A combination of hierarchical pore and buffering layer construction for ultrastable nanocluster Si/SiO_x anode

Porous Si can be synthesized from diverse silica (SiO₂) via magnesiothermic reduction technology and widely employed as potential anode material in lithium ion batteries. However, concerns regarding the influence of residual silicon oxide (SiO_x) component on resulted Si anode after reduction are still lacked. In this work, we intentionally fabricate a cauliflower-like silicon/silicon oxide (CF-Si/SiO_x) particles from highly porous SiO₂ spheres through insufficient magnesiothermic reduction, where residual SiO_x component and internal space play an important role in preventing the structural deformation of secondary bulk and restraining the expansion of Si phase. Moreover, the hierarchically structured CF-Si/SiO_x exhibits uniformly-dispersed channels, which can improve ion transport and accommodate large volume expansion, simultaneously. As a result, the CF-Si/SiO_x-700 anode shows excellent electrochemical performance with a specific capacity of ~1,400 mA·h·g^-1 and a capacity retention of 98% after 100 cycles at the current of 0.2 A·g^-1.