Investigations of SWCNT/Polyoxometalates hybrid materials as electrode for supercapacitors

Abstract

Future societal and environmental needs have called in for a need to develop more efficient and sustainable energy storage systems of high specific power and long durability. Presently, the use of supercapacitor as an energy storage device is often limited by the charge storage capability. This major hindrance becomes the main cause of current supercapacitors having low energy density. This provoked a greater scientific interest in the exploration of new electrode materials.

Presently, there are little studies of hybridizing polyoxometalates with carbon nanotubes as electrode materials for supercapacitors. In this study, we identify polyoxometalate TBA-PV2Mo10O40 (TBAPV2Mo10, TBA= Tetrabutylammonium) together with single-walled carbon nanotubes (SWCNTs) as electrode materials for supercapacitors. Investigations of electrochemical properties of SWCNTs/ TBA-PV2Mo10 are carried out by employing electrochemical techniques such as galvanostatic charge-discharge and cyclic voltammetry in acidic aqueous electrolyte. The best ratio for SWCNT: TBA-PV2Mo10, with the overall best electrochemical properties is determined.

To explore the potential of this new hybrid material, SWCNTs/H5PV2Mo10O40 hybrid material is also used for comparison in terms of their specific capacitance, energy and power densities as well as their cycling stability for reliability of the devices.

SWCNTs/ TBA-PV2Mo10 hybrid device demonstrates great potential for use as electrode materials. The hybridization produces a synergizing effect whereby the polyoxometalate contribute to the pseudocapacitance while the SWCNTs contribute to the double-layer capacitance. As a result, the hybrid material is able to achieve a significantly high specific capacitance value of 294 F/g, together with a high energy and power densities of 10 W.h/ kg and 17700 W/kg respectively. The device also shows great cycling stability, which highlight the potential of the hybrid material as a supercapacitor.