Enhanced cycle capacity retention of plasma-sprayed SiOxnanocomposite powders for negative electrode of lithium ion batteries

Core–shell SiOx nanocomposite powders have been produced in a single continuous plasma spray process. The addition of CH4 at appropriate amounts during plasma spraying of SiO was found to be quite effective in promoting the reduction of SiO and thus increasing the crystalline Si amount after the disproportionation reaction. The half-coin cell assembled using these powders for the negative electrode has exhibited a stable capacity higher than 1000 mAh/g with the coulombic efficiency of around 99.3%, both of which are higher values than those of the cell with raw SiO. Electrochemical analysis has revealed that the resistance at the SiOx particle surface decreases potentially with Li2O formation from the beginning of the first lithiation. The decrease in the resistance is further enhanced by the addition of CH4, although more volume change is expected because of the increased crystalline Si phase content. As a result, the core–shell SiO nanocomposite produced by plasma spraying with CH4 becomes advantageous in attaining high capacity and high retention efficiency simultaneously.