Selective Lithium Extraction from Brines by Chemical Reaction with Battery Materials

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Intrnont, Normon; University of Southmpton, Chemistry Grci-Arez, Nuri; University of Southmpton, Hector, Andrew; University of Southmpton,

1 Journl of Mterils Chemistry A Selective Lithium Extrction from Brines by Chemicl Rection with Bttery Mterils Journl: Journl of Mterils Chemistry A Mnuscript ID: TA-COM Article Type: Communiction Dte Submitted by the Author: 04-Mr-14 Complete List of Authors: Intrnont, Normon; University of Southmpton, Chemistry Grci-Arez, Nuri; University of Southmpton, Hector, Andrew; University of Southmpton, School of Chemistry Milton, Andy; University of Southmpton, Ntionl Ocenogrphy Centre Owen, J; University of Southmpton, Deprtment of Chemistry

2 Pge 1 of 5 Journl Nme Journl of Mterils Chemistry A Dynmic Article Links Cite this: DOI: /c0xx00000x ARTICLE TYPE Selective Lithium Extrction from Brines by Chemicl Rection with Bttery Mterils Normon Intrnont, Nuri Grci-Arez, *, Andrew L. Hector, Andy Milton b nd John R. Owen, * Received (in XXX, XXX) Xth XXXXXXXXX XX, Accepted Xth XXXXXXXXX XX 5 DOI: /b000000x We demonstrte fst nd efficient chemicl redox insertion of lithium ions into solid FePO 4 from lithium slt solutions contminted with other ctions. The method is illustrted with sodium thiosulfte, N 2 S 2 O 3, s reducing gent tht is found to hve n optimum redox potentil for this rection. The method shows very high selectivity for lithium extrction; enrichment in lithium concentrtion vs. other ions of more thn 0 is chieved under the conditions relevnt to lithium extrction from brines. It is cler the Erth contins enough lithium to supply lithium btteries for widespred use in electric vehicles; wht is debteble is which resources cn be used nd t wht cost. Lithium extrction from the lrgest deposits is currently too complex, slow nd inefficient to be economicl 1,2. This is minly becuse the high cost of extrcting lithium from chloride-bsed brines, in which lithium is diluted by up to 1:100 by mss in other metl ions such s sodium, mgnesium nd potssium 3. Recycling of lithium is n ttrctive ide tht is ripe for reserch nd development. In both cses the requirement is n inexpensive process for concentrting nd refining lithium from dilute sources contining other metl ctions. Current lithium extrction from slt lke brines involves preconcentrtion by evportion for months, followed by tretment with lime (CO) to remove mgnesium nd sodium crbonte (N 2 CO 3 ) to precipitte out lithium crbonte 2,4,5. In ddition to being slow, the process only recovers round % of the lithium, nd it is unsuitble in the presence of high concentrtions of mgnesium nd sulphte. Another method bsed on ion exchnge techniques uses mngnese dioxide s lithium-ion bsorbent or lithium-ion sieve, but the process is usully not limited to Li + -H + exchnge rection; redox rections cusing the dissolution of mngnese ions from the dsorbent during the cid tretment lso tke plce, nd hence, the dsorbent is difficult to reuse A few recent studies investigted lithium extrction by ppliction of n electric current between two bttery electrodes, but tht pproch requires lrge-re electrodes nd smll solution volume nd it is very time consuming due to the slow diffusion of highly diluted ions The process investigted here involves the topotctic insertion of lithium ctions into heterosite FePO 4 from lithium slt solution, which is the dischrge rection for the well-known lithium iron phosphte rechrgeble bttery. The product, crystlline LiFePO 4 in the olivine phse is more stble