Optimized Lithium Recovery from Brines by using an Electrochemical Ion‐Pumping Process Based on λ‐MnO₂ and Nickel Hexacyanoferrate

Abstract

Currently, Li is mainly produced from Li‐rich brines through the lime–soda evaporation process, which requires a long time and several purification steps, and has a severe environmental impact. Herein, ion‐pumping technology based on λ‐MnO2 as lithium‐capturing electrode is presented. The method has high lithium selectivity and can increase the lithium purity from 4.1 to 96 % in a single step. In addition, the time required to achieve the target lithium concentration (5000 ppm) can be reduced from the 12–14 months needed for the lime–soda evaporation process to less than 7.4 h. The small volume of water required, the absence of any chemical reactant, the recyclability of the used electrodes, and the possibility to combine ion‐pumping technology with renewable energy sources makes this process a potential ecofriendly alternative to the current lithium‐recovery methods.

Electrochemical Lithium Recovery with a LiMn2O4–Zinc Battery System using Zinc as a Negative Electrode

“…This result is attributed to the preference of lithium insertion into the λ‐MnO 2 spinel structure; insertion of lithium is structurally and energetically favorable compared with other ions . The lithium selectivity in the LMO‐Zn system appears to be low in comparison with the previous study, and a good explanation for this difference other than the difference of the solution concentration between the two studies is not available at present. The crossover of zinc ions through the anion‐exchange membrane was 3 % (refer to Table S3 in the Supporting Information for details).…”

“…The systems with NiHCF appear to be energy‐efficient battery‐like systems, although the energy consumption varies depending upon the choice of cathode materials such as LFP or LMO. However, it was noted that the cation concentration such as Na + , K + in the recovery solution needs to be properly adjusted all the time so that NiHCF does not react with Li + ,…”

Undesired Bulk Oxidation of LiMn2O4 Increases Overpotential of Electrocatalytic Water Oxidation in Lithium Hydroxide Electrolytes

“…We propose that the process associated with Mn oxidation is delithiation of the bulk. This proposal is supported by the use of Li 1‐x Mn 2 O 4 as a battery material in similar aqueous electrolytes . The manganese valence can be converted to the lithiation value x using the stoichiometries of the formula Li 1‐x Mn 2 O 4 , i. e., x is twice the absolute valence change.…”

Cover Feature: Mechanistic Parameters of Electrocatalytic Water Oxidation on LiMn2O4 in Comparison to Natural Photosynthesis (ChemSusChem 22/2017)

“…It is conceivable that delithiation competes with deprotonation as the onset voltage of LiMn 2 O 4 delithiation is near 1.5 Vversus RHE in brine. [76] This analysisillustrated the diagnostic value of the Nernsts lope at the disk to identify and exclude side reactions.…”