Reversible Energy Storage in Layered Copper-Based Coordination Polymers: Unveiling the Inuence of the Ligand's Functional Group on their Electrochemical Properties
Coordination polymers represent a suitable model to study redox mechanisms in materials where both metal cation and ligand undergo electrochemical reactions and are capable to proceed through reversible multielectron-transfer processes with insertion of cation and anion into their open structures. Designing new coordination polymers I for electrochemical energy storage with improved performance relays also on the understanding of their structure-properties relationship. Here, we present a family of copper-based coordination polymer with hexafunctionalized benzene ligands forming a kagome-type layered structure, where the inuence of the functional groups in their structure and electrochemical properties is investigated. Their chemical and structural properties have been explored by means of PXRD, and FTIR and Raman spectroscopies, followed by investigation of their electrochemical performance in Li half-cells by CV and galvanostatic cycling techniques. Ex-situ PXRD, Raman, XPS and ToF-SIMS measurements of cycled electrodes have been carried out providing insights into the redox mechanism of these copper-based coordination polymers as positive electrode materials.
Introduction<!>Synthetic protocols
<p>inergy storge systems hve eome uiquitous in n inresingly energyEdependent soietyD where energy storge tehnology is plying key role in the uptke of intermittent renewle energy soures nd in the development of zero gy 2 emission eletri vehilesF 13 he mrket is urrently dominted y viEion tteries owing to their high energy densityD sene of memory e'et nd long yle stilityF 4 ith new moile pplitionsD suh s eletri vehilesD pushing further the limits of urrent viEion tehnologyD severl ottleneks need to e tkled in order to inrese the ttery energy densityF ome of theseD inlude inresing the spei( pity of the thode mterilD urrently limited to <QHH meh g −1 in stteEofE theErt trnsition metl @wA lyered oxidesF 5,6 purthermoreD there is lso desire to pursue thodes mterils shifting wy from toxiD expensive nd geopolitilly restrined wsF 7 goordintion polymers n present multieletron redox pilities where othD the metl tions nd the nonEinnoent lignd moieties n undergone redox retionsD 8,9 lso llowing for wide rnge of metl tions nd lignds to onform the oordintion frmework to tilor their struture nd eletrohemil propertiesF 1015 his multieletron redox pility toE P gether with the open frmework struture presented y this lss of mterilsD llows for oth viEion nd nion @deAinterltionD inresing the numer of eletrons trnsferred etween thode nd nodeD nd hene the ttery pityF 1621 his desired dulEion pility whih provides higher energy densitiesD exelling those of trditionl singleEion tive mteE rilsD re more suitle for oordintion polymers with open frmeworks providing plenty of spe to ommodte for nionsD usully lrger thn their tions ounterprtsF 22 reneD understnding the strutureEproperties nd the e'et of the funtionl groups present in the oordinting lignd moieties onforming the oordintion polymers is pivotl to design enhned mterils with improved funtionlitiesF ith plethor of di'erent possiilities to form redoxEtive oordintion polymersD 23 new fmily of oordintion polymer with the formul unit @w 2+ A 3 @v 3 A 2 nd kgomeE type lyered struture hs reently een reported s eletrode mterils for vrious ttery hemistriesD inluding viEionD xEion nd nEirF 2426 rtiulrlyD the xi 3 @rsfA 2 oordinE tion polymer ws reported s multieletron thode mteril for viEion tteries with pE ities up to ISH meh g −1 nd long yling stilityF 26 hese @w 2+ A 3 @v 3 A 2 lss of mterils with kgomeEtype struture present hexsustituted enzene lignds whih re oordinted to three metl ions in squreEplnr oordintion geometryD forming twoEdimension lyE ered struture of ornerEshring tringlesD with the lyers pking in prllel in elipseD stked or intermedite slipped on(gurtions @pigF IAF rereD we explore the eletrohemil properties of three nlogous gu 3 v 2 oordintion polymersD exploring the e'et of repling the imine oordintion moieties in the hexfunE tionlized enzene lignd progressively y loxy moieties s shown in pigure I@dEfAF por this purposeD we hve prepred the gu 3 @rsfA 2 @rsf a heximinoenzeneA nd gu 3 @refA 2 @hexE loxyenzeA oordintion polymersD nd the gu 3 @sqA 2 @triiminophlorogluinolA iminoGloxy mixed intermedite mterilF he in)uene of the di'erent lignds on the resulting oordiE ntion polymer strutureD their eletrohemil performne s positive eletrode in dulEion lithium tteries nd the redox mehnism ourring during yling hve een studied y Q pigure IX grystl struture of the w 3 @rsfA 2 mteril showing the oordintion environment formed etween the metl nd the lignd @AD the polymeristion of the se unit long forming lyer @A nd the pking of the three dimension of the oordintion lyersD in this se in n elipsed on(gurtion elonging to the P TGmmm rystl spe group @AF @dEfA hemti representtion of the three guEv hemil entities prepred in this workF grystllogrphi representtions reted with ie version Q softwreF 27 R ex-situ hD mnD nd opEsw tehniquesF</p><!><p>ell hemils nd solvents for the mterils syntheses were purhsed from unto ghemil goF snFD igmEeldrih goF nd ko ure ghemil sndustries vtdD nd used without further puri(tionF he synthesis of the gu 3 @rsfA 2 oordintion polymer ws rried out following previous reportsF 28,29 frie)yD in n rgonE(lled glove oxD two seprte solutions of gu@eyA 2 • r 2 y @HFIHV mmolD PP mgA in hwy @TFT gA nd mmoni @QS7volD RFS mvAD nd hexminoenE zene trihloride @refA @HFHUP mmolD PH mgA in degssed hwy @TFT gA nd degssed mE moni @QS7volD RFS mvA were mixed into PH mv sintilltion vil nd left overnight t TH o g with prtilly opened p to llow slow oxygen di'usion from the oven ir tmosphereF e lk powder preipitted nd susequently wshed with wter nd etone vi entrifuE gtion nd denttionF pinllyD the mteril ws dried overnight under vuum t IIH o gF he gu 3 @sqA 2 intermedite mteril ws prepred in similr mnner to the gu 3 @rsfA 2 mterilF sndividul solutions of gu@eyA 2 • r 2 y @HFIHV mmolD PP mgA in hwy @TFT gA nd mmoni @QS7volD RFS mvAD nd triminophlorogluinol @eqA @HFHUP mmolD PQ mgA in degssed hwy @TFT gA nd degssed mmoni @QS7volD RFS mvA were mixed into PH mv sintilltion vil nd left overnight t TH o g with prtilly opened p to llow slow oxygen di'usion from the oven ir tmosphereF e lkGdrk rown powder preipitted nd suE sequently wshed with wter nd etone vi entrifugtion nd denttionF pinllyD the mteril ws dried overnight under vuum t IIH o gF por the preprtion of the eq ligndD the synthesis ws rried y idi nitrtion of phlorogluinol followed y reduE tion with hydrogen tlyzed y d supported on ron @I7wtA @heme IA following S report from udek nd öhmF 30 uessful synthesis of the trgeted eq lignd ws on(rmed y 1 r xw nd 13 g xw @pigsF I nd PAF st hs to e noted tht for the synthesis of the eq ligndD potentilly explosive trinitroenzeneEderivtes re produedD nd in onsequeneD mximized sfety mesuresD s well s synthesis of minimum s possile quntities of the mterils synthesizedD re enourgedF he synthesis of the gu 3 @refA 2 oordintion polymer ws rried out following the protool reported y rk et al. 31 sn riefD to solution of tetrhydroxyquinone @QHH