Journal Article

FZJ-2019-00718

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Using neutron methods SANS and PGAA to study evolution of structure and composition of Alkali-doped Polybenzimidazole membranes

Babcock, E. (Corresponding author)FZJ* ; Szekely, N. ; Konovalova, A.Extern* ; Lin, Y.FZJ* ; Appavou, M.-S.FZJ* ; Mangiapia, G. ; Revay, Z.MLZ* ; Stieghorst, C.MLZ* ; Holderer, O.FZJ* ; Henkensmeier, D. ; Lehnert, W.FZJ* ; Carmo, M.FZJ*

2019
Elsevier New York, NY [u.a.]

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Please use a persistent id in citations: http://hdl.handle.net/2128/21546  doi:10.1016/j.memsci.2019.01.026

Abstract: Potassium hydroxide (KOH) doped polybenzimidazole (PBI) membranes are investigated as compelling candidates for water electrolysis applications, drastically reducing the ohmic losses in contrast to thick ZrO2 based diaphragms. Using small angle neutron scattering (SANS) we have found that the structure of the (KOH doped) PBI changes with doping time on a minute time scale, and that the development of the structure is highly dependent on the KOH concentration. This data is correlated with macroscopic measurements of membrane swelling resulting from the doping process which also occurs on a minute time scale. Then, using prompt gamma activation analysis (PGAA) to follow the changes in time of the chemical composition, we have found that the K concentration of these samples only increases slightly with doping times after a very rapid initial uptake, reaching a saturation value that is relatively independent of KOH concentration for long doping times of up to 24 h. However measurements of similarly doped samples show increases in ion-conductivity of nearly 3 fold, and resistivity reductions of over 2 fold on the same time scales. These measurements prove that PGAA is a sensitive method to follow changes in the chemical compositions during doping, while SANS can give information on the sub-micro structural changes of polymer electrolyte membranes. Since these methods can be correlated with ex-situ measurements of composition, resistance, ion-conductivity and macro-structure, the combined use of PGAA and SANS provides a promising means for in-operando study in order to elucidate changes in membrane performance due to electrochemical cycling, as well as to help characterize and optimize doping parameters though in-situ doping measurements, by enabling real-time study of such membrane systems.

Keyword(s): Energy (1st) ; Materials Science (2nd) ; Soft Condensed Matter (2nd)

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Contributing Institute(s):

1. JCNS-FRM-II (JCNS-FRM-II)
2. Elektrochemische Verfahrenstechnik (IEK-3)
3. Streumethoden (JCNS-2)
4. Heinz Maier-Leibnitz Zentrum (MLZ)
5. Neutronenstreuung (Neutronenstreuung ; JCNS-1)

Research Program(s):

1. 144 - Controlling Collective States (POF3-144) (POF3-144)
2. 6213 - Materials and Processes for Energy and Transport Technologies (POF3-621) (POF3-621)
3. 6215 - Soft Matter, Health and Life Sciences (POF3-621) (POF3-621)
4. 6G15 - FRM II / MLZ (POF3-6G15) (POF3-6G15)
5. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)

Experiment(s):

1. PGAA: Prompt gamma activation analysis (NL4b)
2. KWS-2: Small angle scattering diffractometer (NL3ao)

Appears in the scientific report 2019

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

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