review article speciation in solutions of lithium salts in

Review ArticleSpeciation in Solutions of Lithium Salts in DimethylSulfoxide Propylene Carbonate and Dimethyl Carbonate fromRaman Data A Minireview

M I Gorobets1 M B Ataev2 M M Gafurov2 and S A Kirillov1

1 Joint Department of Electrochemical Energy Systems 38A Vernadsky Ave Kyiv 03142 Ukraine2Kh I Amirkhanov Institute of Physics and Analytical Center of Common Access 94M Yaragsky St Makhachkala 367003 Russia

Correspondence should be addressed to S A Kirillov kirikievua

Received 19 August 2016 Accepted 10 October 2016

Academic Editor Christoph Krafft

Copyright copy 2016 M I Gorobets et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Our recent Raman studies of cation and anion solvation and ion pairing in solutions of lithium salts in dimethyl sulfoxide propylenecarbonate and dimethyl carbonate are briefly overviewed Special attention is paid to differences in our and existing data andconcepts As follows from our results cation solvation numbers in solutions are low (sim2) and disagree with previousmeasurementsThis discrepancy is shown to arise from correct accounting for dimerization hydrogen bonding and conformation equilibria inthe solvents disregarded in early studies Another disputable question touches upon the absence of free ions in solutions of lithiumsalts in carbonate solvents and the statement that the charge transfer in carbonate solutions is caused by SSIPs Direct proofs ofthe nature of charge carriers in the solvents studied have been obtained by means of analyses of vibrational dynamics It has beenfound that collision times for free anions are short and evidence weak interactions between anions and solvent molecules In SSIPscollision times are an order of magnitude longer thus signifying strong interactions between anions and cations In CIPs collisiontimes become shorter than in SSIPs reflecting the transformation of the structure of concentrated solutions to that of molten salts

1 Introduction

Due to its sensitivity to molecular interactions between func-tional groups of molecules and ions vibration spectroscopyis perhaps the most powerful tool for studying speciationin nonaqueous solutions This problem has been activelypursued in the past [1] and now is of great interest for non-aqueous electrolytes employed in lithium-ion batteries [2] Itis especially valuable to know the composition and structureof particles that is solvated cations solvated anions andvarious kinds of associates including solvent separated ionpairs (SSIPs) contact ion pairs (CIPs) and more complexaggregates present in solutions because their formationand reactivity are considered to determine the creation ofsolid electrolyte interfaces emerging upon chargedischargeprocesses in batteries In the case of battery electrolytesexperimentalists are deprived of opportunities to select sim-plestmodel solvents so as tomake the changes accompanyingsolvation more vivid and are forced to operate with quite

complex real systems It should be mentioned that their ownequilibria caused by hydrogen bonding isomerisation andso forth in the solvents employed in batteries are usuallypresent It makes spectroscopic studies of speciation inbattery electrolytes a formidable task

In our recent papers [3ndash7] we have described phasediagrams conductivity and Raman spectra of solutionsof six lithium salts namely lithium tetrafluoroborateLiBF4 perchlorate LiClO4 bis(oxalato) borate LiB(C2O4)2trifluoromethylsulfonate LiCF3SO3 nitrate LiNO3 andbis(trifluoromethylsulfonyl) imide LiN(CF3SO3)2 in aconcentration range from 005 to 025 mole fractions ofa salt (from diluted solutions to the mixtures of moltenLiXsdot4S solvates with LiX where X is the anion) in threesolvents dimethyl sulfoxide (CH3)2SO (DMSO) propylenecarbonate C4H6O3 (PC) and dimethyl carbonate C3H6O3(DMC) All these salts and solvents are employed inindustrial and laboratory practice Salt solutions in variousmixtures of PC and DMC and DMCrsquos fluorinated variety are

Hindawi Publishing CorporationJournal of SpectroscopyVolume 2016 Article ID 6978560 12 pageshttpdxdoiorg10115520166978560

2 Journal of Spectroscopy

readily available on themarket as the solvents for commerciallithium-ion batteries DMSO is a prospective solvent forlithium-oxygen batteries [8ndash10] Special attention has beenpaid to equilibria in the solvent studied In DMSO [11 12] andDMC [13] these include dipole-dipole interactions betweenmolecules In PC one should account for both dipole-dipoleinteractions and hydrogen bonding [14 15]

As far as speciation in DMSO solutions is concernedsignatures of cationic solvation have been characterized inprecious studies [16ndash19] and up to four DMSO moleculeshave been found to form the solvation sphere of the Li+ ioninteracting with it through the negatively charged oxygenatom of the S=O group This solvation number might becorrected since DMSO is an ordered associated liquid butdimerization equilibria have not been taken into accountin solvation studies In PC solutions solvation is visiblespectroscopically as an interaction of the Li+ ions with theoxygen atom of the C=O group [20 21] This leads to thedecomposition of dimers existing in this associated andhydrogen bonded liquid [22] The solvation number variesfrom 4 to 2 when the concentration of the solution grows[23ndash25] Spectroscopic studies of solvation in DMC whichis considered neither ordered nor hydrogen bonded haveshown that solvation of the Li+ ions strongly influencesconformation equilibria stabilizing the cis-trans conformer[26] The solvation numbers determined by spectroscopicmethods are equal to 4 [26]

Cation solvation is usually described in terms of elec-trostatic attraction whereas anion solvation is considered toarise either from electrostatic attraction between positivelycharged hydrogen atoms of the methyl groups of a solventand oxygen or fluorine atoms of an anion or from hydrogenbonding between them Anion solvation in solutions oflithium salts in DMSO manifests itself in Raman spectrain the region of stretching CH3-vibrations as an upshiftand broadening of respective lines signifying interactionsbetween anions and solvent molecules [18 19 27] In PCsolutions signatures of anion solvation are less definite [22]and spectroscopic manifestations of anion solvation in DMCsolutions have not been reported

Ion pairing in electrolyte solutions is showing up as anuprise of extra lines in the region of stretching vibrationsof anions For example upon adding LiClO4 and LiNO3 toDMSO new lines appear on the high-frequency side of thelines corresponding to the totally symmetric ]1 (A1) Cl-O and]1 (A10158401) N-O vibrations of anions For perchlorates the line

at 933 cmminus1 is assigned to free unperturbed ClO4minus anions

the line at 938-939 cmminus1 belongs to anions in SSIPs [28] andthat at 944ndash946 cmminus1 reflects the presence of CIPs whereperturbations of the anion are the strongest [29 30] Lineshifts for nitrates [16 31 32] and trifluoromethylsulfonates[17] are similarThe data on ion pairing of BF4

minus ions aremuchscarce [33 34] Bis(trifluoromethylsulfonyl) imide anion insolutions exists in the form of cis- and trans-conformers thelatter beingmore stable [35 36]Themost intense Raman lineat 740 cmminus1 corresponds to the symmetric bending 120575s (A1)CF3 vibrations and is convenient for studying ionpairing phe-nomena [37 38] For examining ion pairing phenomena in

bis(oxalato) borates the line at 724 cmminus1 corresponding to thesymmetric 120575s (A1) O-B-O bending has been recommended[39]

Signatures of ion pairing in PC are recognized in systemscontaining ClO4

minus [20 22] BF4minus [24] N(SO3CF3)2minus [40] and

CF3SO3minus [41] anions Some of this data are controversial

In particular Aroca and coworkers have shown that inLiClO4-PC solutions the line at 933 cmminus1 corresponds to freeClO4minus anions the line at 938 cmminus1 belongs to SSIPs and

that at 944 cmminus1 reflects the presence of CIPs Brooksby andFawcett disagree with this assignment considering that inNaClO4-PC solutions the line corresponding to free ClO4

minus

anions SSIPs and CIPs manifest themselves at 930 933 and938 cmminus1 respectively [22] As far as DMC solutions areconcerned free anions SSIPs CIPs and even more complexaggregates are detected in the LiAsF6-DMC system [26]

In [3ndash7] speciation in DMSO PC and DMC solutionsof lithium salts has been first described explicitly withno arbitrary assumptions in a single experiment Solvatedcations anions SSIPs and CIPs have been detected and theirconcentrations have been determined with due regard forequilibria existing in the solvents In this paper we brieflyoverview this data with special emphasis on differences inour and existing concepts Specifically we put forward anexplanation of low cation solvation numbers in solutionsand emphasize that they originate from correct accountingfor association processes in the solvents studied Secondlywe show that differences in the concentrations of CIPs insolutions of different salts can be understood in terms ofion pairs dissociation energy obtained by means of quantumchemical calculations Finally we suggest that solvationequilibria in solutions are significantly determined by thedonor numbers of solvents

2 Experimental Details

Lithium salts and solvents preliminary operations withthem their quality control and the preparation of solutionsare described in [4] Raman spectra were excited by the532 nm line of a solid state (NdYAG) laser and registeredat Analytical Center of Common Access Dagestan ScientificCenter of the Russian Academy of SciencesMakhachkala ona confocal Raman microscope (Senterra Bruker Germany)with a 20x camera lens the slit of 50 times 100mkm andresolution of 3 cmminus1 At least 20 scans were accumulated atpolarized (119868VV) and depolarized (119868VH) scattering geometrieswith the integration time of 20 s The first and the secondletters in subscripts denote the state of polarization of theincident and scattered radiation respectively V stands forvertical and H for horizontal Knowing 119868VV(]) and 119868VH(])where ] is the running wavenumber the so-called isotropicand anisotropic line profiles were calculated as

