Investigating Electrode Resistance Separation and Cost-Effective Electrode Approaches in Proton Exchange Membrane Water Electrolysis

Abstract

The fourth industrial revolution has increased fossil fuel consumption and greenhouse gas emissions, necessitating urgent solutions for climate change. Hydrogen energy, particularly green hydrogen produced via water electrolysis, is vital for carbon neutrality. Proton exchange membrane water electrolysis (PEMWE) is crucial for producing green hydrogen, a clean energy carrier that reduces greenhouse gas emissions. Despite its benefits, the high cost of noble metal catalysts and perfluorosulfonic acid (PFSA) polymers requires research into cost-effective alternatives to enhance the economic viability of PEMWE systems. This thesis presents a study on membrane electrode assembly (MEA) performance and resistance analysis and explores hydroxypropyl methylcellulose (HPMC) as a binder alternative to Nafion® ionomer in PEMWE systems. Chapter 2 contains the analysis of the resistance of MEAs with different IrO2 loadings on the porous transport layer (PTL). Using distribution of relaxation times (DRT) analysis, the study identifies proton, charge, and mass transport resistances, demonstrating that DRT analysis provides clearer separation of resistances than electrochemical impedance spectroscopy (EIS). Chapter 3 describes for investigation of crosslinking of hydroxypropyl methylcellulose (HPMC) as a cost-effective alternative to Nafion®. Crosslinking HPMC with citric acid improved its durability and hydrophilicity. Performance evaluations indicated that crosslinked HPMC electrodes performed better than both Nafion® and HPMC electrodes, with lower voltage and resistance. The crosslinked HPMC electrode heat-treated at 140 ℃ showed the best performance and durability. These findings suggest that crosslinked HPMC enhances hydrophilicity and facilitates better water and proton transport, improving PEMWE system performance. In conclusion, this thesis demonstrates the effectiveness of DRT analysis in PEMWE systems and identifies crosslinked HPMC as a viable, cost-effective alternative to Nafion®, contributing to the development of efficient and sustainable PEMWE technologies.