Separators and Membranes for Advanced Alkaline Water Electrolysis.

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Traditional alkaline water electrolysis (AWE) relies on diaphragms and high concentration (5-7 M) KOH solutions.
• The phase-out of asbestos diaphragms has driven the adoption of polymeric diaphragms as the current standard.
• Emerging technologies like ion solvating membranes and anion exchange membranes (AEM) offer alternatives with potential for lower KOH concentrations.

Purpose of the Study:

• To review advancements in membrane technologies for alkaline water electrolysis.
• To compare the performance and characteristics of polymeric diaphragms, ion solvating membranes, and AEM.
• To highlight the potential of newer membranes in achieving efficient hydrogen production with reduced KOH concentrations.

Main Methods:

• Review of recent developments in polymeric diaphragms for AWE.
• Analysis of ion solvating membranes and their conductivity in lower KOH concentrations (1 M).
• Examination of anion exchange membrane (AEM) water electrolysis (WE) systems, focusing on KOH concentration trade-offs and AEM longevity.

Main Results:

• Polymeric diaphragms are the current state-of-the-art in AWE.
• Ion solvating membranes show promise for high conductivity in 1 M KOH.
• AEM WE technology has seen significant improvements in membrane lifetime and can benefit from KOH solutions to mitigate electrode issues.

Conclusions:

• The field of alkaline water electrolysis is advancing with new membrane technologies.
• Ion solvating membranes and AEM represent promising alternatives to traditional diaphragms, enabling operation at lower KOH concentrations.
• Future AWE and AEM WE systems may converge due to improved membrane performance and electrode stability.