Synthesis and Characterization of Silicon Nanoparticles Inserted into Graphene Sheets as High Performance Anode Material for Lithium Ion Batteries

Yong Chen,Xi Zhao,Yanhong Tian,Xuejun Zhang

doi:10.1155/2014/734751

Yong Chen, Xi Zhao + Show 2 more

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https://doi.org/10.1155/2014/734751

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Abstract

Silicon nanoparticles have been successfully inserted into graphene sheets via a novel method combining freeze-drying and thermal reduction. The structure, electrochemical performance, and cycling stability of this anode material were characterized by SEM, X-ray diffraction (XRD), charge/discharge cycling, and cyclic voltammetry (CV). CV showed that the Si/graphene nanocomposite exhibits remarkably enhanced cycling performance and rate performance compared with bare Si nanoparticles for lithium ion batteries. XRD and SEM showed that silicon nanoparticles inserted into graphene sheets were homogeneous and had better layered structure than the bare silicon nanoparticles. Graphene sheets improved high rate discharge capacity and long cycle-life performance. The initial capacity of the Si nanoparticles/graphene keeps above 850 mAhg−1after 100 cycles at a rate of 100 mAg−1. The excellent cycle performances are caused by the good structure of the composites, which ensured uniform electronic conducting sheet and intensified the cohesion force of binder and collector, respectively.

Highlights

During the past decade, secondary lithium ion batteries (LIBs) have become the major power source for mobile applications, such as cellular phones, digital cameras, and notebooks [1, 2]
The pattern of Si/graphene composites is the same as that of pure Si nanoparticles, implying that the silicon crystals in the Si/graphene composites are not destroyed during the freezedrying and thermal reduction processes
In the X-ray diffraction (XRD) pattern of the graphene sample obtained with the same procedure of Si/graphene, the characteristic peak appears at 25.41, corresponding to a layer-to-layer distance (d-spacing) of 0.338 nm, which is close to the d-spacing of the natural graphite

Summary

Introduction

Secondary lithium ion batteries (LIBs) have become the major power source for mobile applications, such as cellular phones, digital cameras, and notebooks [1, 2]. The graphene-film layers could isolate all Si nanoparticles, circumventing the Si aggregation problem As a result, this facile approach can provide optimized graphene/Si nanoarchitectures where the graphene layers function as flexible mechanical support to mitigate and accommodate the volumetric-change-induced stresses/strains in the Si nanoparticles and can alleviate or even avoid the pulverization of Si phase, maintaining the structural integrity of the electrodes at the same time. This facile approach can provide optimized graphene/Si nanoarchitectures where the graphene layers function as flexible mechanical support to mitigate and accommodate the volumetric-change-induced stresses/strains in the Si nanoparticles and can alleviate or even avoid the pulverization of Si phase, maintaining the structural integrity of the electrodes at the same time This reinforcing material offers an efficient, electrically conducting medium and effectively improves the adhesion strength between different active materials and with Cu foil current collector [24]. These Si nanoparticles/graphene multilayer structure anodes exhibit a high reversible capacity and good capacity retention in both Li half cells and full cells

Experimental

Results and Discussion

Conclusion