Interconnected Hollow Si/C Hybrids Engineered by the Carbon Dioxide-Introduced Magnesiothermic Reduction of Biosilica from Reed Plants for Lithium Storage

Silicon, with its natural abundance and high gravimetric capacity, holds tremendous potential for practical Li-ion batteries (LIBs). However, the major issue related to silicon is its huge volume change during the charge/discharge processes, leading to structural degradation and instability. We report herein reed plants-derived interconnected hollow Si/C hybrids fabricated by using CO2 (carbon source) in traditional magnesiothermic reduction. Both the CO2 amount and HCl concentration for the extraction of SiO2 play a significant role on the architecture design and rational composition of the Si/C hybrids during this new synthetic system. Significantly, the Si/C composites with 21 wt % carbon content as anodes for LIBs display a large reversible specific capacity of 1548 mAh g–1 at 100 mA g–1 and a superior specific capacity of 650 mAh g–1 at 500 mA g–1 for 200 cycles and of 1025 mAh g–1 at 2000 mA g–1. The outstanding rate property and good cycling performance are ascribed to cooperativity of morphologies and structures of the Si/C composites, possessing a large pore volume and specific area, unique interconnected hollow structure, and high electrical conductivity. Additionally, such biomass-derived Si/C hybrid synthetic route with low cost and large-scale production merits probably accelerates the commercialized application of Si-based anodes for LIBs.