119868iso (]) = 119868VV (]) minus 43119868VH (]) 119868aniso (]) = 119868VH (])

(1)

Since all the lines studied are sharply polarized only isotropicspectra are presented in what follows

Journal of Spectroscopy 3

Solvation phenomena and ion pairing perturb themolecules of solvents and anions are showing up in Ramanspectra as appearance of new lines corresponding to vibra-tions of new structural entities These new lines are situatedin a close proximity to the lines of unperturbed particlesresulting in composite lines Their decomposition has beenperformed by amethod described in [42]where experimentalspectra are modelled by the sum of the following expressions

119868 (]) = 2119899119888 exp (12059111205912) (120591211205912)1198701 (119909)

119909 (2)

where 119909 = 1205911[412058721198882(] minus ]0)2 + 112059122 ]12 119899 = 2 if ]0 = 0 and119899 = 1 if ]0 = 0 119888 is the speed of light ]0 is the wavenumberof the line maximum 1205911 and 1205912 are certain parameters and1198701(119909) is the modified Bessel function of the second kindThis expression is more flexible than the commonly usedVoight function and is widely used for the decompositionof overlap lines [43] In order to find the dependence of theamount of particles present in solutions on the concentrationof lithium salts 119888119894 = 119891(119888salt) it was considered that 119888119894 valuesare proportional to integrated intensities of isotropic linesAs no data exist regarding scattering abilities of particlesin the free state solvation sphere SSIPs and CIPs theirpossible differences at the present state of our knowledgeweredisregarded

We skip any detailed description of the vibrational spectraof pure DMSO PC and DMC it can be found in [44ndash46] In all spectra processing procedures we account forthe presence of all lines in the investigated regions Forthe sake of simplicity in figures we give calculation resultsfor the lines directly involved in interparticle interactions(see explanations below) and do not talk over changingparameters of other lines visible in selected spectral windows

3 Results and Discussion

31 Spectroscopic Signatures of Solvation On adding lithiumsalts the Raman spectra of solvents undergo changes namelythe shift and broadening of the lines studied occur andnew lines emerge as a result of solvation RepresentativeRaman spectra reflecting cation solvation are given in Figure 1together with their fits A composite line in the region of ]10(A1015840) symmetric CSC stretch vibration can be decomposedto three component lines corresponding to the monomeric(]iso = 663ndash670 cmminus1) dimeric (]iso = 667ndash669 cmminus1) andsolvating (]iso = 674ndash676 cmminus1) DMSO molecules In thecase of PC the line corresponding to ]10 (01) breathing ringvibration can be decomposed to three component lines char-acteristic of the monomeric (]iso = 706-707 cmminus1) dimeric(]iso = 711-712 cmminus1) and solvating (]iso = 716-717 cmminus1)PC molecules In DMC solutions the line corresponding to]9 (01) OCO deformations can also be decomposed to threecomponent lines characteristic of the monomeric (]iso =513ndash515 cmminus1) dimeric (]iso = 516-517 cmminus1) and solvating(]iso = 523 cmminus1) DMC molecules

Anion solvation manifests itself in changes in Ramanspectra shown in Figure 2 Decomposition of the spectraof lithium salt solutions in DMSO in the region of ]3

(A1015840) CX stretching vibration gives two component linesConcentration dependence of their intensities reveals that thehigh-frequency component (sim2919 cmminus1) corresponds to thenonbonded DMSO molecules whereas the low-frequencyone (sim2913 cmminus1) belongs to the solvent molecules enteringthe solvation sphere of the anion and hydrogen bonded tothem

Upon adding the salt the overall PC line correspondingto ]14 (01) CH stretching vibrations is changing insignifi-cantly However the concentration dependence of data fitsreveals that on rising concentration clear redistribution ofintensity between the low- and high-frequency componentstakes place As the high-frequency component (sim2941 cmminus1)increases and the low-frequency component (sim2930 cmminus1)decreases in intensity one can be confident that the formerbelongs to the PC molecules entering the solvation sphere ofthe anion and hydrogen bonded to them whereas the latterreflects the presence of the nonbonded solvent molecules

In DMC solutions the behavior of ]2 (01) CH stretchingvibration in the salt solutions inDMC is similar to that of CH-vibration in DMSO solutions Splitting of the line occurs andin accord with concentration dependence the split lines canbe assigned to the low-frequency component (sim2919 cmminus1)corresponding to the nonbonded DMC molecules and thehigh-frequency one (sim2913 cmminus1) belonging to the solventmolecules which enter the solvation sphere of the anion andare hydrogen bonded to them

Intensity measurements enable one to find the depen-dence of the amount of particles present in solutions onthe concentration of lithium salts LiX 119888119894 = 119891(119888salt) Usingthese concentration dependencies one can calculate 119899119894 themean number of the solventmolecules bonded to cations andanions (solvation number coordination number or the so-called Bjerrum function) as

119899119894 = 119888119894119888salt (3)

where 119888119894 is the equilibrium concentration of the solventmolecules bonded to 119894th ion and 119888salt is the total concentrationof the salt It appears that for cations 119899119894 values are almostindependent on concentration being equal to ca 2 (Figure 3)This value is much less than that usually obtained in otherworksThe reason for such discrepancy lies in the fact that inprevious investigations [17 19] no equilibria in the solventsdimerization equilibrium on the first place have been takeninto account In this case Raman spectra similar to thatshown in Figure 1 are decomposed into two lines insteadof three lines in our works that is the solvent spectrumis modelled with two lines corresponding to nonsolvatingand solvating molecules Differences in fits with three andtwo lines under the envelope of a composite line have beenanalyzed in [4] Representative data are shown in Figure 4Differences between experimental and calculated intensities(Figure 4 lover panels) visually signify that the three-line fit better reflects reality Respective statistics (Table 1)support this statementThis means that disregarding possibleequilibria in solvents may lead to a significant increase in the


Iso

640 660 680 700 720 740

Iso

600 650 700 750 800

Iso

480 500 520 540

Inte

nsity

(arb

uni

ts)

Inte

nsity

(arb

uni

ts)

Inte

nsity

(arb

uni

ts)

LiClO4-DMSO t = 90∘C

Raman shift (cmminus1)

LiClO4-PC t = 25∘C LiClO4-DMC t = 25

∘C

Raman shift (cmminus1) Raman shift (cmminus1)

0

1000

2000

3000

4000

0

100

200

300

minus505

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c 0

200

400

600

Figure 1 Raman spectra of DMSO PC and DMC solutions containing 015 mole fractions of LiClO4 in regions sensitive to cation solvationeffects

Iso Iso Iso

Inte

nsity

(arb

uni

ts)

LiClO4-DMSO t = 90∘C LiClO4-PC t = 25

∘C LiClO4-DMC t = 25∘C

0

500

1000In

tens

ity (a

rb u

nits)

0

250

500

750

Inte

nsity

(arb

uni

ts)

0

2500

5000

2850 2900 2950 3000 30502800Raman shift (cmminus1)


2900 2950 3000 30502850Raman shift (cmminus1)

minus200

20

I exp

minus

I cal

c

minus300

30

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c

Figure 2 Raman spectra of DMSO PC andDMC solutions containing 015mole fractions of LiClO4 in the region sensitive to anion solvationeffects

estimated concentration of solvated ions and hence to higher(ie mistaken) solvation number values

Unlike cations the mean coordination number of anionssignificantly depends on concentration and varies withinwide limits (Figure 5)

32 Spectroscopic Signatures of Ion Pairing Signatures of ionpairing in solutions are showing up first of all as extra lines

appearing in the vicinity of intense lines corresponding tonondegenerated vibrations of anions For example addingLiBF4 to DMSO splits ]1 line of BF4

minus into three componentsat 760 763 and 768 cmminus1 which can be assigned to anions inthe free state in SSIPs and in CIPs respectively (Figure 6)Evolution of the integrated intensities of the component linesenabling one to find the concentrations of free anions and ionpairs in all solutions studied is shown in Figure 7 The datafor nitrate solutions are not presented because the spectra


DMSODMCPC

0

1

2

3

4

nLi

+

010 015 020 025005

Dim DMSO

Solv

Mon + Dim

Mon DMSO

Total DMSOLiClO4-DMSO

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)

100 095 090 085 080 075cDMSO (mole fraction)

Dim PC

Mon PCSolv

Mon + Dim

Total PCLiClO4-PC

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)

100 095 090 085 080 075cPC (mole fraction)

Dim DMC

Mon DMC

Mon + Dim

Total DMC

Solv

LiClO4-DMC

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)

100 095 090 085 080 075cDMC (mole fraction)

cLiClO4(mole fraction) cLiClO4

(mole fraction)

cLiClO4(mole fraction)cLiClO4

(mole fraction)

Figure 3 Concentration dependence of the amounts of monomeric dimeric and solvating molecules of the solvent and mean number ofthe solvent molecules bonded to cations in ionic solutions of DMSO PC and DMC

of NO3minus and the solvent overlap severely and cannot be

decomposedAs follows from the data presented in Figure 7 the

concentration of CIPs in DMSO solutions of lithium saltsdecreases in the following order of anions BF4

minus gt ClO4minus asymp

CF3SO3minus gt N(SO3CF3)2minus = B(C2O4)2minus = 0 Interestingly

dissociation energies of ion pairs Li+Aminus obtained bymeans of

quantum chemical calculations (B3LYP6-311+Glowast method)can be arranged in the same order (Table 2) This meansthat a minimal potential energy of pairwise interactionsexists (580 kJmolminus1) below which contact ion pairs inDMSO solutions of lithium salts cannot be formed and theamount of CIPs in solutions of salts in DMSO is determinedby the dissociation energy of contact ion pairs If these


