Carbon encapsulated Fe ₃ O ₄ nanospheres with high electrochemical performance as anode materials for Li‐ion battery

Abstract Transformation‐type anodes such as Fe ₃ O ₄ and other transition‐metal oxides are gaining popularity in rechargeable Li‐ion batteries, but the poor cycling performance and low poor Coulombic efficiency seriously influence their practical applications. Herein, we design a facile method to prepare well‐defined yolk‐shell Fe ₃ O ₄ @C nanocomposites, and test the nanocomposites as anode material for Li‐ion battery. Due to the protection of carbon shell and the loose interspace structure, the capacity of this yolk‐shell Fe ₃ O ₄ @C nanocomposites electrode is approximately 860 mAh g ⁻¹ after 300 cycles at 200 mA g ⁻¹ charge/discharge current density with 2 mg cm ⁻¹ loading. The first Coulombic efficiency is about 73.2% and the average Coulombic efficiency is 99% in the following cycles. The remarkably high specific capacity and excellent cycle performance endow the yolk‐shell Fe ₃ O ₄ @C nanocomposites as a great potential anode for the Li‐ion batteries application.