Amorphous/crystalline heterostructured indium (III) sulfide/carbon with favorable kinetics and high capacity for lithium storage

Abstract

Nanostructured metal sulfides (MSs) are considered prospective anodes for Li-ion batteries (LIBs) due to their high specific capacity and abundant raw materials on Earth. Nevertheless, the poor conductivity and volume expansion hinder their application. Here, we report the design of amorphous/crystalline indium sulfide nanotubes coated by carbon, in which MIL-68 (In) metal–organic frameworks (MOF) are used as a precursor to generate In₂S₃/carbon (In₂S₃/C) through a solvothermal process. The construction of amorphous/crystalline structure not only combines the advantages of abundant ion channels of amorphous structure, but also has high crystal conductivity and promotes ion transport. The In₂S₃/C anode of LIBs exhibits excellent performance of 835 mAh g⁻¹ at the current density of 0.5 A g⁻¹ after 500 cycles. In₂S₃/C also shows outstanding long-term performance with 717 mAh g⁻¹ at 2 A g⁻¹. The lithium storage mechanism is elucidated through kinetic analysis and ex situ X-ray photoelectron spectroscopy investigations. Further density functional theory (DFT) calculations indicate that In₂S₃/C electrodes have low adsorption energies and fast diffusion kinetics. In a word, the MOF-derived amorphous/crystalline In₂S₃/C exhibits better electrochemical performances than commercial In₂S₃. This research will inspire the exploration of MSs as well as detect potential “diamonds in the rough.”