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Development of carbon nanotube based bipolar plates for vanadium redox flow batteries

: Caglar, B.

Beckwith, S.W. ; Society for the Advancement of Material and Process Engineering -SAMPE-:
Navigating the global landscape for the new composites. SAMPE Tech conference and exhibition. CD-ROM : October 22 - 25, 2012, North Charleston, South Carolina
Covina, Calif.: SAMPE, 2012
ISBN: 978-1-934551-13-4
13 S.
Society for the Advancement of Material and Process Engineering (SAMPE Tech conference and exhibition) <2012, North Charleston/SC>
Fraunhofer ICT ()

Polypropylene (PP), graphite and carbon nanotubes (CNTs) based composites were processed with a co-rotating twin-screw extruder and bipolar plates were produced via injection molding. Two different types of PP were chosen according to their melt flow rates (MFR 8 and 800). In order to understand the influence and the synergistic effect of fillers, graphite content was fixed to 70 weight (wt.) % and flake (with particle sizes < 30 m, > 100 m) and spherical (<3 0 m) type graphite were processed as single fillers and mixtures of them. Two different CNT-loadings (1.5 wt.% and 3 wt.%) were used as secondary fillers. Flexural strength tests and in-plane as well as through-plane electrical conductivity measurements were carried out. As primary filler, flake type graphite particles were found to be superior to spherical ones. With decreasing particle size, electrical conductivity increased but processing became more difficult. As secondary filler; CNTs increased through-plane e lectrical conductivity from 3.1 S/m to 80.5 S/m and in-plane conductivity from 105 S/m to 1145 S/m by connecting graphite particles more efficiently, exhibiting low impact to flexural strength. PP with MFR 800 showed better flexural strength and higher increase in electrical conductivity than PP with MFR 8 by addition of CNTs. Corrosion behaviors of bipolar plates were examined and their cell performances were tested in laboratory scale vanadium redox flow battery.