Toward New Technologies for the Production of Lithium

Lithium Overview Toward New Technologies for the Production of Lithium

Georges J. Kipouros and Donald R. Sadoway

The lightest of all metals, lithium is used Table II. Metals Production and Pricing Statistics in a variety of applications, including the production of organolithium compounds, as Fe Al Mg Ti Li an alloying addition to aluminum and mag- Production (t/y, 106) 752 21 0.35 0.0525 0.0125 nesium, and as the anode in rechargeable Price ($/kg) 0.45 1.50 3.96 19.82 89.43 lithium ion batteries. All of the world’s pri- Sales ($, 109) 338 31.5 1.39 1.04 1.12 mary lithium is produced by molten salt electrolysis. This article reviews the current sium the imminent possibility that its prices? Table III shows that aluminum is technology for lithium extraction and as- market distribution may be radically al- more abundant in the earth’s crust than sesses the prospects for change. tered by rapid growth in one applica- either iron or magnesium, yet steel is, by 9 INTRODUCTION tion: automotive die casting in the case far, the cheapest metal. So relative abun- of magnesium and anodes for recharge- dance does not explain pricing. How- With a density about half that of wa- able batteries in the case of lithium. It is ever, there is some correspondence be- ter, lithium (from the Greek “lithos,” curious that in the present lithium-ion tween the prices of steel and aluminum which means “stone”) boasts the lowest and the free energies of formation of density of all solids, a mere 0.53 g/cm3 at their oxides.10 Magnesium, titanium, and 20°C. Its electronic configuration is Lithium shares with lithium do not fit this pattern, largely 1s2␣2s1; its atomic number is 3; and its magnesium the due to the much smaller tonnages in- atomic mass is 6.941 g/mol. Typical of volved. As tonnages rise, making more alkali metals, lithium’s crystal structure imminent possibility efficient use of capital, prices of these is body-centered cubic. The element re- that its market latter three metals can be expected to acts with water (and moisture in the air) fall. Nicholson’s review of the pricing to produce the hydroxide, LiOH, and distribution may be history of lithium shows that from 1964 hydrogen gas. Unlike the heavier alka- to 1996, the price of this metal rose 23 lis, lithium does not react violently with radically altered by percent in constant dollars.7 However, oxygen; indeed, the metal is stable in dry rapid growth in one the effects of the drop in price of lithium air when the dew point is maintained carbonate in South America and the below –38°C. application: growing demand for lithium in recharge- Lithium is not a structural metal; in automotive die able batteries have yet to be felt by the the majority of its applications, it func- market. tions as a chemical reagent. Table I com- casting in the case LITHIUM METALLURGY pares the properties of lithium with those of steel and aluminum, the dominant of magnesium and With regard to the metallurgy of structural metals, and with those of mag- anodes for lithium,11–14 the metal is found in nature nesium and titanium, both considered as hard rock ore and as brine. The strat- too pricey for mainstream structural rechargeable egy for reducing these resources to metal applications.1 Table II reports world pro- batteries in the involves conversion to carbonate, then duction figures for these five metals.2–4 to chloride, followed by molten salt elec-

