCl. [ 124 ] The material provided a reversible capacity of 77.6 mAh g −1 after 100 cycles in 1 m LiCl aqueous solution, corresponding to 78% capacity retention and coulombic efficiencies close to 100%. Owing to the abundant presence of different cations in the brine, a specific study of the electrochemical performance of PPy and PANI in such a solution would be of great interest.…”

LiFePO4 Battery Material for the Production of Lithium from Brines: Effect of Brine Composition and Benefits of Dilution

“…Since then, significant work has been dedicated to the investigation of the electrode materials to employ in the cell. The battery-like electrochemical cell consists of a lithiumselective battery electrode (e. g., LiFePO 4 , [17][18][19] λ-MnO 2 [20][21][22][23][24][25] ) combined with a chloride capturing (e. g., Ag, [17,18,[20][21][22]26,27] polyaniline, [23] polypyrrole [24] ) or a lithium-exclusion (e. g., nickel hexacyanoferrate, [25,28] ferrocyanide [19] ) counter-electrode. The selective extraction of lithium from brines is achieved because the lithium battery electrode undergoes a reduction reaction that induces the insertion of only lithium ions in the electrode, whereas the electrochemical reaction at the counter electrode does not involve lithium ions.…”

Increasing the Stability of LiMn2O4 Against Harsh Conditions During Lithium Recovery from Real Brine Solutions

“…They have the advantage of storing exclusively anions at the surface, which increases the selectivity of the extraction process. [ 39,40 ] The use of such reversible electrode reactions reduces the required amount of energy that is necessary for the extraction of lithium compared with irreversible counter reactions like water splitting. [ 33,41 ] Previously, an electrochemical ion‐pumping approach utilizing Ag and NiHCF CEs in combination with LMO have been presented with a very low energy consumption and an extremely high selectivity.…”

“…[ 48 ] It is important to investigate lithium recovery under real conditions. [ 37,40,44,49 ] Hence, the intercalation was investigated in two different real brine compositions (Zynh field, oil production water and Shoiba plant, desalination brine) and critical degradation mechanisms and side reactions are investigated. Redox electrodes such as platinum or titanium, which act as electron donors and acceptors, were suitable as CEs.…”