Journal Article

FZJ-2020-05413

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Phosphoric Acid Dynamics in High Temperature Polymer Electrolyte Membranes

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

2020
IOP Publishing Bristol

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Please use a persistent id in citations: http://hdl.handle.net/2128/26826  doi:10.1149/1945-7111/abb70c

Abstract: Phosphoric acid is amphoteric and has been used to dope basic polymer, e.g. polybenzimidazole, membranes and acidic polymer, e.g. perfluorosulfonic acid, membranes. Both membrane systems exhibit high proton conductivities at temperatures above 100 °C under anhydrous conditions. The former has been developed into a commercial fuel cell technology while the latter can only deliver a few mA cm−2 in fuel cells and hydrogen pumping cells. In this work, it is experimentally verified that the current window of acid doped perfluorosulfonic acid membranes in electrochemical cells under dry conditions is limited by the migration of H4PO4+ species in combination with the slow H3PO4 diffusion. The phosphoric acid dynamics were monitored in a cell equipped with integrated reference electrodes in the electrolyte membrane, which allowed for quantification of the phosphoric acid in different membrane segments. From the time-resolved measurements, the H4PO4+ transference number was found to be as high as 52% under dry conditions. In combination with the slow H3PO4 back-diffusion, which was 5–6 orders of magnitude lower than that of water, the migration of H4PO4+ towards the cathode results in rapid resistance increase at the anode-membrane interface, ultimately leading to the cell failure.

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Contributing Institute(s):

1. Elektrochemische Verfahrenstechnik (IEK-14)

Research Program(s):

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

Appears in the scientific report 2020

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

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