Chemical Routes to Graphene-Based Flexible Electrodes for Electrochemical Energy Storage - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 436

Fig. 15 Digital and SEM images of graphene composite papers containing a MnO 2 nanowires
and b LiFePO 4 particles. c Comparison of galvanostatic charge and discharge curves at different
cycles for the graphene-MnO 2 composite paper and MnO 2 nanowire electrode prepared by
conventional method. d Comparison of galvanostatic charge and discharge curves at different
cycles for the graphene-LiFePO 4 composite paper and LiFePO 4 nanoparticle electrode prepared
by conventional method
Figure 15 c shows the comparison of galvanostatic charge/discharge curves for
the graphene-MnO 2 composite paper and MnO 2 nanowire electrode prepared by
conventional method with CB and PVDF binder. The initial reversible capacities
achieved for the free-standing graphene-MnO 2 composite paper was
531 mAh g -1 as LIB anode, the capacity is much higher than that of graphene-free
MnO 2 nanowire electrode (320 mAh g -1 ), indicating that the interspaced graph-
ene layers can facilitate electron and Li-ion transport in the electrode. After 10
cycles, the capacity of graphene-MnO 2 reached 548 mAh g -1 , but the capacity of
graphene-free MnO 2 nanowire electrode rapidly faded to 174 mAh g -1 . Imply the
effective protection of the MnO 2 nanowires by graphene matrix. Similar to the
results of the graphene-MnO 2 composite paper, graphene-LiFePO 4 composite
paper also shows higher reversible capacity (160 mAh g -1 ) compared with elec-
trode prepared by traditional method (140 mAh g -1 ), when tested as LIB cathode
(Fig. 15 d). The improved performance can also be attributed to the acceleration of
electron transport by graphene matrix. Such method is quite versatile and a wide
range of nanomaterials can be applied to composite with graphene to fabricate
flexible electrode for LIBs. Table 1 compares of the performance of several