DOI: 10.5061/dryad.k6djh9wg2
title: Lithium extraction from brine through a decoupled and membrane-free electrochemical cell design

description: Efficient lithium extraction from natural seawater would greatly enhance
 the sustainability of renewable energy technologies such as batteries.
 Herein, we present a decoupled and membrane-free electrochemical cell
 design that cycles lithium ions between iron phosphate electrodes. The
 cathode in the brine is physically isolated from the anode in freshwater,
 but they are electrochemically interconnected through a pair of
 silver/silver halide redox electrodes. This design was compatible with
 harsh brines featuring Mg/Li molar ratios of up to 3258 and low lithium
 concentrations down to 0.15 mM to produce battery-grade lithium carbonate
 with purity &gt; 99.95%. Furthermore, the process could efficiently
 harness the osmotic energy of the brines, leading to up to ca. 21.5% of
 total energy savings. A pilot-scale cell with an electrode surface of
 33.75 m2 realized lithium extraction from Dead Sea brine at a recovery
 rate of 84.0%.
description: # Lithium extraction from brine through a decoupled and membrane-free
 electrochemical cell design
 [https://doi.org/10.5061/dryad.k6djh9wg2](https://doi.org/10.5061/dryad.k6djh9wg2) ## Data Description and File Structure The dataset includes concentration data and X-ray diffraction (XRD) patterns collected at KAUST Corelab. Electrochemistry-related measurements, such as osmotic energy and electrode potential, were conducted using a Keithley 2450 workstation at the KAUST IMR lab. The cycling performance of electrodes was evaluated using a Neware electrochemical testing system, also at the KAUST IMR lab. Pilot-scale testing was facilitated by Guangzhou Chienytech Co., Ltd., which provided the equipment and testing grounds. For more experimental details, refer to the Supplementary Materials PDF available on the Science website. In some data files, columns may represent different samples with varying test conditions or value ranges, which can result in inconsistent data lengths and empty cells at the end of columns. For instance, in the file "Extended_Data_Figure_1B.xlsx," the data length of Columns A and B is shorter than that of Columns C and D, resulting in empty cells in the range of A30 - B40. **Extended_Data_Figure_1B.xlsx**: This file contains data for Figure 1B in the main text, which shows the theoretical relationship between *concentration* (Cl⁻ or Br⁻ concentrations, millimole, mM) and *electrode potential* (potentials of Ag/AgCl or Ag/AgBr electrodes, millivolt, mV), calculated using the Nernst Equation. **Extended_Data_Figure_1D.xlsx**: This file contains data for Figure 1D in the main text, which shows: 1) the theoretical *potentials* (mV) of Ag/AgCl or Ag/AgBr electrodes in solutions with different *concentrations* of Cl⁻ or Br⁻ (mM), calculated using the Nernst Equation; and 2) the actual *potentials* (mV) of Ag/AgCl or Ag/AgBr electrodes tested in different *concentrations* (mM)  of Cl⁻ or Br⁻. The real *potentials* (mV) of the electrodes were measured using the Keithley 2450 EC, Tektronix Co. Ltd. **Extended_Data_Figure_1E.xlsx**: This file contains data for Figure 1E in the main text, which shows the *osmotic energy density* (watts per square meter, W m-2) obtained from different samples. These measurements were conducted using the homemade device shown in Figure S1, following the method described in the section "Measurement of Harvested Osmotic Energy" in the Supplementary Materials. The data were recorded using the Keithley 2450 EC, Tektronix Co. Ltd. **Extended_Data_Figure_2A.xlsx**: This file contains data for Figure 2A in the main text, which shows the *extraction rate* (micromoles per square centimeter per hour, μmol cm-2 h-1) of Li, Na, K, Mg, and Ca ions from different samples using our proposed membrane-free electrochemical cell. More details are recorded in the section "Lithium Extraction Processes" in the Supplementary Materials. **Extended_Data_Figure_2B.xlsx**: This file contains data for Figure 2B in the main text, which shows the *selectivity* (dimensionless number) of Li/Na, Li/K, Li/Mg, and Li/Ca from different samples using our proposed membrane-free electrochemical cell. The *selectivity* indicates the separation performance of our proposed membrane-free electrochemical cell. A high selectivity of Li/Mn means a high preference for lithium ions over "Mn"  ions. More details are recorded in the section "Lithium Extraction Processes" in the Supplementary Materials. **Extended_Data_Figure_2E.xlsx**: This file contains data for Figure 2E in the main text. We conducted 20 cycles of lithium extraction using our proposed membrane-free electrochemical cell, and the *concentrations* (mM) of ions were tested. The *Li concentration in feed brine* (mM) after different *cycles* is listed in Sheet 1, and the *ionic concentrations in the extraction solution* (mM; Li, Na, K, Mg, Ca) after different *cycles* are listed in Sheet 2. All data were tested by ICP-OES. **Extended_Data_Figure_2F.xlsx**: This file