Rational design of Fe3O4@C yolk-shell nanorods constituting a stable anode for high-performance Li/Na-ion batteries

Abstract

In the current research project, we have prepared a novel Fe3O4@mesoporous carbon nanorod (denoted as Fe3O4@C) anode with yolk-shell structure for Li/Na-ion batteries via one-pot and surfactant-free synthesis strategy. The yolk-shell structure consists of Fe3O4 nanorod yolk completely protected by a well-conductive mesoporous carbon shell. The substantial void space in the Fe3O4@C yolk-shell nanorod can not only accommodate the full volume expansion of inner Fe3O4 nanorod, but also preserve the structural integrity of the Fe3O4@C anode and develop a stable SEI film on the outside mesoporous carbon shell during the repeated Li+/Na+ insertion/extraction processes. As for lithium storage, the Fe3O4@C electrode exhibits a high specific capacity (1247 mAh g−1), stable cycling performance (a specific capacity of 954 mAh g−1 after 200 cycles at a current density of 0.5 A g−1) and excellent rate capability (specific capabilities of 1122, 958, 783, 577, and 374 mAh g−1 at 0.5, 1, 2, 4, and 8 A g−1, respectively). As for sodium storage, the Fe3O4@C yolk-shell nanorods also maintain a reversible capacity of approximate 424 mAh g−1 at 0.1 A g−1 after 100 cycles.