Advanced Electrochemistry of Na-ion Battery Cathodes Through Chemically Controlled Materials Synthesis

嵌入反应是锂离子电池工作机制的核心，锂离子电池仍然是便携式电子产品和电动汽车最常用的储能装置。插层通常是可逆过程，其涉及将客体物质引入主体电极材料中。认识到锂是一种有限的资源，这可能导致锂离子电池的成本显著增加，已经将研究方向转向研究替代嵌入系统，例如钠离子电池。然而，与锂离子相比，更大的尺寸和更高的重量限制了钠离子通过普通电极材料的嵌入和扩散。这导致显著的电极劣化（从而导致第一次循环后的容量损失和循环寿命降低）和在高电流速率下操作的限制。在材料研究部门的固态和材料化学计划的支持下，该项目的重点是通过化学预嵌入特定类型和数量的无机离子来解决这些缺点。拟议的工作有可能开发可用于取代当前锂离子电池的钠离子电池阴极，提供更便宜，可靠和环保的可持续能源存储，有助于开发下一代能源存储系统用于运输，电网存储和其他可再生能源应用。该项目提供了一个很好的机会，让高年级本科生和研究生参与材料科学与工程领域的硕士和博士研究，并对材料化学和电化学产生更广泛的影响。首席研究员计划将这项研究的结果整合到储能应用材料的课程中。该项目通过在国家/国际会议上的演讲、参考期刊出版物和科学活动中的演示，加强了知识向广泛的研究团体和公众的传播。技术摘要化学预插层是一种湿化学方法，其中无机离子在溶液中插入电极材料的晶体结构中，随后形成凝胶和/或溶胶，或另一种形式的沉淀物，其中无机离子被“捕获”在固体材料的结构中。这项研究的目的是测试以下假设：通过引入特定类型和量的化学预插层离子，可以在钠离子电池电极中实现高容量，长循环寿命和高功率，这使得材料具有高比容量，增强的结构稳定性和快速离子扩散。选择具有丰富的晶体化学、结构柔性和形态结构的氧化钒作为化学预插层的主体结构。该项目旨在系统地了解钠离子电池中化学预插层钒氧化物电极的合成-结构-性能关系。通过循环伏安法、恒流充放电循环、倍率性能实验和阻抗谱测量来评价合成材料的电化学性能。研究小组计划确定合成参数的变化如何影响电化学性能，旨在了解与材料化学和结构相关的基本现象，这些现象可能导致更大量的存储电荷，更快的离子和电子传输以及钠离子可逆循环期间的优异稳定性。

Non-Technical AbstractIntercalation reactions lie at the heart of the operation mechanism of lithium-ion battery, which remains the most used energy storage device for portable electronics and electric cars. Intercalation is usually a reversible process that involves the introduction of a guest species into a host electrode material. The realization that lithium is a limited resource, which potentially can result in a significant increase in the cost of lithium-ion batteries, has shifted research directions towards investigation of alternate intercalation systems, such as sodium-ion batteries. However the larger size and higher weight limits intercalation and diffusion of sodium ions through common electrode materials, compared to lithium ion. This results in significant electrode degradation (thereby resulting in capacity loss after the first cycle and reduced cycle life) and limitations in operation at high current rates. With support from the Solid State and Materials Chemistry program of the Division of Materials Research, this project focuses on addressing these shortcomings through chemical pre-intercalation of the specific types and amounts of inorganic ions. The proposed work has the potential to enable the development of sodium-ion battery cathodes that can be used to replace current lithium-ion batteries, providing sustainable energy storage that is cheaper, reliable, and environmentally friendly, contributing to the development of next-generation energy storage systems for transportation, grid-storage and other renewable energy applications. The project offers an excellent opportunity to engage senior undergraduate and graduate students in masters and doctoral-level research in the field of Materials Science and Engineering and its broader impact on Materials Chemistry and Electrochemistry. The principal investigator plans to integrate the results of this research in the course on materials for energy storage applications. This project enhances the dissemination of knowledge to a broad research community and general public through presentations at National/International conferences, refereed journal publications and demonstrations at science events.Technical AbstractChemical pre-intercalation is a wet chemistry approach, in which the inorganic ions are inserted into the crystal structure of the electrode material in a solution followed by the formation of a gel and/or sol, or another form of a precipitate, with inorganic ions being 'trapped' in the structure of a solid material. The goal of this proposed research is to test the hypothesis that high capacity, long cycle life and high power can be achieved in Na-ion battery electrodes by introducing specific types and amounts of chemically pre-intercalated ions, which enables materials with high specific capacity, enhanced structural stability and fast ionic diffusion. Vanadium oxide, a material with rich crystal chemistry, structural flexibility and morphological architectures, is chosen as a host structure for chemical pre-intercalation. The project seeks a systematic understanding of synthesis - structure - performance relationships for chemically pre-intercalated vanadium oxide electrodes in Na-ion batteries. Electrochemical properties of the synthesized materials are evaluated by cyclic voltammetry, galvanostatic discharge/charge cycling, rate capability experiments and impedance spectroscopy measurements. The research team plans to determine how changes in the synthesis parameters affect electrochemical performance with the aim to understand fundamental phenomena related to materials chemistry and structure that may lead to larger amount of the stored charge, faster ion and electron transport, and excellent stability during reversible cycling of sodium ions.