Cross-Reference

[0001] This application claims the benefit of U.S. Provisional Application No.

63/407,861, filed September 19, 2022, which application is incorporated herein by reference in its entirety.

Background

[0002] Certain clathrates, such as crown ethers, can form molecular “cages” that can envelop and bind to lithium ions. Crown ethers can be used to concentrate lithium ions by liquidliquid extraction. Lithium containing brines are one type of natural resource for extracting useful lithium. Methods are needed for the purification of lithium from dilute sources, the production of smooth, high-purity lithium metal and lithium metal alloys, and the preparation of lithium and lithium alloy anodes for lithium metal batteries.

Summary

[0003] The present disclosure provides electrolytic systems and methods for lithium extraction from lithium salt containing brines.

[0004] Lithium has good natural abundance, but is diffusely distributed. Brine and seawater can have significant amounts of lithium salts that could be harvested to provide lithium metal. However, in order to do so, salts are often concentrated before being reduced to lithium metal.

[0005] Clathrates can be coordination compounds that form molecular “cages” that can envelop and bind a target chemical entity, often with a high degree of specificity. Crown ethers can comprise cyclic compounds containing several ether groups. Crown ethers have been developed as specific clathrates for alkali and alkaline earth compounds. Cryptands are polycyclic compounds that provide an additional class of alkali and alkaline earth cation selective clathrates, and include nitrogen containing cryptands and ortho ester cryptands. See Steed, J. W. First- and Second-Sphere Coordination Chemistry of Alkali Metal Crown Ether Complexes. Coordination Chemistry Reviews 2001, 215 (1), 171-221; see also Low, H. et al., Self-assembled orthoester cryptands: orthoester scope, postfunctionalization, kinetic locking and tunable degradation kinetics. Chem. Sei. 2018, 9, 4785-4793, each of which are incorporated herein by reference in their entirety. A particularly high degree of lithium selectivity can be achieved with crown ethers, such as illustrated in , US9850226, which is incorporated herein by reference in its entirety. Crown ethers can be used to concentrate lithium ion by liquid-liquid extraction, and by membrane separation methods, including electrodialysis. See He, L., et al., CN1 13293300; Wang, J., et al., CN110564965, each of which are incorporated herein by reference in their entirety.

[0006] In the context of lithium batteries, crown ethers and other alkali cation complexing agents have been studied as a means to inhibit the formation of dendrites during repeated battery cycling. See e.g., Zhao, J., et al., Introducing Crown Ether as a Functional Additive for High-Performance Dendrite-free Li Metal Batteries. ACS Appl, Energy Mater, 2021, 4 (8), 7829-7838, which is incorporated herein by reference in its entirety.

[0007] Improved methods are needed for the purification of lithium from dilute sources, the production of smooth, high-purity lithium metal and lithium metal alloys, and the preparation of lithium and lithium alloy anodes for lithium metal batteries.

[0008] In accordance with some embodiments of the present disclosure, a system is disclosed for extracting lithium metal from a brine. The system can include an anode, disposed in the brine, and a solution of an organic solvent having as dissolved solutes a coordination compound, and a lithium salt, wherein the solution is in contact with the brine. In some embodiments, the organic solvent is insoluble in the brine. In some embodiments, the coordination compound and the lithium salt are also insoluble in the brine, and the coordination compound selectively coordinates lithium cation in preference to other cations. In some embodiments, water is insoluble in the organic solvent. As used herein, “insoluble” may refer to two substances that phase separate when in contact with each other. Small amounts of one substance forming one phase may solvate in the other phase. The organic solvent may be insoluble in the brine to the extent that organic solvent retains a substantial portion of its mass upon multiple instances of contact with the brine. Less than 5, 4, 3, 2, 1, 0.5, 0.1, 0.05, or 0.01% of the mass of the organic solvent may dissolve in the brine. The brine may be insoluble in the organic solvent to the extent that negligible amounts of water from the brine may solvate in the organic solvent. The negligible amount of water may be less than 1000, 100, 10, or 1 ppm, such that the presence of water in the organic solvent does not substantially affect the quality of lithium metal deposited using the system. Such embodiments can further include an electrically conductive substrate which is in contact with the water-immiscible phase but physically separated from the brine. The system can be configured so that when voltage is applied across the anode and the electrically conductive substrate, lithium cation is extracted from the brine and a layer of lithium metal or lithium metal alloy is deposited on the surface of the electrically conductive substrate. [0009] According to some embodiments, the coordination compound is a lithium ion selective clathrate. In some embodiments, the lithium ion selective clathrate is selected from the group consisting of a crown ether, a nitrogen-containing cryptand, and an orthoester cryptand. In some embodiments the clathrate is a crown ether. In some embodiments the crown ether is selected from the group consisting of 14-crown-4, substituted derivatives of 14-crown-4, 12- crown-4, substituted derivatives of 12-crown-4, 15-crown-5, substituted derivatives of 15-crown- 5, and combinations thereof. The lithium ion selective clathrate may selectively bind to a lithium ion over other cations present in the brine, e.g., magnesium, calcium, sodium, or potassium. The degree of selectivity may depend on the operating conditions, e.g., the temperature, the pressure, and the specific composition of the brine and the organic solvent.

[0010] According to some embodiments, the lithium salt comprises an anion with the chemical structure of (R S(O) ₂ ) ₂ N- where R is a substituent selected from the group of alkyl, perfluorinated alkyl, partially fluorinated alkyl, aryl, perfluorinated aryl, partially fluorinated aryl, and combinations thereof. In some embodiments, R can comprise a polymer. For example, R can be a polymer backbone comprising a plurality of anionic moieties that balance the positive charge of lithium ions. A lithium salt can comprise lithium bis(oxalato)borate, lithium 12-hydroxystearate, lithium acetate, lithium amide, lithium aspartate, lithium azide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium borohydride, lithium bromide, lithium carbonate, lithium chlorate, lithium chloride, lithium citrate, lithium cyanide, lithium diphenylphosphide, lithium hexafluorogermanate, lithium hexafluorophosphate, lithium hypochlorite, lithium hypofhiorite, lithium metaborate, lithium methoxide, lithium naphthalene, lithium niobate, lithium nitrate, lithium nitrite, lithium oxalate, lithium perchlorate, lithium stearate, lithium succinate, lithium sulfate, lithium sulfide, lithium superoxide, lithium tantalate, lithium tetrachloroaluminate, lithium tetrafluoroborate, lithium tetrakis(pentafluorophenyl)borate, lithium triflate, lithium tungstate, or any combination thereof. In some embodiments, a lithium salt can comprise an organic anion selected from the group consisting of bis(trifluoromethanesulfonyl)imide (TFSI), N- butyl-N- methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PyruTFSI), and l-ethyl-3- methylimidazolium-bis(trifluoromethylsulfonyl)imide (EMI-TFSI), and any combination thereof. In some embodiments, a lithium salt can comprise Li2SO4, Li2CO3, LiPF6, LiBF4, LiClO4, LiTFSI, and combinations thereof. In some embodiments, a lithium salt can comprise LiPF6, LiBF4, LiSbF6, LiAsF6, LiSbF6, UCF3SO3, Li(CF3SO2)3C, Li(CF3SO2)2N, LiC4F9SO3, LiClO4, LiAlO4, L1A1C14, LiAlF4, LiBPh4, LiBioCllO, CH3SO3Li, C4F3SO3Li, (CF3SO2)2NLi, LiN(CxF2x+lSO2)(CxF2y+lSO2) (wherein x and y are natural numbers), CF3CO2L1, LiCl, LiBr, Lil, LIBOB (lithium bis(oxalato)borate), lower aliphatic carboxylic acid lithium, lithium terphenylborate, lithium imide, or any combination thereof. In some embodiments, a concentration of the lithium salt may be in a range of about 0.1 molar (“M”) to about 2.0 M. In some embodiments, a concentration of the lithium salt is at least 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, or 3 M. In some embodiments, a concentration of the lithium salt is at most 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3, 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0 M.

