Systematic Degradation Analysis in Renewable Energy-Powered Proton Exchange Membrane Water Electrolysis

Abstract

Given the focus on a green hydrogen economy for a sustainable future, it is crucial to understand the degradation features of proton exchange membrane water electrolysis (PEMWE). However, despite numerous studies that aim to uncover these features under various loads such as pulse shape cycling and steady-state, which are commonly employed to simulate the intermittent characteristics of renewable energy source (RES) power, there is a notable lack of reported experiments that accurately replicate the complex loads observed in realistic RES scenarios. In this study, a high-resolution, realistic solar profile was first simulated to examine the degradation features compared to a set of typical stability tests, including steady-state and dynamic cycling loads. Our simulation method is distinct in that it directly utilizes the P-V and I-V characteristics of the solar array at different irradiation levels. Notably, our simulated solar profile had an exceptionally high resolution of 1 second, and the shortest step duration among the studied profiles, which allowed maximizing the effect of high-ramp rate events in RES power. Additionally, the resulting degradation features were systematically scrutinized through comprehensive analysis, including electrochemical, spectroscopic, and microscopic characterization, along with a close structure examination of the catalyst/membrane interface, membrane degradation, and Ti porous transport layer passivation. A high-resolution realistic solar profile is featured by the activation overpotential recovery during rest "night time" periods, elevated fluoride release rate due to cycling to low loads (49.17 & mu;g cm-2), insignificant Ti passivation (0.41 nm) and Pt dissolution/diffusion to the anode (0.69 at% of Ir and 0.17 at% of Pt were found in the membrane adjacent to the anode catalyst layer). These findings can provide valuable guidelines for establishing a suitable RES-mimicking accelerated stress test protocol to diagnose system durability, and for designing durable materials for long-term operation. More importantly, the insight gained can bridge the gap between laboratory-scale investigations and on-site RES-coupled PEMWE operations, addressing current limitations in fundamental understanding of degradation mechanisms. A high-resolution, realistic solar profile was first simulated and employed to operate the proton exchange membrane water electrolysis. The resulting degradation features were extensively scrutinized and compared to a set of typical stability tests.