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squarestructure,cubicstructure,secondhydridephase

By Francisco Davis,2014-10-15 11:18
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squarestructure,cubicstructure,secondhydridephase

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    HydrogenStorageMaterials

    Dr.Li-xinChenLiTel:0571-879511520571Email:lxchen@zju.edu.cnLaboratoryofHydrogenStorageMaterialsInstituteofMetallicMaterialsZhejiangUniversity

    LectureIV

    Ti-andZi-BasedHydrogenStorageAlloysTiZi-

    2

    I.BasiccharacteristicofTiandZrPositioninthe?ôBgroupofelementperiodictable 3

    I.BasiccharacteristicofTiandZr

    ThreeshapesforTiorZrinnature:crystalTi(?á??îÑ)spongeTi(º?ÃàîÑ)powderTi((?Û×?îÑ))crystalZr(?á??ï?)spongeZr(º?Ãàï?)powderZr((?Û×?ï?))

    ZrandHfarecommensalinnature

    4

    ?ò.Ti-basedHydrogenStorageAlloyTi2.1Ti-Hsystems

    H=?C34.5kcal/mol.H2(?C144.40kJ/mol.H2)MaximumcapacityCmax=4.177wt.%H2Ti-basedbinaryHSAsincludes:TiFe,TiNiTiMn2,TiCr2,TiCo2,????

    5

    ?ò.Ti-basedHydrogenStorageAlloyTi2.2TiFebasedalloys

    Ti-Febasedbinaryphasediagram

    Therearetwointermetallics:TiFe2:cannotabsorbhydrogen

    at78~573Kand6.5MPaH2.

    TiFe:canabsorb/desorbH2at

    roomtemperature.

    6

    2.2TiFebasedalloys1)Hydrogenationreaction(threesteps):

    Thereareonesolidsolutionphaseandtwohydridephases:(i)?Á-phase:cubicstructure,solidsolution,maxsolubility=0.1;(ii)?Â-phase:squarestructure,firsthydridephase,TiFeH1.04;(iii)?Ã-phase:cubicstructure,secondhydridephase,TiFeH1.95. 7

    2.2TiFebasedalloys

    2)P-C-Tcurve(P-Cisotherm)ofTiFe-Hsystem

    P-C-TofTiFe-Hsystem

    

    Pdes

    (MPa)

    

    AsT<55?æ,therearetwopressureplateausduetotwohydridephases.AsT>55?æ,thereisonlyonepressureplateauduetononcoexistenceof?Â-phaseand?Ã-phase(?Â?ú?Ãcontinuouslytransition)

    

    8

    2.2TiFebasedalloys

    3)Features:(1)highcapacityof1.86wt%(210ml/g)atroomtemperature;(2)goodthermodynamic???H=?C6.7kcal/mol.H2(?C28.04kJ/mol.H2);(3)goodkineticsafteractivation(highabsorption/desorptionrate);(4)lowcost(??20/kg.TiFe,??120/kg.LaNi5); 9

    2.2TiFebasedalloys

    (5)sluggishactivation(inactivity);(6)bighysteresisln(Pa/Pd)TiFe=0.64>ln(Pa/Pd)LaNi5=0.19;(7)easilybepoisonedbyO2,H2O,CO2,CO,Cl2,etc.

    HysteresisofP-C-TcurveforTiFe-Hsystem

    10

    2.2TiFebasedalloys

    4)Thecauseofpooractivation(1)somethingcovering(0.5~10nm);(2)lackofcatalysissites;(3)lowdiffusioncoefficientofhydrogen;(4)toughness.

