Multifunctional hosts of Zinc sulfide coated carbon nanotubes for lithium sulfur batteries

Abstract

Lithium sulfur (Li–S) batteries are next general energy storage systems due to their high thereotical energy density, low cost and environmental friendly. Herein, we develop a composite polysulfide mediator based on carbon nanotubes enwrapped by zinc sulfide (CNTs@ZnS) nanoparticles as multifunctional host materials for sulfur cathode. The ZnS nanoparticles is uniformed coating on the outside layer of functionalized carbon nanotubes. The unique structure of CNTs@ZnS ensure the chemical adsorption on ZnS and fast electron transfer from ZnS to carbonnanotubes. The presence of ZnS efficiently alleviates the shuttle effect of soluble lithium polysulfide intermediates and hence offers a mean to further enhancing the reaction activity via sulfophilic property of ZnS and catalytically accelerate the conversion of polysulfides to insoluable Li2S. The high conductivity of carbon nanotubes results in rapid electron transfer. The CNTs@ZnS cathode offers an excellent specific capacity of ~ 1003 mAh g−1 after 100 cycles at 0.2C. Furthermore significant cycling performance at 0.2C with 3.1 mg cm−2 sulfur loading for 500 cycles is observed with 0.05% capacitance decay per cycle. The results provide insights to develop high-performance Li–S batteries based on multifunctional host materials.