Hierarchical Fe ₃ O ₄ @C nanofoams derived from metal–organic frameworks for high‐performance lithium storage

Abstract

Abstract A facile method was employed to in situ prepare hierarchical mesoporous Fe 3 O 4 @C nanofoams through pyrolysis of a post‐treated MIL‐53(Fe) precursor. Well‐defined carbon network‐encapsulated ultrasmall and uniform Fe 3 O 4 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 −1 after 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 are 833.6, 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 Fe 3 O 4 @C nanofoams should be attributed to the hierarchical foam‐like structure, which can effectively relieve the volume change during the lithiation/delithiation process and facilitate fast lithium‐ion and electron transport.