mgD IFUR mmolA in degssed wter @IHH mvAD degssed queous solution @IHH mvA of gu@eyA 2 • r 2 y @RSU mgD PFPW mmolA nd ethylenedimine @HFPQ mvD QFRS mmolA ws dded under nitrogen tmosphere nd stirred overnight t room tempertureF e drk nvy powder preipittedD nd it ws wshed with wter nd etone vi entrifugtion nd denttionF pinllyD the mteril ws dried overnight under vuum t IIH o gF pollowing the originl reportD the mteril ws wshed with wter t TH o g for IP hours to mximize the removl of guest speies on the oordintion polymerF gu@g 6 xryA 2 gu@sA 2 @pigF QA ws synthesized following n nlogous protool to tht for the deprotonted xi@minothiophenolA 2 reported in the litertureF 32 oEminophenol @RQU mgD R mmolA nd uyr @PPH mgD R mmolA were dded dissolved in queous ethnol @PH7volD IH mvA nd solution of gu@eyA 2 • r 2 y @QWW mgD PmmolA in PFS w mmoni ws dded dropwise to the formerF he preipitted protonted mteril ws isolted y (ltrtion nd dded to uyr @RHH mgA queous solution @QH mvA nd stirred overnight under irF pinllyD the lk mteril ws (ltrted nd wshed with wterD ethnol nd etoneF h of the resulting deprotonted gu@sA 2 mteril mthed with tht of the protonted mteril nd reported rystl struture 33 with olour hnge due to rdil formtion during deprotontion @pigF RAF T Characterization 1 r nd 13 g nuler mgneti resonne @xwA dt were olleted on tiyv txwEigRHH spetrometer using hwyEd 6 s deuterted solventF ilementl nlyses @gD rD nd xA were otined from vrio wsgy ue @ilementr enlysensysteme qmrA instrumentF h mesurements were rried out on igku mrtv Qk di'rtometer using gu uα rE dition with step size of HFHP o F mn spetr were mesured y vew r ivolution @rysfe ienti(A equipped with rexe TQQ nm lserF pourierEtrnsform infrred @psA spetr were otined in xiolet iSH pEs @hermo pisher ienti(A on mterils pelE letized with ufr in trnsmission modeF Ery photoeletron spetrosopy mesurements were onduted on rs SHHH ers roe @vegErs snFA instrument with el uα @IS kD PSA soure with emEirrdited re of IHH µm 2 t RRFH o F he spetr were nlyzed using wultik oftwre nd (ts to the dt were rried out using qussinEvorentzin symmetri urves with hirleyEtype kgroundF por the eletrohemil hrteristion of the opperEontining oordintion polymers s eletrode mterilsD oin ellEtype tterE ies were prepredF lurries of oordintion polymer s tive mterils @UH7A mixed with multiwlled ron nnotues @PH7A nd dp @IH7A s inder were st on el foil nd dried under vuum for PR hours t IQH o gF gron pper @qErEHQHD ory sndustriesD snFA ws dded on top of the eletrode to inrese eletroni ondutivity t the eletrode surfe nd gelgrd PQPS polymerEsed ws employed s seprtor with lithium metl s ounter nd referene eletrodesF I w vip 6 in ethylene ronteGdiethyl ronte @QXUA ws used s eletrolyte in )ooded ellsF he loding mount of tive mteril on the el foil ws lose to I mg m −1 in ll smplesF he eletrohemil mesurements were rried out in multihnnel wEQ @fioEvogi ienti( snstrumentsA potentiosttF por ex-situ mesurementsD the ells were yled t S me g −1 D stopped t the trgeted voltge nd suE sequently disssemled inside of n erE(lled glove ox where the eletrodes were thoroughly wshed with dry rpF hepth pro(les were mesured using opEsw S @syxEypD qerE mnyA instrument in dul em interled modeD in positive polrity for vi trns geometries for the mononuler gu@sqA 2 omplex were performed with qussin HW evision iFHI softwreD 34 using the feke threeEprmetri hyrid exhnge @fQA together with the veeEngErr orreltion funtionl @vA 35,36 nd TEQIq sis setF 37</p><p>Results and discussion he synthesis of the three opperEontining oordintion polymers studied here followed metlElignd omplextion retion preeding ontrolled oxidtive deprotontion