资源描述：
《mh%2fni电池失效原因的分析》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、摘要为开发高容量、高功率、长寿命的MH/Ni电池，人们对它失效原因从诸多方面进行了广泛的研究，本文对此进行了较详细的综述。!本文从以下几个方面对MH/N‘电池失效原因进行了研究:(1)内压与循环寿命的关系;(2)X一射线衍射分析电池失效前后贮氢合金的晶型变化;(3)电镜扫描和表面能谱分析电池失效前后贮氢合金的表面特征(4)微极化曲线法测定电池失效前后负极的io;(5)恒电位极化法测定电池失效前后负极的D0;(6)循环伏安法测定电池失效前后正极Ni(OH):电化学反应的特征电位。厂通过以上分析测试比较可得出MH/Ni电池失效的原因:对负
2、极而言，负极活性物质的氧化一粉化、贮氢合金中活泼元素(Al,Mn,La等)的偏析腐蚀和某些贮氢合金发生晶型变化。贮氢合金的粉化加速了自身的氧化。由于氧化，贮氢合金电极的电化学容量和电化学参数(10,Do)均下降。对正极而言，主要是活性物质晶体结构发生变化，改变了电化学反应的氧化还原电位，导致正极过早地析出氧气，使充电效率降低。正极析出的氧气，一方面加剧了负极活性物质的氧化;另一方面，导致内压上升，电解液泄漏，造成电池早期失效。MH/Ni电池失效的根本原因在于正极析氧未能及时在负极发生复合反应使得贮氢合金被氧化，电池充放低。关键词MH/
3、Ni电池〔失效)正极负极氧化粉化晶体结构ABSTRACTThereasonsoffailureforMH/Nibaterieswereresearchedextensivelyfromvariousaspects,andwerepresentedindetailinthispaper.TofindoutthereasonsoffailureforMH/Nibateries,theexperimentsweredesignedasfollows:Irelationbetweeninnerpressureandcyclelife;IIX-
4、raydiffractionandcrystallinestructure;IIIScanelectronmicroscopyandX-rayphotoelectronspectroscopy;Nthelinearpolarizationexperimentsofnegativeelectrode;Vconstantpotentialpolarizationexperimentsofnegative;VIcyclicvoltammeterexperimentsofpositiveelectrode.Theexperimentalres
5、ultsshowthatthereasonsoffailureforMH/Nibaterieshavesomethingtodowithnegativeelectrodeaswellaspositiveelectrode.Fornegativeelectrode,hydrogenstoragealloyisoxidizedandpulverized,theactiveelementsinalloysuchasAl,MnandLaaresegregated,andcrystallinestructureischanged.Owingto
6、pulverization,hydrogenstoragealloyisoxidizedfurther,whichresultsinthedecreaseofcapacitiesandproperties(exchangecurrentdensityanddiffusioncoeficient).Forpositiveelectrode,thereasonsaremainlychangesofcrystalstructure,whichresultsinincreaseoftheoxidationpotentialandcloseto
7、theoxygenevolutionpotential,sochargingeficiencydecreases.Furthermore,theevolutionofoxygenpromotesoxidationofhydrogenstoragealloy,andresultsinincreaseofinnerpressureandlossoftheelectrolytesolutioninseparator,whichcausesanearlierfailureforMH/Nibateries.So,thesubstantialre
8、asonsoffailureforMH/Nibatteriesarethattheoxygenevolvedinpositiveelectrodeisnotreducedinnegativeelectrodeintime
