Unveiling relationships between synthesis, structure and nonaqueous ion cycling in chemically preintercalated layered oxides

第一部分：非技术总结依赖于便携式自主电源的应用种类不断扩大，这对发现创新材料提出了挑战，这些材料可用作电解质中含有锂和更便宜的钠和钾离子的电池的高容量电极。该解决方案由具有大的层间区域的水合层状氧化物提供，例如双层钒氧化物（BVO）。这项研究由NSF材料研究部的固态和材料化学计划资助，通过低温湿化学合成路线利用可控的BVO制备，该路线在Pomerantseva教授的实验室中开发，称为化学预插层，将特定量的各种离子和分子纳入材料结构的层间区域。的结构参数，改善运输的电化学循环离子和增强的结构稳定性揭示导致先进的电化学性能。该研究为电极材料的设计提供了必要的信息，以实现具有高能量密度和长循环寿命的下一代储能系统。从这项研究中获得的基本新知识还推动了基于离子可逆循环的新兴应用，超越了能量存储，如传感，驱动，离子可调非易失性存储器和电致变色。该项目为高年级本科生和研究生提供了一个跨学科技能的平台。这些教育和推广工作丰富了PI机构的本科生和研究生课程，提高了妇女对科学和工程的参与，并通过开发新的嵌入反应演示，向大学预科生介绍了储能技术。本项目由NSF材料研究部的固态和材料化学计划支持，开发策略以减轻高容量亚稳水合层状插入氧化物的性能退化，其具有在由结构不稳定性引起的延长的电化学循环期间扩展的中间层区域。该研究项目的目标是提供一个基本的了解如何层间物种的性质和数量影响这一系列材料的结构和储能性能。双层钒氧化物（BVOs），表现出独特的化学多功能性的层间区域，作为模型材料系统。互补X射线和中子对分布函数分析用于确定BVO结构中所有原子的位置，以建立结构-性质相关性。该目标是通过测试的假设，即层间物种定义的扩散路径和电荷存储的机制，不仅形成一定的安排，在层间区域，但也指导V-O层的形成和层内结构。该假说由三部分组成，并在本项目中得到了验证：（1）化学预插层无机离子的性质和数量决定了V-O层的结构，从而影响电化学循环离子的扩散;（2）层间水分子有助于为电化学循环离子创造插层位点和扩散路径，并且其浓度可以控制在一定值，使层状结构稳定，使引起性能下降的寄生反应最小化;（3）通过化学预插层多功能有机物质，可以实现双层钒氧化物的结构和电荷存储性能的进一步可调性。本研究的最终目的是确定夹层区域的化学组成与双层钒氧化物的结构之间的相关性，并建立导致电化学循环离子的促进扩散和非水锂离子中电极的增强的结构和电化学稳定性的参数，钠离子和钾离子嵌入电池。该奖项反映了NSF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。

PART 1: NON-TECHNICAL SUMMARYThe expanding variety of applications relying on portable autonomous power sets a challenge for the discovery of innovative materials to be used as high-capacity electrodes in batteries with lithium and more affordable sodium and potassium ions in electrolytes. The solution is offered by hydrated layered oxides with a large interlayer region, such as bilayered vanadium oxides (BVOs). This research, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, exploits controllable BVOs preparation via a low-temperature wet-chemical synthesis route, developed in the Prof. Pomerantseva’s laboratory and called chemical preintercalation, to incorporate specific amounts of various ions and molecules into the interlayer region of material structure. The structure parameters governing improved transport of electrochemically cycled ions and enhanced structural stability are revealed leading to advanced electrochemical properties. This research provides necessary information for the design of electrode materials to enable next-generation energy storage systems with high energy density and long cycle life. The fundamental new knowledge gained from this study also advances emerging applications based on reversible cycling of ions beyond energy storage, such as sensing, actuation, ion-tunable non-volatile memory and electrochromics. This project provides a platform to equip senior undergraduate and graduate students with interdisciplinary skills. The educational and outreach efforts enrich undergraduate and graduate curricula at the PI’s institution, enhance women’s involvement in science and engineering, and introduce pre-college students to energy storage technology through the development of a new intercalation reaction demonstration.PART 2: TECHNICAL SUMMARYThis project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, develops strategies to alleviate performance degradation of high-capacity metastable hydrated layered insertion oxides with an expanded interlayer region over extended electrochemical cycling caused by structural instability. The goal of this research project is to provide a fundamental understanding of how the nature and amount of interlayer species affect the structure and energy storage properties of this family of materials. Bilayered vanadium oxides (BVOs), which demonstrate unique chemical versatility of the interlayer region, serve as the model material system. Complimentary X-ray and neutron pair distribution function analysis is used to determine the positions of all atoms in the structure of BVOs to establish structure – property correlations. The goal is achieved by testing the hypothesis that interlayer species define diffusion pathways and mechanism of charge storage by not only forming certain arrangements in the interlayer region but also directing the formation and intralayer structure of V-O layers. The hypothesis consists of three parts, each of which is tested in the project: (1) The nature and amount of chemically preintercalated inorganic ions determine the structure of V-O layers, thus affecting diffusion of electrochemically cycled ion; (2) Interlayer water molecules contribute to creating intercalation sites and diffusion paths for electrochemically cycled ions and their concentration can be controlled at certain value, enabling stability of layered structure with minimized parasitic reactions which cause performance degradation; (3) Further tunability of the structure and charge storage properties of bilayered vanadium oxides can be achieved via chemical preintercalation of versatile organic species. The ultimate aim of this research is to determine correlations between chemical composition of the interlayer region and the structure of bilayered vanadium oxides and to establish parameters that lead to facilitated diffusion of electrochemically cycled ions and enhanced structural and electrochemical stability of the electrodes in nonaqueous Li-ion, Na-ion and K-ion intercalation batteries.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.