High performance polymer-based anion exchange membranes for alkaline fuel cells
Fuel cell technology shows a great potential of replacing traditional fossil energies due to its high efficiency and close to zero emission. Alkaline fuel cells also known as anion exchange membrane (AEM) fuel cell attracts growing interest due to its advantages over the most intensively developed and widely commercialized PEMFCs on cathode kinetics and ohmic polarization, low cost, stability, and durability of material. AEM is the key component in such sustainable devices to be investigated in order to satisfy the needs of the technology.
The current project goal is the development of alkaline fuel cell (AFC) and polymer-based anion exchange membranes for it. Also, the project aims to improve the ion conductivity and mechanically stability by investigation of various polymer networks, polymer blends and functionalization of those.
1) Innovative and highly conductive anion-exchange membranes for all solid state alkaline fuel cells will be developed and investigated. The OH--conductivity in the range of 10-1-10-2 S/sm and controllable swelling degree will be achieved;
2) The research results on material synthesis and characterization, performance will be published in leading international peer-reviewed journals of editorial offices such as Elsevier, International Electrochemical Society:
- at least 2 (two) articles and (or) reviews in peer-reviewed scientific publications on the scientific direction of the project, indexed in the Science Citation Index Expanded Web of Science and (or) having a CiteScore percentile in the Scopus database of at least 50 (fifty);
- at least 1 (one) article or review in a peer-reviewed foreign or domestic publication recommended by CCESME MOS RK;
Also the results will be presented at international conferences.
3) 1 (one) patent application for an invention will be prepared and submitted to Kazakhstan parent office.
4) Establishment of international collaboration with the partners will bring novel expertise to Kazakhstan both in science and education of young specialists.
Results for 2021
As a result of the research, PVA was chosen as the main component of the AEM due to the possibility of using aqueous solutions. To increase the membrane conductivity, we used the method of polymer quaternization with quaternary ammonium groups. The successful quaternization process was proven by FTIR spectroscopy, which showed the presence of C-N bonds in the polymer structure.
To improve the mechanical and chemical stability of the OH- conducting membrane, polyethyleneimine was added to the composite membrane, which forms hydrogen bonds with PVA due to the presence of ammonium bonds in the structure. And hydrogen bonds, in turn, improve the mechanical stability of the membrane. Also, to improve the conductivity of the membrane, polyethyleneimine was quaternized, which was confirmed by IR spectroscopy.
Initially, density functional calculations were performed to study the complexation of a hydroxide ion with eight different head groups of ammonium cations in an anionic membrane. The obtained values of the LUMO energies for six different head groups of ammonium cations using the density functional theory showed the following order of chemical stability: f) pyridinium< e) 1,4-diazabicyclo [2.2.2] octane< d) trimethylammonium< c) n-methylpiperidine< b) guanidium< a) trimethylammonium with hexyl spacer. In addition, the above tendency for alkaline stability, calculated by the density functional theory method, is also consistent with experimental results from the literature
The electrospinning method was used to obtain AEM by integrating an OH- conducting polymer, which is quaternized PVA, with a stable composite polymer network - quaternized PEI. The resulting nanofibers showed fairly high mechanical and chemical stability. However, to improve these indicators, different types of crosslinking agents were used: glutaraldehyde, TEOS, MEMO and titanium isopropoxide.
In order to obtain homogeneous nanofibers, the electrospinning solution has one of the most important roles. In this regard, laboratory work was carried out to improve and optimize the composition of the solution, different solvents were selected, the ratios of the components, and also the parameters of the solution preparation (temperature, time, etc.) were changed. Based on the results of the work, the most optimal ratios and components were derived to obtain homogeneous nanofibers.
Research group members: