Hierarchical Fe3O4@C nanofoams derived from metal-organic frameworks for high-performance lithium storage

摘要

A facile method was employed to in situ prepare hierarchical mesoporous Fe3O4@C nanofoams through pyrolysis of a post-treated MIL-53(Fe)precursor.Welldefined carbon network-encapsulated ultrasmall and uniform Fe3O4 octahedrons can be obtained by controlling the pyrolysis temperature.This unique artificial shows the excellent lithium storage performance.A reversible discharge capacity of 861.9 mAh·g-1 is observed at 0.1 A·g-1after 300 cycles.Even at a high current density of 1 A·g-1,the reversible discharge capacity can still reach 605.2 mAh·g-1 after 500 cycles.Good rate capability is also observed,as the specific discharge capacities are833.6,729.9,666.8,643.6 and 635.6 mAh·g-1 at current density of 0.2,0.5,0.8,1.0 and 1.2 A·g-1,respectively.The attractive electrochemical performance of Fe3 O4@C nanofoams should be attributed to the hierarchical foamlike structure,which can effectively relieve the volume change during the lithiation/delithiation process and facilitate fast lithium-ion and electron transport.