Preparation of Si/TiO₂ Composite by the Sol-Gel Method Using As the Lithium-Ion Battery Anode

Si was a promising anode material for next-generation LIBs due to its extremely large capacity of 4200mAh/g (Li_4.4Si phase). However, during repeated lithium insertion/extraction processes, the accompanied huge volume change (400%) induced the structural failure of the active material and resulted in rapid capacity fading. To overcome this problem, Si/TiO₂ composite with different mole ratio were prepared by the sol-gel method. The inclusion of TiO₂ not only worked as a stable electric conductive pathway but also buffered the volume expansion of the Si during the process of charging and discharging. The Si/TiO₂ composite with different mole ratio of 1:2, 1:3, 1:4 electrode reaches 480mAh/g, 2590mAh/g and 980mAh/g, and it delivered a charge capacity of 461mAh/g, 2510mAh/g and 891mAh/g at the first cycle, corresponding to an initial coulombic efficiency of 96%, 96% and 91%. In contrast, the cell with the pure Si nanoparticle exhibited an initial discharge/charge capacity of 48 and 33mAh/g, respectively, which was much lower than the Si/TiO₂ composite electrode. (paper)