▎ 摘　　要

NOVELTY - Preparation of three-dimensional graphene, involves preparing graphene oxide, mixing the graphene oxide with flaky graphite as an absorbing additive, and obtaining black, light and fluffy three-dimensional graphene powder by microwave heating at 400-600 W for 10-30 seconds in air atmosphere. USE - Preparation of three-dimensional graphene for supercapacitor cathode and electromagnetic-wave-absorption materials (all claimed). ADVANTAGE - The method is simple, retains the oxygen-containing functional groups on a portion of the graphene surface, enhances the wettability of the surface of carbon material, reduces the electron transfer resistance, and enables quick and economical preparation of three-dimensional graphene. The obtained three-dimensional graphene exhibits a fluffy powder appearance in a macroscopic state, and has a specific surface area of up to 457 m2/g and a stacked layer structure, and provides cathode having high quality. The supercapacitor using the cathode has a specific capacity of 215 F/g and better cycle capacity retention (52% after 20000 cycles). When the three-dimensional graphene is used in for electromagnetic wave absorption, the reflection loss at 14.5-18 GHz is up to -10 dB. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) supercapacitor cathode using the three-dimensional graphene as an active material, foam nickel as a current collector, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder; and (2) electromagnetic-wave-absorption material obtained by melt-mixing the three-dimensional graphene with paraffin wax.