Effect of the concentration of the support electrolyte on the performance of Anion Exchange Membrane Water Electrolysis

Effect of the concentration of the suThe ongoing global energy transition is driven by the urgent need to reduce greenhouse gas emissions and achieve long-term sustainability in energy production, further highlighted by geopolitical tensions. Among the various alternatives, hydrogen has emerged as a promising energy carrier due to its high gravimetric energy density and its potential to serve as a bridge between intermittent renewable sources and stable energy demand. Water electrolysis represents the most direct and environmentally friendly pathway to produce hydrogen when powered by renewable electricity. Within this context, anion exchange membrane water electrolysis (AEMWE) has recently gained increasing attention as a hybrid technology that combines the advantages of proton exchange membrane (PEM) and alkaline systems. AEMWE enables the use of non-noble metal catalysts and less corrosive electrolytes while maintaining high ionic conductivity and compact cell design. Nevertheless, challenges remain concerning long-term stability, membrane durability, and the concentration of the supporting electrolyte, which directly affects cell efficiency and kinetics. This thesis focuses on the influence of the support electrolyte concentration on the performance of AEMWE cells. Two electrochemical cells were assembled and tested under controlled operating conditions to isolate the effects of electrolyte concentration and feeding configuration. The experimental campaign included polarization tests, Tafel analysis, and electrochemical impedance spectroscopy (EIS). Furthermore, both dry-cathode and dual-feed modes were investigated to evaluate the role of water management and electroosmotic transport phenomena. The analysis also involved equivalent circuit modeling through a modified Randles circuit with two constant-phase elements (CPEs), allowing for a deeper interpretation of the interfacial processes and resistive components in the system. The results demonstrated that the electrolyte concentration has a decisive impact on both kinetic and resistive behavior of the cell. Higher electrolyte concentrations improved ionic conductivity and reduced polarization losses, leading to more stable and efficient operation. Conversely, lower concentrations increased both the activation and ohmic contributions. The comparative study between feeding modes revealed that the dry-cathode configuration ensures greater long-term stability due to more favorable water transport dynamics.pport electrolyte on the performance of Anion Exchange Membrane Water Electrolysis.