Identifying and Quantifying Loss Sources in Anion-Exchange Membrane Water Electrolyzers

Area of Science:

• Electrochemistry
• Materials Science

Background:

• Anion-exchange membrane water electrolyzers (AEMWEs) offer a sustainable alternative using precious-metal-free catalysts and fluorine-free membranes.
• Understanding performance limitations is crucial for commercializing AEMWE technology.

Purpose of the Study:

• To identify and quantify performance loss sources in AEMWEs under various operating conditions.
• To develop an analytical model for analyzing electrochemical processes using Distribution Function of Relaxation Times (DFRT).

Main Methods:

• Utilized electrochemical impedance spectroscopy (EIS) combined with MATLAB-based genetic programming.
• Developed an analytical DFRT model to differentiate Faradaic and non-Faradaic processes.
• Investigated effects of KOH concentration, dry cathode operation with different anode electrolytes, temperature, and membrane type.

Main Results:

• Decreased KOH concentration in the anode significantly increases ionic transport resistance, reducing performance.
• Dry cathode operation with KOH anode provides performance comparable to dual-electrolyte systems due to effective water back-diffusion.
• Using pure water as anode electrolyte with a dry cathode drastically increases resistance and hinders ionic transport.

Conclusions:

• DFRT analysis effectively separates and quantifies electrochemical phenomena in AEMWEs, simplifying system design.
• Optimizing anode electrolyte and ionomeric materials is critical for improving AEMWE efficiency and enabling commercialization.
• This approach advances the development of efficient AEMWEs for clean hydrogen production.