Material Development Strategy Guided by Degradation Analysis Under Dynamic Load in Proton Exchange Membrane Water Electrolysis

To realize the hydrogen economy and achieve net-zero carbon emission, practical implementation of water electrolysis (WE) technique is of prime importance. Among the WE techniques, proton exchange membrane water electrolysis (PEMWE) has attracted much attention due to its high performance, compact design, and fast response. However, the lack of an appropriate evaluation protocol for durability, and the lack of understanding on degradation behavior of each component in PEMWE hinder its widespread application. In this presentation, degradation behavior under dynamic load-based accelerated stress test (AST) protocols will be discussed to guide material development strategy. Load ranges were varied by changing the low voltage limit (LVL) between 1.4 V and 1.9 V while fixing the high voltage limit at 2.2 V. The used AST protocols can simply mimic solar profiles characterized by high ramp rates and loads fluctuations. The AST protocols with LVL 1.4 V and LVL 1.5 V resulted in contrast degradation behaviors, showing an increase and decrease in performance after the test, respectively. The performance decrease, observed for the LVL 1.4, was ascribed to the fuel cell-like operation mode with reversal current occurrence, considered as additional stress factor for the cathode catalyst degradation. For the LVL 1.5, the slight performance increase is ascribed to the membrane thinning and/or catalyst dissolution at the anode/catalyst interface, which temporarily increases roughness, thereby exposing more active sites to the electrolyte. The AST protocols with LVL 1.7 and LVL 1.9 resulted in the substantial increases in mass transport overpotential. Given the cross-sectional SEM analyses, the results is presumably attributed to the bubble nucleation and subsequent degradation on membrane/catalyst and/or diffuse layer/catalyst interfaces together with decrease in catalyst layer porosity. Meanwhile, a comparative AST protocol with steady-state load (2.2 V) resulted in the performance decay, mostly attributed to the increase in ohmic overpotential due to the Ti porous layer passivation. The degradation study can suggest a practical guidance for understanding degradation behavior of each component, and for material development strategies in designing durable PEMWE system.