Conventional lithium mining carries high environmental costs, and requires extensive extraction operations and water in a dry land. Much of the lithium produced today is extracted from brine reservoirs; the salt-rich waters must first be pumped into a series of large evaporation ponds where solar evaporation occurs over a number of months. Another lithium mining pathway is extraction of lithium from spodumene, lepidolite, petalite, amblygonite, and eucryptite requires a wide range of processes. Because of the amount of energy consumption and materials required, lithium production from mining is a much more costly process than brine extraction, even though these minerals have a higher lithium content than the saltwater.
Disclosed herein is a method comprising:
contacting a Li-containing aqueous liquid with a Li ion-selective membrane while simultaneously applying an electric field thereby extracting Li ions from the Li-containing aqueous liquid; and
intercalating the extracted Li ions into a cathode material.
Also disclosed herein is a method comprising:
introducing a Li-containing aqueous liquid into a first chamber of a device, wherein the device comprises an anode, a cathode comprising electrolytic manganese dioxide, a Li ion-selective membrane between the anode and the cathode, the first chamber contacting the anode a first surface of the Li ion-selective membrane; and a second chamber contacting the cathode and a second surface of the Li ion-selective membrane, wherein the second chamber contains a nonaqueous liquid electrolyte;
applying an electric field to the device;
permitting Li ions to selectively flow through the Li ion-selective membrane and into the second chamber; and
intercalating the extracted Li ions into the electrolytic manganese dioxide.
Further disclosed herein is a device comprising:
an anode;
a cathode comprising electrolytic manganese dioxide;
a Li ion-selective membrane between the anode and the cathode;
a first chamber contacting the anode a first surface of the Li ion-selective membrane; and
a second chamber contacting the cathode and a second surface of the Li ion-selective membrane.
The foregoing will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
Disclosed herein are methods and devices for high-efficient Li recovery from unconventional Li resources, (e.g. high salt waters/seawater) for direct low-cost Li battery materials manufacturing, bypassing the need for costly post-recovery processing using current methods.
In one configuration, coupled loops perform electrochemical Li extraction from salt waters and insert Li into the low-cost, transition-metal-oxide Li host structure materials. The harvested Li-contained host materials can then be used directly for high-energy Li battery cathode production, providing a low-cost Li source without the need for multiple processing steps. The proposed technology is generic and applicable to different high-salt waters such as seawater, brines and Li-recycle solutions, and industry wastes.
The Li extraction device disclosed herein includes an anode, a cathode comprising a manganese-containing material (e.g., electrolytic manganese dioxide (EMD)), a Li ion-selective membrane between the anode and the cathode, a first chamber contacting the anode a first surface of the Li ion-selective membrane, and a second chamber contacting the cathode and a second surface of the Li ion-selective membrane.
The anode may be made from, for example, stainless steel, nickel, titanium, tungsten, carbon, or graphite. In certain embodiments, the anode is made from corrosion-resistant metal(s) or alloy(s).
The cathode may be EMD or other oxides in a form of MOx, or fluorides in a form of MFy, or sulfides in a form of MS, where M=Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Si, Ge, Sn, Pb, P, As, Sb; 0≤x≤4; 0≤y≤6; 0≤z≤4.
The electrolytic manganese dioxide (EMD) constituting the cathode may be in the form of a film, powder, slurry or dispersion. The EMD may reside on a support structure, or be a free-standing film, or a dispersion in liquid. In certain embodiments, the EMD may be provided in a cartridge, where EMD is mixed with conductive carbon materials and dispersants. This EMD cartridge is flowable and electronic conductive.
An organic electrolyte is also provided on the cathode side of the device. The organic electrolyte may be a nonaqueous liquid electrolyte that is contained in the second chamber and that is in contact with the electrolytic manganese dioxide substrate. In certain embodiments, the nonaqueous liquid electrolyte includes at least one active salt and at least one solvent. Illustrative active salts include lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium bis(oxalato)borate (LiBOB), LiPF6, LiAsF6, LiBF4, LiCF3SO3, LiClO4, lithium difluoro oxalato borate (LiDFOB), LiI, LiBr, LiCl, LiSCN, LiNO3, LiNO2, and Li2SO4. Illustrative solvents include a carbonate (for example, propylene carbonate, diethyl carbonate, ethylene carbonate, dimethyl carbonate, or ethyl methyl carbonate, fluorinated carbonate), ether-based solvents (for example, dimethoxyethane, diglyme, dioxolane, tetrahydrofuran, dimethyl sulfoxide), or ester-based solvents like ethyl acetate. In certain embodiments, the active salt is present in the nonaqueous electrolyte in an amount of 0.1 mol/L to 20 mol/L, more particularly 0.5 mol/L to 5 mol/L.
