CAREER: Sustainable Solutions for Li-ion Batteries through Cycle-Life Improvements in Nanostructured, 'Green' Cathodes

PI姓名：Subramanian， ArunkumarProposal ID: 1453966电动汽车是减少化石燃料消耗和温室气体排放以满足可持续交通需求的一种替代方案。电动汽车需要可充电电池来平衡电能储存和电力输送需求，这些电池必须有足够的寿命来降低成本并实现真正的碳足迹减少。此外，电池应该由可持续材料制造，以尽量减少对环境的影响。为了实现这些目标，本研究旨在通过基于锂-锰氧化物混合物的可持续材料制成的电极的寿命改进来推进锂离子（Li-ion）电池技术的可持续性。该研究计划的一个独特之处在于研究由单个“纳米线”制成的电池材料，以更好地了解减少锂离子电池寿命的基本过程。如果成功，这项研究将推进能源存储技术，以满足未来的清洁能源需求，特别是在运输部门。与该奖项相关的教育和推广项目将把研究成果的影响扩展到弗吉尼亚州里士满地区更广泛的STEM教育生态系统。教育活动包括通过？在数学科学创新中心（MSiC）的纳米研究员研究所和夏季地区州长学校倡议，并通过里士满地区工程少数民族计划（RAPME）。这些举措将为学生们带来令人兴奋的机会，让他们成为可持续能源领域未来的科学家和工程师，对社会产生影响。CAREER奖的总体技术目标是通过对可持续锂/锰氧化物复合材料制成的单嵌层纳米线阴极的重点分析，获得对锂离子电池内在存储容量的基本理解。为此，第一个研究目标是测量单个α相二氧化锰（MnO2）纳米线阴极的锂存储容量，其分辨率优于每个主分子0.03个锂原子。为了揭示单根二氧化锰纳米线晶体变化与容量保持之间的关系，我们将对其进行不同的电化学循环深度。第二个目标测试了这样一个假设，即在可逆离子插入过程中，通过最小化结构和电子导电性的变化，可以改善这些插入阴极的固有容量衰减。这将通过使用可控的锂掺杂和进一步的氨处理来实现，通过减轻Jahn-Teller扭曲来稳定宿主晶体的2x2隧道结构。实验中，锂/二氧化锰纳米线电池将与纳米机电谐振器集成，通过电化学诱导的质量变化来量化纳米线的锂容量。四项电化学相关测量将在单纳米线上进行，具体的充放电循环次数分布在其循环寿命中：(1)TEM成像表征微观结构，(2)电子电导率测量，(3)接触模式AFM研究纳米力学软化，(4)使用基于原位电子显微镜的动态共振测量进行电荷容量测量。由于容量随渐进循环而衰减是不同电极材料系统以及不同离子插层系统共同存在的关键失效模式，因此从这项工作中产生的新科学知识和其他先进实验能力，有可能超越锂- mno2系统，并改变未来电化学储能系统的电极设计策略。

PI Name: Subramanian, ArunkumarProposal ID: 1453966Electric vehicles are one alternative for reducing fossil fuel consumption and greenhouse gas production for sustainable transportation needs. Electric vehicles require rechargeable batteries that balance the electrical energy storage and power delivery needs, and these batteries must have a life span sufficient to reduce cost and achieve true carbon footprint reduction. Furthermore, batteries should be manufactured from sustainable materials to minimize environmental impact. Towards these ends, this research seeks to advance the sustainability of lithium-ion (Li-ion) battery technology through life-span improvements of electrodes made from sustainable materials based on lithium-manganese oxide mixtures. A unique aspect of the research plan is to study battery materials made from single "nanowires" to better understand the fundamental processes that reduce lithium-ion battery lifespan. If successful, this research will advance energy storage technology for future clean energy needs, particularly in the transportation sector. The education and outreach programs associated with this award will extend the impact of the research outcomes into the broader, STEM educational ecosystem in the Richmond, Virginia region. Educational activities include K-12 outreach programs delivered through the ?NanoFellows Institute and Summer Regional Governor's School initiatives at the Math Science Innovation Center (MSiC), and through the Richmond Area Program for Minorities in Engineering (RAPME). These initiatives will introduce students to exciting opportunities that exist for delivering societal impact as future scientists and engineers to the area of sustainable energy.The overall technical goal of this CAREER award is to gain a fundamental understanding of intrinsic storage capacity in Li-ion batteries through a focused analysis on single intercalation nanowire cathodes made from sustainable lithium/manganese oxide composites. Towards this end, the first research objective is to measure the lithium storage capacity of a single alpha-phase manganese dioxide (MnO2) nanowire cathode with a resolution better than 0.03 Li atoms per host molecule. Single MnO2 nanowires will be subjected to different electrochemical cycling depths in order to reveal the correlation between crystal changes and capacity retention. The second objective test the hypothesis that the intrinsic capacity fading in these intercalation cathodes will be improved by minimizing the structural and electronic conductivity changes, which occur within their host crystal during reversible ionic intercalation. This will be achieved by the use of controlled lithia-doping and further ammonia treatment to stabilize the 2x2 tunnel structure of the host crystal through alleviation of Jahn-Teller distortions. Experimentally, lithium/manganese dioxide nanowire cells will be integrated with nanoelectromechanical resonators to quantify the lithium capacity of the nanowire through its electrochemically-induced mass changes. Four electrochemically-correlated measurements will be performed on this single nanowire at specific charge-discharge cycle numbers that are spread over its cycle-life: (1) TEM imaging to characterize the microstructure, (2) electronic conductivity measurements, (3) contact-mode AFM to study nanomechanical softening, and (4) charge capacity measurement using in-situ electron microscopy-based dynamic resonance measurements. Since capacity fading with progressive cycling is a key failure mode that is common to diverse electrode material systems as well as to different ionic intercalation systems, the new scientific knowledge and other advanced experimental capabilities, which will emerge from this effort, have the potential to go beyond the lithium-MnO2 system and to transform the electrode design strategies for future electrochemical energy storage systems.