[0011] According to some embodiments, the organic solvent is selected from the group consisting of CH ₃ (CH ₂ ) _P O[(CH ₂ ) _q OCH ₂ (CF ₂ )„CH ₂ O](CH ₂ ) _r CH ₃ (n = 1-15, p = 0-15, q = 0-15, r = 0-15, x = 1-30), CH ₃ [(CH2) _P OCH ₂ (CF2) _n CH ₂ O(CH2) _? lrCH3 (n = 1-15, p = 0-15, q = 0-15, x = 1 -30, wherein the n, p, and x is independent from the values of n, p, and x chosen in the prior chemical structure), alkanes, and combinations thereof.

[0012] In some embodiments, the organic solvent comprises CH3(CH2) _J pO[(CH2) ₉ OCH2(CF2)j _I CH ₂ O] _x (CH2)rCH3, wherein n is at least 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH3(CH2)/>O[(CH ₂ ) _? 0CH2(CF ₂ ) _J iCH ₂ O] _A :(CH ₂ )rCH3, wherein n is at most 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH ₃ (CH ₂ )^O[(CH ₂ ) ₉ OCH ₂ (CF ₂ ) _fl CH ₂ Oh(CH ₂ )XlH ₃ , wherein^ is at least 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH ₃ (CH ₂ )pO[(CH ₂ ) _? 0CH ₂ (CF ₂ )«CH ₂ O] _x (CH ₂ )X3H ₃ , wherein p is at most 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH ₃ (CH ₂ )pO[(CH2) ₉ OCH ₂ (CF2) _fl CH ₂ O] _x (CH ₂ )X:H ₃ , wherein q is at least 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH ₃ (CH ₂ )^O[(CH ₂ ) ₉ 0CH ₂ (CF ₂ )XH ₂ O]x(CH ₂ )X3H ₃ , wherein q is at most 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH ₃ (CH ₂ ) _P O[(CH2) ₉ OCH ₂ (CF ₂ ) _fl CH ₂ O] ₁ (CH ₂ )A:H ₃ , wherein r is at least 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH3(CH ₂ )^O[(CH ₂ ) _? 0CH ₂ (CF ₂ )XH ₂ Oh(CH ₂ )X3H3, wherein r is at most 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH ₃ (CH ₂ ) _j pO[(CH2) _<? OCH ₂ (CF2) _ffl CH ₂ O] _x (CH ₂ ) _r CH3, wherein x is at least 1, 5, 10, 15, 20, 25, or 30. In some embodiments, the organic solvent comprises CH ₃ (CH ₂ ) _P O[(CH2) _? OCH ₂ (CF2)z _I CH ₂ OXCH2)rCH ₃ , wherein x is at most 1, 5, 10, 15, 20, 25, or 30.

[0013] In some embodiments, the organic solvent comprises CH ₃ [(CH ₂ ) _/ >OCH ₂ (CF2)nCH ₂ O(CH2) _? ]xCH3, wherein n is at least 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH ₃ [(CH ₂ ) _/; OCH2(CF ₂ )„CH2O(CH ₂ ) _? ].vCH ₃ , wherein n is at most 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH3[(CH2) _/ >OCH2(CF2) _n CH2O(CH2) _? ]xCH3, wherein p is at least 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH3[(CH2)pOCH2(CF2)nCH2O(CH2) ₅ ]i-CH3, wherein p is at most 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CHs[(CH2)/iOCH2(CF2)ziCH2O(CH2) _? }rCH3, wherein q is at least 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH3[(CH2)pOCH2(CF2)nCH2O(CH2) ₉ ]rCH3, wherein q is at most 1, 5, 10, or 15. In some embodiments, the organic solvent comprises CH ₃ [(CH2) _/ -OCH ₂ (CF2) _fl CH2O(CH2) _f ] _I CH3, wherein x is at least 1, 5, 10, 15, 20, 25, or 30. In some embodiments, the organic solvent comprises CH3[(CH2)pOCH2(CF2)nCH2O(CH2) ₉ ]xCH3, wherein r is at most 1, 5, 10, 15, 20, 25, or 30.

