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Capacity retention in hydrogen storage alloysResults of our examination of the properties of several candidate materials for hydrogen storage electrodes and their relation to the decrease in H-storage capacity upon open-circuit storage over time are reported. In some of the alloy samples examined to date, only about 10 percent of the hydrogen capacity was lost upon storage for 20 days, while in others, this number was as high as 30 percent for the same period of time. This loss in capacity is attributed to two separate mechanisms: (1) hydrogen desorbed from the electrode due to pressure differences between the cell and the electrode sample; and (2) chemical and/or electrochemical degradation of the alloy electrode upon exposure to the cell environment. The former process is a direct consequence of the equilibrium dissociation pressure of the hydride alloy phase and the partial pressure of hydrogen in the hydride phase in equilibrium with that in the electrolyte environment, while the latter is related to the stability of the alloy phase in the cell environment. Comparison of the equilibrium gas-phase dissociation pressures of these alloys indicate that reversible loss of hydrogen capacity is higher in alloys with P(eqm) greater than 1 atm than in those with P(eqm) less than 1 atm.
Document ID
19930048968
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Anani, A.
(NASA Headquarters Washington, DC United States)
Visintin, A.
(NASA Headquarters Washington, DC United States)
Srinivasan, S.
(NASA Headquarters Washington, DC United States)
Appleby, A. J.
(Texas A & M Univ. College Station, United States)
Reilly, J. J.
(NASA Headquarters Washington, DC United States)
Johnson, J. R.
(Brookhaven National Lab. Upton, NY, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1992
Publication Information
Publication: In: Hydrogen storage materials, batteries, and electrochemistry; Proceedings of the Symposium, Phoenix, AZ, Oct. 14-17, 1991 (A93-32963 12-25)
Publisher: Electrochemical Society, Inc.
Subject Category
Inorganic And Physical Chemistry
Accession Number
93A32965
Funding Number(s)
CONTRACT_GRANT: NAGW-1194
Distribution Limits
Public
Copyright
Other

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