▎ 摘　　要

NOVELTY - Preparing graphene quantum dots involves disassembling waste lithium-ion battery under charge, taking out negative electrode sheet, and mixing negative electrode sheet with deionized water and performing ultrasonic treatment to remove negative electrode current collector in negative electrode sheet to obtain mixed solution. The mixed solution is heated, filtered with suction, and filter residue is washed with hot deionized water until the pH of water washing solution is less than 8 to obtain first precursor. The heating temperature is 80-90 degrees C. The heating time is 1-3 hours. First precursor is mixed with deionized water, heated, and microwave digestion treatment is performed to obtain second precursor. Centrifugal treatment is performed on second precursor taking supernatant. Dialysis is performed on supernatant to obtain third precursor. Molecular sieve adsorption treatment is performed on third precursor. USE - Method for preparing graphene quantum dots (claimed). ADVANTAGE - Method enables to prepare graphene quantum dots that are eco-friendly. DETAILED DESCRIPTION - Preparing graphene quantum dots involves disassembling waste lithium-ion battery under charge, taking out negative electrode sheet, and mixing negative electrode sheet with deionized water and performing ultrasonic treatment to remove negative electrode current collector in negative electrode sheet to obtain mixed solution. The mixed solution is heated, filtered with suction, and filter residue is washed with hot deionized water until the pH of water washing solution is less than 8 to obtain first precursor. The heating temperature is 80-90 degrees C. The heating time is 1-3 hours. First precursor is mixed with deionized water, heated, and microwave digestion treatment is performed to obtain second precursor. Centrifugal treatment is performed on second precursor taking supernatant. Dialysis is performed on supernatant to obtain third precursor. Molecular sieve adsorption treatment is performed on third precursor, and molecular sieve is eluted after molecular sieve adsorption treatment with eluent, and eluent is rotary evaporated to obtain graphene quantum dot. The mass-volume ratio of molecular sieve to third precursor is greater than 1:30.