Even though the world production of case of lithium. trolysis. Spodumene (LiAlSi2O6) is one lithium amounts to only 12,500 tonnes example of a hard rock resource. Con- per year, the high unit price of the metal battery,6 we find compounds of lithium version to carbonate involves either al- translates into annual sales of approxi- and cobalt, two of the four metals (the kaline fusion and carbonation or acid mately $1␣ billion and, thus, puts the value other two are gold and magnesium) for roasting, calcination, and carbonation. of the world lithium industry at par with which prices have risen over the past The double salt KLiSO4 is one example that of titanium and magnesium. Harben 30 years (after adjustments for inflation).7 of a brine resource. Conversion to car- and Edwards have reported upon trends In response, considerable effort is being bonate involves purification (removal of in the global lithium industry, which directed at displacing cobalt-bearing potassium) and precipitation. Potential they characterize as being in a state of compounds.8 methods to win lithium from pegmatites, rapid flux.5 Lithium shares with magne- Is there a scientific basis for metal natural brines, and clays have been discussed.15–17 The carbonate is then con- Table I. Properties of Selected Metals verted to the chloride with the action of a chlorinating agent such as hydrogen Fe Al Mg Ti Li chloride. Table IV gives the salient fea- Melting Point (°C) 1,535 660 650 1,660 180 ° tures of the electrolytic reduction pro- Boiling Point ( C) 2,860 2,518 1,093 3,287 1,347 cess. The cell has a central cathode of Density (g/cm3) 7.87 2.70 1.74 4.54 0.53 E (GPa) 211 71 45 120 5 mild steel on which lithium is produced in liquid form. Opposing graphite plates

24 JOM • May 1998 serve as the anodes on which chlorine evolves. A bell-shaped structure posi- Table IV. The Electrolytic Production of Lithium tioned above the cathode collects the Electrolyte LiCl–KCl eutectic Feed LiCl rising liquid metal and prevents it from ° reacting with the chlorine gas which also Temperature 400–460 C Anode Carbon rises. Anhydrous lithium chloride is the Cathode Mild Steel cell feed. Potassium chloride is the sol- → ° Overall Cell Reaction LiCl (l) Li (l) + 1/2 Cl2 (g) for which E 427°C = 3.6 V vent and supporting electrolyte because – → – Anode Cl 1/2 Cl2 (g) + e it alone, among the common alkali and Cathode Li+ + e– → Li (l) alkaline-earth chlorides, has a decom- Current Density 2 A/cm2 position potential that is more extreme Energy Consumption 35 kWh/kg than that of lithium chloride. Put an- other way, electrolysis of a melt com- Table V. Reactions for the Production of Lithium by Thermochemical Reduction prising LiCl-NaCl will produce lithium metal containing a substantial amount Carbothermic Reduction Li O + C → 2 Li (g) + CO (lithia feed, carbon reductant) of sodium, which is highly undesirable 2 6 LiOH + 2 C → 2 Li (g) + 2 Li CO + 3 H (LiOH feed, carbon reductant) if lithium is to be used in battery applica- 2 3 2 3 LiOH + FeC → 3 Li (g) + Fe + 3/2 H + CO + CO (LiOH feed, iron carbide reductant) tions. The electrolysis temperature is 2 2 2 governed by the physical chemistry of Metallothermic Reduction of the Oxide → the molten salt. The eutectic point of 2 Li2O + 2 CaO + Si 4 Li (g) + Ca2SiO4 (c.f., Pidgeon process) 3 Li O + 2 Al → 6 Li (g) + Al O LiCl-KCl is 350°C and 42 mole percent 2 2 3 KCl.18 At 400°C, the liquid range extends Metallothermic Reduction of the Hydroxide from about 35–45 mole percent KCl. At 2 LiOH + 2 Mg → 2 Li (g) + 2 MgO + H → 2 this temperature lithium metal is mol- 2 LiOH + Al Li (g) + LiAlO2 ten, but its vapor pressure is acceptably Electrolytic-Calciothermic Reduction of the Oxide low. Operational data for the electroly- Cathode Ca2+ + 2 e– → Ca → sis cells may be found elsewhere in the Ca + Li2O CaO + 2 Li 14 2– → – literature. Anode O + 1/2 C 1/2 CO2 + 2 e What are the challenges and opportu- or 2– → – nities for lithium extraction? Certainly, O 1/2 O2 + 2 e there is the need for new electrode materials. Avoiding the use of carbon would an amalgam intermediate by the elec- of feedstocks and carbothermic reduc- make the process environmentally trolysis of an aqueous solution of lithium tants. Metallothermic reduction is also a friendlier and might even enable the hydroxide. Lithium metal is then pro- possible route to metal. Also shown are design of a long-lived bipolar cell. One duced by electrorefining the amalgam at reactions for the reduction of lithium of the authors has enunciated criteria for 225°C in a cell containing an electrolyte oxide by silicon and aluminum. Some the selection of materials that can serve of molten LiI-CsI eutectic.22 experimental data taken under Pidgeon- like conditions have been reported.28 as inert anodes in Hall-Héroult cells pro- PARADIGM SHIFTS ducing aluminum.19 Metal alloys con- Table V continues with reactions for the sisting of a base metal (or metals) plus What about radical innovation (i.e., reduction of lithium hydroxide by mag- aluminum have been identified as the totally different reduction chemistry)? nesium and aluminum. Calcium can also most promising materials.20 Perhaps it is Here is a short list of candidates, none of reduce lithium oxide to metal. A novel time to apply these concepts to lithium which is in commercial use: electrolysis concept that combines electrolysis and electrolysis. Installing cathodes made of of carbonate feed, carbothermic reduc- metallothermic reduction is given in the a material that is wetted by molten tion, metallothermic reduction, electro- table as well. The process involves in- lithium would afford new opportunities lytic-calciothermic reduction, and elec- situ generation of calcium from a bath of in cell design. In aluminum reduction trolysis of lithia from an oxide melt. Elec- calcium oxide and calcium chloride into cells, the material showing the most trolysis of carbonate feed would elimi- which one adds lithium oxide. At the promise is titanium diboride, which has nate the chlorination step. There are re- cathode, the product of electrolysis is graduated from laboratory testing to in- ports of laboratory-scale tests,23,24 and a calcium metal, which chemically reduces stallation in industrial cells for long-term patent has been granted.25 Carbothermic lithia added to the bath. At the anode, performance assessment.21 There is also reduction has been studied many times one has the choice of either a consum-

