Collaborative Research: Probing and Tailoring the Cathode-Electrolyte Interfacial Chemistries for Sodium Ion Batteries

提高电动汽车的储能技术和可再生能源电网储能的大规模集成是提高国内能源安全的迫切需要。目前，锂离子电池等最先进的储能技术还不足以满足广泛使用所需的成本和能量密度等性能要求。替代电池化学物质可以为这些应用提供能量密度、耐用性和成本方面的收益。这个基础研究项目解决了钠离子电池作为大规模电化学储能系统的潜在低成本和可持续解决方案的使用。然而，这种类型的电池的阴极电极材料较差的循环寿命是迈向商业化的一个重要障碍。该项目通过一个合作实验项目来解决这个问题，该项目专注于阴极电极材料合成方法和实验表征工具，这些工具可以测量阴极电极和电池电解质界面区域发生的过程。这些过程的基础知识将使合理的设计策略能够提高这种类型电池的耐用性、能量密度和循环寿命。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存储研究项目。每个项目机构的外展计划将通过夏令营和学习中心为有阅读障碍的小学适龄学生提供丰富的教育模块和实践活动，并加强家长的参与。本项目旨在阐明钠阴极材料的界面降解机制，并建立定制和强化阴极的实验方法。钠离子电池的电解液界面。该项目将利用先进的同步加速器x射线和电子表征工具，在时间和空间分辨的环境中探测电池化学。该项目将提高活性颗粒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。有必要对界面降解的形成和演化进行全面的研究，并定量地确定其与表面氧反应性和本体氧化还原化学的关系。掺杂方法可以同时减轻界面降解和加速本体电化学动力学。本研究将达到以下目标：(1)探索多尺度界面化学和结构转变，研究阴极钠表面化学、界面降解和电化学动力学之间的关系；(2)通过光谱和成像测量，在空间上量化界面降解对阴极钠颗粒氧化还原行为的影响，作为电荷状态、循环历史和充电方案的函数；(3)建立定制阴极表面化学的方法，以减轻界面退化，提高钠离子电池的性能（如能量密度、循环寿命、倍率能力）。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。

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.