Enhanced Performance of Lithium Sulfur Battery with a Reduced Graphene Oxide Coating Separator

Abstract

In this study, the separator coated with reduced graphene oxide (rGO) layer is prepared via doctor blading. The lithium-sulfur (Li-S) battery with rGO-coated separator exhibits much smaller impedance and much better electrochemical performance. After coated rGO, the initial discharge capacity can be as large as 1067 mAh g−1 at 0.2 C which can retain 878 mAh g−1 after 100 cycles, and the discharge capacity can reach 710 mAh g−1 even at 2 C. The significant performance enhancement can be attributed to the bi-functionality of rGO; the rGO coating layer has unique porous structure, high conductivity and various kinds of functional groups, which can not only effectively prevent the diffusion of polysulfide through the separator, but also significantly increase the conducting surface between cathode and separator. It is promising to use rGO-based slurry to continuously produce large-scale, low-cost, and bi-functional rGO coated separator for high-performance Li-S batteries.