Journal Article

FZJ-2018-03334

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Determination of Anion Transference Number and Phosphoric Acid Diffusion Coefficient in High Temperature Polymer Eelctrolyte Membranes

Becker, H. ; Reimer, U. (Corresponding author)FZJ* ; Aili, D. ; Cleemann, L. N. ; Jensen, J. O. ; Lehnert, W.FZJ*RWTH* ; Li, Q. (Corresponding author)

2018
Electrochemical Soc. Pennington, NJ

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Please use a persistent id in citations: http://hdl.handle.net/2128/21191  doi:10.1149/2.1201810jes

Abstract: The passage of an electrical current through phosphoric acid doped polymer membranes involves parasitic migration of the acid, which imposes a critical issue for long-term operation of the high temperature polymer electrolyte membranes fuel cell (HT-PEMFC). To elucidate the phenomenon, a three-layered membrane is constructed with embedded micro reference electrodes to measure phosphoric acid redistribution in a polybenzimidazole based membrane. Under a constant load, a concentration gradient develops due to the acid migration, which drives the back diffusion of the acid and eventually reaches a steady state between migration and diffusion. The acid gradient is measured as a difference in local ohmic resistances of the anode- and cathode-layer membranes by electrochemical impedance spectroscopy. The phosphoric acid diffusion coefficient through the acid doped membrane is about 10−11 m2 s−1, at least one order of magnitude lower than that of aqueous phosphoric acid solutions. The anion (H2PO4−) transference number is found to range up to 4% depending on current density, temperature and atmospheric humidity of the cell, implying that careful control of the operating parameters is needed in order to suppress the vehicular proton conduction as a degradation mitigation strategy.

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Contributing Institute(s):

1. Technoökonomische Systemanalyse (IEK-3)
2. Elektrochemische Verfahrenstechnik (IEK-14)

Research Program(s):

1. 135 - Fuel Cells (POF3-135) (POF3-135)

Appears in the scientific report 2018

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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