CAREER: Multifunctional electrolyte design and descriptors for lithium metal batteries

迫切需要加快全球脱碳努力，以支持可持续的能源经济。由于太阳能和风能等可再生能源技术的间歇性，需要储能。电池非常有希望，因为它们可以携带和能量密集型(单位质量存储的能量)。锂金属电极电池可以储存的能量是目前可用的锂离子电池的两倍，但由于缺乏合适的电解液(溶于溶剂的盐)，还没有商业化。这一基础研究项目将确定对预测金属锂电极行为非常重要的相关电解液性质，并利用这些见解开发允许锂金属电池使用更长时间的新型电解液。该教育计划将重点利用与电池有关的编程活动(例如戏剧表演和电池实验)，作为一年一度的“电池日”活动的一部分，以扩大芝加哥和尼日利亚当地和国际上未被充分代表的少数族裔在STEM中的参与和坚持。该项目的综合研究和教育计划将导致高能量密度的金属锂电池，使美国更接近实现脱碳目标，扩大学习STEM的人数不足的少数族裔学生的数量，并使美国劳动力多样化，具有全球竞争力。锂金属电池具有理论能量密度，但锂金属电池沉积在高表面积苔藓和/或树枝状形态，高度依赖于电解液成分。在连续循环中，不均匀的锂沉积和剥离会导致固体电解质界面(SEI)组分的积累，以及电化学不活跃(或“死”)的锂，从而导致永久性的产能损失。一种很有希望解决锂金属挑战的方法是电解液设计。然而，电解液的要求是复杂的，因为它们必须是不挥发和不可燃的，并且具有高离子导电性、高锂迁移数和高电化学稳定性。因此，物理混合物经常被用在爱迪生方法中，这使得电解质的发展具有高度的组合性。为了解决这些电解液设计挑战，本项目将有以下目标：(1)量化电解液的溶剂化性质并开发相关的电解液描述符(2)设计一个模块化的多功能电解液平台，该平台将不同的电解液性质共价结合到单个分子中，(3)评估多功能电解液对锂金属电池的影响，并探测锂金属在原位和异地的动态变化。这项研究将为定量电解液科学和用于广泛电化学系统的新型电解液开辟一条新的道路。这一奖项反映了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。

There is a pressing need to accelerate worldwide decarbonization efforts to support a sustainable energy economy. Due to the intermittency of renewable energy technologies such as solar and wind, energy storage is required. Batteries are highly promising because they can be portable and energy-dense (energy stored per mass). Lithium metal electrode batteries can store up to two times the energy of currently available Li-ion batteries but have not been commercialized because of the lack of suitable electrolytes (salts dissolved in solvent). This fundamental research project will determine relevant electrolyte properties that are important to predict lithium metal electrode behavior and use those insights to develop novel electrolytes that allow for lithium metal batteries that last longer. The educational plan will focus on using battery-related programming events (e.g. drama performance and battery experiments) as part of an annual “Battery Day” event to broaden the participation and persistence of underrepresented minorities in STEM both locally in Chicago and internationally in Nigeria. The project’s integrated research and educational plan will lead to energy-dense lithium metal batteries that bring the US closer to achieving decarbonization goals, expand the number of underrepresented minority students pursuing STEM, and enable a diverse and globally competitive US workforce.Lithium metal batteries have theoretical energy densities, but lithium metal deposits in a high surface area mossy and/or dendritic morphology that is highly dependent on electrolyte composition. With continuous cycling, uneven lithium deposition and stripping leads to the accumulation of solid electrolyte interphase (SEI) components and electrochemically inactive (or ‘dead’) lithium leading to permanent capacity loss. One approach with great promise to address lithium metal challenges is electrolyte design. However, electrolyte requirements are complex as they must be nonvolatile and nonflammable and have high ionic conductivity, high lithium transference number, and high electrochemical stability. Hence, physical mixtures are often used in an edisonian approach that makes electrolyte development highly combinatorial. To solve these electrolyte design challenges, this project will have the following objectives: to (1) quantify electrolyte solvation properties and develop relevant electrolyte descriptors (2) design a modular multifunctional electrolyte platform that covalently combines disparate electrolyte properties into a single molecule and (3) evaluate multifunctional electrolyte influence in lithium metal batteries and probe dynamic lithium metal changes in situ and ex situ. The research will chart a new path forward for quantitative electrolyte science and novel electrolytes for a broad range of electrochemical systems.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.