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Hydrogen Storage for Micro-fabricated Electrochemical Devices

Shan, Xi
http://rave.ohiolink.edu/etdc/view?acc_num=case1089864469

Abstract Details

2004, Doctor of Philosophy, Case Western Reserve University, Materials Science and Engineering.
Micro-fabricated PEM fuel cells and other micro-power systems are being developed to provide on-board electrical power source for MEMS systems. The development of these micro-power systems needs a hydrogen source that has high volume density, fast hydriding/de-hydriding kinetics and can be easily activated under atmosphere pressure at room temperature. In this investigation, the effects of palladium on the hydrogen storage properties of LaNi4.7Al0.3, CaNi5 and Mg2.4Ni were studied. It is found that mechanical grinding these alloys with palladium can lower the activation pressures to sub-atmosphere at room temperature and significantly increase hydriding/de-hydriding kinetics; the activation durability of these alloys in air is also greatly extended to more than 2 years. The hydride ink making process, in which polymer binders are added to the 10wt% palladium modified alloy, slightly decreases the storage capacity, but the alloy is still active under atmospheric pressure at room temperature. The cyclic hydriding/dehydriding stabilities of palladium modified alloys under pure and humidified hydrogen were studied. After 5000 cycles under pure hydrogen, the storage capacities of 10wt% palladium modified LaNi4.7Al0.3 and CaNi5 decrease 14-20% and 30-35% respectively. For test under hydrogen with 75% relative humidity, the storage capacity of 10wt% palladium modified LaNi4.7Al0.3 decreases 60% after 3000 cycles. The degradation of LaNi4.7Al0.3 is mainly due to the oxidation caused by air exposures during the test or water vapor in the hydrogen; for CaNi5, disproportionation of CaNi5 is the main reason. The mechanism of palladium on the activation and hydriding/de-hydriding of the alloys can be explained by hydrogen spillover and reverse hydrogen spillover. When inks made with 10wt% palladium modified LaNi4.7Al0.3 and CaNi5 were used as the hydrogen source for PEM fuel cell, the maximum currents they can provide exceed the requirement for the micro-fabricated PEM fuel cell system, the electric energy capacities of the LaNi4.7Al0.3 and CaNi5 are 120Wh/kg and 110Wh/kg respectively. The efficiency of hydrogen from LaNi4.7Al0.3 is more than 90%, while for CaNi5 the efficiency is only 60% due to its low de-hydriding plateau pressure
Joe Payer (Advisor)
Engineering, Materials Science
hydrogen storage; fuel cell; spill over

Recommended Citations

Citations

  • Shan, X. (2004). Hydrogen Storage for Micro-fabricated Electrochemical Devices [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1089864469

    APA Style (7th edition)

  • Shan, Xi. Hydrogen Storage for Micro-fabricated Electrochemical Devices. 2004. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1089864469.

    MLA Style (8th edition)

  • Shan, Xi. "Hydrogen Storage for Micro-fabricated Electrochemical Devices." Doctoral dissertation, Case Western Reserve University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1089864469

    Chicago Manual of Style (17th edition)

case1089864469
1,551
© 2004, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.