in irF 28,3840 sn the se of the gu 3 @rsfA 2 nd gu 3 @refA 2 mterilsD the synthesis ws rried out ording to estlished protools previously reported in the litertureD 28,31 nd suess on the retion ws orroorted y h @pigF PAD with di'rtion ptterns indexed to the C PPP 1 nd Cmcm spe groupsD respetivelyF sn the se of the gu 3 @sqA 2 mterilD there re no previous reports on its synthesis nd hene severl syntheti onditions were tE tempted to produe the trgeted oordintion polymerF terD ethnol or dimethylsulfoxide s were tested s solvent with mmoniD potssium hydroxide or ethylenedimine s sesD nd ir or opper@ssA slt s oxidntsF prom the di'erent syntheti protools ttemptedD none of then produed fully rystlline mterils with only the nlogous syntheti pthwy to tht of gu 3 @rsfA 2 preluding the pperne of impurities while llowing to retin some rystllinity @pigF PAF sing wter nd ethylenedimineD similrly s in the se of the synthesis of the gu 3 @refA 2 mterilD resulted in the formtion of gu 2 yF he use of the sq ligndD with oth hydroxy nd mino groupsD led to onsiderle derese in the rystllinity of the prepred mterilF es oserved in pigure PD prtil repling of the hexE V minoenzene lignd with triminophlorogluinolD produes derese on the mjority of the frgg re)etions9 intensitiesD with only the re)etion due to the interlyer sping remining fter totl sustitution of the hexminoenzene lignd y the triminophlorogluinol ligndF his indites tht while the lyered struture is retinedD the inEplne struture disorders onsiderlyF mn nd ps spetrosopies pigsF P@DdA were employed to proe the hemil moiE eties present in the semiEmorphous gu 3 @sqA 2 mterilF o help to sertin the nture of the moieties present in the gu 3 @sqA 2 mterilD the spetr were ompred with those of the gu 3 @rsfA 2 oordintion polymerD synthesized y the sme protoolD nd with the opper is@oEiminophenolA mononuler omplex gu@sA 2 F here re ler shred fetures etween oth gu 3 @rsfA 2 nd gu 3 @sqA 2 with nds in the regions of QUSHEQHHH m −1 nd IUSHEIHHH m −1 ttriuted to xGy r strethings nd gGxGy g strethingsD respetivelyF 28,41 sn the sme mnnerD the mononuler omplex lso showed virtion nds in the sme regionsD inditing tht the gu 3 @sqA 2 oordintion polymerD while morphous inEplneD presents the expeted oordintion etween gu nd the triiminophlorogluinol ligndD together with lyered struture s glimpsed from the presene of the retined @HHPA re)etion in the h dtF sn order to gin further insights on the possile oordintion of the sq lignd round the opper tionsD hp lultions on the mononuler nlogue with oth is nd trns on(gurtion were preformed showing tht the trns on(gurtion is ≈IHH me more fvourle @pigF SAF gompring to similr moleulr omplexesD rsd et al. reE ported the IEh gu 2 @µEdd@ddrA 2 A @dd a PDSEdiminoEQDTEdihloroEIDREenzoquinoneA oordintion polymerD where opper tions oordinte to the lignd in squre plnr geometry with the minophenolEderivtive lignd oordinting in trnsEgeometryD so it is expeted this on(gurtion to e predominnt in the gu 3 @sqA 2 mterilF 42 ilementl nlyses @le IA were employed to investigte the presene of guest moleules entrpped inside the oordintion polymers9 frmeworkF sn line with previous reportsD gu 3 @rsfA 2 presented lower perentge of g nd x thn expeted tht is ttriuted to W pigure PX @A h of the gu 3 @rsfA 2 D gu 3 @sqA 2 D gu 3 @refA 2 nd mixed lignd gu 3 @rsfA@sqA oordintion polymersF @A h of the di'erent produts resulting from the vrious syntheti onditions @solventD seD oxidntA ttempted for the gu 3 @sqA 2 oE ordintion polymerF @A ps spetr of the gu 3 @rsfA 2 D gu 3 @sqA 2 nd the gu@sA 2 mterilsF @dA mn spetr of the gu 3 @rsfA 2 D gu 3 @sqA 2 nd the gu@sA 2 mterilsF