Electrochemical performance of graphite/silicon/pitch anode composite prepared by metal etching process

The electrochemical characteristics of graphite/silicon/pitch composites were investigated as anode material in lithium ion batteries. The anode materials were prepared with etched graphite using nickel chloride hexahydrate. Scanning electron microscopy, x-ray diffraction and thermogravimetric analysis were used to analyze the physical properties of graphite/silicon/pitch composites. The electrochemical characteristics of the batteries were investigated by charge-discharge cycle, rate performance, cyclic voltammetry and electrochemical impedance spectroscopy tests in the eletrolyte of 1.0 M LiPF6 (EC:DMC:DEC=1:1:1vol%). Graphite/silicon/pitch electrode showed better electrochemical properties than the graphite electrode, and even nickel etched graphite was superior to graphite. Also, it was confirmed that both capacity and rate performance are significantly improved when the ratio of graphite, silicon, and pitch is 8:1:1 (G8Si1P1). It is found that G8Si1P1 has the initial discharge capacity of 680 mAh/g, the capacity retention ratio of 90% during 100 cycles and the retention rate capability of 91% in 2 C/0.1 C, 87% in 5 C/0.1 C.