The Fe 3 N modified Fe 3 O 4 nanoparticles with an excellent performance in lithium-ion batteries were prepared via a one-step and an efficient method. The layer of Fe 3 N could significantly decrease the variation of volume and enhance the conductivity of Fe 3 O 4 simultaneously during the reaction of lithium ions in the charge-discharge process. There are two main advantages of this material: (1) their size distribution, ranging from 100 to 500nm and (2) the fact that these particles are connected with each other by the Fe 3 N layer. These two features allow such material to exhibit a high reversible capacity of 739 and 620mAhg −1 after each 60 cycles at the current density of 50 and 200mAg −1 , respectively. More importantly, since its introduction, this new concept of coating metal oxides with a layer of metal nitride to form core-shell structured metal oxide@metal nitride can be widely applied in the fields of catalysis, electrochemistry, energy, environmental and materials science with improved performance.