    11

    2.2TiFebasedalloys

    5)Resolvents:(1)raisingreactiontemperature??heatedat400~450?æand10-3torrvacuum(2)raisingpressureofH2(3)surfacemodificationtreatment

    ??suchas:millingwithLaNi5;soakingtreatmentinacidoralkalisolution (4)non-stoichiometricalloying??suchasTi1+xFe(x=0.1~0.5)(5)multi-componentalloying

    12

    2.2TiFebasedalloys6)Multi-componentalloyingforTiFe(1)TernaryalloysTiFe1-xMx(M=Mn,Cr,Co,Cu,Zr,Ni,V,Al,Mo,Be,Mm)formsomesecondaryphaseonthesurfaceofalloy?ú?üactivationsuchas:TiFe1-xMnx(x=0.15or0.2)??

    formTiMn1.5secondaryphase?ú?üactivation,?ücapacity

    TiFe1-xCrx(x=0.05or0.1)??

    formTiCr2secondphase?ú?üactivation

    13

    2.2TiFebasedalloys

    Ti1+xFe+y%Mm(x=0~0.4;y=0~6.0)Asx=0.3andy=4.5,alloyhasgoodactivationandkineticsAsx=0.3andy=6.0,alloyhasmaximumdesorptioncapacity

    InitialhydridingcurvesofFeTi1.3+xwt%Mmalloys(x=1.5~6.0)atroomtemp.and4.0MPa. 14

    2.2TiFebasedalloys(2)Multi-componentalloysTiFe1-x-yMxNy(M,N=Mn,Ni,V,Al,Zr,Nb,Mm)?üactivationsuchas:TiFe0.8Ni0.15V0.05,TiFe0.8Ni0.15Nb0.05,TiFe0.8Mn0.15Zr0.05,etc.

    15

    2.2TiFebasedalloysTiFe1-xMxNy(M,N=Mn,Ni,V,Al,Zr,Nb,Mm)?üactivationsuchas:TiFe0.8Mn0.2V0.05,TiFe0.8Mn0.2Zr0.05,TiFe0.8Ni0.2Nb0.05etc.

    ThecharacteristicsofsomeTiFeMnMbasedalloys

    16

    2.2TiFebasedalloys

    Ti1-xMxFe0.85Mn0.15(M=Zr,V,Ca)??ZJU

    ZrorV:?üactivation,but?ýcapacity;Ca:noobviouseffect.

    InitialhydridingcurvesofthealloysTi1-xMxFe0.85Mn0.15(M=Zr,V,Ca)

17

    2.3Ti-Nibasedalloys(aselectrodematerials)Ti-

    Ti-Nibasedbinaryphasediagram

    TiNi3??cannotabsorbH2atnormaltemperatureTiNi,Ti2Ni??canabsorb/desorbH2atnormaltemperature

    18

    2.3Ti-NibasedalloysTi1)Binaryalloys(1)TiNi

    theoreticalcapacityCtheo=352mAh/g;effectivecapacityCmax=245mAh/gat50mA/g;highcyclingstabilityin6MKOH(C?ý2%after60cycles)

    19

    2.3Ti-NibasedalloysTi-

    (2)Ti2Ni

    theoreticalcapacityCtheo=434mAh/gforTi2NiH2.5;effectivecapacityCmax=~40%Ctheo=173mAh/g;badcyclingstabilityin6MKOH(C?ý50%after60cycles)

    20

    2.3Ti-NibasedalloysTi2)Multi-componentalloysTi1-xZrxNiy(x=0.2~1.0;y=0.5~1.45)??S.Wakao

    Asx?ü,?úCcharge?ü,butCdischarge?ý,becausethehydridesofZrNiandZr2Nisecondaryphasesareverystable

    Ti-Zr-Ni-M(M=V,Al,Si,??)

    Suchas(Ti0.7Zr0.2V0.1)Ni

    +V:cellvolume?ü,?ú?üCdis=350~380mAh/g;+Si:Cch=310mAh/g,butmaximumCdis=~200mAh/g 21

    2.3Ti-NibasedalloysTi-

    Thecyclinglifefor(Ti0.7Zr0.2V0.1)Nialloyelectrode

    22

    2.4Ti-MnbasedalloysTi-

    Ti-Mnbasedbinaryphasediagram

    TiMnx(x=1.5~2.0)??allLavesphasestructure

    23

    2.4Ti-MnbasedalloysTi-

    Lavesphasestructure(À?ÎÚË?Ïà,??ÍØÆËÃÜ?ÑÐÍ?á??):??AsaphaseiscomposedofAatomandBatom,andtheirradiusrA/rB=~1.225(1.05~1.68),aLavesphaesstructurecanbeformed.Therearethreetypes:

    oC14??MgZn2typestructure(h.c.p.),canbeusedasHSA??oC15??MgCu2typestructure(f.c.c.),canbeusedasHSA??oC36??MgNi2typestructure??

