2-Dimensional Zeolite Nanosheet Tiled Ion Separators for Approaching Ideal Performance in Redox Flow Batteries

氧化还原液流电池（rfb）是一种大型储能系统，可以使用间歇性的可再生能源，如太阳能和风能，这些能源在消耗时可能并不总是可用的。与其他电池技术不同，rfb可以在大型储层的流体中储存大量能量。然后，流体流经电池，从系统中插入（即充电）或提取能量（即放电）。为了实现该技术的大规模部署，储能容量、功率输出和材料成本的重大改进是必要的。这个基础研究项目将通过解决离子分离膜组件中的关键障碍来帮助解决这些需求，这些障碍的性能影响发电和储能的整体能源效率和系统寿命。现有的离子分离器以聚合物为基础，存在选择性不足和材料不稳定等缺点，降低了RFB效率和使用寿命。同样，基于无机氧化物（如陶瓷）的膜也存在耐用性和效率方面的问题。该项目旨在展示一种新的基于沸石纳米材料的膜，该膜可以接近理想的离子分离器性能，并有助于释放水性rfb在经济高效的储能方面的潜力。这一基础研究项目的发现将推动人们对纳米材料合成和离子在新膜中的传输行为的认识。该项目的多学科研究活动将为培养新兴能源技术和关键材料开发前沿的下一代科学家和工程师提供极好的机会。本项目将重点研究一种新型的二维沸石纳米片离子分离膜（ZNTM）。该项目将为二维纳米材料的合成和亚纳米孔二维纳米片膜新结构中的离子传输行为提供基础知识。无缺陷沸石膜，例如单晶，理论上能够在RFB操作中以高选择性和卓越的材料稳定性传导质子。然而，传统的混合基质沸石膜结构不能有效地实现这些良好的性能，因为金属离子通过快速的晶间空间交叉过多，而且膜的厚度相对较大，电阻也很高。该项目将解决二维离子筛晶体合成和性能裁剪的主要挑战，并通过新型ZNTM结构有效地利用其独特的性能。基础研究旨在确定合成纳米级沸石纳米片的条件，这些纳米片具有可控的表面化学、几何和尺寸特性（即足够大的宽厚长高比），以及在优选方向上的通道取向。系统的实验将建立一个有效的方法来制作超薄的二维ZNTM离子分离器。离子分离器的离子选择性、电导率和材料稳定性将被广泛研究，以了解它们对沸石纳米片和ZNTM的微观结构和表面化学的依赖。经过验证的离子选择性和最小电阻的ZNTM将在全电池RFB操作中进行评估，包括电池能效、功率密度、热稳定性和寿命。对新膜的评价将集中在工业上重要的全钒和离子铬RFB化学上。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.