Low-frequency experimental method for measuring the electric double-layer capacitances of multi-cell electrolysis stacks based on equivalent circuit model

In recent years, the green hydrogen production via water electrolysis has acquired significant attention, and the dynamic operation of electrolysis stacks has become a crucial research area. The electric double-layer capacitance (EDLC) is the primary factor indicating the performance of the stack and affecting the dynamic behavior of the electrolysis stack. High-frequency testing methods are commonly used to measure the EDLCs of electrolysis cells in laboratory, but these methods are not suitable for cost-efficiency and a bottleneck of the engineering power electronic devices. This study proposes a novel square-wave pulse current (SPC) method for determining the EDLCs of multi-cell electrolysis stacks using industrial rectifiers. The response of the stack subjected to SPC is analyzed based on a semi-empirical equivalent circuit (SEEC) model. The feasibility of the proposed method is verified through experiments on a 2 Nm3/h alkaline water electrolysis stack, and an accuracy of 2.67% is obtained.

Automated summary

In recent years, there has been significant attention on the production of green hydrogen through water electrolysis, with a focus on the dynamic operation of electrolysis stacks. The electric double-layer capacitance (EDLC) is a key factor in determining stack performance and influencing dynamic behavior. High-frequency testing methods commonly used in laboratories are not suitable for cost-efficiency and pose a bottleneck for engineering power electronic devices. This study proposes a novel square-wave pulse current (SPC) method to determine EDLCs of multi-cell electrolysis stacks using industrial rectifiers. Experimental verification on a 2 Nm3/h alkaline water electrolysis stack achieved an accuracy of 2.67%.