[0014] In some embodiments, the organic solvent comprises an ether functional group, a fluoroalkyl group, a fluoroether group, or any combination thereof. In some embodiments, an organic solvent can comprise dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, 1,3 -diox olan-2-one, 4-methyl-l,3-dioxolan-2-one, oxolan-2-one, dimethoxyethane, bis(2,2,2-trifluoroethyl) ether, poly(ethylene glycol), perfluorinated polyethylene glycol), partially fluorinated poly(ethylene glycol), 2, 2,3,3- Tetrafluoropropyl trifluoromethyl ether, or any combination thereof. In some embodiments, an organic solvent can comprise an organic carbonate compound, an ester compound, an ether compound, a ketone compound, an alcohol compound, an aprotic bipolar solvent, or a combination thereof. The carbonate compound can comprise an open chain carbonate compound, a cyclic carbonate compound, a fluorocarbonate derivative thereof, or a combination thereof. In some embodiments, the chain carbonate compound can comprise diethyl carbonate (“DEC”), dimethyl carbonate, (“DMC"), dipropyl carbonate (“DPC”), methylpropyl carbonate (“MPC”), ethylpropylcarbonate (“EPC”), methylethyl carbonate (“MEC”), or a combination thereof. In some embodiments, the cyclic carbonate compound can comprise ethylene carbonate (“EC”), propylenecarbonate (“PC”), butylene carbonate (“BC”), fluoroethylene carbonate (“FEC”), vinylethylene carbonate (“VEC"), or a combination thereof. In some embodiments, the fluorocarbonate compound can comprise fluoro ethylene carbonate (“FEC”), 4,5-difluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,4,5-trifluoroethylene carbonate, 4, 4,5,5- tetrafluoroethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4,4,5-trifluoro-5-methylethylene carbonate, trifluoromethylethylene carbonate, or a combination thereof. In some embodiments, the carbonate compound can comprise a combination of cyclic carbonate and chain carbonate, in consideration of the dielectric constant and the viscosity of the electrolyte. In some embodiments, the carbonate compound can comprise a mixture of such chain carbonate and/or cyclic carbonate compounds as described above with a fluorocarbonate compound. In some embodiments, the fluorocarbonate compound may increase solubility of a lithium salt to improve ionic conductivity of the electrolyte, and may facilitate formation of the thin film on the anode. In some embodiments, the ester compound comprises methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate (“MP”), ethyl propionate, y-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, methyl formate, or any combination thereof. In some embodiments, the ether compound comprises dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2- methyltetrahydrofuran, tetrahydrofuran, or any combination thereof. An example of the ketone compound is cyclohexanone. In some embodiments, the alcohol compound can comprise ethyl alcohol or isopropyl alcohol. In some embodiments, the aprotic solvent can comprise a nitrile (such as R — CN, wherein R is a C2-C20 linear, branched, or cyclic hydrocarbon-based moiety that may include a double-bond, an aromatic ring or an ether bond), amides (such as formamide and dimethylformamide), dioxolanes (such as 1,2-dioxolane and 1,3 -dioxolane), methylsulfoxide, sulfolanes (such as sulfolane and methylsulfolane), l,3-dimethyl-2- imidazolidinone, N-methyl-2-pyrrolidinone, nitromethane, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, triester phosphate, or any combination thereof. In some embodiments, an electrolyte can comprise an aromatic hydrocarbon organic solvent in a carbonate solvent. In some embodiments, an aromatic hydrocarbon organic solvent can comprise benzene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3- trifluorobenzene, 1 ,2,4-trifLuorobenzene, chlorobenzene, 1 ,2-dichlorobenzene, 1,3- dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, iodobenzene, 1,2-diiodobenzene, 1,3 -diiodobenzene, 1,4-diiodobenzene, 1,2,3 -triiodobenzene, 1,2,4-triiodobenzene, 2 -fluorotoluene, 3 -fluorotoluene, 4-fluorotoluene, 2,3 -difluorotoluene, 2,4- difluorotoluene, 2,5 -difluorotoluene, 2,6-difluorotoluene, 3,4-difluorotoluene, 3,5- difluorotoluene, 2,3,4-trifluorotoluene, 2,3,5-trifluorotoluene, 2,3,6-trifluorotoluene, 3,4,5- trifluorotoluene, 2,4,5-trifluorotoluene, 2,4,6-trifhiorotoluene, 2-chlorotoluene, 3-chlorotoluene, 4-chlorotoluene, 2,3 -di chlorotoluene, 2,4-dichlorotoluene, 2,5-dichlorotoluene, 2,6- dichlorotoluene, 2,3,4-trichlorotoluene, 2,3,5-trichlorotoluene, 2,3,6-tdchlorotoluene, 3,4,5- trichlorotoluene, 2,4,5-trichlorotoluene, 2,4,6-trichlorotoluene, 2-iodotoluene, 3 -iodotoluene, 4- iodotoluene, 2,3 -diiodotoluene, 2,4-diiodotoluene, 2,5-diiodotoluene, 2,6-diiodotoluene, 3,4- diiodotoluene, 3,5-diiodotoluene, 2,3,4-triiodotoluene, 2,3,5-triiodotoluene, 2,3,6-triiodotoluene, 3,4,5-triiodotoluene, 2,4,5-triiodotoluene, 2,4,6-triiodotoluene, o-xylene, m-xylene, p-xylene, and combinations thereof.

[0015] According to some embodiments, a method is disclosed of extracting lithium metal from a brine, the method including the steps of

(1) disposing an anode in the brine;

(2) placing a solution in contact with the brine, the solution comprising an organic solvent and having as dissolved solutes a coordination compound and a lithium salt, wherein the organic solvent is insoluble in the brine, and wherein the coordination compound selectively coordinates lithium cation in preference to other cations;

(3) disposing an electrically conductive substrate to be in contact with the solution, but physically separated from the brine; and

(4) applying voltage across the anode and the electrically conductive substrate, thereby causing a layer of lithium metal or lithium metal alloy to be deposited on a surface of the electrically conductive substrate.

[0016] According to some embodiments, the method further includes removing the layer of lithium metal or lithium metal alloy from contact with the brine and cleaning a surface of the layer of lithium metal or lithium metal alloy. According to some embodiments, the cleaning includes contacting with an organic solvent. According to some embodiments, the organic solvent is hexane, dimethyl carbonate or 1,2-dimethoxyethane. According to some embodiments, contacting with the organic solvent involves operations selected from the group consisting of soaking, rinsing, and combinations thereof. According to some embodiments, the cleaning includes brushing with a soft sponge and sonication in the organic solvent.

[0017] In accordance with embodiments of the present disclosure, a system is disclosed for extracting one or more metals from a brine, the system including an anode, disposed in the brine, and an organic solution of an organic solvent having as dissolved solutes one or more coordination compounds, and salts of one or more metals, wherein the organic solution is in contact with the brine. In this embodiment, the organic solvent, the one or more coordination compounds, and the coordination compounds are configured to coordinate cations of the one or more metals. Some embodiments further include an electrically conductive substrate, in contact with the solution, but physically separated from the brine. The system is configured so that when voltage is applied across the anode and the electrically conductive substrate, cations of the one or more metals are extracted from the brine and a layer of a metal or metal alloy is deposited on a surface of the electrically conductive substrate. [0018] According to some embodiments, the one or more coordination compounds are configured to selectively coordinate specific metal cations, thereby providing a means of controlling the composition of the layer of metal or metal alloy.

[0019] In accordance with some embodiments of the present disclosure, a method for extracting lithium from an aqueous lithium resource is disclosed, the method comprising: transporting lithium ions from the aqueous lithium resource to a non-aqueous electrolyte comprising one or more coordination compounds, wherein the one or more coordination compounds coordinate with the lithium ions; transporting the lithium ions coordinated by the one or more coordination compounds from the non-aqueous electrolyte to a substrate; and electrodepositing lithium metal on the substrate by reducing the lithium ions to the lithium metal. In some embodiments, the transporting and the electrodepositing are performed concurrently, In some embodiments, the transporting and the electrodepositing are performed by applying an electric potential to one or more electrochemical cells, wherein the one or more electrochemical cells comprise or are in contact with the aqueous lithium resource, the non-aqueous electrolyte and the substrate.

