Understanding interphase layer formation at the cathode/solid-electrolyte junction

为了支持从消费电子到电动汽车的广泛技术，提高锂离子电池的安全性和性能是必要的。目前的锂离子电池使用有机液体电解液，允许锂离子在充电和放电期间在电池电极之间快速移动。但这些液体电解液是易燃的，允许锂金属卷须(称为树枝状)在电极之间生长，导致短路和电池反应失控的风险。在过去的30年里，研究人员一直在努力开发固体电解液材料来取代锂离子电池中的液体电解液，以提高安全性、寿命和能量密度。然而，这些电解液材料在电池测试单元中很快就会失效。密苏里大学的研究人员将致力于了解这些电解液因固体电解液和电池阴极之间的反应而产生故障的原因。为了实现这一点，密苏里大学的研究人员将结合物种选择膜涂层、电子显微镜和电化学表征来分离和了解不同活性物种对整体失效行为的单独贡献。这项研究将填补在理解导致固体电解质失效的反应方面的一个关键空白，并有望帮助研究人员开发更安全、更高性能的电池。这些研究活动将与开发动手互动学习模块相辅相成，使早期高中生对电池界面的电子显微镜测量变得有形和有趣。该项目将建立对氧化物正极材料和硫化物固体电解液之间界面形成机制的理解。研究人员将使用先进的透射电子显微镜和其他互补的表征技术来观察镍钴锰(NMC)阴极粉末和Li10GeP2S12(LGPS)SE之间的界面形成，以及使用分子层沉积(MLD)在NMC阴极上形成和不在NMC阴极上形成纳米级聚合物膜的情况。这些MLD膜涂层可作为电子、阳离子和阴离子的单一或混合导体进行调节，有助于分离和了解这些物种中的每一种对相间形成反应的贡献。该项目将(1)了解天然阴极/固体电解质界面形成与阴极荷电状态的关系，(2)了解电子、阳离子和阴离子在阴极/电解质界面形成中的作用，以及(3)了解屏障涂层对固态电池性能的影响。这项工作将帮助研究人员合理地提出解决方案，以阻止不必要的反应，同时保持阴极/固体电解质界面的理想功能特性。该奖项反映了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。

Improving the safety and performance of lithium-ion batteries is necessary to support a broad range of technologies from consumer electronics to electric vehicles. Current lithium-ion batteries employ organic liquid electrolytes that allow lithium ions to move rapidly between battery electrodes during charge and discharge. But these liquid electrolytes are flammable and allow for the growth of lithium metal tendrils (referred to as dendrites) between the electrodes, leading to the risk of short-circuiting and runaway cell reaction. Over the last 30 years, researchers have been working to develop solid electrolyte materials to replace liquid electrolytes in lithium-ion batteries for improved safety, lifetime, and energy density. However, these electrolyte materials fail rapidly in battery test cells. Researchers at the University of Missouri will work to understand the origins of failure in these electrolytes arising from reactions between the solid electrolyte and the cathode of the battery. To accomplish this, University of Missouri researchers will isolate and understand the individual contributions of different reactive species on the overall failure behavior using a combination of species-selective membrane coatings, electron microscopy, and electrochemical characterization. This research will fill a critical gap in understanding of the reactions that underpin failure of solid electrolytes and is expected to help researchers develop safer and higher performance batteries. These research activities will be complemented with the development of hands-on interactive learning modules to make electron microscopy measurements of battery interfaces tangible and engaging for early high-school students.This project will establish mechanistic understanding of interphase formation between oxide cathode materials and sulfide solid electrolytes. Researchers will employ advanced transmission electron microscopy and other complementary characterization techniques to observe interphase formation between nickel-cobalt-manganese (NMC) cathode powder and Li10GeP2S12 (LGPS) SE with and without nanoscale polymer membrane coatings formed on the NMC cathode using molecular layer deposition (MLD). These MLD membrane coatings are tunable as single or mixed conductors of electrons, cations, and anions and will help serve to isolate and understand each of these species’ contributions to interphase formation reactions. The project will (1) understand native cathode/solid electrolyte interphase formation versus the state of charge of the cathode, (2) understand the role of electrons, cations, and anions in cathode/electrolyte interphase formation, and (3) understand the impact of barrier coatings on solid state battery performance. This work will help researchers rationally propose solutions to block unwanted reactions while preserving desirable functional properties at the cathode/solid electrolyte interface.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.