Few-layer graphene prepared via microwave digestion reduction and its electrochemical performances in lithium ion batteries

A simple approach is proposed to prepare graphene sheets by microwave digestion reduced graphene oxide without any auxiliary reagents. This method is easily controlled and the graphene oxide as graphene precursor is not must be washed to neutral. The materials are characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties of graphene sheets anode for lithium ion batteries are studied by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge. The graphene as an anode material exhibits high capacity and excellent electrochemical performance in lithium ion batteries. The first discharge/charge capacities are 2113.8/1069.3 mA h g^-1 at current densities of 100 mA g^-1, and the reversible specific capacities remain 733.3 mA h g^-1 after 100 cycles. The graphene sheets electrode shows excellent lithium storage properties at large current densities. The possible mechanism preparation is analyzed. The microwave digestion can reduce the reaction activation energy and change reaction kinetics. In this reaction, overheated supercritical water can play the role of reducing agent and offers a green chemistry alternative to organic solvents.