A novel lithium/sulfur battery based on sulfur/graphene nanosheet composite cathode and gel polymer electrolyte

Yongguang Zhang,Zhumabay Bakenov,Yan Zhao

doi:10.1186/1556-276x-9-137

Yongguang Zhang, Zhumabay Bakenov + Show 1 more

Open Access

https://doi.org/10.1186/1556-276x-9-137

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Abstract

A novel sulfur/graphene nanosheet (S/GNS) composite was prepared via a simple ball milling of sulfur with commercial multi-layer graphene nanosheet, followed by a heat treatment. High-resolution transmission and scanning electronic microscopy observations showed the formation of irregularly interlaced nanosheet-like structure consisting of graphene with uniform sulfur coating on its surface. The electrochemical properties of the resulting composite cathode were investigated in a lithium cell with a gel polymer electrolyte (GPE) prepared by trapping 1 mol dm−3 solution of lithium bistrifluoromethanesulfonamide in tetraethylene glycol dimethyl ether in a polymer matrix composed of poly(vinylidene fluoride-co-hexafluoropropylene)/poly(methylmethacrylate)/silicon dioxide (PVDF-HFP/PMMA/SiO2). The GPE battery delivered reversible discharge capacities of 809 and 413 mAh g−1 at the 1st and 50th cycles at 0.2C, respectively, along with a high coulombic efficiency over 50 cycles. This performance enhancement of the cell was attributed to the suppression of the polysulfide shuttle effect by a collective effect of S/GNS composite cathode and GPE, providing a higher sulfur utilization.

Highlights

Lithium-ion batteries are leading power sources for portable applications from small consumer electronics to electricity-powered transport
We report on the preparation of a novel sulfur/graphene nanosheet (S/GNS) composite via a simple ball milling of sulfur and commercial multi-layer graphene nanosheets, followed by a heat treatment, and investigation of its physical and electrochemical properties as a cathode for Li|S batteries
The size reduction of graphene and formation of disordered and hollow structure of the composite agglomerates create the pathways for the electrolyte and Li-ion transport providing enhanced activity of the composite. These structural advantages of the composite are favorable for the cathode rate capability, which was further observed in the electrochemical studies

Summary

Introduction

Lithium-ion batteries are leading power sources for portable applications from small consumer electronics to electricity-powered transport. Their wider application is restricted due to the limited energy density of available cathode materials. Alternative cathode materials with high energy density and low cost are needed [1]. Sulfur is very attractive as a cathode material for the next-generation high-energy rechargeable lithium batteries because of its advantages of a large theoretical capacity of 1,672 mAh g−1, which is the highest among all known cathode materials, low cost, and environmental friendliness [2,3,4]. The preparation techniques used to obtain these materials have the disadvantages of side products and prolonged and complicated processing, increasing the final product cost [10]

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