Hollow cubic ZnS-SnS2 heterostructures as sulfur hosts to enhance chemisorption and catalytic conversion of polysulfides for lithium sulfur batteries

The low utilization of the active substance sulfur and the slow kinetic process of polysulfide are great obstacles to the development of lithium-sulfur (Li-S) batteries. In this work, a hollow cubic heterostructure ZnS-SnS2 (ZSS) was prepared by a simple co-precipitation method and in situ vulcanization. Firstly, the internal hollow cavity structure is easier to take advantage of the sulfur carrier as well as to maintain the stability of the structure during the battery's cycle. Secondly, The ZSS heterostructure is unique in enhancing the redox activity of polysulfides. This is manifested in three levels of adsorption-diffusion-transformation with SnS2 as the main adsorption site, a heterogeneous interface as the diffusion center, and ZnS as the catalytic conversion core. Multifunctional systems were established to effectively immobilize and release polysulfides, facilitate the diffusion of lithium ions, and reduce the energy barriers to S reduction and Li2S oxidation. Apparently, Benefit from the unique structure and complex composition of ZSS, the ZSS@S cathode exhibits excellent multiplicative performance with initial discharge specific capacity of 1252.8 mAh/g at 0.1C and 635.7 mAh/g at 5C. It also has high reversibility, maintaining a low decay of 0.071 % per cycle after 500 cycles at 2C. In addition, the ZSS heterostructure also exhibits excellent electrochemical performance even under high sulfur loading and poor electrolyte system.

Automated summary

In this study, a hollow cubic heterostructure ZnS-SnS2 (ZSS) was prepared by a simple co-precipitation method and in situ vulcanization, which successfully addressed the low utilization of sulfur and slow kinetic process of polysulfide in Li-S batteries. The unique ZSS heterostructure enhanced the redox activity of polysulfides through a three-level adsorption-diffusion-transformation structure, establishing multifunctional systems to immobilize and release polysulfides and facilitate the diffusion of lithium ions.