[0020] In some embodiments, the one or more coordination compounds are substantially insoluble in the aqueous lithium resource. In some embodiments, water in the aqueous lithium resource is insoluble in the non-aqueous electrolyte. In some embodiments, the non-aqueous electrolyte comprises an organic solvent. In some embodiments, the organic solvent comprises a molecule comprising one or more carbon-fluorine bonds.

[0021] hi some embodiments, the non-aqueous electrolyte comprises a lithium salt. In some embodiments, the lithium salt is substantially insoluble in the organic solvent in the absence of the one or more coordination compounds.

[0022] In some embodiments, the aqueous lithium resource comprises sodium, potassium, magnesium, calcium, boron, chlorine, SO4 ² ", nitrogen, an alkali metal, an alkali earth metal, or any combination thereof. In some embodiments, the one or more coordination compounds selectively coordinate with the lithium ions. In some embodiments, the one or more coordination compounds preferentially coordinate with the lithium ions over non-lithium cations. In some embodiments, the non-lithium cations comprise any one of sodium, potassium, magnesium, calcium, and any combination thereof.

[0023] In some embodiments, the one or more coordination compounds comprise a plurality of ether groups, wherein oxygen atoms of the plurality of ether groups coordinate with the lithium ions. In some embodiments, the one or more coordination compounds comprise one or more crown ethers. In some embodiments, the one or more coordination compounds comprise a plurality of amine groups, wherein nitrogen atoms of the plurality of amine groups coordinate with the lithium ions. In some embodiments, the one or more coordination compounds comprise one or more cryptands. In some embodiments, the one or more coordination compounds comprise any one of lariat ethers, multi-armed ethers, calixarenes, spherands, cryptaspherand, hemispherand, podand, and any combination thereof.

[0024] In some embodiments, the aqueous lithium resource comprises a geological resource, hi some embodiments, the aqueous lithium resource comprises brine, hi some embodiments, the aqueous lithium resource is pretreated by dilution, concentration, filtration, nanofiltration, absorption or extraction using organic molecules or inorganic sorbents, electrodialysis using a membrane, concentration and precipitation, solvent extraction, pH adjustment, or any combination thereof. In some embodiments, the pH adjustment comprises adding an acid, a base, a buffer, or any combination thereof, hi some embodiments, the pretreatment removes magnesium in the aqueous lithium resource. In some embodiments, a ratio of magnesium to lithium in the aqueous lithium resource is about 0-100 by mass or by mols.

[0025] In some embodiments, the substrate comprises copper. In some embodiments, the lithium metal comprises less than 0.1 wt% or at% of nitrogen, oxygen, or both. In some embodiments, the lithium metal comprises less than 0.1 wt% or at% of boron. In some embodiments, the lithium metal comprises less than 0.1 wt% or at% of magnesium, aluminum, or both. In some embodiments, the lithium metal comprises less than 0.1 wt% or at% of non- conductive impurities. In some embodiments, the lithium metal comprises less than 0.1 wt% lithium alloys. In some embodiments, the lithium metal comprises less than 1 non-lithium subsurface structure per mm ³ . In some embodiments, the lithium metal comprises less than 1 non-lithium crystalline subsurface structure per mm ³ . In some embodiments, the lithium metal comprises a thickness of less than 100 pm.

Brief Description of the Drawings

[0026] The foregoing features of embodiments will be more readily understood by reference to the following detailed description, taken with reference to the accompanying drawings, in which:

[0027] Fig. 1 illustrates how, by varying the size of the ring, crown ether structure can be tailored to coordinate specific alkali metal cations.

[0028] Fig. 2 discloses an embodiment of the present disclosure for extracting lithium from a brine and depositing it onto a conductive substrate. [0029] Fig. 3 discloses an embodiment of the present disclosure, illustrating how lithium transport into an organic layer is facilitated by formation of a lithium coordination complex, and how other ions are prevented from entering the organic layer.

[0030] Fig. 4 discloses how embodiments of the present disclosure can allow gas formed at the conductive substrate surface to be dispersed away from the surface.

[0031] Fig. 5 shows how gas evolution can damage a solid coating on a conductive substrate in an electrolytic cell.

[0032] Fig. 6 provides an embodiment for which an organic layer is lighter than the brine, and sits atop of the brine, the organic layer being held in place by impermeable barriers.

[0033] Fig. 7 provides an embodiment for which an organic phase is trapped in an organogel. The organogel surrounds a conductive substrate and is submerged in a brine.

[0034] Fig. 8 shows a computer system, in accordance with some embodiments.

Detailed Description

[0035] Definitions. As used in this description and the accompanying claims, the following terms shall have the meanings indicated, unless the context otherwise requires:

[0036] In the context of this application, a “conductive substrate” can refer to an electrically conductive material that can function as a cathode in an electrolytic cell.

[0037] A “gel” can refer to an elastic solid.

[0038] An “organogel” can refer to a gel with a liquid component comprising an organic solvent. The liquid component is held in place by a cross-linked polymer.

[0039] An “organic liquid phase” in the context of the current application can include an organic liquid layer and an organogel.

[0040] A “brine” can refer to an aqueous salt solution. In the context of this application, the terms “brine” and “aqueous phase” can be used interchangeably.

[0041] In the context of this application, to “chelate” can be used synonymously with “coordinate”, and can mean to bind a cation by means of a “coordination compound.”

[0042] Lithium metal electrodes for lithium metal batteries can comprise a thin layer (usually < 50 pm thick) of lithium metal on a conductive substrate. Some processes for manufacturing lithium metal electrodes from brine can take multiple steps, including purification of brine, electrolysis of molten LiCl, and extrusion of Li ingots into thin films on copper.

[0043] The methods described herein can drastically simplify the process of extracting lithium from brine, a type of aqueous lithium resource, by electrodepositing lithium metal onto a conductive substrate directly from brine. To achieve this, an organic liquid phase that is impermeable to water and that selectively conducts Li ⁺ compared to other ions in the brine can be interposed between the brine and the conductive substrate, preventing direct contact of the conductive substrate with the brine. When voltage is applied across an anode in the brine and a cathode comprising the conductive substrate, lithium ions can be transported from the brine, through the organic phase, and lithium metal can electroplate onto the conductive substrate. In some embodiments, the organic liquid phase is disposed as an organic layer above or below the brine, and the conductive substrate is positioned within the organic layer. In some embodiments the organic liquid phase is an organogel that traps an organic liquid, the conductive substrate is positioned within the organogel, and the organogel contacts the brine. The positioning of the conductive substrate in the organic phase can (a) protect the conductive substrate from water, thereby substantially reducing or preventing hydrogen gas evolution at the surface of the conductive substrate, and (b) prevent the reduction of other metals in the brine in preference to the reduction of Li ⁺ to Li metal. Such positioning can obviate the need for some costly pretreatments to separate metal ions from the brine and membrane methods to prevent contact of the substrate with water. Moreover, because all ion transport occurs in the liquid phase, such transport can be more rapid compared to methods that may involve ion-selective membrane transport.

