Facile synthesis and electrochemical performances of hollow graphene spheres as anode material for lithium-ion batteries.

Ran-Ran Yao,Li Xu,Ning-Na Yao,Dong-Lin Zhao,Li-Zhong Bai

doi:10.1186/1556-276x-9-368

Abstract

The hollow graphene oxide spheres have been successfully fabricated from graphene oxide nanosheets utilizing a water-in-oil emulsion technique, which were prepared from natural flake graphite by oxidation and ultrasonic treatment. The hollow graphene oxide spheres were reduced to hollow graphene spheres at 500°C for 3 h under an atmosphere of Ar(95%)/H2(5%). The first reversible specific capacity of the hollow graphene spheres was as high as 903 mAh g-1 at a current density of 50 mAh g-1. Even at a high current density of 500 mAh g-1, the reversible specific capacity remained at 502 mAh g-1. After 60 cycles, the reversible capacity was still kept at 652 mAh g-1 at the current density of 50 mAh g-1. These results indicate that the prepared hollow graphene spheres possess excellent electrochemical performances for lithium storage. The high rate performance of hollow graphene spheres thanks to the hollow structure, thin and porous shells consisting of graphene sheets.PACS81.05.ue; 61.48.Gh; 72.80.Vp

Highlights

Since the paper on freestanding graphene was published by Novoselov et al [1], the preparation, structure, and property of graphene have attracted great attention owing to its particular quantum Hall effect, sensitivity, mechanical hardness, electrical conductivity, and so on [2,3,4,5,6,7]
Compared with the graphene sheets [21], the prepared hollow graphene spheres (HGSs) possess better cycle and high rate performances for the lithium storage, which thanks to the hollow structure, thin and porous shells consisting of graphene sheets
After 60 cycles, it was found that the reversible capacity was still maintained at 652 mA g−1 for HGSs. These results demonstrated that the prepared HGSs have an intensive potential as a candidate of anode materials with high reversible capacity, good cycle performance, and high rate discharge/charge capability

Summary

Introduction

Since the paper on freestanding graphene was published by Novoselov et al [1], the preparation, structure, and property of graphene have attracted great attention owing to its particular quantum Hall effect, sensitivity, mechanical hardness, electrical conductivity, and so on [2,3,4,5,6,7]. Graphene is a two-dimensional one-atom-thick planar sheet of sp bonded carbon atoms, which is a basic building block for graphitic materials of all other dimensionalities It is regarded as the ‘thinnest material in the universe’ with tremendous application potential. These attractive properties of graphene generate huge interest from different scientific communities in the possible implementation of graphene in different application fields such as biomedicine, reinforced composites, sensors, catalysis, energy conversion and storage device, Nowadays, lithium-ion batteries are widely used in various electronic devices, such as notebook computers, cellular phones, camcorders, electric vehicles, and electric tools due to their superior properties such as long cycle life, high energy density, no memory effect, and environmental friendliness. Graphene sheets as anode materials were investigated and exhibited large reversible capacity [15,16,17,18,19]; it has been demonstrated that the graphene sheets of ca. 0.7 nm thickness could provide the highest storage density (with a Li4C6 stoichiometry) by density of states calculations [20]

Methods

Results

Conclusion