a need for a new process for preparing in the past with other metals such as able anode producing CO/CO2 or a non- anhydrous lithium chloride in a manner aluminum and magnesium, but has consumable anode producing oxygen. that is energy efficient and gives a prod- never been shown to be a commercial The process can be viewed as calcio- uct of high purity. Alternatively, new success.26,27 However, in view of the much thermic reduction of lithium oxide com- electrolyte chemistries that do not re- higher price of lithium, it may be pos- bined with the in-situ generation of the quire conversion to chloride might prove sible to make carbothermic reduction calcium reductant. Lastly, there is elec- to be attractive. For example, lithium economically viable. Table␣ V shows three trolysis of lithium oxide from an all- metal has reportedly been produced as candidate reactions involving a variety oxide electrolyte. The concept is com- plete aversion of carbon and chlorine Table III. Properties of Selected Metals chemistries. Lithium oxide is broken di- Fe Al Mg Ti Li rectly into its constituent lithium and oxygen. Obviously, there are major tech- Price ($/kg) 0.45 1.50 3.96 19.82 89.43 nical obstacles to overcome. However, if Abundance Percent 4.1 8.2 2.3 0.56 0.002 it can be shown to be viable, the process Rank 4 3 7 9 31 would be environmentally sound and 29 Free Energies of Formation of the Oxides, M O long-term sustainable. Ironically, elec- x y trolysis of the oxide was the method by kJ/mol O2 503 1,055 1,138 899 1,124 kJ/g M 6.7 29 23 18 40 which Davy and Brandé in 1818 produced the first lithium metal.

