Abstract
The objective of this work was to evaluate obtaining LiOH directly from brines with high LiCl concentrations using bipolar membrane electrodialysis by the analysis of Li+ ion transport phenomena. For this purpose, Neosepta BP and Fumasep FBM bipolar membranes were characterized by linear sweep voltammetry, and the Li+ transport number in cation-exchange membranes was determined. In addition, a laboratory-scale reactor was designed, constructed, and tested to develop experimental LiOH production tests. The selected LiCl concentration range, based on productive process concentrations for Salar de Atacama (Chile), was between 14 and 34 wt%. Concentration and current density effects on LiOH production, current efficiency, and specific electricity consumption were evaluated. The highest current efficiency obtained was 0.77 at initial concentrations of LiOH 0.5 wt% and LiCl 14 wt%. On the other hand, a concentrated LiOH solution (between 3.34 wt% and 4.35 wt%, with a solution purity between 96.0% and 95.4%, respectively) was obtained. The results of this work show the feasibility of LiOH production from concentrated brines by means of bipolar membrane electrodialysis, bringing the implementation of this technology closer to LiOH production on a larger scale. Moreover, being an electrochemical process, this could be driven by Solar PV, taking advantage of the high solar radiation conditions in the Atacama Desert in Chile.
Highlights
In recent years, lithium has become a mineral of great interest worldwide
The presence of other elements such as K, Mg, and Ca present in Salar de Atacama brine was not considered, as this study focuses on transport phenomena associated with lithium and the effect of high concentrations
The CMX and CMB cation-exchange membranes’ water uptake and thickness were measured after equilibrium with LiCl and LiOH solutions, which they were in contact with during the Bipolar membrane electrodialysis (BMED) LiOH production process
Summary
Its demand has increased due to its use in lithium-ion batteries for electric vehicles and consumer electronics, which has been boosted in some countries by energy policies that promote clean energy usage. Lithium hydroxide (LiOH) shows high projections in the production of battery cathodes [1,2]. By 2030, lithium consumption in electric vehicle batteries is expected to account for 80% of aggregate lithium consumption. Lithium hydroxide is projected to account for 57% of lithium compound demand, compared to 24% in 2019 [3]. Some key advantages of cathodes produced from lithium hydroxide over other chemical compounds are better power density, longer life cycle, and improved safety characteristics [4,5,6,7]
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