Preparation of Silicon Oxide-Carbon Composite with Tailored Electrochemical Properties for Anode in Lithium-Ion Batteries

For high-efficiency and high-stability lithium ion batteries, a silicon oxide-based carbon composite has been developed as an anode material. To minimize structural defects (cracking and pulverization) due to volumetric contraction/expansion during charge/discharge, silicon oxide (SiOx) is adopted. A pitch—a carbon precursor—is introduced to the surface of SiOx using the mechanofusion method. The introduced pitch precursor can be readily transformed into a carbon layer through stabilization and carbonization processes, resulting in SiOx@C. This carbon layer plays a crucial role in buffering the volume expansion of SiOx during lithiation/delithiation processes, enhancing electrical conductivity, and preventing direct contact with the electrolyte. In order to improve the capacity and cycle stability of SiOx, the electrochemical performances of SiOx@C composites are comparatively analyzed according to the mixing ratio of SiOx and pitch, as well as the loading amount in the anode material. Compared to pristine SiOx, the SiOx@C composite prepared through the optimization of the experimental conditions exhibits approximately 1.6 and 1.8 times higher discharge capacity and initial coulombic efficiency, respectively. In addition, it shows excellent capacity retention and cycle stability, even after more than 300 charge and discharge tests.