Nitrogen-doped hierarchical carbon spheres derived from MnO2-templated spherical polypyrrole as excellent high rate anode of Li-ion batteries

Hierarchical nitrogen-doped carbon spheres (NCSs) prepared by annealing the MnO 2 -templated spherical polypyrrole (PPy) at 450 or 600   °C were tested as anode materials of Li-ion batteries. The NCSs annealed at 450   °C exhibited higher nitrogen content, more amorphous carbon structure, and lower surface area as compared to the sample annealed at 600   °C. The specific capacities and rate performances of both NCSs samples were much higher than that of commercial mesocarbon microbeads (MCMBs). The NCSs annealed at 600   °C exhibited higher capacity at low current density (<0.5   A   g −1 ) but more rapid capacity decay at elevated current rates referring to the sample annealed at 450   °C. The NCSs annealed at higher temperature also possessed inferior cycling stability, possibly due to its lower electronic conductivity and higher degree of graphitization. A high specific capacity of 250.8   mAh   g −1 was achieved on the NCSs annealed at 450   °C at 3   A   g −1 , demonstrating their high potentiality as anode of high power Li-ion batteries.