B denotes metlli f gu @spe group Fm 3mA nd 5 represents re)etions rising from gu 2 y uprite mteril @spe group Pn 3mAF</p><p>IH presene of wter moleules whih n oordinte to the gu ions or hydrogenEond to the imine groupsF 25 por the gu 3 @refA 2 mterilD higher perentge of x thn expeted ws oservedD whih ginD is in line with previous reports nd indites presene of ethylenediE mine entrpped in the poreF 31 sn the se of the gu 3 @sqA 2 mterilD x is lso slightly higher thn expet nd similrly to the gu 3 @refA 2 mterilD mine moieties ould e enE trppedD in this seD xr + 4 from the retion mediF fi mesurements showed similr surfe res for the three mterils @pigF TA in the sme order of mgnitude rnging from</p><p>he eletrohemil performne of the three opperEontining oordintion polymers s positive eletrode for lithium tteries ws evluted y g nd glvnostti yling in viEhlf ells @pigF QAF g urves of the three mterils in the PFS E RFPS rnge showed severl redox wvesD with the more pronouned peks eing ove Q vs viGvi + for the three mterilsF por the purpose of energy storgeD the higher voltge redox ouples re the most interestingD nd hene the fous in the nlysis of theseF por the gu 3 @rsfA 2 mterilD the higher potentil redox ouple ours t QFWGQFV @oxidtionGredutionAD whih is HFP higher thn tht found for the xi 3 @rsfA 2 nlogue mterilD 26 similrly s reported for the vi@xiGguAy 2 mterilsD where n inrese of ≈HFR is oserved when repling nikel with opperF 43 hifting from ll mine funtionlized lignd to the hlf mineGhydroxy funtionE lized lignd in the gu 3 @sqA 2 mteril produes derese on the operting voltge of the eletrodeD with the most intense redox ouple ppering t QFTGQFT F en dditionl oxiE dtion pek ove R is oservedD whih is further developed in the se of the gu 3 @refA 2 mteril @RFISGQFWS A with the ll hydroxyEfuntionlized ligndD inditing its origin to the presene of oxygen nions in these two mterilsF sn ddition to this >R redox oupleD the gu 3 @refA 2 mteril lso presents severl wellEde(ned redox ouplesD inditive more proessErih nd stepwise redox mehnismD whih n e lso oserved on the glvnostti pro(le @pigF QA where severl pseudoplteus re presentD in omprison with the more sloppy pro(les of the gu 3 @rsfA 2 nd gu 3 @refA 2 mterilsF II pigure QX iletrohemil hrteristion of the three opperEontining oordintion polyE mers studiedF @A S th yli voltmmogrms of the three oordintion polymers t HFI m s −1 etween PFS nd RFPS F @A S th glvnostti yling pro(le t S me g −1 etween PFS nd RFPS F @A gyling stility nd oulomi e0ienies t S me g −1 etween PFS nd RFPS during PH ylesF @dA te pility test for the gu 3 @rsfA 2 nd gu 3 @sqA 2 mterilsF g urves hve een resled in other to e in the sme rngeF IP ithin the voltge rnge studiedD gu 3 @rsfA 2 mteril delivers n initil pity just ove IHH meh g −1 @pigF QA followed y smll derese during the (rst S yles whih then is followed y progressive inrese up to ner PHH meh g −1 eyond yle IS when yled t S me g −1 F sn ddition to the inresed operting voltge when repling xi with gu in w 3 @rsfA 2 D the pity of the gu 3 @rsfA 2 mteril in lso inresed when yled in similr voltge rnge @<UH meh g −1 for xi 3 @rsfA 2 when yled etween PFSERFS AF 26 gonsidering the moleulr weight of the mterilD IHR meh g −1 per @deAinserted ion n e otined theoretillyD inditing tht the oserved pity orresponds to two eletron trnsferred per hrge or dishrgeF gu 3 @sqA 2 mteril showed lower spei( pity ner RH meh g −1 whih is mintined during the whole yling testF sn the se of the gu 3 @refA 2 mterilD the (rst hrge yle showed lrge plteu ove R @>SHH meh g −1 A whih n not e explined solely in terms of reversile metl or lignd redox proesses without onversion