    24

    2.4Ti-MnbasedalloysTi1)BinaryalloysTiMnx(x=0.4~2.0)??investigatedbyT.Gamo Asx=2.0,TiMn2almostcannotabsorbHatroomtemperature;Asxdecreasesthan1.78,alloybeginstoabsorbHatR.T.;Asx=1.5,TiMn1.5alloyhasC14typeLavesphasestructureandthebestdesorptioncapacity(betterthanTiMn2).

    TiMn1.5H2.4:Pdes=3atmat0?æand5~6atmat20?æ.

    25

    2.4Ti-MnbasedalloysTi2)Multi-componentalloysTi1-xZrxMny(x=0~0.2;y=1.5~1.8,2.0)As

    x?ü,?úCabs?ü,butCdes?ýTiMn1.5-xCrx(x=0~0.2)Crcanimprovekinetics;AsingleLavesphase;Latticeparameter?ü.

    26

    2.4Ti-MnbasedalloysTiTi1-xZrxMn1.5-yMyorTi1-xZrxMn2-yMy(M=Cr,V,Fe,Cu,Ni,Mo,??)Panasonicalloys??Ti0.9Zr0.1Mn1.4V0.2Cr0.4

    Cabs=2.1wt.%at20?æ;20;Pdes=9atmat20?æ;MaximumCdes=2.09wt.%at20?æ. Benzalloys??Ti0.98Zr0.02Mn1.5V0.45Cr0.05Fe0.09

    Pabs=50atmat24?æ;Pdes=1atmat48?æ;Reversiblecapacity1.8wt.%.

    27

    2.4Ti-MnbasedalloysTi-

    P-C-TcurvesforTi-Mnbasedalloys

    28

    ?ó.Zr-basedHydrogenStorageAlloysZr-

    3.1Zr-Hsystems

    H=?C39.7kcal/mol.H2(?C166.16kJ/mol.H2);Pdes=10-8torrat25?æand10atmat1300?æ;Cmax=2.193wt.%H2;Zr(h.c.p.)?úZrH2(f.c.c.),sohydridingneedshightemperature. 29

    3.2Zr-basedbinaryalloysZrZrM2(M=V,Cr,Mn,Fe,Co,Mo,etc)Lavesalloys 30

    3.2Zr-basedbinaryalloysZr1)ZrV2:

    C15typeLavesphase(f.c.c.),a=0.744nmfivehydridesZrV2Hx(x=0~6)???Á,?Â,?Ã,?Ä,?Å?H=?C75kcal/mol.H2(?C314kJ/mol.H2)pressureplateauisveryslope

    2)ZrCr2:

    twohydridesZrCr2H3.6(C14,h.c.p.)andZrCr2H4.0(C15,f.c.c.)pressureplateauisveryslope

    3)ZrMn2:

    effectivecapacityH/AB2=3.5~3.6atnormaltemperaturepressureplateauisgood 31

    3.3Zr-basedmulti-componentalloysZrmulti-

    1)Zr1-xTixCr2Asx=0~0.2,capacityH/M=4.0~4.5Asx=0.9~1.0,capacityH/M=~3.3 2)Zr1-xTixMn2Asx=0~0.6,capacityH/M=3.6~4.0Asx=0.6~1.0,capacityH/M=0.3~3.6 32

    3.3Zr-basedmulti-componentalloysZrmulti-

    3)Zr(Cr1-xMx)2(M=Fe,Co,Ni,????)Asx?ü,?úcapacityH/M?ý

    4)Zr(Cr1-xVx)2Asx?ü,?úcapacityH/M?üAsx?ü,?úPeq?ý,|?H|?üAsx?ü,pressureplateau?ústeeper

