Constructing Fe3O4@N-rich Carbon Core-Shell Microspheres as Anode for Lithium Ion Batteries with Enhanced Electrochemical Performance

Graphical abstract: The peanut-like N-rich carbon coated Fe3O4 core-shell composites exhibited excellent electrochemical performance. - Abstract: Highly regulated peanut-like Fe3O4@N-rich carbon (Fe3O4@CN) core-shell microspheres were prepared using a solvothermal method, combined with a facile surfactant (sodium dodecyl sulfate) directed chemical polymerization and subsequent thermal treatment process. As anode electrode materials for Li-ion batteries, the as-prepared Fe3O4@CN composites exhibit higher specific capacity and better cyclic stability than bare Fe3O4. The reversible specific capacity of Fe3O4@CN composite is 670 mAh g−1 in the voltage range of 0.01-3.0 V after 30 cycles with no noticeable fading compared with bare Fe3O4(100 mAh g−1). The enhanced electrochemical performance of the composites can be attributed to peanut-like Fe3O4@CN core-shell structure in which monodisperse Fe3O4 particles are entirely coated in the controllable and uniform carbon shell, and the surface contact among carbon shells further improves electronic conductivity due to slight agglomeration of composites after thermal treatment. Moreover, the residual nitrogen in the carbon crystal lattice resulted from the carbonization of polypyrrole enhances the electronic conductivity and brings active defects for the diffusion of lithium ion