Structural Regulation of Coordination Supramolecular Networks for Remarkable Lithium Storage

The search for high-energy and fast Li-ion transportation of lithium-ion battery (LIB) anode materials instead of graphite has aroused the wide attention of scientists. Coordination supramolecular networks (CSNs) are a class of active materials that can be used in energy storage devices because of their adjustable structural characteristics and various intermolecular forces. In this work, 1D-CoCSN {[Co3(stp)2(bpy)5(H2O)6]n} and 3D-CoCSN {[Co3(stp)2(bpy)(H2O)4]n} were synthesized by regulating the coordination reaction of 2-sulfoterephthalic acid monosodium salt (NaH2stp), 4,4 '- bipyridine (bpy), and cobalt ions. The X-ray photoelectron spectroscopy (XPS), ex situ Fourier transform infrared spectroscopy (FTIR), and density functional theory (DFT) analyses show that the carboxylic, sulfonic, and pyridine active groups of 1D-CoCSN are synergically involved in the storage process of lithium ions, and electrons could be transferred in the Z-shaped chain structure through the pi-d-pi conjugation effect. Hence, 1D-CoCSN exhibits a high capacity of 567 mAh g-1 after 200 cycles at 0.5 A g-1 and even runs 1000 cycles at 2 A g-1 with a capacity of 233 mAh g-1. Structural regulation of CSNs provides a new approach to designing LIB anodes with high capacity and stable cycling performance.