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Pulverization Control by Confining Fe3O4 Nanoparticles Individually into Macropores of Hollow Carbon Spheres for High-Performance Li-Ion Batteries

Yan, Zhijun, Jiang, Xiaobin, Dai, Yan, Xiao, Wu, Li, Xiangcun, Du, Naixu, He, Gaohong
ACS applied materials & interfaces 2018 v.10 no.3 pp. 2581-2590
anodes, carbon, electrochemistry, encapsulation, iron oxides, lithium batteries, macropores, nanoparticles
In this article, double carbon shell hollow spheres which provide macropores (mC) for ultrasmall Fe₃O₄ nanoparticle (10–20 nm) encapsulation individually were first prepared (Fe₃O₄@mC). The well-constructed Fe₃O₄@mC electrode materials offer the feasibility to study the volume change, aggregation, and pulverization process of the active Fe₃O₄ nanoparticles for Li-ion storage in a confined space. Fe₃O₄@mC exhibits excellent electrochemical performances and delivers a high capacity of 645 mA h g–¹ at 2 A g–¹ after 1000 cycles. Even at 10 A g–¹ or after 1000 cycles at 2 A g–¹, the porous carbon structure was well maintained and no obvious aggregation and pulverization of the Fe₃O₄ nanoparticles was observed, although the volume of the active Fe₃O₄ particles was expanded to 40–60 nm compared to that of the original particles (10–20 nm). This can be due to the in situ embedment of one Fe₃O₄ nanoparticle into one macropore individually. The uniform dispersion and confinement of the Fe₃O₄ nanoparticles in the macropores of the carbon shell could effectively accommodate severe volume variations upon cycling and prevent self-aggregation and spreading out from the carbon shell during the expansion process of the nanoscale Fe₃O₄ particles, leading to improved capacity retention. Our work confirms the effectiveness for pulverization control by confining Fe₃O₄ nanoparticles individually into macropores to improve its Li-ion storage properties, providing a novel strategy for the design of new-structured anode materials for Li-ion batteries.