▎ 摘　　要

NOVELTY - Manufacture of a silicon-carbon-graphene composite involves mixing a waste silicon sludge with any one of hydrochloric acid, sulfuric acid, and nitric acid, reacting at 80-120 degrees C for 1-10 hours, washing by adding distilled water to the remaining waste silicon sludge by filtering, drying the washed waste silicon sludge solution, dispersing the dried and purified waste silicon sludge evenly in distilled water, ultrasonically treating the dispersion solution in which the waste silicon sludge is dispersed, recovering silicon particles, pulverizing the recovered particles in a state in which 10-200 wt.% carbon precursor is added, ultrasonically spray-drying the silicon-carbon precursor suspension in which the silicon particle surface is pulverized so that the carbon precursor is coated, nozzle-type spray drying the silicon-carbon composite and graphene oxide solution, and heat-treating the spray-dried silicon-carbon-graphene oxide composite at 600-900 degrees C under inert gas atmosphere. USE - Manufacture of silicon-carbon-graphene composite used as anode material for lithium secondary battery. ADVANTAGE - The method produces silicon-carbon-graphene composite having improved re-aggregation inhibition property and dispersibility of carbon nanotubes, by uniformly dispersing the carbon material in the carbon nanotubes to alleviate the volume change and improving electrical contact, thus improving discharge capacity and output characteristics of the battery. DETAILED DESCRIPTION - Manufacture of a silicon-carbon-graphene composite involves performing mechanochemical bonding by mixing a waste silicon sludge with any one of hydrochloric acid, sulfuric acid, and nitric acid, reacting at 80-120 degrees C for 1-10 hours, washing by adding distilled water to the remaining waste silicon sludge by filtering while lowering the temperature of the mixed solution of waste silicon sludge and hydrochloric acid to room temperature, drying the washed waste silicon sludge solution, dispersing the dried and purified waste silicon sludge evenly in distilled water, ultrasonically treating the dispersion solution in which the waste silicon sludge is dispersed, recovering silicon particles from the waste silicon sludge by centrifugal separation for 1-60 minutes at a rotation speed of 100-1000 rpm, pulverizing the recovered particles in a state in which 10-200 wt.% carbon precursor is added, ultrasonically spray-drying the silicon-carbon precursor suspension in which the silicon particle surface is pulverized by passing an atomized material through a carrier gas which is an inert gas comprising argon, nitrogen and helium at a flow rate of 0.5-5 L/minute at 200-450 degrees C to a tubular heating furnace so that the carbon precursor is coated at an ultrasonic frequency of 1-2.5 MHz, nozzle-type spray drying the silicon-carbon composite and graphene oxide solution by spraying a solution of a silicon-carbon composite and graphene oxide into aerosol droplets through a nozzle, passing the sprayed droplets through a tubular heating furnace through a carrier gas at a flow rate of 5-10 L/minute to dry at 180-220 degrees C and heat-treat, transporting the droplets to the heating furnace by any one or more gases of argon, helium and nitrogen, and heat-treating the spray-dried silicon-carbon-graphene oxide composite at 600-900 degrees C under inert gas atmosphere.