▎ 摘　　要

NOVELTY - The method involves (a) subjecting cellulose to heat treatment under an inert atmosphere and a sealed condition, and (b) applying pressure to the cellulose at a pressure of 100-500 Pa, where the heat treatment is carried out under the condition of heat treatment. USE - Method for preparing graphene quantum dot/hard carbon heterojunction material of a material cathode in a potassium ion button cell (all claimed). Uses include but are not limited to electronic device, sensor, secondary battery, catalytic and photoelectric detector. ADVANTAGE - The method has simple technique, flexible and controllable, high performance and high efficiency. The prepared graphene quantum dot/hard carbon heterojunction applied to the cathode ion buckle type battery of the material, the product performance is excellent. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a graphene quantum dot/hard carbon heterojunction material of a material cathode in a potassium ion button cel.