retions @pigF UAF 10,44,45 purthermoreD the ells were unle to yle eyond the sixth yle @pigF UA whih indites deomposition of the mteril ndGor eletrolyte hd pleF 46 sn prllel to this studyD ting et al. hve reently reported the eletrohemil properties of the gu 3 @refA 2 mteril yled t di'erent voltge windowD lso oserving n rupt derese on the ell performne when solely inresing the upper potentil from RFH to RFI F 47 goulomi e0ienies for the gu 3 @rsfA 2 nd gu 3 @sqA 2 mterils during the (rst yle hd vlues ove PHH7D inditive of prsiti retions during the (rst yleD stilising then t slightly ove IHH7 in the susequent ylesF sn the se of the gu 3 @refA 2 mterilD oulomi e0ienies re ner SH7 were oservedD inditing only hlf reversiility of the hrging proessF imilr e'et n e oserved in inorgni lyeredEoxide mterils where irreversile oxygen redox tivity is present t high voltgesF 46,48,49 te pility tests were rried out for the gu 3 @rsfA 2 nd gu 3 @sqA 2 mterils whih were le to withstnd longer yling @pigF QdAF he tests showed low rte pility for the gu 3 @rsfA 2 mteril with pronouned derese of the dishrge pity elow PH meh IQ g −1 when inresing the yling rte to PSH me g −1 F gu 3 @sqA 2 mteril showed more stleD rte pilityD lthough the pity remined low t ll rtesF sn oth mterilsD the pity is reovered when the yling rte is redued fter the high rte ylesF st hs to e notedD tht higher pity up to VH meh g −1 n e hieved y the gu 3 @sqA 2 mteril when widening the yling voltge window to RFSEPFI D howeverD this ours t expense of the yling reversiility whih experienes derese in the oulomi e0ieny to WS7 @pigF VAF o further investigte the ioni di'usion in the studied opperEontining oordintion polymersD the ndlesEevik eqution ws employed to nlyze g mesurements t vrious snning rtes @pig WAF he intensities of the oveEdesried redox ouples were nlyzed in funtion of the sn rte nd the lulted di'usion oe0ients re displyed on le PF he di'usion oe0ients otined re in the order of IH −11 to IH −10 m 2 s −1 D with overll higher di'usion oe0ient in oth oxidtion nd redution sides of the higher voltge redox wve for the gu 3 @rsfA 2 mterilF o on(rm p 6 interltion during hrge t the higher voltge redox pekD opEsw mesurements on the est performing mterilD gu 3 @rsfA 2 D were rried out ex-situ in yled eletrodes @pigF RAF he dt lerly shows tht inresing the ell potentil to RFPS leds to p 6 insertion s oserved y the higher mount of p 6 deteted on the hrged eleE trode ompred with the residul mount of p 6 found on the nonEyled nd dishrged eletrodesF purthermoreD vi + ws deteted on the dishrged eletrodeD on(rming vi + interE ltionD while only smll tres of vi + were deteted for the neutrl nd hrge eletrodesF hese results on(rm the dulEion storge pility in this opperEontining oordintion polymer nd hene is expeted tht plying with the eletrolyte ompositionsD improved</p><p>pilities n e relizedF Ex-situ hD mnD nd mesurements were lso rried out on yled eleE trodes t dishrgeD neutrl nd hrged sttes to sertin the possile eletrohemil redox mehnism during ylingF h nlyses @pigF IHA demonstrted roust rystl struE IR pigure RX Ex-situ opEsw depth pro(les of p 6 nd positive ions vi + of gu 3 @rsfA 2 hrgedD neutrl nd dishrged gu 3 @rsfA 2 eletrodes t S me g −1 etween PFS nd RFPS F IS pigure SX golumn hrt representing the tomi perentge @vertil xisA of eh di'erent omponents present in eh edge mesured t three hrge sttes dishrged @PFSH AD neutrl @ygA nd hrged @RFPS A for the three oordintion polymers studied here s otined from (ttings to the dt @ges VEIID isA nd ssigned ording to the litertureF 25,5053 IT ture with no oservle morphistion or dditionl frgg re)etionsD reveling the