[0044] In electrodeposition systems, such as the embodiment described above, water contamination in phases which are in contact with the electrodepositing lithium metal can degrade the lithium metal. Accordingly, it is advantageous to prevent or substantially reduce the presence of water that contacts the lithium metal.

[0045] In some embodiments, the present disclosure provides a composition for use in a system or a method for electrodepositing lithium from an aqueous lithium resource. The composition can comprise a water-immiscible electrolyte and a coordination compound. The water-immiscible electrolyte can be an electrochemically stable electrolyte composition in the range of voltages that would need to be applied to deposit lithium metal. The water- immiscible electrolyte can be sufficiently hydrophobic so as to reduce water contamination to effectively nil or to acceptably low levels in the electrodeposition system. The water-immiscible electrolyte can be configured to solvate the coordination compound and the complex which it forms with lithium ions.

[0046] In some embodiments, the composition comprises a fluorinated electrolyte, e.g., FDMB (2,2,3,3-tetrafluoro-l,4-dimethoxylbutane), which can exhibit very high hydrophobicity, The organic liquid phase, in contact with the aqueous lithium resource, may contain at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 ppm, and/or at most about 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm of water during operation, which may be determined using a technique such as 1H NMR, Karl Fischer Titration, or NIR spectroscopy.

[0047] In contrast, certain solvents may not be suitable as the electrolyte, e.g., dichloromethane, because they may not be electrochemically stable during the deposition of lithium. Dichloromethane can to decompose before lithium ion is reduced to form lithium metal. The decomposition products of dichloromethane may further cause side reactions that make deposition uncontrollable or impossible. Dichloromethane may also ignite, as it is a flammable and volatile liquid under ambient conditions, and it is toxic. At 20 degrees Celsius, water may solvate in dichloromethane to up to about 0.24 wt%.

[0048] The selective transport of lithium through the organic liquid phase can occur by virtue of one or more coordination compounds within the organic liquid phase that selectively coordinate lithium cations compared to other metal cations, thereby solubilizing the lithium cation in the organic liquid phase. Suitable coordination compounds include clathrates, which can trap the lithium cation in a cage structure. Such clathrates can include crown ethers, lariat ethers, multi-armed ethers, calixarenes cryptands, spherands, crytaspherands, hemispherands, and podands. In some embodiments, the cryptands are nitrogen containing cryptands or orthoester cryptands. The organic liquid phase can further include a lithium cation with an organic anion that is soluble in the organic liquid phase but insoluble in the brine. In some embodiments, the organic liquid phase can further include a lithium cation with an inorganic anion (e.g., Cl") that is soluble in the organic liquid phase but insoluble in the brine. During electrolysis, lithium ions can be released from the coordination compounds to electroplate onto the surface of the conductive substrate. In order to maintain charge neutrality, lithium ions can be pulled from the brine to bind to the free coordination compounds that have released their lithium ion cargo.

[0049] In some embodiments, the composition can comprise one or more coordination compounds. The one or more coordination compounds can be configured to permit the passage of lithium ions through the organic liquid phase to the electro depositing lithium metal, without also carrying water molecules through the organic liquid phase. Without being bound to a particular theory, the coordination complex of a lithium ion in the one or more coordination compounds and in the organic liquid phase may avoid accommodating one or more water molecules. Certain coordination compounds may be capable of coordinating a lithium ion, but they may also solvate water molecules from the aqueous lithium resource. Solvating water molecules can permit the water molecules to contact electrodepositing lithium metal and degrade the lithium metal quality, by turning lithium metal to LiOH or Li ⁺ with H2 gas evolution. In some embodiments, the one or more coordination compounds can he configured to completely displace water molecules in the hydration shell of a lithium ion (in the aqueous phase) when accepting the lithium ion into the organic phase. The one or more coordination compounds can comprise, e.g., a cryptand, as disclosed herein. The coordination complex of a lithium ion, in the presence of the one or more coordination compounds and/or water, and the dynamics of passage of a lithium ion in hydration shell into the coordination complex in the organic phase, can be investigated by various experimental and theoretical methods, and rational design. For example, as disclosed herein, the geometry of the coordination complex can be tailored based on the size and shape of the coordination compounds as well as their molecular flexibility.

Theoretical/simulation methods such as molecular dynamics simulations or Monte Carlo simulations can provide free energies of solvation for coordination complexes containing zero to a number of water molecules, which can provide the thermodynamic favorability of water incorporation into the coordination complex during operation. Molecular dynamics can be used to investigate the kinetics of lithium ion exchange between the interface between the aqueous phase and the organic phase, the desolvation of lithium ion in water to its solvation into the coordination complex of the one or more coordination compounds. Various operational parameters can be investigated as well. Experimental methods, such as 1H NMR, Karl Fischer Titration, or NIR spectroscopy, can reveal the level of contamination of water into the organic liquid phase when the system is operated to deposit lithium.

[0050] hi some embodiments, the selectivity of lithium ion transport is veiy high, leading to highly pure lithium being electroplated onto the surface of the conductive substrate. In some embodiments the selectivity of lithium transport is reduced, leading to the electroplating of a lithium alloy. By varying the nature and amount of the one or more coordination compounds within the organic liquid phase, the lithium selectivity can be varied, so that other metal ions from the brine are transported and electroplated onto the conductive substrate in a controlled manner, allowing control over the composition of the electroplated lithium alloy.

[0051] In some embodiments, a coordination compound can be a cryptand or a crown ether. Fig. 1 illustrates an embodiment where the coordination compound comprises a crown ether. Crown ethers can selectively chelate metal ions that fit the size of the “crown”. Moreover, fine-tuning of pendant groups on the crown ethers allows control of their solubility in organic solvents. In particular, crown ethers can be optimized to make otherwise organic-solventinsoluble inorganic salts soluble in organic solvents. The rigidity and steric hindrance around crown ethers can also be fine-tuned to achieve very high Li ⁺ selectivity (R.E.C. Torrejos et al. Chem. Eng. J. 2017, 326, 921). Such fine-tuned crown ethers show promise for the liquid-liquid extraction of Li ⁺ from brine. Some embodiments of the present disclosure combine liquid-liquid extraction with lithium ion selective crown ethers in tandem with electrolysis to electrodeposit Li metal from brine. Likewise, a cryptand or a different coordination compound can be modified or adapted to achieve high Li ⁺ selectivity.

