Synthesis of FeS 2 /CoS heterostructure microspheres as anodes for high-performance Li-ion batteries

FeS 2 /CoS and FeS 2 /CoS/C composites were synthesized by solvothermal method and following vapor phase vulcanization at mild temperature with binary oxide CoFe 2 O 4 as precursors. All FeS 2 /CoS composites prepared at different molar ratios of Fe 3+ and Co 2+ ions exhibit the similar morphology of solid microspheres. As anode materials for lithium-ion batteries (LIBs), the as-prepared FeS 2 /CoS and FeS 2 /CoS/C composites show higher reversible capacity and better cycling performance, compared with the bare FeS 2 and CoS. Among them, the FeS 2 /CoS composite with molar ratio of Fe 3+ and Co 2+ of 2:1 exhibits the high reversible capacity of 1150 mAh g −1 after 100 cycles at 100 mA g −1 and even 610 mAh g −1 at 1.0 A g −1 after 900 cycles. This strategy for synthesizing the heterogeneous structure of binary sulfide can effectively improve the kinetic which thus enhance the electrochemical performance of materials. This work can provide an effective method and idea for the preparation and modification of FeS 2 and other transition metal sulfide anode materials for LIBs in the future.