Anion Exchange Membranes for Fuel Cell Application: A Review

Abstract

The fuel cell industry is the most promising industry in terms of the advancement of clean and safe technologies for sustainable energy generation. The polymer electrolyte membrane fuel cell is divided into two parts: anion exchange membrane fuel cells (AEMFCs) and proton exchange membrane fuel cells (PEMFCs). In the case of PEMFCs, high-power density was secured and research and development for commercialization have made significant progress. However, there are technical limitations and high-cost issues for the use of precious metal catalysts including Pt, the durability of catalysts, bipolar plates, and membranes, and the use of hydrogen to ensure system stability. On the contrary, AEMFCs have been used as low-platinum or non-platinum catalysts and have a low activation energy of oxygen reduction reaction, so many studies have been conducted to find alternatives to overcome the problems of PEMFCs in the last decade. At the core of ensuring the power density of AEMFCs is the anion exchange membrane (AEM) which is less durable and less conductive than the cation exchange membrane. AEMFCs are a promising technology that can solve the high-cost problem of PEMFCs that have reached technological saturation and overcome technical limitations. This review focuses on the various aspects of AEMs for AEMF application.

Anion-exchange membranes with internal microchannels for water control in CO2 electrolysis

“…42 Additionally, future work should seek to use in situ techniques of water management, such as neutron imaging, 43 X-ray tomography, 44 and magnetic resonance imaging 45 that have been used to measure water content in fuel cells to better relate changes in conductivity to changes in water content. 46 It is important to note that all the observed resistance values are higher than expected, with typical values for membranes of this thickness being between 4 to 10 U cm 2 , 47,48 and that the resistance is highly sensitive to the electrolyte concentration in the internal channels. Although electrolyte concentration is known to affect polymer conductivity, 49 the internal channels are small relative to the distance between them, and hence the external electrolyte should not dominate the membrane's conductivity.…”

Alcohol Diffusion in Alkali-Metal-Doped Polymeric Membranes for Using in Alkaline Direct Alcohol Fuel Cells

“…However, in comparison to acid proton exchange membrane fuel cells (PEMFCs), the alkaline medium rendered by anion exchange membrane fuel cells (AEMFCs) presents advantages such as the potential to use non-precious-metal catalysts. Moreover, alkaline membrane water electrolysis is a relatively new technology with the advantages of both alkaline water electrolysis (AWE) and proton exchange membrane water electrolysis (PEMWE), overcoming some of their limitations [ 7 ]. This technology has been scarcely investigated so far [ 8 ].…”

Design and simulation for improved performance via pump‐less direct ethanol fuel cell for mobile application

“…The discrepancy in performance was due to the higher number of by‐products produced during the electrochemical oxidation reaction of both methanol and glycerol compared to ethanol, which only produced acetate and hence reduced the potential of catalyst poisoning. The high performance of AEM DEFCs is due to the faster reaction kinetics in alkaline medium compared to under acidic medium and low overpotential in the electrochemical reaction in high pH condition 45 . Despite the incredibly enhanced AEMs performance, the principal properties of AEMs are not comparable to PEMs because of the low ionic (OH − ) conductivity 46 and degradation of cationic group as well as polymer backbones 47 .…”

“…The high performance of AEM DEFCs is due to the faster reaction kinetics in alkaline medium compared to under acidic medium and low overpotential in the electrochemical reaction in high pH condition. 45 Despite the incredibly enhanced AEMs performance, the principal properties of AEMs are not comparable to PEMs because of the low ionic (OH À ) conductivity 46 and degradation of cationic group as well as polymer backbones. 47 Ionic conductivity can be increase by increasing ionic exchange capacity (IEC), but it will increase water uptake and cause membrane swelling.…”