▎ 摘　　要

NOVELTY - Preparation of few-layer graphene involves adding biomass waste to hydrothermal reactor filled with alkali solution, reacting at 120 degrees C, cooling reaction product to room temperature, filtering, diluting filter residue with water, ultrasonically cleaning, filtering, drying filter residue, calcining obtained pretreated biomass waste under protective atmosphere, soaking obtained carbonized material in acid solution, filtering, cleaning filter residue with water, and graphitizing obtained biomass carbon by heating at rate of 20 degrees C/minute or more to 2400 degrees C or more under argon atmosphere. USE - Preparation of few-layer graphene used in lithium ion battery and supercapacitor. ADVANTAGE - The method enables economical preparation of graphene with 2-10 layers, high yield and electroconductivity, reduced defects and oxy groups, and small carbon layer interval, by simple process. The battery is manufactured using the few-layer graphene, by environmentally-friendly process.