[0052] In an embodiment, as shown in Fig. 2, an electrolytic cell 100 includes a cathode comprising a conductive substrate 102 disposed at the bottom of the electrolytic cell 100. Covering the conductive substrate 102 can be an organic liquid phase 104, comprising an organic solvent that, in this embodiment, is denser than water. The organic liquid phase 104 can be immiscible with water. In some embodiments, the organic liquid phase 104 can be unreactive with lithium metal. In other embodiments, the organic liquid phase can form a stable solid electrolyte interface with lithium metal. The organic liquid phase 104 can include a lithium salt, LiX, which is soluble in the organic liquid phase by virtue of the lithium cation Li ⁺ forming a complex Li(cr) ⁺ with a crown ether (cr) or another coordination compound that selectively binds the Li ⁺ . The anion X" of the lithium salt can be an organic anion or an inorganic anion that is soluble in the organic liquid phase but not in water. Likewise, the crown ether or another coordination compound can be soluble in the organic liquid phase but not in water.

[0053] According to some embodiments, the coordination compound (e.g., crown ether) and LiX can be present in the organic liquid phase in a 1 : 1 molar ratio, thereby forming a chelate, Li(cr)X, with the coordination compound. In some embodiments, X" is (RSCb^N", denoted as RSI" (bis(R-substituted sulfonyl)imide). In some such embodiments, R = -F, -CF ₃ or -(CF ₂ ) ₃ CF ₃ .

[0054] According to some embodiments, the organic solvent in the organic liquid phase is CH ₃ OCH ₂ (CF ₂ ) _n CH2OCH3, where n = 2-6. According to some embodiments, n = 2, and the organic liquid phase is FDMB (2,2,3,3-tetrafluoro-l,4-dimethoxylbutane). According to some embodiments, n = 4, and the organic liquid phase is FDMH (2,2,3,3,4,4,5,5-Octafluoro-l,6- dimethoxylhextane). In some embodiments, n is at least 2, 3, 4, 5, or 6, and/or at most 2, 3, 4, 5, or 6. [0055] According to some embodiments, the crown ether has the chemical structure: where R and R’ are pendant organic groups, modulating the solubility of the crown ether. According to some embodiments, R and R’ are separately chosen from the group consisting of - (Cl 12),; _t CI I ; and -(CF0/-CF;, where m = 0-10 and p = 0-10. hi some embodiments, m is at least 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and/or at most 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or 0. In some embodiments, p is at least 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and/or at most 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or O.

[0056] According to some embodiments, the lithium ion selective crown ether is selected from the group consisting of 14-crown-4, substituted derivatives of 14-crown-4, 12-crown-4, substituted derivatives of 12-crown-4, 15-crown-5, substituted derivatives of 15-crown-5, and combinations thereof.

[0057] Disposed above the organic liquid phase 104 can be a brine 106, the brine 106 being an aqueous salt solution comprising dissolved lithium cations, Li ⁺ (aq). hi some embodiments the brine 106 is seawater or is derived from seawater. Disposed within the brine 106 can be an anode 108, connected by an external circuit to the cathode, and allowing electrons to flow from the anode to the cathode upon application of voltage across the electrolytic cell.

[0058] According to some embodiments, the anode material includes graphite, platinum, platinized titanium, ruthenium, or iridium.

[0059] Because the anion X" of the lithium salt in the organic liquid phase 104 can have a high partition coefficient in the organic phase vs. the aqueous phase, it can remain confined to the organic liquid phase 104 and not migrate to the brine 106.

[0060] According to some embodiments, material making up the conductive substrate 102 is selected from the group consisting of copper, aluminum, graphite coated copper, nickel, stainless steel, platinum, gold, and metal alloys. In a preferred embodiment, the conductive substrate 102 includes copper.

[0061] As embodied in Fig. 2 and Fig. 3, as voltage is applied across the anode and the conductive substrate, a layer of lithium metal 110 deposits on the surface of the conductive substrate 102 according to the electrochemical reaction:

Li(cr) ⁺ (org) + e" = Li (s) + cr (org). where “org” can denote that the species is in the organic phase, “aq" can denote that the species is in the aqueous phase (i.e. the brine), and “s” can denote a solid state species.

[0062] The empty crown ether can then diffuse to the interface between the aqueous and organic phases to coordinate Li ⁺ from the aqueous phase, thereby allowing lithium to enter the organic liquid phase as a crown ether complex:

Li ⁺ (aq) + cr = Li(cr) ⁺ (org).

[0063] In some embodiments, Na ⁺ and other larger ions cannot enter the organic liquid phase because the ring of the crown ether is relatively small, and the larger ions cannot fit in. In some embodiments, anions, such as Cl" and SO4 ² ", cannot enter the organic liquid phase either, because otherwise the charge neutrality of the organic phase will be violated. The net cathodic reaction is

Li ⁺ (aq) + e" = Li (s).

[0064] The anodic reaction can depend on the composition of the brine. If the anion is predominantly SO4 ² " and/or CO3 ² " the anodic reaction can be

2H ₂ O - 4e" = O ₂ f + 4H ⁺ ;

[0065] If the anion is predominantly Cl", the following electrochemical reaction may also occur:

2C1" - 2e" = Cht-

[0066] An advantage of the embodied methods is that liquid-liquid extraction and electrodeposition can occur together and produce lithium metal from brine in one step, leading to cost and energy savings compared to current multi-step processes. Moreover, the use of a lithium selective liquid layer according to embodiments disclosed herein has the following advantages over a design using a solid coating on the conductive substrate:

(1) As embodied in Fig. 4, if a small amount of water does transfer from the aqueous phase through the organic phase, and is reduced at the cathode, the evolved hydrogen may merely bubble up through the organic phase, causing no significant damage to the cathode. In contrast, as shown in Fig. 5, if hydrogen evolves on a cathode with a solid surface coating, the bubbles can damage the coating, leading to potentially catastrophic failure.

(2) Because liquid can simply be washed off of the conductive substrate for the embodiments of Figs. 2 and 3, electrolytically formed lithium metal is more easily recovered by the embodied methods than by methods using a solid coating.

[0067] According to the embodiments of Figs. 3 and 4, the organic liquid phase sits on the bottom of the cell, and is denser than the aqueous phase. An advantage of this configuration is that any gases that are released at the anode are free to bubble to the surface of the aqueous phase and escape without reacting with the layer of lithium metal 110 on the cathode, or causing unwanted mixing of the organic and aqueous phases.

[0068] As shown in the embodiment of Fig. 6, a different configuration can be used when the organic liquid phase is less dense than the aqueous phase. In this embodiment, the organic layer 204 can sit atop an aqueous phase 206 containing lithium salts. The organic layer 204 can be held in place on top of the aqueous phase 206 by impermeable barriers 212. Situated within the organic liquid phase can be a conductive substrate 202 onto which a lithium metal layer 210 can be deposited. As in the previous embodiments, the organic liquid phase 204 can be immiscible with water. In some embodiments, the organic liquid phase 204 can be unreactive with lithium metal. In other embodiments, the organic liquid phase 204 can form a stable solid electrolyte interface with the lithium metal layer 210. The organic liquid phase 204 can include a lithium salt, LiX, which is soluble in the organic liquid phase by virtue of the lithium cation Li ⁺ forming a complex Li(cr) ⁺ with a crown ether (cr) that selectively binds the Li ⁺ . The anion X" of the lithium salt can be an organic anion that is soluble in the organic liquid phase but not in water. Likewise, the crown ether can be soluble in the organic liquid phase but not in water.

