RGO-Coated MOF-Derived In2Se3 as a High-Performance Anode for Sodium-Ion Batteries

MOF-derived metal selenides are promising candidates as effective anode materials in sodium-ion batteries (SIBs) owing to their ordered carbon skeleton structure and the high conductivity of selenides. They can be imparted with rapid electron/ion transport channels for the insertion/de-insertion of Na+. In this study, MOF- derived In2Se3 was prepared as an anode material for SIBs. However, the large volume expansion during cycling leads to structural collapse, which affects the charging and discharging circulation life of the battery. To address this, a two-dimensional rGO network was introduced on the MOF-derived In2Se3 surface by surface modification. Field-emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) results confirmed the successful synthesis of the In2Se3@C/rGO composite. The structures with two types of carbon enhanced the charge transfer kinetics and provided two stress-buffering layers. Thus, the volume change could be accommodated and simultaneously, electron transfer was accelerated. This technique was effective, as proved by the enhanced capacity retention of 95.2% at 1 A center dot g-1 after 500 cycles. In contrast, the capacity retention of the MOF-derived material without rGO was only 74.2%. Additionally, due to the synergistic effect of the rGO network and the MOF-derived In2Se3, the anode showed a superior capacity of 468 mAh center dot g-1 at 0.1 A center dot g-1. Conversely, at the same current density, the uncoated material delivered only a capacity of 393 mAh center dot g-1. To study the electrochemical process of the electrode, the In2Se3@C/rGO electrode was subjected to cyclic voltammetry (CV) measurements; the results showed that the In2Se3@C/rGO electrode had notable electrochemical reactivity. In addition, in situ X-ray diffraction (XRD) was performed to explore the sodium storage mechanism of In2Se3, demonstrating that In2Se3 had a dual Na+ storage mechanism involving conversion and alloying reactions, and revealing the origin of its high theoretical specific capacity. This study is expected to serve as a reference for preparing optimized rGO-based materials for use as SIB anodes.