Collaborative Research: Probing and Tailoring the Cathode-Electrolyte Interfacial Chemistries for Sodium Ion 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，锂离子电池等最先进的储能技术不足以满足广泛使用所需的性能要求，如成本和能量密度。替代电池化学可以为这些应用提供一条在能量密度、耐用性和成本方面获得收益的途径。这一基础研究项目致力于将钠离子电池作为一种潜在的、低成本和可持续的解决方案来应用于大规模的电化学储能系统。然而，这类电池的正极材料循环寿命较低，这是实现商业化的重要障碍。该项目通过一个协作实验计划来解决这个问题，该计划侧重于阴极材料的合成方法和实验表征工具，这些工具可以测量在阴极和电池电解液的界面区域发生的过程。基础知识将导致这些过程，并将使合理的设计战略，以增加耐用性，能量密度，和循环寿命的这一类型的电池。为了产生更广泛的影响，该项目的合作伙伴将在杰克逊州立大学建立一个能源储存研究项目。将通过夏令营和学习中心丰富每个项目机构的外联方案，为有阅读障碍的小学生提供教育单元和动手活动，并加强家长的参与。本项目旨在阐明钠离子电池正极材料的界面退化机理，并建立调整和强化钠离子电池正极-电解液界面的实验方法。该项目将利用先进的同步加速器X射线和电子表征工具来探测时间和空间分辨环境中的电池化学。该项目将改善活性粒子的电化学动力学和正极材料的表面稳定性，从而提高其在钠离子电池中的性能。有必要进行全面的研究，以了解界面退化的形成和演化，并定量地确定其与表面氧反应性和整体氧化还原化学的关系。掺杂方法将同时减缓界面退化和加速体电化学动力学。该研究将完成以下目标：(1)探索多尺度的界面化学和结构变化，并研究钠阴极表面化学、界面降解和电化学动力学之间的关系；(2)进行光谱和成像测量，以空间量化界面退化对钠阴极颗粒整体氧化还原行为的影响，作为荷电状态、循环历史和充电方案的函数；以及(3)建立调整阴极表面化学的方法，以减轻界面退化并改善钠离子电池的性能(例如能量密度、循环寿命、这一奖项反映了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 are insufficient in providing the performance requirements needed such as cost and energy density to enable broad use. Alternative battery chemistries could provide an avenue towards gains in energy density, durability, and cost for these applications. This fundamental research project addresses the use of sodium ion batteries as a potential low-cost and sustainable solution to large-scale electrochemical energy storage systems. However, the inferior cycle life of cathode electrode materials for this type of battery is a significant roadblock towards commercialization. This project addresses the issue with a collaborative experimental program that focuses on cathode electrode material synthesis methods and experimental characterization tools that can measure the processes occurring at the interface region of the cathode electrode and the battery electrolyte. Fundamental knowledge will result on these processes and will enable rational design strategies to increase the durability, energy density, and cycle life of this battery type. For broader impacts, the project's partners will establish an energy storage research program at Jackson State University. An outreach program at each project institution will be enriched with educational modules and hands on activities for elementary school-age students with a learning disability in dyslexia via summer camps and learning centers and with enhanced parent participation. This project seeks to elucidate the interfacial degradation mechanisms of sodium cathode materials and to establish experimental approaches for tailoring and strengthening the cathode?electrolyte interface for sodium-ion batteries. The project will make use of advanced synchrotron X-ray and electron characterization tools to probe the battery chemistry in the temporally and spatially resolved environments. The project will improve the electrochemical kinetics of active particles and surface stability of cathode materials and thus their performance in sodium ion batteries. There is a need for a holistic study to understand the formation and evolution of the interfacial degradation as well as to quantitatively pinpoint its relationship with the surface oxygen reactivity and bulk redox chemistry. The doping approach will simultaneously mitigate the interfacial degradation and accelerate the bulk electrochemical kinetics. The research will accomplish the following objectives: (1) probing the multiscale interfacial chemical and structural transformations and investigating the relationship between sodium cathode surface chemistry, interfacial degradation, and electrochemical kinetics, (2) conducting spectroscopic and imaging measurements to spatially quantify the influence of the interfacial degradation on the bulk redox behavior of sodium cathode particles as a function of the state-of-charge, cycling history, and charging protocol, and (3) establishing approaches to tailor the cathode surface chemistry for mitigating the interfacial degradation and improving the sodium ion battery performance (e.g. energy density, cycle life, rate capability).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.