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

PI姓名：Subramanian，Arunboutiar提案ID：1453966电动汽车是减少化石燃料消耗和温室气体产生的一种替代方案，以满足可持续运输需求。 电动汽车需要平衡电能存储和电力输送需求的可充电电池，并且这些电池必须具有足以降低成本并实现真正的碳足迹减少的寿命。 此外，电池应采用可持续材料制造，以尽量减少对环境的影响。 为了实现这些目标，这项研究旨在通过改善由基于锂锰氧化物混合物的可持续材料制成的电极的寿命来促进锂离子（Li离子）电池技术的可持续性。 该研究计划的一个独特方面是研究由单个“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，这项研究将推动储能技术的发展，以满足未来清洁能源的需求，特别是在交通运输领域。与该奖项相关的教育和推广计划将把研究成果的影响扩展到弗吉尼亚州里士满更广泛的STEM教育生态系统。 教育活动包括K-12外展计划通过？纳米研究员研究所和夏季地区州长学校在数学科学创新中心（MSIC）的倡议，并通过里士满地区少数民族工程计划（RAPME）。这些计划将向学生介绍令人兴奋的机会，这些机会可以作为未来的科学家和工程师在可持续能源领域产生社会影响。该CAREER奖项的总体技术目标是通过对由可持续锂/锰氧化物复合材料制成的单插层纳米线阴极的重点分析，对锂离子电池的固有存储容量有基本的了解。为此，第一个研究目标是测量单个α相二氧化锰（MnO 2）纳米线阴极的锂存储容量，其分辨率优于0.03个Li原子/主体分子。 单一的二氧化锰纳米线将进行不同的电化学循环深度，以揭示晶体变化和容量保持率之间的相关性。 第二个目标测试的假设，即在这些嵌入阴极的固有容量衰减将得到改善，通过最大限度地减少结构和电子电导率的变化，这发生在其主机晶体在可逆的离子嵌入。 这将通过使用受控的锂掺杂和进一步的氨处理来实现，以通过减轻Jahn-Teller畸变来稳定主晶体的2x2隧道结构。 在实验上，锂/二氧化锰纳米线电池将与纳米机电谐振器集成，以通过其电化学诱导的质量变化来量化纳米线的锂容量。 将在该单根纳米线上以分布在其循环寿命内的特定充放电循环次数进行四次电化学相关测量：（1）TEM成像以表征微观结构，（2）电子电导率测量，（3）接触模式AFM以研究纳米机械软化，以及（4）使用基于原位电子显微镜的动态共振测量的充电容量测量。由于容量衰减与渐进循环是一个关键的故障模式，这是常见的不同的电极材料系统以及不同的离子嵌入系统，新的科学知识和其他先进的实验能力，这将出现从这一努力，有可能超越锂-二氧化锰系统，并改变电极设计策略，为未来的电化学储能系统。

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.