Emerging Polybenzimidazole Membranes for Green Energy Conversion Devices

Dear colleagues:

Тhe introduction of the third decade of the emerging green energy revolution and ,hydrogen based energetics in particular, has given rise of the use of electrochemical devices for energy conversion such as hydrogen fuel cells, co-generation systems, water and low-alcohol electrolyzers, and flow batteries, among others. In all these devices, a core component is the solid polymer electrolyte separation membrane, where the thermally and chemically robust aromatic polybenzimidazoles (PBI’s) and their ionomeric derivatives are a significant material of choice since the pioneering discovery of the peculiar and promising proton conductivity properties of amphoteric PBI membranes doped with ortho-phosphoric acid (PBI/PA) by R. F. Savinell et al. in the mid-1990s. Since then, PBI based membranes doped with either mineral acids (H⁺ conductive), alkali bases (OH^- conductive), ionic liquids, or ion-exchange derivatives with their intrinsic ionic conductivity have not only gained great popularity among the research community but most significantly have found their way to real commercialization as a close rival of perfluorinated super acid ionomeric membrane-based technology. During this time, two main groups of PBI membrane emerged: (i) the so-called ion-solvating PBI membranes, where the PBI matrix is solvated by an excess number of low-electrolyte molecules with predominantly ionic interactions within the free electrolyte media, and (ii) the ion-exchange derivative PBI membranes with significantly expressed hydrated form self-conductivity, where the main chain PBI is chemically modified with ion-exchange side groups. In both cases, factors such as reaching highly concentrated forms of electrolyte doping for the ion-solvating and high ionomeric density and particularly high alkaline concentration stability for the ionomeric based PBI membrane are still challenging. Here, the ion-enhancing and mechanical reinforcing properties of different inorganic fillers (e.g., natural and synthetic (alumo)silicates, carbon based micro- and nanofillers like graphene and carbon nanotubes, etc.) play significant intermediate role in PBI membranes’ property tuning.

This Special Issue on Emerging Polybenzimidazole Membranes for Green Energy Conversion Devices in the journal Membranes seeks contributions to assess state-of-the-art and conceptual developments in the field of PBI separation membranes for fuel cells, electrolyzers, and flow batteries. Topics include, but are not limited to, new PBI membrane developments, composite membranes, chemical modification and cross-linking, manufacturing/stabilization techniques, characterization, fuel cell/electrolyzers and ox-red flow-battery application, industrial exploitation, and perspective. Authors are invited to submit their latest results—both original papers and reviews are welcome.

Dr. Hristo Penchev
Prof. Dr. Evelina Slavcheva
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Membranes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• PBI membrane developments
• composite membranes
• chemical modification and cross-linking
• manufacturing/stabilization techniques
• fuel cell/electrolyzers and ox-red flow-battery application
• industrial exploitation and perspective