Study on the effects of nano-copper addition on the properties of epoxy resin/graphite composite bipolar plates

Abstract

Bipolar plates (BPs) are vital components in Proton Exchange Membrane Fuel Cells (PEMFCs), and their performance and cost significantly impact fuel cell stack efficiency and affordability. BPs require excellent conductivity, strength, and corrosion resistance depending on usage conditions. Common graphite and metal-based BPs offer good conductivity, but they have their drawbacks. Graphite lacks strength and is costly to process, while metal-based BPs need additional surface treatments to prevent corrosion. In recent years, composite bipolar plates have gained widespread attention due to their excellent conductivity, mechanical properties, and outstanding corrosion resistance. In this study, we used natural graphite flakes as the main conductive filler and nano-copper as the secondary conductive filler, with epoxy resin as the binder. The composite bipolar plate was prepared using a hot-pressing method. The study found that adding 1 wt% of nmCu can increase the conductivity of the composite BP by 75.2%, but it decreases the flexural strength by 26.84%. The prepared nmCu/G/EP composite BP exhibits an ASR of only 4.00 mΩ cm2 and a corrosion current density of 2.615 × 10−7 A/cm2, meeting the DOE 2025 expectations. After conducting Cu2+ leaching experiments on the prepared composite BP, single-cell performance testing showed a maximum power density of 0.556 W/cm2. This study expands the range of conductive fillers for composite BPs, no longer limited to carbon-based conductive fillers.