Solvating DMSO

Dimeric DMSO

MonomericDMSO

Three lines

Iso

Solvating DMSO

Free DMSO

Two lines

Iso

Inte

nsity

(arb

uni

ts)

LiClO4-DMSO t = 90∘C c(LiClO4) = 015 mol

0

1000

2000

3000

4000

0

1000

2000

3000

4000

Inte

nsity

(arb

uni

ts)660 680 700 720 740640

Raman shift (cmminus1)660 680 700 720 740640


minus100

10

I exp

minus

I cal

c

minus200

20

I exp

minus

I cal

c

Figure 4 Representative example of data fits with (three lines) and without (two lines) distinguishing between monomeric and dimericmolecules of the solvent in the DMSO solution containing 015 mole fractions of LiClO4

Table 1 Computation results obtained with (three lines) andwithout (two lines) distinguishing betweenmonomeric and dimericmolecules of the solvent in the DMSO solution containing 015 molefractions of LiClO4

Parameters of fits Three lines Two lines]1 6647 66602]2 6692]3 6743 67373Best weighted sum of squares 36557 times 103 10218 times 104Weighted root mean square error 37212 62452Weighted deviation fraction 10756 times 10minus3 36318 times 10minus31198772 099998 099996

Table 2 Ion pair Li+Aminus dissociation energy obtained by means ofquantum chemical calculations [50]

Anion Ion pair dissociation energy kJmolminus1

NO3minus 653

BF4minus 602

ClO4minus 594

CF3SO3minus 594

N(SO3CF3)2minus 580B(C2O4)2minus 521

considerations are correct nitrate solutions in DMSO can besuspected to contain the maximal concentration of CIPs

In [5] significant efforts have been undertaken so asto understand the Raman spectra of solutions of LiClO4 inDMSO PC and DMC In [28ndash30] the lines at 929 932and 937 cmminus1 showing up in the LiClO4-DMSO system are

attributed to anions in free state in SSIPs and in CIPsrespectively The similar treatment of the split lines for theNaClO4-DMSO system has been made by Brooksby andFawcett [22] and that for LiClO4-H2Onanodroplets has beenmade by Guo et al [47] In the carbonate solvents data fitsclearly reveal the presence of two types of ClO4

minus-containingparticleswith the lines at ]=9325 and 937 cmminus1 in PC and at ]= 933 and 942 cmminus1 inDMCComparing this findingwith theresults obtained for DMSO solutions one may suppose thatin PC and DMC free anions are absent and only SSIPs andCIPs are showing up in Raman On the other hand Battistiand coworkers [20] preferred to assign the low-wavenumberlines to the free ClO4

minus and the high-wavenumber lines to theanions in SSIPs

In order to discern between these two assignments theconductivity data [3] appear to be helpful If one follows theassignment performed by Battisti and coworkers [20] andconsiders that the perchlorate lines at 9325 and 937 cmminus1 inPC and at 933 and 942 cmminus1 in DMC correspond to the freeanions and SSIPs respectively (Assignment 1 in Figures 7(f)and 7(g)) the order of solvents for increasing concentrationof free anions is PC lt DMSO lt DMC and that for decreasingconcentration of SSIPs is PC gt DMSO gt DMC Such ordershave nothing to do with the order of solvents for increas-ing conductivity DMC lt PC ≪ DMSO [3] If one considersthat the lines at 9325 (PC) and 933 cmminus1 (DMC) belongto SSIPs and those at 937 (PC) and 942 cmminus1 (DMC) toCIPs (Assignment 2 in Figures 7(f) and 7(g)) the presenceof free anions in PC and DMC should be excluded in thewhole concentration range studied Such consideration leadsto the order of solvents for increasing concentration of freeanions as PC = DMC(= 0) ≪ DMSO and that for decreasing


000 005 010 015 020 025

Total DMSO

Free

H-bonded

Free

H-bonded

Total PC

Anion H-bonded

Self H-bonded

LiClO4-DMSO LiClO4-PC

005 010 015 020 025000

00

02

04

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08

10

c i(m

ole f

ract

ion)

00

02

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ole f

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ion)



Free

Total DMC

H-bonded

LiClO4-DMC

00

02

04

06

08

10

c i(m

ole f

ract

ion)

005 010 015 020 025000


DMSODMCPC

010 015 020 0250050

2

4

6

cLiClO4(mole fraction)


(mole fractions)


nCl

O4minus

Figure 5 Concentration dependence of the amount of free and H-bonded molecules and mean number of the solvent molecules bonded toanions of the solvent in ionic solutions of DMSO PC and DMC

concentration of SSIPs as DMC gt PC gt DMSO which per-fectly coincide with the order of solvents for increasingconductivity It has been stressed in [5] that our conclusionis the first proof of the Fuoss theory [48] which states thatSSIPs do contribute to conductance current

The absence of solvated anions in LiClO4-PC andLiClO4-DMC systems unlike LiClO4-DMSO system cannotbe explained by the values of solvent dielectric permittivity

since DMSO and PC have a much higher dielectricpermittivity than DMC (Table 3) Probably donor numbersrule the game since the donor number of DMSO is almosttwice as much as those of PC and DMC (Table 3)

33 Spectroscopic Signatures of Ion Pairing Vibrational Dyna-mics An additional opportunity enabling one to explain


I iso

(arb

uni

ts)

LiBF4-DMSO t = 50∘C

760 770 780750Raman shift (cmminus1)

minus100

10

I exp

minus

I cal

c 0

150

300

450

Figure 6 Free anions and ion pairs in the spectrum of the totally symmetric ]1 (A1) vibration of BF4minus in the DMSO solution containing 015

mole fractions of LiBF4

Table 3 Dielectric permittivity 120576 and donor numbers DN forDMSO PC and DMC

DMSO PC DMC120576 4724 [11] 6492 [2] 3107 [2]DN 298 [16] 151 [51] 172 [51]

the absence of free ions in solutions of lithium salts incarbonate solvents and to prove the statement that the chargetransfer in carbonate solutions is caused by SSIPs is ananalysis of vibrational dynamics in the systems studied Todo so one has to use an approach based on time-correlationfunctions (TCFs) of vibrational dephasing described in detailin [42 43] TCFs 119866(119905) can be obtained by means of Fouriertransforms of Raman spectra 119868(])

119866 (119905) = int+infin

minusinfin

119868 (]) exp (2120587119894119888]119905) 119889] (4)

where 119888 is the speed of light It is usually consideredthat the main cause of line broadening in Raman is theso-called vibrational dephasing Interactions of a particlewith its environment (perturbations) lead to time-dependentchanges (modulation) of the particlersquos vibrational frequencyΔ120596 = 119891(119905) and to vibrational phase shifts If120596 is exponentiallychanging in time 119866120596(119905) = exp(minus119905120591120596) where 120591120596 is themodulation time and the TCF of vibrational dephasing canbe expressed by the Kubo equation

119866 (119905) = 11987221205912120596119890minus exp(minus119905120591120596)minus1+119905120591120596 (5)

where 1198722 = int ]2119868(])119889] int 119868(])119889] is the second vibrationalmoment (perturbation dispersion) As follows from existing

theories (for details see [42 43]) the modulation time isusually considered equal to the time between collisions inliquids 120591120596 = 120591BC Depending on perturbations TCF and thespectrum are changing If 120591120596 rarr 0 (moveable environment ofa particle weak perturbations and nonspecific interactions)TCFs are exponential and the spectra are of Lorentzianform If 120591120596 rarr infin (interactions are strong specific anddirected molecule and its environment form a rigid quasi-lattice) TCFs and the spectra become Gaussian Anotherparameter of the process is the dephasing time determinedas the integral over 119866(119905) 120591119881 = int119866(119905)119889119905

Calculations have been performed by the method sug-gested in [42 43] according to which (2) can be Fouriertransformed analytically giving 119866(119905) in the following form

119866 (119905) = exp

minus[(1199052 + 12059121)12 minus 1205911]1205912

(6)

Once 1205911 and 1205912 are known 119866(119905) can be built fit to Kuboequation (5) and analyzed In Figure 8 representative TCFsfor the free anions SSIPs and CIPs are shownTheir behavioris very characteristic It appears that dephasing times in freeanions are short In SSIPs 120591119881 become longer and respectiveTCFs ldquocoverrdquo the TCFs of free ions In CIPs 120591119881 becomeshorter and respective TCFs remain under the envelope of theTCFs of SSIPs

The analysis of modulation times appears even morestraightforward (Table 4) In free anions 120591120596 are short andevidence weak interactions between anions and their envi-ronment (solvent molecules) In SSIPs 120591120596 are an order ofmagnitude longer thus signifying strong interactions betweenanions and cations In CIPs showing up in more concen-trated solutions 120591120596 become shorter than in SSIPs probably


Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiBF4-DMSO

000

005

010

015

020

025

010 020000cLiBF4

(mole fraction)

(a)

Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiCF3SO3-DMSO

000

005

010

015

020

025

010 020000cLiCF3SO3

(mole fraction)

(b)

FreeIP

c i(m

ole f

ract

ion)

LiB(C2O4)2-DMSO

000

005

010

015

020

025

010 020000cLiB(C2O4)2

(mole fraction)

(c)

