Fe3Se4 decorating carbon nanotubes with superior sodium storage performance for sodium-ion batteries

Due to the ideal theoretical capacity, high initial coulombic efficiency, satisfactory electronic conductivity, and environmental friendliness, iron-based selenides have been intensively explored and developed as anodes for sodium-ion batteries (SIBs). However, they still face numerous obstacles in the commercialization process, such as large volume changes. In this work, a nanocomposite of Fe3Se4 decorated carbon nanotubes (Fe3Se4/CNTs) was designed and prepared through a simple solvothermal method and subsequent selenization process. SEM and TEM images manifest that the Fe3Se4 nanoparticles are well anchored to the two-dimensional CNTs. In the composite, Fe3Se4 can provide high sodium storage capacity, meanwhile, CNTs acts as a self-supporting framework, which effectively enhances the electronic conductivity and mitigates the drastic volume expansion of Fe3Se4/CNTs electrode during electrochemical process. Thus, the Fe3Se4/CNTs electrode presents satisfactory sodium storage capacity and cycling stability. At 1 A g−1, it delivers a high capacity of 424 mA h g−1 after 500 cycles, with a superior capacity retention of ~100 %. In addition, cyclic voltammetry (CV), galvanostatic intermittent titration (GITT), and ex-situ X-ray diffraction (XRD) were employed to analyze the sodium storage mechanism and sodium ion diffusion ability in the Fe3Se4/CNTs electrode. This work provides an effective method for developing high-performance anodes for SIBs.