[0069] In the embodiment of Fig. 6, the anode 208 can be situated away from the organic layer, in a part of the aqueous phase that is not coated with the organic layer, so that any bubbles of hydrogen gas 214 that form may not enter the organic layer 204 and may not contact the lithium metal layer 210. The cathode can be connected by an external circuit 216 to the conductive substrate 202, so that when voltage is applied, lithium ion can transport into the organic phase, forming a complex Li(cr) ⁺ with a crown ether (cr), and the Li(cr) ⁺ complex can cany the lithium ion to the surface of the cathode, there to be reduced to form the lithium metal layer 210.

[0070] In the embodiment of Fig. 7, the organic liquid phase containing the Li(cr)+ cation complex can be within an organogel 304, surrounding the conductive substrate 302, and submerged within a brine 306 containing lithium salts. An anode 308 can be situated away from the organogel 304, so that any bubbles of hydrogen gas 314 that form will not enter the organogel 204 and will not contact the lithium metal layer 310. The cathode can be connected by an external circuit 316 to the conductive substrate 302, so that when voltage is applied, lithium ion can transport into the organogel 304, forming a complex Li(cr) ⁺ with a crown ether (cr), and the Li(cr) ⁺ complex can cany the lithium ion to the surface of the cathode, there to be reduced to form the lithium metal layer 310.

[0071] In some embodiments, a cathode can comprise copper, aluminum, graphite coated copper, nickel, silicon, silver, carbon (e.g., rough-surface carbon, graphene), a lithophilic material, aluminum, gold, a copper alloy (Cu-Zn, Cu-Al, Cu-Sn), or any combination thereof. The anode can comprise a layer of lithium metal deposited thereon. Lithium metal can be deposited on the anode with a thickness of at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 pm. Lithium metal can be deposited on the anode with a thickness of at least about 1, 5, 10, 20, 30 9 40, 50, 100, 200, 300, 400, or 500 pm. Lithium metal can be deposited on the anode with a thickness of at most about 1, 5, 10, 20, 30, 40, 50, 100, 200, 300, 400, or 500 pm. Lithium metal can comprise a thickness between 1 and 380 pm, between 1 and 370 pm, between 1 and 360 pm, between 1 and 350 pm, between 1 and 340 pm, between 1 and 330 pm, between 1 and 320 pm, between 1 and 310 pm, between 1 and 300 pm, between 1 and 250 pm, between 1 and 200 pm, between 1 and 150 pm, between 1 and 100 pm, between 1 and 90 pm, between 1 and 80 pm, between 1 and 70 pm, between 1 and 60 pm, between 1 and 50 pm, between 1 and 45 pm, between 1 and 40 pm, between 1 and 35 pm, between 1 and 30 pm, between 1 and 25 pm, between 1 and 20 pm, between 1 and 15 pm, between 1 and 10 pm, or between 1 and 5 pm.

[0072] In some embodiments, a lithium metal electrode has a specific capacity of greater than about 3500, 3600, 3700, 3750, or 3800 mAh per gram. In some embodiments, a lithium metal electrode has a specific capacity of less than about 3600, 3700, 3750, or 3800 mAh per gram. The overall capacity of the lithium metal electrode (e.g., in basis of mAh) can be substantially matched with the capacity of the cathode. In some embodiments, a lithium metal electrode has a density of between about 0.4 g/cm ³ and about 0.534 g/cm ³ . In some embodiments, lithium metal electrode has a density of between about 0.45 g/cm ³ and about 0.543 g/cm ³ . In some embodiments, lithium metal electrode has a density of greater than 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, or 0.53 g/cm ³ . In some embodiments, lithium metal electrode has a density of less than 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, or 0.543 g/cm ³ .

[0073] Lithium metal can comprise less than 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of a non-metallic element. The ppm can be by mass or by count. The ppm can correspond to a basis used for the instrument to detect the non-metallic element. Lithium metal can comprise less than 5 parts-per-million (ppm) of non-metallic elements. In some embodiments, the lithium metal includes no more than 1 ppm of non-metallic elements by mass. The non-metallic element can be nitrogen, boron, oxygen, carbon, hydrogen, or fluorine. Non- metallic elements can be present as atomic species, or molecular species (e.g., as LisN, OH, lithium-boron compounds, carbonate, or O2). In some embodiments, a non-metallic element may form resistive material on a surface of the lithium metal. For example, LiCO3 or LiOH can create resistive losses for a lithium metal electrode. The presence of a non-metallic element can be detected using, for example, inductively coupled plasma optical emission spectroscopy (ICP- OES) or X-ray microtomography. The presence of a non-metallic elements may be detected using focused Ion Beam (FIB) with a secondary ion mass spectrometry (SIMS). The presence of a non-metallic elements may be detected using electron energy loss spectroscopy (EELS), and/or transmission electron microscopy (TEM), by detecting and mapping lithium via the high ionization cross-section of the shallow Li K-edge that is 10-100 times greater than those of other light elements, e.g., O and F.

[0074] Lithium metal can comprise less than 1500 ppm of a trace metal. Lithium metal can comprise less than 1400, 1300, 1200, 1100, 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of a trace metal. Lithium metal can comprise more than 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, or 5000 parts-per-billion (ppb) of a trace metal. The ppb can be by mass or by count. The ppb can correspond to a basis used for the instrument to detect the trace element. The trace metal can be aluminum, barium, calcium, chromium, iron, iridium, magnesium, tungsten, zinc, cobalt, or sodium. In some embodiments, a trace element may form an alloy with lithium. An alloy can reduce the capacity of a lithium metal electrode. Lithium metal can comprise less than 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of aluminum. Lithium metal can comprise less than 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of barium. Lithium metal can comprise less than 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of calcium. Lithium metal can comprise less than 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of chromium. Lithium metal can comprise less than 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of iron. Lithium metal can comprise less than 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of iridium. Lithium metal can comprise less than 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 5,040, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm of magnesium. Lithium metal can comprise less than 23, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of tungsten. Lithium metal can comprise less than 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of zinc. Lithium metal can comprise less than 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of sodium. Lithium metal can comprise less than 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ppm of cobalt. The presence of trace metals can be detected using, for example, inductively coupled plasma optical emission spectroscopy (ICP-OES).

