CAREER: Design and Understanding up from the Atomic Scale of Multivalent Intercalation Electrodes for High-Energy-Density Rechargeable Batteries

迫切需要改进电动汽车的储能技术，并大规模整合可再生电网储能，以提高国内能源安全。目前，最先进的储能技术，如锂离子电池，能量密度不足，成本太高，无法在这些应用中广泛使用。基于多价离子(例如，铝离子或锌离子)的电池电极在电荷存储容量方面比单价(例如，锂离子)电极产生显著增强。当与其对应的金属电极配对时，可能会在能量密度方面产生潜在的变革性收益。然而，到目前为止，多价电池的性能仍然不足，这在很大程度上是因为对电极在连续的充放电循环中经历的复杂的电子、化学和结构变化的基本了解和控制有限。该项目的研究工作将研究在使用多价电极时发生的基本电化学过程，从而为如何设计和实现具有显著增强的储能性能的可充电电池提供见解。可充电的铝离子和锌离子电极将被研究，因为铝和锌金属都是富含稀土的，低成本，非易燃，无毒，并表现出高体积电荷存储能力。该项目还包括通过“电池训练营”与当地一所高中的高中理科教师直接互动，推动高中阶段的STEM教育的外联工作。外展将强调共同开发动手的、适合高中生年龄的实验室实验，以帮助理解电化学工程的概念。该项目还将在纽约市立大学(CUNY)内为研究生举办一所核磁共振学院，以结合这项技术和其他先进的光谱方法来丰富他们各自的研究项目。该研究项目的科学和技术目标是：(I)从原子尺度上了解晶体过渡金属化合物中多价阳离子电化学插层的过程和性质，以及(Ii)利用这一理解来发现和优化具有显著增强的体能存储性能的新型插层电极。为了利用铝和锌金属良好的电化学性质，同时研究不同的离子价态和电荷密度的影响，我们将研究铝离子(Al3+)和锌离子(Zn2+)的嵌入电极。模型过渡金属化合物的电子结构和晶体结构将发生系统的变化，从而能够从分子水平到细胞水平研究它们与电化学插层现象的关系。随后，将利用从模型研究中获得的知识来启动有针对性的材料发现工作，其中将为下一代铝离子和锌离子电池合成和探索新的电极成分和结构。新颖的多维固体核磁共振方法将对插层阳离子和电极骨架的原子水平环境、结构和动力学产生新的见解，揭示离子插层和电荷转移机制。总体而言，这项工作预计将建立和验证分子设计原则，旨在实现具有增强的电荷存储能力、嵌入电位和速率特性的多价嵌入电极。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

There is a critical need for improved energy storage technologies for electric vehicles and large-scale integration of renewable electricity grid storage to improve domestic energy security. Currently, state-of-the-art energy storage technologies such as lithium-ion batteries have insufficient energy density and are too costly for broad use in these applications. Battery electrodes based on multivalent ions (e.g., aluminum ions or zinc ions) yield significant enhancements in electric charge storage capacity over monovalent (e.g., lithium-ion) electrodes. When paired with their corresponding metal electrodes, potentially transformative gains in energy density are possible. However, multivalent battery performance to date is lacking, in large part due to limited fundamental understanding and control of the complex electronic, chemical, and structural changes that the electrodes undergo upon continued charge and discharge cycles. Research efforts in this project will investigate the fundamental electrochemical processes that occur during the use of multivalent electrodes, yielding insights into how to design and realize rechargeable batteries with significantly enhanced energy storage properties. Rechargeable aluminum-ion and zinc-ion electrodes will be investigated as both aluminum and zinc metals are earth abundant, low-cost, non-flammable, non-toxic, and exhibit high volumetric charge storage capacity. The project also includes outreach efforts that will advance STEM education at the high school level by directly interacting with high school science teachers at a local high school via a "Battery Bootcamp". Outreach will stress the co-development of hands-on, age appropriate laboratory experiments for the high school students to use to help understand electrochemical engineering concepts. The project also will conduct a NMR School within the City University of New York (CUNY) for graduate students to incorporate this technique and other advanced spectroscopic methods to enrich their own respective research projects.The scientific and technological objectives of this research project are to (i) understand, up from the atomic scale, the processes and properties underpinning electrochemical intercalation of multivalent cations in crystalline transition metal compounds and (ii) to use this understanding to discover and optimize novel intercalation electrodes with significantly enhanced bulk energy storage properties. Aluminum-ion (Al3+) and zinc-ion (Zn2+) intercalation electrodes will be investigated to leverage the favorable electrochemical properties of aluminum and zinc metal while enabling the effects of differing ion valence and charge density to be studied. The electronic and crystalline structures of model transition metal compounds will be systematically varied, enabling investigations of their relationships to electrochemical intercalation phenomena from the molecular to the cell level. Subsequently, knowledge gained from model studies will be used to initiate targeted materials discovery efforts, wherein new electrode compositions and structures will be synthesized and explored for next-generation aluminum-ion and zinc-ion batteries. Novel multi-dimensional solid-state nuclear magnetic resonance (NMR) methods will yield new insights into the atomic-level environments, structures, and dynamics of intercalated cations and electrode frameworks, revealing ion intercalation and charge transfer mechanisms. Overall, this work is expected to establish and validate molecular design principles aimed at realizing multivalent intercalation electrodes with enhanced charge storage capacities, intercalation potentials, and rate properties.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.