Conductive materials for polymeric bipolar plates: Electrical, thermal and mechanical properties of polyethylene-carbon black/graphite/magnetite blends

Abstract

The elimination of corrosion, reduction of mass and the improvement of mechanical, electrical and thermal conductivity properties are the main aims to progress bipolar plate technology for polymer electrolyte membrane fuel cells. In addition, the large numbers of bipolar plates required in automotive fuel cell stacks (on the order of 400 plates per vehicle) will demand mass production to meet future demands as well as reduce costs through cheap production processes. Highly conductive, low density, low cost and corrosion-resistant materials that can be utilised in production processes such as injection and compression moulding are ideal candidates for bipolar plates. Carbon black, graphite, magnetite with polyethylene composites were made and tested for their electrical and thermal conductivities and mechanical properties and compared to the US Department of Energy targets for 2015. The carbon black composites exhibited better electrical conductivity than the other fillers where at 65 wt% the conductivity was $24 S/cm for through-plane conductivity and had a flexural strength of $32 MPa. Injection moulding produced composites with more material stability and greater mechanical strength than compression mouldings although compression mouldings produced composites with higher thermal conductivities where graphite displayed the highest thermal conductivity of $2 W/mK. Although well short of the US Department of Energy targets these materials show promise.

Material property models for polyethylene-based conductive blends suitable for PEM fuel cell bipolar plates

“…A spherical mono-dispersed filler phase is assumed for all models due to the spherical particle shape of the carbon filler and the boulder-like graphite and magnetite filler shapes coupled with the random orientation observed from both magnetite and graphite micrographs presented previously. 1 …”

“…For the carbon black compression moulded samples, it is unclear as to whether the data would have deviated further from the model due to the limited number of data points resulting from processing problems. 1 The model may not account for differences in test speed and processing, slow test speeds could transfer greater loads to the specimen before fracture resulting in greater modulus than the model predicts and processing variations within and between injection and compression moulding may generate similar increases in modulus compared to the model.…”

“…Electrical and thermal conductivity and the tensile and flexural strength results of high density polyethylene (HDPE) blends with carbon black, graphite and magnetite fillers presented in a previous study 1 have been used here to assess and validate models used to predict such properties.…”

Developing a nested micromechanical model to predict the relaxation moduli of graphene nanoplatelets/carbon fiber reinforced hybrid nanocomposites

“…Graphene has high Young's modulus ($1 TPa) whose fracture strength is about 125 GPa. 9,10 Therefore, different graphene materials have been used as reinforcement in polymer matrixes as a promising component. 11 By exfoliating graphite and graphene oxide, graphene nanoplatelets (GNPs) are constructed.…”

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.…”