FreeIP

c i(m

ole f

ract

ion)

LiN(SO2CF3)2-DMSO

000

005

010

015

020

025

010 020000cLiN(SO2CF3)2

(mole fraction)

(d)

FreeSSIPCP

c i(m

ole f

ract

ion)

LiClO4-DMSO

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(e)

Assignment 1Free1st IP

Assignment 2FreeSSIPCP

c i(m

ole f

ract

ion)

LiClO4-PC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(f)



c i(m

ole f

ract

ion)

LiClO4-DMC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(g)

Figure 7 Concentrations of free anions and ion pairs in solutions of DMSO PC and DMC

demonstrating that the structure of concentrated solutionsacquires the features of molten salts for which short 120591120596 arequite obvious [49] This proves our conjectures regardingthe nature of charge carriers in carbonate solvents A moredetailed description of these results will be given in ourforthcoming papers

4 Conclusion

In this paper a brief overview of our Raman studies of cationand anion solvation and ion pairing in DMSO PC andDMC solutions of lithium salts namely tetrafluoroborateperchlorate nitrate bis(oxalato) borate trifluoromethylsul-fonate and bis(trifluoromethylsulfonyl) imide is presentedSpecial attention is paid to differences in our and existingdata and concepts As indicated from our data low cationsolvation numbers (sim2) in solutions disagree with previous

measurements This discrepancy is shown to arise fromcorrect accounting for possible equilibria in the solventsstudied like dimerization (DMSO and PC) hydrogen bond-ing (PC) and conformation equilibria (DMC) disregardedin early studies This unforeseen result has some analogiesin molecular dynamics simulations of ionic solvation andprobably calls for a reconsideration of existing data onsolvation numbers Another disputable question touchesupon the absence of free ions in solutions of lithium salts incarbonate solvents and the statement that the charge transferin carbonate solutions is caused by SSIPs In order to supportthis conclusion donor numbers have been analyzed whichin PC and DMC are as twice as high as those in DMSOThis means that solvation effects prevail in DMSO whereasin PC and DMC ion pairing is being brought to the foreFurthermore differences in the concentrations of CIPs insolutions of different salts can be understood in terms of


Table 4 Relaxation 120591119881 and modulation 120591120596 times for Cl-O vibrations of ClO4minus anion in ionic solutions of DMSO PC and DMC

c mf LiClO4-DMSO LiClO4-DMC LiClO4-PC120591119881 ps 120591120596 ps 120591119881 ps 120591120596 ps 120591119881 ps 120591120596 ps

Free anion005 2171 0710b01 2101 0782b015 1901 0463b02 1641 0249b025 1411 0162b

Anion in SSIP005 3911 925b 14 plusmn 02 9 plusmn 1 27 plusmn 03 53 plusmn 0301 3931 189b 13 plusmn 02 9 plusmn 1 28 plusmn 04 72 plusmn 04015 3531 108b 13 plusmn 02 8 plusmn 1 29 plusmn 04 79 plusmn 0402 3171 996b 12 plusmn 02 6 plusmn 1 28 plusmn 05 97 plusmn 05025 3081 109b 11 plusmn 02 6 plusmn 1 28 plusmn 05 100 plusmn 05

Anion in CIP00501 30 plusmn 03 21 plusmn 03 10 plusmn 02 20 plusmn 02 076 plusmn 004 017 plusmn 004015 24 plusmn 01 73 plusmn 06 09 plusmn 01 08 plusmn 01 086 plusmn 003 023 plusmn 00502 175 plusmn 002 064 plusmn 009 09 plusmn 01 04 plusmn 01 084 plusmn 003 013 plusmn 003025 137 plusmn 002 025 plusmn 004 10 plusmn 01 035 plusmn 005 082 plusmn 003 013 plusmn 0031Less than 1 uncertainty bLess than 2 uncertainty

Free anionsSSIPCIP

2 4 6 8 100t (ps)

00

05

10

GV(t)

Figure 8 Representative time-correlation functions of dephasingof ClO4

minus anion in free state SSIP and CIP in the DMSO solutioncontaining 01 mole fractions of LiClO4

ion pair dissociation energies obtained by means of quantumchemical calculations Even more direct proofs of the natureof charge carriers in carbonate solvents have been obtainedby means of analyses of vibrational dynamics It has been

found that modulation (collision) times for free anions areshort and evidence weak interactions between anions andsolvent molecules In SSIPs 120591120596 are an order of magnitudelonger thus signifying strong interactions between anions andcations In CIPs 120591120596 become shorter than in SSIPs reflectingthe transformation of the structure of concentrated solutionsto that of molten salts

Competing Interests

The authors declare no conflict of interests

Acknowledgments

M B Ataev and M M Gafurov were supported by theRussian Federation Basic Research Fund (Grant no 13-03-00384A) and the Ministry of Education and Science of theRussian Federation (State Contract no 16552117092)

References

[1] J M Alıa ldquoRaman spectroscopic studies of ion-ion interactionsin aqueous and nonaqueous electrolyte solutionsrdquo inHandbookof Raman Spectroscopy From the Research Laboratory to theProcess Line I R Lewis and H G M Edward Eds pp 617ndash683 Marcel Dekker New York NY USA 2001

[2] K Xu ldquoNonaqueous liquid electrolytes for lithium-basedrechargeable batteriesrdquo Chemical Reviews vol 104 no 10 pp4303ndash4417 2004

[3] S A Kirillov M I Gorobets D O Tretyakov M B Ataev andM M Gafurov ldquoPhase diagrams and conductivity of lithiumsalt systems in dimethyl sulfoxide propylene carbonate and


dimethyl carbonaterdquo Journal of Molecular Liquids vol 205 pp78ndash84 2015

[4] M I Gorobets M B Ataev M M Gafurov and S AKirillov ldquoRaman study of solvation in solutions of lithiumsalts in dimethyl sulfoxide propylene carbonate and dimethylcarbonaterdquo Journal of Molecular Liquids vol 205 pp 98ndash1092015

[5] S A Kirillov M M Gafurov M I Gorobets and M BAtaev ldquoRaman study of ion pairing in solutions of lithiumsalts in dimethyl sulfoxide propylene carbonate and dimethylcarbonaterdquo Journal of Molecular Liquids vol 199 pp 167ndash1742014

[6] M M Gafurov S A Kirillov M I Gorobets et al ldquoPhaseequilibria and ionic solvation in the lithium tetrafluoroboratendashdimethylsulfoxide systemrdquo Journal of Applied Spectroscopy vol81 no 6 pp 912ndash918 2015

[7] MMGafurovM B Ataev K S Rabadanov et al ldquoSolvation ofLiBF4 ions in dimethyl sulfoxide solutions according to Ramanspectroscopy datardquoRussian Journal of Physical Chemistry A vol89 no 4 pp 639ndash643 2015

[8] M Balaish A Kraytsberg and Y Ein-Eli ldquoA critical review onlithium-air battery electrolytesrdquo Physical Chemistry ChemicalPhysics vol 16 no 7 pp 2801ndash2822 2014

[9] M J Trahan SMukerjee E J PlichtMAHendrickson andKMAbraham ldquoStudies of li-air cells utilizing dimethyl sulfoxide-based electrolyterdquo Journal of the Electrochemical Society vol160 no 2 pp A259ndashA267 2013

[10] Q Yu and S Ye ldquoIn situ study of oxygen reduction in dimethylsulfoxide (DMSO) solution a fundamental study for develop-ment of the lithium-oxygen batteryrdquo The Journal of PhysicalChemistry C vol 119 no 22 pp 12236ndash12250 2015

[11] S A Kirillov M I Gorobets M M Gafurov M B Ataev andK S Rabadanov ldquoSelf-association and picosecond dynamics inliquid dimethyl sulfoxiderdquo Journal of Physical Chemistry B vol117 no 32 pp 9439ndash9448 2013

[12] S A Kirillov M I Gorobets M M Gafurov K S Rabadanovand M B Ataev ldquoTemperature dependence of associativeequilibria of DMSO according to Raman scattering spectrardquoRussian Journal of Physical Chemistry A vol 88 no 1 pp 175ndash177 2014

[13] L Gontrani O Russina F C Marincola and R CaminitildquoAn energy dispersive x-ray scattering and molecular dynamicsstudy of liquid dimethyl carbonaterdquo Journal of Chemical Physicsvol 131 no 24 Article ID 244503 2009

[14] A Brodin and P Jacobsson ldquoDipolar interaction andmolecularordering in liquid propylene carbonate anomalous dielectricsusceptibility and Raman non-coincidence effectrdquo Journal ofMolecular Liquids vol 164 no 1-2 pp 17ndash21 2011

[15] Y Wang and P B Balbuena ldquoAssociations of alkyl carbon-ates intermolecular C-Hsdot sdot sdotO interactionsrdquo Journal of PhysicalChemistry A vol 105 no 43 pp 9972ndash9982 2001

[16] A A Kloss and W R Fawcett ldquoATR-FTIR studies of ionicsolvation and ion-pairing in dimethyl sulfoxide solutions of thealkali metal nitratesrdquo Journal of the Chemical Society FaradayTransactions vol 94 no 11 pp 1587ndash1591 1998

[17] J M Alıa and H G M Edwards ldquoIon solvation and ionassociation in lithium trifluoromethanesulfonate solutions inthree aprotic solvents An FT-Raman spectroscopic studyrdquoVibrational Spectroscopy vol 24 no 2 pp 185ndash200 2000