thn its sodium nlogue (sodium insertion tkes plce t 0 mv less positive potentils 11 ), suggesting tht the FePO 4 lttice my ccept lithium in preference to other ctions on exposure to lithium slt solutions contminted with other ctions. An enhncement of the proportion of lithium in the structure reltive to other mobile ctions in solution my lso be chieved kineticlly becuse of the high mobility of lithium in the structure, s shown in fst dischrge rections; this suggests tht lithium my be selected by controlling the time of exposure of FePO 4 to contminted lithium slt solutions. Indeed, sodium insertion into heterosite FePO 4 involves lrge volumetric expnsion, structurl rerrngement nd slow kinetics In ddition, the presence of smll mount of lithium ions in the FePO 4 mtrix seems to block the insertion of sodium. 17 Previous demonstrtions of lithium insertion nd extrction on FePO 4 hve been electrochemicl, including the cse where sodium ws delibertely introduced 11, In this work, we demonstrte tht lithium ions cn be selectively extrcted from brines by chemicl insertion into FePO 4. This pproch overcomes some of the limittions of the electrochemicl method, such s the slow rte of diffusion of lithium ctions in solution into n electrode structure t low concentrtions, ohmic drop losses nd interference of side rections such s wter electrolysis. As we will show below, the chemicl pproch is fst nd esy one-pot process tht ppers to be esy to scle up. In this work, we hve demonstrted the concept with sodium thiosulfte s mild, wter-stble reducing gent (Rection 1) tht provides the driving force for lithium insertion into FePO 4 (Rection 2). The overll chemicl rection (Rection 3) is therefore investigted s n lterntive to electrochemicl lithium insertion into FePO 4 s selective bsorbent S 2 O 3 S 4 O 6 + 2e - E 0 =0.08V vs. SHE 18 (1) Li + + FePO 4 + e - LiFePO 4 E 0 = 0.4V vs. SHE 11 (2) 2Li FePO 4 + 2S 2 O 3 S 4 O LiFePO 4 (3) This journl is The Royl Society of Chemistry [yer] [journl], [yer], [vol],

3 Journl of Mterils Chemistry A Pge 2 of To complete the process, the lithium is recovered s lithium sulfte solution, using potssium persulfte s the oxidnt ccording to eqution (4) s previously described 19. Alterntively the LiFePO 4 product my be used directly in lithium ion bttery. Both pproches re considered in this work. 2LiFePO 4 +K 2 S 2 O 8 2FePO 4 + Li 2 SO 4 + K 2 SO 4 (4) The ims of this work re: 1. to determine the rte of lithium extrction from lithium slt solutions s function of concentrtion of lithium nd thiosulfte. 2. to mesure the rtio of lithium to other ctions inserted into the structure s function of the rtio in solution. 3. to demonstrte effective cycling of regenerted LiFePO 4 s positive lithium ion bttery electrode. The kinetics of lithition of FePO 4 from queous Li + The formtion of LiFePO 4 by lithium insertion into FePO 4 from vrious solutions ws ttempted with 4-fold molr excess of the solution regent over the solid bsorbnt. 1g smples of the wshed, dried product were tken nd chrcterised by X-ry diffrction (XRD). Fig. 1 is n exmple of the XRD pttern of prtilly lithited product, showing the presence of both heterosite FePO 4 nd olivine LiFePO 4 structures (Fig. S1). Rietveld refinement of the dt provides n estimte of the extent of lithition, s defined s the phse % of the olivine vs. the heterosite structures (Tble 1). s estimted from XRD (), electrochemicl (b) nd ICP (c) 60 mesurements. [Li 2SO 4] 5min min 60min 1min 240min 600min 1.5M b 0.10 c 0.M M M b 0. b 0.41 b 0.82 b 1.02 b 1.02 b 1.10 b c b 0.04 b 0.28 b b 0.03 c c 0.86 b 1.00 b 1.00 b 1.02 b c b 0.47 c b 1.01 