[0075] Lithium metal can comprise a low density of structural impurities, e.g., subsurface structural impurities. Without being bound to a particular theory, elemental or molecular impurities in lithium metal may form phases which are distinct from a pure lithium phase. When current traverses through the lithium metal, the lithium metal may be heated. Higher temperature may permit impurities to conduct or diffuse in the lithium metal, which can lead to the formation of more stable phases of impurities in the lithium metal (e.g., crystallites). When such structural impurities (phases which have distinct crystal structures, or which have grain boundaries against lithium metal phases in the lithium metal) begin to form, they may continue to grow. Structural impurities can be detected by 3D techniques, e.g., X-ray tomography. Structural impurities may be present on the surface of lithium metal, or it may be present beneath the surface. The structural impurities can provide sites for dendrite nucleation or growth, and may crack the surrounding lithium metal. In some embodiments, the lithium metal can comprise less than 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 structural impurities/mm ³ . In some embodiments, the lithium metal can comprise less than 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 5,040, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm of structural impurities by weight.

[0076] The present disclosure provides computer systems that are programmed to implement methods of the disclosure. FIG. 8 shows a computer system 801 that is programmed or otherwise configured to extract lithium from a lithium resource. The computer system 801 can regulate various aspects of lithium extraction of the present disclosure, such as, for example, controlling, maintaining, or modulating applied electric potential to an electrochemical cell, and collecting measurements from sensors disposed in the electrochemical cell. The computer system 801 can be an electronic device of a user or a computer system that is remotely located with respect to the electronic device. The electronic device can be a mobile electronic device.

[0077] The computer system 801 includes a central processing unit (CPU, also “processor” and “computer processor” herein) 805, which can be a single core or multi core processor, or a plurality of processors for parallel processing. The computer system 801 also includes memory or memory location 810 (e.g., random-access memory, read-only memory, flash memory), electronic storage unit 815 (e.g., hard disk), communication interface 820 (e.g., network adapter) for communicating with one or more other systems, and peripheral devices 825, such as cache, other memory, data storage and/or electronic display adapters. The memory 810, storage unit 815, interface 820 and peripheral devices 825 are in communication with the CPU 805 through a communication bus (solid lines), such as a motherboard. The storage unit 815 can be a data storage unit (or data repository) for storing data. The computer system 801 can be operatively coupled to a computer network (“network”) 830 with the aid of the communication interface 820, The network 830 can be the Internet, an internet and/or extranet, or an intranet and/or extranet that is in communication with the Internet, The network 830 in some cases is a telecommunication and/or data network, The network 830 can include one or more computer servers, which can enable distributed computing, such as cloud computing. The network 830, in some cases with the aid of the computer system 801, can implement a peer-to- peer network, which may enable devices coupled to the computer system 801 to behave as a client or a server.

[0078] The CPU 805 can execute a sequence of machine-readable instructions, which can be embodied in a program or software. The instructions may be stored in a memory location, such as the memory 810. The instructions can be directed to the CPU 805, which can subsequently program or otherwise configure the CPU 805 to implement methods of the present disclosure. Examples of operations performed by the CPU 805 can include fetch, decode, execute, and writeback.

[0079] The CPU 805 can be part of a circuit, such as an integrated circuit. One or more other components of the system 801 can be included in the circuit. In some cases, the circuit is an application specific integrated circuit (ASIC).

[0080] The storage unit 815 can store files, such as drivers, libraries and saved programs. The storage unit 815 can store user data, e.g., user preferences and user programs. The computer system 801 in some cases can include one or more additional data storage units that are external to the computer system 801 , such as located on a remote server that is in communication with the computer system 801 through an intranet or the Internet.

[0081] The computer system 801 can communicate with one or more remote computer systems through the network 830. For instance, the computer system 801 can communicate with a remote computer system of a user. Examples of remote computer systems include personal computers (e.g., portable PC), slate or tablet PC’s (e.g., Apple® iPad, Samsung® Galaxy Tab), telephones, Smart phones (e.g., Apple® iPhone, Android-enabled device, Blackberry®), or personal digital assistants. The user can access the computer system 801 via the network 830.

[0082] Methods as described herein can be implemented by way of machine (e.g., computer processor) executable code stored on an electronic storage location of the computer system 801, such as, for example, on the memory 810 or electronic storage unit 815. The machine executable or machine readable code can be provided in the form of software. During use, the code can be executed by the processor 805. hi some cases, the code can be retrieved from the storage unit 815 and stored on the memory 810 for ready access by the processor 805. In some situations, the electronic storage unit 815 can be precluded, and machine-executable instructions are stored on memory 810.

[0083] The code can be pre-compiled and configured for use with a machine having a processer adapted to execute the code, or can be compiled during runtime. The code can be supplied in a programming language that can be selected to enable the code to execute in a precompiled or as-compiled fashion.

[0084] Aspects of the systems and methods provided herein, such as the computer system 801, can be embodied in programming. Various aspects of the technology may be thought of as “products” or “articles of manufacture” typically in the form of machine (or processor) executable code and/or associated data that is carried on or embodied in a type of machine readable medium. Machine-executable code can be stored on an electronic storage unit, such as memory (e.g., read-only memory, random-access memory, flash memory) or a hard disk. “Storage” type media can include any or all of the tangible memory of the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives and the like, which may provide non-transitory storage at any time for the software programming. All or portions of the software may at times be communicated through the Internet or various other telecommunication networks. Such communications, for example, may enable loading of the software from one computer or processor into another, for example, from a management server or host computer into the computer platform of an application server. Thus, another type of media that may bear the software elements includes optical, electrical and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links or the like, also may be considered as media bearing the software. As used herein, unless restricted to non-transitory, tangible “storage” media, terms such as computer or machine “readable medium” refer to any medium that participates in providing instructions to a processor for execution. [0085] Hence, a machine readable medium, such as computer-executable code, may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computers) or the like, such as may be used to implement the databases, etc. shown in the drawings. Volatile storage media include dynamic memory, such as main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise a bus within a computer system. Carrier-wave transmission media may take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer may read programming code and/or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.

[0086] The computer system 801 can include or be in communication with an electronic display 835 that comprises a user interface (UI) 840 for providing, for example, a user interface for monitoring the electrochemical cell. Examples of Ill’s include, without limitation, a graphical user interface (GUI) and web-based user interface.

[0087] Methods and systems of the present disclosure can be implemented by way of one or more algorithms. An algorithm can be implemented by way of software upon execution by the central processing unit 805.

[0088] The embodiments of the present disclosure described above are intended to be merely exemplary; numerous variations and modifications will be apparent to those skilled in the art. All such variations and modifications are intended to be within the scope of the present invention as defined in any appended claims. For instance, while some embodiments have been described using crown ether as the coordination compound, it shall be understood that other coordination compounds may suitably be used in place of or in combination with the crown ether. The present application provides embodiments of other coordination compounds, e.g., cryptands, nitrogen-containing cryptands, and orthoester cryptands, which can also be used lieu of, or in combination with, crown ethers to selectively coordinate lithium cations. [0089] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.