Fe3O4 nanoflakes in an N-doped carbon matrix as high-performance anodes for lithium ion batteries.

Fe3O4 nanoflakes in an N-doped carbon matrix (Fe3O4 NF@NC) were prepared by solvothermal synthesis of Fe3O4 nanoflakes and in situ polymerization of pyrrole on the surface of Fe3O4 followed by heat treatment. The Fe3O4 NF@NC is composed of Fe3O4 nanoflakes with a width of 50-60 nm and a thickness of 10 nm dispersed in the N-doped carbon matrix. The carbon content varies from 18% to 50% on controlling the amount of pyrrole added, therefore the Fe3O4 NF@NC with 44% carbon content performs the best. Due to the cooperation of the two-dimensional (2D) structure of Fe3O4 nanoflakes and the N-doped carbon matrix, the obtained Fe3O4 NF@NC (44% carbon content) exhibits electrochemical performance with a reversible capacity of 1046 mA h g(-1) at 0.2 C (1 C = 924 mA g(-1)) over 200 cycles, 662 mA h g(-1) at 1 C after 500 cycles and 600 mA h g(-1) at 5 C over 200 cycles.