Investigation of electrochemical reaction mechanism for antimony selenide nanocomposite for sodium-ion battery electrodes

Antimony selenide and its carbon composite were synthesized through a mechanochemical process and investigated as anode materials for sodium-ion secondary batteries. X-ray diffraction (XRD) with rietveld refinement and transmission electron microscopy (TEM) analyses confirm that Sb 2 Se 3 were composed of agglomerated highly crystalline nanocrystallites and the Sb 2 Se 3 /C composite consisted of nanocrystalline Sb 2 Se 3 dispersed homogeneously throughout an amorphized carbon matrix. The initial Coulombic efficiency, rate capability, and cycle performance of the Sb 2 Se 3 /C composite were superior to those of Sb, or Sb 2 Se 3 . The Sb 2 Se 3 /C composite, in particular, showed excellent cycle stability, with 98.2% of initial capacity at 200 mA g −1 after 200 cycles. Based on the reaction potentials, ex situ XRD patterns and ex situ HR-TEM analysis of the Sb 2 Se 3 /C composite electrode revealed the structural changes which occurred reversibly within the Sb 2 Se 3 /C composite by conversion and recombination reaction during sodiation and desodiation process. Furthermore, XPS analysis study was carried out for identifying the surface films formed on both the electrodes and their effects on the performances. Graphical abstract