Dynamic electrical degradation of PEM electrolyzers under renewable energy Intermittency: Mechanisms, diagnostics, and mitigation strategies – A comprehensive review

Proton Exchange Membrane (PEM) electrolyzers are pivotal for green hydrogen production, yet their widespread deployment is hindered by durability issues under real-world dynamic conditions, particularly when powered by intermittent renewable sources. This review explores the main degradation mechanisms affecting PEM electrolyzers, focusing on electrical, thermal, and cycling-induced aging phenomena. Operating at high current densities (up to 3 A cm −2 ) accelerates internal electrical degradation, with ohmic resistance rising by ∼50 μV/h due to titanium oxide formation in porous transport layers. Elevated temperatures (>100 °C) intensify membrane thinning, hotspot development, and hydrogen bubble accumulation reducing device lifetime from 35,000 to 8700 h (e.g., between 333 K and 353 K). Frequent ON/OFF cycling further degrades performance through catalyst dissolution and electrode delamination, causing voltage drifts of 20–50 μV/h. The originality of this work lies in its multiphysics and integrative perspective, systematically linking these degradation pathways with corresponding mitigation strategies, all supported by experimental data. Key solutions include dynamic electrical control (up to 80 % effective), advanced thermal regulation (up to 70 % effective), and real-time diagnostics via Electrochemical Impedance Spectroscopy (EIS). By combining physical modeling with experimental insights, this review offers a comprehensive framework for understanding and reducing degradation in PEM electrolyzers. It provides valuable guidance for improving their durability and reliability under variable operating regimes. Ultimately, this work aims to support the accelerated industrial adoption of PEM technology in renewable energy systems subject to dynamic and fluctuating conditions. • PEM electrolyzers face major durability losses during dynamic operation from renewable energy intermittency. • Key degradation modes: rising ohmic resistance (≤50 μV/h), catalyst loss, and membrane thinning >100 °C. • ON/OFF cycling accelerates aging, causing voltage drift and reduced service life. • This review integrates thermal, electrical, and mechanical degradation under real-world conditions. • Mitigation: dynamic control (80%), thermal management (70%), and EIS diagnostics to boost long-term performance.