A New Approach to Synthesis of Porous SiOx Anode for Li-ion Batteries via Chemical Etching of Si Crystallites

Unlike previous HF etching of Si oxides to produce porous Si a new concept for the preparation of porous SiOx was suggested adopting Si as a pore generating agent and Si oxides as template using NaOH solution. The heat treatment of pristine SiO at 900 °C provided nano-crystalline Si within the SiOx matrix. The nano-crystalline Si was dissolved to provide pore size of 200∼500 nm, while most of the SiOx matrix remained as a template during NaOH etching. The surface area of the etched SiO was increased more than 5 times compared with not-etched SiO. The porous SiOx anode exhibited a stable reversible capacity of about 1240 mAh g−1 over 100 cycles at 0.2 C.