▎ 摘　　要

Nitrogen-doped pyrolytic carbon coated Fe3O4 nanocrystals supported by large sheet-size graphene (N-pC/Fe3O4/G) were synthesized by a self-assembly process followed by heating to obtain a high-performance anode material. The 3D porous poly-melamine sponge (PMS) acted as a template for the assembly of graphene to form curved and hollow foam structure, and as a source of N-doped carbon coating of Fe3O4 nanocrystals. The N-pC/Fe3O4/G composite exhibits good reversible capacity of 825 mAh/g after 350 cycles at a high current density of 1 A/g, showing much better performance than either one of its two components. Its performance benefits from the long-range conductivity of the graphene foam and the short-range local conductivity of the N-doped carbon coating. (C) 2019 Elsevier B.V. All rights reserved.