Synthesis of mesoporous manganese dioxide/expanded graphite composite and its lithium-storage performance

Abstract

A mesoporous manganese dioxide ($\hbox {MnO}_{2})$/expanded graphite (EG) composite was successfully fabricated using mesoporous silica decorated EG (KIT-6/EG) as a hard template. Different amounts of EG were introduced to the synthetic system to adjust the $\hbox {MnO}_{2}$:EG mass ratio of the composite. X-ray diffraction, transmission electron microscopy, scanning electron microscopy and nitrogen adsorption–desorption analyses were employed to characterize the structure and morphology of the composite. Results show that the distribution of $\hbox {MnO}_{2}$ nanoparticles grown on the EG layers decreases gradually with increasing EG content. Moreover, in the presence of excess EG, the specific surface area of the samples dramatically decreases. As the anode electrode of a Li-ion battery (LIB), the composite ($\hbox {MnO}_{2}\hbox {:EG }= 34{\%}\hbox { w/w}$) exhibits a specific capacity of $\sim$250 mA h $\mathrm{g}^{-1}$ at a current density of $200\hbox { mA g}^{-1}$ for up to 100 cycles, this capacity is much higher than that of pure $\hbox {MnO}_{2}$ ($\sim$10 mA h $\hbox {g}^{-1})$ due to its improved electrical conductivity. The composite also shows good rating performance when the current density is tuned. These results indicate that the composite has potential application as an anode material for next-generation LIBs.