Using Electrodeposition to Understand the Effects of Composition and Element Segregation on the Physical Properties of Anodes for High Energy-Density Rechargeable Batteries

能源转换和储存技术对现代社会的运行、维护和发展至关重要。美国现在每年生产超过25太瓦时的电力，其中绝大多数是由煤炭，天然气和石油等不可再生燃料提供的。因此，开发比现有技术更有效的新技术，或帮助现有技术更有效地使用能源的技术，对我们的未来至关重要。在过去的几十年里，很明显，储能设备是各种拟议技术的关键组成部分。技术要求根据每个所需应用的具体限制而显著变化，因此需要广泛的功能材料，化学物质和架构，可用于构建目标和特定的能量存储设备。该研究由固态和材料化学计划资助，重点是开发无毒，廉价的三种潜在阳极材料的制造方法，这些材料可用于锂和钠可充电电池。 这些材料是已知的，但它们如何降解（以及为什么降解）还不清楚。 了解这些材料的工作原理以及它们的主要局限性是本研究的主要目标。这是找出如何延长这些材料的寿命从而延长电池寿命的关键的第一步。这个固态和材料化学奖还使主要研究人员能够开展与她的研究有关的外联活动，涉及所有年级的学生以及公众和政策制定者。例如，科罗拉多州立大学的“化学俱乐部”吸引了小学生，高中生在研究实验室接受主要研究者和她的学生的指导，主要研究者在当地俱乐部邀请关于科学的演讲，她是科罗拉多清洁能源集群的董事会成员，直接影响科罗拉多的政策。技术概述存储大量锂并在电解质的电化学电势范围的极端处可逆地操作的电池材料能够实现高电压和高能量密度的电池单元。在可用的候选材料中，元素合金材料如锑和相关的锑化物具有特别高的体积容量，并且在接近锂金属电镀的电势下操作，从而允许高的理论能量密度。然而，由于在循环期间它们的体积变化大，它们的可逆性低，并且表面钝化差，这导致阳极表面处的电解质显著降解和随后的电池阻抗上升。本工作开发了用于生产碱金属离子（锂和钠）可充电电池的低成本、高性能阳极的直接电沉积方法。使用电沉积的优点是可以控制材料的组成和形态，并且完全消除了非活性粘合剂（这极大地有助于功能材料的表征）。研究奋进涉及直接合成三种关键锑化物（镍，铜，锌和氨基化合物）的电沉积薄膜和纳米结构的策略，并对其进行充分表征，以更深入地了解作为组成函数发生的锂化和脱锂反应，以及这些反应如何导致降解和最终电池故障。在循环过程中观察薄膜的相形成和元素组成进一步有助于开发这些材料如何工作，如何降解的清晰模型，并最终开发如何延长循环寿命和实用性的假设。主要调查员还利用这笔赠款开展各种教育和外联活动。除了在干相关活动的各个年级的学生参与，她还通过邀请在当地俱乐部的科学讲座，并作为科罗拉多清洁能源集群，这有助于影响政策的董事会成员直接向公众传达她的研究结果在科罗拉多有关清洁技术公司的经济发展。

PART 1:  NON-TECHNICAL SUMMARYEnergy conversion and storage technology is critical to the operation, maintenance, and development of modern society. The United States now produces over 25 terawatt hours of electricity per year, with the vast majority being provided by non-renewable fuels such as coal, natural gas, and oil. Developing new technologies that are more efficient than existing ones, or technologies that help existing technologies use energy more efficiently, is therefore critical to our future. Over the last few decades, it has become clear that energy storage devices are a key component in a wide range of proposed technologies. The technical requirements vary dramatically based on the specific constraints of each desired application, and as such there is need for a wide range of functional materials, chemistries, and architectures that can be used to build targeted and specific energy storage devices. The research, funded by the Solid State and Materials Chemistry program, focuses on developing non-toxic, inexpensive manufacturing methods for three potential anode materials that could be used in lithium and sodium rechargeable batteries. These materials are known, but how they degrade (and why) is not. Understanding how these materials work and what their key limitations are is the main goal of this study. This is the critical first step toward finding out how to extend the life of these materials and thereby the life of batteries. This Solid State and Materials Chemistry award furthermore enables the principle investigator to conduct outreach activities related to her research involving students at all grade levels as well as the general public and policymakers. For example, the CSU 'Chemistry Club' engages elementary school students, high school students are mentored by the principle investigator and her students in the research lab, the principle investigator gives invited talks about science at local clubs, and she is a board member of the Colorado Clean Energy Cluster, which impacts policy in Colorado directly.PART 2:  TECHNICAL SUMMARYBattery materials that store large amounts of lithium and operate reversibly at the extreme ends of the electrochemical potential range of electrolytes enable high voltage and high energy density battery cells. Among available candidates, elemental alloying materials such antimony and related antimonides possess exceptionally high volumetric capacities and operate at potentials close to the plating of lithium metal, allowing for high theoretical energy density. Nevertheless, they suffer from low reversibility as a result of large changes in their volume during cycling, and poor surface passivation that causes significant degradation of the electrolyte at the anode surface and a subsequent rise in the cell impedance. This work develops direct electrodeposition methods for producing low-cost, high-performance anodes for alkali metal ion (lithium and sodium) rechargeable batteries. The advantage of using electrodeposition is that the composition and morphology of the material can be controlled, and inactive binders are completely eliminated (which greatly aides in the characterization of the functional materials). The research endeavor involves a strategy of synthesizing directly electrodeposited thin films and nanostructures of three key antimonides (nickel, copper, and zinc and animonide) and characterizing them fully to develop a deeper understanding of the lithiation and delithiation reactions that occur as a function of composition, and how these reactions may lead to degradation and ultimately cell failure. Observing the phase formation and elemental composition across films during cycling further aids in the development of a clear model of how these materials work, how they degrade, and ultimately, the development of hypotheses for how to extend cycle life and utility. With this grant the principle investigator also conducts a variety of educational and outreach activities. Besides engaging students at all grade levels in STEM-related activities, she also communicates her findings directly to the general public through invited talks about science at local clubs and as a board member of the Colorado Clean Energy Cluster, which serves to impact policy in Colorado related to the economic development of clean tech companies.