Electrochemical performance of Si/CeO₂/Polyaniline composites as anode materials for lithium ion batteries

Si has very high theoretical specific capacity as an anode material in a lithium ion battery. However, its application is seriously restricted because of relatively undesirable conductivity and poor cycling stability. Here we report Si/CeO₂/Polyaniline (SCP) composite as an anode material, which was synthesized by hydrothermal reaction and chemical polymerization. The structures and morphologies of the SCP composites are characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). It is shown that Si/CeO₂ (SC) particles are well coated by PANI elastomer which has good electrical conductivity. The SCP shows larger reversible capacity and better cycling performance compared with pure Si. The first reason is that CeO₂ can protect Si from reacting with electrolyte. More importantly, the PANI elastomer can accommodate the volume change of the composite during Li-alloying/dealloying processes, so the pulverization of silicon would be significantly reduced. The SCP material can retain a capacity nearly 775 mAh/g after 100 cycles, while pure Si only shows a capacity of 370 mAh/g after 100 cycles.