Challenges and Strategies of Anion Exchange Membranes in Hydrogen-electricity Energy Conversion Devices.

ABSTRACT

Alkaline hydrogen-electricity energy conversion technologies, involving anion exchange membrane fuel cells (AEMFCs) and anion exchange membrane water electrolyzers (AEMWEs) are more appealing than the acidic counterparts due to the elimination of precious metal catalysts. However, the physicochemical properties of anion exchange membrane (AEMs), i.e., ionic conductivity, mechanical strength, stability, etc., are inferior to that of proton exchange membranes (PEMs), thus hindering these alkaline technologies from practical employment. To promote their development, we summarize the main challenges and the corresponding strategies of AEMs for the application of AEMFCs and AEMWEs in this review. The hydroxide transportation mechanism, ion exchange capacity, hydration and microscopic morphology that are relevant to the ionic conductivity are discussed firstly. Following the ionic conductivity, another obstacle, stability of AEMs is comprehensively described in terms of alkaline stability, mechanical stability and electrochemical stability. Upon integrating into the devices, water management, carbonation effect and membrane-electrode interface that are critical to the cell performance are highlighted as well. This review is anticipated to provide insights into the AEM design for hydrogen-electric energy conversion devices, thus accelerating the widespread commercialization of these promising technologies.