Synthesis and characterization of benzimidazolium-functionalized polysulfones as anion-exchange membranes

Recent Advances and Challenges in Anion Exchange Membranes Development/Application for Water Electrolysis: A Review

In recent years, anion exchange membranes (AEMs) have aroused widespread interest in hydrogen production via water electrolysis using renewable energy sources. The two current commercial low-temperature water electrolysis technologies used are alkaline water electrolysis (AWE) and proton exchange membrane (PEM) water electrolysis. The AWE technology exhibited the advantages of high stability and increased cost-effectiveness with low hydrogen production efficiency. In contrast, PEM water electrolysis exhibited high hydrogen efficiency with low stability and cost-effectiveness, respectively. Unfortunately, the major challenges that AEMs, as well as the corresponding ion transportation membranes, including alkaline hydrogen separator and proton exchange membranes, still face are hydrogen production efficiency, long-term stability, and cost-effectiveness under working conditions, which exhibited critical issues that need to be addressed as a top priority. This review comprehensively presented research progress on AEMs in recent years, providing a thorough understanding of academic studies and industrial applications. It focused on analyzing the chemical structure of polymers and the performance of AEMs and established the relationship between the structure and efficiency of the membranes. This review aimed to identify approaches for improving AEM ion conductivity and alkaline stability. Additionally, future research directions for the commercialization of anion exchange membranes were discussed based on the analysis and assessment of the current applications of AEMs in patents.

Recent Advancements in Polysulfone Based Membranes for Fuel Cell (PEMFCs, DMFCs and AMFCs) Applications: A Critical Review

In recent years, ion electrolyte membranes (IEMs) preparation and properties have attracted fabulous attention in fuel cell usages owing to its high ionic conductivity and chemical resistance. Currently, perfluorinatedsulfonicacid (PFSA) membrane has been widely employed in the membrane industry in polymer electrolyte membrane fuel cells (PEMFCs); however, NafionTM suffers reduced proton conductivity at a higher temperature, requiring noble metal catalyst (Pt, Ru, and Pt-Ru), and catalyst poisoning by CO. Non-fluorinated polymers are a promising substitute. Polysulfone (PSU) is an aromatic polymer with excellent characteristics that have attracted membrane scientists in recent years. The present review provides an up-to-date development of PSU based electrolyte membranes and its composites for PEMFCs, alkaline membrane fuel cells (AMFCs), and direct methanol fuel cells (DMFCs) application. Various fillers encapsulated in the PEM/AEM moiety are appraised according to their preliminary characteristics and their plausible outcome on PEMFC/DMFC/AMFC. The key issues associated with enhancing the ionic conductivity and chemical stability have been elucidated as well. Furthermore, this review addresses the current tasks, and forthcoming directions are briefly summarized of PEM/AEMs for PEMFCs, DMFCs, AMFCs.

Synthesis and Characterization of Novel Anion Exchange Membranes Based on Semi-Interpenetrating Networks of Functionalized Polysulfone: Effect of Ionic Crosslinking

In this work, anion exchange membranes based on polymer semi-interpenetrating networks were synthesized and characterized for the first time. The networks are composed of sulfonated polysulfone and 1-methylimidazolium-functionalized polysulfone crosslinked covalently with N,N,N′,N′-tetramethylethylenediamine (degree of crosslinking of 5%). In these membranes, sulfonic groups interact electrostatically with cationic groups to form an ionic crosslinking structure with improved alkaline stability. The effect of the ionic crosslinking on the thermal, chemical, mechanical, and electrochemical behavior of membranes was studied. These crosslinked membranes containing sulfonated polysulfone showed higher thermal stability, with a delay of around 20 °C in the onset decomposition temperature value of the functional groups than the crosslinked membranes containing free polysulfone. The tensile strength values were maintained above 44 MPa in all membranes with a degree of chloromethylation (DC) below 100%. The maximum ionic conductivity value is reached with the membrane with the highest degree of chloromethylation. The chemical stability in alkaline medium of the conducting membranes also improved. Thus, the ionic conductivity variation of the membranes after 96 h in a 1 M potassium hydroxide (KOH) solution is less pronounced when polysulfone is replaced by sulfonated polysulfone. So, the ionic crosslinking which joins both components of the blends together, improves the material’s properties making progress in the development of new solid electrolyte for polymeric fuel cells.

Spirocyclic quaternary ammonium cations for alkaline anion exchange membrane applications: an experimental and theoretical study

Spirocyclic quaternary ammonium cation based alkaline anion exchange membranes were synthesized and studied by both experimental and theoretical analysis.