Electrochemical stability of optimized Si/C composites anode for lithium-ion batteries

We present a simple versatile strategy to synthesized the Si/C composites as anode material for lithium batteries through the pyrolysis of starch as the precursor. Different ratios of Si to starch are used to optimize the compound and the electrochemical properties of the composites. The structure and morphology of the Si/C composites are investigated systematically by thermogravimetric and differential thermal analysis, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electrochemical properties of Si/C composites electrode are investigated by constant current charge-discharge, cyclic voltammetry, and electrochemical impedance spectra techniques. As an anode material for lithium-ion batteries, the Si/(48 wt%)C composites exhibit the best electrochemical properties with the capacity retention of 91.3 % after 50 cycles with a current density of 100 mA g(-1). The improvement could be attributed to the introduction of carbon in the Si/(48 wt%)C composites, which can provide a rapid lithium transport pathway, reduce the cell impedance, and stabilize the electrode structure during the lithium alloying-dealloying process.