1998 May • JOM 25 Processes for Lithium from Ores and Brines,” Energy, 3 the Department of Mining and Metallurgical CONCLUSIONS (1978), pp. 305–313. 17. R.H. Lien, “Lithium Recovery from McDermitt, NV Engineering of DalTech—Dalhousie Univer- The demand for lithium metal and for Clays,” Light Metals 1988, ed. L.G. Boxall (Warrendale, PA: sity. Dr. Kipouros is also a member of TMS. TMS, 1988), pp. 783–797. new lithium compounds will continue 18. E. Elchardus and P. Laffitte, Bull. Soc. Chim., France, 51 Donald R. Sadoway earned his Ph.D. in to grow. Environmental concerns (1932), pp. 1572–1579. chemical metallurgy at the University of 19. D.R.␣ Sadoway, “A Materials Systems Approach to Selec- coupled with the shift in resource chem- tion and Testing of Nonconsumable Anodes for the Hall Toronto in 1977. He is currently a professor of istries will provide incentives for the Cell,” Light Metals 1990, ed. C.A.␣ Bickert (Warrendale␣ PA: materials chemistry in the Department of TMS, 1990), pp.␣ 403–407. search for new extraction technology, 20. J.N. Hryn and D.R. Sadoway, “Cell Testing of Metal Materials Science and Engineering at Massa- which will predictably involve a new Anodes for Aluminum Electrolysis,” Light Metals 1993, ed. chusetts Institute of Technology. Dr. Sadoway S.K. Das (Warrendale␣ PA: TMS, 1993), pp. 475–483. is also a member of TMS. application of molten salt chemistry. 21. H. Zhang, V. de Nora, and J.A. Sekhar, Materials Used in the Hall-Héroult Cell for Aluminum Production (Warrendale␣ PA: References TMS, 1994), pp. 37–42. For more information, contact Donald R. 22. J.F. Cooper et al., “Development of a Bipolar Cell for Sadoway, Massachusetts Institute of Technol- 1. Smithells Metals Reference Book, 6, ed. E.A. Brandes (Lon- Lithium Production,” Fundamentals of Electrochemical Process don: Butterworths, 1983). Design: A Tutorial and Anodic Processes: Fundamental and ogy, Department of Materials Science and Engi- 2. Iron & Steelmaker, 24 (13) (1997), p. 2. Applied Aspects, 0095-11, ed. J.B. Talbot et al. (Pennington, NJ: neering, Room 8-109, 77 Massachusetts Ave., 3. Light Metal Age, 55 (1,2) (1997), p. 8. Electrochemical Society, 1995, pp. 280–290. Cambridge, Massachusetts 02139-4307; fax (617) 4. U.S. Geological Survey, Mineral Commodity Summaries, 2 23. W.H. Kruesi and D.J. Fray, “Fundamental Study of the 253-5418; e-mail [email protected]. (1997). Anodic and Cathodic Reactions during the Electrolysis of a 5. P.W. Harben and G.H. Edwards, JOM, 6 (1997), p. 21. Lithium Carbonate-Lithium Chloride Melt Using a Carbon 6. For a description of the workings of a rechargeable lithium Anode,” J. Appl. Electrochem., 24 (1994), pp. 1102–1108. ion battery, the reader is directed to an article by G. Ceder, A. 24. J.L. Smith, “Electrochemical Production of Lithium Metal Van der Ven, and M.K. Aydinol, which will appear in JOM from Lithium Oxide in Molten Lithium Chloride” (Paper later this year (Reference 8). presented at 1998 TMS Meeting, San Antonio, TX, 16–19 Coming in June’s 7. P. Nicholson, JOM, 50 (5) (1998), pp. 27–30. February 1998). 8. G. Ceder, A. Van der Ven, and M.K. Aydinol, JOM, 25. DeYoung, “Production of Lithium by Direct Electrolysis accepted for publication in volume 50. of Lithium Carbonate,” U.S. patent 4,988,417 (29 January JOM: 9. J. Emsley, The Elements, 2 (Oxford, U.K.: Clarendon Press, 1991). 1991). 26. J.P. McGeer, “Alternate Methods for the Production of 10. M.W. Chase et al., JANAF Thermochemical Tables, 3 (New Aluminum Metal,” Proceedings of a conversazione on “The • The Hot Deformation York: American Institute of Physics, 1985). Production of Liquid Aluminum,” series 25-7, (2) ed. E.␣ Ozberk, 11. W. Edward Cowley, “The Alkali Metals,” Molten Salt D.W.␣ Macmillan, and R.I.L.␣ Guthrie (Montreal: TMS-CIM, of Aluminum and Technology, ed. D.G. Lovering (New York: Plenum 1982), pp. 1986), pp.␣ 125–139. 57–90. 27. K. Grjotheim and J.B. See, Minerals Sci. Engng., 11 (2) Its Alloys 12. C.W. Kamienski, D.P. McDonald, and M.W. Stark, (1979), pp. 80–98. “Lithium and Lithium Compounds,” Kirk-Othmer Encyclope- 28. A.A.J. Smeets and D.J. Fray, “Extraction of Lithium by dia of Chemical Technology, 15 (New York: Wiley, 1995), pp. Vacuum Thermal Reduction withAluminum and Silicon,” • Advances in Thermal 434–463. Trans. Inst. Min. Metall., 100 (1991), pp. C42–C54. 13. R.J. Bauer, “Lithium and Lithium Compounds,” Ullmann’s 29. D.R. Sadoway, J. Mater. Res., 10 (1995), pp. 487–492. Management for Encyclopedia of Industrial Chemistry, A 15 (Weinheim: VCH Publishers, 1984), pp. 393–414. 14. C.A. Hampel, “Lithium Electrowinning,” Encyclopedia of ABOUT THE AUTHORS Electronic Materials Electrochemistry, ed. C.A. Hampel (Huntington, NY: Krieger, 1972), pp. 778–779. Georges J. Kipouros earned his Ph.D. in 15. P. Mahi et al., “Lithium-Metal of the Future,” JOM, 38 (11) • TMS Annual Report (1986), pp. 20–26. mining and metallurgical engineering at the 16. W.A. Averill and D.L. Olson, “A Review of Extractive University of Toronto. He is currently head of T S ALUMINUM ALLOYS Minerals ¥ Metals ¥ Materials FOR PACKAGING IV A specialty symposium to be held as part of the ANNOUNCINGiego 1999 TMS Annual Meeting & Exhibition in San D San Diego, California, February 28 - March 4, 1999

