Probing the Mechanism and Morphology of Magnesium Deposition from High Anodic Stability, High Solution Conductivity Electrolytes

探讨高阳极稳定性、高溶液电导率电解质的镁沉积机理和形貌

• 批准号: 1807687
• 负责人: Bart Bartlett
• 金额: $ 51.84万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1807687&HistoricalAwards=false
• 关键词: Probing; Mechanism; Morphology; Magnesium; Deposition

PART 1: NON-TECHNICAL SUMMARY Lithium batteries abound in the portable electronic devices that are toted daily. However, the scarcity and price of both lithium and the other metals used to create batteries provides the impetus to move beyond lithium-based technology. By virtue of its position in group I of the periodic table, lithium shuttles only one electron at a time between the two electrodes. With this project, funded by the Solid State and Materials Chemistry Program in the Division of Materials Research at NSF, the researchers at the University of Michigan Ann Arbor develop materials for magnesium ion batteries. Magnesium, a group II metal, can shuttle two electrons at a time. In principle, doubling the number of electrons that react at the electrodes doubles the amount of charge that can be stored in the same volume of space. Storing more charge with the same-sized battery represents a significant advance in energy storage for portable electronics and potentially for electric vehicles. Magnesium also has the potential to yield safer batteries since this metal is less reactive with air and moisture than is lithium. However, developing this technology requires learning what chemical reactions occur at the solid electrode/ liquid electrolyte interfaces of a battery and how these reactions change the electrode surface over time, which is the focus of this project. The goal is ensuring that both safety and high charge-storing capacity are maintained over the entire battery lifetime. In addition to the advancing scientific understanding, this project involves graduate students, undergraduate students, and high school students from diverse backgrounds who collaborate to combine different forms of spectroscopy and microscopy in order to interrogate what magnesium molecules form in liquid solution and to observe how these molecules transform to move electrons through lab-scale batteries. PART 2: TECHNICAL SUMMARY This project, funded by the Solid State and Materials Chemistry Program in the Division of Materials Research at NSF, addresses two critical questions at the anode/electrolyte interface using Lewis-acid salts of magnesium alkoxide electrolytes: 1) what are the structure and composition of matter at the electrode/electrolyte interface? 2) what are the size, shape, and distribution of defects at the electrode? To answer the first question, the researchers employ electrochemistry using polished platinum single crystals, solution NMR spectroscopy, and Raman microscopy to probe the electrolyte/bulk solution interface. To answer the second question, they rely on electron microscopy and scanning electrochemical microscopy to probe surface reconstruction as well as macroscopic changes in the morphology of the solid electrode under varied conditions. Although the lithium-ion battery field has demanded answers to these questions to develop this familiar technology, the chemistry of magnesium is quite different. One difference that is a major advantage for magnesium is that its hexagonal crystal structure leads to metal deposits in platelet form, not as dangerous dendritic wires that could short-circuit the battery. That said, the relationship between the salt composition (what ions are present and at what concentration) and the electrodeposition growth mechanism is unknown in magnesium. The first aspect of this research is composed of experiments to specify what ionic species reside at the electrochemical interface starting from the traditional Guoy-Chapman-Stern model of the electrochemical double layer (where excess charge accumulates adjacent to the electrode). With the second thrust, the researchers study how the atomic surface and the microstructure of magnesium and the underlying electrode change with continued cycling that includes potential adsorption/desorption of ions. Overall, this knowledge teaches the battery community to connect known electrolyte design principles to long-term high current (i.e.-high power) battery function.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.

第一部分： 锂电池大量存在于日常携带的便携式电子设备中。然而，锂和用于制造电池的其他金属的稀缺性和价格为超越锂基技术提供了动力。由于锂在元素周期表第I族中的位置，锂每次只能在两个电极之间穿梭一个电子。通过这个由NSF材料研究部的固态和材料化学计划资助的项目，密歇根大学安阿伯的研究人员开发了镁离子电池的材料。镁是第二族金属，一次可以穿梭两个电子。原则上，在电极上反应的电子数量增加一倍，可以存储在相同体积空间中的电荷量也会增加一倍。用同样大小的电池存储更多的电量，代表着便携式电子产品和电动汽车储能技术的重大进步。镁也有可能生产更安全的电池，因为这种金属与空气和水分的反应比锂少。然而，开发这项技术需要了解电池的固体电极/液体电解质界面发生了什么化学反应，以及这些反应如何随着时间的推移改变电极表面，这是该项目的重点。目标是确保在整个电池寿命期间保持安全性和高电荷存储容量。除了推进科学的理解，这个项目涉及研究生，本科生，和高中学生从不同的背景谁合作，以联合收割机不同形式的光谱和显微镜，以询问镁分子在液体溶液中形成，并观察这些分子如何转化为移动电子通过实验室规模的电池。第二部分： 该项目由NSF材料研究部的固态和材料化学计划资助，使用镁醇盐电解质的路易斯酸盐解决了阳极/电解质界面处的两个关键问题：1）电极/电解质界面处的物质的结构和组成是什么？2)电极上缺陷的大小、形状和分布是什么？为了回答第一个问题，研究人员采用电化学方法，使用抛光铂单晶，溶液NMR光谱和拉曼显微镜来探测电解质/本体溶液界面。为了回答第二个问题，他们依靠电子显微镜和扫描电化学显微镜来探测表面重建以及在不同条件下固体电极形态的宏观变化。尽管锂离子电池领域需要回答这些问题来开发这种熟悉的技术，但镁的化学性质却大不相同。镁的一个主要优势是，它的六方晶体结构导致金属沉积物以片状形式存在，而不是危险的树枝状电线，可能会使电池短路。也就是说，在镁中，盐组成（存在什么离子以及以什么浓度存在）和电沉积生长机制之间的关系是未知的。本研究的第一个方面是由实验来指定什么样的离子物种驻留在电化学界面从传统的Guoy-Chapman-Stern模型的电化学双层（其中过量的电荷积累相邻的电极）。通过第二个推力，研究人员研究了镁的原子表面和微观结构以及下面的电极如何随着持续的循环而变化，包括离子的潜在吸附/解吸。总的来说，这些知识教导电池界将已知的电解质设计原理与长期高电流（即，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。