The composite sphere of manganese oxide and carbon nanotubes as a prospective anode material for lithium-ion batteries

Transition metal oxides and carbonates are emerging anode materials for lithium-ion batteries based on conversion reactions. In this paper, MnO sphere is simply prepared by decomposition of the spherical MnCO₃ precursor, and multi-walled carbon nanotubes (MWNTs) are employed to modify their lithium storage capabilities. It is found that the MnO system has superior battery performance over MnCO₃ although both of their performances could be significantly improved by carbon nanotube backbones. In particular, the MWNTs/MnO composite sphere shows an outstanding electrochemical performance with a comparatively lower lithium extraction potential. The reversible specific capacity at 35 mA g^-1 is ∼1005 mA h g^-1 with an initial coulombic efficiency of ∼68%. After 200 cycles at 130 mA g ^-1, the capacity is slowly decreased from ∼722 mA h g ^-1 to ∼597 mA h g^-1 indicating a retention of ∼83%. Under a high current rate of 715 mA g^-1 (∼1.6 C), it could still deliver ∼447 mA h g^-1. The high conductivity of MWNTs, unique spherical morphology of the composite, facile electron and Li ⁺ transportations in the electrode/electrolyte interface, self-accommodation of the large volume change during discharge/charge and synergetic lithium storage from each component are ascribed for the advanced performance.