Facile and Scalable Synthesis of Porous Si/SiO_x Nanoplates from Talc for Lithium-Ion Battery Anodes

Silicon-based anode materials have attracted attention as a substitute for graphite in commercial purpose because of various advantages including high capacity and wide operating voltage. However, there are difficulties in commercialization because of dramatic volume change during the cycle and the formation of byproducts because of side reactions with the electrolyte and high production cost. Here, we report a facile, low-cost, and scalable approach to synthesize a nanocrystalline porous silicon-embedded silicon oxide nanoplate (p-Si/SiOx) from talc using the magnesio-thermic reduction process with a thermal scavenger (NaCl). The thermal scavenger accommodates the excess thermal energy generated during the magnesio-thermic reduction process, maintaining the unique and attractive 2D structure of talc and forming a mixed phase of Si and SiOx. p-Si/SiOx has a large surface area and high porosity, leading to a reversible capacity of 675 mA h/g even at high current density (5 C, 7.5 A/g); the porous structure maximizes the accessible surface area of electrolytes and ion transport capability. In addition, the reversible capacity retains 79.3% of its original value after 800 cycles under 1 C rate. The synthesis strategy presented here provides a promising method for producing silicon-based anodes with high power and high capacity for next-generation lithium-ion batteries.