High-Performance Si/SiOxNanosphere Anode Material by Multipurpose Interfacial Engineering with Black TiO2–x

Silicon oxides (SiOx) have attracted recent attention for their great potential as promising anode materials for lithium ion batteries as a result of their high energy density and excellent cycle performance. Despite these advantages, the commercial use of these materials is still impeded by low initial Coulombic efficiency and high production cost associated with a complicated synthesis process. Here, we demonstrate that Si/SiOxnanosphere anode materials show much improved performance enabled by electroconductive black TiO2–xcoating in terms of reversible capacity, Coulombic efficiency, and thermal reliability. The resulting anode material exhibits a high reversible capacity of 1200 mAh g–1with an excellent cycle performance of up to 100 cycles. The introduction of a TiO2–xlayer induces further reduction of the Si species in the SiOxmatrix phase, thereby increasing the reversible capacity and initial Coulombic efficiency. Besides the improved electrochemical performance, the TiO2–xcoating layer plays a key role in improving the thermal reliability of the Si/SiOxnanosphere anode material at the same time. We believe that this multipurpose interfacial engineering approach provides another route toward high-performance Si-based anode materials on a commercial scale.