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(abstract) Experimental and Modeling Studies of the Exchange Current at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase BoundaryThe microscopic mechanism of the alkali ion-electron recombination reaction at the three phase boundary zone formed by a porous metal electrode in the alkali vapor on the surface of an alkali beta'-alumina solid electrolyte (BASE) ceramic has been studied by comparison of the expected rates for the three simplest reaction mechanisms with known temperature dependent rate data; and the physical parameters of typical porous metal electrode/BASE/alkali metal vapor reaction zones. The three simplest reactions are tunneling of electrons from the alkali coated electrode to a surface bound alkali metal ion; emission of an electron from the electrode with subsequent capture by a surface bound alkali metal ion; and thermal emission of an alkali cation from the BASE and its capture on the porous metal electrode surface where it may recombine with an electron. Only the first reaction adequately accounts for both the high observed rate and its temperature dependence. New results include crude modeling of simple, one step, three phase, solid/solid/gas electrochemical reaction.
Document ID
Document Type
Preprint (Draft being sent to journal)
External Source(s)
Williams, R. M.
Jeffries-Nakamura, B.
Ryan, M. A.
Underwood, M. L.
O'Connor, D.
Kikkert, S.
Date Acquired
August 23, 2013
Publication Date
May 15, 1993
Distribution Limits
electrochemical reactions exchange current electrolyte thermal-to-electric
alkali ion-electron recombination reaction porous metal electrode