Sulfur-Doped Carbon-Wrapped Heterogeneous Fe3O4/Fe7S8/C Nanoplates as Stable Anode for Lithium-Ion Batteries

High-capacity electrode materials have attracted tremendous attention in energy storage systems. However, the large volume expansion always causes breakdown of electrode materials and capacity fading. In this work, we report the preparation of heterogeneous Fe3O4/Fe7S8/C nanoplates with a high lithium diffusion coefficient and excellent lithium storage performance. The heterogeneous nanoplates can be derived from Fe-MOF octahedra during the sulfidation process. As an anode for lithium-ion batteries, the Fe3O4/Fe7S8/C composite exhibits higher specific capacity and better rate capability than Fe3O4/C and Fe7S8/C counterparts. The Fe3O4/Fe7S8/C nanoplates deliver a reversible capacity of 859 mA h g(-1) after 100 cycles at 0.1 A g(-1). Even at 2 A g(-1), a capacity of 549 mA h g(-1) can still be remained. The good performances are attributed to the small nanocrystallites, high surface area, and the heterogeneous phase boundaries. The strategy can be potentially applied to other metal oxide/metal sulfide composite phases or even bimetallic sulfides and bimetal oxides for high performance lithium-ion batteries.