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Tomography based screening of flow field / current collector combinations for PEM water electrolysis

 
: Zielke, L.; Fallisch, A.; Paust, N.; Zengerle, R.; Thiele, S.

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RSC Advances 4 (2014), No.102, pp.58888-58894
ISSN: 2046-2069
English
Journal Article
Fraunhofer ISE ()
Energietechnik; Wasserstoff- und Brennstoffzellentechnologie; Wasserstofferzeugung durch Wasserelektrolyse; Elektrolyse; Tomografie

Abstract
Current collectors in PEM water electrolysis perform several functions that influence overall performance. These include conducting heat and electrons, as well as transporting water and gas. X-ray tomography, standardized reconstruction, and calculation methods are used to compare the morphological and transport parameters of eight different current collectors functioning as flow fields for PEM water electrolysis. We find simple exponential relations between through-plane thermal conductivity λ and porosity p (λ20°C(p) = 1749p−1.306 − 4.420), as well as between through-plane electrical conductivity σ and water permeability K (σ(K) = 10−6 × K−0.6376). In addition, we use both local and global concepts to investigate the pore space of current collectors. We hereby investigate homogeneity and characteristic sizes, like mean pore diameter or mean distance between solid parts at the catalytic interface. Moreover, we find that the local concept of mean chord lengths can be used to explain electrical and thermal conductivity anisotropies. These chords can be used to predict the direction of the largest conductivity for fibrous current collectors.

: http://publica.fraunhofer.de/documents/N-324144.html