[18] Z Wang B Huang S Wang R Xue X Huang and L ChenldquoVibrational spectroscopic study of the interaction between

lithium perchlorate and dimethylsulfoxiderdquo ElectrochimicaActa vol 42 no 17 pp 2611ndash2617 1997

[19] X Xuan J Wang Y Zhao and J Zhu ldquoExperimental and com-putational studies on the solvation of lithium tetrafluorobrate indimethyl sulfoxiderdquo Journal of Raman Spectroscopy vol 38 no7 pp 865ndash872 2007

[20] D Battisti G A Nazri B Klassen and R Aroca ldquoVibrationalstudies of lithiumperchlorate in propylene carbonate solutionsrdquoJournal of Physical Chemistry vol 97 no 22 pp 5826ndash58301993

[21] T Li and P B Balbuena ldquoTheoretical studies of lithiumperchlorate in ethylene carbonate propylene carbonate andtheir mixturesrdquo Journal of the Electrochemical Society vol 146no 10 pp 3613ndash3622 1999

[22] P A Brooksby and W R Fawcett ldquoInfrared (attenuated totalreflection) study of propylene carbonate solutions containinglithium and sodium perchloraterdquo Spectrochimica Acta Part AMolecular and Biomolecular Spectroscopy vol 64 no 2 pp 372ndash382 2006

[23] X Xuan J Wang J Tang G Qu and J Lu ldquoA vibra-tional spectroscopic study of ion solvation in lithium perchlo-ratepropylene carbonate electrolyterdquo Physics and Chemistry ofLiquids vol 39 no 3 pp 327ndash342 2001

[24] H Tsunekawa A Narumi M Sano A Hiwara M Fujita andH Yokoyama ldquoSolvation and ion association studies of LiBF4-propylenecarbonate and LiBF4-propylenecarbonate-trimethylphosphate solutionsrdquo Journal of Physical Chemistry B vol 107no 39 pp 10962ndash10966 2003

[25] K Kondo M Sano A Hiwara et al ldquoConductivity andsolvation of Li+ ions of LiPF6 in propylene carbonate solutionsrdquoJournal of Physical Chemistry B vol 104 no 20 pp 5040ndash50442000

[26] L Doucey M Revault A Lautie A Chausse and R MessinaldquoA study of the LiLi+ couple in DMC and PC solvents Part1 characterization of LiAsF6DMC and LiAsF6PC solutionsrdquoElectrochimica Acta vol 44 no 14 pp 2371ndash2377 1999

[27] K Wakabayashi Y Maeda K Ozutsumi and H OhtakildquoThe structure of solvated halide ions in dimethyl sulfoxidestudied by Raman spectroscopy and X-ray diffractionrdquo Journalof Molecular Liquids vol 110 no 1ndash3 pp 43ndash50 2004

[28] M I S Sastry and S Singh ldquoRaman spectral studies of solutionsof alkali metal perchlorates in dimethyl sulfoxide and waterrdquoCanadian Journal of Chemistry vol 63 no 7 pp 1351ndash1356 1985

[29] M Chabanel D Legoff and K Touaj ldquoAggregation of perchlo-rates in aprotic donor solvents Part 1mdashlithium and sodium per-chloratesrdquo Journal of theChemical Society FaradayTransactionsvol 92 pp 4199ndash4205 1996

[30] I S Perelygin and G P Mikhailov ldquoAppearance of ion-ioninteractions in the Raman scattering spectra of the perchlorateionrdquo Journal of Applied Spectroscopy vol 49 no 1 pp 713ndash7171988

[31] R Wooldridge M Fisher G Ritzhaupt and J P DevlinldquoDependence of ion pairing and solvation on solution tem-perature evidence from DMSO solution and matrix-solvationspectrardquoThe Journal of Chemical Physics vol 86 no 8 pp 4391ndash4395 1987

[32] I S Perelygin and G P Mikhailov ldquoManifestations of ion-ioninteractions in the Raman spectra of the nitrate ionrdquo Journal ofApplied Spectroscopy vol 48 no 5 pp 516ndash521 1988

[33] J M Alia and H G M Edwards ldquoFT-Raman study of ionicinteractions in lithium and silver tetrafluoroborate solutions in


acrylonitrilerdquo Journal of Solution Chemistry vol 29 no 9 pp781ndash797 2000

[34] I S Perelygin and M A Klimchuk ldquoManifestations of interi-onic interactions in the IR absorption spectra of the tetrafluo-roborate ionrdquo Journal of Applied Spectroscopy vol 50 no 2 pp207ndash211 1989

[35] P Johansson S P Gejji J Tegenfeldt and J Lindgren ldquoTheimide ion potential energy surface and geometriesrdquo Elec-trochimica Acta vol 43 no 10-11 pp 1375ndash1379 1998

[36] M Herstedt M Smirnov P Johansson et al ldquoSpectro-scopic characterization of the conformational states of thebis(trifluoromethanesulfonyl)imide anion (TFSIminus)rdquo Journal ofRaman Spectroscopy vol 36 no 8 pp 762ndash770 2005

[37] I Rey P Johansson J Lindgren J C Lassegues J Grondinand L Servant ldquoSpectroscopic and theoretical study of(CF3SO2)2N

minus (TFSIminus) and (CF3SO2)2NH(HTFSI)rdquoThe Journalof Physical Chemistry A vol 102 no 19 pp 3249ndash3258 1998

[38] S P Gejji C H Suresh K Babu and S R Gadre ldquoAb initiostructure and vibrational frequencies of (CF3SO2)2N

minusLi+ ionpairsrdquo Journal of Physical Chemistry A vol 103 no 37 pp 7474ndash7480 1999

[39] R Holomb W Xu H Markusson P Johansson and P Jacobs-son ldquoVibrational spectroscopy and ab initio studies of lithiumbis(oxalato)borate (LiBOB) in different solventsrdquo Journal ofPhysical Chemistry A vol 110 no 40 pp 11467ndash11472 2006

[40] Z Wang W Gao X Huang Y Mo and L Chen ldquoSpectro-scopic studies on interactions andmicrostructures in propylenecarbonate-LiTFSI electrolytesrdquo Journal of Raman Spectroscopyvol 32 no 11 pp 900ndash905 2001

[41] I S Perelygin and M A Klimchuk ldquoManifestations of interi-onic interactions in IR spectra of the trifluoromethanesulfonateionrdquo Journal of Applied Spectroscopy vol 55 no 3 pp 855ndash8591991

[42] S AKirillov ldquoNovel approaches in spectroscopy of interparticleinteractions vibrational line profiles and anomalous non-coincidence effectsrdquo in Novel Approaches to the Structure andDynamics of Liquids Experiments Theories and SimulationsJ Samios and V Durov Eds NATO ASI Series pp 193ndash227Kluwer Dordrecht Netherland 2004

[43] S AKirillov ldquoSpectroscopy of interparticle interactions in ionicand molecular liquids novel approachesrdquo Pure and AppliedChemistry vol 76 no 1 pp 171ndash181 2004

[44] M-T Forel and M Tranquille ldquoSpectres de vibration dudimethylsulfoxyde et dn dimethylsulfoxyde-d6rdquo SpectrochimicaActa Part A Molecular Spectroscopy vol 26 no 5 pp 1023ndash1034 1970

[45] G J Janz J Ambrose JW Coutts and J R Downey Jr ldquoRamanspectrum of propylene carbonaterdquo Spectrochimica Acta Part AMolecular Spectroscopy vol 35 no 2 pp 175ndash179 1979

[46] J E Katon andMD Cohen ldquoThe vibrational spectra and struc-ture of dimethyl carbonate and its conformational behaviorrdquoCanadian Journal of Chemistry vol 53 no 9 pp 1378ndash13861975

[47] X Guo S H Tan S F Pang and Y H Zhang ldquoMeasurementof the association constants through micro-Raman spectraof supersaturated lithium perchlorate dropletsrdquo Science ChinaChemistry vol 56 no 11 pp 1633ndash1640 2013

[48] R M Fuoss ldquoConductance-concentration function for thepaired ion modelrdquo Journal of Physical Chemistry vol 82 no 22pp 2427ndash2440 1978

[49] S A Kirillov ldquoInteractions and picosecond dynamics inmoltensalts a rewiew with comparison to molecular liquidsrdquo Journalof Molecular Liquids vol 76 no 1-2 pp 35ndash95 1998

[50] E Jonsson and P Johansson ldquoModern battery electrolytes ion-ion interactions in Li+Na+ conductors fromDFT calculationsrdquoPhysical Chemistry Chemical Physics vol 14 no 30 pp 10774ndash10779 2012

[51] M Takeuchi N Matubayasi Y Kameda B Minofar S-I Ishig-uro and Y Umebayashi ldquoFree-energy and structural analysisof ion solvation and contact ion-pair formation of Li+ with BFminus4and PFminus6 in water and carbonate solventsrdquo Journal of PhysicalChemistry B vol 116 no 22 pp 6476ndash6487 2012

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


readily available on themarket as the solvents for commerciallithium-ion batteries DMSO is a prospective solvent forlithium-oxygen batteries [8ndash10] Special attention has beenpaid to equilibria in the solvent studied In DMSO [11 12] andDMC [13] these include dipole-dipole interactions betweenmolecules In PC one should account for both dipole-dipoleinteractions and hydrogen bonding [14 15]

