Use of Ni/CNT Particles as Additive Fillers in Ebonite Bipolar Plates for Proton-Exchange Membrane Fuel Cells.

Abstract

Composite-based bipolar plates are a chance to substitute graphite and metal bipolar plates because of their corrosion resistance and better chemical and mechanical properties, but they still have various electrical conductivity properties. One of the problems is the loading of filler that depends on matrix types which will affect the electrical conductivity of bipolar plates; ebonite has potential as a matrix in composite bipolar plates because it is obtained from elastomer or rubber. In this work, nickel and carbon nanotubes (CNT) that have a high electrical conductivity will be investigated as additive fillers on graphite particles to enhance the electrical conductivity of ebonite bipolar plates. The formulation and characterization of ebonite bipolar plates with graphite and graphite Ni/CNT and their various contents are the main objectives of this research. Characterization by scanning electron microscopy (SEM) for identification and morphology of compounds and ebonite bipolar plates and Raman spectroscopy for identification of the type carbon in Ni/CNT was performed. Some tests such as bending/flexural tests, corrosion tests, and resistance testing for interfacial contact resistance were conducted to study the properties and optimum of the composite materials. In this research, Ni/CNT particles were added as additive fillers with graphite to enhance the electrical conductivity of fillers in ebonite bipolar plates of proton-exchange membrane fuel cells and their impacts were studied. By through-plane testing, graphite fillers were added in ebonite bipolar plates with 65-75% w/w content, achieving electrical conductivity values from 22.3 to 34 S/cm. This is still below the technical target set by the US DOE for composite bipolar plates. But by adding 30% Ni/CNT filler contents in ebonite bipolar plates at various filler contents from 65% to 75% w/w, one can achieve electrical conductivities from 104.35 to 165.52 S/cm. Only 65% w/w filler with 30% Ni/CNT can meet the technical targets such as a bending/flexural test value of 25.58 N/mm2, a corrosion test value of 0.894 μA/cm2 (I corr), and an interfacial contact resistance value of 3.09 mΩ cm2. Further improvements are needed based on fuel cell applications, as indicated by some additional data that did not meet technical targets.