Collaborative Research: Elucidating Correlations Between Solvation Structure and Electrochemical Behavior of Water-in-Salt Electrolytes for Highly Reversible Zinc Metal Anode

来自风能和太阳能的可再生能源为减少温室气体排放及其对气候变化的影响提供了解决方案。不幸的是，可以从这些可再生能源产生的电力是间歇性的，并且通常与电能需求异步。因此，大规模储能对于减少对化石燃料依赖的可持续经济是必不可少的。水性锌（Zn）金属电池代表了这种能量存储需求的有前途的解决方案，可以以低成本存储能量，具有低环境足迹和高本质安全性。然而，Zn金属电池的循环寿命短，这主要是由于Zn金属阳极被水腐蚀。这种腐蚀大大缩短了锌金属电池的循环寿命，并由于产生爆炸性氢气而引起安全问题-这两个挑战需要开箱即用的解决方案。最近出现的高度浓缩的“盐包水”电解质提供了重新定义Zn金属阳极和水性电解质之间的稳定性的独特机会。该项目旨在改变水溶性锌金属电池的循环稳定性并提高其安全运行。如果成功，这将标志着美国储能技术的重大突破。对于教育影响，调查人员将利用他们的大学的机构计划，以增加社区大学生和高中生在夏季研究经验的参与。该项目将通过整合材料电化学、飞秒拉曼光谱和从头计算等领域的研究活动，阐明高浓度溶液中的水稳定性。这些互补的方法具有高度的协同作用，从不同的Vantage位置提供见解，当整合时可以实现深入的理解。在研究的浓电解质中，每个溶剂化离子的水分子很少;因此，与标准稀释溶液相比，溶剂化鞘通常更薄或不完整。这样的溶剂化结构显著地改变溶剂化离子和作为溶剂的动态水分子的性质。初步结果表明，水分子对析氢表现出异常高的电化学稳定性，并在受激拉曼研究中显示出有趣的振动频率蓝移。第一性原理计算表明，在这些浓溶液中存在水分子的特殊性质。该项目将深入了解浓缩电解质的溶剂化结构与与锌金属阳极接触的相应稳定性之间的相关性。这些知识的价值将超越物理科学和工程的不同学科，并影响学术和工业环境中广泛的STEM学习者和从业者。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Renewable energy from wind energy and solar power offers a solution to reducing greenhouse gas emissions and their impact on climate change. Unfortunately, the power that can be generated from these renewable sources is intermittent and typically asynchronous with electrical energy demand. Thus, large-scale energy storage is indispensable for a sustainable economy with reduced reliance on fossil fuels. Representing a promising solution to this energy storage need, aqueous zinc (Zn) metal batteries can store energy at a low cost, with low environmental footprint and high intrinsic safety. However, Zn metal batteries suffer from short cycle life, primarily due to corrosion of the Zn metal anode by water. This corrosion drastically curtails the cycle life of Zn metal batteries and causes a safety concern due to the generation of explosive hydrogen gas—two challenges that require outside-the-box solutions. The recent emergence of highly concentrated “water-in-salt” electrolytes offers a unique opportunity to re-define the stability between the Zn metal anode and the aqueous electrolyte. This project seeks to transform the cyclic stability and increase safe operation of aqueous Zn metal batteries. If successful, this will mark a significant breakthrough for energy storage technologies in the United States. For educational impacts, the investigators will leverage institutional programs their universities to increase the participation of community college students and high school students in summer research experiences. The training of graduate and undergraduate students will feed the workforce need of the next-generation energy sector.The project will elucidate the water stability properties in extremely concentrated solutions by integrating research activities in materials electrochemistry, femtosecond Raman spectroscopy, and ab initio computation. These complementary methods are highly synergistic, providing insights from different vantage points that when integrated can enable deep understanding. In the concentrated electrolytes of study there are few water molecules per solvated ion; therefore, the solvation sheaths are often thinner or incomplete compared to standard dilute solutions. Such solvation structures significantly alter the properties of the solvated ions and the dynamic water molecules as a solvent. Preliminary results have revealed that water molecules exhibit unusually high electrochemical stability against hydrogen evolution and display an intriguing blueshift of vibrational frequencies in stimulated Raman studies. First-principles calculations indicate that there exist peculiar properties of water molecules to be explored in these concentrated solutions. This project will generate an in-depth understanding of the correlation between solvation structures of the concentrated electrolytes and the corresponding stability in contact with the Zn metal anode. The values of such knowledge will transcend different disciplines of physical sciences and engineering and impact a broad range of STEM learners and practitioners in academic and industrial settings.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.