Description: Observing proton motion on the nanoscale in polymeric electrolyte membranes with quasielastic neutron scattering

This title appears in the Scientific Report : 2014

Observing proton motion on the nanoscale in polymeric electrolyte membranes with quasielastic neutron scattering

The mechanism of proton conductivity in high temperature polymer electrolyte fuel cells (HT-PEFCs) has been investigated with macroscopic conductivity measurements and on a microscopic scale with quasielastic neutron scattering techniques. Polybenzimidazole membranes, which are used in HT-PEFCs, are...

Personal Name(s):	Holderer, O. (Corresponding Author)
	Ivanova, O. / Hopfenmüller, B. / Zamponi, M. / Maier, W. / Majerus, Anne / Lehnert, W. / Monkenbusch, M. / Zorn, R.
Contributing Institute:	Neutronenstreuung; JCNS-1 Neutronenstreuung; ICS-1 JCNS-FRM-II; JCNS-FRM-II Technoökonomische Systemanalyse; IEK-3
Published in:	International journal of hydrogen energy, 39 (2014) 36, S. 21657–21662
Imprint:	New York, NY [u.a.] Elsevier 2014
DOI:	10.1016/j.ijhydene.2014.09.018
Document Type:	Journal Article
Research Program:	Soft Matter Composites JCNS
Subject (ZB):	Energy > 0 Materials Science > 0 Soft Condensed Matter > 1
	Publikationsportal JuSER

Please use the identifier: http://dx.doi.org/10.1016/j.ijhydene.2014.09.018 in citations.

The mechanism of proton conductivity in high temperature polymer electrolyte fuel cells (HT-PEFCs) has been investigated with macroscopic conductivity measurements and on a microscopic scale with quasielastic neutron scattering techniques. Polybenzimidazole membranes, which are used in HT-PEFCs, are doped with phosphoric acid (PA) to achieve the desired proton conductivity. Neutron spin echo experiments showed that the polymer matrix is very rigid incoherent scattering experiments, but incoherent scattering revealed rather fast diffusion processes, compatible with macroscopic conductivity measurements. The measured diffusion is faster than anticipated from the conductivity of a phosphoric acid doped PBI membrane, but slower than that expected for pure phosphoric acid. Over larger distances the fractal polymer membrane network slows down the locally fast diffusion to the macroscopic values. With elastic fixed window scans on a backscattering spectrometer an activation energy of 7.6 kJ/mol is obtained at typical conditions in an HT-PEFC.