In this paper, we report an effective, simple, and cost-effective strategy of electrochemical deposition to prepare hausmannite Mn3O4 thin films for the applications of supercapacitors. Various precursor concentrations and deposition durations were manipulated to tailor the surface morphologies of Mn3O4 nanostructures and to optimize their electrochemical performances. The Mn3O4 samples prepared at 0.05 M Mn(NO3)2 solution for 30 min delivered a large gravimetric specific capacitance of 210 F g−1 at a current density of 0.5 A g−1, and a good rate capability over other samples. This superior electrochemical performance may be attributed to the improved electrode conductivity with increased accessible area for electrolytes ions. Furthermore, a nanocomposite film based on Mn3O4/carbon foam was fabricated by utilizing the developed optimized conditions. The Mn3O4/carbon foam films exhibit an excellent specific capacitance with negligible degradation in retaining specific capacitance values up to 4000 cycles. These findings could further broaden the applications of hausmannite Mn3O4 in electrochemical energy storage electrodes.Electronic supplementary materialThe online version of this article (doi:10.1007/s40820-015-0074-0) contains supplementary material, which is available to authorized users.

To overcome the obstacle of low energy density, one of the most intensive approaches is the development of new materials for supercapacitor electrodes. Most explored materials today are carbon particle materials, which have high surface areas for charge storage. But in spite of these large specific surface areas, the charges physically stored on the carbon particles in porous electrode layers are unfortunately limited. Regarding advanced supercapacitor electrodes, metal oxides are considered the most promising material for the next generation of supercapacitors owing to their unique physical and chemical properties. In this chapter, the rational design and fabrication of metal oxide nanostructures for supercapacitor applications are addressed.

Cobalt sulfide (CoS) has been widely applied in the development of high-performance supercapacitors. However, the morphological stability of CoS remains an issue during the charging-discharging procssses. Herein, vertical graphene is...