Fe3O4 nanoparticles encapsulated in multi-walled carbon nanotubes possess superior lithium storage capability

In this work, Fe3O4 nanoparticles are successfully introduced inside multi-walled carbon nanotubes (Fe3O4@MWNTs) by an innovative wet chemical injection method. As anode materials for lithium-ion batteries, the Fe3O4@MWNTs deliver a superior long-term specific capacity of 703.7 mA h g(-1) after 350 cycles at a current density of 100 mA g(-1). The high capacity of Fe3O4 and the distinctive conductive network of cross-linked MWNTs are believed to boost the electrochemical capacity and rate capability. More importantly, the unique encapsulated structure is designed to efficiently cushion the strain induced by volume change during lithiation/delithiation processes. At the same time, size of the Fe3O4 nanoparticles was controlled and they were prevented from agglomerating by the restriction effect of the nanoscaled tube. Both features ensure the structural integrity of the electrode and the stable performance in long-term cycling tests.