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

摘要

A mesoporous manganese dioxide (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 thesynthetic system to adjust the MnO$_2$:EG mass ratio of the composite. X-ray diffraction, transmission electron microscopy, scanning electron microscopy and nitrogen adsorptiona??desorption analyses were employed to characterize the structure and morphology of the composite. Results show that the distribution of 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 (MnO$_2$:EG $=$ 34% w/w) exhibitsa specific capacity of $sim$250 mAh g$^{a??1}$ at a current density of 200 mA g$^{a??1}$ for up to 100 cycles, this capacity is much higher than that of pure MnO$_2$ ($sim$10 mAh g$^{a??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 ananode material for next-generation LIBs.