Coated/Sandwiched rGO/CoSx Composites Derived from Metal-Organic Frameworks/GO as Advanced Anode Materials for Lithium-Ion Batteries

摘要

Rational composite materials made from transition metal sulfides and reduced graphene oxide (rGO) are highly desirable for designing high-performance lithium-ion batteries (LIBs). Here, rGO-coated or sandwiched CoSx composites are fabricated through facile thermal sulfurization of metalorganic framework/GO precursors. By scrupulously changing the proportion of Co2+ and organic ligands and the solvent of the reaction system, we can tune the forms of GO as either a coating or a supporting layer. Upon testing as anode materials for LIBs, the as-prepared CoSx-rGO-CoSx and rGO@CoSx composites demonstrate brilliant electrochemical performances such as high initial specific capacities of 1248 and 1320 mAh g(-1), respectively, at a current density of 100 mA g(-1), and stable cycling abilities of 670 and 613 mAh g(-1), respectively, after 100 charge/discharge cycles, as well as superior rate capabilities. The excellent electrical conductivity and porous structure of the CoSx/rGO composites can promote Li+ transfer and mitigate internal stress during the charge/discharge process, thus significantly improving the electrochemical performance of electrode materials.