Microwave synthesis of antimony oxide graphene nanoparticles - a new electrode material for supercapacitors

For the first time, antimony oxide nanoparticles were produced using a microwave technique and evaluated as a supercapacitor electrode. The specific capacitance derived from the material's galvanostatic charge-discharge curve was 98 F g-1 in 1 M Li2SO4 electrolyte at 0.1 A g-1 current density. The charge storage mechanism visible in the CV curve is nearly rectangular and identical to the EDLC charge storage mechanism. Additionally, antimony species were chemically attached to graphene oxide using an antimony(iii) chloride precursor and subsequently microwave aided procedures were used to convert the antimony species to SbO-G nanocomposites. The results of energy-dispersive X-ray spectroscopy demonstrated the pure character of the produced material. In a three-electrode cell arrangement, the resulting composite was electrochemically characterized. The cyclic voltammogram results showed that among the pristine SbO, graphene, and SbO-G materials, SbO-G had a higher specific capacitance value of 37.58 F g-1, at a scan rate of 10 mV s-1. The material has also demonstrated good conductivity characteristics based on electrochemical impedance spectroscopy research. After 3500 galvanostatic charge-discharge cycles, the material had excellent cycling stability of ∼100%. All the remarkable capacitive properties demonstrated by this material indicate that it can be a viable choice in the field of energy storage devices.

Pseudocapacitive Effects of Multi-Walled Carbon Nanotubes-Functionalised Spinel Copper Manganese Oxide

Spinel copper manganese oxide nanoparticles combined with acid-treated multi-walled carbon nanotubes (CuMn₂O₄/MWCNTs) were used in the development of electrodes for pseudocapacitor applications. The CuMn₂O₄/MWCNTs preparation involved initial synthesis of Mn₃O₄ and CuMn₂O₄ precursors followed by an energy efficient reflux growth method for the CuMn₂O₄/MWCNTs. The CuMn₂O₄/MWCNTs in a three-electrode cell assembly and in 3 M LiOH aqueous electrolyte exhibited a specific capacitance of 1652.91 F g^-1 at 0.5 A g^-1 current load. Similar investigation in 3 M KOH aqueous electrolyte delivered a specific capacitance of 653.41 F g^-1 at 0.5 A g^-1 current load. Stability studies showed that after 6000 cycles, the CuMn₂O₄/MWCNTs electrode exhibited a higher capacitance retention (88%) in LiOH than in KOH (64%). The higher capacitance retention and cycling stability with a Coulombic efficiency of 99.6% observed in the LiOH is an indication of a better charge storage behaviour in this electrolyte than in the KOH electrolyte with a Coulombic efficiency of 97.3%. This superior performance in the LiOH electrolyte than in the KOH electrolyte is attributed to an intercalation/de-intercalation mechanism which occurs more easily in the LiOH electrolyte than in the KOH electrolyte.