EAGER: Investigation of Lithium-Air Battery Cathode Reaction Mechanisms through SERS-Active Electrode

该项目旨在开发用于电动汽车的锂空气电池，作为化石燃料汽车的替代品。为了与商用内燃机竞争，电力存储系统必须在能量密度、功率密度和可逆性方面得到显著改善。锂空气电池具有显著提高能量密度的潜力，但它们仍然不成熟，并且存在许多问题，包括它们具有缓慢且不可逆的阴极反应。由于锂空气电池的阴极反应机理尚不清楚，因此很难设计出更好循环的电极和电解质。本研究的主要目的是合成一种双连续、表面增强拉曼光谱（SERS）活性锂空气电池电极，并利用拉曼光谱研究锂空气电池充放电过程的机理。这是一项EAGER拨款，用于证明制造过程的可行性。智力优势：本项目旨在制造sers活性电极，以研究阴极上形成的产品。制造组织良好的双连续三维多孔电极的基本原理是同时提供更大的有效表面积，并改善电解质和氧气的扩散。锂空气电池正极反应复杂且对局部电化学环境敏感。研究电池电极反应的机理对于获取电池充放电过程中电极的化学信息具有重要意义。在这项工作中，PI计划使用聚合物模板来制造由原始化学气相沉积石墨烯制成的组织良好的双连续电极。双连续电极可以提高锂空气电池的动力学性能，减少堵塞引起的降解。为了增强拉曼信号，双连续电极将通过吸附均匀有序组装的金纳米粒子来修饰。修饰电极可以允许通过表面增强拉曼光谱检测沉积在电极上的痕量中间化合物。PI提出将改性电极与稳定溶剂（二甲氧基乙烷、二甲基亚砜和四（乙烯）乙二醇二甲醚等）一起制备锂-空气电池。一套表征工具（包括拉曼，FTIR， TEM， XPS和XRD）应该能够研究空气阴极上的材料。特别感兴趣的是在充放电过程中沉积在阴极上的中间化合物，这将通过SERS拉曼光谱来阐明，以解决与电解质/电极稳定性相关的基本材料挑战。该研究将为未来设计原位SERS拉曼表征技术提供基础，通过对电极上化学信息的持续研究，阐明阴极反应机理。最终，这可能会为高性能、可逆的锂空气电池提供新的工程解决方案。更广泛的影响：了解电极反应机理是提高电化学储能系统容量和可循环性的必要条件。这对于材料和工艺设计也是至关重要的。由于锂空气电池的理论电容很高，并且在消费者和工业应用中可能对这些电池有很高的需求，因此即使是在可循环性或效率方面的适度进步，其潜在影响也是相当大的。这既要考虑经济效益，也要考虑环境效益，因为增加电池容量将降低更换率，并可能允许新技术取代旧技术。这可能包括用电动马达取代内燃机，用于运输系统。与这项研究相关的概念将通过各种外展计划传播给更广泛的公众受众。当地的推广工作将包括面向4-6年级学生的科学奥林匹克周末竞赛，面向面向高中学生的UA-Harker项目，该项目旨在与高分子科学和高分子工程学院的教授合作。此外，PI的小组积极参与ACS SEED计划，以促进经济困难的当地高中生的研究活动。这些外展活动的目标是(1)说明动手纳米技术，(2)激发学生对科学和技术的兴趣，以便鼓励他们考虑在STEM领域从事职业，以及(3)教授与化学过程工程相关的挑战和机遇。

Zhu - 1505943This project is aimed at developing lithium-air batteries for use in electrically powered vehicles as alternatives to vehicles that run on fossil fuels. To compete with commercial internal combustion engines, electricity storage systems have to be significantly improved in energy density, power density and reversibility. Lithium-air batteries have the potential to significantly enhance the energy density but they are still immature and suffer from many issues, including the fact that they have sluggish and irreversible cathode reactions. Because the cathode reaction mechanism of the lithium-air battery is unclear, it is very difficult to design electrodes and electrolytes that cycle better. The primary objective in this research is to synthesize a bicontinuous, SERS (surface-enhanced Raman spectroscopy)-active electrode for lithium-air batteries and study the mechanism of charging/discharging processes by Raman spectroscopy. This is an EAGER grant to demonstrate the feasibility of the fabrication process.Intellectual Merit: This project seeks to fabricate the SERS-active electrodes to study the products formed on the cathode. The rationale for fabricating well organized bi-continuous 3D porous electrodes is to provide, simultaneously, a large effective surface area and an improvement in the electrolyte and oxygen diffusion. Lithium-air battery cathode reactions are complicated and sensitive to the local electrochemical environment. It is important to study the mechanisms of the battery electrode reactions to gain chemical information about the electrode throughout the charging/discharging process. In this work, the PI plans to use polymer templates to fabricate well-organized bicontinuous electrodes made of pristine chemical vapor deposited graphene. The bi-continuous electrodes can enhance the lithium-air battery kinetic performance and reduce the clog induced degradationTo enhance the Raman signals, the bi-continuous electrodes will be modified by the adsorption of uniform and regularly assembled gold nanoparticles. The modified electrodes may allow the detection, by surface-enhanced Raman spectroscopy, of trace intermediate compounds deposited on the electrodes. The PI proposes to use the modified electrode with stable solvents (Dimethoxyethane, Dimethyl sulfoxide and Tetra(ethylene) glycol dimethyl ether etc.) to fabricate lithium-air battery. A suite of characterization tools (including Raman, FTIR, TEM, XPS, and XRD) should enable the investigation of the materials on the air-cathode. Of particular interest are intermediate compounds deposited on the cathode during the charging and discharging processes that will be elucidated by SERS Raman spectroscopy to address fundamental material challenges associated with electrolyte/electrode stability. This research will provide the bases to design in-situ SERS Raman characterization techniques in the future, which may elucidate the cathode reaction mechanisms through the continuous investigation of the chemical information on the electrodes. Ultimately this may point to new engineering solutions for high performance, reversible lithium-air batteries.Broader Impacts: Understanding the electrode reaction mechanism is needed to improve capacity and cyclability of electrochemical energy storage system. This is also pivotal for material and process design. Due to the high theoretical capacitance of lithium-air battery and the possible high demand for these batteries in consumer and industrial applications, the potential impact from even a modest advance in cyclability or efficiency is quite large. There are both economic and environmental benefits to consider because increased battery capacity will decrease the replacement rate and may allow for the substitution of new technology for old. This could include the replacement of the internal combustion engine with electrical motors for uses in transportation systems. Dissemination of concepts associated with this research will be to a broader, public audience through various outreach programs. Local outreach efforts will include Science Olympiad weekend for students in grades 4-6, the UA-Harker program for high-school students working with professors in the institute of polymer science and polymer engineering. Additionally, the PI's group is active in ACS SEED program to promote the research activities of economically disadvantaged local high school students. The goal of these outreach activities are to (1) illustrate hands-on nanotechnology, (2) excite students about science and technology so that they may be encouraged to consider careers in STEM fields, and (3) teach about challenges and opportunities associated with the engineering of chemical processes.