Redox flow batteries (RFBs) are large-scale energy storage systems that enable the use of intermittent renewable energy resources, such as solar and wind power, which may not always be available when energy is being consumed. Unlike other battery technologies, RFBs can store significant amounts of energy in fluids in large reservoirs. The fluids are then flowed through cells to insert (i.e. charging) or to extract energy (i.e. discharging) from the system. Significant improvements in energy storage capacity, power output and material costs are necessary to enable wide-scale deployment of this technology. This fundamental research project will help solve these needs by addressing key barriers in the ion separation membrane component whose performance impacts overall energy efficiency and system lifetime for power generation and energy storage. The existing ion separators are polymer-based, which have inherent shortcomings of inadequate selectivity and material instability that reduce the RFB efficiency and operation life. Similarly, membranes based on inorganic oxides such as ceramics have issues with durability and efficiency. This project aims to demonstrate a new zeolite nanomaterial-based membrane that can approach ideal performance as an ion separator and help unlock the potential of aqueous RFBs for cost-effective energy storage. The findings of this basic research project will advance knowledge on nanomaterial synthesis and ion transport behavior in the new membranes. The multidisciplinary research activities of this program will offer excellent opportunities for training next generation scientists and engineers in the frontiers of emerging energy technologies and critical material development.
This project will focus on a new 2-dimensional zeolite nanosheet tiled ion separation membrane (ZNTM). This project will yield fundamental knowledge on 2D nanomaterial synthesis and ion transport behavior in the new structure of subnanometer-pore 2D nanosheet membranes. Defect-free zeolite membranes, e.g. single crystals, are theoretically capable of conducting protons with high selectivity and exceptional material stability in RFB operations. However, these favorable properties cannot be effectively realized by the conventional mixed matrix zeolite membrane structures because of excessive metal ion crossover through shortcutting intercrystalline spaces and high resistance from a relatively large thickness of membrane. The project will address the chief challenges in synthesizing and property tailoring of 2D ionic sieve crystals and effectively utilize their unique properties by the novel ZNTM structure. Fundamental studies are directed to identify the conditions for synthesizing nanometer-thick zeolite nanosheets with controlled surface chemistry, geometric and dimensional properties (i.e. adequately large width-to-thickness aspect ratios), and channel orientation in preferable direction. Systematic experiments will be carried out to establish an effective methodology for fabricating the ultrathin 2D ZNTM ion separators. The ion selectivity, conductivity, and material stability of the ion separators will be extensively examined to understand their dependences on the microstructure and surface chemistry of the zeolite nanosheets and ZNTM. The ZNTM with verified ion selectivity and minimized electric resistance will be evaluated for full cell RFB operation including performance in battery energy efficiency, power density, thermal stability, and lifetime. The evaluations of the new membranes will be concentrated on the industrially important all-vanadium and ion-chromium RFB chemistries.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
