1998 Fiscal Year Final Research Report Summary
Designing and Surface Modification of Hydrogen Strage Alloy Material
| Project/Area Number |
09650913
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
工業物理化学
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| Research Institution | Ritsumeikan University |
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Principal Investigator |
MATSUOKA Masao Ritsumeikan Chemistry, Professor, 理工学部, 教授 (10081340)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Nickel-hydride battery / Hydrogen storage alloy / Laves-phase alloy / Mg-Ni system alloy / Ca-Ni system alloy / Ti-Ni system alloy |
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| Research Abstract |
Extensive research on hydrogen storage alloys as a negative electrode material has been carried out, because of the cleanness and high energy density of nickel-hydride battery. The possibility of various alloy designings is one of the feature of hydrogen storage alloy. Such Laves-phase alloys, Mg-Ni system and Ca-Ni system alloys are attractive as a material for the next generation because the energy density is expected to be larger than that of currently used hydrogen storage alloys based on rare earth system. In this study, charge and discharge characteristics ofnegative electrode consisting of more promising hydrogen storage alloys prepared by high frequency melting and mechanical grinding were evaluated, The results are summarized as follows.
1)The surface modification of AB_2-type Laves-phase Alloy (A=Zr_<09>Ti_<01>, B=Ni_<055>Co_<0.05>Mn_<0.25>V_<0.1>Cr_<0.05>) with 10 mol/dm^3 KOH solution at boiling temperature for 1h remarkably improved the initial
surface activity leading to the first discharge capacity of ca. 400 mAh g^<-1>. Fragmentation of the alloy particles by mechanical grinding also contributed to an increase in high-rate dischargeability.
2)The discharge capacities of mechanically alloyed MgNi and Ca_2Ni particles were found to be 500 mAh g^<-1> and 200 mAh g^<-1>, respectively. It was confirmed that MgO powder accelerated the process of mechanical alloying, but graphite powder strongly inhibited the alloying of MgNi.
3)The discharge capacity of mechanically alloyed Ti_2Ni negative electrode was found to be l70mAh g_2. The discharge capacity of the alloy increased to 340 mAh g_2 by heat-treatment at 500ﾟC for lh. The combination of mechanical alloying and low-temperature annealing was found to be promising method for hydrogen storage alloy used for the negative electrode material.
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