sene of phse trnsformtions or detrimentl onversion retionsF sn dditionD no oservle displement of the frgg re)etions is oservedD inditing tht the pores nd interlyer distne provides enough spe for ion insertion without detrimentl volume hngesF por the gu 3 @refA 2 oordintion polymerD the ex-situ h mesurements demonstrted the stility of the mteril fter hrgingD inditing deomposition of the eletrolyte s ulprit of ell deteriortionF o determine ny hnges in the hemil struture of the oordintion polymersD ex-situ mn spetrosopy of yled eletrodes ws lso performed @pigF UAF por gu 3 @rsfA 2 nd gu 3 @refA 2 mterils there is ler derese in the rtio etween the nd ttriuted to the gu xGy virtions @ RPS m −1 A with respet to the nd relted to romti ring virtions @ IIHH to IUHH m −1 A when the mterils re eletrohemilly oxidizedF yn the other sideD while there re some oservle hnges in the mn nds of the gu 3 @sqA 2 mterilD these re less pronouned nd don9t follow progressive hnge from redue to oxidized sttesF he hnges in the reltive intensity etween gu xGy nd romti ring virtion modes n e ttriuted to the oxidtion of the lignd whih results in doping with holes on the romti ringD s previously oserved in the litertureD 5456 inE diting more iminl @g xA @gu 3 @rsfA 2 A or quinoid @g yA @gu 3 @refA 2 A ntureF st hs to e noted tht virtions rising from the wgx employed s ondutive dditive to the eletrode overlp with the lignd9s romti ring virtions nd so ontriution of these nnot e fully disrdedF o further lrify the yling mehnism nd hnges on the hemil entities forming the oordintion polymerD ex-situ nlyses were performed @ges VEIID isAF o simplify the interprettion of the nlysesD individul ontriutions to the totl spetrum of eh element nlyzed for the three di'erent mterils t three di'erent sttes re summrized in pigure SF ritions on the gu Pp 3/2 reveled low inrese of round T7 of gu@ssA respet to gu@sA etween redution nd oxidtion in the gu 3 @rsfA 2 while the gu 3 @sqA 2 showed higher hnge ner QH7 in the proportion of gu@ssA when the mteril is oxidizedF IU sn the se of the gu 3 @refA 2 mterilD lrge inrese of gu@sA of out RQ7 is oserved upon redution from neutrl stteF st ws lso deteted IP7 inrese on gu@sA during oxidtion of the mterilsD whih is in greement with other lyered oxide thode mterils where oxygen nioni redox tivity is oservedF 57 woving to the xIs dtD in the se of the gu 3 @rsfA 2 mterilD three nds where oserved whih were ssigned to g xr − D g xr nd g xr + D while in the se of the gu 3 @sqA 2 only the nd ssigned to g xr ws detetedF he nds ssigned to the gu 3 @refA 2 mterils follow ler progressive trend of inresing ontriution of the g xr moieties nd holes @g xr + A with mteril oxidtionF his is in good greement with previous reports on go 3 @rsfA 2 where similr vrition etween enzoid nd quinoid nitrogen toms ws oserved during redox retionsF 25 yn the other sideD there were no hnges deteted in the xIs spetr during yling of the gu 3 @sqA 2 mterilD inditing lk of redox retivity entred t the ligndF sn the se of the gIs spetrD the lerer hnges re produed in the rtio of g g nd g g where for the gu 3 @rsfA 2 nd gu 3 @refA 2 n inresing proportion of g g is oserved with oxidtion of the mterilsD while in the se of the gu 3 @sqA 2 oordintion polymer these tend to e onstntF here is lso ler inrese in the ronte speies in the se of the gu 3 @refA 2 mteril inditingD one ginD the higher retivity of the mteril nd possile eletrolyte deomposition during the hrging proessF yxygen nlyses were not rried out due to the presene of dsored oxygen whih preluded the orret of signlsF prom the nlysesD it is ler tht while in the se of the gu 3 @sqA 2 oordintion polymer