A Li-containing aqueous liquid as a Li extraction source may be contained in the first chamber of the device. Illustrative Li-containing liquids include seawater, brine (e.g., a briny lake), an underground source of concentrated salt water, a Li-recycle solution, or an industry waste.
Illustrative Li ion-selective membranes include NASICON structure LiAB(PO4)3 (A=Al, Cr, Ga, Fe, Sc, In, Lu, Y, or La; B═Ge, Ti and Zr) e.g., Li1.5Al0.5Ge1.5(PO4)3 (LAGP), perovskite (ABO3)-type lithium lanthanum titanate (LLTO) Li3xLa1−3XTiO3 (0<x<0.16), LISICON structure Li2+2xZn1−xGeO4, Garnet structure Li5La3M2O12 (M=Ta, Nb) or substituted Garnets Li6ALa2M2O12 (A=Ca, Sr, Ba) and Li5Ln3Sb2O12 with different trivalent lanthanide cations (Ln=La, Pr, Nd, Sm, Eu).
A schematic of an example of a Li extraction device is shown in
The applied electric field is from −2V to 5V vs. SHE (Standard Hydrogen Electrode).
The device has several design considerations. First, Li interaction voltage and capacity should fit the device design. As shown in
Li extraction was demonstrated by applying a constant current density of 10 mA/gEMD (0.05 C). Due to limited volume of the anode chamber, Li solution with a relatively high concentration (5M LiCl/H2O) was used to maximize utilization rate of the EMD.
The selective Li extraction from the aqueous Li stream and its successful intercalation into EMD are contributed by the nonaqueous electrolyte and LAGP membrane, which play a key role in by removing the interferences of H+ and other cations. Competition intercalations between Li+ and H+ were identified if an aqueous electrolyte (cathode chamber) is used. At the first glance, the Li extraction voltage-capacity curve in 3-electrode system was very similar to the behaviors in nonaqueous electrolyte (
The Li and Mn of the harvested Li-EMD are precursor materials of many Li cathodes and thus can be used for direct cathode production. Depending on the target cathode formulas, the Li-EMD can be used as the sole precursor or mixed with additional transition metal or Li resources. For instance, Li0.5MnO2 can be processed through the extraction device by controlling Li intercalation content and then is used to prepared spinel LiMn2O4 by high-temperature calcination (
The methods and devices disclosed herein can provide high purity extracted Li. Owing to the high selectivity of the Li ion-selective membrane (e.g., Li1.5Al0.5Ge1.5(PO4)3(LAGP) membrane), only Li ions are allowed to intercalate into the electrolytic manganese dioxide (EMD), and other impurity metal cations or H+ are fully blocked within the feed stream; thus, the resulted Li-EMD has a high chemical purity. For example, the co-intercalated metal cations like Na+, K+, Mg2+, Ca2+ etc are below 0.1 mol per molar EMD, or lower than 0.01 mol per molar EMD. The harvested Li and EMD host (Li-EMD) both are precursor materials of battery and can be directly used for cathode mass production after adding necessary elements, depending on the design of target cathode formulas (e.g. LiMnxNiyCozO2, x+y+z=1). Since the absorbent regeneration and Li separation/purification, which have significant impacts on processing efficiency, energy consumption, and cost, are fully eliminated, this makes Li cathode production more cost competitive even compared with commercial ones. The Li extraction process can be realized by swapping the EMD cartridge at desired lithiation depth or after its full lithiation, thus simplifying automation in industry. Moreover, the environment impacts caused by chemical use and waste treatment associated with conventional precipitation processes are also avoided in the methods disclosed herein.
Material Preparation
Li-EMD to Spinel LiMn2O4: Electrolytic manganese dioxide (EMD) is received from TRONOX. The lithiated EMD, named as Li-EMD, was obtained by electrochemical Li extraction technology. To synthesize spinel LiMn2O4, the lithium content (x) in LixMnO2 was controlled less than 0.5 by adjusting the cutoff voltage during the 1st discharge process. After the electrode was washed and dried out, the electrode material was scraped off with a blade and calcined in air at 500° C. for 4 h. Then the calcined powder was mixed with Li2CO3 to make sure the ratio between Li and Mn is 0.5. The mixture was grounded and pressed into pellet, and calcined at 900° C. for 12 h under oxygen atmosphere, the corresponding heating and cooling temperature were set as 5° C./min and 2° C./min Finally, a dark powder is obtained, which is spinel LiMn2O4.