As far as speciation in DMSO solutions is concernedsignatures of cationic solvation have been characterized inprecious studies [16ndash19] and up to four DMSO moleculeshave been found to form the solvation sphere of the Li+ ioninteracting with it through the negatively charged oxygenatom of the S=O group This solvation number might becorrected since DMSO is an ordered associated liquid butdimerization equilibria have not been taken into accountin solvation studies In PC solutions solvation is visiblespectroscopically as an interaction of the Li+ ions with theoxygen atom of the C=O group [20 21] This leads to thedecomposition of dimers existing in this associated andhydrogen bonded liquid [22] The solvation number variesfrom 4 to 2 when the concentration of the solution grows[23ndash25] Spectroscopic studies of solvation in DMC whichis considered neither ordered nor hydrogen bonded haveshown that solvation of the Li+ ions strongly influencesconformation equilibria stabilizing the cis-trans conformer[26] The solvation numbers determined by spectroscopicmethods are equal to 4 [26]

Cation solvation is usually described in terms of elec-trostatic attraction whereas anion solvation is considered toarise either from electrostatic attraction between positivelycharged hydrogen atoms of the methyl groups of a solventand oxygen or fluorine atoms of an anion or from hydrogenbonding between them Anion solvation in solutions oflithium salts in DMSO manifests itself in Raman spectrain the region of stretching CH3-vibrations as an upshiftand broadening of respective lines signifying interactionsbetween anions and solvent molecules [18 19 27] In PCsolutions signatures of anion solvation are less definite [22]and spectroscopic manifestations of anion solvation in DMCsolutions have not been reported

Ion pairing in electrolyte solutions is showing up as anuprise of extra lines in the region of stretching vibrationsof anions For example upon adding LiClO4 and LiNO3 toDMSO new lines appear on the high-frequency side of thelines corresponding to the totally symmetric ]1 (A1) Cl-O and]1 (A10158401) N-O vibrations of anions For perchlorates the line

at 933 cmminus1 is assigned to free unperturbed ClO4minus anions

the line at 938-939 cmminus1 belongs to anions in SSIPs [28] andthat at 944ndash946 cmminus1 reflects the presence of CIPs whereperturbations of the anion are the strongest [29 30] Lineshifts for nitrates [16 31 32] and trifluoromethylsulfonates[17] are similarThe data on ion pairing of BF4

minus ions aremuchscarce [33 34] Bis(trifluoromethylsulfonyl) imide anion insolutions exists in the form of cis- and trans-conformers thelatter beingmore stable [35 36]Themost intense Raman lineat 740 cmminus1 corresponds to the symmetric bending 120575s (A1)CF3 vibrations and is convenient for studying ionpairing phe-nomena [37 38] For examining ion pairing phenomena in

bis(oxalato) borates the line at 724 cmminus1 corresponding to thesymmetric 120575s (A1) O-B-O bending has been recommended[39]

Signatures of ion pairing in PC are recognized in systemscontaining ClO4

minus [20 22] BF4minus [24] N(SO3CF3)2minus [40] and

CF3SO3minus [41] anions Some of this data are controversial

In particular Aroca and coworkers have shown that inLiClO4-PC solutions the line at 933 cmminus1 corresponds to freeClO4minus anions the line at 938 cmminus1 belongs to SSIPs and

that at 944 cmminus1 reflects the presence of CIPs Brooksby andFawcett disagree with this assignment considering that inNaClO4-PC solutions the line corresponding to free ClO4

minus

anions SSIPs and CIPs manifest themselves at 930 933 and938 cmminus1 respectively [22] As far as DMC solutions areconcerned free anions SSIPs CIPs and even more complexaggregates are detected in the LiAsF6-DMC system [26]

In [3ndash7] speciation in DMSO PC and DMC solutionsof lithium salts has been first described explicitly withno arbitrary assumptions in a single experiment Solvatedcations anions SSIPs and CIPs have been detected and theirconcentrations have been determined with due regard forequilibria existing in the solvents In this paper we brieflyoverview this data with special emphasis on differences inour and existing concepts Specifically we put forward anexplanation of low cation solvation numbers in solutionsand emphasize that they originate from correct accountingfor association processes in the solvents studied Secondlywe show that differences in the concentrations of CIPs insolutions of different salts can be understood in terms ofion pairs dissociation energy obtained by means of quantumchemical calculations Finally we suggest that solvationequilibria in solutions are significantly determined by thedonor numbers of solvents

2 Experimental Details

Lithium salts and solvents preliminary operations withthem their quality control and the preparation of solutionsare described in [4] Raman spectra were excited by the532 nm line of a solid state (NdYAG) laser and registeredat Analytical Center of Common Access Dagestan ScientificCenter of the Russian Academy of SciencesMakhachkala ona confocal Raman microscope (Senterra Bruker Germany)with a 20x camera lens the slit of 50 times 100mkm andresolution of 3 cmminus1 At least 20 scans were accumulated atpolarized (119868VV) and depolarized (119868VH) scattering geometrieswith the integration time of 20 s The first and the secondletters in subscripts denote the state of polarization of theincident and scattered radiation respectively V stands forvertical and H for horizontal Knowing 119868VV(]) and 119868VH(])where ] is the running wavenumber the so-called isotropicand anisotropic line profiles were calculated as

119868iso (]) = 119868VV (]) minus 43119868VH (]) 119868aniso (]) = 119868VH (])

(1)

Since all the lines studied are sharply polarized only isotropicspectra are presented in what follows



119868 (]) = 2119899119888 exp (12059111205912) (120591211205912)1198701 (119909)

119909 (2)










119899119894 = 119888119894119888salt (3)



Iso

640 660 680 700 720 740

Iso

600 650 700 750 800

Iso

480 500 520 540

Inte

nsity

(arb

uni

ts)

Inte

nsity

(arb

uni

ts)

Inte

nsity

(arb

uni

ts)




∘C


0

1000

2000

3000

4000

0

100

200

300

minus505

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c 0

200

400

600


Iso Iso Iso

Inte

nsity

(arb

uni

ts)



0

500

1000In

tens

ity (a

rb u

nits)

0

250

500

750

Inte

nsity

(arb

uni

ts)

0

2500

5000




minus200

20

I exp

minus

I cal

c

minus300

30

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c








DMSODMCPC

0

1

2

3

4

nLi

+

010 015 020 025005

Dim DMSO

Solv

Mon + Dim

Mon DMSO


005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)


Dim PC

Mon PCSolv

Mon + Dim

Total PCLiClO4-PC

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)


Dim DMC

Mon DMC

Mon + Dim

Total DMC

Solv

LiClO4-DMC

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)



(mole fraction)


(mole fraction)










Solvating DMSO

Dimeric DMSO

MonomericDMSO

Three lines

Iso

Solvating DMSO

Free DMSO

Two lines

Iso

Inte

nsity

(arb

uni

ts)


0

1000

2000

3000

4000

0

1000

2000

3000

4000

Inte

nsity

(arb

uni

ts)660 680 700 720 740640



minus100

10

I exp

minus

I cal

c

minus200

20

I exp

minus

I cal

c






NO3minus 653

BF4minus 602

ClO4minus 594

CF3SO3minus 594









000 005 010 015 020 025

Total DMSO

Free

H-bonded

Free

H-bonded

Total PC

Anion H-bonded

Self H-bonded


005 010 015 020 025000

00

02

04

06

08

10

c i(m

ole f

ract

ion)

00

02

04

06

08

10

c i(m

ole f

ract

ion)



Free

Total DMC

H-bonded

LiClO4-DMC

00

02

04

06

08

10

c i(m

ole f

ract

ion)

005 010 015 020 025000


DMSODMCPC

010 015 020 0250050

2

4

6



(mole fractions)


nCl

O4minus







I iso

(arb

uni

ts)



minus100

10

I exp

minus

I cal

c 0

150

300

450




DMSO PC DMC120576 4724 [11] 6492 [2] 3107 [2]DN 298 [16] 151 [51] 172 [51]


119866 (119905) = int+infin

minusinfin

119868 (]) exp (2120587119894119888]119905) 119889] (4)






119866 (119905) = exp

minus[(1199052 + 12059121)12 minus 1205911]1205912

(6)




Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiBF4-DMSO

000

005

010

015

020

025

010 020000cLiBF4

(mole fraction)

(a)

Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiCF3SO3-DMSO

000

005

010

015

020

025

010 020000cLiCF3SO3

(mole fraction)

(b)

FreeIP

c i(m

ole f

ract

ion)

LiB(C2O4)2-DMSO

000

005

010

015

020

025

010 020000cLiB(C2O4)2

(mole fraction)

(c)

FreeIP

c i(m

ole f

ract

ion)

LiN(SO2CF3)2-DMSO

000

005

010

015

020

025

010 020000cLiN(SO2CF3)2

(mole fraction)

(d)

FreeSSIPCP

c i(m

ole f

ract

ion)

LiClO4-DMSO

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(e)



c i(m

ole f

ract

ion)

LiClO4-PC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(f)



c i(m

ole f

ract

ion)

LiClO4-DMC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(g)



4 Conclusion






Free anion005 2171 0710b01 2101 0782b015 1901 0463b02 1641 0249b025 1411 0162b



Free anionsSSIPCIP

2 4 6 8 100t (ps)

00

05

10

GV(t)





Competing Interests


Acknowledgments


References




































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



119868 (]) = 2119899119888 exp (12059111205912) (120591211205912)1198701 (119909)

119909 (2)










119899119894 = 119888119894119888salt (3)



