8. Conclusion

In summary, the electrochemical properties of TiO2-V2O5 and NiMn2O4 composites have been demonstrated. Three dimensional, mesoporous, interlinked tube-like ordered architecture of TiO2-V2O5 nanocomposite offers large surface area which enhances the specific capacitance. The composite offers maximum specific capacitance of 310 F g<sup>1</sup> in 1 M KCl solution at 2 mV s<sup>1</sup> scan rate. It is found out that the maximum capacitance value arises from the contribution of inner active sites of the electrode rather than the outer surface. The NiMn2O4 nanoparticles with 8 nm average diameter show spherical shape with BET surface area of 43.6 m<sup>2</sup> g<sup>1</sup> . The agglomerated spinel nanoparticles generate highly porous structures, which can be utilized to fabricate working electrodes of the electrochemical supercapacitors. The electrodes made of NiMn2O4 nanoparticles possess excellent charge storage characteristics, with specific capacitance of up to 875 F g<sup>1</sup> attainable at a scan rate of 2 mV s<sup>1</sup> in 1.0 M Na2SO4 electrolyte solution. The coexistence of Ni and Mn in the lattice of this binary oxide is seen to have a positive effect on the improvement of electrochemical charge storage capability of the electrodes due to enhanced electronic conductivity. Both these two composites demonstrate excellent device performance. The asymmetric device based on TiO2-V2O5 shows specific capacity of 86 F g<sup>1</sup> at 4.2 A g<sup>1</sup> with the maximum energy density (Ecell) and power density (Pcell) about 20.18 W h kg<sup>1</sup> and 5.94 kW kg<sup>1</sup> , respectively. On the other hand the asymmetric device based on NiMn2O4 demonstrates 166.7 F g<sup>1</sup> at current density 1 A g<sup>1</sup> with specific energy density and power density of 75.01 W h kg<sup>1</sup> and 2.25 kW kg<sup>1</sup> , respectively. These superior performances ensure that these composites can be used as the electrodes for future energy storage devices.

Transition Metal Oxide-Based Nano-materials for Energy Storage Application DOI: http://dx.doi.org/10.5772/intechopen.80298
