Exploring the Effectiveness of Polypyrrole Coating Doped with TiN and CrN Nanoparticles on Aluminum Alloy-Based Bipolar Plates for PEMFC Application

Proton exchange membrane fuel cells (PEMFCs) are high-efficiency, low-emission energy conversion devices, making them suitable for applications such as transportation and stationary power generation. A critical component of PEMFCs is the bipolar plate (BP), which plays a key role in conducting electricity, distributing gases, and managing water within the cell. Ensuring the performance and durability of BPs is essential, and 5052 aluminum alloy (AA) is frequently utilized due to its lightweight and conductive properties. However, the susceptibility of AA to corrosion requires effective protective coatings to enhance its longevity and functionality. This study explores the effectiveness of polypyrrole (PPy) coatings doped with titanium nitride (TiN) and chromium nitride (CrN) nanoparticles on 5052 AA substrates. The PPy and PPy-TiN/CrN coatings significantly improve the corrosion resistance, polarization resistance, and protection efficiency of the 5052 AA. Among the various coatings tested, the PPy-TiN0.15/CrN0.15 coating demonstrates the best performance, with a positive corrosion potential (Ecorr) of 0.027 V and a notably lower corrosion current (Icorr) of 0.55 μA/cm2. This coating also exhibits the highest polarization resistance value of 50285.82 Ω/cm2 and achieves a protection efficiency of 54.92%, significantly surpassing that of other coated specimens. Additionally, the PPy-TiN0.15/CrN0.15 coating displays outstanding protective capabilities, with the highest impedance value (Z) of 3510.53 Ω/cm2, highlighting its superior ability to prevent corrosive ion penetration as confirmed by electrochemical impedance spectroscopy. To further analyze the surface morphology and characteristics of this coating, additional characterization studies will be conducted, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and contact angle measurements. These comprehensive analyses will provide deeper insights into the structural and functional properties of the PPy-TiN0.15/CrN0.15 coating, reinforcing its potential application in enhancing the durability and performance of BPs for PEMFC. Interfacial contact resistance (ICR) measurements were performed to assess the electrical performance of the coatings. The PPy-TiN0.15/CrN0.15 coating exhibited the lowest ICR value of 26.8 mΩ/cm2 at a compaction pressure of 1.4 MPa, confirming its improved conductivity and suitability for PEMFC applications.