Dynamics of solvation effects on lithium-sulfur electrochemical processes in sub-nano confinement

1604908 PI：Guo标题：亚纳米限制锂硫电化学过程中溶剂化效应的动力学与商用锂离子电池相比，锂硫电池(Li-S)具有以更低的成本提供更高能量密度的潜力。与仅涉及固态锂离子电池的锂-脱硫化反应不同，锂离子电池涉及在能够溶解多硫化锂化合物的液体电解液中进行反应，以克服硫的高度绝缘性造成的障碍。目前，锂-S电池的性能受到锂-S电化学反应和脂多糖扩散时间尺度的差异的限制。拟议项目的总体目标是研究新的电极设计，使硫能够限制在亚纳米结构中，并消除脂多糖溶解引起的问题。该项目的关键科学目标是了解限制对微孔碳和单壁碳纳米管中硫的电化学行为的影响，以提高锂S电池的性能。在锂-S电池中，锂-脱硫化过程需要一系列固-液-固反应。为了提高硫的利用率，液体电解液必须溶解中间的脂多糖化合物，但在每一次循环中，一些脂多糖会通过扩散离开电极而损失。亚纳米限制可以通过阻止溶剂进入硫电极上的孔来克服这一挑战，因此Li+离子只能通过去溶进入孔内，有效地将Li-S反应固定在电极表面。这项拟议的研究将通过协调一致的实验和建模工作来研究亚纳米限制下Li-S电化学的基本机制。除了培训研究生，PIS计划让本科生参与研究，并提出一项外联努力，重点是吸引Rialto联合学区高中代表不足的少数族裔学生。这一研究项目的成果可能会对多孔纳米结构中的亚纳米限制领域产生更广泛的影响。

1604908 PI: GuoTitle: Dynamics of solvation effects on lithium-sulfur electrochemical processes in sub-nano confinementLithium-sulfur (Li-S) batteries have the potential of providing higher energy density at a lower cost, when compared to the commercially available lithium-ion batteries. In contrast to Li-ion batteries that involve only solid state lithiation-delithiation reactions, Li-S batteries involve reactions in liquid electrolytes capable of dissolving lithium polysulfide (LPS) compounds in order to overcome the barriers posed by the highly insulating nature of sulfur. The performance of Li-S batteries is currently limited by the difference in the time scales of Li-S electrochemical reactions and LPS diffusion. The overarching goal of the proposed project is to investigate new electrode designs that enable the confinement of sulfur in sub-nanometer structures and eliminate the problems arising from LPS dissolution. The key scientific objective of the proposed project is to understand the effects of confinement on the electrochemical behavior of sulfur in microporous carbon and single-walled carbon nanonutubes in order to improve the performance of Li-S batteries. In Li-S batteries, the lithiation-delithiation process requires a sequence of solid-liquid-solid reactions. The liquid electrolyte must dissolve the intermediate LPS compounds for high sulfur utilization, but some LPS is lost in each cycle through diffusion away from the electrode. Sub-nano confinement could overcome this challenge by blocking the solvent from entering the pores on the sulfur electrode, so Li+ ions can only enter the pores through desolvation, effectively immobilizing the Li-S reaction on the electrode surface. The proposed research will examine the fundamental mechanisms of Li-S electrochemistry with sub-nano confinement through a concerted experimental and modeling effort. In addition to training graduate students, the PIs plan to involve undergraduate students in research and propose an outreach effort focused at engaging underrepresented minority students from the Rialto Unified School District High Schools. The outcome of this research project may have a broader impact on the field of sub-nano confinement in porous nanostructures.