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

非技术概述这个职业项目由材料研究部的固态和材料化学项目支持，旨在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本见解，以满足快速增长的电动汽车和储能市场的需求。储能是能够广泛采用可再生能源和加速实现二氧化碳负排放的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，以揭示反应机理，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，这些材料来自20世纪80年代发现的插层材料。在这些常规材料中，锂离子有明确的传输路径。最近，在锂离子传输途径无序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，这些材料的电池性能较差，尽管理论上它们应该提供更高的容量。这个项目使用先进的实验方法来发展对这些新的无序材料中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一个知识库。该项目还无缝地将研究与为美国培养未来劳动力结合在一起。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。阅读障碍学生在STEM领域是一个代表不足的群体，正如历史告诉我们的那样，他们可能是巨大的智力资产，例如在电池研究领域。除了这一努力，该职业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项目，允许本科生在国家实验室进行研究。总体而言，通过这个职业项目，林教授培养了几个未被充分代表的少数族裔学生，帮助他们在科学研究方面出类拔萃，并成为能源储存领域的未来领导者。技术概述这个职业项目由材料研究部固态和材料化学项目支持，研究一个新兴的先进电池材料家族的结构-性能关系。该项目各种研究目标背后的假设是，富锂无序岩盐氧化物具有全球无序的锂渗流网络和结合的阳离子/阴离子氧化还原活性，可能会提高电池的能量密度，远远超过传统的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不可逆的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，以了解化学、结构和氧化还原性质在多个长度和时间尺度上、在材料合成过程中和在电化学操作条件下的变化，以解决这些艰巨的挑战。该项目采用包括同步辐射X射线技术和电化学诊断在内的实验方法来完成以下目标：(1)探测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)研究氧化还原化学作为化学成分、局部配位环境、全局相特征和电化学的函数；(3)量化长期电化学循环下局部配位环境、全局平均相和氧化还原化学的多尺度演化。综上所述，这些研究的结果提供了对无序岩盐氧化物电化学的机械洞察和推进。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.