The 128th TMS Annual Meeting & Exhibition Sponsored by the Aluminum Committee of The Minerals, Metals & Materials Society’s (TMS’s) Light Metals Division

This symposium is the fourth in a series of symposia organized to provide with the conference organizers. If you have questions or need assistance a comprehensive forum where the latest science and technology of while using the CMS, please contact TMS Technical Programming aluminum can stock, lid stock, and tab stock alloys; coatings; and their Services at (724) 776-9000, ext. 237 or 227. related applications to can, lid, and tab making could be presented. If you do not have access to the World Wide Web, please submit your Topics to be discussed at this symposium include the physical and abstract to: Dr. Subodh Das, ARCO Aluminum, Inc., 2900 National City process metallurgy of aluminum packaging materials (rigid container Tower, P.O. Box 32860, Louisville, KY 40232 U.S.A.; Telephone: (502) sheets, flexible packaging, and food container) using direct-chill or 566-5756; Fax: (502) 566-5740; E-mail: [email protected]. continuous casting processes, alloy processing, structure and property characterization, package design, technology, and performance. For more information on this symposium and the 1999 TMS Annual Meeting & Exhibition, please contact: Abstract Submission TMS Customer Service All prospective authors are invited to submit a 150-word abstract by July 420 Commonwealth Drive 1, 1998 using the TMS Conference Management System (CMS). The Warrendale, PA 15086-7514 CMS will allow anyone with a World Wide Web browser to electronically Telephone: 1-800-759-4867 or (724) 776-9000, ext. 270 submit an abstract. Access the web site at http://www.tms.org/cms. Follow Fax: (724) 776-3770 the easy instructions for electronic submission and direct communication E-mail: [email protected]

Information on this and all TMS-sponsored and co-sponsored conferences is available via the World Wide Web at http://www.tms.org/Meetings/Meetings.html.

26 JOM • May 1998