Carbon-coated mixed-metal sulfide hierarchical structure: MOF-derived synthesis and lithium-storage performances

Abstract

With the aim to satisfy the demands for future-generation lithium-ion battery (LIB) with large reversible capacity, high energy density and long-period stability, more explorations focus on the metal sulfide electrode materials. A unique hollow hierarchical sphere of sulfur-doped carbon coated FeS2/ZnS (Fe-Zn-S@S-doped-C) is demonstrated to be an effective electrode candidate for Li-ion battery in this work. In favor of the robust hollow hierarchically porous spherical structure design, the doped-S in the carbon matrix along with the synergetic effect originated from the two metal sulfide species with different Li-storage potentials, the Fe-Zn-S@S-doped-C composite exhibits large reversible capacity and long-term stability when utilized as the Li-ion battery anode material. After 200 cycles, a large capacity (1321 mAh g−1) is retained, which is substantially higher than the theoretical value of FeS2 or ZnS. The Fe-Zn-S@S-doped-C composite also delivers good rate capabilities (679 and 317 mAh g−1 at 1 and 5 A g−1, respectively). Furthermore, the kinetic analysis based on cyclic voltammograms and Galvanostatic Intermittent Titration Technique reveal the fast lithium-storage kinetics of the Fe-Zn-S@S-doped-C electrode, which is largely originated from the dominated pseudocapacitive contribution.