Iso

640 660 680 700 720 740

Iso

600 650 700 750 800

Iso

480 500 520 540

Inte

nsity

(arb

uni

ts)

Inte

nsity

(arb

uni

ts)

Inte

nsity

(arb

uni

ts)




∘C


0

1000

2000

3000

4000

0

100

200

300

minus505

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c 0

200

400

600


Iso Iso Iso

Inte

nsity

(arb

uni

ts)



0

500

1000In

tens

ity (a

rb u

nits)

0

250

500

750

Inte

nsity

(arb

uni

ts)

0

2500

5000




minus200

20

I exp

minus

I cal

c

minus300

30

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c








DMSODMCPC

0

1

2

3

4

nLi

+

010 015 020 025005

Dim DMSO

Solv

Mon + Dim

Mon DMSO


005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)


Dim PC

Mon PCSolv

Mon + Dim

Total PCLiClO4-PC

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)


Dim DMC

Mon DMC

Mon + Dim

Total DMC

Solv

LiClO4-DMC

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)



(mole fraction)


(mole fraction)










Solvating DMSO

Dimeric DMSO

MonomericDMSO

Three lines

Iso

Solvating DMSO

Free DMSO

Two lines

Iso

Inte

nsity

(arb

uni

ts)


0

1000

2000

3000

4000

0

1000

2000

3000

4000

Inte

nsity

(arb

uni

ts)660 680 700 720 740640



minus100

10

I exp

minus

I cal

c

minus200

20

I exp

minus

I cal

c






NO3minus 653

BF4minus 602

ClO4minus 594

CF3SO3minus 594









000 005 010 015 020 025

Total DMSO

Free

H-bonded

Free

H-bonded

Total PC

Anion H-bonded

Self H-bonded


005 010 015 020 025000

00

02

04

06

08

10

c i(m

ole f

ract

ion)

00

02

04

06

08

10

c i(m

ole f

ract

ion)



Free

Total DMC

H-bonded

LiClO4-DMC

00

02

04

06

08

10

c i(m

ole f

ract

ion)

005 010 015 020 025000


DMSODMCPC

010 015 020 0250050

2

4

6



(mole fractions)


nCl

O4minus







I iso

(arb

uni

ts)



minus100

10

I exp

minus

I cal

c 0

150

300

450




DMSO PC DMC120576 4724 [11] 6492 [2] 3107 [2]DN 298 [16] 151 [51] 172 [51]


119866 (119905) = int+infin

minusinfin

119868 (]) exp (2120587119894119888]119905) 119889] (4)






119866 (119905) = exp

minus[(1199052 + 12059121)12 minus 1205911]1205912

(6)




Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiBF4-DMSO

000

005

010

015

020

025

010 020000cLiBF4

(mole fraction)

(a)

Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiCF3SO3-DMSO

000

005

010

015

020

025

010 020000cLiCF3SO3

(mole fraction)

(b)

FreeIP

c i(m

ole f

ract

ion)

LiB(C2O4)2-DMSO

000

005

010

015

020

025

010 020000cLiB(C2O4)2

(mole fraction)

(c)

FreeIP

c i(m

ole f

ract

ion)

LiN(SO2CF3)2-DMSO

000

005

010

015

020

025

010 020000cLiN(SO2CF3)2

(mole fraction)

(d)

FreeSSIPCP

c i(m

ole f

ract

ion)

LiClO4-DMSO

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(e)



c i(m

ole f

ract

ion)

LiClO4-PC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(f)



c i(m

ole f

ract

ion)

LiClO4-DMC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(g)



4 Conclusion






Free anion005 2171 0710b01 2101 0782b015 1901 0463b02 1641 0249b025 1411 0162b



Free anionsSSIPCIP

2 4 6 8 100t (ps)

00

05

10

GV(t)





Competing Interests


Acknowledgments


References




































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Iso

640 660 680 700 720 740

Iso

600 650 700 750 800

Iso

480 500 520 540

Inte

nsity

(arb

uni

ts)

Inte

nsity

(arb

uni

ts)

Inte

nsity

(arb

uni

ts)




∘C


0

1000

2000

3000

4000

0

100

200

300

minus505

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c 0

200

400

600


Iso Iso Iso

Inte

nsity

(arb

uni

ts)



0

500

1000In

tens

ity (a

rb u

nits)

0

250

500

750

Inte

nsity

(arb

uni

ts)

0

2500

5000




minus200

20

I exp

minus

I cal

c

minus300

30

I exp

minus

I cal

c

minus100

10

I exp

minus

I cal

c








DMSODMCPC

0

1

2

3

4

nLi

+

010 015 020 025005

Dim DMSO

Solv

Mon + Dim

Mon DMSO


005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)


Dim PC

Mon PCSolv

Mon + Dim

Total PCLiClO4-PC

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)


Dim DMC

Mon DMC

Mon + Dim

Total DMC

Solv

LiClO4-DMC

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)



(mole fraction)


(mole fraction)










Solvating DMSO

Dimeric DMSO

MonomericDMSO

Three lines

Iso

Solvating DMSO

Free DMSO

Two lines

Iso

Inte

nsity

(arb

uni

ts)


0

1000

2000

3000

4000

0

1000

2000

3000

4000

Inte

nsity

(arb

uni

ts)660 680 700 720 740640



minus100

10

I exp

minus

I cal

c

minus200

20

I exp

minus

I cal

c






NO3minus 653

BF4minus 602

ClO4minus 594

CF3SO3minus 594









000 005 010 015 020 025

Total DMSO

Free

H-bonded

Free

H-bonded

Total PC

Anion H-bonded

Self H-bonded


005 010 015 020 025000

00

02

04

06

08

10

c i(m

ole f

ract

ion)

00

02

04

06

08

10

c i(m

ole f

ract

ion)



Free

Total DMC

H-bonded

LiClO4-DMC

00

02

04

06

08

10

c i(m

ole f

ract

ion)

005 010 015 020 025000


DMSODMCPC

010 015 020 0250050

2

4

6



(mole fractions)


nCl

O4minus







I iso

(arb

uni

ts)



minus100

10

I exp

minus

I cal

c 0

150

300

450




DMSO PC DMC120576 4724 [11] 6492 [2] 3107 [2]DN 298 [16] 151 [51] 172 [51]


119866 (119905) = int+infin

minusinfin

119868 (]) exp (2120587119894119888]119905) 119889] (4)






119866 (119905) = exp

minus[(1199052 + 12059121)12 minus 1205911]1205912

(6)




Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiBF4-DMSO

000

005

010

015

020

025

010 020000cLiBF4

(mole fraction)

(a)

Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiCF3SO3-DMSO

000

005

010

015

020

025

010 020000cLiCF3SO3

(mole fraction)

(b)

FreeIP

c i(m

ole f

ract

ion)

LiB(C2O4)2-DMSO

000

005

010

015

020

025

010 020000cLiB(C2O4)2

(mole fraction)

(c)

FreeIP

c i(m

ole f

ract

ion)

LiN(SO2CF3)2-DMSO

000

005

010

015

020

025

010 020000cLiN(SO2CF3)2

(mole fraction)

(d)

FreeSSIPCP

c i(m

ole f

ract

ion)

LiClO4-DMSO

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(e)



c i(m

ole f

ract

ion)

LiClO4-PC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(f)



c i(m

ole f

ract

ion)

LiClO4-DMC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(g)



4 Conclusion






Free anion005 2171 0710b01 2101 0782b015 1901 0463b02 1641 0249b025 1411 0162b



Free anionsSSIPCIP

2 4 6 8 100t (ps)

00

05

10

GV(t)





Competing Interests


Acknowledgments


References




































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


DMSODMCPC

0

1

2

3

4

nLi

+

010 015 020 025005

Dim DMSO

Solv

Mon + Dim

Mon DMSO


005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)


Dim PC

Mon PCSolv

Mon + Dim

Total PCLiClO4-PC

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)


Dim DMC

Mon DMC

Mon + Dim

Total DMC

Solv

LiClO4-DMC

005 010 015 020 02500000

02

04

06

08

10

c i(m

ole f

ract

ion)



(mole fraction)


(mole fraction)










Solvating DMSO

Dimeric DMSO

MonomericDMSO

Three lines

Iso

Solvating DMSO

Free DMSO

Two lines

Iso

Inte

nsity

(arb

uni

ts)


0

1000

2000

3000

4000

0

1000

2000

3000

4000

Inte

nsity

(arb

uni

ts)660 680 700 720 740640



minus100

10

I exp

minus

I cal

c

minus200

20

I exp

minus

I cal

c






NO3minus 653

BF4minus 602

ClO4minus 594

CF3SO3minus 594









000 005 010 015 020 025

Total DMSO

Free

H-bonded

Free

H-bonded

Total PC

Anion H-bonded

Self H-bonded


005 010 015 020 025000

00

02

04

06

08

10

c i(m

ole f

ract

ion)

00

02

04

06

08

10

c i(m

ole f

ract

ion)



Free

Total DMC

H-bonded

LiClO4-DMC

00

02

04

06

08

10

c i(m

ole f

ract

ion)

005 010 015 020 025000


DMSODMCPC

010 015 020 0250050

2

4

6



(mole fractions)


nCl

O4minus







I iso

(arb

uni

ts)



minus100

10

I exp

minus

I cal

c 0

150

300

450




DMSO PC DMC120576 4724 [11] 6492 [2] 3107 [2]DN 298 [16] 151 [51] 172 [51]


119866 (119905) = int+infin

minusinfin

119868 (]) exp (2120587119894119888]119905) 119889] (4)






