Improvement of Hydrogen Storage Alloys as a Negative Electrode in Ni-MH Battery

镍氢电池负极储氢合金的改进

基本信息

批准号：
08650819
负责人：
KAMASAKI Seiji
金额：
$ 1.02万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650819/
关键词：
Ni-MH Battery Hydrogen Storage Alloy Rare Earth Metal based Alloy Surface Analysis La(OH)_3 Whisker Ni-Co Microcrystals Long Life Electrode La(OH)_3ウイスカー Ni-MH二次電池 Ni-Co微結晶

项目摘要

Highly efficient AB_5-type Hydrogen Storage Alloys for Ni-MH Battery Ternary LaNi_<5-X>M_X hydrogen storage alloys, partially substituted Ni by Co or Al, react with the alkaline electrolyte in Ni-MH battery to form La(OH)_3 whiskers and inductively precipitate metallic Ni or Ni-Co microcrystals around the surface of the alloys. Hydrogen storage alloy electrode performances were largely dependent on the electrochemical properties of these new microcrystals.So the LaNi_<5-(a+b)>Co_aAl_b alloys were designed and synthesized accordingly to following course, determinations of (1) Al contents which induce the growth of La(OH)_3 whiskers and the precipitations of microcrystals effectively and (2) Co contents which dominate the electrochemical characteristics of alloy electrodes, and comfirmatively evaluated the electrode performances in Ni-MH battery.With increase of Al contents, the maximum discharge capacities of alloy electrodes decreased, while the capacity decays of them during charge-discharge cycles were suppressed. Moreover, electrochemically nonactive Al_2O_3 formed and dispersed on ths surface of the alloys by an excess of Al substitutions (b>0.4), and difficulties of utilization of charged hydrogens increased. On the other hand, Ni-Co microcrystals of almost same compositions as mother alloys were induced and those of composition Co/Ni*3, which have a homogeneous structure of substitutional solid solutions, were superiorly resistant to corrosion.LaNi_<3.5>Co_<1.1>Al_<0.4> alloys synthesized accordingly to the electrochemical data mentioned above were verified to be haigh capacity and long life (maximum discharge capacity : 320 Ah/kg, degradation : 0.01 Ah・kg^<-1>・cycle^<-1>).

镍氢电池用高效AB_5型储氢合金三元LaNi_<5-X>M_X储氢合金，用Co或Al部分取代Ni，与镍氢电池中的碱性电解液反应生成La(OH)_3储氢合金电极的晶须和感应沉淀金属镍或镍钴微晶的性能很大程度上取决于这些新型材料的电化学性能。因此，根据以下过程设计并合成了LaNi_<5-(a+b)>Co_aAl_b合金，确定了(1)有效诱导La(OH)_3晶须生长和微晶析出的Al含量，以及(2) Co含量对合金电极的电化学特性起主导作用，并验证性地评价了镍氢电池的电极性能。随着Al含量的增加，合金的最大放电容量此外，由于过量的Al取代(b>0.4)，在合金表面形成并分散了电化学惰性的Al_2O_3(b>0.4)，充氢的利用变得困难。另一方面，诱导出与母合金成分几乎相同的Ni-Co微晶以及具有均匀替代结构的Co/Ni*3成分的微晶。根据上述电化学数据合成的LaNi_<3.5>Co_<1.1>Al_<0.4>合金经验证具有高容量和长寿命（最大放电容量：320 Ah/kg，退化：0.01 Ah・kg^<-1>・周期^<-1>）。