Metal-Organic Frameworks for Rechargeable Batteries

Dühnen S, Heckmann A, Winter M, Placke T

Abstract

In the last years, metal-organic frameworks (MOFs) have emerged as a versatile and promising class of materials for battery electrodes. They offer a crystalline structure composed of inorganic ions or clusters (often referred as "SBU": "secondary building unit") coordinated to multivalent organic molecules, also called "linker". Due to the inorganic/organic hybrid structure, MOFs exhibit well-dispersed metal centers separated by organic linkers which can be modified with a variety of functional groups. Most MOFs have a microporous structure with pore sizes tailorable by the length of the incorporated linker molecules. In some cases, the inorganic/organic hybrid framework of MOFs can show reversible structural changes due to the insertion of guest molecules (e.g. solvent molecules) resulting in flexible crystal structures. Since the pore size as well as the pore environments can be tailored in manifold ways, MOFs are an interesting material for battery applications, such as lithium ion batteries or dual-ion batteries.[1],[2] MOFs can be designed particularly for lithium insertion on the negative or positive electrode and/or for anion insertion on the positive electrode. Small pore sizes and advantageous functional groups of the linker could improve the insertion of lithium ions on the one hand, whereas larger pore sizes and wide pore openings could lead to a reversible anion insertion process on the other hand. In this work, we have synthesized iron-based MOFs with different linker molecules to investigate the influence of the linker molecule on the insertion process of lithium ions and large anions. The multi-valent Fe(III)/Fe(II) inorganic cluster of the Fe-MOFs undergoes a reversible redox reaction during charge and discharge cycles. The MOF-based composite electrodes can be prepared via electrode paste coating process which makes MOF materials readily adaptable for an up-scaled battery electrode production. [1] Wang, L.; Han, Y.; Feng, X.; Zhou, J.; Qi, P.; Wang, B., Metal-organic frameworks for energy storage: Batteries and supercapacitors. Coordination Chemistry Reviews 2016, 307, 361-381 [2] Aubrey, M. L.; Long, J. R., A Dual-Ion Battery Cathode via Oxidative Insertion of Anions in a Metal-Organic Framework. Journal of the American Chemical Society 2015, 137 (42), 13594-13602. [TP1]Hier würde ich 1-2 REFs einfügen [TP2]Diesen Teil würde ich etwas kürzen...