RII Track-4: Deciphering the Role of Polarization on Ion Transport in Ionic Liquid Batteries

锂离子电池的安全可靠运行主要取决于所使用的电解质类型。离子液体是一种完全由离子组成的新型溶剂，就像普通盐一样，但在电池工作温度下以液体的形式存在。由于低挥发性和不可燃性，离子液体作为电解质提供了令人兴奋的机会。有可能设计出100万种离子液体和大约10亿个离子液体-离子液体混合物，为开发下一代锂离子电池提供材料平台。尽管有这些显著的优势，但由于锂离子传输缓慢，增加了充电时间，离子液体基锂离子电池的进展受到限制。因此，当前项目的目标是了解离子液体-锂的相互作用，从而设计出用于快速锂离子传输的新型离子液体。通过与太平洋西北国家实验室（PNNL）的研究人员合作，PI将利用最先进的建模技术和美国能源部的领导计算设施，开发研究离子液体-锂相互作用的能力。所开发的专业知识将与俄克拉荷马州立大学的本科生和研究生以及该司法管辖区的研究人员共享。预计这项奖学金的合作将促进俄勒冈州立大学和太平洋西北国家实验室的研究人员的接触，并促进新思想的发展，加速多个科学和工程学科的发现。锂离子电池是一种很有前途的可持续交通技术解决方案。锂离子电池的主要组成部分之一是电解质，锂离子的有效传输对电池的可靠运行至关重要。室温离子液体很容易满足所需的电解质性能，如电化学稳定性、不挥发性、不可燃性和在宽温度范围内的高导电性。尽管具有显著的优势，但离子液体作为电解质的应用受到阻碍，因为许多离子液体的高粘度阻碍了锂离子的传输，导致充放电时间缓慢。混合两种离子液体提供了一种简单而有力的策略来克服这一挑战。然而，目前缺乏对哪种离子液体组合可能产生有前途的电解质的基本理解。此外，这种混合物的精确建模需要捕获离子周围电子分布的成分依赖变化，突出了极化的必要性。基于密度泛函理论的第一性原理分子动力学（FPMD）方法自然地将这一关键方面纳入了离子液体建模中。PI将在他的研究小组中与太平洋西北国家实验室的研究人员合作开发这种能力。FPMD模拟将在美国能源部的领先计算设备上进行，用于离子液体混合物、Li+-离子液体混合物、电极界面和电场存在下的离子液体。新开发的专业知识将与东道国的研究人员分享，从而提高其研究能力。该奖学金将培训一名研究生，并将FPMD模拟整合到PI的“分子建模与模拟”课程中。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。

Safe and reliable operation of Li-ion batteries depends critically on the type of electrolytes used. Ionic liquids, novel solvents composed entirely of ions much like common salt but existing as liquids at the temperatures of battery operation, present exciting opportunities as electrolytes due to low volatility and nonflammability. Potentially a million ionic liquids and roughly a billion ionic liquid-ionic liquid mixtures can be designed providing a materials platform for developing next generation of Li-ion batteries. Despite these significant advantages, the progress in ionic liquid-based Li-ion batteries has been limited due to slow Li-ion transport, which increases the time for charging. The objective of the current project is, therefore, to understand ionic liquid-Li interactions to enable the design of novel ionic liquids for fast Li-ion transport. By partnering with researchers from the Pacific Northwest National Laboratory (PNNL), the PI will develop the capability to study ionic liquid-Li interactions using state-of-the-art modeling techniques and DOE's Leadership Computing Facilities. The expertise developed will be shared with undergraduate and graduate students at Oklahoma State University and researchers in the jurisdiction. It is expected that the collaboration resulting from this fellowship will foster engagement of researchers at OSU with those at PNNL and lead to development of new ideas accelerating discoveries in multiple science and engineering disciplines.Li-ion batteries present a promising technological solution for sustainable transportation. One of the major components of Li-ion batteries is the electrolyte through which an efficient transport of Li ions is critical for reliable operation. Room temperature ionic liquids easily fulfill the required electrolyte properties such as electrochemical stability, nonvolatility, nonflammability, and high conductivity over a wide range of temperatures. Despite significant advantages, application of ionic liquids as electrolytes is hampered because the high viscosity of many ionic liquids hinders transport of Li ions causing slow charging and discharging times. Mixing two ionic liquids offers a simple yet powerful strategy to overcome this challenge. However, currently there is a lack of fundamental understanding regarding which ionic liquid combinations are likely to yield promising electrolytes. Further, accurate modeling of such mixtures necessitates capturing the composition-dependent changes in electronic distributions around ions, highlighting the need for polarization. First principles molecular dynamics (FPMD) based on density functional theory approach naturally incorporates this crucial aspect in modeling ionic liquids. The PI will develop this capability in his research group by partnering with researchers from the Pacific Northwest National Laboratory. FPMD simulations will be performed on DOE's Leadership Computing Facilities for ionic liquid mixtures, Li+-ionic liquid mixtures, ionic liquids at electrode interfaces and in the presence of electric field. The newly developed expertise will be shared with researchers at the host institution increasing its research capacity. The proposed fellowship will lead to the training of a graduate student and integration of FPMD simulations in the PI's 'Molecular Modeling and Simulation' course.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.