contains data for Figure 2F in the main text. The content of this file is similar to that of "Extended_Data_Figure_2E.xlsx", but it shows the *ion concentrations* (mM) of Ag and Fe after different cycles. All data were tested by ICP-OES. **Extended_Data_Figure_2G.xlsx**: This file contains data for Figure 2G in the main text. We conducted a 1000-cycle experiment using our proposed membrane-free electrochemical cell to investigate its robustness and duration. The constant-current charge curve of *voltage* (volt, V) vs. *time* (hour, h) was recorded using an electrochemical workstation. **Extended_Data_Figure_2H.xlsx**: This file contains data for Figure 2H in the main text. We conducted a 1000-cycle experiment using our proposed membrane-free electrochemical cell to investigate its robustness and duration. Our process consists of two subcycles: the adsorption subcycle, which extracts lithium from the brine, and the desorption subcycle, which releases lithium into the extraction solution. The *capacity retention* (dimensionless number) indicates the ratio of lithium-ion absorbed in each cycle over that of the first cycle, and the *coulombic efficiency* (dimensionless number) indicates the ratio of absorption and desorotion amounts in a pair of subcycles. **Extended_Data_Figure_3C.xlsx**: This file contains data for Figure 3C in the main text. These data show the amount of salts used for preparing 1.0 tons of mimic brine. The *content* (kg) indicates the salts weighed in the preparation process, and the *percentage* (dimensionless number) indicates the weight ratio of a certain salt to the total salts. **Extended_Data_Figure_3D.xlsx**: This file contains data for Figure 3D in the main text, which shows data for 112 cycles of lithium extraction using the pilot-scale device. The content of this file is similar to that of "Extended_Data_Figure_2E.xlsx". **Extended_Data_Figure_3E.xlsx**: This file contains data for Figure 3E in the main text. This file includes the *applied voltage* (V) by the external power source and the tested *voltage* (V) between the FePO4/LiFePO4 electrode pair in different cycles. These voltages were tested using the Keithley 2450 EC, Tektronix Co. Ltd., and recorded as time-weighted average values for each cycle. The *coulomb quantity* (coulomb, C) was calculated by integrating the current-time curve for each cycle. **Extended_Data_Figure_3F.xlsx**: This file contains data for Figure 3F in the main text. This file includes the XRD pattern of our product and the standard PDF card of lithium carbonate. **Supplementary_Figure_S3A.xlsx** - **Supplementary_Figure_S3F.xlsx**: These files contain data for Figures S3A - S3F in the Supplementary Materials, respectively. These data reveal the *potentials* (mV) of different ions inserted into the FePO4 electrode, tested using the linear sweep voltammetry method with an electrochemical station. Linear sweep voltammetry measures the *current* (ampere, A) at a working electrode while the voltage (mV) between the working electrode and a reference electrode is swept linearly over time. **Supplementary_Figure_S4.xlsx**: This file contains data for Figure S4 in the Supplementary Materials, which shows the constant-voltage charge curve of lithium extraction (*current* vs. *time*) from different brines. The content of this file is similar to that of "Extended_Data_Figure_2G.xlsx". **Supplementary_Figure_S6.xlsx**: This file contains data for Figure S6 in the Supplementary Materials, which shows the *potentials* (mV) of each electrode in the lithium extraction process. The content of this file is similar to that of "Extended_Data_Figure_3E.xlsx". **Supplementary_Figure_S10A.xlsx**: This file contains data for Figure S10A in the Supplementary Materials. The content of this file is similar to that of "Extended_Data_Figure_2E.xlsx". **Supplementary_Figure_S10B.xlsx**: This file contains data for Figure S10B in the Supplementary Materials. The content of this file is similar to that of "Supplementary_Figure_S4.xlsx". **Supplementary_Figure_S11.xlsx** and **Supplementary_Figure_S12.xlsx**: These files contain data for Figures S11 and S12 in the Supplementary Materials, respectively. They show the constant-voltage charge curves in the preparation processes of LiFePO4 electrodes and Ag/AgCl electrodes. The content of this file is similar to that of "Supplementary_Figure_S4.xlsx". ### Software for the data Data files are stored in Excel format compatible with Microsoft Office versions later than 2003. Each file is named according to the figure in which the plotted data appears, with additional details on sample descriptions and data interpretation provided within the files. Supplementary movies are compressed using H.264 video coding for compatibility across various players. Generally, the movies can be read by the default video players and opened by direct double click. If compatibility issues arise, it is recommended to use the Microsoft Edge browser: 1. Download the movie file; 2. Open a new tab in Microsoft Edge; and 3. Drag the downloaded file into the browser tab.