Redox-Active Two-Dimensional Tetrathiafulvalene-Copper Metal–Organic Framework with Boosted Electrochemical Performances for Supercapatteries

Metal–organic frameworks (MOFs) have attracted noticeable attention as promising candidates for electrochemical energy storage. However, the lack of electrical conductivity and the weak stability of most MOFs result in poor electrochemical performances. Here, a tetrathiafulvalene (TTF)-based complex, formulated as [(CuCN)2(TTF(py)4)] (1) (TTF-(py)4= tetra(4-pyridyl)-TTF), is assembled by in situ generation of coordinated CN–from a nontoxic source. Single-crystal X-ray diffraction analysis reveals that compound 1possesses a two-dimensional layered planar structure, which is further stacked in parallel to form a three-dimensional supramolecular framework. The planar coordination environment of 1is the first example of a TTF-based MOF. Attributed to the unique structure and redox TTF ligand, the electrical conductivity of 1is significantly increased by 5 orders of magnitude upon iodine treatment. The iodine-treated 1(1-ox) electrode displays typical battery-type behavior through electrochemical characterizations. The supercapattery based on the 1-oxpositrode and AC negatrode presents a high specific capacity of 266.5 C g–1at a specific current of 1 A g–1with a remarkable specific energy of 62.9 Wh kg–1at a specific power of 1.1 kW kg–1. The excellent electrochemical performance of 1-oxis one of the best among those reported supercapatteries, demonstrating a new strategy for developing MOF-based electrode materials.