Carbon coated bimetallic sulfides Co9S8/ZnS heterostructures microrods as advanced anode materials for lithium ion batteries

Abstract

Lithium ion batteries (LIBs) are widely used in portable electronic devices and hybrid vehicles because of their high energy density, long cycle life and environmental friendliness. Constructing bimetallic sulfide have been demonstrated as most promising strategy for prepare high performance anode materials for LIBs. However, the huge volume change resulting in poor cycle life during the change and discharge process was the key issue of transition metal sulfides. Here, bimetallic sulfide carbon micro-rods consist of Co9S8/ZnS core and outer carbon shell (Co9S8/ZnS@C MRs) is synthesized as anode materials for LIBs. Such a well-designed architecture have various advantages including the bimetallic sulfide Co9S8/ZnS heterostructures can generate built-in electric field, which boosting the ion and electron transfer at the interfaces between Co9S8 and ZnS. Moreover, the outer carbon layer can enhance the conductivity, and buffer the volume expansion of Co9S8/ZnS during the lithiation/delithiation process. As a result, combined with the merits of heterostructures and core-shell structure, the Co9S8/ZnS@C MRs exhibits outstanding electrochemical performance. Specifically, it can deliver a high capacity of 591.1 mAh g−1 after 1000 cycles at 1.0 A g−1, and maintain a capacity of 367 mAh g−1 even at 5.0 A g−1.