Preparation and Study of Sulfonated Co-Polynaphthoyleneimide Proton-Exchange Membrane for a H2/Air Fuel Cell

Development of High-Performance Hydrogen-Air Fuel Cell with Flourine-Free Sulfonated Co-Polynaphthoyleneimide Membrane

This paper presents research on the technological development of hydrogen-air fuel cells with high output power characteristics using fluorine-free co-polynaphtoyleneimide (co-PNIS) membranes. It is found that the optimal operating temperature of a fuel cell based on a co-PNIS membrane with the hydrophilic/hydrophobic blocks = 70/30 composition is in the range of 60-65 °C. The maximum output power of a membrane-electrode assembly (MEA), created according to the developed technology, is 535 mW/cm², and the working power (at the cell voltage of 0.6 V) is 415 mW/cm². A comparison with similar characteristics of MEAs based on a commercial Nafion 212 membrane shows that the values of operating performance are almost the same, and the maximum MEA output power of a fluorine-free membrane is only ~20% lower. It was concluded that the developed technology allows one to create competitive fuel cells based on a fluorine-free, cost-effective co-polynaphthoyleneimide membrane.

Hydrocarbon-Based Composite Membrane Using LCP-Nonwoven Fabrics for Durable Proton Exchange Membrane Water Electrolysis

A new hydrocarbon-based (HC) composite membrane was developed using liquid crystal polymer (LCP)-nonwoven fabrics for application in proton exchange membrane water electrolysis (PEMWE). A copolymer of sulfonated poly(arylene ether sulfone) with a sulfonation degree of 50 mol% (SPAES50) was utilized as an ionomer for the HC membranes and impregnated into the LCP-nonwoven fabrics without any surface treatment of the LCP. The physical interlocking structure between the SPAES50 and LCP-nonwoven fabrics was investigated, validating the outstanding mechanical properties and dimensional stability of the composite membrane in comparison to the pristine membrane. In addition, the through-plane proton conductivity of the composite membrane at 80 °C was only 15% lower than that of the pristine membrane because of the defect-free impregnation state, minimizing the decrease in the proton conductivity caused by the non-proton conductive LCP. During the electrochemical evaluation, the superior cell performance of the composite membrane was evident, with a current density of 5.41 A/cm² at 1.9 V, compared to 4.65 A/cm² for the pristine membrane, which can be attributed to the smaller membrane resistance of the composite membrane. From the results of the degradation rates, the prepared composite membrane also showed enhanced cell efficiency and durability during the PEMWE operations.

Ionic Mobility in Ion-Exchange Membranes

Membrane technologies are widely demanded in a number of modern industries. Ion-exchange membranes are one of the most widespread and demanded types of membranes. Their main task is the selective transfer of certain ions and prevention of transfer of other ions or molecules, and the most important characteristics are ionic conductivity and selectivity of transfer processes. Both parameters are determined by ionic and molecular mobility in membranes. To study this mobility, the main techniques used are nuclear magnetic resonance and impedance spectroscopy. In this comprehensive review, mechanisms of transfer processes in various ion-exchange membranes, including homogeneous, heterogeneous, and hybrid ones, are discussed. Correlations of structures of ion-exchange membranes and their hydration with ion transport mechanisms are also reviewed. The features of proton transfer, which plays a decisive role in the membrane used in fuel cells and electrolyzers, are highlighted. These devices largely determine development of hydrogen energy in the modern world. The features of ion transfer in heterogeneous and hybrid membranes with inorganic nanoparticles are also discussed.