Hessling Janis, Dick Leonard, Keil Sophia, Alizadeh Vahideh, Hansen Michael Ryan, Kirchner Barbara, Schönhoff Monika
Institute of Physical Chemistry, University of Münster, Corrensstraße 28/30, Münster D-48149, Germany.
Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstraße 4-6, Bonn D-53115, Germany.
J Phys Chem B. 2025 Jun 26;129(25):6372-6384. doi: 10.1021/acs.jpcb.5c01702. Epub 2025 Jun 16.
Hybrid solid-state electrolytes, which combine ionic liquids with metal-organic frameworks, offer a promising approach to enhancing the safety and energy density of next-generation batteries. A thorough understanding of the interplay between the solid and liquid phases in hybrid solid-state electrolytes is crucial for optimizing their performance as battery electrolytes. This study investigates how interactions between different ionic liquid-based electrolytes and the metal-organic framework ZIF-8 influence the coordination and dynamics of Li in confinement. To this end, we examine five different ionic liquids, varying the chemical nature of the cation. Raman spectroscopy, supported by 2D solid-state NMR and simulations, are used to elucidate Li coordination and ion-wall interactions. The impact of these interactions on local Li dynamics and charge transport in the ionic liquid-ZIF-8 hybrid system is investigated using Li spin relaxation, impedance spectroscopy, and simulations. The results reveal a competitive interaction between Li and the ionic liquid cation with the ZIF-8 framework, which can be fine-tuned by modifying the molecular structure of the ionic liquid cation. As a consequence, local Li dynamics is enhanced, depending on the ionic liquid cation. The beneficial interactions in the confined system can even make Li the fastest diffusing species, in contrast to bulk electrolyte, where Li transport is limited by strong Li-anion clusters. Thus, blocking Li-framework interactions through other competitive interactions might be an effective strategy to enhance Li dynamics and increase Li conductivity in a hybrid solid-state electrolyte. Although confinement within the ZIF-8 model system leads to an overall decrease in conductivity, this study provides valuable insights into the design of hybrid electrolytes for next-generation battery applications.
将离子液体与金属有机框架相结合的混合固态电解质，为提高下一代电池的安全性和能量密度提供了一种很有前景的方法。深入了解混合固态电解质中固液相之间的相互作用对于优化其作为电池电解质的性能至关重要。本研究调查了不同离子液体基电解质与金属有机框架ZIF-8之间的相互作用如何影响受限环境中锂的配位和动力学。为此，我们研究了五种不同的离子液体，改变阳离子的化学性质。利用二维固态核磁共振和模拟辅助的拉曼光谱来阐明锂的配位和离子-壁相互作用。使用锂自旋弛豫、阻抗谱和模拟研究了这些相互作用对离子液体-ZIF-8混合体系中局部锂动力学和电荷传输的影响。结果表明，锂与离子液体阳离子与ZIF-8框架之间存在竞争性相互作用，可通过改变离子液体阳离子的分子结构进行微调。因此，取决于离子液体阳离子，局部锂动力学得到增强。与本体电解质中锂传输受强锂-阴离子簇限制不同，受限体系中的有益相互作用甚至可使锂成为扩散最快的物种。因此，通过其他竞争性相互作用阻断锂-框架相互作用可能是增强混合固态电解质中锂动力学和提高锂电导率的有效策略。尽管ZIF-8模型体系中的受限导致电导率总体下降，但本研究为下一代电池应用的混合电解质设计提供了有价值的见解。
