Development and characterization of expanded graphite-based nanocomposite as bipolar plate for polymer electrolyte membrane fuel cells (PEMFCs)

Expanded graphite-based nanocomposites as bipolar plates for polymer electrolyte membrane fuel cells (PEMFCs) are developed by compression molding technique. The expanded graphite is prepared by chemical intercalation of 50 BS mesh particle size of natural graphite by strong acid. It is found that composite bipolar plate with a varying weight percent of resin and EG gives the high electrical conductivity, competitive mechanical properties with a bulk density of 1.5-1.55 g/cm(-3), and air tightness. The EG-based composites with 40-45 wt % of resin are suitable for achieving desired properties of the bipolar plate as per the DOE advanced series target. The addition of 5 wt % of carbon black is helpful for improving the electrical conductivity without compromising other properties of the bipolar plate. The lower value of the modulus of expanded graphite (3-8 GPa) composite as compared to graphite-resin-based composite (> 12 GPa) plates attributes that these plates are more flexible and able to withstand shock and vibration during mobile operation of the fuel cell stack.