Iron–zinc sulfide Fe2Zn3S5/Fe1−xS@C derived from a metal–organic framework as a high performance anode material for lithium-ion batteries

Abstract

Bimetallic sulfides deliver redox reactions and provide a buffer effect during electrochemical reactions, and thus have been the focus of research in the field of energy storage materials. Herein, a carbon cage coated bimetallic sulfide (Fe₂Zn₃S₅/Fe_1−xS@C) composite with a heterogeneous structure was synthesized by using a metal–organic framework (Fe^III-MOF-5) as a self-sacrificial template. The composite nanoparticles were monodispersed and encapsulated in a carbon cage. This setup ensured excellent performance by improving electrical conductivity and preventing the dissolution of polysulfide intermediates. In situ X-ray diffraction (In situ XRD) and cyclic voltammetry (CV) test results indicate that conversion reactions occur during charging and discharging processes. When tested in coin cells, the composite material exhibited excellent cycling and rate performances, demonstrating high reversible capacities of 2071.2 mA h g⁻¹ at a current density of 500 mA g⁻¹ after 700 cycles and 736.1 mA h g⁻¹ at a current density of 5000 mA g⁻¹ after 700 cycles. The results indicate that the composite derived from Fe^III-MOF-5 is a promising high-performance anode material for lithium-ion batteries.