Hybrid conductive filler/polycarbonate composites with enhanced electrical and thermal conductivities for bipolar plate applications

Abstract

Conductive polymer composites (CPCs) with high electrical and thermal conductivities are demanded for bipolar plates of fuel cells. In this work, CPCs of polycarbonate (PC) filled with carbon nanotube (CNT), carbon fiber (CF), graphite (G), and their double and triple hybrids were prepared using solution casting method followed by compression molding. The results showed that the electrical percolation thresholds for the PC‐CNT and PC‐CF were ~1 wt% and ~10 wt%, respectively, while no clear threshold was found for PC‐G composites. Addition of 3–5 wt% CNT improved the electrical conductivity of PC‐CF and PC‐G systems up to 6 orders of magnitude and enhanced the thermal conductivity as much as 65%. The results of triple hybrid CPCs (with constant loading of 63 wt%) indicated that the combination of highest electrical and thermal conductivities is achieved when the CF and CNT loadings were near their percolation thresholds. Therefore, a triple filler system of 3 wt% CNT, 10 wt% CF, and 50 wt% G resulted in a composite with the through‐plane and in‐plane electrical conductivity, and thermal conductivity values of 12.8 S/cm, 8.3 S/cm, and 1.7 W/m•K, respectively. The results offer a combination of properties surpassing the existing values and suitable for high‐conductivity applications such as bipolar plates. POLYM. COMPOS., 40:3189–3198, 2019. © 2018 Society of Plastics Engineers

Direction Dependent Electrical Conductivity of Polymer/Carbon Filler Composites

“…In such cases, both in- and through-plane conductivity are required. On the other hand, CPC based bipolar plates used in fuel cells have to possess high through-plane conductivity, which is related to the electron flow direction in an operating fuel cell [14,15,16]. Moreover, when using CPCs as adhesives to join different conductive parts, through-plane conductivity is a requirement to achieve conductive joined parts.…”

Thermal Conductivity and Electrical Resistivity of Melt-Mixed Polypropylene Composites Containing Mixtures of Carbon-Based Fillers

“…In contrast, the thermal conductivity requires phonon transport between neighboring thermal conductive fillers. Thus, the trends in the development of electrical properties and thermal conductivity with filler content are very different for polymer composites [9,10,11,12,13,14,15,16,17,18,19,20,21].…”

“…Such synergistic effects have been successfully demonstrated for the electrical conductivity of epoxy [38,39] and thermoplastic polymers [40,41,42,43,44] filled with carbon nanotubes and carbon black. Naji et al [19] described for polycarbonate (PC) composites that CNT can act as a bridge between larger fillers, such as carbon fibers and graphite, and fill the gaps to form a more effective conductive network. There are only a few papers that consider the electrical and thermal conductivity of polymer nanocomposites together [11,13,17,19,21].…”

“…Naji et al [19] described for polycarbonate (PC) composites that CNT can act as a bridge between larger fillers, such as carbon fibers and graphite, and fill the gaps to form a more effective conductive network. There are only a few papers that consider the electrical and thermal conductivity of polymer nanocomposites together [11,13,17,19,21].…”

Evaluating Current Distribution and Influence of Defect Sites for Graphitic Compound Bipolar Plate Materials

“…Even though there are many studies on the measurement of through‐plane and in‐plane conductivity , they are only studies determining these values as a global parameter. To the best of our knowledge, there are no reports on experimental evaluation of in‐plane current distribution in graphitic materials.…”