Dual-Size Silicon Nanocrystal-Embedded SiO_x Nanocomposite as a High-Capacity Lithium Storage Material

SiO_x-based materials attracted a great deal of attention as high-capacity Li⁺ storage materials for lithium-ion batteries due to their high reversible capacity and good cycle performance. However, these materials still suffer from low initial Coulombic efficiency as well as high production cost, which are associated with the complicated synthesis process. Here, we propose a dual-size Si nanocrystal-embedded SiO_x nanocomposite as a high-capacity Li⁺ storage material prepared via cost-effective sol-gel reaction of triethoxysilane with commercially available Si nanoparticles. In the proposed nanocomposite, dual-size Si nanocrystals are incorporated into the amorphous SiO_x matrix, providing a high capacity (1914 mAh g^-1) with a notably improved initial efficiency (73.6%) and stable cycle performance over 100 cycles. The highly robust electrochemical and mechanical properties of the dual-size Si nanocrystal-embedded SiO_x nanocomposite presented here are mainly attributed to its peculiar nanoarchitecture. This study represents one of the most promising routes for advancing SiO_x-based Li⁺ storage materials for practical use.