Hybrid Graphene Album with Polysulfides Adsorption Layer for Li-S Batteries

Xiaodong Hong, Ji Liang, Xiaonan Tang, Huicong Yang, Feng Li

Index: 10.1016/j.ces.2018.03.027

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Abstract

Lithium-sulfur (Li-S) battery is a promising candidate for the next-generation power sources due to their low-cost and high energy density. However, the shuttle effect of the dissolved polysulfides in the electrolyte solvents has hindered the commercialization of Li-S batteries. In order to effectively suppress the shuttle effect, we design and prepare a bybrid graphene album structure as an efficient polysulfides-trapped host for Li-S battery. In this composite, the graphene album structure is stacked by graphene layer by layer through a bottom-up assembly, which provides a hierarchical porous structure, easy mass transport and excellent conductivity for the cathode host of Li-S batteries. The uniform g-C3N4 layer was in-situ generated on each graphene by hydrothermal treatment and heat polycondensation. The orderly bybrid graphene album (coded as g-C3N4@n-G) achieves the two-dimensional surface adsorption interaction for imobilizing soluble polysulfides, and the multilayer barriers also effectively prevent the escape of polysulfides to enhance the long cycling stability of Li-S batteries. As a result, an extremely low capacity decay of 0.028% cycle-1 and a high initial capacity of 1252 mA h g-1 have been achieved at 0.2 C. Furthermore, this kind of unique design and preparation method for hybrid graphene album also opens an opportunity for the construction of other album-like graphene-based hybrids.