Li-EMD to LiNi1/3Co1/3Mn1/3O2: Ni(NO3)2.6H2O, Co(NO3)2.6H2O and LiOH.H2O were purchased from Sigma. The lithiated EMD powder was scraped off and mixed with Ni(NO3)2.6H2O and Co(NO3)2.6H2O in molar ratio of 1:1:1. Meanwhile, according to the lithium content in Li-EMD, a certain amount of LiOH.H2O was added into the above solid mixture with the ratio of 1.04:1 [(LiLi-EMD+LLiOH):(Ni+Co+Mn)]. The 4 mol % excess lithium is used to compensate the Li loss during calcinating. The final mixture was grounded and pre-calcinated at 500° C. for 4 h, and then grounded in mortar, followed by heating at 900° C. for 6 h in air. The ramping rate was controlled at 5° C./min for both heating and cooling. The final dark powder is LiNi1/3Co1/3Mn1/3O2, labelled as NMC333.
Li1.5Al0.5Ge1.5(PO4)3 synthesizing and characterization: Li1.5Al0.5Ge1.5(PO4)3 (LAGP) material was obtained from Ampcera. The powder had a mean particle size of approximately 500 nm.
Disks were uniaxially pressed in a 31.7 mm die with 5000 lbs applied force (4087 psi or about 28 MPa) for 30 seconds. The resulting pellets were placed in an MgO tray and covered with sacrificial powder of the same composition. The tray was closed with an MgO lid. The samples were fired in air with a heating rate of 1° C./minute to 850° C., held for 4 hours, and cooled to room temperature at 5° C./minute. The prepared LAGP (25 cm in length) presents a very dense structure and uniform element distribution. Before testing, the interfacial stability between LAGP and applied electrolytes (SE/LE-interface), including organic and aqueous electrolytes, was measured by in-situ impedance. To exclude interference, one side of LAGP was coated with Au and connected with SS-rod, the other uncoated fresh side contacted with liquid electrolytes for stability evaluation. There are two semicircles. (
The morphology of the materials was studied by scanning electron microscopy (SEM, JSM-IT2000). The crystal structure of our synthesized materials before and after Li extraction were analyzed by X-ray diffraction (XRD, Rikagu MiniFlex 600) in a 2-theta range of 10°-80° using Cu Kα radiation operated at 40 kV and 15 mA. Li content in the materials was analyzed by ICP-OES spectrometers (Optima 7300 DV). TEM samples were prepared by dispensing the cathode particles onto TEM lacey carbon grids inside an Ar-filled glovebox. TEM imaging was conducted on a Titan 80-300™ scanning/transmission electron microscope operated at 300 kV. STEM EELS microanalysis data were collected on an aberration corrected JEOL GrandARM-300F with the operation voltage of 300 kV, and a post-column Gatan Image Filter (GIF) working at 0.25 eV/channel energy dispersion.
Three cell configurations were employed for the materials validation and technology demonstration, including traditional coin-cell, liquid/LAGP/liquid-electrolyte cell and 3-electrode cell.
Coin-cell configuration with sandwiched anode/separator/cathode structure was used for fast material evaluation, where organic based Li solution of 1M LiPF6 in ethyl carbonate (EC) and ethyl methyl carbonate (EMC) (3:7 by weight), Li metal and active material (EMD, LiMn2O4 or NMC333) were used as electrolyte, anode, and cathode, respectively. EMD electrode was prepared by mixing electrode materials, PVDF and conductive carbon with a ratio of 80:10:10, and the mixing ratio in LiMn2O4 and NMC333 electrodes is 70:20:10.
The cell with LAGP is composed of multilayer structures, namely anode/aqueous-electrolyte/LAGP/organic-electrolyte/cathode, the corresponding aqueous electrolyte and organic electrolyte are Li-containing (5M LiCl) aqueous and 3M LiTFSI in EC/EMC (w/w=3:7). Stainless steel rod and EMD electrode were applied as anode and cathode, the corresponding EMD electrode loading is around 4 mg cm−2.
In 3-electrode cell, we developed a solvent assisted solid processing method to prepare free-standing EMD electrode and control the electrode architecture without sacrificing electrode stability/durability. The free-standing EMD electrode was attached onto Ti mesh current collector), forming the Li extraction film electrode, and the corresponding counter electrode is Pt. The used reference electrodes are Ag/AgCl electrode (in aqueous) or Ag/Ag+ electrode (in organic electrolyte). The testing voltage in three-electrode cell was set between open circuit voltage (OCV) and −0.54 V, and the corresponding current density is 0.1 C (1 C=200 mA/g).
In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention.
This application claims the benefit of U.S. Provisional Appl. No. 63/214,094, filed Jun. 23, 2021, which is incorporated herein by reference.
This invention was made with Government support under Contract DE-AC0576RL01830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.
Number | Date | Country | |
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63214094 | Jun 2021 | US |