EAGER: Polymer Sponge Electrodes for Energy-Efficient Desalination

目前的海水淡化技术是能源密集型和昂贵的，限制了我们为不断增加的全球人口生产清洁水的能力。近年来，研究人员探索了一种新的概念，该概念基于使用类似电池的设备从海水中去除盐，盐水流入设备，盐离子与设备内的电极结合，淡水流出。人们期望这种称为电容去离子（CDI）的技术通过电极放电回收输入能量（类似于电池的充电和放电）来最大限度地提高脱盐的能源效率。然而，CDI装置的性能对于海水淡化来说还没有竞争力。密苏里州大学的研究人员将致力于了解CDI电极用于海水淡化的不良性能的根源，并克服这些限制以提高CDI的能源效率。研究人员将分离并独立研究被认为导致CDI效率低下的两个主要因素--离子吸收能力低和CDI电极内离子传输缓慢。结合大量离子的导电涂层将用于控制电极的离子吸收能力，而柔软的可压缩电极基质将用于在充电期间使用机械压缩来控制电极内的离子传输速率。这项工作将填补理解电极设计方面如何与物理过程相结合以推动CDI性能的关键空白。该项目将建立一种新的CDI电极模式，该模式集成了高速、法拉第表面反应，用于在柔软、可压缩的海绵基底内快速吸收离子，通过海绵的机械压缩在CDI电极内快速传输离子。为了产生这些电极，研究人员将采用已建立的分子层沉积（MLD）化学方法，使用气相前体的顺序反应，将微孔聚氨酯（PU）泡沫与导电和氧化还原活性聚乙烯二氧噻吩（PEDOT）涂层结合起来。该项目将（1）研究关键的合成方面，使可压缩的CDI电极的制造和（2）基准什么水平的CDI效率可以从可压缩的电极提供。研究人员将研究PEDOT厚度、泡沫空隙体积和压缩率对离子吸收能量效率的影响。这项工作将帮助研究人员了解和克服限制现有CDI电极性能的障碍，有可能使CDI超越当前的海水淡化技术，并提供低成本的清洁水，以帮助解决全球水资源短缺问题。该奖项反映了NSF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。

Current seawater desalination technology is energy-intensive and costly, limiting our ability to generate clean water for an increasing global population. In recent years, researchers have explored a new concept based on the removal of salt from seawater using a battery-like device where salt water flows into the device, salt ions bind to electrodes within the device, and fresh water flows out. One would expect this technology, called capacitive deionization (CDI), to maximize the energy efficiency of desalination by recovering input energy through discharge of the electrodes—similar to charging and discharging a battery. However, the performance of CDI devices has not yet been competitive for seawater desalination. Researchers at the University of Missouri will work to understand the origins of the poor performance of CDI electrodes for seawater desalination and overcome these limitations to boost the energy efficiency of CDI. The investigators will decouple and independently study the two main factors thought to drive CDI inefficiency – low ion uptake capacity and slow ion transport within CDI electrodes. Electrically conductive coatings that bind large amounts of ions will be used to control the ion uptake capacity of electrodes, while a soft, compressible electrode matrix will be used to control the rate of ion transport within the electrodes using mechanical compression during charging. This work will fill a critical gap in understanding how electrode design aspects are coupled with physical processes to drive CDI performance. The outcomes of this project will define the most promising avenues for investigation in pursuit of the next generation of desalination technology.This project will establish a new modality of CDI electrode that integrates high-rate, faradaic surface reactions for rapid ion uptake within a soft, compressible sponge substrate for rapid ion transport within the CDI electrode through mechanical compression of the sponge. To generate these electrodes, researchers will employ established molecular layer deposition (MLD) chemistry using sequential reaction of gas-phase precursors to impregnate microporous polyurethane (PU) foams with electrically-conductive and redox-active polyethylenedioxythiophene (PEDOT) coatings. The project will (1) study key synthesis aspects enabling the fabrication of compressible CDI electrodes and (2) benchmark what level of CDI efficiency can be delivered from compressible electrodes. Researchers will study the impact of PEDOT thickness, foam void volume, and compression rate on the energy efficiency of ion uptake. This work will help researchers understand and overcome the barriers limiting the performance of existing CDI electrodes, potentially enabling CDI to outperform current seawater desalination technology and providing low-cost, clean water to help address global water scarcity.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.