High Areal Capacitance of V2O3–Carbon Nanotube Electrodes

V2O3-multiwalled carbon nanotube (MWCNT) electrodes with active mass loading of 30 mg cm−2 and ratio of active material mass to current collector mass of 33% have been developed for charge storage in electrochemical supercapacitors. Good electrochemical performance at high active mass loading allowed for an electrode areal capacitance as high as 4.4 F cm−2 and low electrode resistance. This high performance was, in part, achieved using an advanced colloidal processing method, which involved the use of lauryl gallate (LG) as a dispersant. It was demonstrated that LG allowed for good dispersion of both V2O3 and MWCNT and facilitated their mixing. An electrode activation procedure (AP) was also developed, and contributed to the high capacitance and low resistance at high active mass loadings. To further understand the AP, as received and ball milled V2O3 electrodes were investigated using cyclic voltammetry and impedance spectroscopy before and after activation, as well as with cycling stability. This, coupled with XRD, XPS and SEM data provided an insight into the composition and morphology changes of the active material. The influence of particle size on electrode capacitance, cyclic stability and capacitance retention at high charge-discharge rates has been analyzed. The results of this investigation showed that V2O3-MWCNT composites are promising for practical applications in electrochemical supercapacitors.