Porous Fe3O4–NCs-in-Carbon Nanofoils as High-Rate and High-Capacity Anode Materials for Lithium-Ion Batteries from Na–Citrate-Mediated Growth of Super-Thin Fe–Ethylene Glycolate Nanosheets

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• 作者：Chuan Ding ; Yanwei Zeng ; Liangliang Cao ; Longfei Zhao ; Qiuyu Meng
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：March 30, 2016
• 年：2016
• 卷：8
• 期：12
• 页码：7977-7990
• 全文大小：863K
• ISSN：1944-8252

文摘

Porous Fe₃O₄/C composite nanofoils, characterized by a thickness of ∼20 nm and with ∼8 nm open pores and ∼5 nm Fe₃O₄ nanoparticles embedded in the carbon matrix, were prepared for the first time using Na–citrate to mediate the growth of hexagonal Fe–ethylene glycolate nanosheets and subsequently annealing them at 350 °C in N₂. It has been found that the Fe–ethylene glycolate nanosheets can be effectively slimmed by increasing the concentration of Na–citrate, and the microstructures of Fe₃O₄/C nanocomposites may be tailored by the annealing temperature. When tested as the anode materials in LIBs, the Fe₃O₄/C nanofoils obtained after annealing at 350 °C were found to exhibit superior electrochemical performance due to its optimal microstructure, featured by a reversible capacity of 1314.4 mAh g^–1 at 0.4 A g^–1 over 100 cycles, 1034.2 mAh g^–1 at 1 A g^–1, and 686.4 mAh g^–1 at 5 A g^–1 after 500 cycles, whereas the annealing treatments at 450 and 550 °C render the Fe₃O₄/C nanocomposites with the inferior electrochemical performances as a result of shrinking porous microstructures and coarsening of Fe₃O₄ nanoparticles in the carbon matrix. With a particle-size control model proposed herein, the cycle discharging behaviors of the Fe₃O₄/C nanocomposites with different microstructures are well explained from the perspective of the local confinement of Fe₃O₄ nanoparticles inside the carbon matrix and their evolution in size and composite microstructure during the charge/discharge cycling.