Novel synthesis of holey reduced graphene oxide (HRGO) by microwave irradiation method for anode in lithium-ion batteries.

Edreese Alsharaeh,Hatem Abuhimd,Majdi Khasawneh,Faheem Ahmed,Yazeed Aldawsari,Mohammad Alshahrani

doi:10.1038/srep29854

Abstract

In this work, holey reduced graphene oxide (HRGO) was synthesized by the deposition of silver (Ag) nanoparticles onto the reduced graphene oxide (RGO) sheets followed by nitric acid treatment to remove Ag nanoparticles by microwave irradiation to form a porous structure. The HRGO were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultra violet-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), and Raman spectroscopy. These novel HRGO exhibited high rate capability with excellent cycling stability as an anode material for lithium-ion batteries. The results have shown an excellent electrochemical response in terms of charge/discharge capacity (423 mAh/g at 100 mA/g). The cyclic performance was also exceptional as a high reversible capacity (400 mAh/g at 100 mA/g) was retained for 100 charge/discharge cycles. This fascinating electrochemical performance can be ascribed to their specific porous structure (2–5 nm pores) and high surface area (457 m2/g), providing numerous active sites for Li+ insertion, high electrical conductivity, low charge-transfer resistance across the electrolyte–electrode interface, and improved structural stability against the local volume change during Li+ insertion–extraction. Such electrodes are envisioned to be mass scalable with relatively simple and low-cost fabrication procedures, thereby providing a clear pathway toward commercialization.

Highlights

In this work, holey reduced graphene oxide (HRGO) was synthesized by the deposition of silver (Ag) nanoparticles onto the reduced graphene oxide (RGO) sheets followed by nitric acid treatment to remove Ag nanoparticles by microwave irradiation to form a porous structure
Despite the holey properties of the starting graphene sample, such as electron mobility, electrical conductivity, thermal conductivity, and mechanical properties, should be largely preserved. It is these properties of graphene that make it such an attractive material, so the fact that the HRGO samples retain them is very important for their subsequent applications that are dependent upon these properties[33]
A novel microwave irradiation method combined with Ag nanoparticles deposition on the RGO sheets and acid treatment procedure has been used for the fabrication of HRGO

Summary

Results and Discussion

It is clear from galvanostatic charge/discharge curves of RGO without holes as shown in Fig. 13 that the discharge capacity of 164 mAh/g for the 1st cycle was observed, which is ~2.5 fold less than the discharge capacity of HRGO This indicates that the holes in HRGO facilitate the transport of lithium ions in HRGO, allowing a better access of the graphene structure to the electrolyte. The porous structure of HRGO can greatly reduce the effective diffusion distance for the Li ions and buffer against the local volume change during Li insertion–extraction, resulting in greatly improved rate capability and cycling stability This along with its large surface area, which provides more active sites for Li insertion, greatly increases the performance of the HRGO anode

Conclusions

Author Contributions

Additional Information