the retion is minly foused in the gu tionD in the gu 3 @rsfA 2 nd gu 3 @refA 2 mterils this hs ontriution from othD the metl tion nd the ligndD where the prtiiption of the metl tion remins low in the se of the gu 3 @rsfA 2 mterilF his di'erent ehviour in the gu 3 @sqA 2 mteril showing minly metlEtion redox tivity is line with other opper minophenol omplexes where the redox tivity hs lso een found to e entred t the opper tionsF 58 his points to lower stility of the mixed quinoid resonnt strutures when oth loxy nd imine moites form prt of the lignd whih my fvours IV hrge loliztion onto the opper tionsF his lower ontriution from the lignd to the redox tivity n explin the lower pity oserved during the glvnostti ylingF prom these dtD it n e interpreted tht the redox mehnism underlying the eleE trohemil yling of these oordintion polymers is sed on the rerrngement of the moleulr doule onds whih relote from the g g in the romti rings towrds the formtion of lolized imine g x onds during oxidtion of the oordintion polymers s represented in pigure TF imilr redox mehnism hs lso een reported in other mononE ioni πErdil omplexes where trnsition from g g nd negtive hrged heteortoms towrds g g nd g upon oxidtionF 59 pigure TX hemti representtion fo the redox mehnism during yling of the opperE ontining oordintion polymers studied hereF huring eletrode dishrgeD vi + is inserted into the oordintion polymer frmework nd the doule ond shift to the romti ring while gu is reduedF huring eletrode hrgeD p 6 is inserted into the oordintion polyE mer struture nd the doule onds move wy from the romti ring to form imine or quinoid moieties while gu is oxidizedF o simplify the representtion only the metl nd the immedite oordintion environment is representedF gompring with other opperEontining oordintion polymersD suh s the gu@gxA IW @gx a tetrynoquinodimethneAD where reversile nion storge hs lso een demonE strtedD the oordintion polymers presented here yle via topotti insertion retion insted of detrimentl onversion retionsF 60 sn dditionD it hs een demonstrted tht the gu tions re redoxEtive nd form prt of the yling retionD while in the se of the gu@gxA mteril only intive gu@sA is presentD hmpering full utilistion of the redox pity in the mterilF he IEh opperEenzoquinoid oordintion polymer reported y ghen nd oEworkers lso presents redox tivity in othD lignd nd opper tionsD ut with gu@HAGgu@sA s the opper redoxEtive ouple whih produes lower operting voltE ge elow QFS D 61 demonstrting the importne of hving oth redoxEtive lignd nd gu@sAGgu@ssA redox ouple to mximize the energy densityF Conclusions o summriseD here we hve presented new opperEsed oordintion polymers s tive mterils for positive eletrode in dulEion lithium tteries nd eluidted the underpinning redox mehnism during ylingF e hve demonstrted the role of the lignd9s funtionl groups in the rystl strutureD where hving present oth hydroxy nd mino groups reE dued onsiderly the rystllinityF iletrohemil yling of the mterils hs shown tht pities ner PHH meh g −1 n e rehed y the gu 3 @rsfA 2 mteril while hving n ll loxyEfuntionlized oordintion polymer resulted in ell deomposition ove R F he redox mehnism hs een investigted y ex-situ hD mnD opEsw nd tehE niques nd demonstrted othD metl tion nd ligndD prtiiption in the redox retion to di'erent extends depending on the nture of the ligndD while retining the rystl struE ture upon vi + nd p 6 ion @deAinsertionF he insights otined in this study demonstrte the potentil of these type of oordintion polymers s tive mterils for dulEion tteries nd pointed out the importne of reful lignd hoie to mximize mteril9s performneF PH Acknowledgement</p>