CAREER: Understanding Chemical, Structural and Redox Properties of Disordered Metal Oxides

该职业项目由材料研究部固态和材料化学项目支持，为最终设计更高能量、更高功率和更稳定的可充电电池提供基础见解，以满足快速增长的电动汽车和能源存储市场的需求。储能技术是实现可再生能源广泛应用和加速二氧化碳负排放技术进步的关键技术。锂离子电池技术是最重要的储能技术之一。锂离子电池的进一步发展需要更多的基础研究，以揭示反应机制并为新材料的设计提供信息。尽管经过多年的材料开发，大多数商用锂离子电池仍然依赖于几种正极材料，这些正极材料来自于20世纪80年代发现的插层材料。在这些传统材料中，锂离子的运输有明确的途径。最近，在无序锂离子传输途径的新电池材料方面有了令人兴奋的发现。不幸的是，与传统材料相比，这些材料表现出较差的电池性能，尽管理论上它们应该提供更高的容量。本项目采用先进的实验方法来发展对这些新型无序材料的电化学过程的基本理解。该项目的成功成果将为进一步改进这些材料建立知识库。该项目还将研究与美国未来劳动力的教育无缝结合。它为弗吉尼亚州西南部有阅读障碍的小学生提供了学习机会。诵读困难的学生，在STEM领域是一个代表性不足的群体，可以成为巨大的智力资产，就像历史告诉我们的那样，例如在电池研究领域。除此之外，CAREER项目还在弗吉尼亚理工大学和国家实验室之间建立了一个可持续的教育计划，允许本科生在国家实验室进行研究。总的来说，通过这个CAREER项目，林教授教育了几个被忽视的少数民族学生，帮助他们在科学研究中脱颖而出，成为未来储能领域的领导者。该职业项目由材料研究部固态和材料化学项目支持，研究一系列新兴的先进电池材料的结构-性能关系。该项目各种研究目标背后的假设是，富含锂的无序岩盐氧化物具有全局无序的锂渗透网络和阳离子/阴离子氧化还原活性，可以潜在地提高电池的能量密度，远远超过传统层状阴极所提供的能量密度。然而，到目前为止，它们在电化学循环过程中的不可逆化学和结构转变阻碍了它们的实际应用。林教授和他的研究小组开展了全面的基础研究，以了解在材料合成和电化学操作条件下，化学，结构和氧化还原性质如何在多个长度和时间尺度上发生变化，以解决这些艰巨的挑战。该项目采用实验方法，包括同步加速器x射线技术和电化学诊断，以实现以下目标：(1)探索和控制机械合成过程中局部配位环境和全局平均相的演变；(2)研究化学成分、局部配位环境、全局相特征和电化学的氧化还原化学作用；(3)量化长时间电化学循环过程中局部配位环境、全局平均相和氧化还原化学的多尺度演变。综上所述，这些研究的结果为无序岩盐氧化物的电化学研究提供了机理上的见解。该奖项反映了美国国家科学基金会的法定使命，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。

Non-Technical SummaryThis CAREER project, supported by the Solid State and Materials Chemistry Program in the Division of Materials Research, advances fundamental insights into eventually designing higher energy, higher power, and more stable rechargeable batteries to meet the demand of the rapid-growing electric vehicle and energy storage market. Energy storage is a vital technology to enable the widespread adoption of renewable energy and to accelerate the technological advancement towards negative CO2 emission. The Li ion battery technology represents one of the most important energy storage technologies. Further development of Li ion batteries calls for more fundamental studies that can reveal reaction mechanisms and inform the design of new materials. Despite many years of materials development, most commercial Li-ion batteries still rely on several cathode materials that are derived from intercalation materials discovered in the 1980s. In these conventional materials, there are defined pathways for Li ions to transport. Recently, there have been exciting discoveries in new battery materials with disordered Li ion transport pathways. Unfortunately, these materials exhibit inferior battery performance compared to conventional materials, although theoretically they should provide much higher capacity. This project uses advanced experimental methods to develop fundamental understanding of electrochemical processes in these new disordered materials. The successful outcome of this project will establish a knowledge base for further improving these materials. This project also seamlessly integrates research with educating the future workforce for the United States. It provides learning opportunities for elementary students with dyslexia in Southwest Virginia. Dyslexic students, an underrepresented group in STEM fields, can be enormous intellectual assets as history, for example in the field of battery research, has taught us. Separately from this effort, the CAREER project also establishes a sustainable educational program between Virginia Tech and national labs, allowing undergraduate students to perform research in national labs. Overall, through this CAREER project Prof. Lin educates several underrepresented minority students, helping them to excel at performing scientific research and to become future leaders in the energy storage field.Technical SummaryThis CAREER project, supported by the Solid State and Materials Chemistry Program in the Division of Materials Research, investigates the structure-property relationship for an emerging family of advanced battery materials. The hypothesis underlying the various research objectives of this project is that Li-rich disordered rocksalt oxides, with a globally disordered Li percolating network and combined cationic/anionic redox activities, can potentially increase battery energy density far beyond what is delivered by conventional layered cathodes. However, so far their irreversible chemical and structural transformations during electrochemical cycling have impeded their practical applications. Prof. Lin and his research group carry out holistic fundamental studies to understand how the chemical, structural, and redox properties transform at multiple length and time scales, during materials synthesis and under electrochemical operating conditions in order to resolve these daunting challenges. The project employs experimental methods, including synchrotron X-ray techniques and electrochemical diagnostics, to accomplish the following objectives: (1) probing and controlling the evolution of local coordination environment and global average phase during mechanosynthesis, (2) investigating the redox chemistry as a function of chemical composition, local coordination environment, global phase characteristics, and electrochemistry, and (3) quantifying the multiscale evolution of local coordination environment, global average phase, and redox chemistry upon prolonged electrochemical cycling. Taken together, results from these studies provide mechanistic insights into and advance the electrochemistry of disordered rocksalt oxide.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.