    33

    3.4Zr-basedelectrodealloysZr-

    Zr-basedelectrodealloyscontainsNielementduetoitselectro-catalysis1)ZrNix(x=0~5)Asx?ý,chargecapacity?ü,butdischargeability?ýAsx=1.2,thealloyhasahighestdischargecapacityCmax=210mAh/g

    34

    3.4Zr-basedelectrodealloysZr2)Zr-V-Nialloys(i)Zr(V1-xNix)2(x=0.1~1.0) Asx?ü,chargecapacity?ýAsx=0.67,thealloyhasonlyasingleC15typeLavesphaseandahighes

tdischargecapacityCmax=298mAh/gat16mA/g.

    35

    3.4Zr-basedelectrodealloysZr(ii)Zr(V0.33Ni0.67)2+?Á(?Á=0~1.0)?Á As?Á?ü,chargecapacity?ýAs?Á=0.2~0.4,thealloyhasahighestdischargecapacityCmax=311mAh/g.

    36

    3.4Zr-basedelectrodealloysZr-

    (iii)Zr(V0.25Ni0.75)?Á(?Á=1.0~4.0)

    ThealloyshaveamainphaseofC15typeLavesphase.As?Á?Ü2.5,onlyasingleC15typeLavesphase;As?Á>2.0(super-stoichiomertic),V?úAside;As?Á=2.0,dischargecapacityCmax=394mAh/gat5mA/g;As?Á=3.0,dischargecapacityCmax=800mAh/gat2mA/gandCmax=400mAh/gat20mA/g. 37

    3.4Zr-basedelectrodealloysZr3)Zr-Cr-Nialloys(i)Zr(Cr1-xNix)2(x=0.15~0.65)??ZJU Asx=0.35(0.33~0.5),ahighestdischargecapacityCmax=305mAh/gat50mA/g;Asx=0.4~0.45,mainphasestructurechangesfromC15toC14

    38

    3.4Zr-basedelectrodealloysZr-

    (ii)ZrCrxNi2-x(x=0.15~0.65)??J.M.Joubert

    Asx>1.0,asingleC14Lavesphase;Asx=0.8,amainphaseofC15andasecondaryphaseofC14;Asx<0.4,amainphaseofC15andasecondaryphaseofZr7Ni10;theannealedalloys(1175?æ?Á15days)haveonlyasingleC15Lavesphase;as-castalloyCmax=331mAh/g;annealedalloyCmax=300mAh/g.

    39

    3.4Zr-basedelectrodealloysZr-

    4)Zr-Mn-NialloysgoodactivationbehaviorSuchasZr(Mn1-xNix)2(x=0.4~0.75)multi-phasestructurewithamainphaseofC15;Asx=0.55,ahighestdischargecapacityCmax=242mAh/g;Asx=0.45~0.55,thealloyshavegoodHRDandcyclinglife.

    40

    3.4Zr-basedelectrodealloysZr-

    41

    3.4Zr-basedelectrodealloysZr-

    ZrV2based

    ZrMn2based

    ZrCr2based

    42

    3.4Zr-basedelectrodealloysZr-

    5)ThefeaturesofZr-basedelectrodealloysHighcapacity(Cmax>400mAh/g)Goodcyclinglife(stablein6MKOH)Badactivationbehavior(n>10,evento70~100cycles)Badhigh-rate-dischargeability

    43

    3.4Zr-basedelectrodealloysZrResolvents:(i)alloying:

    +Mn,La:?üactivation,?üCdis+Mo:formnewsecondaryphase,?ú?ücatalysis+Fe,Co:?üdischargingefficiencyCdis/Cch

    (ii)surfacemodificationtreatment:

    HFsolution:?üactivation,?üCdisHotalkalisolution:?ücatalysisReductiontreatment 44

    TheEnd

    45

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