Preparation of porous SiOx/TiO2 anode with PDMS using plasma electrolytic oxidation

초록

Silicon is attracting great attention as a next-generation high-capacity anode material to replace commercial graphite due to its higher theoretical capacity (4200 mAh g-1) than that of graphite (372 mAh g-1). However, silicon anode faces several problems including cracking of the electrode and electrolytes consumption caused by a large volume expansion of ~400% during Li insertion and extraction processes. On the contrary, TiO2 has a relative small theoretical capacity (175 mAh g-1) but shows almost zero volume expansion (~5%). In this study, we report the preparation of SiOx/TiO2 composite based on a plasma electrolytic oxidation (PEO) approach, aiming at achieving the anode with high theoretical capacity and excellent cycle stability. With an applied voltage of 160-200 V in a mixed solution of H2SO4-Na2SiO3, we successfully produced the composite film. We show that a relatively lower voltage is required to produce PEO film when a Ti substrate is covered by polydimethylsiloane (PDMS) via spin coating before anodization. The surface structure and physicochemical properties are evaluated through the scanning electron microscope-energy dispersion X-ray spectroscopy (SEM-EDX), X-ray diffraction analyzer (XRD) and photoelectron spectrometer (XPS). Furthermore, the electrochemical performances are evaluated via half-cell type configuration.