Preparation of Si nano-crystals with controlled oxidation state from SiO disproportionated by ZrO2 ball-milling

Abstract We demonstrate that a SiO disproportionation reaction can be achieved simply by high energy mechanochemical milling. The planetary ball-milling of ZrO 2 for a few minutes generated Si nano-crystals. Milling conditions including rotation speed, ball number, milling time, and type of ball material were able to control the oxidation states of Si. The ball-milled SiO powder was tested as an anode of a lithium battery. ZrO 2 contamination from the vial and balls was eliminated by dipping the ball-milled SiO powder in (NH 4 )HSO 4 molten salt and heating for 5 min. The disproportionated SiO powder showed characteristics comparable to those of a powder prepared by a conventional heating process taking several hours.