b 0.01 b 0.05 b 0.04 b 0.12 b 0. b c An independent estimtion of the extent of lithition ws obtined by electrochemicl mesurements. The powder smples were mde into lithium ion cthodes by mixing with binder nd conductive dditive then incorported into cells with lithium nodes. Electrochemicl potentiometric titrtion ws used to determine the molr lithium deficiency with respect to LiFePO 4 ccording to Frdy s lw (Fig. S2). This could be done by either oxidtive removl of lithium or by the reductive insertion of lithium, both methods providing consisting results. Fig. 2 illustrtes n exmple of the glvnosttic removl of lithium, where higher vlues of the specific chrge re ssocited with higher molr lithium content, nd Tble 1 summrizes the resulting vlues Fig.1. Fit to XRD dt of Li x FePO 4 obtined by lithition of FePO 4 with 0.7M N 2 S 2 O M Li 2 SO 4 for 1 minutes. Blck line is the experimentl dt, red line is the fit nd blue line is the difference. Upper tick mrks nd show the llowed reflection positions for LiFePO 4 nd lower tick mrks nd for FePO 4. Tble 1. Lithium molr content of Li x FePO 4 smples obtined by lithition of FePO 4 with 4-fold excess of regent (Li 2 SO 4 + N 2 S 2 O 3 in molr rtio 1:2) for different times, s indicted, Fig. 2 Potentiometric titrtion of Li x FePO 4 electrodes prepred with the rection product of FePO 4 in 0.7M N 2 S 2 O M Li 2 SO 4 for different times, s indicted. Specific current: 17 ma/g (C/10). A third estimtion of the lithium content in the Li x FePO 4 rection product ws obtined by digesting the product with 0.2M HNO M HCl in order to dissolve Li x FePO 4 into xli + + Fe 3+ + PO 3-4. The solution ws then diluted nd exmined by ICP-MS to give the lithium concentrtion, from which the lithium molr frction in the solid smple ws clculted (Tble 1). 2 Journl Nme, [yer], [vol], This journl is The Royl Society of Chemistry [yer]

4 Pge 3 of 5 Journl of Mterils Chemistry A Tble 1 clerly shows tht lithition FePO 4 to form LiFePO 4 occurs reltively quickly in queous solution. This corresponds to lithium uptke of mg of Li + per grm of FePO 4 solid bsorbent. This vlue of the lithium uptke is much higher thn tht obtined with most other types of bsorbents, with the exception of some dvnced mngnese oxide ion-sieves tht bsorbed up to mg Li per grm of bsorbnt. -23 In ddition, it is cler from Tble 1 tht consistent vlues of the lithium content re obtined from ll three methods. This strongly indictes tht contmintion of the smple with other ctions (sodium) is only minor, since sodium inserted in FePO 4 would contribute to the electrochemicl mesurements but not to the ICP-MS nlysis. Furthermore, olivine NFePO 4 would led to dditionl reflection positions in the XRD pttern (Fig. S3). A more quntittive nlysis of the lithium selectivity is presented below. From the experiments presented here it cn be seen tht, for exmple, complete lithium insertion in less thn 3 hours requires [Li + ]>0.7M nd [S 2 O 2-3 ]>0.7M. The kinetic nlysis of the results (Fig. S4) suggests rection rte which is first order with respect to both lithium nd thiosulfte concentrtions with n overll second order rte constnt of round 0.03 min -1 M -2. It is lso importnt to point out tht the process of lithium insertion nd extrction from FePO 4 could be repeted severl times without noticeble chnges in the structurl stbility of the dsorbnt (Fig. S5). Determintion of the lithium selectivity In the previous section, we hve shown tht one cn form LiFePO 4 from FePO 4 in lithium-contining solutions. Here, we will nlyse the presence of contminnt ions, such s sodium, mgnesium nd potssium, in the rection product. For