In-Situ Electrolyzer Monitoring Using Electrochemical Impedance Spectroscopy (EIS)
Authors: Dass Sasha , Barber Christopher , Fischl Kate , Garber Leah , Harrington Brian , iPEK Sarven , Marathe Radhika , Montalvo Tony , O'Byrne Nicola , Yellepeddi Atulya , Seidel Sheila , Zheng Sue 
Published: September 2023

The development of technologies that improve the efficiency and reliability of green hydrogen production and distribution systems is key to lowering the cost and spurring widespread adoption of hydrogen. Electrolyzer reliability is affected by factors such as degradation of catalytic materials and development of anomalies in the membrane electrode assembly, which can in turn lead to hazardous mixing of Hydrogen and Oxygen. Most methods to lower the manufacturing cost further negatively affect the reliability. The effect of such degradation can be alleviated with improved cell monitoring technology [i]—for instance, the ability to predict failures in advance enables predictive maintenance to improve system utilization and minimize impact to the amount of hydrogen produced.
Electrochemical Impedance Spectroscopy (EIS) is a widely used tool in lab settings to understand the properties of electrochemical cells. However, due to a combination of cost and technological barriers, scaling EIS technology to in-situ, in-operando monitoring of megawatt scale electrolyzer stacks has proven challenging. In this talk, Analog Devices presents Andromeda (Fig. 1) – a system that can monitor small electrolyzer stacks (up to 4 cells, 100cm2 at current densities up to 3A/cm2) in-situ. In a lab environment, Andromeda enables the use of EIS during long degradation studies with arbitrary power supplies without interrupting the study. We will show that, with appropriate modifications to the hardware, the architecture of the Andromeda system can be scaled to monitor Megawatt-scale electrolyzer stacks.
We will additionally show data gathered on small cells that indicates that EIS can be a good indicator of failure mechanisms in an electrolytic cell [ii, iii], which further indicates that in-situ monitoring using EIS can be a powerful tool to monitor electrolyzer state-of-health. As an example, Figure 2 shows that corresponding I/V curves show no discernible difference between a baseline cell and cells with pinholes, indicating that small pinholes, which can be safety hazards, can be challenging to detect during operation. Examination of EIS data (Figure 3a), on the other hand, reveals a widening and depression of the semicircle in the curve from the cell with the pinhole. Detectability has also been demonstrated for defects such as catalyst degradation, membrane poisoning, and drifts in mass transport properties within the cell, proving that an in-situ monitoring system, when combined with modeling and AI, has the potential to give asset owners visibility into their operations that will improve utilization, decrease cost and enable safer production of hydrogen at scale.
Future work on the integration of semiconductor technology into hydrogen equipment has focused on bypassing failing cells in the stack [iv] (Figure 4) and designing power systems that enable electrolyzers to exploit existing economies of scale.
References:

“EIS MONITORING SYSTEMS FOR ELECTROLYZERS “, Patent pending: US 63/150,308

Siracusano, Stefania et al. “Electrochemical Impedance Spectroscopy as a Diagnostic Tool in Polymer Electrolyte Membrane Electrolysis.” Materials (Basel, Switzerland) vol. 11,8 1368. 7 Aug. 2018

Rakousky, et al. “An analysis of degradation phenomena in polymer electrolyte membrane water electrolysis”, Journal of Power Sources, vol. 326, 2016, Pages 120-121

ELECTRICALLY PARALLEL ELECTROLYZERS AND ELECTROLYZERS WITH BYPASSABLE CELLS FOR THE PRODUCTION OF HYDROGEN, Patent pending: US 17/336,929

Figure 1