Cauliflower-like MnO@C/N composites with multiscale, expanded hierarchical ordered structures as electrode materials for Lithium- and Sodium-ion batteries
MnO@C/N composite with expanded cauliflower-like morphology was prepared via one-pot L-tryptophan assisted hydrothermal method following by annealing in Ar atmosphere. The cauliflower structure was assembled by porous nanowires that composed of MnO nanoparticles wrapped by continuous N-doped amorphous carbon matrix. Superior electrochemical performances were obtained in both lithium/sodium ion batteries. And the reaction kinetics of MnO@C/N in lithium/sodium ion batteries were analyzed and compared. More than 837 mAh g¿1 could be retained after 300 cycles at 500 mA g¿1. And a high reversible capacity of 336 mAh g¿1 at 5000 mA g¿1 also demonstrate the excellent rate performance of MnO@C/N for LIBs. As to SIBs, 123 mAh g¿1 could be maintained after 200 cycles at 100 mA g¿1. The superior performances could be attributed to the peculiar porous micro-nano structure and N-doped amorphous carbon coating. The reaction kinetics results revealed that the capacitive-controlled capacity would dominate of the electrochemical performance in SIBs and the diffusion-controlled capacity could play a more important role in LIBs, due to the atom weight and size of Na+ is larger than Li+.