tht purpose, we hve performed chemicl nlysis of the solid products vi digestion of the solid followed by ICP- MS nlysis. First of ll, we studied the contmintion by sodium ions from solutions of high sodium concentrtions. We performed the lithition of FePO 4 in solutions with [Li + ] to [N + ] rtios vrying between 0.1 nd 0.01 with moderte concentrtion of reducing gent, [S 2 O 2-3 ]=0.3M. Tble 2 shows the results of the lithium nd sodium uptke, s well s the lithium selectivity, s defined s the rtio of lithium to sodium molr concentrtions in the solid vs. tht in the solution. As presented in Tble 2, the composition of the solid is reltively insensitive to the presence of n excess of sodium ctions in solution, resulting in remrkbly high lithium selectivities s the sodium concentrtion in solution increses. Tble 2. Li nd N concentrtions of smples obtined by tretment of 1g FePO 4 for 24 hours with [N 2 S 2 O 3 ]=0.3M + [LiCl]=0.06M + [NCl]=5.4M, 2.4M b, or 0M c. [Li + ]:[N + ] solution Li uptke (mg/g) N uptke (mg/g) [Li + ]:[N + ] solid Lithium selectivity 1/ / b /10 c We then studied the selectivity towrds lithium insertion obtined with solutions contining lithium, sodium, potssium nd mgnesium ctions in the concentrtions observed in nturl brines in one of the lrgest lithium reserves in the world (Centrl Altiplno, Bolivi) 3. Tble 3 demonstrtes tht full lithition of FePO 4 cn be chieved under those conditions, with remrkble vlues of the mount of lithium bsorbed (round 46 mg/g). Furthermore, the uptke of other ions is very smll, nd smller thn tht reported for mngnese oxide sieves.,22- In conclusion, the method hs very high selectivity towrds lithium, leding to n enrichment in lithium concentrtion vs. other ions of >0 under the conditions relevnt to lithium extrction from brines. Since we hve observed tht the finl composition of the LiFePO 4 rection product is not very sensitive to the concentrtion of ions in solution, it is expected tht the lithium selectivity will only increse s the concentrtion of lithium in solution is mde much smller thn tht of other ions. Figs. S6-7 show the XRD pttern nd electrochemicl chrcteriztion of the smples, confirming LiFePO 4 formtion from nturl brines nd the bsence of detectble contminnts. Tble 3. Li, N, K nd Mg concentrtions of smples obtined by: ) 0.6g FePO 4 with [N 2 S 2 O 3 ]=0.3M + [LiCl]=0.06M + [NCl]=4M + [KCl]=0.2M + [MgCl 2 ]=0.3M for 24 hours; b) 1g FePO 4 with [N 2 S 2 O 3 ]=0.3M + [LiCl]=0.2M + [NCl]=2.4M + [K 2 SO 4 ]=0.3M + [MgCl 2 ]=1.3M for 24 hours. [M] stnds for the molr concentrtion of the metl ction referred in ech row, i.e. N +, K + or Mg 2+. Me Li + Uptke (mg/g).7 [Li + ]:[M] solution [Li + ]:[M] solid Lithium N / K / Mg / Li b N b 1/15 3 K b 1/ Mg b 1/ selectivity Electrochemicl cycling of regenerted electrodes Finlly, we tested the pplicbility of the method for recycling of bttery mterils in nturl brines. We prepred lithium ion electrodes with LiFePO 4 obtined by regenerting FePO 4 with 90 brines. Fig. 3 shows the results of the electrochemicl cycling t different rtes. The difference in the chrge delivered by the commercil nd the recycled LiFePO 4 electrodes is smller thn the reproducibility of these mesurements, except for the cse of the electrode lithited in brine type b t fst cycling 95 rtes, which provides smller chrges. Conclusions We hve demonstrted the following: This journl is The Royl Society of Chemistry [yer] Journl Nme, [yer], [vol],

