Macroporous Fe3O4/Carbon Composite Microspheres with a Short Li+ Diffusion Pathway for the Fast Charge/Discharge of Lithium Ion Batteries

Macroporous Fe3O4/carbon composite and core-shell Fe3O4@carbon composite microspheres have been prepared by means of one-pot spray pyrolysis. The addition of polystyrene (PS) nanobeads to a spray solution containing an iron salt and poly(vinylpyrrolidone) (PVP) led to macroporous Fe3O4/carbon composite microspheres, the carbon and iron components of which are uniformly distributed over the entire composite microsphere. The pore-size distribution curve for the macroporous Fe3O4/carbon composite shows distinct peaks at around 10 and 80 nm. An electrode prepared from the macroporous Fe3O4/carbon composite microspheres showed better cycling and rate performances than an electrode formed from core-shell Fe3O4@carbon composite microspheres. The initial discharge and charge capacities of the macroporous Fe3O4/carbon composite microsphere electrode were determined to be 1258 and 908 mA h g(-1) at 2 Ag-1, respectively, and the corresponding initial coulombic efficiency was 72%. The composite microsphere electrode cycled 500 times at 5 Ag-1 showed a high discharge capacity of 733 mA h g(-1).