Operating limits and Durability of Water electrolyzers

Flexible operation of water electrolyzers must protect gas purity and safety while limiting wear. This review brings these needs together by defining the operating windows that govern alkaline, polymer-electrolyte, and anion-exchange devices: minimum safe load, ramp and hold limits, compression effects, and H₂-in-O₂ and O₂-in-H₂ thresholds. We explain the failure mechanisms these limits are meant to avoid, including catalyst dissolution or support corrosion, ionomer degradation, interfacial loss, and membrane or separator crossover. We show how low-load and transient operation shift stresses and how gas-train lags from dryers, filters, and compressors can create short off-spec periods that matter for safety and lifetime. Building on this, we consolidate materials and design responses such as stabilized supports, tuned catalyst-ionomer interfaces, crossover-resistant separators, and water-quality control. We also outline diagnostics that make results comparable: purity traces during ramps, crossover versus current curves, and an EIS cadence with standardized lifetime metrics. Finally, we connect device behavior to techno-economic implications, mapping constraints to model inputs including capacity-factor derates, transition losses, purity penalties, and durability-driven replacement scheduling, yielding practical guidance for durable real-world operation. The focus is practical, concise, and immediately actionable.