Y-Mg摻雜AB-,5-型貯氫電極合金的結構與電化學性能研究.pdf

1、南京理工大學碩士學位論文YMg摻雜AB型貯氫電極合金的結構與電化學性能研究姓名：李瑋申請學位級別：碩士專業(yè)：材料學指導教師：杜宇雷20090627Abstract碩t論文AbstractThehi曲一powernickel／metal—hydride(Ni／MH)batteries，whichcanbeusedonelectricvehicles，haveattractedalotofattentioninrecentyearsHowe

2、vertheworkingtemperatureofthebatteriesis80highthattheelectrochemicalpropertiesofthecommercializedABstypehydrogenstoragealloysusedasthenegativeelectrodeinthebatterieswilldeteriorateseriouslyTherefore，howtoimprovethehighte

3、mperatureelectrochemicalpropertieshasactualsignificanceindevelopingthehigh—powertypeNi／MHbaReryThus，inthisthesis，theeffectsofYorMgsubstitutionforLainABstypehydrogenstoragealloyswerestudiedInadditiontotheexperimentalwork，

4、theelectronicstructuresofLaNi5andLao$75Yo12sNiswerealsostudiedbyfirstprinciplescalculationsThemaincontentsandconclusionsareasfollowing：(1)ItisfoundthattheLalxYxNi3ssMno4A103Coo75(x=0，005，01，O2)alloysshowsinglephaseCaCust

5、ypestructureafterLaispartiallysubstitutedbyYHowever，increasingthecontentofYleadstothereductioninthelatticeparametersandcellvolumeWhenxequalsO1，boththeascastandasannealedalloyswerefoundtoexhibitthebestoverallelectrochemic

6、alpropertiesincludingthemaximumdischargecapacity(asannealed：3363mAh／gat298K3134mAh／gat333K；as—cast：3012mAh／gat298K2632mAh／gat333K)，cyclingstability(asannealed：9215％afternearly100cycles)andhighratedischargeabilityat298and

7、333K(2)ItisfoundthattheLalxMgxNi3ssMno4Alo3Coo75(x=O，005，01，02)alloysshowmultiplephases，consistingofLaNis，MgNi2andLaNi3afterLaWaspartiallysubstitutedbyMgWhenXequals005，theascastalloyshowesthebestoverallelectrochemicalpro

8、pertiesincludingthemaximumdischargecapacity(3064mAh／gat298K；2473mAh／gat333K)andcyclingstability(829％after97cyclesat298K89％after97cycles)Afterannealingalthoughthecyclingstabilityofalloys(x=O05，01，O2)wasimproved，thedischar

9、gecapacitydeducedheavilynotonlyat298KbutalsoathightemperaturewhichWasduetothechangesofphaseabundanceandtheunsuitableannealingmethodes(3)mfirstprinciplecalculationsontheelectronicstructuresofLaNisandLao$7sY0125Niswerestud

10、iedbyusingtheWIEN2KcodeItisobviouslythatthelatticeparametersandcellvolumereducedandtheFermienergydroppedslightlyafterLaWaSpartiallysubstitutedbyYAlso，thedensitiesofstatesatFermilevelofLao875Yo12sNisislowerthanthatofLaNis