Novel N-doped carbon encapsulation of nanoFe3O4 to improve electrochemical properties of lithium ion battery

To solve the volume expansion problem of Fe3O4 nanoparticles (nmFe(3)O(4)), a facile, green, and industrializable preparation of N-doped carbon-encapsulated nmFe(3)O(4) (nmFe(3)O(4)@N-doped C) is designed. This nmFe(3)O(4)@N-doped C is prepared through pyrolysis in nitrogen atmosphere of nmFe(3)O(4) encapsulated by polyaniline (PANI@nmFe(3)O(4)) which is obtained through oxidative polymerization of aniline on the surface of nmFe(3)O(4). In comparison with the capacity (113 mAh g(-1) at 0.1C) of nmFe(3)O(4), the nmFe(3)O(4)@N-doped C electrode exhibits a high reversible capacity of 400 mAh g(-1) after 500 cycles. Even at 4C, the nmFe(3)O(4)@N-doped C electrode presents 160 mAh g(-1) capacity, which is much higher than 30 mAh g(-1) of the nmFe(3)O(4) electrode. The results suggest that the N-doped carbon shell layer obtained from PANI is effective to inhibit volume expansion of nmFe(3)O(4) core and maintain the electron and ion transport channels after long cycles.