Sodium Ion Conductivity in Superionic IL-Impregnated Metal-Organic Frameworks: Enhancing Stability Through Structural Disorder
Sodium Ion Conductivity in Superionic IL-Impregnated Metal-Organic Frameworks: Enhancing Stability Through Structural Disorder
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DOI：
10.1038/s41598-020-60198-w
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发表时间：
2020-02-26
影响因子：
4.6
通讯作者：
Wondraczek, Lothar
中科院分区：
文献类型：
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作者：
Nozari, Vahid;Calahoo, Courtney;Wondraczek, Lothar
金属有机框架（MOF）是复合电解质中令人感兴趣的主体材料，因为它们能够通过化学调整MOF骨架来定制主客体相互作用。在这里，我们通过浸渍含钠盐离子液体（IL） （Na0.1EMIM0.9）TFSI，将特别高的钠离子电导率引入到沸石咪唑盐骨架ZIF-8中。我们证明了离子电导率超过2 × 10(-4) S。cm(-1)，活化能低至0.26 eV，也就是说，这是迄今为止报道的mof基复合电解质中室温Na+相关离子传导的最高性能。通过球磨使zif骨架部分非晶化，可显著增强复合材料在环境条件下的稳定性，可达20天。虽然网络无序的引入减缓了IL的渗出和与环境污染物的相互作用，但离子电导率只受到轻微影响，随着结晶度的降低而降低，但仍保持超离子行为。这突出了在MOF/IL共混物中，相互连接的孔隙三维网络对于有效离子传导的重要性，而孔隙对称是一个不那么严格的条件。
Metal-organic frameworks (MOFs) are intriguing host materials in composite electrolytes due to their ability for tailoring host-guest interactions by chemical tuning of the MOF backbone. Here, we introduce particularly high sodium ion conductivity into the zeolitic imidazolate framework ZIF-8 by impregnation with the sodium-salt-containing ionic liquid (IL) (Na0.1EMIM0.9)TFSI. We demonstrate an ionic conductivity exceeding 2 x 10(-4) S . cm(-1) at room temperature, with an activation energy as low as 0.26 eV, i.e., the highest reported performance for room temperature Na+-related ion conduction in MOF-based composite electrolytes to date. Partial amorphization of the ZIF-backbone by ball-milling results in significant enhancement of the composite stability towards exposure to ambient conditions, up to 20 days. While the introduction of network disorder decelerates IL exudation and interactions with ambient contaminants, the ion conductivity is only marginally affected, decreasing with decreasing crystallinity but still maintaining superionic behavior. This highlights the general importance of 3D networks of interconnected pores for efficient ion conduction in MOF/IL blends, whereas pore symmetry is a less stringent condition.