Patent ID: 10069142

Abstract:
The invention provides a rotary tubular furnace including a rotatable furnace tube having an inlet end through which silicon compound particles (SiOx where 0.5≤x<1.6) are put therein and an outlet end through which the particles coated with carbon are taken out therefrom; and a heating chamber having a heater to heat the furnace tube, wherein the furnace tube is composed of a heat portion inside the heating chamber and a non-heat portion outside the heating chamber, a length B of the heat portion and an overall length A of the furnace tube satisfy 0.4≤B/A<1, and a distance C between the heat portion and the outlet end and the overall length A satisfy 0.04≤C/A≤0.35. This furnace can inhibit clogging of the furnace tube and mass-produce a negative electrode active material for a non-aqueous electrolyte secondary battery having a high capacity with inhibited variations in the amount of carbon coating and crystallinity.