Real-time diagnosis of Nafion membrane degradation in PEM electrolyzers via conductivity-based kinetic modeling

Membrane degradation remains one of the main factors limiting the efficiency and lifespan of proton-exchange membrane electrolysers for green hydrogen production. This work investigates the conductivity of effluent water as a non-invasive variable for monitoring chemical membrane degradation during early stages of continuous electrolyzer operation. Experimental results show a clear correlation between conductivity and fluoride ion concentration, widely recognized as an indicator of Nafion chemical degradation. Based on these observations, a mechanistic kinetic model is proposed to describe the temporal evolution of conductivity as a function of applied current density and operating time, considering that degradation is induced by hydroxyl radicals and the formation of hydrofluoric acid. The model reproduces experimental trends with good agreement and provides a physicochemically well-founded framework for interpreting conductivity variations under different galvanostatic operating conditions. The results show that real-time, in-situ monitoring of membrane degradation is possible using a simple and widely available detection technology, without interrupting normal electrolyzer operation. These results highlight the potential of conductivity-based diagnostics as a practical tool for assessing membrane health in PEM electrolyzers and provide a basis for developing scalable monitoring strategies for industrial applications. • Real-time method tracks membrane degradation without damaging the system. • Water conductivity linked to fluoride release as a degradation indicator. • Kinetic model predicts degradation based on applied current density and time. • Method validated under varied conditions with strong data correlation. • Future work includes sensor upgrades and industrial-scale validation.