Preparation and electrochemical properties of binary SixSb immiscible alloy for lithium ion batteries

The novel binary SixSb immiscible alloy was synthesized using chemical reduction-mechanical alloying methods and first investigated as possible anodes for lithium ion batteries. The microstructures, morphologies and electrochemical properties were investigated utilizing X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), constant-current charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Results showed that tiny Si particles were dispersed homogeneously in Sb active matrix. Cyclic voltammetry results indicated that the Li+-transport rates were significantly enhanced in the SixSb immiscible alloy. Results also showed that the Si0.8Sb exhibited the best cyclability with a reversible capacity of 596.4 mAh g−1 after 50 cycles. The cyclability can be improved by restricting either the upper or lower cutoff voltage, which can control the lithiation/delithiation degree and prevented the powdering and shredding of the active materials after Li+ trapped into electrode materials.