Polar mesoporous zinc sulfide nanosheets encapsulated in reduced graphene oxide three-dimensional foams for sulfur host

Limin Mao,Jian Mao,Fei Wang

doi:10.1038/s41598-020-62037-4

Abstract

Lithium-sulfur (Li-S) batteries exhibit the high specific capacity and energy density, but prevented by the low coulombic efficiency and weak cycle life. Herein, we fabricate reduced graphene oxide (r-GO) three-dimensional (3D) foams encapsulating polar mesoporous zinc sulfide (ZnS) nanosheets and subsequently utilize the ZnS/r-GO foams to load sulfur (ZnS/r-GO/S) as cathodes for improving the performance of Li-S batteries. The mesoporous diameter of the ZnS nanosheets is approximately 10~30 nm and lots of pores in the 3D foams are observed. The porous structure provides abundant sites to adsorb and accommodate sulfur species. The cathode of the ZnS/r-GO/S exhibits 1259 mA h g−1 of initial capacity and 971.9 mA h g−1 of the reversible capacity after 200 cycles at 0.1 C (1 C = 1675 mA g−1). At 1 C, it still exhibits the tiny capacity decay rate of 0.019% per cycle after 300 cycles. This work may be adopted to combine the nonpolar and polar materials as a 3D network structure for high-performance Li-S batteries.

Highlights

Lithium-sulfur (Li-S) batteries exhibit the high specific capacity and energy density, but prevented by the low coulombic efficiency and weak cycle life
The zinc sulfide (ZnS)(en)0.5 was composed of large quantities of smooth nanosheets with the thickness of 60~100 nm, and the large range of a few to a dozen micrometers in lateral dimensions (Fig. 2a).The mesoporous ZnS succeeded to the similar sheet nanostructure in Fig. 2b, and the porosities were triggered by the decomposition of ethylenediamine (EDA)[32], which could provide more sites to adsorb and catalyze polysulfides
The SEM of the ZnS/reduced graphene oxide (r-GO) foams (Fig. 2d) indicated that the ZnS nanosheets were encapsulated in the r-GO foams

Summary

Introduction

Lithium-sulfur (Li-S) batteries exhibit the high specific capacity and energy density, but prevented by the low coulombic efficiency and weak cycle life. We designed a three-dimensional (3D) porous foams, constructed by high conductive reduced graphene oxide (r-GO), to encapsulate polar mesoporous ZnS nanosheets by a facile water bath method. The ZnS/r-GO foams loaded sulfur as composite electrodes for high-performance Li-S batteries.

Results

Conclusion