119866 (119905) = exp

minus[(1199052 + 12059121)12 minus 1205911]1205912

(6)




Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiBF4-DMSO

000

005

010

015

020

025

010 020000cLiBF4

(mole fraction)

(a)

Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiCF3SO3-DMSO

000

005

010

015

020

025

010 020000cLiCF3SO3

(mole fraction)

(b)

FreeIP

c i(m

ole f

ract

ion)

LiB(C2O4)2-DMSO

000

005

010

015

020

025

010 020000cLiB(C2O4)2

(mole fraction)

(c)

FreeIP

c i(m

ole f

ract

ion)

LiN(SO2CF3)2-DMSO

000

005

010

015

020

025

010 020000cLiN(SO2CF3)2

(mole fraction)

(d)

FreeSSIPCP

c i(m

ole f

ract

ion)

LiClO4-DMSO

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(e)



c i(m

ole f

ract

ion)

LiClO4-PC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(f)



c i(m

ole f

ract

ion)

LiClO4-DMC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(g)



4 Conclusion






Free anion005 2171 0710b01 2101 0782b015 1901 0463b02 1641 0249b025 1411 0162b



Free anionsSSIPCIP

2 4 6 8 100t (ps)

00

05

10

GV(t)





Competing Interests


Acknowledgments


References




































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Solvating DMSO

Dimeric DMSO

MonomericDMSO

Three lines

Iso

Solvating DMSO

Free DMSO

Two lines

Iso

Inte

nsity

(arb

uni

ts)


0

1000

2000

3000

4000

0

1000

2000

3000

4000

Inte

nsity

(arb

uni

ts)660 680 700 720 740640



minus100

10

I exp

minus

I cal

c

minus200

20

I exp

minus

I cal

c






NO3minus 653

BF4minus 602

ClO4minus 594

CF3SO3minus 594









000 005 010 015 020 025

Total DMSO

Free

H-bonded

Free

H-bonded

Total PC

Anion H-bonded

Self H-bonded


005 010 015 020 025000

00

02

04

06

08

10

c i(m

ole f

ract

ion)

00

02

04

06

08

10

c i(m

ole f

ract

ion)



Free

Total DMC

H-bonded

LiClO4-DMC

00

02

04

06

08

10

c i(m

ole f

ract

ion)

005 010 015 020 025000


DMSODMCPC

010 015 020 0250050

2

4

6



(mole fractions)


nCl

O4minus







I iso

(arb

uni

ts)



minus100

10

I exp

minus

I cal

c 0

150

300

450




DMSO PC DMC120576 4724 [11] 6492 [2] 3107 [2]DN 298 [16] 151 [51] 172 [51]


119866 (119905) = int+infin

minusinfin

119868 (]) exp (2120587119894119888]119905) 119889] (4)






119866 (119905) = exp

minus[(1199052 + 12059121)12 minus 1205911]1205912

(6)




Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiBF4-DMSO

000

005

010

015

020

025

010 020000cLiBF4

(mole fraction)

(a)

Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiCF3SO3-DMSO

000

005

010

015

020

025

010 020000cLiCF3SO3

(mole fraction)

(b)

FreeIP

c i(m

ole f

ract

ion)

LiB(C2O4)2-DMSO

000

005

010

015

020

025

010 020000cLiB(C2O4)2

(mole fraction)

(c)

FreeIP

c i(m

ole f

ract

ion)

LiN(SO2CF3)2-DMSO

000

005

010

015

020

025

010 020000cLiN(SO2CF3)2

(mole fraction)

(d)

FreeSSIPCP

c i(m

ole f

ract

ion)

LiClO4-DMSO

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(e)



c i(m

ole f

ract

ion)

LiClO4-PC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(f)



c i(m

ole f

ract

ion)

LiClO4-DMC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(g)



4 Conclusion






Free anion005 2171 0710b01 2101 0782b015 1901 0463b02 1641 0249b025 1411 0162b



Free anionsSSIPCIP

2 4 6 8 100t (ps)

00

05

10

GV(t)





Competing Interests


Acknowledgments


References




































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


000 005 010 015 020 025

Total DMSO

Free

H-bonded

Free

H-bonded

Total PC

Anion H-bonded

Self H-bonded


005 010 015 020 025000

00

02

04

06

08

10

c i(m

ole f

ract

ion)

00

02

04

06

08

10

c i(m

ole f

ract

ion)



Free

Total DMC

H-bonded

LiClO4-DMC

00

02

04

06

08

10

c i(m

ole f

ract

ion)

005 010 015 020 025000


DMSODMCPC

010 015 020 0250050

2

4

6



(mole fractions)


nCl

O4minus







I iso

(arb

uni

ts)



minus100

10

I exp

minus

I cal

c 0

150

300

450




DMSO PC DMC120576 4724 [11] 6492 [2] 3107 [2]DN 298 [16] 151 [51] 172 [51]


119866 (119905) = int+infin

minusinfin

119868 (]) exp (2120587119894119888]119905) 119889] (4)






119866 (119905) = exp

minus[(1199052 + 12059121)12 minus 1205911]1205912

(6)




Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiBF4-DMSO

000

005

010

015

020

025

010 020000cLiBF4

(mole fraction)

(a)

Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiCF3SO3-DMSO

000

005

010

015

020

025

010 020000cLiCF3SO3

(mole fraction)

(b)

FreeIP

c i(m

ole f

ract

ion)

LiB(C2O4)2-DMSO

000

005

010

015

020

025

010 020000cLiB(C2O4)2

(mole fraction)

(c)

FreeIP

c i(m

ole f

ract

ion)

LiN(SO2CF3)2-DMSO

000

005

010

015

020

025

010 020000cLiN(SO2CF3)2

(mole fraction)

(d)

FreeSSIPCP

c i(m

ole f

ract

ion)

LiClO4-DMSO

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(e)



c i(m

ole f

ract

ion)

LiClO4-PC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(f)



c i(m

ole f

ract

ion)

LiClO4-DMC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(g)



4 Conclusion






Free anion005 2171 0710b01 2101 0782b015 1901 0463b02 1641 0249b025 1411 0162b



Free anionsSSIPCIP

2 4 6 8 100t (ps)

00

05

10

GV(t)





Competing Interests


Acknowledgments


References




































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


I iso

(arb

uni

ts)



minus100

10

I exp

minus

I cal

c 0

150

300

450




DMSO PC DMC120576 4724 [11] 6492 [2] 3107 [2]DN 298 [16] 151 [51] 172 [51]


119866 (119905) = int+infin

minusinfin

119868 (]) exp (2120587119894119888]119905) 119889] (4)






119866 (119905) = exp

minus[(1199052 + 12059121)12 minus 1205911]1205912

(6)




Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiBF4-DMSO

000

005

010

015

020

025

010 020000cLiBF4

(mole fraction)

(a)

Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiCF3SO3-DMSO

000

005

010

015

020

025

010 020000cLiCF3SO3

(mole fraction)

(b)

FreeIP

c i(m

ole f

ract

ion)

LiB(C2O4)2-DMSO

000

005

010

015

020

025

010 020000cLiB(C2O4)2

(mole fraction)

(c)

FreeIP

c i(m

ole f

ract

ion)

LiN(SO2CF3)2-DMSO

000

005

010

015

020

025

010 020000cLiN(SO2CF3)2

(mole fraction)

(d)

FreeSSIPCP

c i(m

ole f

ract

ion)

LiClO4-DMSO

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(e)



c i(m

ole f

ract

ion)

LiClO4-PC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(f)



c i(m

ole f

ract

ion)

LiClO4-DMC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(g)



4 Conclusion






Free anion005 2171 0710b01 2101 0782b015 1901 0463b02 1641 0249b025 1411 0162b



Free anionsSSIPCIP

2 4 6 8 100t (ps)

00

05

10

GV(t)





Competing Interests


Acknowledgments


References




































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiBF4-DMSO

000

005

010

015

020

025

010 020000cLiBF4

(mole fraction)

(a)

Free1st IP2nd IP

c i(m

ole f

ract

ion)

LiCF3SO3-DMSO

000

005

010

015

020

025

010 020000cLiCF3SO3

(mole fraction)

(b)

FreeIP

c i(m

ole f

ract

ion)

LiB(C2O4)2-DMSO

000

005

010

015

020

025

010 020000cLiB(C2O4)2

(mole fraction)

(c)

FreeIP

c i(m

ole f

ract

ion)

LiN(SO2CF3)2-DMSO

000

005

010

015

020

025

010 020000cLiN(SO2CF3)2

(mole fraction)

(d)

FreeSSIPCP

c i(m

ole f

ract

ion)

LiClO4-DMSO

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(e)



c i(m

ole f

ract

ion)

LiClO4-PC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(f)



c i(m

ole f

ract

ion)

LiClO4-DMC

000

005

010

015

020

025

010 020000cLiClO4

(mole fraction)

(g)



4 Conclusion






Free anion005 2171 0710b01 2101 0782b015 1901 0463b02 1641 0249b025 1411 0162b



Free anionsSSIPCIP

2 4 6 8 100t (ps)

00

05

10

GV(t)





Competing Interests


Acknowledgments


References




































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




Free anion005 2171 0710b01 2101 0782b015 1901 0463b02 1641 0249b025 1411 0162b



Free anionsSSIPCIP

2 4 6 8 100t (ps)

00

05

10

GV(t)





Competing Interests


Acknowledgments


References




































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

review article speciation in solutions of lithium salts in

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