5 Journl of Mterils Chemistry A Pge 4 of 5 1. The kinetics of lithium extrction by FePO 4 from queous slt solutions cn be described with n overll second order rte constnt of 0.03 min -1 M The mount of lithium inserted in LiFePO 4 cn be s 5 high s 46 mg Li per grm of solid. 3. The uptke of other ions such s sodium, potssium nd mgnesium is <3 mg per grm of solid. 4. Recycled LiFePO 4 ws found to give stisfctory performnce s positive lithium ion bttery 10 electrode. These conclusions hve importnt implictions for both lithium extrction nd recycling. This work demonstrtes low cost route to concentrte nd purify lithium slts from diluted nd contminted precursors such s nturl brines 15 nd products of recycling. Fig 3. Electrochemicl cycling of LiFePO 4 t different cycling rtes, s indicted. : electrodes prepred with LiFePO 4 35 (Ttung). : 0.6g FePO 4 with [N 2 S 2 O 3 ]=0.3M + brine type : [LiCl]=0.06M + [NCl]=4M + [KCl]=0.2M + [MgCl 2 ]=0.3M for 24 hours. : 1g FePO 4 with [N 2 S 2 O 3 ]=0.3M + brine type b: [LiCl]=0.2M + [NCl]=2.4M + [K 2 SO 4 ]=0.3M + [MgCl 2 ]=1.3M. Closed symbols: chrge; 40 open symbols: dischrge. Acknowledgements The uthors would like to thnk the Ministry of Science nd Technology, Royl Thi Government for funding Normon Intrnont s PhD reserch. Notes nd references: Chemistry, University of Southmpton, UK. E-mil: N.Grci- Arez@soton.c.uk, J.R.Owen@soton.c.uk b Ocen nd Erth Science, Ntionl Ocenogrphy Centre Southmpton, UK. Electronic Supplementry Informtion (ESI) vilble: experimentl detils nd supplementry figures. See DOI: /b000000x/ 1. L. T. Peiro, G. V. Mendez nd R. U. Ayres, Jom, 13,, D. E. Grrett, Hndbook of lithium nd nturl clcium chloride: their deposits, processing, uses nd properties, Elsevier Acdemic Press, Amsterdm, Boston, F. Rischer nd B. Fritz, Chemicl Geology, 1991, 90, L. Moreno, Lithium Industry, A Strtegic Energy Metl - Significnt Increse in Demnd Ahed, W. Thil, The Trouble with Lithium. Implictions of Future PHEV Production for Lithium Demnd, V. V. Volkin, G. V. Leontev nd S. A. Onolin, Neorg. Mter., 1973, 9, J. C. Hunter, Journl of Solid Stte Chemistry, 1981, 39, X. M. Shen nd A. Clerfield, Journl of Solid Stte Chemistry, 1986, 64, K. Ooi, Y. Miyi nd S. Ktoh, Seprtion Science nd Technology, 1986, 21, K. Ooi, Y. Miyi nd S. Ktoh, Solvent Extrction nd Ion Exchnge, 1987, 5, M. Pst, A. Bttistel nd F. L Mnti, Energy & Environmentl Science, 12, 5, J. Lee, S. H. Yu, C. Kim, Y. E. Sung nd J. Yoon, Physicl Chemistry Chemicl Physics, 13, 15, Z. W. Zho, X. F. Si, X. H. Liu, L. H. He nd X. X. Ling, Hydrometllurgy, 13, 133, K. T. Lee, T. N. Rmesh, F. Nn, G. Botton nd L. F. Nzr, Chemistry of Mterils, 11, 23, P. Moreu, D. Guyomrd, J. Gubicher nd F. Boucher, Chemistry of Mterils, 10, 22, B. L. Ellis nd L. F. Nzr, Current Opinion in Solid Stte & Mterils Science, 12, 16, K. Zghib, J. Trottier, P. Hovington, F. Brochu, A. Guerfi, A. Muger nd C. M. Julien, Journl of Power Sources, 11, 196, CRC Hnbook of Chemistry nd Physics, Boc Rton, CRC Press. 19. C. V. Rmn, A. Muger, F. Gendron, C. M. Julien nd K. Zghib, Journl of Power Sources, 09, 187, R. Chitrkr, H. Knoh, Y. Miyi nd K. Ooi, Industril & Engineering Chemistry Reserch, 01, 40, R. Chitrkr, Y. Mkit, K. Ooi nd A. Sonod, Chemistry Letters, 12, 41, Q. Yu, K. Sski nd T. Hirjim, Journl of Hzrdous Mterils, 13, 262, Q.-H. Zhng, S.-P. Li, S.-Y. Sun, X.-S. Yin nd J.-G. Yu, Advnced Powder Technology, 09,, A. Umeno, Y. Miyi, N. Tkgi, R. Chitrkr, K. Skne nd K. Ooi, Industril & Engineering Chemistry Reserch, 02, 41, Q.-H. Zhng, S. Sun, S. Li, H. Jing nd J.-G. Yu, Chemicl Engineering Science, 07, 62, Journl Nme, [yer], [vol], This journl is The Royl Society of Chemistry [yer]

6 Pge 5 of 5 Journl of Mterils Chemistry A 79x39mm (0 x 0 DPI)

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