Electrochemical properties of negative SiMox electrodes deposited on a roughened substrate for rechargeable lithium batteries

To replace conventional carbon, silicon has been widely proposed as a next-generation negative electrode (anode) material for lithium-ion batteries. In this study, Si and SiMox-alloy deposited by an RF-magnetron sputtering system is investigated by means of X-ray diffraction, ex situ Raman spectroscopy and transmission electron microscopy. Electrochemical tests are conducted and four different Si and SiMox-alloy electrodes and their structures and textual properties are characterized with X-ray photoelectron spectroscopy. The surface morphologies of the electrodes are also observed using field-emission scanning electron microscopy. The electrochemical properties of the electrodes are examined through cycling tests and electrochemical impedance spectroscopy. The results show that rough Cu foil and Mo as alloy materials help Si to retain its discharge capacity and overcome volume expansion during charging and discharging. After a few cycles, the Si electrode severely loses capacity, whereas the SiMox-alloy electrodes display good cycle retention and high capacity. The SiMo0.79 electrode gives an initial capacity of 1319 mAh g−1 that decreases to 1180 mAh g−1 after 100 cycles (89.4%).