In-situ morphology characterization of self-assembled high-energy density mesoporous electrodes using x-ray and neutron scattering

纳米多孔材料在电化学储能方面具有广泛的应用前景。对于插入式电池电极，这些孔隙通过适应大的体积变化，在充放电循环中提供了更好的形态稳定性。然而，形态学结构与性能之间的关系仍然普遍缺乏；特别是，复杂的多组分和多尺度材料应该能够显著提高性能。例如，与石墨或纯金属氧化物相比，金属氧化物或硅的碳涂层提供了更好的性能。该项目旨在为设计和表征锂插入电池电极的混合材料提供一个基本框架，使用定义良好的模型材料，并结合原位多尺度（原子和介观）表征和测试程序。自组装有序材料提供了模型电极，使人们能够从根本上了解循环过程中的形态演变和扭曲如何影响电池的长期容量。在这项工作中，我们建议使用酚醛树脂（碳前驱体）和(1)溶胶-凝胶掺锂的五氧化二钒或(2)硅纳米颗粒的协同自组装来制造有序的介孔纳米复合材料作为模型材料，通过该模型材料可以阐明结构-性能关系。这种自组装路线可以实现接近单分散的孔径、壁厚和传输路径，从而从根本上研究孔径和纳米颗粒（Li-V2O5或Si）含量对这些纳米复合材料作为插入电池电极性能的影响。纳米复合基质允许大量的Li（通过插入Li- v2o5或Si）和高电极导电性（通过连续的碳路径）。PI建议系统地改变纳米颗粒：碳比和纳米颗粒尺寸/溶胶老化，以提高对形态-性质关系的理解，并通过其明确的中尺度结构得到加强。一套表征工具（包括TEM，孔隙率测定和散射）将使结构与标准电化学性能测试相关联。特别感兴趣的是充放电条件下的结构变化，包括膨胀、消肿和变形，这些变化将通过原位掠入射小角x射线散射和旋转小角中子散射来阐明，以解决与电极稳定性相关的基本材料挑战。在电化学测试中提出了新的原位小角散射研究，以阐明固体-电解质间相的形成以及通过纳米结构和改进的充放电循环控制来减轻性能损失的潜在途径。综合这些研究将提高对多孔锂离子电池阳极结构-性能关系的基本理解，并有可能为高性能电池提供新的工程解决方案。电池技术的进步源于对电池基本原理的理解，可以提高电池效率，提高电池在高功率应用中的使用，延长电池寿命。由于锂插入电池在消费和工业应用中的使用率越来越高，即使是在效率和寿命方面的适度进步也会产生相当大的潜在影响。由于电池寿命的延长将降低应用中电池的更换率，特别是考虑到从消费电子产品到交通运输的电池市场不断增长，因此需要考虑经济和环境效益。通过与UA-St的伙伴关系，将向更广泛的公众传播与这项研究有关的概念。文森特?美国高中（STVM）和为全国K-12教师提供材料的阿克伦全球聚合物学院（AGPA）；额外的地方推广工作将包括通过AGPA的联系，前往6-10年级的教室。

Nanoporous materials are attractive for electrochemical energy storage applications. For insertion battery electrodes, these pores provide improved morphological stability during charge-discharge cycles through accommodation of large volumetric changes. However, relationships between morphological structure and performance are still, in general, lacking; in particular, complex multi-component and multi-scale materials should enable significant improvements in performance. For example, carbon coating of metal oxides or silicon provides improved performance in comparison to graphite or pure metal oxide. This project seeks to provide a fundamental framework for the design and characterization of hybrid materials for Li insertion battery electrodes using well-defined model materials in conjunction with an in-situ multiscale (atomic and meso) characterization and testing program.Self-assembled ordered materials provide model electrodes to enable fundamental insight into how morphology evolution and distortion during cycling impacts long term battery capacity. In this work, we propose to use cooperative self assembly of phenolic resin (carbon precursor) and (1) sol-gel Li-doped vanadium pentoxide or (2) silicon nanoparticles to fabricate ordered mesoporous nanocomposites as model materials by which structure-property relationships can be elucidated. This self-assembly route enables near monodisperse pore sizes, wall thickness and transport paths for fundamentally examining the impact of pore size and nanoparticle (Li-V2O5 or Si) content on the performance of these nanocomposite materials as insertion battery electrodes. The nanocomposite matrix allows for significant incorporation of Li (through insertion in Li-V2O5 or Si) and high electrode conductivity (through continuous carbon pathways). The PI proposes to systematically vary the nanoparticle:carbon ratio and the nanoparticle size/sol aging to develop an improved understanding of morphology-property relationships, enhanced by their well-defined mesoscale structure. A suite of characterization tools (including TEM, porosimetry, and scattering) will enable correlation of structure to standard electrochemical performance tests. Of particular interest are structural changes involving swelling, de-swelling, and distortion under charge-discharge conditions that will be elucidated by in-situ grazing incidence small angle x-ray scattering and rotational small angle neutron scattering to address fundamental material challenges associated with electrode stability. Novel in-situ small angle scattering studies during electrochemical testing are proposed to elucidate solid-electrolyte interphase formation and potential routes to mitigate performance loss through nanostructuring and improved control of charge-discharge cycles. Combined these studies will provide improved basic understanding of structure-property relations for porous Li ion battery anodes and potentially provide new engineering solutions for high performance batteries.Advances in battery technology from improved fundamental understanding developed could lead to improved battery efficiency, battery usage in higher power applications and increased battery lifetime. Due to the growing utilization of Li insertion batteries in consumer and industrial applications, the potential impact from even modest advances in efficiency and lifetime is quite large. There are both economic and environmental benefits to consider as increased battery lifetime will decrease the replacement rate for batteries in applications, especially considering the growing market for batteries from consumer electronics to transportation. Dissemination of concepts associated with this research will be disseminated to a broader, public audience through partnership with UA-St. Vincent?s High School (STVM) and the Akron Global Polymer Academy (AGPA) that provides materials to K-12 teachers nationwide; additional local outreach effort will include trips to classrooms for grades 6-10, through AGPA connections.