Poly(phenylene sulfide) Graphite Composites with Graphite Nanoplatelets as a Secondary Filler for Bipolar Plates in Fuel
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Article www.springer.com/13233 pISSN 1598-5032 eISSN 2092-7673
Poly(phenylene sulfide) Graphite Composites with Graphite Nanoplatelets as a Secondary Filler for Bipolar Plates in Fuel Cell Applications Sang-Ha Kim1 Jong Seok Woo2 Soo-Young Park*,1
1
Department of Polymer Science & Engineering, Polymeric Nanomaterials Laboratory, School of Applied Chemical Engineering, Kyungpook University, 80 Daehak-ro, Buk-gu, Daegu 41566, Korea 2 Advanced Center of Engineering, Morgan Advanced Materials, 23, Dalseong2cha 4-ro, Guji-myeon, Dalseong-gun, Daegu 43013, Korea Received March 17, 2020 / Revised June 22, 2020 / Accepted July 1, 2020
Abstract: Graphite nanoplatelets (GNPs) have been used as a secondary filler to improve the electrical conductivity of poly(phenylene sulfide) (PPS)/graphite composites for use as bipolar plates in fuel cells, and the effects of adding small quantities of GNPs on the electrical, thermal, and mechanical properties of PPS/GNP/graphite composites have been extensively studied. The GNPs were compounded with PPS to produce master batch (MB) chips that were further ground to fine MB powder (MBg). PPS/MBg/graphite powders were compressed to fabricate 10-mm thick square samples. Composites containing a large quantity of graphite (~80 wt%) were then tested for use as a bipolar plate in phosphoric acid fuel cells. When 5 wt% GNP was added to the PPS/graphite composite, the in-plane electrical conductivity increased almost twofold from 643 to 1340 S·cm-1, the through-plane electrical conductivity increased from 19 to 54 S·cm-1, the through-plane thermal conductivity increased approximately two-fold from 60 to 129 W·(mK)-1, and the flexural strength decreased slightly from 32 to 26 MPa. The fractured surface of the compressed MBg sample revealed well-dispersed GNPs in the PPS matrix, which created electrical pathways and improved the electrical conductivity of the non-conducting PPS matrix material. Thus, the PPS/GNP/graphite composite is a promising system for bipolar plate applications because a higher amount of graphite (~93 wt%) is needed in PPS/graphite composites to reach the same level of electrical conductivity as the PPS/MBg (5 wt%)/graphite (75 wt%) composite, and such a large quantity of graphite is difficult to process and leads to weaker mechanical properties. Keywords: graphite, composite, graphite nanoplate, poly(phenylene sulfide), bipolar plate, phosphoric acid fuel cell.
1. Introduction In recent years, an increasing number of fuel cell designs have been applied to a range of modern technological devices. Phosphoric acid fuel cells (PAFCs) in particular have attracted significant interest as promising power sources because they are stable and able to run for more than 10 years.1-3 One of the most important components of a PAFC is the bipolar plate (BP), which accounts for 60%-80% of its total weight and 30%-40% of its total cost.4 Metal-based BPs fabricated from stainless steel, aluminum, and titanium exhibit excellent electrical conductivity and high mechanical strength, but they
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